931040P / 1014 8. USING THE DETECTIVE-EX WITH ORTEC SPECTRUM ANALYSIS PROGRAMS
89
Figure 93. Detective-EX Presets Tab.
To resolve status problems, refer to the troubleshooting list in Chapter 7. For further assistance,
contact your ORTEC representative or our Global Service Center.
8.3.9. Presets
Figure 93 shows the Presets tab. The
presets can only be set when the
Detective-EX is not acquiring data
(during acquisition the preset field
backgrounds are gray indicating that
they are inactive). You can use any
or all of the presets at one time. To
disable a preset, enter a value of zero.
If you disable all of the presets, data
acquisition will continue until man-
ually stopped.
NOTE The presets on this tab do not
affect the Detective-EX when
the instrument is operating in
standalone configuration
(disconnected from the computer). When operating as a standalone identifier all presets
are cleared. When the Identify button is pressed, the Detective-EX will always
continue to take data until the Stop button is pressed.
When more than one preset is enabled (set to a non-zero value), the first condition met during
the acquisition causes the MCB to stop. This can be useful when you are analyzing samples of
widely varying activity and do not know the general activity before counting. For example, the
Live Time preset can be set so that sufficient counts can be obtained for proper calculation of
the activity in the sample with the least activity. But if the sample contains a large amount of this
or another nuclide, the dead time could be high, resulting in a long counting time for the sample.
If you set the ROI Peak preset in addition to the Live Time preset, the low-level samples will
be counted to the desired fixed live time while the very active samples will be counted for the
ROI peak count. In this circumstance, the ROI Peak preset can be viewed as a “safety valve.”
The values of all presets for the currently selected MCB are shown on the Status Sidebar. These
values do not change as new values are entered on the Presets tab; the changes take place only
when you Close the Properties dialog.
Enter the Real Time and Live Time presets in units of seconds and fractions of a second. These
values are stored internally with a resolution of 20 milliseconds (ms) since the MCB clock
increments by 20 ms. Real time means elapsed time or clock time. Live time refers to the amount
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