ORTEC
®
Detective-EX/DX
®
-100T Portable HPGe Spectrometer — User’s Manual 931040P / 1014
38
Figure 33. Monitor Mode.
Each ID persists until you tap to acknowledge it —
this ensures that no ID goes unnoticed. Once
acknowledged, the ID then persists until the source
that triggered it is no longer being detected.
3.5. SNM Search Mode
The SNM Search Mode screen (Fig. 34) displays bar
graphs showing how closely identifications of
239
Pu,
235
U, and neutron flux approach user-selected detection
thresholds. The thresholds are set on the SNM Search
Mode setup dialog under Advanced Settings (Sec-
tion 5.2.6). Because
133
Ba can be used as a plutonium
surrogate, advanced users can enable a
133
Ba search
for training purposes and for developing a site’s con-
cept of operations. If the
133
Ba search is disabled, its
bar graph is not displayed on the SNM search screen.
SNM searches cannot be saved; to collect data that can be saved and reviewed later, tap
Identify.
Figures 34 through 37 depict a search in which
133
Ba is detected. At the start of the search, the
status message says Continue to search (Fig. 34). This message is displayed until the detection
threshold for any one of the radionuclides or neutrons is crossed. As a
133
Ba source is
approached, the confidence bar associated with it begins to lengthen and approach the threshold
(Fig. 35).
As the Detective-EX comes close to the
133
Ba source, the identification for the radionuclide
exceeds the threshold. The confidence bar enters the shaded part of its box, and the shading
turns red to indicate the radionuclide has been found (Fig. 36). Figure 37 shows a high-prob-
ability hit. To verify the presence of SNM, tap Identify to switch to Identification Mode.
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