Alpha-7A
Alpha-7L
Alpha Continuous Air Monitor
Technical Manual
Thermo Eberline
A Division of ThermoElectron
Alpha-7 Alpha Continuous Air Monitor
Copyright 2002, Thermo Eberline. All rights reserved.
Revision History:
Original Issue
April 2002
Alpha-7L and Radial-Entry Sampling Head
Table of Contents
Overview
1
Introduction ............................................................................1
Physical Specifications..........................................................2
Communications....................................................................3
Stand-Alone Configuration ..............................................3
Operator Interface .................................................................4
Alpha-7L Differences .......................................................5
Instrument Software...............................................................5
Client Software ......................................................................7
Software Updates ..................................................................8
Alpha-7 Hardware..................................................................9
Single Board Computer (SBC) ........................................9
Display Board...................................................................9
Multi-Channel Analyzer (MCA) Board.............................9
Theory of Operation
11
Technological Advancements.............................................11
Spectrum Measurement ......................................................12
Spectrum Acquisition .....................................................12
Peak Shape Factors ......................................................12
Curve Fitting ........................................................................13
General Algorithm..........................................................13
Peak Shape Training .....................................................14
Curve Fit Statistics .........................................................14
Curve Fitting Difficulties..................................................14
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Concentration Calculation...................................................15
Fast and Slow Integration Windows..............................15
History Arrays.................................................................15
Concentration Calculation Method ................................15
Concentration Equation .................................................16
Dose Calculation............................................................17
Region of Interest Calculation .......................................17
Error Handling and Exceptions......................................17
Minimum Detectable Concentration Calculation ................18
Uncertainties in Peak Counts ........................................18
Calculation of the Variance of Net Count Rate .............18
Region of Interest MDC .................................................19
Alarms..................................................................................20
Configuring Your Alpha CAM
21
Network Setup .....................................................................21
Local Setup Using A Monitor And Keyboard......................22
Network Setup Using The Alpha-7 Calibration Wizard......23
Setup Using The Alpha-7 Client .........................................24
Password Access ..........................................................24
Alpha-7 Client Overview ................................................25
Isotope Database ................................................................27
Using The Tree Control To Set Up A CAM ........................28
Elements Of The Tree Control ......................................28
Tree Control Popup Menus ...........................................29
System Menu.................................................................29
Instrument Menu............................................................31
Tool Tips.........................................................................31
Alpha-7 Instrument Parameters ..........................................32
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General Instrument Properties ......................................34
Sample Flow Properties ................................................34
Release Flow Properties ...............................................36
Analog Output Properties ..............................................38
MCA Properties..............................................................39
Versions Properties........................................................40
Alpha-7 Isotope Parameters ...............................................41
General Isotope Properties............................................42
Fast and Slow Alarms Properties..................................44
Simulation Properties.....................................................46
Adding Isotopes...................................................................48
Adding a Region of Interest.................................................49
Removing Isotopes or Regions...........................................50
Using Profiles To Create Standardized Configurations .....51
Profile Overview.............................................................51
Creating A Profile...........................................................51
Loading A Profile............................................................52
Setting Up the Alpha-7 Client Display ................................53
Spectrum Control...........................................................53
Spectrum Control Properties .........................................54
Dose Control ..................................................................55
Dose Control Properties ................................................56
Chart Control..................................................................56
Chart Control Properties................................................57
RadNet Configuration..........................................................58
The RadNetSvr.exe Utility .............................................58
Using the RadNet Server Properties Dialog .................58
Server Properties...........................................................58
Alpha CAM Properties ...................................................59
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IP Addresses Properties................................................60
RadNet Files........................................................................61
Database Data Source Configuration.................................62
Setting Up The File Server ............................................62
Running the ODBC Data Source Administrator............62
Changing The Data Source...........................................62
Filter Paper Considerations ................................................63
Attaching A Vacuum Source ...............................................63
Radial Entry Sampling Head Connection......................63
In-Line Sampling Head Connections.............................63
Routine Operation and Maintenance
65
Status Conditions ................................................................65
Status Descriptions ........................................................65
Alpha-7A Status Annunciations.....................................66
Alpha-7A Status Conditions...........................................67
Alpha-7L Status Annunciations .....................................67
Alpha-7L Status Conditions ...........................................68
Alarms..................................................................................68
Alarm Logging................................................................69
Filter Changes .....................................................................69
Radial Entry Sampling Head .........................................70
In-Line Sampling Head ..................................................70
Alpha-7 Local Display .........................................................71
Display Pages ................................................................71
Scrolling..........................................................................72
Display Timeout Feature ...............................................72
Response Check And Challenge Test ...............................72
Check Source Mode (Alpha-7A Only)...........................72
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Response Check and Challenge Test Mode (Alpha-7L Only)
Power Down (Turning the Alpha-7 Off) ..............................74
Remote Power Down.....................................................74
Local Power Down.........................................................74
Alpha-7 Calibration
75
Smart Head Technology .....................................................76
Smart Head Parameters................................................76
Hot-Swap Capability ......................................................77
Parameter Error Checking.............................................77
Running the Alpha-7 Calibration Wizard............................77
General Information Page...................................................78
Instrument Information and Isotope Configuration Page ...80
Modifications using the Tree Control.............................82
Source Information Page.....................................................82
Source Considerations ..................................................83
Entering New Source Information .................................84
Editing Existing Source Information...............................85
Gain Calibration Phase Page .............................................86
Efficiency Calibration Phase Page......................................87
Flow Calibration Page— Low Flow Measurement ..............88
Flow Calibration Page— High Flow Measurement .............90
Results Page .......................................................................91
Completion Page.................................................................92
Data Logging
93
History Database— A7Log.mdb ..........................................93
Creating A Link To The A7Log Database...........................93
Instrument Information Table ..............................................95
Status Table.........................................................................95
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Isotope Tables ...............................................................95
Spectrum Table ...................................................................97
Spectrum Backup Tables ....................................................97
Starting A New History Database .......................................98
Disabling Data Logging.......................................................98
Troubleshooting
99
Curve Fit Problems..............................................................99
Alarm Problems ................................................................ 101
Status Conditions ............................................................. 101
D/A Output Problems........................................................ 102
Logging Problems............................................................. 103
RadNet Problems ............................................................. 103
Hardware Description
105
Remote Sampling Head Hardware .................................. 105
Detector and Preamp Board ...................................... 105
MCA Board ................................................................. 106
Mass Flow Sensor ...................................................... 107
Display Board ................................................................... 107
Alpha-7A Details ......................................................... 107
Alpha-7L Details.......................................................... 108
Internal Single Board Computer (SBC) ........................... 108
Stack Inlet and Sampling Collection Efficiencies ............ 109
Self-Diagnostics................................................................ 110
Hardware Self-Diagnostics ......................................... 110
Software Self-Diagnostics........................................... 110
Options
111
External Horn.................................................................... 111
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Alpha-7 Wall Mount Bracket ............................................ 111
Radial Head Sampling Head............................................ 111
In-Line Head Sampling Head........................................... 111
In-Line Head Filter Tray Assembly .................................. 112
In-Line Head Source Holder ............................................ 112
In-Line Head Sample Line Adapter.................................. 112
Remote Head Communications Cable ............................ 112
Fluoropore Filters ............................................................. 113
Plutonium Calibration Source .......................................... 113
Thorium Calibration Source ............................................. 113
PCMCIA Adapter .............................................................. 114
Spare Parts
115
Alpha-7 Spare Parts Listing May 2001 ......................... 115
Drawings
117
Alpha-7 Outline Drawing .................................................. 117
Preamplifier....................................................................... 118
Preamplifier Assembly...................................................... 119
MCA Board Schematic ..................................................... 120
MCA Board Component Layout....................................... 123
Display Board Schematic ................................................. 124
Display Board Component Layout................................... 126
Alpha-7L Interface Connector Wiring .............................. 127
Alpha-7A Interface ConnectionsError! Bookmark not defined.
RAP-1 Vacuum Pump
129
RAP-1 Specifications........................................................ 129
Physical Specifications................................................ 129
Available Accessories................................................. 130
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Operating Instructions For RAP-1/RAS-1........................ 131
Theory of Operation For RAP-1 Regulated Air Pump..... 131
Maintenance ..................................................................... 132
Model RAP-1 Parts List.................................................... 134
Model RAP-1/RAP-1R Repair Kits................................... 134
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Overview
Introduction
The Thermo Eberline Alpha-7 collects airborne particulates and measures the concentrations
of alpha-emitting isotopes by continuously passing air though a filter paper using an external
vacuum source that may be a regulated air pump or a house vacuum system. The active
surface of the filter paper is mounted close to a double-diffused junction detector that
measures the alpha emissions. The Alpha-7 determines the energy of the particles using a
multi-channel analyzer and a unique library-directed peak-fitting algorithm to accurately
separate and quantify concentrations of specific isotopes of interest. Once the isotopes and
their activity on the filter paper is known, the Alpha-7 uses the measured volume of air that
has passed through the filter paper to calculate the concentration of the isotope in the
sampled air and the accumulated dose. The monitor displays the concentration or dose on a
high-visibility vacuum fluorescent display. This information is also available using the Alpha-7
Client software or RadNet software over a standard Ethernet or wireless network. The data
can be logged in an ODBC compliant format and can be easily viewed and analyzed using
Microsoft Access. The Alpha-7 is a PC-based instrument with a Pentium class
microprocessor running the Windows NT 4.0 operating system.
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Physical Specifications
Detector:
Efficiency:
Sensitivity:
Sample Rate:
Dimensions:
Weight:
Connections:
Power:
Air inlet:
Analog Inputs:
Analog Outputs:
Relay contacts:
Pump:
Recommended
Filter Paper:
Vacuum Drop:
Solid state, 490 mm² active area, negative bias
Pu-239 20% (4 pi)
<2 DAC-hours for Pu-239
0.5 to 2 CFM (14 to 60 lpm)
Display Unit: 12.25 ? 11 ? 6.5 inches (H W D) (31.1 ? 27.9 ? 16.5 cm)
In-Line Sampling Head: 14.5 x 7.5 x 7.5 inches (H W D) (36.8 x 19.0 x 19.0 cm)
Radial-Entry Sampling Head: 9.5 x 8.5 x 9 inches (H W D) (24.1 x 21.6 x 22.9
cm)
Display Unit: 10 pounds (4.5 kg)
In-Line Sampling Head: 9 pounds ( 4.1 kg)
Radial Sampling Head: 6.5 pounds ( 2.9 kg)
RJ-45 for 10/100-Base-T Ethernet (calibration and/or networking)
PS2 Keyboard/Mouse Connector (local control of the Alpha-7)
External Video DB15 (local view of the spectrum and for calibration)
Screw connections: terminal blocks for analog input, analog output, and double
pole, double throw alarm relays. Alpha-7L only, an 11 pin military connector is
prewired for a 4-20 mA loop-powered current loop, a 12 volt nominal output
indicating Normal operation, and the alarm relay contact outputs.
90 to 264 VAC, 50/60 Hz, less than 100 Watts
The Alpha-7 standard configuration utilizes a radial inlet sampling head, which is
primarily intended to sample ambient room air. An optional in-line sampling head
is available with a 1 inch I. D. pipe inlet with light baffle cap. An optional 1-inch
I.D., 1 ¼ inch O. D. adapter is available for compression fitting connection to
standard 1 ¼ inch O. D. stainless steel tubing
0 or 4 to 20 mA for a signal proportional to stack flow
A 4 to 20 mA loop powered analog current signal that can be assigned to any one
desired measured item. For example, Slow Dose, Slow Concentration, Fast
Concentration, Sample Flow Rate, and Stack Flow Rate. The analog output
always displays the measurement selected for page 1 of the display.
Screw connections for Alarm, Fail and High Activity Alarms. The alarm relay is
pre-wired to the military connector.
3/8 inch NPT male pipe connection for vacuum supply. Recommended flow rate
is1.5 cubic feet per minute (or 42 lpm)
Millipore 5 micron 47mm Black Fluoropore, Catalog number SA1J408V2
4 inches of Hg at 1.5 cubic feet per minute
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Communications
The Alpha-7 uses Ethernet (IEEE 802.3), or optionally WiFi wireless (IEEE 802.11b),
communications. The standard Alpha-7 is delivered with an RJ-45 connector and uses
10/100-Base-T Ethernet. The simplest method of communicating with an Alpha-7 is to use a
single computer with the TCP/IP protocol drivers, a network card and a standard crossover
cable to connect the two. For communications to be established, the Alpha-7, and the
computer connected to it, must have compatible IP addresses and subnet masks.
Data transmitted over the Ethernet network to and from the Alpha-7 Client and Alpha-7
Calibration Wizard programs is transmitted using Transmission Control Protocol / Internet
Protocol, or TCP/IP. This method of data transmission insures data integrity and receipt.
When data is transmitted from the Alpha-7 for RadNet use, it is transmitted as Universal
Datagram Packets (UDP), which is “connectionless”and does not insure data receipt, but
requires less overhead and minimizes network traffic.
Data is communicated to the Alpha-7 Client program via both polls and broadcasts. Polled
data is data requested by the Alpha-7 Client and is typically used for parameter, spectrum and
history. Dose and concentration data, which is updated regularly such as isotope readings
and status messages, are broadcast from the Alpha-7 to each Alpha-7 Client that is
recognized as having established a connection to that particular Alpha-7. Broadcast data is
transmitted every fifteen second or every minute and will not always match the actual display
at the Alpha-7, which is updated every second.
Software updates are handled through the network connection. The Alpha-7 SBC (Single
Board Computer) does not have a floppy disk, removable hard disk, or CD drive. This means
that all software maintenance is done through the network connection. While additional
hardware (in the form of disk drives, CDs, etc.) can be added, it is not needed for normal
operation. If additional hardware becomes necessary, it must be added locally by connecting
a keyboard, mouse and monitor to the Alpha-7 itself.
Stand-Alone Configuration
If no Ethernet network connection is available or desired, changing parameters can be
accomplished by connecting a SVGA monitor, keyboard and mouse directly to the Alpha-7.
These connections are available on the right side of the unit as the user is facing the display.
This allows the operator to work using the SBC built into the Alpha-7.
Running the Alpha-7 Client software locally at the Alpha-7 allows the modification of all
operating parameters in exactly the same environment that the remote client provides. The
Alpha-7 Calibration Wizard can also be run locally in this manner, again providing all the
functionality that is available when running remotely. The Alpha-7 Client software comes preinstalled on the Alpha-7. This provides the user with the ability to immediately connect a
monitor and keyboard and monitor the status of the instrument. The Alpha-7 Calibration
Wizard is installed on Alpha-7A models, but not on Alpha-7L models. Since the Calibration
Wizard provides the user with the ability to change critical parameters, its use should be
controlled administratively.
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CAUTION: Putting the Alpha-7 Calibration Wizard software on the Alpha-7 will give any
user with network access the ability to change critical calibration parameters.
Operator Interface
The local operator interface is very simple. A highly visible alphanumeric vacuum fluorescent
display is used to display up to 10 pages of information. These pages can be configured to
display as much or as little information as desired, including concentrations, dose, flow data,
etc. The instrument status is always displayed on Page 0.
To keep the system simple to use, the Alpha-7 does not have the option of displaying a
spectrum in the instrument display. Please keep in mind that, if desired, the Alpha-7 can be
used with an external SVGA monitor or flat panel display to show the spectrum with the
Alpha-7 Client program running in the monitor, or with the Alpha-7 Client running on a
network PC connected to the Alpha-7.
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A red flashing beacon and a Sonalert audible annunciator are used to annunciate alarms. The
Alpha-7 can support both concentration and dose alarms simultaneously. There are three
lights - green for Normal condition, yellow for an Alert condition and red for High Alarm .
The High Alarms can be actuated by either a concentration alarm or dose alarm. The Alert
Alarm can be actuated only by a concentration alert. The Normal light will be lit if there are no
abnormal conditions, including failures. A flashing Normal light indicates that at least one of
the alarms set in the instrument is below the Minimum Detectable Concentration (MDC) or
Minimum Detectible Activity (MDA) for that isotope. The default display units for isotope data
are concentration units (e.g. pCi/liter or DAC) but can be factory-configured for dose (e.g. pCi
or DAC-h).
Alpha-7L Differences
The Alpha-7L front panel has different lights and labeling than the Alpha-7A. Instead of the
High Alarm and Alert Alarm lights, it has Hot Job and Trouble lights. The Hot Job light is
bright blue in color and indicates that the instrument is configured to alarm on concentration,
instead of Dose, for rapid annunciation of large releases. Dose alarming is the default for
non-Hot Job CAMs. The Trouble light is yellow and indicates a problem with the instrument
requiring operator attention. The default display units for Alpha-7L isotope data are dose units
(e.g. pCi or DAC-h).
Instrument Software
The Alpha-7 is a PC-based instrument running the Windows NT 4.0 operating system. To
provide full functionality, Thermo Eberline uses three separate software packages. These
are:
A7SERVER.EXE
RADNETSVR.EXE
EBERLOGGER.EXE
The primary instrument control software that acquires spectrum data,
identifies isotope peaks, calculates activity, concentration and dose,
measures the flow and drives the display and alarm annunciators. This
program runs automatically whenever the Alpha7 is started. In addition to
the measurement and annunciation functions, it communicates with the
Alpha-7 Client software by sending the necessary information.
This software queries the A7SERVER software and provides RadNetcompliant information over an Ethernet network. The RadNet client software,
which collects and displays the data, is not automatically provided with the
Alpha-7. It is available as a separate product from Thermo Eberline.
The EBERLOGGER.EXE program is the data-logging client that runs locally
on the Alpha-7. Alpha-7 Client requests for historical chart data are made
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directly to EBERLOGGER, which gathers the required data from the
database, and then returns the data to the requesting program.
In addition, seven other files are required for the Alpha-7 to function. These include six
Dynamic Linked Libraries (DLL) files which contain many of the Alpha-7 Client graphic and
display functions. The Alpha-7 also requires several database files and templates, including
Isotopes.mdb, which is the isotope library for the Alpha-7. In addition, there are two text files
used to define the RadNet configuration setup parameters for the Alpha-7. These text files
will be described in the RadNet Configuration section.
A shortcut to the startup.bat file is put in the Microsoft Windows NT “Startup”group. The batch
file starts automatically when the instrument is powered up starting EBERLOGGER.EXE,
A7SERVER.EXE, and if RadNet support is required, RADNETSVR.EXE.
A typical Alpha-7 directory structure follows:
Eberline\
Alpha-7\
A7CALIB.EXE
A7CLIENT.EXE
A7CLIENT.A7C
A7SERVER.EXE
RADNETSVR.EXE
EBERLOGGER.EXE
CHART.DLL
DOSE.DLL
RADNETUI.DLL
SPECTRUM.DLL
TREE.DLL
UDPDLL.DLL
REGA7.BAT
STARTUP.BAT
RNISOTOPES.TXT
RNLIST.TXT
ATL.DLL
DATA\
ISOTOPES.MDB
HISTORY\
A7LOG.MDB
EMPTY DATABASE\
A7LOG.MDB
UPDATES\
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Client Software
A7CLIENT.EXE
A7CALIB.EXE
TREE.DLL
SPECTRUM.DLL
DOSE.DLL
CHART.DLL
RADNETUI.DLL
A7CLIENT.A7C
This is the Alpha-7 Client software that runs on the remote PC (which can also
be used on the Alpha-7 itself with a keyboard and mouse attached) to view the
information from the Alpha-7 and to configure the measurement parameters on
the Alpha-7.
This is the Alpha-7 Calibration Wizard software that can be run locally (if it is
installed on the Alpha-7) or on a remote PC and is used for the calibration of the
Alpha-7. A7CALIB.EXE automates the calibration process by performing a low
and high gain test to determine the optimum gain for the instrument to align the
energy scale, and then performs an efficiency test to determine the intrinsic
detector efficiency. Next, a flow meter calibration is performed by measuring
known input flows and automatically adjusting the flow calibration values to
match. It then automatically stores these parameters back to the Alpha-7 and
prints a calibration report if desired.
This library contains the “Tree Control”for the Alpha-7 Client and Calibration
Wizard.
This library contains the “Spectrum Control”for the Alpha-7 Client and
Calibration Wizard.
This library contains the “Dose Control”for the Alpha-7 Client.
This library contains the “Chart Control”for the Alpha-7 Client.
This library contains the RadNet properties dialog for the Alpha-7 Client.
This file saves the configuration settings on exit from the Alpha-7 Client.
Settings include window sizes, the instrument list, spectrum zoom settings and
refresh time, chart settings, and dose control column widths, etc. The file can be
deleted if some settings become unresponsive or unworkable. If deleted, the
Alpha-7 Client will create a new file on the next exit.
Typical Alpha-7 Client directory structure:
\PROGRAM FILES\
EBERLINE\
A7CLIENT\
A7CALIB.EXE
A7CLIENT.EXE
A7CLIENT.A7C
A7SERVER.EXE
RADNETSVR.EXE
CHART.DLL
DOSE.DLL
RADNETUI.DLL
SPECTRUM.DLL
TREE.DLL
REGA7.BAT
UNINSTA7CLIENT.ISU
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Software Updates
The Alpha-7 has the ability to automatically install and register software updates. The user
simply copies the updates from the distribution source into the C:\Eberline\Alpha7\Updates
folder in the Alpha-7 hard drive. When the Alpha-7 is started or re-started, it first checks to
see if a software update is available by checking the Updates\ folder for any *.exe, *.dll, or
*.bat files. If there are updates, it moves the newer files to the active Alpha7\ folder,
overwriting the existing files. The Alpha-7 Startup.bat file then runs the RegA7.bat file to
update any file registrations that may have changed with the updated files. The Alpha-7 then
initializes all the necessary files to start operation again. It is highly recommended that the
software running on any PC used as a client for the Alpha-7 be updated at the same time as
the software on the Alpha-7. Alpha-7 Client applications that have not been updated may
continue to run normally but will not implement any new features or corrections that have
been made.
