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All of the peak calculations use the Analyze/Settings/Sample Type... values; see
Section 5.5.1.1. This is to ensure that the calibration and analysis calculations are the same. Be sure to check the settings before starting the wizard; several of these settings are important. If spectrum has high dead time, there will also be a significant amount of random summing. The correction for random summing is applied in the calibration calculations. The Random Summing factor is discussed in Section 6.11 and entered on the
Sample tab under Analyze/Settings/Sample Type.... The starting channel of the Analysis
Region should be set above the low-level cutoff. The peak-cutoff sensitivity used in the calibration is the smaller of the following: 10% or the value entered on the Analysis tab.
Note also that the net peak area calculation can be affected by the library match width, as specified on the System tab. Before calibrating, make sure the Match Width parameter is
set to the same value you will be using during analysis. Per the note in Section 5.3.1.1, we
recommend a value between 0.4 and 0.75. Lastly, the peak-search sensitivity setting will be the greater of the following: 4 or the value selected on the System tab.
Read From File
This means that the calibration will be read from a
.CLB
file. The later dialogs will ask for the filename for each calibration separately. Each calibration can be from a different
.CLB
file.
When the selections have been made, click Next to go to the next step in the wizard. The next step will depend on the selections made on this first screen.
5.3.8.1. Energy Calibration — Setting Up a New Calibration or Recalling from File
Create New
If you chose to create a new energy calibration, the dialog shown in Fig. 118 opens. Enter the
Library filename and select a Source Label.
When performing this calibration on new data in the MCB, you must enter the live-time preset
(Count Time) in seconds, and mark the Clear Data Before Start check-box. The counting time must be long enough to accumulate well-formed peaks with low counting uncertainty.
To use the spectrum currently in the MCB, unmark the Clear Data Before Start box.
The Source Label entered here is used in a later step that tells you which source to put on the detector.
Click Browse to find the correct library file. To view or change the contents of the library, click
Edit. This opens the GammaVision library editor, which is discussed in Section 5.6.3, page 208.
When finished, click Next.
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