BNC 970 Portable Multi-Channel Analyzer (MCA) - Manual (Page 27)

Model 970 Instruction Manual 24
Efficiency
This displays the Efficiency Calibration Panel. This Efficiency Calibration is based on an ROI
Set, but the same calibration is also used when performing peak-based or library-based
spectrum analyses. An ROI Set, therefore, must be created and/or loaded before this panel is
available. Efficiency Calibrations are unique to specific 970/ROI file/Detector combinations.
Current ROI Set Name: displays the filename of the currently loaded ROI Set. Note: A small
display will appear below Current ROI Set Name: (not shown in the display above) that flags
the fact that the current ROI Set has been altered using the ROI Panel but not yet saved. It is
not recommended that an Efficiency Calibration be performed using an unsaved ROI Set.
If the Allow Edit box is checked, the controls on this panel will be unlocked for editing. If this
box is not checked, the data for the last calibration can be viewed, but not altered.
The arrow buttons will change the currently selected specific ROI within the greater ROI Set
and the data on this panel will reflect only that specific ROI, as will any modifications. The
currently selected ROI will be displayed in fuchsia.
The gray boxes display specific ROI data, including the Efficiency (as a percentage of counts
detected per disintegration), if a calibration has been previously performed.
The Assign ROI as Unknown checkbox allows a specific ROI within an ROI Set to be
designated as one that is not contained in the Efficiency Calibration source being used.
The Associated Nuclide control contains a dropdown list of all enabled nuclides in the current
library. Prior to performing an Efficiency Calibration, a nuclide must be assigned to each
specific ROI within the ROI Set by clicking on one of the items in the list. If the needed
nuclide is not in this list, the library must be edited to enable this nuclide.
The Associated Peak control contains a dropdown list of all enabled peaks (for the nuclide
selected as the associated nuclide) in the current library. Prior to performing an Efficiency
Calibration, one of these peaks must be assigned to each specific ROI within the ROI Set by
clicking on one of the items in the list. If a needed peak or multiplet is not on the list, the
library must be edited to enable or add this peak or multiplet.
Enter the activity of the specific isotope in the Activity input box. This must be performed for
all ROIs within the ROI Set prior to performing an Efficiency Calibration. Use the Units
dropdown list to assign units to the activity. Note: The activity units must be the same for all
activities entered. Changing the units for one specific ROI will change the units assigned to
all other ROIs within the ROI Set.
The ROI Eff. Cal! button performs an Efficiency Calibration by applying the data entered on
the Efficiency Calibration Panel against the currently displayed spectrum. If no data is
contained in the spectrum, or if all the fields are not filled in, errors will be generated and the
Efficiency Calibration will be aborted.