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Recently, the Department of Homeland Security (DHS) has integrated all nuclear detection research,
development, testing, evaluation, acquisition, and operational support into a single office: the Domestic Nuclear
Detection Office (DNDO). The DNDO has specific requirements set for all commercial off-the-shelf and
government off-the-shelf radiation detection equipment and data acquisition systems. This article would
investigate several recent developments in field deployable gamma radiation detectors that are attempting to meet
the DNDO specifications. Commercially available, transportable, handheld radio isotope identification devices
(RIID) are inadequate for DHS' requirements in terms of sensitivity, resolution, response time, and reach-back
capability. The leading commercial vendor manufacturing handheld gamma spectrometer in the United States is
Thermo Electron Corporation. Thermo Electron's identiFINDERTM, which primarily uses sodium iodide crystals
(3.18 x 2.54cm cylinders) as gamma detectors, has a Full-Width-at-Half-Maximum energy resolution of 7 percent
at 662 keV. Thermo Electron has just recently come up with a reach-back capability patented as
RadReachBackTM that enables emergency personnel to obtain real-time technical analysis of radiation samples
they find in the field1. The current project has the goal to build a prototype handheld gamma spectrometer,
equipped with a digital camera and an embedded cell phone to be used as an RIID with higher sensitivity, better
resolution, and faster response time (able to detect the presence of gamma-emitting radio isotopes within 5
seconds of approach), which will make it useful as a field deployable tool. The handheld equipment continuously
monitors the ambient gamma radiation, and, if it comes across any radiation anomalies with higher than normal
gamma gross counts, it sets an alarm condition. When a substantial alarm level is reached, the system
automatically triggers the saving of relevant spectral data and software-triggers the digital camera to take a
snapshot. The spectral data including in situ analysis and the imagery data will be packaged in a suitable format
and sent to a command post using an imbedded cell phone.
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