Ludlum Measurements 52-1, Manual

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Model 52-1 Family Technical Manual
Section 4
Ludlum Measurements, Inc. Page 4-4 July 2018
Alarm Time:
adjustable from 1 to 255 seconds. This parameter controls
the duration of the RADIATION ALARM and is indicated by a steady
tone from audio.
Incomplete Time:
adjustable from 1 to 255 seconds. This parameter
controls the duration of INCOMPLETE, which is indicated by a low-
pitched, beeping sound.
RDA Size:
This number, in nCi, indicates the size of the source used
during the automatic RDA calculation. (The Model 52-1 does not utilize
the automatic RDA feature, and the RDA size is set to 500.)
Low Background (BKGND) Alarm:
This parameter sets the number of
counts per 0.2-second interval that the background should not fall below
in normal operation. If background falls below this level, an
INSTRUMENT FAILURE alarm will occur. This alarm indicates if a
detector has failed or is not connected. This alarm will also indicate if the
ambient background has decreased significantly.
High Background (BKGND) Alarm:
This alarm is the opposite of the
LOW BACKGROUND alarm. This alarm will indicate that background
radiation has increased or that a detector has failed.
Sigma:
This parameter sets the number of standard deviations above
background that it takes to set off an alarm. A standard deviation is
assumed to be equal to the square root of the background count. As a
simple example, a 3-sigma alarm of a detector with a background count
rate of 100 counts is calculated as 3.0 times the square root of 100, or 30.
In this simple example, a sudden count of 130 counts would cause an
alarm.
Detector Activity:
This parameter notifies the user whether or not the
detector is active, indicated with a “Y” for “yes” or an “N” for “no.”
Individual Alarms:
An alarm can be set individually for each detector.
This parameter indicates whether one is set and informs the user with a
“Y” for “yes” or an “N” for “no.”
Sum Alarms:
This parameter informs the user whether a sum alarm, a
contribution from multiple detectors, is set, indicated with a “Y” for
“yes” or an “N” for “no.”
# of Samples:
In walk-through mode, this number determines how many
0.2-second samples to group for each alarm calculation.
BKG Update:
This number, adjustable from 1 to 9, adjusts how fast the
background is updated while the portal is unoccupied. The BKG
UPDATE number, multiplied by 18 seconds, gives the response time of
the internal background accumulation.