783620H / 1013 5. MENU COMMANDS
Create PBC...
This feature analyzes an existing
.UFO
file and creates a corresponding
.PBC
file. It operates in both buffer and Detector windows.
Browse for the Background Ufo
file to be used (Fig. 155). Then, either enter a new filename for the
.PBC
file or select an existing
.PBC
file (the current contents of the file will be overwritten). Note that at startup GammaVision automatically
Fig. 155. PBC Wizard.
attempts to load the PBC table last used. It stays resident in memory as the working or internal
PBC file once loaded. You can replace this file at any time using Select PBC....
As of v7, Create PBC... now adds the unknown peaks to the PBC table. A new nuclide,
Un-0
, has been added to the library, and its peak list is assigned all of the unknown peaks with uncertainty values less than the Peak Cutoff value set on the Analysis tab under Analyze/Settings/
Sample Type.... These peaks are used in the PBC calculation if the PBC correction’s Match
Width by Energy checkbox is marked on the Corrections tab. Figure 156 shows a PBC table file with all unknown peaks attributed to nuclide
Un-0
.
Select PBC...
Use this command to open a standard file-open dialog and select a new working
.PBC
file. If a
.PBC
file is already loaded, its name will be displayed in the File name field; otherwise, the default,
*.PBC
, will be shown. Select the desired file and click Open. The
.PBC
files are organized by nuclide, then by peaks, for each nuclide.
Edit PBC...
This function is used to create a new
.PBC
file or to change the contents of an existing
.PBC
file.
To create a
.PBC
file, click Edit PBC... to open the Editing dialog shown in Fig. 157.
Figure 158 shows this dialog’s control menu (click the title bar icon to open it). It contains several of the commands necessary to create and edit
.PBC
files.
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Fig. 156. PBC Table File Displaying Peaks for Nuclide “Un-0.”
Manually Creating a New PBC Table
Open the control menu and click New. This will clear the Edit window so nuclides can be entered manually. Click on the Insert... button to open the dialog shown in Fig. 159. Enter the
nuclide name exactly as it appears in the library.
Now, in the peak (right-hand) section of the dialog, click Insert... to open the dialog in Fig. 160.
Enter the energy of the gamma ray, the peak activity in cps, and an optional 1-sigma uncertainty between 0% and 1000%. The energy must be the same as the library value. Peak energies in the
PBC Table and not in the library for this nuclide will not be corrected; likewise for peak energies in the library and not in the PBC Table for this nuclide.
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Fig. 158. Edit PBC Dialog Control
Menu.
Fig. 157. PBC Table Editing Dialog.
Fig. 159. Edit or Manually
Add Nuclide Name.
Fig. 160. Edit PBC Peak Values.
Automatically Creating a PBC Table
To make a
.PBC
file from the background spectrum analysis results (
.UFO
) file, the background count rates are extracted from the analysis results file and inserted in a
.PBC
file. To do this, open the control menu and click on Show Background Analysis.... This will open a standard file-open dialog. Select the correct
.UFO
file and click Open. The list of nuclides in the analysis will be displayed to the left of the PBC Table (see Fig. 161). If no peaks are shown, none were in the analysis file, possibly because they were all outside the energy analysis range.
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Fig. 161. The List of Analysis Nuclides (left) and the PBC Table (right).
Adding Nuclides
There are two Insert buttons at the bottom of the PBC nuclide list: Insert..., which is for manually specifying the nuclide; and the button below it, which will be labeled with the name of the nuclide selected in the analysis results list (when no nuclide is selected, this button is labeled
Insert Copy).
To automatically add an analysis nuclide to the PBC list: Go to the analysis results list and click once on the nuclide of interest. This will activate the gray Insert Copy button at the bottom of the PBC list, and change its label to Insert plus the name of the nuclide. Now, in the PBC list, locate the nuclide immediately below the desired insertion position, then click Insert [nuclide
name]. This will insert the nuclide, and display the energies and backgrounds for its peaks in the analysis.
Double-clicking on a nuclide in the analysis results list will insert it into the PBC list immediately above the highlighted PBC-list nuclide.
To manually add a nuclide to the PBC list, locate the nuclide immediately below the desired insertion position, and click once to highlight it. Next, click the manual Insert... button to open the dialog shown in Fig. 159, then follow the manual nuclide and peak insertion instructions that begin on page 176.
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The entire analysis nuclide list can be copied to the PBC list by opening the analysis list’s control menu (Fig. 162) and selecting Copy All to PBC.
To change the name of a nuclide on the PBC list, double-click it to open the PBC Nuclide dialog
(Fig. 159).
To remove a nuclide from the PBC list, click the nuclide, then on Cut. This will remove the nuclide from the list. In addition, it will activate the gray Paste button at the bottom of the PBC list, and change its label to include the name of the cut nuclide. This is illustrated for
152
Eu in
Fig. 163.
Fig. 163. Cut Nuclide Ready to Paste.
Fig. 162. Control Menu.
Rearranging a PBC List (Optional)
The order in which nuclides appear in the
.PBC
file does not matter. However, if you wish to rearrange the list for ease of reading, you can do so by cutting and pasting.
Peak Editing
When a nuclide is selected in the working
.PBC
file, the right half of the Edit PBC dialog shows the peak list. Note the column headers, Rank, Energy, and C.P.S.. To sort the peak list by a particular parameter in the list, click the appropriate header.
To edit a peak, either double-click the peak in the right-hand list, or click it once then click the
Edit button. This will open the PBC Peak dialog (Fig. 160).
Use the same PBC Peak dialog to add a peak: click the peak just below the desired insertion point in the peak list, then click Insert.... This will open the PBC Peak dialog. Enter the energy and counts for the peak and click OK.
Peaks can be deleted with Cut and, for easier readability, moved with Cut/Paste. The order of the peaks is not important and has no effect on the correction.
Several peaks can be cut at one time from the list, then pasted back into the list into a different order. Cut peaks remain queued up for pasting, last one first. Each relocated peak will be
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