To update client installations, the user may simply run the Alpha-7 Client CD, which will copy
all the distribution files onto the installation target and register the files. Alternatively, simply
copy the new executable and library files provided for the update (.exe and .dll files
respectively) to the current directory for the client software and run the RegA7.bat file. This
process insures that new features and corrections will be available. This process is also
valuable if the user is unsure of the current version on the Alpha-7 in question. The user may
copy the files listed above from the Alpha-7 to the client Alpha7 folder (usually C:\Program
Files\Eberline\Alpha7) and run RegA7.bat. This insures compatibility with the existing
programs on the Alpha-7. It is highly advisable to update all Alpha-7s and clients whenever
an update is available, to take advantage of any new features which may have been added.
NOTE: The RegA7.bat file insures that all the files are properly registered with the
operating system and relies on the REGSVR32.EXE file provided with the Microsoft
Windows version running on the client computer. If your computer uses nonstandard directories for its Windows software, please contact Thermo Eberline or your
system administrator for assistance in obtaining a RegA7.bat file customized to
correctly update your system registry.
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Alpha-7 Hardware
Single Board Computer (SBC)
The Alpha-7 uses a small, PC-compatible single board personal computer (SBC) for the main
processing and calculations. Because of the constant advances in SBC technology, and in
particular in microprocessors, the single board computer in the Alpha-7 may have different
specifications that those listed in this manual. Externally, the SBC is identical in each of its
versions. There are no user-serviceable parts inside the case of the SBC.
Display Board
A front panel display board controls the alarm annunciation and relays, analog output and the
vacuum fluorescent display. This board is powered by an 8051-family 8-bit microprocessor. It
provides the interface for the SBC to the external indicators, the Alarm Ack. button and door
switches. The communications link with the SBC is via an RS-232 serial communication port.
The second port is an RS-485 port and provides the serial communication link between the
Display Board and the Multi-Channel Analyzer (MCA) Board.
The front panel Display Board also controls the relays for external signals from the Alpha-7.
On the Alpha-7L, an eleven-pin MIL-spec connector provides access to the loop-powered 420 milliamp output and the alarm, trouble and failure relay contacts.
All other relay connections are accessed on screw terminals behind the black cover plate on
the left side of the display unit. Terminal definitions may be found in the Drawings section of
this manual.
Multi-Channel Analyzer (MCA) Board
The MCA Board is mounted in the remote sampling head enclosure. This board provides all
the functions required for multi-channel analysis, including signal conditioning, peak trapping,
and analog to digital conversion. The amplitude of each pulse is digitized and the
corresponding channel counter incremented to create the spectrum.
A mass flow sensor is used to accurately measure the volume of air passing through the filter,
providing the additional information needed to determine concentrations. A separate preamplifier board, mounted on the detector itself, provides the interface to the detector.
Communications between the Display Board and the MCA Board in the remote head is
performed via a high-speed serial communications link over an RS-485 connection. The
RS-485 configuration is capable of supporting distances of up to 500 feet using 22 AWG
wiring and allows remote placement of the head.
These subassemblies are described in more detail in the Hardware Description section of this
manual.
9
Theory of Operation
Technological Advancements
The Alpha-7 uses peak shape analysis to determine the activity of specific isotopes on the
filter paper. This is a new approach replacing the older methods using regions of interest
(ROI’s) or exponential tail fits. The advantage of the technique is the ability to accurately
determine the amount of an isotope interfering with the measurement of the isotopes of
interest.
For example, because Pu-239 is on the tail of one of the radon daughters, it is very important
to be able to subtract those counts in the Pu-239 region caused by the radon daughters. The
older technique relied on factors used to subtract a portion of one ROI from another. The
factor was not constant, however, and depended on the age of the filter (as radon daughters
were collected and came into equilibrium), dust loading, and detector quality. The new
technique used in the Alpha-7 is much more accurate at measuring the interference from the
naturally occurring isotopes and performing the background compensation. This method also
allows for automatic gain adjustment to constantly insure that the reference peaks are aligned
with the proper energy.
The curve fitting is performed using a proprietary peak shape model and iterative algorithm
developed by Thermo Eberline specifically for the Alpha-7.
The MDC is calculated from the variance in the curve fit. This provides a better estimation of
MDC than the older method using ROI’s, which depended on the accuracy of multiple regions
of interest. The MDC calculation takes into account both the variability in the measurement of
the counts, which is minimized due to the curve fit, and the variability due to the curve fitting
process itself.
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Spectrum Measurement
Spectrum Acquisition
The Multi-Channel Analyzer (MCA) Board contains a 12-bit digital-to-analog converter (DAC)
that provides for energy resolution of up to 4096 channels. The Alpha-7 uses a 512-channel
configuration for an energy resolution of approximately 20 KeV/channel. The spectrum
counts are kept in an array of four-byte counters which support up to 4.3 billion counts per
channel. On start-up or after a filter change, a Reset Spectrum message is issued to the
MCA Board, followed by a Start Count message. Counts will continue to build the spectrum
until the next filter change or a manual spectrum reset from the Alpha-7 Client.
Once per second, the A7Server program polls the spectrum from the MCA Board and
calculates a “best fit”of individual isotope peaks, where the summation of the peaks provides
a minimum “least squares”difference between the actual channel counts and the fitted curve.
The individual isotope peak curves are saved and may be viewed from the Alpha-7 Client
program by selecting the isotope in the Tree Control. Selecting the instrument icon in the
Tree Control provides a view of the overall fit.
The resulting curve fit coefficients provide values that represent the total counts under each
isotope peak, along with a derived count variance that is used to determine the minimum
detectible activity/concentration for each peak.
Peak Shape Factors
Several factors affect the shape of the individual isotope peaks— thereby, the sensitivity of the
instrument:
Detector to filter paper distance— As an alpha particle travels through air, the decay energy
of the particle is depleted (i.e. attenuated) by collisions with air molecules. This means
that a 6.00 MeV alpha emitted by a Po-218 decay, may reach the detector with only 5.50
MeV. This energy attenuation means that the distance between the detector and the
surface of the filter paper has a dramatic effect on the peak width, and thereby, the ability
of the instrument to accurately resolve isotopes near the 6.00 MeV Po-218 radon
daughter peak. This effect can be noted when comparing the spectrum from the In-Line
Remote Head (which has a 4.3mm spacing), and the spectrum from the Radial Entry
Remote Head (which has a 6.3mm spacing).
Altitude and Barometric Pressure— Like the detector to filter paper distance effect, the
density of the air in the detector/filter gap will change with increases/decreases in
barometric pressure due to meteorological conditions or changes in altitude. Less dense
air means fewer collisions and less alpha energy loss on arrival at the detector. For this
reason, the Alpha-7 must be calibrated at the altitude where the instrument will be
installed— preferably during a time of average barometric pressure for the region. In spite
of these precautions, some peak broadening may be observed as low or high pressure
fronts move through the area.
Filter Paper Type— The type of filter paper used can also affect the peak shape. Rough or
paper-type filters have holes and pits where particles can become deeply embedded and
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the resulting alpha-emissions experience significant energy loss as they work their way
out through layers of dust and filter fibers before finally reaching open air. For best peak
shape, use a filter paper with a very smooth surface. Thermo Eberline recommends the
5-micron Teflon-membrane Fluoropore filters (Catalog number SA1J408V2) for their
superior performance in peak shape while maintaining a low pressure drop.
Filter Loading— As the accumulation of particulates on the filter progresses, previously
deposited particles will become buried by more recent deposits, further degrading the
energy reaching the detector. This effect causes peaks of isotopes with longer half-lives
to shift towards a lower energy as the emitted alphas can lose significant energy before
even reaching open air.
Curve Fitting
General Algorithm
The Alpha-7 utilizes a sophisticated algorithm for determining the concentrations of alphaemitting isotopes. Whereas, most Alpha-CAM’s use a region-of-interest approach for
measuring total counts within energy ranges, the Alpha-7 uses information about the peak
shape to mathematically separate the spectrum into a combination of individual isotope
peaks. The curves from these individual isotope peaks, when summed, produce a “fit”of the
total spectrum. The quality of this fit is the primary determinant of the instrument sensitivity.
In a radon background, the best sensitivity to mid-energy isotopes will be obtained when the
peak shape factors listed above are minimized to produce narrow peaks and the model
closely fits the tail shape of the 6.0 MeV Po-218 peak.
Studies of Alpha spectroscopy have yielded several generalized mathematical models to
describe the shape of an air-attenuated alpha peak. To represent peaks in the Alpha-7,
Thermo Eberline has developed a model which best fits the spectrum data acquired by the
Thermo Eberline detector and electronics and easily adjusts to different filter types and
detector spacings.
As mentioned above, a new spectrum is acquired every second and peak areas (counts)
derived based on fixed peak-shape coefficients. Once every fifteen seconds, the program
checks the peak-shape coefficients to make slight adjustments for any changes in the peak
shape.
Obviously, the algorithm to determine curve fit is quite numerically intensive and consumes a
good percentage of the available processing time of the SBC. Computation time increases
exponentially, as the number of peaks that are to be fitted increases. For this reason, it is
important to include in the Alpha-7 isotope tree only those isotopes that the user wants to
measure or expects to be present in the sampled air.
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Peak Shape Training
Since the instrument is normally used at a fixed altitude, with a certain type of filter paper, and
in a fairly fixed set of environmental conditions, the peak shape— over the first 24 hours— will
rarely change visibly. However, if the MCA electronics or the detector is changed out during
maintenance, or if a different filter paper type is installed, the peak shape can change
significantly.
The Alpha-7 program incorporates code to “train”itself to the peak shape it typically sees. To
allow the instrument to train itself to its typical operating conditions, a 24- to 48-hour trial
should be run prior to putting the instrument into use to allow the training algorithm to
measure and store the ‘typical’shape parameters. The shape parameters will be saved when
the total counts are greater than 16,000 and the Fit Ratio (see below) drops below 0.60. If this
trial run is not possible, it should be noted that the instrument will still be operational, but may
not have the optimal sensitivity it would have if ‘trained’properly.
Curve Fit Statistics
The Spectrum Ciew in the Alpha-7 Client provides some indications of the quality of the curve
fit. If Statistics are enabled, the upper left corner of the spectrum display will show three
values which apply to the fit: Total Counts, ChiSq and Fit Ratio.
Total Counts— indicates the total number of alpha counts in the spectrum. When there are
few counts in the spectrum, the curve fitting results are more inconsistent, but as counts
increase, the individual peaks become more obvious and the curve fit is accomplished
more rapidly and accurately. At 8000 counts in the spectrum, there is usually enough
information to begin determining the peak shape coefficients and so the customer may
notice gradual changes in the fit at this point. While there is no definite crossover point in
the total counts, by the time the spectrum has 80,000 counts, the curve fit should be quite
accurate.
ChiSq— is the Chi-squared value that represents the sum of the squares of the deviations
between the actual channel counts and the curve fit counts. This value can be expected
to increase as the total counts increase.
Fit Ratio— is a calculated value which best describes the quality of the curve fit. The value
changes during the life of the filter buildup, usually starting out about 1.5, then dropping
over the next day to below 0.6, then gradually increasing again. Values greater than 2.0
are cause for attention and the spectrum should be examined for signs of unlisted
isotopes, spectrum noise or unusual filter buildup.
Curve Fitting Difficulties
While the algorithm is quite robust and can adapt to significant changed in peak shape, the
curve fitting can fail if not all isotopes being collected on the filter paper are present in the
Alpha-7 isotope tree, if the unit has been miscalibrated, or if unusually heavy filter loading has
occurred. In this case, the instrument will enter a failed condition with a status of “POOR
CURVE FIT.” An examination of the spectrum may provide an indication of the cause.
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To clear this condition, the user must change the filter, issue a Reset Spectrum command
from the Alpha-7 Client or, as a last resort, re-calibrate.
Concentration Calculation
Fast and Slow Integration Windows
Each isotope measured by the Alpha-7 uses two integration times, which are independently
set for each isotope. This means that a longer time can be used for isotopes expected to have
low concentrations and shorter integration times for those isotopes expected to have higher
concentrations. These are described as Fast and Slow Window intervals.
The default values are 60 seconds and 30 minutes. In the case of the default values the fast
alarms are evaluated each second based on the most recent two 60 second intervals and the
slow alarms are evaluated every five seconds based on the most recent two 30 minute
intervals.
The MDC for longer window times will be lower because it has better statistics resulting from
longer effective count times. The statistical fluctuation will also be less for longer window
times.
The Alpha-7 will start monitoring the concentration after two seconds (two fast interval
updates) and the flow is above the flow fail limit value specified in the sample flow properties
window.
History Arrays
The A7Server program keeps a history array of count rate, variance, flow and volume
readings for each isotope, in both one-second detail (for determining fast concentration) and
one-minute detail (and slow concentration). A maximum of 20 minutes of one-second detail
are retained, while the one-minute detail is limited to 8 hours.
Concentration Calculation Method
The curve fit function produces coefficients for each isotope that correspond to the counts
under the peak. In order to calculate a concentration, the counts for each peak are saved—
along with the flow rate and volume— in a history array, so that the increase in counts over
time can be used to determine the net count rate. For each isotope, two different time
intervals are used to determine concentrations and are referred to as the “fast window”and
“slow window”times (sometimes called ‘acute’and ‘chronic’). The peak counts— based on the
history values over one and two window times— are used to determine the net count rates.
For instance, if the window time is 60 seconds, then the net count rates for the previous
minute and also the minute previous to it, are calculated. For long-lived isotopes, the
difference in net count rates over the two intervals is proportional to the concentration. Once
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the change in net count rate is known, the calibration constant and flow volume are used to
derive the concentration in the specified measurement units.
An additional term is included in the concentration calculation to account for the expected
count rate losses due to activity that has decayed off during the last interval. For longer halflived isotopes the term Net0 ? goes to zero. However, this term is very important for the
proper treatment of the short-lived radon daughters.
It should be noted that in situations where the counts under a peak are changing very slowly
or not at all, slight variations may occur in the determination of the net count rate, which can
result in small negative concentrations. The Alpha-7 reports negative concentrations as “< 0.”
This is an indication of no appreciable airborne concentration. These effects are minimized
by the use of the two different evaluation intervals, with a longer interval providing greater
precision in low-level measurements.
Concentration Equation
The concentration equation used for the fast and slow calculation is:
Concentration ?
?? Net1 ?
Net 0 ? / TWA ? Net 0 ? ? ?
Yield
Vol Sample ? K DAC ? Cal ? Eff
Where,
1
TWA = Actual slow/fast window time in seconds
Net0 = Net count rate from T – 2TWA to T – TWA
Net1 = Net count rate from T –TWA to T
Cal = Calibration constant
Eff = Detector efficiency (4-Pi)
Yield = Isotope Alpha yield
VolSample = Sampled volume since filter change
KDAC = DAC conversion factor (equals one if DAC not used)
? = decay constant, ? ?
ln ?2 ?
where, T½ = isotope half-life
T½
A mass flow sensor is used to accurately determine the volume of air collected on the filter
paper during the count time.
1
The actual window time may be shorter than the user-defined window time. When a new spectrum is begun, following a
spectrum reset or a filter change, a window time equal to the elapsed time, is used so that a “best guess”concentration value
can be calculated. This actual window time will increase until it is equal to the user-defined time. This occurs when the userdefined window time has elapsed since the filter change or spectrum reset. After this point, the user-defined time is used.
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Dose Calculation
The Alpha-7 program calculates dose according to the activity collected on the filter paper.
Because the Alpha-7 is typically used to continuously monitor the air in a facility, the concept
of “worker dose”is dependent upon the portion of time the worker spends in the facility in
comparison to the time the Alpha-7 filter has been accumulating activity. For instance, if an
Alpha-7 has been sampling air at 1 CFM for 40 hours, and the activity of Pu-239 is 15 dpm,
the worker dose is not 2 DAC-h, but is dependent on how much of the 40 hours the worker
spent inside the room being monitored. The determination of worker dose must be
accomplished administratively by noting the dose readings when the worker enters and
leaves the area and calculating the increase in dose.
Activity ?
Dose ?
Net1 ? Yield
TWA ? Cal ? Eff
Activity
?K DAC ? FlowSample ? 60?
Where,
1
TWA = Actual slow/fast window time in seconds
Net1 = Net count rate from T –TWA to T
Cal = Calibration constant
Eff = Detector efficiency (4-Pi)
Yield = Isotope Alpha yield
KDAC = DAC conversion factor (equals one if DAC/DAC-h not used)
Region of Interest Calculation
In addition to measurement of specific isotopes, the Alpha-7 program also supports the
definition and calculation of concentration of multiple isotopes within an energy Region of
Interest (ROI). The difference between the ROI calculation and the calculations for specific
isotopes, is simply in the computation of net counts within the region. These net counts are
then assigned to an isotope with a user-defined name, such as “Region”or “MixedU,”and
treated as if the counts were all under the same peak.
The ROI counts are calculated by summing the counts from isotopes whose peak is within the
bounds of the region, then adding the difference in counts between the curve fit and the
actual spectrum counts (summed over the ROI).
Error Handling and Exceptions
Due to a number of circumstances, a valid concentration is not always calculated during each
one-second interrupt. On entry into the concentration calculation function, the elapsed time
since the last calculation is checked to see if any updates were missed. If updates were
missed, the last good concentration value is used instead.
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Minimum Detectable Concentration Calculation
Uncertainties in Peak Counts
In most ROI-based Alpha-CAM’s, the minimum detectible concentration is based on the
statistical uncertainty of the background counts that fall within the region, in combination with
the uncertainty of any counts in excess of the background. In the Alpha-7, the minimum
detectible concentration (MDC) is not directly related to the spectrum counts, but to the
uncertainty in the curve fit.
When the curve fit is completed each second, several values are returned which represent
the counts under each peak. As described earlier, these values are statistically distributed
about the ‘true’peak areas and have known probabilities of being within 1-sigma, 2-sigma,
etc. of the true area. A characteristic of the curve fit algorithm is that in the course of solving
the minimization problem, a “covariance matrix”is calculated which described the errors
associated in the solution. This covariance matrix identifies, on its diagonal, the variances of
each coefficient— including the peak area coefficients. In other words, the curve fit routine
returns the actual variances for the peak areas so that uncertainties due to interfering isotopes
(I.e. background) have already been considered.
Although the actual calculation of the covariance matrix is too involved to describe here, an
examination of the peak area variances confirm that, for a well-defined spectrum (> 80,000
counts), when the counts due to an interfering isotope greatly outnumber the counts due to
the isotope in question, the variance increases. Likewise, when there are very few interfering
counts from other isotopes, the variance begins to approach a value equal to the peak area
counts.
In the case of a non-well-defined spectrum (< 80,000 counts), the curve fit solution is more
uncertain, and therefore, the uncertainties of the peak areas are understandably higher. This
means that as more and more counts are accumulated in a spectrum and the peaks become
smoother, the peak area uncertainties (hence, the MDCs) actually improve— in spite of
interfering counts!
Calculation of the Variance of Net Count Rate
The variances returned from the curve fit routine represent the uncertainties on the total peak
counts for each isotope. These values, however, cannot be used directly in the determination
of the MDC, since the MDC calculation involves net count differences in the peak area.
Typically, the variance of a difference is simply the sum of the individual variances, but with a
continuously growing spectrum, we do not have independent measurements of the peak area.
Because each spectrum is dependent on the previous spectrum (i.e. the counts in each
channel can never decrease, but are dependent on the counts that had already accumulated
in the previous measurement), we use a different approach to calculating the “net”variance.
In repeated measurements of a growing sample, we can determine an average variance by
taking the total variance and dividing by the number of samples. In the case of the Alpha-7
spectrum, we take the variance for each peak and divide by the total spectrum counts to get a
variance-per-total-count average (V). The sum of the averages at the start and end of a
window interval, when multiplied by the increase in total counts over the same interval, yields
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the variance of the net counts for that window period. The square root of the sum of the
previous and current window variances then produces the standard deviation of the net count
increase/decrease in activity (in counts).
What remains is simply to apply the flow, calibration constant and efficiency factors to the
standard deviation in counts to convert to the units of concentration. The final MDC
calculation, then, is as follows:
Variance0 ? NetTotal 0 ? ?V2WA ? VWA ?
Variance1 ? NetTotal1 ? ?VWA ? VCur ?
Sigma ?
Variance1 ? Variance0
? ? Variance0
TWA
K ? Sigma ? Yield
Cal ? Eff ? Vol Sample
MDC ?
Where,
K = false alarm rate factor (i.e. Sigma Factor)
NetTotal1 = Increase in total spectrum counts in most recent TWA
NetTotal0 = Increase in total spectrum counts in previous TWA
Region of Interest MDC
The variance for the region of interest is calculated differently. The ROI variance is the sum
of the individual variances (per total count) of the isotopes within the region, plus the
covariances (per total count) between the isotopes within the region (these can be negative),
plus the variance (per total count) due to the difference (in counts) within the region between
the spectrum and the curve fit.
V ?
?
V ?
iso
ROIisotopes
?
Co variso ?
ROIisotopes
? ?Spect
ch
? Fitch ?
