Radiation+Devices

There are several common portable radiation detectors available today.

A diagram of a typical Geiger counter http://www.nuc.berkeley.edu/news/Sci_teachers_workshop/teachers_workshop/geiger_counter.gif


 * Geiger Counter**: The Geiger counter, the most commonly used handheld radiation detection device, was invented in 1908 by Hans Geiger, for whom it is aptly named. A Geiger counter is a metal tube with a metal wire along its middle, and is filled with an inert gas, usually helium, neon or argon. When about 400-600 volts are applied to the gas inside the tube via the connected power source, it will emit electrical pulses if radiation bombards the tube. These pulses are converted to readouts on the meter, measured in some form of roetgens or rem per hour (i.e. milliroetgens per hour or millirem per hour). If the Geiger counter in question possesses a speaker, it will also give an “audible click” when radiation is detected. Depending on the type of Geiger counter, it can detect alpha, beta, or gamma radiation. The types it can detect depends on the thickness of the end window on the tube. Since Gamma waves are very high energy, the thickness is not important and all tubes can detect Gamma radiation. To detect Alpha radiation as well, the end window thickness must not be more than, otherwise it will not be efficient enough to rely on for an accurate readout. Beta radiation is the most difficult to detect – the counter must have an end window thickness of approximately , and the thickness of the metal tube should not be over . A Geiger counter can be used in a laboratory, but is also useful for military scouting of areas filled with pockets of radiation.

A diagram of a Micro-R meter http://www.nukeworker.com/pictures/displayimage-442-27.html


 * Micro-R Meter**: A Micro-R meter looks remarkably similar to a Geiger counter, and displays readouts in the same fashion (microroetgens per hour). However, A Micro-R meter’s method of detection, rather than electrified gas, is a solid crystal of sodium iodide which creates a pulse of light when bombarded by radiation. This pulse is converted to a readout via a photomultiplier tube, which takes the amount of light and energy in the crystal and (very, very accurately) estimates the amount of radiation that hit it. A Micro-R meter is useful and possess a speaker to deliver a “click,”, but is not as common as a Geiger counter, due to the fact that it can only detect Gamma radiation. It possesses the same basic uses as a Geiger counter.


 * Portable Multichannel Analyzer:** This is simply a Micro-R meter with the addition of a multichannel analyzer electronics package, which gives it the ability to display the types of radioactive materials being detected. This version of the meter is also incredibly useful for the military, as it is used to identify unknown sources of radiation. However, it can still only detect gamma radiation.

The external view of an electret ion detector. The Teflon disc is contained inside. http://www.rtca.com/images/eid.jpg


 * Electret ion detector:** An electret ion detector is a passive radiation detection device, which means it is not powered by electricity. The detector consists of a statically charged Teflon disc, which is placed in the pocket of radiation. When the alpha particles that are formed from radioactive decay strike the disc, the charge is reduced. A multichannel analyzer is then used to measure reduced charge. This detector can only detect alpha radiation, and is frequently used as a radon detector in common homes.

BIBLIOGRAPHY

"FAQs and Application Notes." Alrad Electronics. Alrad Electronics. 30 Jan 2008 <[|http://www.alrad.co.uk/electronics/FAQ-GeigerCounters.htm>.]

"How Can You Detect Radiation?." Health Physics Society. 21 Sep 2007. Health Physics Society. 30 Jan 2008 <[|http://www.hps.org/publicinformation/ate/faqs/radiationdetection.html>.]