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If “Alarm at:” is checked, the analog display will turn red and an audible indicator will be played if the count
rate exceeds the value contained in the input box. The alarm will reset when the count rate falls below the
alarm level, or when the box is unchecked.
“Meter Response Time” changes the number of seconds of data over which the analog display is averaged.
Higher values will result in a “smoother” meter action, but slower response to changes in the count rate. This
can be varied between 1 and 60 seconds.
If “Autorange” is checked, the meter scale will change automatically based on the count rate.
The “Scale Max” changes the base value for the upper limit of the analog display.
The “x 1” through “x 10,000” are scale ranges for the analog display.
“Ratemeter units” allows you to change the analog display between units of counts per minute (cpm) or counts
per
Procedures
Calibrating a Detector with URSA-II
In order to use URSA-II with a given detector, the following must be done (in this order):
1. Adjust Hardware Settings.
2. Perform Energy Calibration.
3. Perform a Shape Calibration. Following this step, URSA-II is ready to provide qualitative analysis.
4. Create a “Regions of Interest” (ROI) Set. This is in preparation for efficiency calibration, which must be
coupled to an ROI set.
5. Perform Efficiency Calibration. Once an efficiency calibration has been performed, URSA-II is ready to
perform quantitative analysis.
Adjust Hardware Settings
Hardware settings are used to adjust input and polarity, high voltage (HV), threshold, gain, fine gain, and
shaping time.
Hardware settings are unique to each URSA-II /detector combination. The specific settings are loaded when
a specific detector is selected. If you intend to use the same detector at different hardware settings, you can
define separate detectors with different descriptions.
Since URSA-II was designed to work with essentially any radiation detector (or more specifically, in the case
of URSA-II MCA, essentially any gamma detector), the software cannot make any assumptions regarding the
operating characteristics of the detector and therefore cannot contain automated hardware adjustment.
Discovering the appropriate hardware settings for a particular detector is essentially a trial-and-error process.
