Ludlum Measurements 3003, Руководство пользователя

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Model 3003 and 3003i Multi-Detector Survey Meter / SCA
Section 7
Ludlum Measurements, Inc. Page 7-1 September 2020
Advanced Features
Dead Time Correction
All pulse counting detectors have a “dead time” in which the detector is
unable to register another event. In relatively low fields this is not an issue.
However, as the field strength approaches the high end of the detector’s
range, dead time causes the pulse rate to become non-linear with respect to
the real radiation field. Dead time correction is used to linearize the
measurements, allowing a wider linear response range for a given detector.
This instrument uses a second order dead time correction using the equation
𝑟𝑎𝑡𝑒
c
=
rate
m
[1 − (𝐷𝑇𝐶
1
∗ rate
m
) + (𝐷𝑇𝐶
2
∗ rate
m
2 )]
where
𝐷𝑇𝐶
1
and
𝐷𝑇𝐶
2
are the dead time correction coefficients,
rate
m
is
the measured count rate, and
rate
c
is the corrected rate.
Dead time correction coefficients are configured through the device setup
menu or through
Lumic Calibration software. Lumic Calibration software also
includes a wizard that will automate finding and setting the correct
coefficients.
𝐷𝑇𝐶
1
is represented in microseconds (µs) on the device setup menu and in
the software. The equation must be calculated in terms of seconds (s) and
must be scaled appropriately.
𝐷𝑇𝐶
2
has more complex units and are not
shown. However, the representation of the coefficient on the setup menu
and in software do not require scaling.
Note:
Setting the
𝐷𝑇𝐶
2
to zero will disable the second order correction,
while setting
𝐷𝑇𝐶
1
to zero will disable both, regardless of the value
of
𝐷𝑇𝐶
2
.
Section
7