GammaVision
®
v7 (A66-BW) 783620H / 1013
6.3.8. Narrow Peaks
The peak width is compared to the calibration width at the half and tenth maximum. If the peak is too wide or too narrow it is marked to show this in the output report. If the peak is too narrow, it is not used in the abundance calculation unless the “accept-low-peaks” or “accept-all-peaks” switch (T=accept low peaks, page 444) is turned on. If accept-all-peaks is on, all are accepted. If accept-low-peaks is on, the peak is further tested. If the peak area is less than 200 counts, it is accepted. If the peak area is between 200 and 300 counts and the background is less than half the peak area, the peak is accepted. If the peak area is over 300 it is rejected.
6.4. Suspected Nuclides
The suspected nuclides feature will identify peak energies in the unknown peak list, based on a second gamma-ray library. The unknown peak list is the list of all peaks located in the spectrum that are not in the analysis library. It is intended to help identify unexpected peaks or can be used to note peaks that are always present but for which no analysis is desired (e.g.,
40
K or 511 keV).
The name for the suspected nuclide library is specified on the System tab under Analyze/
Settings/Sample Type....
For each energy listed in the unknown peak list, the nuclide with the closest energy within four times the FWHM is listed. In the event that two energies are found with the same difference, the lowest energy entry in the library is printed. If none is found, a symbol is printed. In addition, the same symbol is printed if the suspected library is not found, a read error occurs, or the spectrum is not calibrated.
The suspected nuclide feature can be used with calibrated spectrum files (and no analysis library) to obtain a quick list of nuclides in the sample and their peak count rates.
6.5. Locating Multiplets
A peak is considered to overlap if its start or end channels are within another peak region. The peak overlap range factor in b30winds.ini
(in units of peak FWHM; see page 248, 449) determines whether two peaks close in energy will be deconvoluted as a multiplet or stripped. The lowest setting for this parameter is 1.0; the default value is 3.5. If you change its b30winds.ini
entry to less than 1.0, the analysis uses a value of 1.0.
If the library energies are less than 10 eV apart, only the lowest energy peak is included in the deconvolution. The peak areas for the other peaks (within 10 eV) are set to zero. The conflicting peaks are marked as energy-conflicting peaks. This message appears on the report and the individual peaks are labeled in the comment field of the nuclide/peak matrix. See the discussion of library-based peak stripping, Section 6.5.5.
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