Nuclear materials detector can pinpoint exact location of radiation sources

WASHINGTON - University of Michigan has created a table-top gamma-ray detector called Polaris, which can not only identify the presence of dangerous nuclear materials, but can pinpoint and show their exact location and type, unlike conventional detectors.

“Other gamma ray detectors can tell you perhaps that nuclear materials are near a building, but with our detector, you can know the materials are in room A, or room B, for example,” said Zhong , an associate professor in the Department of Nuclear Engineering and Radiological Sciences.

Polaris is composed of 18 cubes of the semiconductor cadmium zinc telluride. Each cube measures and records the energy and three-dimensional position of every gamma ray photon interaction that takes place within the detector. It also determines the direction each photon came from.

A computer connected to the detector uses the energy information to identify the type of material emitting it. Different materials appear in the detector’s image as different colors. The device uses the photon direction and position information to show the location of the source.

Polaris will also be more convenient and portable to use in the field, compared with its current counterparts, He said. It operates at room temperature, whereas the high-purity germanium gamma ray detectors typically used today must be cooled to -200 degrees Celsius or they won’t work.

Zhong presented the device this week at the International Workshop on Room-Temperature Semiconductor Detectors, held in conjunction with 2010 IEEE Nuclear Science Symposium and Medical Imaging Conference in Knoxville, Tenn. (ANI)