ROIchannels
NetTotal1
This variance is then archived in the history array and represents the VCur, VWA and V2WA
variances in the equations above.
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Alarms
Once calculated, the concentration levels are compared against the appropriate alarm levels,
and an alarm occurs if the calculated level is equal to or exceeds the alarm level. The fast
concentration alarm is used to give rapid alarm response on high (acute) concentrations. The
slow is used to accurately measure lower (chronic) concentrations. For both Fast/Slow
Window integration times, until one full interval has passed, the alarms will be evaluated
based on only elapsed time. Once a full interval has elapsed that particular alarm will be
evaluated based on the specified evaluation time.
NOTE: If an alarm is below the currently calculated MDC (Minimum Detectable
Concentration) the alarm is temporarily set to the MDC. This helps prevent nuisance
alarms caused by poor statistics at very low concentrations combined with very short
evaluation intervals.
As the filter loading changes, especially as the radon daughters are collected and during their
equilibration, the MDC for each isotope will change, generally decreasing up through a period
of twice the evaluation interval selected, then increasing gradually to reflect the impact of the
variability associated with the increased total counts. The Normal LED on the front panel will
blink as long as any alarm set points are below their respective MDC.
20
Configuring Your Alpha CAM
Network Setup
NOTE: The Alpha-7 can be operated either as a stand-alone instrument, or as one of
multiple instruments on a network. In either case, the Alpha-7 is shipped “network
ready” so that it can be configured from a networked PC or laptop computer. If you
intend the Alpha-7 for stand-alone operation and will set up the unit using an attached
monitor, keyboard and mouse, then you may skip to Local Setup Using A Monitor And
Keyboard.
CAUTION: Network setup can be very complicated. For this step of the Alpha-7 setup,
you may wish to request the help of your network administrator.
In order to communicate with another computer, either the Alpha-7 settings must be changed
to be compatible with the other computer, or the network settings of the other computer must
be changed to be compatible with the Alpha-7. To set up the Alpha-7 for use on a TCP/IP
network, the following information must be obtained from your network administrator:
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Network Setting
Required Setting
Eberline Default
Setting
Computer Name
Uses static or
dynamic IP address
TCP/IP Address
(or Address Range)
TCP/IP Subnet
Mask
Gateway
Editable through
Calibration Wizard
A7000xxx
static
Yes
No
128.0.0.xxx
where xxx is listed
on the calibration
sheet.
255.255.0.0
Yes
128.0.0.1
No
Yes
The Alpha-7 comes pre-configured from the factory with a static IP Address and Computer
Name based on the serial number of the instrument. This data is printed at the top of the
calibration sheet for each Alpha-7.
The Alpha-7 Calibration Wizard allows configuration of only the IP Address, Subnet Mask and
Computer Name. After conferring with the network administrator, if any additional network
settings must be changed, the Alpha-7 setup will require local modification using a monitor
and keyboard (see following section).
When performing remote setup from another computer on an existing network, or over a
simple two-computer network using a “cross-over”Ethernet cable to directly connect the
computer with the Alpha-7, the computer used must have an IP Address and Subnet Mask
compatible with the default values in the Alpha-7. Once the any of these parameters have
been changed, the Alpha-7 must be restarted for the changes to take effect (see Routine
Operation And Maintenance— Power Down).
Local Setup Using A Monitor And Keyboard
For stand-alone use, the Alpha-7 can also be configured by connecting an SVGA-compatible
monitor, a keyboard and a mouse (using the supplied Y-adapter) to the PS2-style connector
on the Alpha-7 SBC. This is very useful if no network connection is available. These
connectors are accessed on the right side of the display unit (see Drawings— Alpha-7 Outline
Drawing).
The user can either modify the network parameters using the Microsoft Windows methods, or
run the Alpha-7 Calibration Wizard locally and use the editing capabilities in the Instrument
Properties dialog.
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Please note that the Alpha-7 Calibration Wizard may not be installed on the Alpha-7 itself for
security reasons. This means that network setup must be performed using the Microsoft
Windows Network Properties dialog. Again, the Alpha-7 must be restarted if any changes are
made to the network parameters.
Network Setup Using The Alpha-7 Calibration Wizard
For security reasons, critical Alpha-7 setup options must be accomplished through the
Alpha-7 Calibration Wizard. This program, which is covered in much more detail in the
Alpha-7 Calibration section, enables additional functionality in the Tree Control than is
enabled by the Alpha-7 Client program.
Alpha-7L Specific: To run the Alpha-7 Calibration Wizard (A7Calib.exe), it will need to
be installed in the Alpha7 folder of the client PC or the instrument itself. The Alpha-7
Calibration Wizard program is not included in the Alpha-7 Client Installation CD. It
must be copied from the Alpha-7 Calibration Wizard distribution diskette to the client
folder (typically C:\Program Files\Eberline\Alpha7).
Run the A7Calib.exe program from the client folder. The initial Wizard Page will appear
which can be skipped by clicking Next.
On the Instrument Information and Isotope Configuration page, fill in the Instrument Name
field and click the Connect button. The Tree Control should indicate “Trying… ,”then display
the instrument icon when the connection is completed (this can take up to 90 seconds). Next,
right-click on the instrument icon to get the instrument pop-up menu and select Properties…
Under the General tab, enter the Instrument Location text, the new Computer Name, IP
Address and Subnet Mask, then click the OK button. To finalize the network changes, right
mouse click on the instrument icon again and select Restart… The Alpha-7 will do a
shutdown and restart. When it finishes restarting, the new network settings will be in effect. At
this point the network configuration is complete and you may Cancel out of the Calibration
Wizard, and, if necessary, reconfigure the network settings of your client computer to be
compatible with the new settings of your Alpha-7.
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Setup Using The Alpha-7 Client
Most of the remaining instrument setup can be accomplished using the Alpha-7 Client
program. This program contains the same Tree Control used to configure the network
parameters described under the Alpha-7 Calibration Wizard section. The Alpha-7 Client
program is initiated by double clicking on the Alpha-7 Client icon on the Windows desktop, or
by double clicking on the A7Client.exe file in Windows Explorer.
Password Access
Two levels of password access are provided in the Alpha-7 Client program. The first level
provides the user View-Only access. The second level provides editing capabilities to
configure the Alpha-7, but does not allow modification of any information that would effect the
instrument calibration. Those modifications are restricted to the Alpha-7 Calibration Wizard,
which provides a third level of access via administrative control of the program availability.
The Tree Control in the Alpha-7 Calibration Wizard allows unrestricted editing of all Alpha-7
parameters.
When the user starts the program, a password screen will be presented for the user to enter
the appropriate password. There are two levels of password access: View-Only and Full
Rights.
Entering the View-Only password allows the user the lowest level of access to the client
program. The user may view the Alpha-7 operating parameters and data but is not allowed to
change any values or configuration. In this mode most parameter fields will display the
settings, but the edit field will be grayed out preventing user modification. The default ViewOnly password is blank, which means you can press the Enter key or click OK with the mouse
to enter the client.
Entering the Full Rights password allows the user access to configuration parameters for all
Alpha-7 instruments that can be accessed from that client computer. These changes include
the instrument name, display page settings, isotopes to be measured, and alarm set points.
The user is not allowed to change any of the calibration data that might affect the quality of
the measurement using this program. The default Full Rights password for all new Alpha-7
Client installations is “eberline”. The password is case-sensitive, so be sure that the Caps
Lock is off.
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The View-Only and Full Rights passwords can be edited by clicking on the Edit menu item in
the Alpha-7 Client and selecting Passwords… . Password editing is limited to users who log
on with the Full Rights password. The user may then change both the View-Only and Full
Rights passwords.
Care should be taken to properly document the passwords when they are changed. If the
passwords should be lost, access to the program can only be regained by uninstalling the
program and reinstalling it to restore the default passwords.
Keep in mind that the passwords are independent for each installation of the Alpha-7 Client,
and unless the passwords are set the same for multiple installations, the password for one
installation will not be accepted at another installation on a different computer.
The third level of security for modifying calibration data is provided administratively by
restricting access to the Alpha-7 Calibration Wizard software. The calibration software is the
only method for modifying the Alpha-7 calibration data and network settings. Data may be
modified manually if necessary, but use of the automated calibration wizard is advised for
both ease-of-use and accuracy of calibration.
Alpha-7 Client Overview
The Alpha-7 Client program is the primary user interface for the Alpha-7. It provides all of the
information access functions and the more common instrument maintenance functions.
There are four main sections to the display - three of which can be displayed at any one time.
The four are the Tree Control showing the Alpha-7 instruments available on the network, the
Spectrum Control showing the total counts plotted in a bar chart format by energy, the Dose
Control showing the DAC, DAC-h and concentrations for the isotopes selected by the user
and a strip Chart Control which graphically depicts the value for the selected isotopes
referenced against the alarm set point for that isotope.
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The Tree Control is always shown on the left side of the Alpha-7 Client display. The screen
image below shows the Spectrum Control in the upper right portion of the screen and the
Dose Control in the bottom right portion. The Chart Control can be selected by using the pulldown menu for View, or by clicking on the appropriate tool icon in the Alpha-7 Client toolbar.
The Chart Control, Dose Control, and Spectrum Control may be displayed in either the upper
or lower window. The three icons on the left end of the toolbar select the control to be shown
in the upper right window, while the three icons on the right end of the toolbar select the
format to be displayed in the lower right window. Each of the windows can be resized using
normal Microsoft Windows drag and drop methods.
The Tree Control is used to select which instrument’s data is displayed in the other windows.
When either an instrument or one of its isotopes is selected, the controls in the right hand
windows will display data for that instrument.
For the, When an isotope is selected in the Tree Control, the Alpha-7 Spectrum Control will
show the curve fit for the selected isotope as a red line drawn over the spectrum in the
position of the selected isotope. When the instrument is selected (i.e., click on the instrument
icon), the entire curve fit (of all isotopes) will be shown drawn in red onto the spectrum.
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Isotope Database
The Isotopes.mdb database provides the isotope references for the Alpha-7. A default
database is supplied by Thermo Eberline containing the most common isotopes of interest,
including the radon progeny and a mixed-uranium region of interest. The user can add any
desired isotopes to the Alpha-7 by adding the necessary data into the Isotopes.mdb database.
The Alpha-7 will then allow the newly added isotopes to be added to the tree. This database
is stored directly on the Alpha-7 in the Data/ subfolder, and is valid only for the Alpha-7 on
which it resides.
Once the database has been edited, it can be copied to any other Alpha-7 to standardize the
operation. This must be performed as a manual operation, since the database is not updated
automatically by the startup process.
The Isotopes.mdb database consists of the following fields:
ID
The entry number in the table, usually generated automatically
Isotope
The isotope name as desired to appear in the Alpha-7 tree and controls,
limited to 8 characters
Parent
A check box indicating that this isotope is the start of a user defined decay
chain, and will appear in the list as a parent isotope
Energy1 (MeV)
The weighted peak energy of the alpha particle(s) emitted from this
isotope2
Particulate
A check box indicating that this isotope is particulate in nature and will be
collected on the filter paper
Alarms
A check box indicating that the default condition for this isotope is alarms
are enabled when added
Reference
A check box indicating that this isotope will be used as a reference for the
auto energy alignment function. These are usually the normally occurring
radon progeny, but in the case of filtered air, they may include the main
isotope of interest
DAC Unity
This value is the conversion factor from uCi/cc, which are the default units
for an added isotope, to DAC. If the default units are changed from the
client program, the DAC unity value must also be changed to match the
new units.
Half-life (sec)
This is the half-life of the isotope in seconds
Daughter1
The first decay product of the isotope
Abundance
The abundance of the first daughter product
2
The energy of an isotope with multiple decay paths may be calculated by “weighting”each energy by the associated
abundance. For instance, the weighted energy of an isotope with two alphas; one of 75% abundance at 4.6MeV, and one of
25% abundance at 4.53MeV, can be calculated as E = 4.6 x 0.75 + 4.53 x 0.25 = 4.5825 MeV.
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Beta
A check box indicating whether this daughter was produced by a beta
decay, which would not produce a measurable event for the Alpha-7
Stable1
A check box indicating that the result of the decay of the isotope is a
stable isotope
Daughter2
The second decay product of the isotope (not currently used)
Abundance2
The abundance of the second daughter product
Beta2
A check box indicating whether this daughter was produced by a beta
decay, which would not produce a measurable event for the Alpha-7
Stable2
A check box indicating that the result of the decay of the isotope is a
stable isotope
Page
The default local display page for the isotope on the Alpha-7
Logging
A check box indicating the default logging status for the isotope when
added
Comments
A text space for a user-definable comment
The default energies for the alpha-emitting isotopes in the database are taken from the U.S.
Department of Health, Education and Welfare, Radiological Health Handbook. For isotopes
which had multiple alpha emissions, all emissions that were within plus or minus 3 percent of
the normal peak energy were combined together using a weighted average based on the
abundance of each energy peak to arrive at an average energy for the peak energy of that
isotope. None of the isotopes currently listed in the database have more than one major
peak, although the database is configured to support isotopes with multiple alpha peaks.
As of Version 1.6 of the A7Server program, second daughters of an isotope are not
supported.
Using The Tree Control To Set Up A CAM
Elements Of The Tree Control
The Tree Control is made up of three elements: the System Root icon and description, the
Instrument icon and description, and the Isotope icon and name.
The System Root is always present in the tree and
identifies the network type— in this case an Eberline
Alpha-7 System.
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Next is an Instrument icon and description. In the example below, there are two kinds of
Instrument icons and two types of descriptions. The top instrument is on-line and is indicated
by a standard icon with the monitor Location (ATCR 402) listed in the description field. The
next Instrument is off-line and is indicated by a “off-line”icon, preceded by a Fail Beacon
icon. The description field is the Computer Name assigned to the instrument. Individual
instruments must be added manually to the tree. There is no auto-search of a network to
identify Alpha-7 instruments.
In addition to the Fail Beacon icon, there are Alarm Beacon (red) and a Maintenance Status
(wrench and screwdriver) icon.
The last element is the Isotope icon and name. The list of isotopes in the tree corresponds to
the isotopes configured for the Alpha-7 under which they appear. The icons shown in the
example represent alpha-emitting isotopes. Beta-emitters, if present in the isotope list of an
Alpha-7, will have a different icon to distinguish them from the isotopes of interest. Isotopes
are added automatically to the tree when an Alpha-7 reports back the isotope list.
Tree Control Popup Menus
The three elements of the Tree Control each have a popup menu associated with them to
provide access to configuration functions. These menus are the System Menu, the
Instrument Menu, and the Isotope Menu. To activate each of the menus, place the cursor
over the tree element and click the right mouse button.
System Menu
Instrument Menu
Isotope Menu
System Menu
Adding Alpha-7s To The Instrument Tree
When the Alpha-7 Client is first installed, the Tree Control will not contain any instrument
icons. The Alpha-7 Client will not automatically search a network for Alpha-7 instruments and
add them to the tree. The user must add the instruments in his or her network to the Tree
Control before the icons will appear. Not all Alpha-7s need be added to the Tree Control.
Add only those instruments of interest to the user running the Alpha-7 Client.
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Instruments can be added by right-clicking the mouse on the “Eberline Alpha-7 System”entry
in the tree, producing the System Menu. When Add Instrument… is selected, a dialog box
will appear in which the Computer Name (or TCP/IP Address) of the Alpha-7 to be added can
be typed. Click OK and the Alpha-7 Client will add the specified Alpha-7 to the Tree Control
and attempt to communicate with it.
When an instrument is added, the Computer Name specified will be appear in brackets in the
instrument tree with a Off-Line icon next to the name. When the Alpha-7 Client attempts to
communicate with the Alpha-7, the name will be replaced with the text, “Trying… ”while
communications are established.
NOTE: For newly added instruments, this attempt may take as much as 90 seconds
before returning. Subsequent attempts should take only a second or two.
When communications with the Alpha-7 are established, the icon will change to a colored
Operational instrument icon and the instrument text will display the Instrument Location
description. Clicking on the “plus”symbol in front of the icon will expand the instrument tree
to display the Isotope List.
If communications with the new instrument cannot be established, the Off-Line icon will
remain and the Computer Name in brackets restored after the communications attempt.
There can be several reasons why the Alpha-7 is not accessible from the client computer.
Placing the cursor over the icon or Computer Name of the Alpha-7 will provide a “tool tip”
which will indicate the cause of the failure. If the “server is not available”tool tip appears, the
cause may be that the Alpha-7 is not turned on, is not accessible via the current Ethernet
network connection, or is incompatible with the current IP address or subnet mask.
Clock Synchronization
The System Menu can also be used to synchronize all Alpha-7s that are currently
communicating with this instance of the client program. Selecting Synchronize Clocks will
cause all the Alpha-7s in the tree to be set to the same time as currently being used by the
Alpha-7 Client computer.
Showing/Hiding Beta Isotopes
Checking or unchecking the Hide Beta Emitters menu selection can change the expanded
appearance of the tree. If this item is selected, isotopes with only beta emissions will not be
shown in the expanded tree even though they may be naturally occurring daughters of the
parent isotope.
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Instrument Menu
Pump On
Checked if the instrument currently has air flow. Normally
grayed-out. Active only during sample flow simulation.
Acknowledge
Alarm
Performs the same function as pressing the Alarm Ack.
button on the Alpha-7 Display Unit.
Synchronize Clock
Synchronizes the clock on this instrument only
Delete Instrument
Deletes the instrument from the tree
New Isotope…
Allows the user to add a new Isotope or Region of Interest to
the instrument. See Adding Isotopes and Adding a Region of
Interest
RadNet Config…
Presents a dialog to allow configuration of RadNet
parameters. Not active if RadNet is not enabled on the
Alpha-7
Properties…
This item calls up the Instrument Properties dialog described
in the next section.
Power Down…
This function does a remote Windows Shutdown of the
instrument.
Restart…
This function does a remote Windows Restart of the
instrument.
Tool Tips
The Tree Control also supports “floating tool tips.” For example, putting the cursor over an
instrument icon will display the current status of the instrument. In this case the Alpha-7 is out
of service (as indicated by the blue icon) because of a Flow Failure. This is shown in the
floating box below the monitor in the screen capture shown below.
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Holding the cursor over one of the isotopes being monitored provides the current isotope
status, Fast and Slow readings. This is much faster than changing the display between Fast
and Slow tables in the Dose Control.
Alpha-7 Instrument Parameters
To change the measurement parameters for the Alpha-7, right-click on the Alpha-7 that you
would like to work with and select Properties… .
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This dialog box provides information on most of the Alpha-7 general operating parameters.
Additional parameters specific for each isotope are addressed in another screen described
later in this manual. Editing of most of these parameters is restricted in the Alpha-7 Client
program.
Please be cautious in editing these parameters as the changes are made in Alpha-7 that you
are working with. In particular, please be very careful about the alarm levels and about
changing the units of the measurement. Changing the units should be done only during
calibration to ensure that the correct values and conversion factors are used. Values that are
grayed-out may only be changed using the Instrument Properties dialog in the Alpha-7
Calibration Wizard.
The tabs are:
General
Sample Flow
Release Flow
Analog Output
MCA
Versions
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General Instrument Properties
General is used to specify a location for the monitor as well as the monitor name and IP
address.
Location— is a descriptive name for the Alpha-7 which appears in the Tree Control and that
can be used to easily recognize the location, purpose or function of that specific unit.
IP Address— is the network address that the Alpha-7 will respond to via the Ethernet
connection. This network address comes set from the factory based on Thermo Eberline’s
testing network and may not be appropriate for the users network (to change, see Network
Setup). The last three digits are a function of the serial number, typically 100 plus the last 2
digits of the serial number. The user must modify the network address to conform to the local
network where the Alpha-7 is to be used.
Subnet Mask— is set to the appropriate value for the network. If you do not have this
information, please contact the person at your facility responsible for network administration.
The IP address and subnet mask shown above are for example purposes only and may not
be compatible with your network.
Computer Name— refers to the name that has been assigned to this specific Alpha-7 for a
network identifier. This name is shown on Page 0 of the Alpha-7 display during normal
operation. This same name or IP address is used to communicate with the Alpha-7 Client
program. When adding an instrument, the Computer Name is the name that is added to the
instrument tree.
Room Ventilation - Air Replacement— interval does not affect the measurement. It is used
to determine the equilibrium of radon daughters during isotope simulation. Isotope simulation
is available for each isotope in the tree and is intended for demonstration or training purposes
only.
Room Ventilation - Filtered Air— check box is used to select the time interval over which no
counts from the detector will cause an LOW COUNTS failure. If the Alpha-7 is measuring
filtered air, the radon background counts may be almost non-existent, hence, fewer counts will
be detected. The un-checked (non-filtered air) default interval is 10 minutes. If the box is
checked, the time period for a LOW COUNTS failure to occur is zero counts in three hours.
Sample Flow Properties
The Sample Flow page is used to enter flow action level limits for the High Flow, Low Flow,
and Flow Fail conditions. High/Low Flow statuses may be alarmed conditions or only
warnings, depending on the customer-requested factory settings.
High Limit— defines the alarm/warning level where a HIGH FLOW status will be annunciated
when the measured flow exceeds the limit.
Low Limit— defines the alarm/warning level where a LOW FLOW status will be annunciated
when the measured flow falls below the limit.
Fail Limit— defines the level where a FLOW FAIL status will be annunciated when the
measured flow falls below the limit. This is a failure condition and the unit will be taken out of
service.
Any individual action level can be disabled using the Disabled check box.
