LLNL, LBNL collaboration produces improved method for detecting radiation
Five years ago, physicist John Becker thought he’d change career
directions.
But instead he had a conversation with some colleagues at Lawrence Berkeley
National Laboratory and they started work on something they knew could
fine-tune the science of detecting radiation.
The next thing they knew, they had designed and built a mobile, handheld
mechanically cooled germanium radiation spectrometer.
The spectrometer not only finds the presence of hard X- and gamma radiation,
but also provides information on the species 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 maintaining the same precision energy
resolution of germanium.
Dubbed Cryo3, the spectrometer, which consists of a hermetically encapsulated
germanium detector, utility vacuum housing, micro cooler, and controller,
weighs 10 pounds. Cyro3 can operate up to eight hours on two rechargeable
lithium ion batteries because of its low power requirements.
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 and counter terrorism.
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," Becker said."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, shipboard
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.
"Cryo3 offers extremely high-resolution radiation analysis in a portable
package," said Lawrence Berkeley engineer Lorenzo Fabris.
The development team consists of John Becker of Livermore and Christopher
Cork, Lorenzo Fabris, and Norman Madden of Berkeley. The four-year long
development project is funded in part by the U.S. Department of Energy’s
Office of Nonproliferation Research and Engineering within the Office
of Defense Nuclear Nonproliferation.