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Physics Faculty Awarded Patent for Radiation Detection Device
U.S. Navy photo by MC2 Michael Ehrlich

Physics Faculty Awarded Patent for Radiation Detection Device

By MC2 Michael Ehrlich

NPS Department of Physics Distinguished Professor Gamani Karunasiri and Dr. Fabio Alves, a retired colonel in the Brazilian Air Force, have recently been awarded a patent for their discovery of a "Solid-State Spark Chamber for Detection of Radiation." The device has drawn great interest because of its efficiency in cost, energy consumption, and most notably, its size.

"Spark chambers are very well known, but they usually require huge amounts of gas, and high voltage to operate," said Alves. "This detector is much smaller in size and extremely low cost, and you can monitor very large areas if you have several of them distributed."

The applications for such devices primarily revolve around the detection of varied types of radiation, such as tracking nuclear vessels or weapons, or detecting radiation leaks. Karunasiri describes how a spark chamber device detects radiation with an analogy.

"Imagine a huge stone on the edge of this table. It's unstable as it sits there, and you only need a tiny force for it to fall," he explained. "Once it falls, we see that, but we don't see the particle that came and moved it. The idea here is the same, we keep a semi-conductor device at certain voltage almost ready to spark, but not quite. It needs a little something to initiate and that is the radiation. It produces a pulse as a signal that we can see on a scope."

The researchers' invention did not just miniaturize existing technology. Rather, it's a new approach to the use of existing technologies in a new way, resulting in a new device.

"The idea for this came from these old detectors, which normally require a large volume to use gases that have very low density," explained Karunasiri. "So when the ionizing radiation, like nuclear, alpha, beta or gamma particles, interact with the low density of the air, you normally need a large volume of air to detect. The idea we had was, can we use a smaller size? Solid state means very dense, so you can reduce the volume to detect this radiation. It's a completely different technology."

The patent was awarded to Karunasiri and Alves on March 14, but this was not the first project they worked on together.

"I was an NPS student in 2003 and retired from the Brazilian Air Force in 2009. [Karunasiri] supervised me in my Ph.D.," said Alves. "Later in 2010, I came here as a postdoctoral researcher. Now, I work as a contractor for a company providing research support to the physics department."

Alves compares his experience as a student to being a researcher at the school he once attended.

"As a student, NPS is unique in the network you are able to create. Your entire cohort is in the defense realm, they are officers in the military," said Alves. "With the exchange of ideas and problems you discuss, you leave here realizing that you had the opportunity to bring these ideas to the faculty, and ask for help in solving these problems for the defense community.

"As a faculty or researcher, you now have these unique students with defense or military minds, and they can provide an evaluation of your research to see how it can be used for different applications in the operational field," he continued.

Ultimately, Karunasiri said, the dynamic between innovative scientists and operationally-experienced students creates inventions with definitive applications.

"What we like about NPS is that, while we still focus on applied research in physics, the students' field experience immediately provides new ideas, coming up with many applications for the new tool," Karunasiri said. "We produce something and we can use it for real-world applications.

"Now we are working on sound checks that can detect the direction of sound," he added. "People are becoming really interested."

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Today@NPS showcases some of the speakers, conferences, experiments, lectures, and other events that take place at the Naval Postgraduate School on a daily basis. If you would like more information about any of the highlighted activities please contact the public affairs office at pao@nps.edu.

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April 2017

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