GammaVision
®
v7 (A66-BW) 783620H / 1013
6.10.4.1. PBC Match Width (By Energy option OFF)
The PBC is applied only if the nuclide name is the same as the nuclide defined in the PBC file
and the two peak energies are within the Match Width specified on the Correction tab. The default PBC match width is 0.2 times the peak FWHM. For backward compatibility with earlier versions of GammaVision, if the match width is found to be zero, the default match width is used. The minimum match width is 0.1. If you specify a non-zero Match Width, it is used as follows.
For each peak at energy E
0
, the PBC match width in keV is calculated first:
(85)
where FWHM is the calibrated peak FWHM at that energy and f is the Match Width value specified on the Correction tab. Then the energy range from E
1
to E
2
is considered for PBC matching width:
(86)
A PBC peak is considered a matching peak if the PBC peak energy is within this energy range.
The PBC uncertainty calculation is discussed in Section 6.12.12.
6.10.4.2. Match by Energy Only (By Energy option ON)
If the by Energy checkbox is enabled on the Correction tab, when a PBC file is generated, all peaks with uncertainty less than the Peak Cutoff will be added to the PBC file — this includes all identified library peaks and all unknown peaks. The unknown peaks are saved as belonging to a null nuclide name, Un-0.
Analysis of this case proceeds as follows: At first, PBC peaks are associated with the closest spectral peak. The absolute centroid energy separation between the PBC peak and spectral peak is used for this purpose. For example, assume a PBC peak has an energy of 186.00 keV. If there are peaks at 185.70 keV and 186.20 keV, the 186.00 keV PBC peak is considered to be associated with the 186.20 keV peak (energy difference 0.2 keV) rather than the 185.70 keV peak
(energy difference 0.3 keV).
Next, the PBC Match Width is applied to see if the energy separation between the subject peak and the associated PBC peak(s) is within the acceptable PBC match width. If within the match width, PBC is applied to the peak. Otherwise, PBC is not applied.
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