Scientists from the Lawrence Livermore National Laboratory in collaboration with engineers at Lawrence Berkeley National Laboratory have developed a mobile, handheld mechanically cooled germanium radiation spectrometer that detects signature gamma-rays from radioactive materials.

Battery operated, weighing only 10 pounds this detector could be used at customs, ports, border crossings and airports.

With precision energy resolution, the spectrometer not only detects the presence of hard X- and gamma- radiation, but also provides information on the quantities as well. The detector is coupled to a low-power electronics package for control and signal processing.

In the past in order to attain the high energy resolution of germanium detectors, the germanium had to be cooled to 90 K in a laboratory setting using liquid nitrogen. However, this new germanium radiation spectrometer is cooled mechanically by a low-power, compact micro cryocooler, eliminating the need for liquid nitrogen, yet attaining the same high-level energy resolution.

Dubbed Cryo3, the spectrometer, which consists of hermetically encapsulated germanium detector, utility vacuum housing, micro cooler, and controller, weighs 10 pounds. The low power requirements mean that Cyro3 can operate up to eight hours on two rechargeable lithium ion batteries.

Cryo3 properties — precision energy resolution, good sensitivity, lightweight, low-power requirements, and mechanical cooling — mean that gamma-ray radiation spectrometers usually restricted to laboratory use can now be used in the field. Cyro3 can operate continuously unattended for at least six months without ever being turned off.

Cryo3 has clear applications for homeland security. Researchers say the device would be able to determine the types of radioactive materials no matter where they might be located — at a border crossing, in an airport, or even on a person.

“Cryo3 provides long-term germanium quality spectroscopy in the field with results comparable to laboratory measurements without the need for a liquid nitrogen supply,” said LLNL physicist John Becker. “Cryo3 couples the high-energy resolution and efficiency of a laboratory sized germanium detector with a low-power, lightweight long-lived micro cooler for the first time, enabling a mobile, handheld package.”

Other applications for Cryo3 include remote area operation, portal monitoring, cargo inspection, unobtrusive operations, and general applications where high-resolution gamma-ray spectroscopy is required and large-volume radiation detectors using liquid nitrogen are not feasible.

Contact: Anne M. Stark, Email: stark8@llnl.gov