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Display Page— entry selects the “page”of the two-line Alpha-7 display on which sample flow
data will appear. In the example, the Display Page is set to Page 3, which will cause flow
data to appear on the third page that is displayed when the Alpha-7 display is scrolled from
the General Status Page on Page 0. Note that the flow value displayed is an average. The
averaging interval is adjusted using the Window (sec) slider immediately below the selection
box for the display page. A new flow measurement is made every second, and the display
value is then calculated by averaging the last x values together, where x is the number
indicated by the slider pointer.
NOTE: The following values may only be edited using the Alpha-7 Calibration Wizard.
3
3
3
3
Units— are shown in a pull-down list and include m /min, m /sec, ft /min, cm /min, and
liters/min. The selected units will affect the units of isotope concentration (e.g. flow units of
ft3/min will produce concentration units of pCi/ ft3, where the isotope units of measure are
pCi).
Max Scale and Min Scale— values in the A/D Conversion windows define the span for the
flow readings. The sample flow signal from the mass flow sensor is scaled by these values
to indicate the flow measured during calibration. These values are derived during flow
calibration and are set automatically by the Alpha-7 Calibration Wizard.
For simulation, or in the event of a failure of the mass flow sensor, the Alpha-7 can be
temporarily set for a simulated fixed flow. This is selected using the edit field and check box in
the Flow Simulation area in the lower left hand corner of the display.
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Use Fixed Flow— is a checkbox to enable the use of fixed flow. When this box is checked,
the Alpha-7 status will remain in a “flow failed”status until the pump is turned on using the
Instrument popup menu provided by right-clicking on the instrument in the directory tree.
Clicking on the Pump On selection will alternately turn the pump on and off for simulation. A
checkmark next to the Pump On item indicates that the pump is currently on. This function
has no effect on any actual pump associated with the Alpha-7. It does replace the flow
sensing with a fixed number so the Alpha-7 does not record the actual flow value from the
flow sensor. The Pump On control may be performed from the Alpha-7 Client program.
Flow Rate— defines the flow, in the currently selected units, that is simulated when the Pump
On command is invoked.
Release Flow Properties
The Release Flow allows the Alpha-7 to receive input from an in-line airflow sensor in a stack
or duct. This external analog 0 or 4 to 20 mA logarithmic signal is interpreted as being
proportional to the flow rate through one duct or stack. The Alpha-7 then uses this signal to
correct for the ratio of the sample flow rate to the stack flow rate to accurately determine the
activity released from the facility.
The parameters on this page are very similar to those described in the Sample Flow
Properties section above. Unlike the Sample Flow Properties, the Alpha-7 does not provide a
Fail Limit for the stack release flow rate. This parameter is always shown in gray on the
display and can never be edited— even with the Alpha-7 Calibration Wizard.
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The Release Flow page is used to enter flow action level limits for the HIGH FLOW or LOW
FLOW conditions. High/Low Flow statuses may be alarmed conditions or only warnings,
depending on the customer-requested factory settings.
High Limit— defines the alarm/warning level where a HIGH FLOW status will be annunciated
when the release flow rate exceeds the limit.
Low Limit— defines the alarm/warning level where a LOW FLOW status will be annunciated
when the release flow rate falls below the limit.
Any individual action level can be disabled using the Disabled check box.
Display Page— entry selects the “page”of the two-line Alpha-7 display on which release flow
data will appear. In the example, the Display Page is set to Page 0, which will prevent
release flow data from being displayed. Note again, that like the Sample Flow reading, any
Release Flow value is an average. The averaging interval is adjusted using the Window
(sec) slider immediately below the selection box for the display page.
NOTE: The following values may only be edited using the Alpha-7 Calibration Wizard.
3
3
3
3
Units— are shown in a pull-down list and include m /min, m /sec, ft /min, cm /min, and
liters/min. The selected units will affect the units of Release Rate (e.g. flow units of ft3/min will
produce Release Rate units of pCi/ min, where the isotope units of measure are pCi).
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Max Scale and Min Scale— factors for the stack flow rate are edited in the A/D Conversion
area. These adjust the indicated flow rate to match the actual flow rate. Since this is a userprovided transducer, there is no automatic calibration function for this input. The Max Scale
should correspond to the stack flow producing the maximum analog input current (20 or 24
mA), while the Min Scale should correspond to the flow producing the minimum analog input
of 0 or 4 mA. The user will be required to create a manual procedure which provides a 2
point calibration process, and adjust the Min Scale and Max Scale values until the desired
readings are achieved.
The Alpha-7 also allows the use of an fixed flow rate for facilities that do not have an in-line
flow sensor installed. This is selected using the edit field and check box in the Flow Simulation
area in the lower left hand corner of the display.
Use Fixed Flow— is a checkbox to enable the use of fixed Stack Flow.
Flow Rate— defines the Stack Flow rate to be used— in the currently selected units.
Analog Output Properties
The Analog Output tab controls the operation of the 4 to 20mA analog signal that is generated
by the Alpha-7. This signal is proportional to the magnitude of the analog output value. The
analog output value is determined as follows:
??
If a Flow Rate (Sample or Release) is selected to appear on Page 1 of the Alpha-7
display, the analog output value will be the current displayed flow rate.
??
If an isotope or region is selected to be displayed on Page 1, the analog output value will
be the Fast or Slow reading for that isotope or region, depending on a factory-defined
output setting. The Fast reading is the default and updates once per second. If the Slow
reading is configured to drive the analog output, then remember that the slow readings
are calculated only once per minute, so the analog output value will only change once per
minute.
The analog output is a logarithmic signal3, and units of the output are identical to those
selected for the display.
Jumper settings on the Display Board define the range of the analog output and can be set for
0-20 mA, 4-20mA or 4-24mA. The default jumper setting is for 4-20mA output.
Min Scale— is the maximum value which will produce the 4mA minimum output current. Any
values less than Min Scale will also cause the 4mA signal to be output.
Decades— is an integer value which defines the number of logarithmic decades spanned by
the analog output. Once a minimum value and the number of decades is specified, the
maximum value, which corresponds to a 20mA output signal, is calculated based on these
two operator inputs.
3
A linear analog output is also a factory-settable option.
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MCA Properties
The MCA page is used to examine the gain and threshold settings as well as the detector bias
voltage. In the Alpha-7 Calibration Wizard, the edit boxes can be used to enter the values or
the slide switches can be moved using the mouse. Once the instrument is calibrated (using
the Alpha-7 Calibration Wizard software supplied), these settings should not be changed
because any changes may invalidate the calibration.
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The settings shown are typical values. Small changes to Bias and Threshold have relatively
little effect, but the Gain setting is critical. Any gain change will shift an entire spectrum. This
in turn may lead to an OUT OF CALIBRATION status and/or poor performance resulting from
less than optimum curve fitting of the spectrum. The 4-Pi Efficiency is the intrinsic detector
efficiency for the calibration isotope used. This efficiency is dependent upon detector to filter
spacing, air density and source geometry. The recommended calibration source is a single
alpha-particle emitter in the 5 MeV energy range plated onto a stainless steel disk with a 1
inch (25 mm) active area. 239Pu is the typical calibration isotope used, and is the isotope used
in factory calibration.
NOTE: These values may only be edited using the Alpha-7 Calibration Wizard.
For a detailed description of calibration, please refer to the Alpha-7 Calibration section.
Versions Properties
The Versions properties are used to display the software versions used in the Alpha-7. This
can be used to quickly determine which software versions are resident. Both the MCA and
Display Boards use EPROMS and cannot be updated without a hardware upgrade. The
A7Server is resident on the hard drive. The properties for Versions is shown below. The
Alpha-7 Client version is not shown in this page since it is not an integral part of the Alpha-7
instrument operation.
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Alpha-7 Isotope Parameters
Each isotope entered into the isotope tree for a specific Alpha-7 has its own parameter page
that configures the operation of the Alpha-7 for that isotope. To change the parameters for
any isotope in the Alpha-7 isotope tree, right-click on the Isotope icon that you would like to
modify and select Properties… from the Isotope Menu.
This dialog box shows the isotope being edited in a window in the upper left corner of the
dialog and provides information on the individual isotope parameters.
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Exercise caution in editing these parameters. In particular, please be very careful about the
alarm levels and about changing the units of the measurement. Changing the units should be
done only during calibration to ensure that the correct values and conversion factors are used.
The tabs are:
General
Fast Alarms
Slow Alarms
Simulation
General Isotope Properties
The Energy Parameters (MeV) window lists several non-editable isotope parameters. The
Reference Energy defines the actual isotope decay energy as derived from the
Isotopes.mdb database. Current Peak is the energy corresponding to the peak channel in
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the spectrum. On a properly calibrated CAM, the difference between these two energies
represents the attenuation across the air gap between the filter paper and the detector and is
the Peak Offset.
The Calibration parameters consist of the Activity Units, the DPS/Units conversion factor and
the DAC Unity constant.
Activity Units— is the text-based units used for isotope activity. The Alpha-7 is an extremely
flexible instrument allowing the use of text-based units of measurement. The user may enter
any desired units for the Activity units, and then simply enter the conversion factor from DPS
to the Activity Units in the DPS/Units field. Units of µCi are created by default, but units of pCi
are being used in the example above. If units of Bq are used, conversion between DPS and
Bq simply uses a conversion factor of 1.0, since one Becquerel is one disintegration-persecond.
DPS/Units— is a conversion factor expressed as disintegrations-per-second per each unit of
activity. For example, the display above shows an efficiency of 0.037 DPS/Unit. Since the
Activity Units are pCi, this translates to 0.037 DPS/ pCi. This factor should only include the
conversion for units. The detector efficiency conversion and allowance for the isotope decay
abundance is handled automatically.
DAC Unity— is the value for DAC expressed as a divisor of the activity in the selected Activity
-12
Units. For example, the DAC value for Pu-239 is 2 x 10 where the units are µCi/cc. The
concentration in air based on the Activity Units and the units selected for air flow is divided by
this value to calculate the DAC value. This value is used for alarm determination and local
display as well as being displayed in the Dose Control and logged (if desired). If the DAC
constant is 1.00, the concentration will be displayed using Activity Units. In this situation, the
alarm determination is also performed in the activity units rather than DAC or DAC-h. If DAC
and DAC-h are to be used for alarm determination, logging and display, this value should be
set to the conversion factor described above.
Logging— controls the archival of data from this isotope to the A7Log.mdb Microsoft Access
database. If the Archive readings to database box is checked, the data for this isotope will
be logged into the database at the interval specified in the every 1 minutes edit box. Data
may be logged at different intervals for each isotope.
Enable Alarm Settings— enables alarm level edit fields in the Fast Alarms and Slow Alarms
pages of the dialog.
Display Reading(s)— specifies whether to show the readings from this isotope on the front
panel display of the Alpha-7. You may display either Slow readings, Fast readings or both.
Page(s)— further defines how the display of isotope readings will be performed. If you choose
to display only the Slow or the Fast reading, you may then specify the display page for the
reading to appear on in the On Page(s) field. If both Slow and Fast readings are checked,
then the Alpha-7 can display both readings on one page, toggling the reading every five
seconds, or on separate pages. To display both readings on one page, choose Toggle Page
then specify the desired display page in the On Page(s) field. To display the readings on
separate pages, choose Separate Pages and specify the page for the Slow reading in the On
Page(s) field. The Fast reading will automatically be assigned to the next page.
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The Alpha-7 automatically manages the display pages to eliminate blank pages between
isotopes and to prevent the selection of the same page for more than one isotope. If there
are blank pages between the selected page and the last used page, the information will be
displayed on the next blank page. If a page is already in use, the information for the isotope
being edited will appear on the next available page. Since the Alpha-7 only displays the data
for active pages, this allows the user to scroll continuously through the pages without having
blank screens in the middle or the end of the scroll pattern. There is a maximum of 10 pages
of information available. The information displayed on any given page can be flow rate or the
concentrations of the isotopes. Page 0 is reserved for the name and operational status of the
Alpha-7.
Fast and Slow Alarms Properties
As described in the Theory of Operation section, there are two types of alarms in the Alpha-7:
Fast (or Acute) and Slow (or Chronic). The difference between the two is based on the time
window over which changes in count rate are observed.
When the Alpha-7 checks for alarms, the current values for the isotope are compared against
the slow and fast alarms levels selected by the user. If the current value exceeds an alarm
level or the MDC, whichever is higher, the alarm will be annunciated using both the audible
and visual indicators. Pressing the Alarm Ack. button on the front of the Alpha-7, or remotely
acknowledging the alarm from the Alpha-7 Client by right-clicking on the instrument and
selecting Acknowledge Alarm will silence the audible indicator. If Latching Alarms are
enabled at the factory, the visual indicator will remain on until the reading falls below the high
alarm set points. If not, the alarm acknowledge will clear the visual indicators and relay as
well.
Alpha-7L Specific: Since the Alpha-7L is configured with latching alarms, the beacons
and status will continue to show an alarm status until the condition causing the alarm
has ceased and the alarm has been acknowledged again at that point.
Corresponding to the two types of alarms are two parameter pages in the Isotope Properties
dialog. The pages are similar, but not identical. The differences will be noted below. Also,
depending on whether Alert Alarms are active or not (they are disabled on the Alpha-7L), the
Concen Alert settings will or will not appear.
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Window— defines the time window (Fast Window is in seconds; Slow Window is in minutes)
over which the net count rate for the isotope is determined— and similarly, the dose. The
difference in two successive net count rates is used to determine concentration. Since the
window time affects the calculation of concentration and dose, this value can be edited even
if the alarms are disabled.
As described in the legend, the window setting is the evaluation time over which the change in
count rate is evaluated to determine an increase or decrease in the rate of accumulation. For
the fast evaluation window, the limit is from 1 to 300 seconds, and for the slow evaluation
window, the limit is from 1 to 120 minutes. The use of this evaluation window will be more
fully described in the Theory of Operation section.
Concen Alarm— is the alarm level in the units specified. In the example, the units are DAC.
The FAST/SLOW CONCEN condition will be signaled when the measured Fast/Slow
Concentration exceeds this level, or the MDC, whichever is higher. Check the Disabled
checkbox to disable checking of this individual alarm.
Concen Alert— is the alert level in the units specified. The FAST/SLOW ALERT condition
will be signaled when the measured Fast/Slow Concentration exceeds this level, or the MDC,
whichever is higher. Check the Disabled checkbox to disable checking of this individual alert.
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Dose Alarm— is the dose level in the units specified. The FAST/SLOW DOSE condition will
be signaled when the measured Fast/Slow Dose exceeds this level, or the MDA, whichever is
higher. Check the Disabled checkbox to disable checking of this individual alarm.
Release Alarm— is used only on the Slow page of the dialog and is the release rate level in
the units specified. In the example, the units are pCi/min. The RELEASE RATE condition will
be signaled when the measured Slow Concentration times the stack flow rate exceeds this
level. The stack flow rate can be based on either a fixed flow rate (check box) or a 4 to 20 mA
analog input from a stack flow sensor. Check the Disabled checkbox to disable checking of
the Release Alarm.
Simulation Properties
A simulation mode is provided for each isotope. This mode can be used for demonstrations
and training exercises. This mode generates a spectrum peak for the selected isotope based
on the normal spectrum shape and the chosen simulated concentration. Counts grow into the
spectrum randomly just as they would in normal operation, and all alarm and measurement
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functions are applicable to the simulated counts just as they would be for the real counts from
the detector.
CAUTION: Since there is no way for the user to distinguish between simulated counts
and real counts without examining the simulation page, caution is advised when
using this mode. The simulated counts can generate alarms and activate the alarm
relay contacts.
Generate simulated counts for this isotope— activates the simulator for this isotope.
Simulated Concentration— is the concentration level, in the units specified, for which an
appropriate count rate will be generated. The simulator may continue to generate simulated
counts, even after the Simulated Concentration has been set back to zero. Simulated
deposits on the filter paper will continue to cause counts, long after the Simulated
Concentration is reset to zero. The only way to stop the simulation is by unchecking the
Generate simulated counts for this isotope box.
Simulate entire decay chain— causes simulated counts to be generated for all isotope tree
daughters of this isotope. Simulated concentration of a decay daughter will be based on the
Simulated Concentration of the parent and the parent’s half-life. To simulate counts only for
this isotope, uncheck the box.
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CAUTION: Simulating isotope concentrations consumes a significant amount of
processing time. Do not create simulations for more than two isotopes at any one
time.
Adding Isotopes
The Alpha-7 can be shipped configured with any list of isotopes. It is usually configured with
only three radon daughters: Po-218 (RaA), Po 214 (RaC’) and Po-212. These isotopes show
up in the list of isotopes under each instrument in the Tree Control.
The list of isotopes can be modified by right-clicking on the Alpha-7 instrument icon in the list
to bring up the Instrument Menu. Left clicking on New Isotope... brings up the Add Isotope
dialog box containing a list of available isotopes.
The list shown contains the isotopes defined in
the file Isotopes.mdb in the
C:\Eberline\Alpha7\Data folder of the shared
drive of the Alpha-7. This is a Microsoft Access
database, which can be easily modified to add or
delete isotopes from the library, or change the
definition of existing isotopes in the library. The
list itself can be can be restricted by checking the
two checkboxes.
List Parents Only— When this box is checked
the list of isotopes will show only those isotopes
whose “Parent”flag is set in the Isotopes.mdb
database. With List Parents Only checked, the
list of isotopes is shorter.
Add entire decay chain— When this box is checked, then when an isotope is added, all
decay products of that isotope are also added. With Add entire decay chain checked, adding
Rn-220 also adds the isotopes Po-216, Po-212, Bi-212, and Po-212.
To add an isotope, click on the desired isotope, and then click on OK. Alternately, just doubleclick on the isotope you want.
NOTE: Since additional computation overhead is created for each isotope listed in the
isotope tree, best performance will be achieved when only the isotopes which
generate alpha particulates are added to the tree.
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Adding a Region of Interest
In addition to the normal isotopes defined in the database, a special case entry may be
defined in the Isotopes.mdb database to represent regions of interest. A Region of Interest
entry is any isotope name in which the peak energy for that isotope is defined as 0 MeV. The
Region Name may be up to 8 characters long. This Region of Interest will then be available
from the list in the Add Isotope… dialog box described in the previous section. The example
dialog above lists the standard MixedU isotope which is the Region of Interest entry in the
supplied database.
In place of the normal Energy Parameters, the Region of Interest limits will be displayed.
These limits are user-definable.
Lower Bound— defines the lower end of the region in MeV.
Upper Bound— defines the upper end of the region in MeV.
Counts in the Region of Interest are defined to be the total counts in the region, minus any tail
counts from isotopes whose peak is outside the region, but whose tail extends into the region.
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The values selected are applicable only to the particular instance of the Region of Interest
displayed. If the user adds the same region from an equivalent isotope database to another
Alpha-7, the user can set different limits for that Alpha-7.
All other functions normally associated with an isotope will function with the Region of Interest
isotope definition with the following exception: There is no simulation available for a Region
of Interest. Region of Interest calculations are performed using a different method than
normal isotopes. While normal isotopes have a calculated curve fit which is used to
determine the total counts for that isotope, Region of Interest isotopes sum all the counts for
the channels between and including the defined boundaries, then subtract the counts that
intrude into the Region of Interest from all curve-fitted isotopes whose peak energies are
outside of the defined Region of Interest. This provides the normal gross count benefits
associated with a Region of Interest while providing the additional accuracy of the curve-fitting
algorithm for the subtraction of counts from other isotopes that may interfere with the desired
Region of Interest.
Removing Isotopes or Regions.
Only isotopes in the first level of the isotope tree may be deleted. The other isotopes that
typically represent daughter products of the parent in the first level cannot be deleted.
To remove an isotope that is not grayed out, just right-click on it in the list associated with the
desired Alpha-7. Select Delete... from the Isotope Menu. Daughter products in the second
level of the tree may only be deleted by deleting the parent, then adding the parent back
without the daughters.
CAUTION: The Alpha-7 is designed to accurately correct the measurement for the
influence of the radon daughters. For this reason, the alpha particulate radon
daughters must be included in the list of isotopes and in the list under the Alpha-7 in
the display. Radon daughters may be included as progeny of the naturally occurring
radon isotopes, or may be added individually without the parent isotopes to limit the
number of isotopes being maintained by the Alpha-7. This method is particularly
appropriate when some of the isotopes or daughters produce no particulates or
produce isotopes that have no alpha emissions. The method of adding individual
daughter products is the preferred configuration since it minimizes the complexity of
the tree and limits the total number of isotopes tracked by the Alpha-7.
CAUTION: Adding and deleting isotopes can immediately and directly affect the
quality of the curve fit of the current spectrum. It is highly recommended that isotopes
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only be added or deleted during the calibration process and not during normal
operation to insure that the instrument continued to function in a known, controlled
configuration.
Using Profiles To Create Standardized Configurations
Profile Overview
Setting up the many parameters of an Alpha-7 can be a complicated task. The effort is
multiplied when the CAM system contains many instruments and each instrument’s settings
must be identical, or if a single Alpha-7 is used for several monitoring tasks requiring different
settings that must be swapped frequently. To reduce this effort, the Alpha-7 server program
provides capability for configuration “profiles”to automatically configure the settings of an
instrument to a saved set of parameters. This means that for a large system, only a single
instrument need be set up manually, then the parameters for that unit can be saved in a
profile and used to “clone”all the other instruments by simply placing the profile file on the
hard disk of each instrument and re-starting the unit. An additional benefit of configuration
from a profile is that several different profiles can be created and kept ready to quickly
reconfigure an Alpha-7 for different types of applications (e.g. stack monitoring, room
monitoring, etc.).
