5. Click <Calculate Efficiency>. A window will be displayed telling you to prepare to count
Background. Ensure there are no isotopes in the area before you click <OK>.
6. Once you click on <OK>, the system will proceed to count for 100 seconds. When it is done
counting, a menu will be displayed telling you to place an isotope at the proper distance from the
detector and to click <OK> when ready. When you click <OK> this time, the system will again start
counting for the isotope for a 100 second time frame. When the system has finished counting for 100
seconds, calculated detector efficiency for this isotope will be displayed starting with the activity
that you have entered.
Decayed Activity
To determine the decayed activity of a source: (For example, the current activity of a sealed Co-57 source.)
1. Open the Detector Efficiency page.
2. Select the desired isotope by clicking on the <down arrow> and selecting the desired isotope.
3. In the Assay window, click on either <Bq> or <µCi>.
4. Enter the calibration time and date for the source.
5. Enter the activity at the time of calibration.
6. In the window at the bottom of the screen you’ll see listed “Today’s Activity at the current time
is _______.”
SPECTRUM ANALYSIS
(See Figures 3-12 and 3-13.)
Spectrum Analysis is available in any operational mode throughout the program. This option allows the
user to change the ROI on the display, add additional ROI's, or print the spectrum with counting
information.
To Access The Spectrum Analysis
1. Click on <Spectrum> in the primary tool bar. The Spectrum Analysis screen should now be displayed.
The spectrum from the immediately preceding count is shown with its associated data. On the
Spectrum Analysis screen, the ROI for the isotope counted is shown on the screen. The set window
for that isotope is displayed in the bottom of the Cursor Window. The left channel is shown in the
Select Left Cursor box while the right channel is shown under the Select Right Cursor box. The Select
Data Cursor is your cursor that can be moved.
2. To move any ROI or cursor, click on the box for the appropriate line and then use the <Up> or
<Down> arrows under the cursor. As you move the cursor, the energy and counts associated with
that channel will change.
• On the right hand side of the screen, the cursor window shows the energy between lower and
higher keVs set by the ROI shown to the left.
• The counts are the counts in that region of interest. The count rate is the rate in the region of
interest that the cursor is in, displayed in cpm.
• The full width half max (FWHM) is displayed for the appropriate peak in that window.
CONTENTS
ADMINISTRATION 3-20
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