ORTEC Detective X, Руководство пользователя

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ORTEC
®
Detective
®
X Handheld Radioisotope Identifier 1107231N / 082020
12
2.3 MODULAR NEUTRON DETECTOR
The optional Detective X neutron detector is a large-volume segmented lithium-6 fluoride/zinc sulfate
( 6 LiF/ZnS) detector formed in a U-shape that sits behind the HPGe detector so that it does not block the sides
of the detector from absorbing gamma rays . The highest sensitivity to neutrons is in the forward direction,
that is, when the front of the instrument is pointing at the radiation source. Digital pulse processing is applied
separately to each segment, increasing the neutron detection probability while still maintaining a very low
false-positive rate.
The neutron detector module is held in place with magnetic mounts and may be removed and replaced with
the (passive) detector cover to reduce weight when neutron detection is not required. It mates via a
connector (Figure 19) that the Detective X software reads to determine the device type. That information is
added to the N42.42 files, and the software automatically uses the ambient background correction file for
the configuration with the neutron detector. Note that removing or installing the neutron detector may
trigger a neutron alarm; acknowledge it on the touch screen to clear the alarm but note that is not a true
neutron alarm.
2.4 DETECTOR REFERENCE POINTS
For radiation fields from extended sources (e.g., a container full of NORM) or far-field point sources (>1 m
from the instrument), the precise location of the detector the Detective X software uses to determine
exposure rate is not important. When point sources are close to the instrument, the readings from the
different detectors may not agree because they are in different places in the instrument enclosure, and the
dose rate is varying rapidly with position.
If it is desired to test the dose-rate measurement capability with a point source, especially at close range, it
is important to know the reference points of the instrument’s detectors because test procedures, such as
American National Standards Institute (ANSI) or International Electrotechnical Commission (IEC) tests,
prescribe the use of point sources at specified distances from the detector reference point. Figure 20 and
Figure 21 show the detector reference points; note that they are not marked on the enclosure.
NOTE The Detective X is capable of detecting neutron sources even without a dedicated neutron
detector as the system is equipped to detect gamma rays emitted through neutron activation
of common surrounding materials. This is especially true for units configured for an 8 MeV
energy range.