Ludlum Measurements 2241-2, Руководство пользователя

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Model 2241-2RK Technical Manual
Section 8
Ludlum Measurements, Inc. Page 8-12 July 2012
D
ETERMINING
CC
AND
DTC
This procedure contains the algorithm ( hi-lo method) for determining the CC
(Calibration Constant) and the DTC (Dead Time Correction). An example
of the Ludlum Model 44-9 GM detector calibration is used in conjunction
with the algorithm calculations to aid in solving the equations.
Note:
Ludlum Measurements, Inc. offers a PC-compatible software
program that incorporates the read/write commands necessary
to communicate between a PC and the Model 2241-2.
The program also incorporates the algorithm to calculate the
detector CC and DTC. The software is offered in a DOS
version (part number 1370-025) or a WINDOWS version
(part number 1370-024).
Hi-Lo Method
The following summary lists the calibration constraints.
: The hi-lo method refers to the placement of the detector in a
radiation field using a two-point (CC and DT) calibration to make linear the
detector response, even in the non-linear operating regions of the detector.
The low radiation field (CC) should be a field that yields from 2 to 5% count
loss. The high radiation field (DT) should be a field that yields from 30 to
60% count loss. The algorithm ignores background counts, and therefore,
the low field must be at least 10 times the background count.
Calibration and Dead Time Calibration Constraints
FIELD CONSTRAINT
BACKGROUND *10 times less than low field
LOW FIELD Yields from 2 to 5% count loss
HIGH FIELD Yields from 30 to 60% count loss
* This constraint only applies when using two sources (two fields) or a
radiation range calibrated without background consideration.