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Radiation Detection Goes Digital
RedEaredSlider writes "In science fiction, explorers wave around a single device and pick up many kinds of radiation — think of the tricorders on Star Trek or Dr. Who's sonic screwdriver. A professor at Oregon State University is bringing that a bit closer to reality, though in this case it's for finding radioactive material. 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."
Geiger counters are used to detect radiation (usually gamma and beta radiation, but some models can also detect alpha radiation).
Geiger-mueller counters respond to the commonly encountered types of radiation, namely, alpha and beta particles as well as gamma and x-radiation. However, GM counters cannot determine the type, energy, or vectors of the detected radiation.
They are generally much larger than this device and provide little in the way of discrimination by type.
Sig Battery depleted. Reverting to safe mode.
Perhaps it is because a beta radiation detector is useless if it is in your pocket.
Beta radiation detectors in general don't have a lot of use in the field because there is always gamma radiation with beta radiation. And small gamma detectors already exist, such as the digital electronic portable dosimeters workers at nuclear plants use. If there is a question about beta dose, these same workers have thermoluminescent dosimeters with beta windows that can be analyzed on-site. If you actually need to survey an area, you can always use a beta-gamma dosimeter, but you would only do that if you were health physics tech.
There is no real use for this device.
As a physicist that works with radionuclides, I'm appalled at this article. It is horribly written. "The crystal vibrates in a certain way" made me laugh.
A better summary is provided by OSU public relations dept at
http://oregonstate.edu/ua/ncs/archives/2010/dec/new-technology-speed-cleanup-nuclear-contaminated-sites-reduce-costs-and-create-jo
Radiation detectors have been digital for a long long time. Some of the electronics has been analog because analog electronics are faster and always will be for filtering and integration.
Beta particles (electrons ejected from the nucleus, basically) have a mean free path of about a foot in air. Place anything else in between, like a thin sheet of aluminum or a little bit of plastic, and it sucks up the betas real quick.
The other big problem is that gammas are quantized, beta particles are not. When something radioactively decays, it gives off gamma rays of distinct, unique energies -- very useful for determining the radioactive isotope you're looking at. Not so for betas; they're emitted over a wide range of energies, and it can be very difficult (but not impossible) to tell what you're looking at by betas alone. I don't mean to downplay what this accomplishes, in a nice, small form factor. But this doesn't revolutionize the world of radiation detection. To date, no one has really been crying for a combined, digital, gamma and beta detector. Maybe if you build it, they will come, but I don't see a large market for this.
"Diplomacy is something you do until you find a rock." --Richard Pound
More importantly, what episode(s) did Dr. Who use the sonic screwdriver to detect radiation?
I don't remember any...
love is just extroverted narcissism
The (now grand)parent should be modded up, but one thing in your post is just plain wrong: the range of beta radiation is not "about a foot"; the range of beta radiation depends on its energy. Betas from a low energy nuclide like 35S, for example, do have a range of almost exactly a foot (32 cm) in air, but the high energy beta radiation emitted by 90Sr/90Yr OTOH has a range of slightly above 10 meters in air. And as for the quantization, beta emitters too have very distinct energy distributions (which you can look up in any good data sheet).
But you're right about portable beta spectrometry being pretty "meh". If it's high enough energy to worry about, it's easier to just look at the bremsstrahlung, really.
BTW, this was a really horrible article. There were no technical details whatsoever (well, just enough to realize that someone had been trying to explain scintillation to the very obviously non-techie journalist), and they seem to mix up radiation spectrometry with plain radiation detection...
Their claim is that the beta/gamma ratio (which it detects) is useful. Are you saying it is not?
If all it does is detect the ratio then it is close to useless. Suppose there are three elements A (gamma only), B (beta only) and C (gamma+beta). If all I can do is detect the ratio of betas to gammas then it is impossible to distinguish between material that is 100% C vs. material which is 50% A and 50% B.
Fortunately nature provides a solution and if you measure the energy spectra of gamma rays it will very quickly tell you which elements are present. So, as described in the article, the device seems useless for its intended purpose. However the article is very badly written so I'd reserve judgement until proper information is available.