NOTE: Instrument-specific and remote sampling head parameters are not included in
the profile so that when a new profile is installed, the instrument-specific parameters
(e.g. instrument name, calibration settings, etc.) are not changed.
Creating A Profile
CAUTION: Creating a profile requires a working knowledge of the Microsoft Windows
Registry Editor. Changes to the Windows Registry may render the Alpha-7 inoperable!
This step should be performed by an experienced Windows user.
To create a profile, first configure the Alpha-7 with the appropriate alarm settings, units,
display pages and any other parameters that you want to be saved in the profile. Once the
configuration is complete, the settings (saved in the Microsoft Windows registry) can be saved
to a profile file using the Microsoft Registry Editor. This can be done either remotely across a
network (from a Windows NT/200/XP computer), or locally if a keyboard, mouse and monitor
are attached to the Alpha-7.
If done remotely, a Remote Administration privilege is required. See your network
administrator to make sure the privilege is enabled.
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From the Start button, select Run… , type in
“regedt32”and press OK.
NOTE: If Windows cannot find the
program, you can Browse… to it in the
System (Win95/Win98) or the System32
(WinNT/Win2000/WinXP) subfolder under
the Windows folder.’
When the Registry Editor appears, the registry key
windows will be displayed. If you are creating the
profile locally, the appropriate screens will already
be displayed. If you are running RegEdt32
remotely across a network, select the Registry
menu then click on Select Computer… and type in
the name of the Alpha-7 you wish to create the
profile from. Select the HKEY_LOCAL_MACHINE
window and expand the
SOFTWARE/Eberline/Alpha-7/1.5/ key. You will
see the Profile key as a subkey under the 1.5 key.
Select it then pull down the Registry menu, select
Save Key… choose a destination folder where you
want to save the profile and give the profile a file
name (e.g. “standard_config”). The default
extension is “.reg”but you may add a different
extension if you wish.
Loading A Profile
Once a profile is created, to clone those settings to other instruments, start by making a copy
of the profile file and renaming it to “profile.reg”. This name is important, as the Alpha-7 will
only recognize a profile with this name.
Next, copy the profile.reg file to the C:\Eberline\Alpha-7\ subfolder on each instrument you
wish to reconfigure. When the file has been copied, restart the unit— either from the front
panel pushbutton, or remotely from the Alpha-7 Client using the Instrument Menu and
selecting Restart… .
When the Alpha-7 starts up, it looks in the current folder to see if the file profile.reg exists. If it
does, the program will read its contents, restore the settings in the registry, delete the file, then
start up normally.
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Setting Up the Alpha-7 Client Display
The Alpha-7 Client display is split into three sections. The Tree Control on the left shows the
list of Alpha-7's being monitored. The upper and lower portions of the right side of the display
can be any combination of two of the following types of display: Chart Control, Spectrum
Control, or Dose Control. Each control will reflect the data for the Alpha-7 currently selected
from the Tree Control on the left side of the display.
Spectrum Control
The Spectrum Control shows the Alpha-7 spectrum with an overlaid red curve fit for the
isotope selected. If no isotope is selected, the curve represents the sum of all the individual
isotope curves and fits the entire spectrum. The scale for the spectrum is auto-scaling.
Right-clicking anywhere in the spectrum display will present the user with the Spectrum
Popup Menu.
The user can select the auto-scaled Full Spectrum from the list, or
choose Zoom In and drag a box around the area of interest by
holding down the left mouse button and dragging the box corner to
the desired size. However, if a specific region of the spectrum is of
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greater interest, select Properties… . This will allow you to change the scale factors— in both
the x- and y-axis.
Reset Spectrum will zero all spectrum counts. This will clear all counts in the spectrum, but
since the accumulated activity is still on the filter paper, the integrated sample flow volume or
elapsed time since last filter change data will not be reset. Those data are only cleared when
a filter change is recognized.
The user may also save the current spectrum in a comma-delimited ASCII text file by
selecting Save Spectrum… . The user will be prompted to provide a path and a name for the
text file, which will then be saved in the specified location. Saved in the file in three columns
are the channel number, channel counts, and curve fit value.
Choose List Statistics to display curve fit statistics that provide a measure of the quality of
the curve fit as well as the total counts in the spectrum. The lower the value for the fit ratio,
the better the curve fit. Values below 1.0 are generally considered to be a good fit.
The Spectrum Control can provide additional information on the spectrum through the use of
tool tips. If the cursor icon is placed on the spectrum over an individual bar in the spectrum
display, a tool tip will appear as a legend with the current channel, the corresponding energy
for that channel, and the number of counts in that channel. This tool tip will remain as long as
the cursor is in place, and will update automatically as the spectrum is updated.
Spectrum Control Properties
The Spectrum Control properties dialog allows for additional customization of the spectrum
display.
Update interval (sec)— defines the frequency with which new spectrums are acquired for
display update.
List Statistics— provides the same function as selecting the feature from the popup menu.
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Auto-Scale— allows the Y-axis of the spectrum display to update automatically whenever the
peak counts in any channel exceed the max scale.
Min Scale and Max Scale— define fixed limits to the Y-axis when Auto-Scale is turned off
(unchecked).
Entire Spectrum— controls the display of the X-axis. When this box is checked, the entire
energy spectrum from 0 to 10 MeV is displayed. When unchecked, the max and minimum
energies bounding the X-axis are defined by the Max energy and Min energy values.
Checking both Auto-Scale and Entire Spectrum performs the same function as selecting Full
Spectrum from the popup menu.
Dose Control
The Dose Control lists individual isotope data in tabular form. The DAC (Derived Air
Concentration), DAC-h, concentration in activity per unit volume, net cps, and gross counts
for each isotope selected to appear in the Dose Control table.
The Dose Control can display either Fast or Slow values. Right-click on
the header section of the control (showing the integrated volume,
airflow, Alpha-7 location, etc.) and select either Fast Readings or Slow
Readings.
DAC values are only displayed in the Dose Control window if the DAC Unity value is set to a
value other than 1.0. Otherwise, the DAC and DAC-h columns will be blank for that particular
isotope.
Because a concentration or DAC reading is based on a difference in count rates, there is
usually a statistical mean of zero. This means that the DAC or concentration value, in the
absence of any meaningful isotope activity, is below zero about as often as it is above zero.
In cases when the values are below zero, the value displayed for the concentration will be
shown as “< 0.00”. The MDC displayed is the minimum statistically valid measurement that
can be made by the Alpha-7 under the current conditions for the isotope selected. This value
will be displayed in the same units as the concentration.
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Dose Control Properties
Dose Isotopes— can be added to or deleted from the Dose Control by right-clicking on the
header for the control (the area with the legend data) and selecting Properties… . A Dose
Control Properties dialog will be appear which will allow the user to add or delete isotopes
from the control. To add an isotope, type in the isotope name as it appears in the Tree
Control and press the Enter key. To delete an isotope, click on the isotope to select it and
press the Delete key.
Show Negative Values— is a checkbox which, when checked, configures the control to
display negative readings. The unchecked default is to display “< 0.00”whenever a reading is
below zero.
When modifications are finished, click on the OK button. Isotopes being added must already
have been added to the tree for that instrument. Any isotope that is in the Dose Control but
not in the isotope tree for the instrument selected will be shown in the table but will not display
any data.
Chart Control
The Chart Control shows the strip chart plot of concentration against time for the isotopes for
either Fast or Slow Readings. This Chart Control requests historical data from the
A7Log.mdb database stored in the Alpha-7, and then adds new data to the chart as it is
accumulated.
Right-clicking on the title block of the Chart Control will allow the
operator to select different resolutions of data. The minimum
resolution of the data is 1 minute for archived data based on the
Slow evaluation period. Increased resolutions are averages of the
next lower resolution for that time interval. Example, 10-minute data
is an average of the 10 1-minute intervals contained in that 10
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minute period. Resolutions of 1-minute, 10-minute, 1-hour and 1-day are provided in the
Alpha-7.
No history is provided for the Fast evaluation interval data, which is updated as it occurs at 5
second intervals when the Fast interval data is selected for the Chart Control.
If another display function is selected, the Chart Control will restart when next selected.
The horizontal axis of the strip chart reflects time, with the newest data displayed on the right
hand side of the chart. The vertical axis is represented as the percentage of the alarm setting
for each isotope selected to appear on the strip chart. The red line represents the high alarm
set point for the selected evaluation interval.
NOTE: If the Concen Alarm set point is below the MDC for an isotope displayed in the
strip chart, the isotope may exceed the red line without generating a high alarm.
Chart Control Properties
Chart Isotopes— are entered and deleted just like in the Dose Control properties dialog.
Type a new Isotope in the edit field and press Enter to add an isotope. Select an isotope from
the list and press Delete to delete an isotope from the chart.
Show Negative Axis— controls the display of a chart region below zero concentration. When
checked, a negative Y-axis is displayed.
When modifications are finished, click on the OK button. Isotopes being added must already
have been added to the tree for that instrument. Any isotope that is in the Chart Control but
not in the isotope tree for the instrument selected will be shown in the legend but will not
display any data.
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RadNet Configuration
RadNet is a non-proprietary data acquisition solution for radiation monitoring instruments that
allows various types of instruments from many different manufacturers to be placed in an
Ethernet network and viewed over the network using a single piece of software. The Alpha-7
is fully RadNet compliant supporting the transmission of both current readings and spectrum
data across a network.
The RadNetSvr.exe Utility
RadNetSvr.exe is a utility program located in the C:\Eberline\Alpha7\ folder that provides the
RadNet support in the Alpha-7. It is executed on startup by the Startup.bat file. To minimize
overhead on the computer, if no RadNet support is required, the RadNetSvr startup
command in the Startup.bat file can be commented out as follows:
REM start radnetsvr
Using the RadNet Server Properties Dialog
The RadNet system is configured using the RadNet Server Properties dialog. From the
Instrument tree in the Tree Control, right-click on the appropriate instrument and select
RadNet Config… to call up the dialog shown.
NOTE: The program RadNetSvr.exe must be started and running before the RadNet
Config… menu is available.
Server Properties
Server Address— is defined on the Server page of the RadNet setup pages. Multiple
Alpha-7s can be assigned to the same Server Address allowing them to be grouped together
by location or function. Both the Server Address and the Alpha CAM Address (on the Alpha
CAM page) range from 1 to 255, allowing in excess of 64,000 possible combinations.
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Allow Negative Values— is a setting which allows transmission of negative concentration or
dose readings. The default is Off, meaning if any of the data is negative, a zero will be
transmitted for that value.
UDP Port— applies to the port number of the UDP transmission and cannot be edited at this
time.
Alpha CAM Properties
The Alpha CAM page is for settings that apply to the particular Alpha-7.
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Alpha CAM Address— is the second part of a two part address consisting of the Server
Address and the Alpha CAM Address. The range is 1 to 255 and each CAM must have a
unique two-part address.
Enable Broadcasts— controls whether the RadNetSvr software will transmit data for this
instrument. The two types of broadcasts are Measurement data and Spectrum data. The
Server can transmit either or both packet types. The selected data will be broadcast for all
isotopes that are listed in the Rnisotope.txt file, as described in the RadNet Files section
below.
Measurement— is the checkbox which enables periodic transmission of RadNet
measurement packets.
Spectrum— is the checkbox which enables periodic transmission of RadNet spectrum
packets.
The Broadcast interval settings are to allow different broadcast frequencies for Normal
operation and Abnormal conditions. Typically the instrument is expected to send data more
frequently whenever there is an abnormal condition. The time intervals are set in seconds
with a range of 1 to 6000.
IP Addresses Properties
The IP Addresses page lists the addresses and subnets to which the RadNet data will be
broadcast. This data is saved in the Rnlist.txt file in the C:\Eberline\Alpha7\ folder.
Broadcast IP Addresses— RadNet requires this list contain at least one entry to which the
data should be transmitted. The IP address can also be a subnet broadcast address. For
example, if you specify address 128.1.0.23 to reach a specific PC, you could specify
128.1.0.255 and reach all of the PC’s on that subnet.
To enter an IP address, type the address in the edit field and click the Add button. The new
address will appear in the list.
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To Edit an IP address, click the address in the list and click the Edit button. Edit the values in
the edit box. Click the Add button when you are finished editing.
To remove an address, click the address in the list, then click the Remove button.
RadNet Files
There are two text files in the C:\Eberline\Alpha7\ folder that are used for RadNet support.
One is the RnList.txt file. This file specifies the IP addresses that the Alpha-7 will broadcast
all RadNet messages to. If an IP address is not in this list, the computer with that IP address
will not receive any RadNet data. While it is possible to edit this file manually, it is
recommended that the user set the broadcast addresses through the RadNet Server
Properties dialog discussed in the RadNet Configuration section.
Example:
10.1.4.99
10.3.8.4
The last entry is followed by a carriage return. Broadcasts may be made to a subnet by using
“0”as the entry for all monitors on that subnet, such as 10.3.8.0.
The other text file used is RnIsotopes.txt. This file contains a list of isotopes and the
conversion constants for each isotope. This list represents the isotopes for which data will be
broadcast on RadNet. The conversion constant is the number that the current reading for a
given isotope must be multiplied by for the result to be transmitted in the standard RadNet
Units of Becquerels/cubic centimeter (Bq/cc). This conversion constant converts the
concentration reading from its current form to Bq/cc. The isotope and the constant are
separated by a tab or space. The example below assumes that the concentration for both
isotopes on the Alpha-7 is being displayed in µCi/cc.
Example:
Pu-239 3.70E+010
Po-218 3.70E+010
NOTE: This file MUST be edited manually using a text editor such as Windows
Notepad. After editing this file, the Alpha-7 must be restarted for the changes to take
effect.
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Database Data Source Configuration
The two Microsoft Access databases used by the Alpha-7, A7Log.mdb and Isotopes.mdb
reside in the Data\ folder and the Data\History\ folder respectively, of the Alpha-7 hard drive.
It may be desirable, in some situations, to place the database files on a network file server,
instead of on the local instrument.
Since the programs used in the Alpha-7 do not directly access the databases, but instead, rely
on a protocol called Open Database Connectivity— or ODBC, for short— a simple redefinition
of an ODBC setting can redirect the path to the files. This section describes the procedure for
defining the ODBC Data Source to point to a network drive.
Setting Up The File Server
Before changing the Data Source definitions, the new database file(s) must be saved on the
file server which the Alpha-7 will reference. Create a folder and copy A7Log.mdb from the
Empty Database\ folder and/or Isotopes.mdb from the Data\ folder to the new folder(s) on the
file server.
Running the ODBC Data Source Administrator
The change of the ODBC Data Sources must be done from the Alpha-7 using an attached
keyboard, monitor and mouse. (Connection of a mouse usually requires restarting the
Alpha-7.)
From the Start menu, select Settings the Control Panel. Double click on Data Sources
(ODBC) to run the ODBC Data Source Administrator.
Changing The Data Source
The Alpha-7 Data Sources are listed under the System DSN tab.
Click on either the Alpha-7 Data or the Isotopes Data Source and click the Configure…
button. In the dialog that pops up, Click Select… , create the Map Drive path to the appropriate
file server file, then click OK.
The Data Source is now set to access the file server database. Change the other Data
Source, if necessary, and restart the Alpha-7 for the changes to take effect.
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Filter Paper Considerations
With both the In-Line Head and the Radial Entry Head, the recommended filter paper for use
with the Alpha-7 is a 47-mm diameter Millipore Fluoropore Teflon-membrane filter with a 5
µm pore size.
Particle collection tests performed at the Lovelace Respiratory Research Institute in
Albuquerque, NM have shown essentially 100% collection efficiency for 10 µm diameter
particles with a flow rate of 1 CFM.
The design also permits the substitution of 2-inch filters. The Fluoropore filter has a smooth
Teflon membrane collection side (which prevents the spectrum-broadening associated with
deep burial of deposits in a porous paper providing a high-resolution Alpha energy spectrum)
and a fibrous support side, which improves pressure-drop characteristics. Install the filter with
the white Teflon side UP.
NOTE: Improper Fluoropore filter installation will result in a relatively poor spectrum if
the filter is installed with the support side facing the detector. For easy recognition,
the support side of the filter is a dark gray color.
Attaching A Vacuum Source
The operating sample flow range of the Alpha-7 is 0.5 CFM to 2.0 CFM (14 lpm to 57 lpm).
Recommended flow rate is1.5 cubic feet per minute (or 42 lpm). The flow source can be
either a vacuum pump or house vacuum system.
Radial Entry Sampling Head Connection
The Alpha-7 radial inlet sampling head, which is primarily intended to sample ambient room
air is fitted with a 3/8 inch NPT male pipe connection for vacuum supply.
In-Line Sampling Head Connections
The in-line sampling head is available with a 1 inch I.D. pipe inlet with light baffle cap. An
optional 1-inch I. D., 1 ¼ inch O. D. adapter is available for compression fitting connection to
standard 1 ¼ inch O. D. stainless steel tubing
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Routine Operation and
Maintenance
Status Conditions
The Alpha-7 has an extensive list of possible status conditions. These statuses may be both
isotope-level statuses and/or instrument-level statuses. The instrument-level status is present
at all times on Page 0 of the Alpha-7 display, and as a Tool Tip on the Tree Control under the
Alpha-7 Client whenever the cursor passes over the instrument icon in the tree. Isotope-level
statuses are indicated on the isotope display page, or from Tool Tips when the cursor passes
over an isotope icon in the Alpha-7 Client Tree Control.
The following tables list the annunciator behavior for the different status types possible on an
Alpha-7, as well as the list of all possible statuses and how they are typed. Because the
behavior is different for an Alpha-7L than it is for an Alpha-7A, please familiarize yourself with
the status list for your appropriate version of Alpha-7.
Status Descriptions
Normal
Unit is operating normally with no alarm, failure or maintenance
conditions.
Below Fast MDC
The minimum detectible concentration is above the fast alarm set point.
Below Slow MDC
The minimum detectible concentration is above the slow alarm set point.
Below Fast MDA
The minimum detectible activity is above the fast dose set point.
Below Slow MDA
The minimum detectible activity is above the slow dose set point.
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Filter Change
A filter change was sensed because the filter door was opened.
Isotope Change
An isotope was added or deleted from the isotope list by an operator.
Filter Dirty
Sensitivity has decreased because of dust loading or radon background.
The alarm set point is again below the MDC for at least one isotope.
Door Open
The filter door switch has sensed the door opening.
Calibrate
Unit is being calibrated.
Check Source
Check Source Mode has been commanded on the unit.
Low Flow
The Sample or Release flow is below the Low Limit.
High Flow
The Sample or Release flow is above the High Limit.
Slow Alert
The Slow Alert Limit has been exceed on at least one isotope.
Fast Alert
The Fast Alert Limit has been exceed on at least one isotope.
Slow Alarm
The Slow High Alarm Limit has been exceed on at least one isotope.
Fast Alarm
The Fast High Alarm Limit has been exceed on at least one isotope.
Slow Dose
The Slow Dose Limit has been exceed on at least one isotope.
Fast Dose
The Fast Dose Limit has been exceed on at least one isotope.
Release Alarm
The Slow Release Alarm Limit has been exceed on at least one isotope.
Calib Due
The calibration expiration date is in less than seven days.
Out of Calib
The calibration on this unit has expired.
Flow Fail
The Sample or Release flow is below the Fail Limit.
Poor Curve Fit
The defined isotopes cannot be fit to the given spectrum.
Display Comm
Communications with the Alpha-7 Display Board have failed.
MCA Fail
Communications with the Alpha-7 MCA Board have failed, or the remote
head has been disconnected.
Door Timeout
The filter door has been left open for more than five minutes.
Low Counts
No counts have been received from the detector in 10 minutes4.
MCA EEPROM
The stored SmartHead parameters failed the CRC error check.
Off Line
Unit is initializing.
Alpha-7A Status Annunciations
Annunciator
4
Instrument Status Condition
If the instrument is configured for “Filtered Air,”this timeout period is 3 hours.
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Normal LED
Alert Alarm LED
High Alarm
LED
Alarm Beacon
Sonalert
NORMAL
ON
3
BLINK
OFF
OFF
ALERT ALARM
ON
HIGH ALARM
ON
MAINT.
OFF
FAILED
OFF
ON
OFF
OFF
ON
OFF
OFF
OFF
OFF
OFF
OFF
OFF
ON
OFF if Acked
ON
ON
OFF if Acked
OFF
OFF
OFF
OFF
Alpha-7A Status Conditions
STATUS
Normal
Below Fast MDC
Below Slow MDC
Below Fast MDA
Below Slow MDA
Filter Change
Isotope Change
Filter Dirty
Door Open
Calibrate
Check Source
Low Flow
High Flow
Slow Alert
Fast Alert
CONDITION
NORMAL
NORMAL
NORMAL
NORMAL
NORMAL
NORMAL
NORMAL
NORMAL
MAINTAINANCE
MAINTAINANCE
MAINTAINANCE
ALARMED
ALARMED
ALARMED
ALARMED
STATUS
Slow Alarm
Fast Alarm
Slow Dose
Fast Dose
Release Alarm
Calib Due
Out of Calib
Flow Fail
Poor Curve Fit
Display Comm
MCA Fail
Door Timeout
Low Counts
MCA EEPROM
Off Line
CONDITION
ALARMED
ALARMED
ALARMED
ALARMED
ALARMED
FAILED
FAILED
FAILED
FAILED
FAILED
FAILED
FAILED
FAILED
FAILED
FAILED
Alpha-7L Status Annunciations
Annunciator
Normal LED
Trouble LED
Hot Job LED
Alarm Beacon
Instrument Status Condition
NORMAL
ALARMED
ON
ON
5
BLINK
OFF
OFF
6
4
OFF/ON
OFF/ON
OFF
ON
MAINTAINANCE
OFF
TROUBLE
OFF
FAILED
BLINK
OFF
OFF
OFF
ON
4
OFF/ON
OFF
BLINK
BLINK
OFF
5
Normal LED blinks when any concentration/dose alarm setting is below the MDC/MDA
6
LED is ON if Alpha-7 is configured as a Hot Job CAM (i.e. dose alarms disabled), OFF otherwise.
