neal@lynx.uucp (Neal Woodall) (04/26/89)
I have recently decided to purchase a geiger counter, for general use and for possible survival applications. I have seen several different types of devices offered for sale, including some that are old US Civil Defense surplus, some that are based on solid-state sensors that are obviously commercial-grade units, and some that are advertised as being European/NATO surplus (brand new, never opened). Now for questions/confusion: I believe that the geiger counters that I have seen can be broadly classed "radiological health" units (measure in the .5 to 500 milli-roentegen/hour range and are not "hardened" or weather-proof) and those that are intended for military/war conditions (measure in the 1-500 roentgen/hour range and are "hardened" and weather/water proof). How exactly is a "roentgen" defined? Is it in terms of energy dose, or just in terms of "counts" (ie, gamma striks regardless of energy, also do beta/alpha strikes count, even though they are obviously not as bad as high-energy gammas)? What is considered normal "background radiation" in roentgens? Also, do any of these detectors count neutrons (which are very bad)? Is a geiger tube detector better than solid-state (or vise versa) and under which conditions/uses is either "better" than the other? How is a roentgen (one measure of radiation) related to a REM (which I believe stands for Radiation Effective to Man)? What dose of roentgens/REMs in bad/worse/fatal? (I have been told that more than 350 roentgens is bad/fatal) As you can tell, I have lost of questions that perhaps one of you can answer for me. I have used a solid-state commercial-grade unit (belongs to a friend) and it was quite interesting to use. One of the "funniest" things occured when we tested another friend's rock/mineral collection....we found that two of his rocks (uranannite and cuprosklodouskite (both probably spelled wrong)) gave off MUCH more radiation than the normal background. This device measured the radiation in "counts" or "events" (which I understand to be the detection of an alpha/beta/gamma of greater than some threashold energy). Normal background was about 12 counts/minute....these rocks were on the order of 7000 counts/minute! The rocks now reside in a metal box in the garage. My friend's wife went through a nite of severe depression when she was just sure that they would never have kids! She has completely forgotten the whole episode now. Anyway, all practical answers/info is appreciated. I undertand the difference between alphas (ionized helium nuclei), betas (high energy electrons) and gammas (very high energy photons) and why fast neutrons are so VERY bad (affect the nucleus of an atom, rather than just the electron shell). Any info concerning the "practical" aspects of radioactivity, radiologcal health, geiger counters, etc. will be appreciated. All follow-ups have been directed to sci.electronics. Thanx in advance! Neal