BNC 970 Portable Multi-Channel Analyzer (MCA) - Manual (Page 28)

Model 970 Instruction Manual 25
The Cancel button will make any alterations made on the Efficiency Calibration Panel revert
back to the ones used in the most recent Efficiency Calibration.
Every time an Efficiency Calibration is performed, a report is generated and stored in the 970
Cal Files directory. This report can be viewed, printed, or saved by clicking the Report…
button. Note: The contents of the report and use of the report window are discussed in detail
in other portions of this manual.
Peak-Based
This displays the Peak-Based Panel for performing peak searches, and for performing
isotopic identification and peak-based Quantitative Analysis.
Clicking the Find Peaks button causes SNAP-MCA to search the currently displayed
spectrum for identifiable peaks. These will be displayed on the spectrum in green, with a line
indicating the peak centroid. The collection of found peaks acts a bit like a temporary ROI
Set, and the currently selected peak (which will be the leftmost one immediately following a
peak search) will be displayed in fuchsia.
Clicking the Report… button makes SNAP-MCA perform a Qualitative Analysis. If an
Efficiency Calibration has been performed, a Quantitative Analysis will also be preformed.
This will then be displayed on a “report” screen, where it can be viewed, printed, or saved.
Note: The contents of this report and use of the report screen are discussed in detail in other
portions of this manual.
The Clear Peaks button will erase all found peaks. The Make ROI button allows the user to
take a group of found peaks and convert them to an ROI Set.
The Peak Search Sensitivity control affects how “distinct” a peak needs to be before it is
flagged as “found.” If it appears that too many peaks have been identified in a peak search,
try lowering the value of Peak Search Sensitivity. Conversely, if too few peaks have been
identified, raise the value of Peak Search Sensitivity.
Placing a dot associated with one of the four radio buttons will determine which method is
used in identifying the nuclide associated with a peak. The top item will associate a peak with
a nuclide if the library energy is within the stated energy range of the peak’s centroid. The
next item, if selected, will associate a peak with a nuclide if the library energy is within the
stated percentage of the library energy. The third item, if selected, will associate a peak with
a nuclide if the library energy is anywhere within the area of the found peak. The fourth item,
if selected, will associate a peak with a nuclide if the library energy is anywhere within the
FWHM (full width at half maximum) calculated for the found peak.
There has been no computer program ever written that surpasses an experienced human
eye at discriminating whether a given portion of a spectrum represents a peak or not.
Therefore, SNAP-MCA allows the user wide latitude in editing (or ignoring) the results of the
computerized peak search.