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Sonalert
OFF
ON
OFF if Acked
OFF
OFF
OFF
Alpha-7L Status Conditions
STATUS
Normal
Below Fast MDC
Below Slow MDC
Below Fast MDA
Below Slow MDA
Filter Change
Isotope Change
Door Open
Calibrate
Check Source
Filter Dirty
Calib Due
Low Flow
High Flow
CONDITION
NORMAL
NORMAL
NORMAL
NORMAL
NORMAL
NORMAL
NORMAL
MAINTAINANCE
MAINTAINANCE
MAINTAINANCE
TROUBLE
TROUBLE
TROUBLE
TROUBLE
STATUS
Slow Alarm
Fast Alarm
Slow Dose
Fast Dose
Release Alarm
Out of Calib
Flow Fail
Poor Curve Fit
Display Fail
MCA Fail
Door Timeout
Low Counts
MCA EEPROM
Off Line
CONDITION
ALARMED
ALARMED
ALARMED
ALARMED
ALARMED
FAILED
FAILED
FAILED
FAILED
FAILED
FAILED
FAILED
FAILED
FAILED
Alarms
When a radiological alarm is determined, the Alpha-7 will annunciate the alarm in several
ways: by turning on the red alarm beacon, the audible Sonalert, the red alarm LED on the
front panel (Alpha-7A only), and by energizing the alarm relay contact.
Whether the alarm annunciations are automatically cleared when
the condition is cleared depends on whether the instrument is
configured for “latching alarms.” If the instrument is configured for
latching alarms (Alpha-7L uses latching alarms), the alarm
indications will remain, until the operator acknowledges the
condition, even if the condition which caused the alarm no longer
exists.
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The audible Sonalert can be silenced with the Alarm Ack button on the front of the Alpha-7.
Alternately, right-clicking on the instrument in the Tree Control in the Alpha-7 Client brings up
the Instrument Menu at left, in which a left click on Acknowledge Alarm performs the same
function. Acknowledging the alarm only silences the Sonalert audible warning. The alarm
beacon will continue flashing until the Alpha-7 no longer measures a value that exceeds the
alarm set point for any isotopes.
Alarm Logging
In addition to the visual and audible indications, the EberLogger utility creates a log of the
alarm condition, and 30 minutes after the event, will archive a table of the spectrums for six
hours leading up to the alarm, and thirty minutes after. For details, see the Data Logging
section.
Filter Changes
The Alpha-7 uses standard 47 mm filter media. The two types of sampling head assemblies
require different procedures for changing the filter paper, however, in both cases, the filter is
placed on the filter support, which consists of a stainless steel micro-perforated screen. Next
a retaining apparatus is placed over the filter to hold the filter in position and to create
pressure against the O-ring, which prevents flow leakage around the edges of the paper.
Filter papers should be changed according to the filter type, dust-loading conditions, radon
background, alarm settings and required sensitivity. Testing has indicated that, under
“normal”conditions, the filters should be replaced at least once per week. In this case,
“normal”conditions consists of the recommended filter, a flow rate of 1CFM (28.3 lpm),
moderate radon levels (approx 0.5 pCi/l) and moderate dust levels. In a filtered-air
environment, it is possible that filter papers may be changed less frequently than once per
week.
To prevent any light induced counts, an internal switch is present in both head types which
turns off the detector bias voltage when the user starts to open the detector door. When the
filter door is opened, the instrument detects this condition with the switch and begins a “filter
change timeout.” If the filter door is re-closed in less than 10 seconds7, the operator is
prompted to press the acknowledge button to confirm a filter change. If the acknowledge
button is not pressed, operation resumes from where it was interrupted.
7
The default filter change timeout is ten seconds. This timeout can be changed by Eberline field service personnel, or at the
factory to provide for a longer interval for filter inspection without forcing a spectrum reset.
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If the filter door is closed after remaining open for more than 10 seconds, the Alpha-7 resets
the spectrum and the integrated volume, and restores the detector bias voltage.
If the filter change requires less than the filter timeout, make sure to acknowledge the filter
change by pressing the Alarm Ack. button when prompted with the message:
Was filter changed?
If Yes, press Ack.
After the filter change, verify that the Alpha-7 display briefly shows the FILTER CHANGE
status message to confirm that the procedure was completed successfully. If the display
continues to indicate the DOOR OPEN message, check for complete closure of the door or
cartridge lock. Failure to recognize the closure probably indicates that the retaining knob was
not fully tightened.
CAUTION: When using the recommended Fluoropore filter papers, be sure to make
sure new filters are installed properly with the black fiber backing face down.
Radial Entry Sampling Head
In the radial entry sampling head, the filter holder is attached to the radial head via a hinge
pin, and is secured at the top by a retaining screw. In the field, the technician unscrews the
retaining screw using the attached knob, and folds down the filter holder assembly. This
process exposes the detector face and provides access to the detector surface for cleaning
when necessary.
To replace the filter paper, unscrew the door latch, open the door and remove the filter
retaining ring. Remove the old filter paper, center the new paper on the pedestal and place
the retaining ring back onto the filter assembly, pressing firmly so that the O-ring seals
properly against the back of the filter paper.
Examine the detector face for dust or deposits and clean if necessary.
Close the filter holder assembly and screw the knob down finger tight. Observe the Alpha-7
display to verify that the FILTER CHANGE message is displayed.
In-Line Sampling Head
The in-line sampling head uses a sample filter cartridge for very efficient filter change
operations. This method allows the maintenance personnel to carry pre-loaded filter
cartridges and swap the old cartridge for the new one in a matter of a few seconds.
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To replace the filter, release the cartridge locking knob and remove the filter cartridge. Lift the
stainless steel lid and remove the old filter paper. Place the new filter paper over the double
O-ring seal and carefully lower the cover to hold the filter paper in place.
Return the cartridge and close the locking mechanism, observing the Alpha-7 display to verify
that the FILTER CHANGE message is displayed. If the filter was replaced in under 10
seconds, the display will prompt the operator top press the Alarm Ack. button to confirm that a
filter change occurred.
Alpha-7 Local Display
Display Pages
The Alpha-7 local display supports up to ten pages of information on its two-line vacuumfluorescent panel. Isotope and flow readings may be displayed on Pages 1 through 9 as
defined by the customer (see Alpha-7 Isotope Properties: Display Page). Page 0 is reserved
for the display of the Instrument Name, Instrument Status and the amount of accumulation
time on the filter paper in hours and minutes.
Since the data for the isotope displayed on Page 1 is output to the analog output, the primary
measurement isotope is defined to display on Page 1. Sample flow is usually placed on a
subsequent page, since it is often useful to know what the flow rate is.
It is not required that all ten display pages have isotope of flow data assigned to them. In fact,
limiting the pages displayed will improve the performance of the Alpha-7. An example of a
four-page display scheme with Page 1 the active page is shown below:
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Page 0
A7000109
NORMAL
118:43
Page 1
Pu-239: NORMAL
1.63 DAC-h
Page 2
Pu-239: NORMAL
17.2 DAC-h Fast
Page 3
Sample: NORMAL
28.3 liters/min
The Alpha-7 automatically manages the display pages to eliminate blank pages between
isotopes and to prevent the selection of the same page for more than one isotope.
Scrolling
The user can scroll through the display pages by pushing the Alarm Ack. button. When the
last page is reached, pressing the button once more will cause Page 0 to be displayed again.
Display Timeout Feature
If no scrolling is done for a specified timeout period (the factory default is two minutes), the
display will automatically return to either Page 0 or Page 1 depending on the instrument
status. For all normal instrument statuses (see Status Conditions section), the display will
automatically return to Page 1 after the timeout period. However, if the unit is in a failed
status, the display will return to Page 0, showing the failed instrument status.
Response Check And Challenge Test
Check Source Mode (Alpha-7A Only)
The user first inserts the check source into the source holder and inserts the source holder
into the Alpha-7 in place of the filter paper holder. The vacuum may be enabled or disabled
according to user preference, since the vacuum buildup will be on the backside of the source
and will not affect the detector. The check source mode is then entered by holding down the
Alarm Ack. button until the “CHECK SOURCE”reading appears (approximately seven
seconds). Once the check source mode is entered, the Alarm Ack. button should be released
since after approximately 10 seconds it will cause the instrument to shut down.
When check source mode is entered, the gross counts for the entire spectrum will be
displayed as a weighted average count rate in counts per second. The user then waits for the
count rate to stabilize, and can record the count rate at that time.
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Opening the filter holder lock— as is done when removing the source holder from the
Alpha-7— will force the Alpha-7 to exit the check source mode. The filter holder can then be
reinserted to start a new measurement.
Response Check and Challenge Test Mode (Alpha-7L Only)
The Alpha-7L supports an enhanced source check mode which tests several functions in
addition to a source count rate test.
The Response Test:
??
Displays the Sampling Head Part Number
??
Displays the Calibration Due Date
??
Compares the current configuration against a set of saved settings, flagging any
discrepancies
The Challenge Test:
??
Prompts for the operator to insert the check source
??
Checks for a source-caused alarm
??
Checks for the source dose to be within the acceptable range
??
Posts the test results
??
Prompts the operator to remove the source
??
Returns to normal operation
To begin the Response Test, press and hold the Alarm Ack. button until the RESPONSE
TEST MODE message is displayed. Release the Ack. button, then when the message “Press
Ack. To cont.”is displayed, press the Ack. button again momentarily to begin the test.
During the test, the Alarm Ack. button will advance to the next step, or confirm prompts or
questions.
The Challenge Test source isotope and acceptance range is defined in the Windows Registry.
The default isotope is Pu-239 and any dose in the range 1 – 90,000 DAC-h will pass the range
test. To change the defaults, edit the following registry values in the
HKEY_LOCAL_MACHINE\SOFTWARE\Eberline\Alpha-7\1.5\Profile\ key:
Source— is the name of the source isotope.
Source High DAC-h— is the upper limit of acceptable dose reading.
Source Low DAC-h— is the upper limit of acceptable dose reading.
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After the test is completed, a record will be created in the Response Test Log.mdb database
(in the C:\Eberline\Alpha7\Data folder) documenting the results of the test. As with the other
database files, this table can be viewed using Microsoft Access.
Power Down (Turning the Alpha-7 Off)
The Alpha-7 is a Windows NT based computer system. It requires the same care in shutting
down as any Windows-based computer. The power down operation can be performed
locally, from the front panel of the Alpha-7, or remotely, using the Alpha-7 Client program.
Remote Power Down
To turn the instrument off from a remote PC running the Alpha-7
Client, right-click on the instrument in the Tree Control of the
Alpha-7 Client. This will bring up the Instrument Menu shown at
left. Select either Power Down... or Restart...
These two messages have the same meanings as with the
standard Windows Shutdown… command. A message will appear
on the Alpha-7 display indicating when it is safe to turn the
instrument off using the power switch on the left side of the
Alpha-7.
If you are running the Alpha-7 Client program locally using a
monitor and keyboard, an additional Shutdown… menu item will
be listed at the bottom of the menu. Shutdown will stop only the A7Server program allowing
you update the software or perform database management without conflict with the A7Server
program.
Local Power Down
You can also turn off the machine locally by pushing and holding the Alarm Ack. button on the
front panel for approximately 15 seconds. The message “Local shut down? If Yes, press
Ack.”will appear. When the message appears, release the Ack. button and the press it again
momentarily to complete the shutdown sequence.
When the unit is ready to be powered down, a message saying it is safe to turn the instrument
off will appear.
NOTE: Either the CHECK SOURCE MODE or RESPONSE TEST MODE message will be
appear after holding the Alarm Ack. button down for 8 seconds. Continue holding the
button for an additional five seconds until the “Local shut down?” message appears.
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Alpha-7 Calibration
Calibration of the Alpha-7 is accomplished by use of the Alpha-7 Calibration Wizard
program8, A7Calib.exe. The Alpha-7 Calibration Wizard may be run from any network
computer that has the Alpha-7 Client installed. Since the calibration does require the
changing of sources and flow rates, it is recommended that the client computer be located
within easy access of the Alpha-7 being calibrated.
While the Alpha-7 Client program provides the means to change the isotope and alarm
configuration of an Alpha-7, it does not allow calibration information to be changed. The
Calibration Wizard provides the method for setting the amplifier threshold and bias voltage,
and for calibrating the MCA gain and energy offset, the detector efficiency, and the sample
flow min/max scale values. In addition, after connection to an Alpha-7 is established, the
Calibration Wizard contains a full-functionality Tree Control that provides all the setup and
configuration screens for the instrument operation without any of the parameters being
“grayed out”. This makes the calibration program extremely powerful and therefore its use
should be controlled administratively to limit unauthorized changes to Alpha-7s which could
affect the confidence in the measurement.
The calibration process consists of a series of steps that determine the amplifier gain, detector
efficiency, and min/max scale values to produce accurate sample flow readings. The steps
are normally used in series, but individual steps may be skipped if the user desires. The
program allows the instrument to automatically determine and select the correct gain and then
calculate the efficiency for a known source. This section is intended to provide you with a
quick reference to the calibration process and calibration screens.
8
Alpha-7L Specific: This program is not installed when the Alpha-7 client program is installed on a client computer, but can
be released on a controlled basis.
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Smart Head Technology
The Alpha-7 incorporates Smart Head technology, which means that calibration parameters
are saved, not in the Alpha-7 display unit itself, but in the remote sampling head. This
powerful capability means that a calibrated remote head can be connected to any Alpha-7
display unit and put into immediate service. All calibration parameters, including gain and
efficiency information, the head serial number, a property ID, and the next calibration due
date, are downloaded to the sampling head at the end of the calibration. This means that the
calibration of several remote heads can be performed in the shop using a single Alpha-7
display unit and hot-swapping the sampling heads when the procedure is completed.
Calibration can be performed on the sampling head only. There is no need to bring the entire
Alpha-7 into the shop to do a calibration.
Smart Head Parameters
The following table lists the calibration parameters saved in the sampling head after
calibration:
Parameter
Description
Value is
Bias Flag
Set at factory
Gain
True = positive bias detector
False = negative bias detector
Amplifier gain value
Alpha Threshold
Amplifier upper threshold value
User editable
Beta Threshold
Amplifier lower threshold value (unused)
Bias Voltage
Detector bias voltage
User editable
Efficiency
Detector 4-Pi efficiency
Calculated
Offset MeV
Energy offset in MeV
Calculated
Air Gap
Detector to filter air gap
Set at factory
Flow Max Scale
Sample flow max scale
Calculated
Flow Min Scale
Sample flow min scale
Calculated
Cal Date
Date and time of last calibration
Calculated
Cal Due
Date and time of calibration expiration
User editable
Serial No.
Eberline-assigned remote sampling head serial
number
Set at factory
Property ID
Customer-assigned property ID
User editable
Source
Description
Description of calibration source used
User defined
Source Activity
Calibration source activity
User defined
Technician
Name of technician performing calibration
User defined
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Hot-Swap Capability
The Alpha-7 supports hot-swapping of sampling heads. This means that the sampling head
can be disconnected from a running Alpha-7 and the same head, or a different sampling
head, reconnected at a later time. The Alpha-7 will sense when the head has been
disconnected and post an MCA COMM status (MCA communications failure) message.
When a head is reconnected, the Alpha-7 will determine whether the head is Smart Headcompliant, and if so, download the new parameters from the head— continuing operation with
a new (reset) spectrum. Of course, the head can also be disconnected and reconnected with
the Alpha-7 powered down.
Parameter Error Checking
To insure data integrity, the Smart Head parameters are error-checked when they are stored
and read back from the sampling head using a CRC-32 check word.
In the event that an error is detected, the Alpha-7 will post a MCA EEPROM status. The
customer should then attempt to recalibrate the head to clear the condition. If the condition
does not clear after re-calibrating, then the sampling head should be returned to the factory
for repair.
Running the Alpha-7 Calibration Wizard
In the C:\Eberline\Alpha7 folder on the Alpha-7 (or the C:\Program File\Eberline\Alpha7\ folder
on the PC you are using to calibrate the Alpha-7) you will find the Alpha-7 Calibration Wizard
file A7Calib.exe. A screen capture of the folder is shown below. Please note that the Alpha-7
Client program and the Alpha-7 Calibration Wizard software use similar icons.
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Double-click on the A7Calib.exe icon to run the Wizard.
General Information Page
When you start the Alpha-7 Calibration Wizard, the first screen prompts you to enter:
Calibration Location— is important for calibration report documentation purposes.
Person performing the calibration— is the name of the operator/technician performing the
calibration. For names that are not in the pull-down list, new names can be added to the edit
field and will appear in the pull-down list the next time the Alpha-7 Calibration Wizard is run.
This means that if you have several people doing calibrations, that you do not need to type in
the information each time. Once it has been entered, the next time you just pull down the list
and choose the correct name.
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Next calibration is due on— is the calibration expiration date. The default date is 180 days
from the computer date setting at the time of the calibration. To change the due date, pull
down the calendar display and select the desired date. The Alpha-7 will post a warning status
of CALIB DUE seven days before the expiration date.
Altitude at this site— The elevation is the critical component of this page. The Alpha-7 uses
a correction factor based on the approximate air density at the elevation where the calibration
will take place. Because of the relatively short range of alpha particles in air, the elevation
plays a large part in where the gain should be set in order to display the alpha energies
correctly. Please note that the Alpha-7 does offer the choice of specifying the elevation in feet
or meters. Given that there is a factor of three between them, ensure that the correct altitude
units are used.
When the parameters have all been verified, click the Next > button to advance to the next
screen.
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Instrument Information and Isotope Configuration Page
Next, you must enter the Instrument Name of the Alpha-7 and its Eberline Serial Number.
Serial Number –this field accepts any text and shows up on the calibration report.
Instrument Name— is the name by which the Alpha-7 can be contacted over the network. If
you have changed the name of the Alpha-7 (using the Alpha-7 Client) then you must put the
new name in this field. For example, the name shown above is A7L000001. This is the
factory default name for serial number 001. The Instrument Name is displayed on Page 0 of
the Alpha-7 display. Enter the assigned Instrument Name in this field.
Once the Serial Number and Instrument Name fields have been entered, click the Connect
button to connect the Calibration Wizard to the Alpha-7.
If the address is incorrect, you will see the following message displayed. Click the OK button,
correct the name and try to connect again.
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Once connected, the page will change to look like the example below with the instrument
showing up in the Tree Control and the Smart Head fields enabled.
At this point, you can edit the remaining Smart Head fields.
Property ID— is the customer-assigned ID for the sampling head being calibrated. It can be
ant text up to sixteen characters in length.
Head Serial Number— is the Eberline-assigned serial number for the remote sampling head.
Air Gap— is the detector to filter spacing in millimeters. The default is factory-set and should
not be changed unless the detector to filter paper geometry is modified.
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Negative Bias— is the detector bias setting. Most Alpha-7s are shipped with negative bias
detectors to reduce the attraction of dust to a positively-charged detector surface. This setting
is for documentation purposes only.
After verifying all the above settings are correct, the user may modify instrument and/or
isotope parameters through the Tree Control.
Modifications using the Tree Control
Under the Alpha-7 Client, many of the edit fields are grayed out within the Tree Control
dialogs. When used within the Alpha-7 Calibration Wizard, the Tree Control allows broader
editing capability of Alpha-7 parameters and most of the edit fields allow editing. Some of
these fields which are applicable to the calibration of the sampling head are:
??
Alpha Threshold setting
??
Detector Bias voltage
??
Release Flow A/D Min/Max Scale
NOTE: Other fields which are enabled, pertain to the Alpha-7 display unit and must be
set by connecting to the actual instrument— not the display unit used to calibrate
remote sampling heads.
Some of the instrument fields for which editing is enabled are:
??
Sample and Release Flow Units
??
Fixed Flow
??
Fixed Flow Rate
??
Network Settings (TCP/IP Address, Mask, Computer Name)
When all Tree Control modifications have been completed, click the Next > button to proceed
to the next screen.
Source Information Page
The next Wizard screen is the Source Information page. This page is for specifying the
source used in the gain and efficiency calibration steps.
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The Calibration Source field is a drop down list of all the sources that have been defined.
Pull down the list and select the source to be used for the calibration. If the source is not in
the list, it will have to be added.
Source Considerations
The Calibration Source must be one of the isotopes which the Alpha-7 is monitoring. Note
that you can add the isotope using the Tree Control available on the previous Calibration
Wizard page and then remove it after the calibration. The isotope only needs to be present in
the Alpha-7 isotope tree during the calibration.
The source used should have a peak shape as sharp as possible. Thermo Eberline
recommends that a stainless steel source be used since the energy response is superior to
plated nickel sources. Nickel sources tend to have a broader and lower energy peak than a
stainless source and can cause calibration errors in the Gain setting.
Since the time required to perform the gain and efficiency calibration is dependent on the
source activity, a source activity of greater than 50,000 dpm is recommended— preferably an
activity in the range 100,000— 200,000 dpm. See the Options section for a list of Eberline
Calibration Sources.
