Radiation Detection Goes Digital

It's a radiation spectrometer, and it works on a very old principle: particles and photons that hit certain materials will make them emit flashes of light. But for decades, radiation spectrometers had been limited to detecting only one kind of radiation at a time. David Hamby, an OSU professor of health physics, felt that there was a need for a device that could see at least two kinds of radiation, as well as be smaller than the models currently available.

To do that, Hamby turned to sophisticated digital signal processing. Current detectors on the market tend to use analog systems, which is one reason they can't see more than one type of radioactivity. Over the course of 10 years, he worked with Abi Farsoni, an assistant professor in the College of Engineering, and came up with the device he has now.

Radiation detectors have not moved into the digital world, he said. And it was really the only way to make this device work. In the analog world it wouldn't function.

The detector is simple in principle: a detector has in it a crystalline material. That crystalline substance gets hit by an electron (also known as a beta particle), gamma radiation or even x-rays. The crystal vibrates in a certain way and emits a tiny flash of light. By analyzing the signal one can see exactly what kind of radiation is being produced.

Each kind of radioactive material produces different ratios of gamma rays to beta particles, and so from the signal one can tell what it is. A basic use for the detector is to see whether a soil sample, for example, is contaminated with anything radioactive. It could also be used to check whether a given area is worth mining for elements such as uranium.

Hamby notes that a big plus is that the kinds of radioactive material that is most dangerous to people -- elements such as strontium, cesium and yttrium -- are the ones that tend to emit the most beta particles. Another useful aspect of the instrument is that it saves time. Previously, finding radio nuclides was time consuming, since a different detector was needed for each one.

The OSU College of Engineering has contracted with Ludlum Instruments, a Sweetwater, Texas, manufacturer, to produce the first instruments, and the OSU Office of Technology Transfer is seeking a licensee for commercial development. The electronic systems for the spectrometers will be produced in Oregon by Avicenna Instruments, the company formed to develop the technology.