Scouting Hidden Danger:CBRN Detectors on the Frontline of Public Safety Ⅰ

Radiological detectors often fall into two categories: personal-radiation detectors (PRDs) and radioactiveisotope identification devices (RIIDs). “PRDs are used for personal protection as well as basic search capabilities,” said Lester Koga, PM at Morpho Detection. “RIIDs are used for identifying the radioactive isotope to determine the threat level of the source — special nuclear material, medical, industrial or naturally occurring radioactive material.”

To determine if a detected radiation is from a radiotherapy patient or from special nuclear material, accuracy is paramount. “Generally the lower the energy resolution percentage, the more accurate the isotope reading will be, creating fewer false-positive and false-negative readings,” Koga said.

With less than 1 percent energy resolution high-purity germanium (HPGe) is the gold standard material to use, yet it is inoperable at room temperature and needs to be cryogenically cooled. This limits the size, weight and battery life of such detection devices, Koga explained.

New detection materials such as cadmium zinc telluride (CZT) can be used for lighter and more portable devices, without sacrificing accuracy in radiation detection. “With less than 2 percent energy resolution, CZT enables increased probability of detecting and correctly identifying a radioactive isotope when compared to sodium iodide, in a package much more user-centric than HPGe,” Koga said. A barrier to CZT adoption is its higher cost, compared to inexpensive and ubiquitous sodium iodide.

First Line of Defense
Often the basic sensors used in handheld, mobile and stationary detectors are the same, although technologies employed are sometimes simply too large or powerintensive to be considered for portable applications. Significant R&D efforts have been devoted to achieving the goal of creating lighter, longer-lasting portable instruments, and in general instruments, portable and stationary, that simply bring greater capability to CBRN detection. The main differentiators are the user and the purpose the user wishes to achieve by using the device. “CBRN specialists, law enforcement personnel and first responders might all have different missions and purposes when using the detectors, and each situation requires the use of specific equipment for maximum effect,” said Craig Johnson, CEO of Field Forensics.

Depending on what the user is trying to accomplish and what the mission entails, handheld, mobile and stationary detectors are all utilized frequently. The wider the range covered by the instrument, the more costly it would be, Rothbacher said. In terms of software preinstalled in the instrument, minor adjustments and troubleshooting can be completed. In some other instruments, changes cannot be made to the software at all. As of now, third-party instruments and embedded software are not interoperable.

Handheld devices are limited in size, weight and power consumption, while mobile and stationary systems are less affected by these factors for design and optimum performance capability, Anttalainen said. Ease of use and maintenance requirements are also performance differentiators to consider. It should be noted that mobile detectors can be used in a stationary manner, becoming a satellite detection point within a large detection network controlled by a central command center. With sufficient battery power, mobile detectors can last longer than usual when used as a stationary device.

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