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Note that the Alpha-7 uses a one inch (25 mm) diameter detector and the Calibration Wizard
produces much better results when using 25 mm diameter active-area sources (usually plated
on a 47 mm disk) than when using a source plated over the entire surface of the 47 mm disk.
This source geometry best represents the particle deposition pattern on the filter paper in
normal operation. When a larger active diameter is used, the particles outside of the 25 mm
center of the source have to travel farther than those inside the 25 mm center and as such
show up in the spectrum at lower energies - providing a broader and lower energy peak than
will actually be obtained using the filter paper. The filter paper is 47 mm diameter but the
collection diameter is only 25 mm.
Entering New Source Information
If the source to be used is not in the Calibration Source list, it will have to be added.
To add a new source, click the New button to enter the Source Details dialog shown below.
Choose the source isotope from the drop-down list. Note, all isotopes in the Alpha-7 isotope
database are listed, not just the isotopes in the isotope tree.
Serial No.— is an unique identifier which appears on the back of the source or on the source
container.
Source Geometry— defines the size of the plated area of the source. The recommended
plated area diameter is 25 millimeters.
Thickness— is the distance in millimeters by which the detector to filter air gap is reduced
when using the source. In most cases, the air gap will not change when using a source and
this value should be zero.
Source Activity— is the activity listed by the source manufacturer, or by the latest
recalibration of the source. Be sure to select the units of measure of the source activity in
dpm, cpm, or Bq (dps).
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Last Calibration— is the date the source activity was last calibrated. Shorter-lived isotopes
lose significant activity over time and must be recalibrated frequently. Source isotopes of long
half-life (e.g. Pu-239) do not usually require recalibration.
When all the Source Details have been entered, click the OK button to save the information
and return to the Source Information page. This information is then saved on the hard disk
allowing the source information to be entered once and then reused.
Editing Existing Source Information
If you click on the Edit button, you will see the same Source Details dialog as when adding a
new source, however, the source information for the selected source will be already entered in
the fields.
After the source information is edited, click the OK button to save the changes and return to
the Source Information page.
Once the Calibration Source field is correct, and the Source Details are correct, click the
Next > button to proceed to the next page.
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Gain Calibration Phase Page
The Gain Calibration Phase page shows the current spectrum in the Alpha-7. The display is
shown below.
You should now TURN OFF THE PUMP and put the calibration source into the source holder
and insert it into the Alpha-7. The spectrum display will reset and you will see the new
spectrum accumulating at the energy for the calibration isotope.
Once the source is in the Alpha-7, you click on the large Calibrate Gain button at the left side
of the display near the top. This will place the Alpha-7 in CALIBRATE status and begin the
gain calibration step.
NOTE: At any time in this process, you can stop the process using the “Cancel
Calibration” button and return to the previous screens. This is useful if for example
you notice you are using the wrong source.
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The Alpha-7 Calibration Wizard will set the gain to a relatively low number and you will see
the source peak start to grow in at the left side of the spectrum. Once the Alpha-7 has enough
counts for an accurate estimate of the peak location, the Wizard will reset the spectrum and
increase the gain to perform the high gain test. The source peak will now grow in at the right
side of the spectrum.
Once the Alpha-7 Calibration Wizard has determined the peak locations at the low gain and
high gain settings, it will calculate the gain required to place the peak in the appropriate
spectrum channel, given the known energy of the source isotope and the energy offset due to
the attenuation across the air gap at the defined altitude. It will then set the gain and offset
energy to the calculated values, reset the spectrum. The source peak should now begin to
grow in at the correct energy location.
NOTE: If you wish, at this point you may repeat the gain calibration by clicking the
Calibrate Gain button again. You may repeat this process until satisfied with the
results.
The Skip > button, which was displayed when the page was initially displayed, now reads
Next >. Click the Next > button to advance to the Efficiency Calibration Phase page.
Efficiency Calibration Phase Page
In the Efficiency Calibration Phase, the ratio of the detected source activity, to the known
source activity is calculated. This 4-Pi Efficiency value allows the Alpha-7 to scale the
measured activity and concentration levels to estimates of the actual activity and
concentration levels.
Since this phase is based on curve fit results— and not the actual gross count rate— a very
accurate curve fit must be determined. The spectrum must accumulate a significant number
of counts to produce an accurate fit, which is why a calibration source with a higher count rate
shortens the time required for this step.
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Click on the Calibrate Efficiency button to start the data collection which will compute the
intrinsic detector efficiency based on the source emission rate. At the end of the data
collection, the Alpha-7 checks the efficiency against the expected range of15% to 30%. You
will get an error message if the measured efficiency is outside of this range— usually
indicating a bad detector or that the Source Activity units were incorrectly specified in the
Source Details dialog.
At the completion of this phase, the Wizard will display the calculated 4-Pi Efficiency, and wait
for operator input. At this point, repeat the efficiency calibration again, if necessary, or
proceed to the next page.
NOTE: At any time in this process, you can stop the process using the “Cancel
Calibration” button and return to the previous screens. This is useful if for example
you notice you are using the wrong source.
When the Next > button is enabled, click on it to proceed to the Low flow measurement
phase.
Flow Calibration Page— Low Flow Measurement
After the Alpha-7 Calibration Wizard has completed the efficiency calibration, the next phase
is the flow calibration. Remove the source and replace the filter paper in the holder.
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At this point, the user is required to connect a pump or other source of vacuum to the outlet
connection of the Alpha-7, in series with a calibrated mass flow meter so that an accurate
known flow rate can be established. The Alpha-7 measures mass flow, which is independent
of the ambient air pressure in which the instrument is used. It is a measurement of the flow
based on the mass of the actual air molecules passing through the Alpha-7.
When calibrating the flow measurement of the Alpha-7, it is critical that the reference value
also be stated as mass flow, whether measured by an external mass flow meter or by any
alternate method which is then corrected manually for mass flow. This insures the use of the
proper reference, which is critical to the linearity and accuracy of the Alpha-7 flow
measurement.
The Alpha-7 calibration wizard performs a two point flow calibration, with the first point at a
point on the low end of the desired range of the flow and the second at a point on the upper
end of the desired range. The flow calibration is automatic, with no external or manual
adjustments to the Alpha-7 required. Flow to the mass flow sensor is controlled by a nonadjustable precision orifice, which uses the differential pressure across a fixed venturi to force
flow through the sensor.
The Calibrate to Ambient Flow checkbox should be checked if flow readings in ambient flow
(corrected for altitude) are desired. Selecting this feature can significantly affect the flow
readings and the calculation of concentration and dose rates at higher altitudes— based on the
actual vs. sea level barometric pressure— and result in proportionally lower levels!
NOTE: Mass flow must still be used in the calibration procedure. This checkbox does
not indicate that the input flow rate is in ambient units.
As shown in the screen below, the low flow calibration phase requires a flow rate of 0.5 cubic
feet per minute (CFM)— or its equivalent in the selected sample flow units— as shown in the
Mass Flow Reading window. Adjust the flow as directed on the instructions in the window and
click the Start button. The progress bar will indicate the time remaining in the measurement.
NOTE: The amount of time required to take the flow measurement is based on the
sample flow Window time, since the Window time is used to determine the number of
samples used in the flow rate average. Reduce the Window time to reduce the time
required for flow calibration.
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Click the Next > button when the measurement is completed to advance to the High Flow
Measurement page.
Flow Calibration Page— High Flow Measurement
The High Flow Measurement page is very similar to the Low Flow Measurement page.
Again, adjust the flow to match the value in the Mass Flow Reading window (1.5 cubic feet
per minute), and click the Start button. Wait for the flow measurement to complete and the
Next > button to be enabled. When the Next > button is clicked, the Wizard will calculate the
correct Min Scale and Max Scale flow calibration values and save them for use in the
Alpha-7. These values are displayed on the Measurement Results page.
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Results Page
The Measurement Results page shown below displays all the calibration parameters that
have been determined by the Alpha-7 Calibration Wizard. From this page, you can choose to
print out calibration report, or to skip the report. The summary of the parameters derived
during the calibration is shown at the left side of the display.
Click the Next > button to advance to the final page.
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Completion Page
The final screen of the Alpha-7 calibration process and stores all of the new parameters into
the Alpha-7. Clicking “Cancel”will abort the calibration and leave the existing parameters as
found in the Alpha-7. The calibration wizard may also be used to generate an as-found
calibration report by simply skipping all the steps in the calibration and printing out the report
at the end of the process.
At this point you can Finish running the Wizard program or click Repeat to calibrate another
Alpha-7.
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Data Logging
History Database— A7Log.mdb
The Alpha-7 has extensive data logging capabilities that are designed to archive readings for
later retrieval and analysis. The Alpha-7 uses two databases in its normal operation. Both
databases are ODBC-compliant and can be viewed using Microsoft Access or other database
software that can read a Microsoft Access database. Any version of Microsoft Access, from
Access 97 forward, can read the database files.
The Alpha-7 EberLogger.exe program stores history for status changes, spectrums, and
logged isotopes in a database called A7Log.mdb in the C:\Eberline\Alpha7\Data\History\
folder.
Creating A Link To The A7Log Database
Because the database is locked by the Alpha-7 Server program, it cannot be directly loaded
while the A7Server program is running. Instead, a remote user running Microsoft Access can
create a new database and link to the tables in the A7Log.mdb database.
??
Create a new blank database
??
Under the File menu, select Get External Data > Link Tables…
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??
Locate the Alpha-7 shared folder and then find the A7Log.mdb file in the History\ folder
??
When the Link Tables dialog displays, choose Select All, then click OK
The linked tables should now appear in the new database window. Save the new linked file
for future convenience. Opening the database the next time will automatically link to the
Alpha-7 database— and, any new data.
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Instrument Information Table
A InstrumentInfo table is contained in the A7Log.mdb database which contains information
to identify the Alpha-7 logging the data. This table contains only one record. The
InstrumentInfo fields are:
Instrument— is the Instrument Name
Location— describes the Alpha-7 location description
HeadSN— is the Eberline serial number of the remote sampling head
PropertyID— is the user-assigned property number of the remote sampling head
LastCal— is the date of the last calibration of the remote head
NextCal— is the calibration expiration date
Status Table
In addition to the isotopes, a record is kept of up to thirty-one days of Alpha-7 status changes
in chronological order. Records older than the maximum number of log days are deleted
from the table. The name of the status table is Status_Changes and it contains six fields:
UTC— is the time at which the status change occurred.
Status— is the new status.
The following fields can be blank if the alarm change was an instrument-level status change.
They will contain values if a new alarm occurred or if an existing alarm was cleared.
Isotope— identifies the isotope which caused the status change.
Reading— contains the latest isotope reading corresponding to the isotope-caused status
change.
AlarmLevel— indicates the alarm level which was exceeded to cause the alarm.
Units— is the units of measure to be applied to the Reading and AlarmLevel.
Isotope Tables
Within A7Log.mdb, the isotope data is logged into separate tables based on the isotope name
and the resolution of the data. For example, the 10-minute data table for Pu-239 is
“Pu239_10Min.” The resolutions are 1-minute, 10-minute, 1-hour and 1-day.
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Data is logged in a first-in-first-out fashion, with 240 entries for the 1-minute data, 144 entries
for the 10-minute, 168 entries for the 1-hour data, and 31 entries for the 1-day resolution. The
total size of the database is then limited by the total points accumulated during one month
and the number of isotopes being logged.
The four separate data resolutions are defined as follows:
Resolution
Calculation
Example Table
1-Minute
10-Minute
1-Hour
1-Day
Snapshot of on-the-minute reading
Average of ten 1-Minute averages
Average of six 10-Minute averages
Average of twenty-four 1-Hour averages
Pu239
Pu239_10Min
Pu239_1Hr
Pu239_1Day
Each entry in an isotope data table is time-stamped. The time stamp is usually in Universal
Coordinated Time (UTC)— also known as Greenwich Mean Time, or Zulu time— to avoid any
ambiguity in the log time for the data, allowing the data from any time zone to be properly
interpreted. For customers who request a time stamp in Local Time, a factory configuration
setting can produce time stamps based on the Local Time in the Alpha-7.
Each isotope table includes columns for:
UTC— This is the time stamp of the data in Universal Coordinated Time (or, optionally, in
Local Time).
Status— This field holds the isotope-level status— not to be confused with the
instrument-level status which holds the highest priority status of all the isotopes, and,
instrument statuses.
FastConcen— This field holds the fast concentration.
FastMDC— This field holds the fast minimum-detectible-concentration level.
FastDose— This field holds the fast dose accumulated since the filter change.
FastMDA— This field holds the fast minimum-detectible-activity.
SlowConcen— This field holds the slow concentration.
SlowMDC— This field holds the slow minimum-detectible-concentration level.
SlowDose— This field holds the slow dose accumulated since the filter change.
SlowMDA— This field holds the slow minimum-detectible-activity.
ReleaseRate— This field holds the slow stack release rate value.
SampleFlowRate— This field holds the sample flow rate
Volume— This field holds the total sampled air volume since the last filter change.
For each isotope, the units of the values in the database are the same as the units specified in
the Alpha-7 for concentration, dose, flow and volume. If the DAC Unity constant for an
isotope is not equal to one, the output values will be in DAC or DAC-h rather than the
radiological base-units.
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Spectrum Table
In order to provide data on the spectrum history, a table of spectrum snapshots is kept for
analysis. The Spectrum table contains six hours and thirty minutes of spectrum data.
Spectrums are saved every minute and include two records: one of the raw spectrum data;
and one of the fitted curve data.
Because of database table limitations, the 512-channel spectrums are condensed into
256-channel spectrums, which, while losing some detail, makes the database smaller. In
addition, the first twelve channels are also omitted since they are below the threshold and
never contain meaningful data.
The fields in the Spectrum table are:
UTC— is the time stamp of the spectrum records. Because each UTC filed must be unique,
the Raw Spectrum record is stamped one second prior to the Fit Spectrum record.
Status— is the instrument status at the time of the spectrum archival.
Type— indicates whether the record is the Raw Spectrum data or the Fit Spectrum. The
spectrums are archived in pairs: Raw, then Fit.
Total— is the total spectrum counts
Ch12… Ch510— is the combined counts for two channels. For example Ch12 is the counts
for channel 12 and channel 13; Ch510 is the counts for channel 510 and channel 511.
Spectrum Backup Tables
In the event an operator is not present for thirty minutes or more after an Alpha-7 alarm or
failure, thirty minutes after the alarm or failure, a backup copy of the Spectrum table is saved.
The backup table is saved with the name Spectrum_yyyymmdd_hhmm is a time stamp
indicating the backup time, where yyyy is the year, mm is the month, dd is the day of month,
hh is the hour and mm is the minute. For example, the spectrum backup which occurred at
2:17 PM on March 19, 2002 would be saved as Spectrum_20020319_1417.
The backup table has the same fields as the Spectrum table.
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Starting A New History Database
In the event that the user wishes to start with an empty database, a database template is
included in the History\Empty Database folder. The user must shutdown the Alpha-7 Server
and EberLogger programs, which may be using the database and prevent access by external
programs. The user may then copy the A7log.mdb from the History/Empty Database/ folder
to the History database to create a blank database for the Alpha-7 to use. If no database is
available in the History folder, data will not be logged.
Disabling Data Logging
Data logging may be disabled by preventing EberLogger.exe from executing during the
startup process. The Startup.bat batch file executes EberLogger during initialization of the
Alpha-7. Disable logging by commenting out the line as follows:
REM start eberlogger
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Troubleshooting
This section is intended as a brief outline of possible solutions to common configuration
problems. Many initial setup problems are associated with network incompatibilities.
Solutions to networking problems are outside the scope of this manual and the user should
consult their Network Administrator for help in solving the communications or Network
Security problems.
Curve Fit Problems
Symptom
Possible Cause
Solution
All or most fit peaks do
not line up with spectrum
peaks
Missing radon daughter isotope
causes nearby peak to shift to
best fit the spectrum
Identify and add the missing
radon daughter to the
isotope tree
Calibration offset or gain is off
1. Check for correct altitude
during calibration
2. Calibration source is
coated or annealed resulting
in shifted peak. Use stainless
steel source
3. Source Thickness
parameter should be zero
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Single fit peak does not
line up with spectrum
peak
Missing isotope
1. Check actual peak energy
and compare to other
possible isotopes for the
monitoring environment.
2. Po-216 (5.3 MeV) is
sometimes needed in the
isotope tree.
Peaks are in correct
location but peak shape
does not match fit curve
Insufficient “training”or filter type
has changed
Allow Alpha-7 to “train”itself
to the peak shape with a
clean filter until 80,000
counts and Fit Ratio < 0.60
Fluoropore filter installed with
fiber-backing toward detector
Install Fluoropore filter
papers with fiber-backing
(black side) down.
Peaks look good initially
but drift off after several
days
Dust loading causes peak
smearing
Change filter paper more
often.
Unknown counts in low
energy channels
Low Threshold
Raise Threshold to at least
1mV or 2.5 MeV
Light leak
Check door switch to verify
that detector voltage is off
when door is opened.
Non-Fluoropore filters have
broader peaks
Use Fluoropore filters
Peaks will be broader at Sea
Level, than in Santa Fe, NM
(elev. 6500 ft)
None
Peaks much broader
than examples in manual
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Alarm Problems
Symptom
Possible Cause
Solution
Alpha-7 is false alarming
Po-212 is set as a Reference
isotope
Check Isotopes.mdb
database for a Reference
checkmark on Po-212. Clear
the checkmark, save the
database, delete Po-212
then re-add the isotope.
Insufficient “training”or filter type
has changed
Allow Alpha-7 to “train”itself
to the peak shape with a
clean filter until 80,000
counts and Fit Ratio < 0.60
Will not alarm on check
source
Low activity check source was not
inserted before filter change was
sensed. Sensitivity increases for
up to 2 Slow Window times after
a filter change.
Insert the source rapidly (in <
10 seconds) to avoid filter
change detection.
Concentration alarm
goes away on check
source test.
Check source is a fixed-activity
event resulting in a spike in
Concentration. It is normal for the
alarm to clear after there is no
longer a change in count rate.
Check for Dose Alarm
instead of Concen Alarm.
Symptom
Possible Cause
Solution
Status does not clear
Latching statuses
Press the Alarm Ack. button
or Acknowledge Alarm from
remote Alpha-7 Client
POOR FIT status
See Curve Fit Problems
OUT OF CALIB status
Calibration has expired
Status Conditions
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FILTER DIRTY status
Alarm level is too low for the filter
change frequency
Raise alarm level or change
filters more frequently
Heightened radon levels due to
meteorological disturbance
Change filter paper
Detector failure
Use check source to
determine if detector is
counting.
Very low radon levels
Set Filtered Air checkbox to
lengthen timeout duration.
MCA EEPROM status
New MCA Board or uncalibrated
remote head
Calibrate head. If problem
persists, change out MCA
Board.
DOOR FAILURE status
Detector door left open
Close door completely
Door switch is not closing
Replace door switch
Symptom
Possible Cause
Solution
D/A Output does not
track the reading on
Page 1
Factory setting for Output Slow
Reading does not match reading
on Page 1
Output Fast Reading is the
default. Make the Fast
reading display on Page 1.
No output on D/A
Display Board configured for
current loop
Check Display Board
configuration
D/A output scale does not match
range of readings
Verify Min Scale and
Decades match the current
units and range of display
values.
LOW COUNTS status
D/A Output Problems
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Logging Problems
Symptom
Possible Cause
Solution
Error message when
trying to open
A7Log.mdb
File is locked by A7Server.exe
Use New database and link
to Alpha-7 database tables.
(See Logging section)
No logging of data
EberLogger is commented out in
Startup.bat
Check Startup.bat and
uncomment “start
eberlogger”command.
Database is missing
Verify A7Log.mdb is in the
Data\History folder. If not,
copy the file from the Empty
Database\ folder.
Data Source points to different
file or location
Check the Data Source
setting (see Logging section)
Alpha-7 date/time is much older
than data in database
Check date/time of data in
database and in Alpha-7.
Resynchronize clock and/or
delete data from A7Log.mdb
if necessary.
Symptom
Possible Cause
Solution
RadNet readings do not
match displayed
readings
Conversion to Bq is not correct
for the units
Check RnIsotopes.txt file to
make sure conversion
constant for isotope is
correct.
RadNet Client supports only one
logged isotope
Specify one isotope to log.
RadNet Problems
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Hardware Description
Remote Sampling Head Hardware
Detector and Preamp Board
The alpha sensitive detector used in the Alpha-7 is a 490 mm2 diffused junction detector.
Negative bias detectors are standard to reduce contamination on the detector face. The
detector is mounted on the preamplifier board. Jumpers on the MCA Board control the bias
voltage polarity and sets the amplifier pulse output polarity positive-going for input to the flash
converter. The front surface of the negative bias detector is at ground potential, and it is at
positive bias potential for the positive bias detectors.
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MCA Board
The MCA Board performs continuous 4096-channel data acquisition, which is binned down to
512 channels, and supplies that data to the SBC via the RS-485 link on the Display Board. It
also samples the sample flow and stack flow analog input signals and converts them using
two A/D converters. The SBC requests a complete spectrum from the MCA Board once each
second.
The MCA Board uses flash converter and computer-adjustable-gain amplifiers. The detector
bias voltage supply section is a computer-controlled DC-DC converter, which supplies up to
60 Vdc positive and negative (polarity jumper selectable). A two channel 10-bit A/D converter
is used to monitor the sample and stack flow signals. An on-board mass flow sensor is used
for monitoring sample flow through the sampling head.
The MCA Board also supports computer-adjustable-gain, bias voltage and threshold, allowing
the Alpha-7 Calibration Wizard to align and scale the spectrum properly. A two-point energy
calibration is provided in the Alpha-7 Calibration Wizard to set the span of the spectrum and
to compensate for peak offset due to filter-to-detector air gap.
The photograph shows the:
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??
sampling assembly with the mass flow sensor (connected to the clear tubing)
??
MCA Board - attached to the sampling assembly
??
CAM mechanism for closing the door located underneath the vertical tube.
Mass Flow Sensor
The Alpha-7 uses a hot wire anemometer to measure the airflow that passes through the
monitor. This mass flow measurement technique is independent of pressure and temperature,
making it more accurate than a rotameter. The regulations for alpha air monitoring are
typically expressed in terms of ambient volumetric flow rates, however, requiring a correction
for density altitude at the measurement location.
Display Board
The display board provides the interface between the SBC and the vacuum fluorescent
display and the alarm annunciation. This includes the relays for alarms and failures, the lights
for high alarm, alert alarm (Hot Job and Trouble on Alpha-7L units) and normal, as well as the
Sonalert audible annunciator and the red beacon on top of the Alpha-7.
The SBC provides output information to the display board once each second . The display
board then drives the 2x20 character vacuum fluorescent display with the commands from
the SBC and drives alarm lights, horn, relays and drives the 0-20, 4-20 or 4-24 mA (as
defined by a jumper on the board) D/A output. The interface between the SBC and the
display board is a 115,200 baud serial port.
The interface between the Display Board and the MCA Board is a 115,200 baud RS-485
serial port. Messages from the A7Server program are “passed through”the display board, out
the RS-485 port and on to the MCA board. Responses from the MCA board are again passed
through, back to the SBC.
Alpha-7A Details
Connections are available on the display board for the concentration/dose alarms,
concentration alert, and normal relays, and also for the analog signals for the analog output of
concentration or flow.
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Alpha-7L Details
Connections are available on the display board for the concentration/dose alarms, trouble,
and failure relays, and also for the analog signals for the analog output of concentration or
flow.
Internal Single Board Computer (SBC)
The PC used is a single board computer
(SBC) with a 233 MHz Pentium class
processor (Cyrix GXM-233) and 64 MB
of SODIMM SDRAM. The SBC has onboard support for local-bus SVGA
graphics (industry standard DB15
connector), 16-bit Ethernet
communications (100-Base-T using an
RJ45 connection), and a single 9-pin
mini-DIN connector (PS2 type) for
keyboard and/or mouse. An IDE hard
drive (size varies, > 3 GB) is used for the
software.
The Windows NT 4.0 operating system is installed with full support for plug and play devices.
Optional support for PCMCIA cards is also offered.
While computers are constantly being upgraded, and Thermo Eberline will use the latest
technology as it becomes available, the single board computer used in the Alpha-7 currently
has the following specifications:
Processor
233 MHz Pentium class; Cyrix GXM-233
RAM
One 144-pin SODIMM socket accepting up to 128 MB SDRAM. Typically
the Alpha-7A will have 64 MB installed
Hard Disk
EIDE Hard drive interface supporting up to 2 EIDE devices. The PC
supports BIOS auto-detect.
Serial Port
The SBC is supplied with one RS-232 serial port and one
RS-232/RS-422/RS-485 port. One RS-232 port (COM 2) is used to
communicate with the Display board. The other port (COM 1, DB-9
connector) is available through the side panel.
Video
CRT resolutions up to 1280 ? 1024 @ 256 colors
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Ethernet
PCI 10/100 Mbps 100 Base-T RJ-45 Ethernet, compatible with the IEEE
802.3 protocol.
WiFi
(optional)
IEEE 802.11b wireless Ethernet (WiFi) output using off-the-shelf PCMCIA
cards
The following features are available in the SBC but are not implemented in the current
Alpha-7 are:
??
Audio support
??
FDD - support for up to 2 floppy disk drives
??
Parallel - a single parallel port supporting SPP/EPP/ECP parallel modes
??
infrared communications port
??
USB support; support for solid state disks
??
support for a flat panel display
??
support for the PC/104 expansion format
Stack Inlet and Sampling Collection Efficiencies
The In-Line Sampling Head allows the same configuration to be used for either room air
monitoring or sampling from stacks or ducts. The unit was tested with 10 µm aerodynamic
diameter aerosols and 100% collection efficiency was measured.
The Radial-Entry Sampling Head is used for room air monitoring. The unit was tested with
10 µm aerodynamic diameter aerosols and 100% collection efficiency was measured at 1
CFM flow rate.
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Self-Diagnostics
Hardware Self-Diagnostics
When the Alpha-7 is first powered up, the Display Board tests each of the alarm and the
status lights, the beacon, and the Sonalert.
Software Self-Diagnostics
During the normal operation, the Alpha-7 Server software constantly (once each second)
calculates the MDC (Minimum Detectable Concentration) and MDA (Minimum Detectable
Activity) and compares it to the alarm levels for concentration and dose. If the sensitivity is
not sufficient to measure the proscribed levels, the Alpha-7 flashes the Normal light, reports
an isotope status of BELOW MDC/MDA, and on the Dose Control report in the Alpha-7 Client
highlights the isotope in white. When the MDC is below the alarm level, the isotope row is
highlighted in green.
Each time a curve fit is performed on the spectrum, a goodness-of-fit parameter is evaluated.
If the quality of the fit is “bad”for 20 consecutive measurements, then the POOR FIT status is
posted and the unit goes into a failed condition.
As the spectrum becomes more defined over time, the MDC and MDA levels will improve.
However, as the filter begins to load, the minimum-detectable levels will reach a minimum
then begin to rise again. Once the MDC or MDA rises above the proscribed alarm level, and
the filter has accumulated for at least 24 hours, a FILTER DIRTY status will be posted.
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Options
Radial Head Sampling Head
Order Part No. ALPHA7 OPT2
In-Line Head Sampling Head
Order Part No. ALPHA7 OPT3
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In-Line Head Filter Tray Assembly
Order Part No. YP11653044
In-Line Head Source Holder
Order Part No. YP11653054
In-Line Head Sample Line Adapter
Adapter, air inlet tube – Alpha-7 requires 1.25 inch Swagelok fitting to mate to 1 inch stainless
sample lines.
Order Part No. ZP11653053
Remote Head Communications Cable
This cable, for connecting the Alpha-7 to a Remote Sampling Head, is available in a three
and ten-foot lengths and is compatible with both the Radial-Entry Head and the In-Line Head.
3-ft Cable:
Order Part No. CA-134-03FT
10-ft Cable:
Order Part No. CA-134-10FT
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Fluoropore Filters
This is the recommended filter for use in the Alpha-7. Millipore 5µm Fluoropore filters with
black backing. Box of 100.
Order Part No. FIFP15
Plutonium Calibration Source
Pu-239 Alpha standard, 1-7/8 In. diameter stainless steel disk with 1-Inch active area. Activity
of 20,000 to 45,000 CPM (0.009 to 0.02 µCi). Certificate of Calibration traceable to NIST is
supplied.
A specific license from the NRD is required, either by the customer or by the shipper. The
customer must have a license.
Order Part No. DNS-17SP
Thorium Calibration Source
Th-230 Alpha standard, 1-7/8 In. diameter stainless steel disk with 1-Inch active area. Activity
of 20,000 to 45,000 CPM (0.009 to 0.02 µCi). Certificate of Calibration traceable to NIST is
supplied.
A specific license from the NRD is required, either by the customer or by the shipper. The
customer must have a license.
Order Part No. DNS-17ST
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PCMCIA Adapter
This option provides and adapter which mounts on the SBC to support PCMCIA cards.
Currently, the only card supported by the Alpha-7 is the Orinoco Gold wireless Ethernet card
for use in wireless Alpha-7 networks.
Order Part No. Alpha7L OPT1
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Spare Parts
Alpha-7 Spare Parts Listing May 2001
Item
Part Number
Description
Location
1
ADSS2
SC628W Sonalert
Bottom plane of Alpha-7 case
2
CYDE8N
CYDE8N 490 mm2 diffused junction detector, configured for negative bias
Inside in-line detector housing
3
FGBR3
5/16 Hose ? 1/8 MPT
4
FGBR68
Hex Coupling 1/8 FPT
5
FGPL40
1/8MPT ? 1/8 Hose Elbow
6
FGPL53
#10-32 ? 1/8 Hose Orifice, .016 dia.
7
FGPL60
1/8 MPT x 10-32 UNF Reducer Fitting
8
FUST2
Fuse, 1 A, 250V, 5 x 20 mm
9
LPAS32
Strobe Light, Red, 12 VDC
10
MEVE263
Wide Input Power Supply
11
MMBZ35
Hole Plug - 3/4 Inch - Black Plastic
12
MMRU78
Bumper
14
MMTU1
1/8 ID ? 1/4 OD Clear PVC Tubing
15
MMTU2
5/16 ID ? 9/16 OD Clear PVC Tubing
16
OPDE5
Optical Sensor, 0.125 Gap
17
ORBN2010
2-010 BUNA N OR Neoprene O-Ring
18
ORBN2025
2-025 BUNA N OR Neoprene O-Ring
19
ORBN2027
2-027 BUNA N OR Neoprene O-Ring
20
ORBN2031
2-031 BUNA N OR Neoprene O-Ring
21
ORBN2033
2-033 BUNA N OR Neoprene O-RING
22
ORBN2132
2-132 BUNA N OR Neoprene O-Ring
23
ORBN2132
2-132 BUNA N OR Neoprene O-Ring
On top of Alpha-7 case
Filter holder
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Item
Part Number
Description
24
ORBN2227
2-227 BUNA N OR Neoprene O-Ring
Location
25
SGCO57
Compression Spring - .30 OD, .63 Long
26
VEIN49
3.5 in. Hard Disk Drive, EIDE, >3 GB
27
VEIN82
Single Board PC, GXM-233 processor, 64 MB SODIMM RAM
29
YP11649054
Alarm Ack Switch Harness
30
YP11653044
47MM Filter Tray Assembly
31
YP11653072
Alpha-7 Display Board
32
YP11653082
Alpha-7 Preamplifier Board
33
YP11653092
Alpha-7 MCA Board
34
YP11653094
Display Power Harness, Alpha-7
35
YP11653095
Computer Power Harness, Alpha-7
36
YP11653099
Sonalert Harness, Alpha-7
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Drawings
Alpha-7 Outline Drawing
Hot Job
Trouble
Alarm Ack.
Display Scroll
Normal
Central Module Outline, Alpha7L, 11653165A
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C3
CR1
C7
Preamplifier Schematic
C4
R6
R4
C2
U1
R1
R7
C5
R2
R3
Q1
R5
C1
C6
J1
PreAmp Board Schematic, Alpha7L, 11653080A
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Preamplifier Assembly
J1
COAX
PreAmp Board Assembly, Alpha7L, 11653152A
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MCA Board Schematic
MCA Board Schematic, Alpha7L, 11653134A sheet 1 of 3
120
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MCA Board Schematic, Alpha7L, 11653134A sheet 2 of 3
121
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MCA Board Schematic, Alpha7L, 11653134A sheet 3 of 3
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MCA Board Component Layout
ATTENTION
MCA Board Assembly, Alpha7L, 11653136A sheet 1
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Display Board Schematic
Display Board Schematic, Alpha7L, 11653131A sheet 1 of 2
124
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ALPHA-7 TECHNICAL MANUAL
Display Board Schematic, Alpha7L, 11653131A sheet 2 of 2
125
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Display Board Component Layout
ATTENTION
Display Board Assembly, Alpha7L, 11653133A
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Alpha-7 Remote Head Communications Cable
CA-134-03FT Module Connecting Cable, Alpha7L, 11653145A
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RAP-1 Vacuum Pump
The model RAP-1is a compact, portable system containing an oilless vacuum pump, motor
and air flow regulator. The Thermo Eberline airflow regulator is designed to maintain a
constant pressure drop across an in-line orifice by controlling a variable bypass valve into the
pump. The orifice is adjustable, permitting flow rate adjustment from near zero up to the
maximum pump flow velocity. This flow control system permits the pump to operate at a
minimum pressure drop at all times which provides cooler pump operation to extend the
lifetime.
Some RAP-1 operating curves are shown below. The top line is the pump operating curve.
The curves below the pump operating curve show how the sample inlet flow varies with intake
vacuum for two different regulated settings. After the regulator is set at a particular inlet flow
rate, the sample flow rate follows a similar curve, decreasing as intake vacuum increases.
RAP-1 Specifications
Physical Specifications
Pump type
Oilless, carbon vane
Motor
1/4 HP, 115 Vac, 60 Hz, 6 A (220 V, 50 Hz version available)
Vacuum
19 inches at sea level
Flow rates
See figure 1
Size
17.75 inches long by 7 inches wide by 9.25 inches high (45.1 ? 17.8 ? 23.5 cm)
Weight
33 pounds (15 kg)
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Available Accessories
PURK3
RAP-1 Pump Repair Kit
RAP1R RK1
Regulator Repair kit
RAP1 RK2
Pump and Regulator Repair Kit
??
PERFORMANCE CURVES, RAP-1 PUMP
3.4
3.2
3
2.8
Pump Ope rating Curve
2.6
2.4
2.2
Operating Curve, 2.12 SCFM
2
1.8
1.6
1.4
1.2
Oper ating Curve, 1.06 SCFM
1
0.8
0.6
0.4
0.2
0
0
2
4
6
8
10
VACUUM (in Hg)
130
12
14
16
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THERMO EBERLINE
ALPHA-7 TECHNICAL MANUAL
Operating Instructions For RAP-1/RAS-1
The Thermo Eberline Model RAP-1 consists of a vacuum pump and an airflow regulator. The
RAS-1 is essentially a RAP-1 with an airflow indicator, vacuum gauge and a filter paper
holder added.
To use the RAP-1, remove the two dust caps on the regulator portion of the pump, one
located on the fitting marked AIR IN, the other located on the jar assembly of the bypass air
inlet. Connect a line or hose to the fitting on the regulator marked AIR IN. The desired airflow
may then be set by adjusting the screw in the side of the regulator body marked FLOW
ADJUST. To increase the flow, turn the screw counterclockwise and to decrease flow, turn it
clockwise.
To use the RAS-1, remove the dust plug located on the jar assembly of the bypass air inlet.
Remove the plastic cover from the filter paper holder. Remove the paper clamp by turning
the outer ring counterclockwise. Remove the holder and replace the clamp by turning the
outer ring clockwise. Turn on the pump and observe the flow rate on the flow meter. If an
adjustment is desired, change the flow as described in the paragraph above. The observed
airflow reading vs. the actual airflow will differ except under ideal conditions, which are rarely
encountered. The actual flow can be obtained by multiplying the flow rate on the flow meter
by the square root of the absolute pressure at the inlet to the flow meter (this is the sum of the
atmospheric pressure minus the vacuum as read on the gauge) divided by 29.92 inches Hg
(atmospheric pressure at sea level).
When using the RAP-1 and RAS-1, do not attempt to control airflow with an external valve in
the line. This will defeat the function of the regulator and will cause the pump to work at
maximum power, which will, in turn, cause it to run hotter and shorten the pump life. Do not
close off the AIR BY-PASS line of the regulator.
Theory of Operation For RAP-1 Regulated Air Pump
The performance curves for the RAP-1 pump/regulator are shown in Figure 1. The regulator
can be set for small sample flow rates with negligible head loss added to the system. This is
accomplished by the introduction of bypass air into the stream. The bypass air allows the
pump to operate at its maximum capacity. The additional air that is drawn through the bypass
port causes the pump to run cooler and thus increases the life of the pump. As indicated in
Figure 1, the sample flow rate will remain fairly constant over the wide range of external head
losses (increasing vacuum) that would be caused by plumbing, filter loading, or elevation
above sea level.
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A cross section of the regulator is shown in Figure 2. The following explains briefly how the
bypass valve on the regulator works.
Air flow into the sample air inlet passes through the variable orifice, causing a pressure drop
across that orifice. Each side of the orifice is vented to corresponding sides of the diaphragm,
so that the pressure drop positions the diaphragm across the orifice.
Attached to the diaphragm is the bypass valve. With the adjusting screw set to the position
for the desired sample flow, the pump draws air from both the sample and bypass inlets. As
the sample flow decreases (as would be the case when the filter paper loads up with particles)
the pressure drop across the orifice decreases. This results in a repositioning of the
diaphragm as the force of the spring is now more than the force created on the diaphragm by
the pressure drop on the orifice. The spring pressure on the diaphragm causes the bypass
valve to close slightly allowing less air to flow into the bypass inlet. Since the pump is
operating at the maximum flow as the bypass flow decreases the sample flow increases,
returning to near the preset flow rate. Thus for a given sample flow rate (as set by adjusting
the orifice) as the sample flow rate is changed, the diaphragm moves to open or close the
bypass inlet. This increases or decreases the bypass flow, which in turn decreases or
increases the sample flow, reestablishing the preset value.
As with most regulators systems, the RAP-1R is not ideal. As the sample flow decreases (as
measured by increased vacuum at the sample inlet) the adjustment of the regulator to
reestablish the sample flow rate leaves the flow slightly lower than the original value. Refer to
the performance curves, which show two sample flow rates. As the vacuum increases the
flow value moves along a path shown by the typical values of 60 and 30 lpm. If it is desired
to maintain a flow value + or - a given tolerance, one recommendation is to start the flow at
the desired value + the tolerance. As the filter loads up, the flow will decrease to the value the tolerance. This provides an average flow rate of the desired value over the period of filter
loading.
Maintenance
A. Vane Replacement: The hard carbon vanes should be replaced after 6,000 hours of service.
All four vanes should be replaced at the same time. In order to replace the four vanes,
remove the inlet and outlet filters on the muffler box of the pump. Next, remove the 5 bolts
from the muffler box.
When removing the muffler box, take a look at the gasket sandwiched between it and the end
rotor shield plate. Replace the gasket if necessary. Next, remove the 6 bolts on the rotor
shield plate. Use compressed air to clean out the pump chamber especially if a vane has
broken. Do this prior to inserting new vanes. Remove the four vanes behind the shield plate,
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noting their edge curvature orientation. Put the new vanes in the same way. Re-torque the
six bolts on the end rotor shield plate with a torque not exceeding 100 in-lbs.
Sometimes when a vane breaks a piece will wedge between the top of the rotor and the body,
opening the top clearance. The top clearance should be .002 inches. This can be checked
with a feeler gauge. The rotor should be turned while checking this clearance so that all
points on the circumference of the rotor will clear. To reduce the top clearance to .002 inches,
tap LIGHTLY on the top of the body with a miniature hammer.
DO NOT at any time remove the rotor. DO NOT loosen bolts on either the body or mounting
bracket, because this will destroy the preset clearance between the rotor and these parts.
B. Cleaning: If the pump is permitted to run with a dirty filter or no filter at all, excessive dirt,
foreign particles, moisture and possibly even oil (from vapors in surrounding air) could
accumulate in the chamber. Any of these could cause the vanes to act sluggish or even
break.
Flushing the pump (see below) should take care of these situations, but if not, remove the end
plate for further examination.
C. Flushing: This is accomplished by removing the filter assemblies and adding several
teaspoons full of *cleaning solvent at the intake while the pump is running. Repeat the
flushing procedure again and, after all the solvent has passed through the pump, replace the
filters. Flush the pump several times a year.
To clear the filter and muffler felts, brush off excess dirt, lint, etc. Wash in cleaning solvent9
and dry before installing.
9
Recommended Solvent: Gast Flushing Solvent, part number AH255. Flush unit in a well-ventilated area. Use eye
protection and keep your face away from the exhaust port. Do not use a flammable cleaning solvent, such as kerosene.
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Model RAP-1 Parts List
Item
1
2
3
4
5
Part Number
PUVA1
PUHD43
PUHD44
PUHD45
PUHD46
Description
Pump
Filter Felt
Gasket
Muffler
Vanes
Use
6
7
8
9
10
11
12
PUDH24
PUHD3
PUHD5
PUDH26
RAP1R
ZP10552007
ORTF2008
13
ORBN2007
Jar Assembly
Jar
Filter Felt
Jar Gasket
Regulator
Diaphragm
2-008 O-Ring Teflon, 3/16" id5/16"
OD
O-Ring, Buna-N or Neoprene,
Parker 2-007, 5/32" id x 9/32 O.D.
for RAP
For Pump
For Pump
For Pump
Hard Carbon, For Pump,
buy in quantities of 4
Bypass Air Water Trap
For Water Trap
For Water Trap
For Water Trap
For RAP-1R
For RAP-1R
Model RAP-1/RAP-1R Repair Kits
1.
Pump Repair Kit, Thermo Eberline Part No. PURK3 contains:
Description
Filter Felt
Gasket
Vanes
2.
Quantity
2 ea
1 ea
4 ea.
Thermo Eberline Part No.
PUHD43
PUHD44
PUDH46
RAP-1R Repair Kit, Thermo Eberline Part No. RAP1R RK1, contains:
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Description
Neoprene O-Ring
Diaphragm
Teflon O-Ring
3.
Quantity
1 ea
1 ea
1 ea
Thermo Eberline Part No.
ORBN2007
ZP10552007
ORTF2008
RAP-1 Repair Kit, Thermo Eberline Part No. RAP1 RK2, contains:
Description
Pump Repair Kit
RAP-1R Repair Kit
Quantity
1 ea
1 ea
135
Thermo Eberline Part No.
PURK3
RAP1R RK1
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