NukeWorker Forum
Reference, Questions and Help => Nuke Q&A => Lessons Learned => Topic started by: jdald on Apr 26, 2004, 01:11
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I am looking for a reliable Ion Chamber meter for dose rate surveys of leakage on Electron microscopes, analytical units, and Machines that electronically produce Xrays at energies of 10 kev and higher. Right now I am using an ASP-2 with a PG-2 probe that cannot be calibrated to read out in microrem or millirem, and the conversion from cpm to any of the two is not reliable.
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There are many options and if you need to get down to the 10 Kev range you need something similar to that of a fiddler used to detect that 47 or so Kev photon from Am-241.
Many will use a regular NaI(Tl) in the 1" X 1" or 2" x 2" crystal configuration.
The key is to ensure that what ever device you are looking for should cover the entire photon energy spectrum that you anticipate or as mandated by technical specifications.
Contact prospective manufacturers to better understand your options.
Have a great week!
Moke ;D
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I now know why you are looking here for the answer. Many of the manufacturers site's are not set up to be very friendly to potential customers who wish technically specific information. I received an answer from Ludlum who recommended the following of their own instrumentation.
http://www.ludlums.com/product/m3.htm - Model 3
http://www.ludlums.com/product/m14c.htm - Model 14C
http://www.ludlums.com/product/m2241.htm - Model 2241
http://www.ludlums.com/product/m44-7.htm - Model 44-7
http://www.ludlums.com/product/m44-9.htm - Model 44-9
http://www.ludlums.com/product/m44-3.htm - Model 44-3
I hope this helps in your search.
Personally, the only one of these probes that I have experience with in a LEG manner is the 44-3. It works quite well and is fairly rugged. The latter characteristic is most important when I have physical non-control of delicate instrumentation.
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reliable ion chamber fer low gammies 'n xrays? man, i hate it when a question like this getz inta my head.... it jist keeps rattlin around in there until something triggers a response..... yer basic cascade cranium.
going thru the latest 'n greatest frum cardinal health today, 'n here's what they got that hits the criteria asked:
victoreen model 470a panoramic survey meter
unsealed ion chamber
gamma >8 MeV
beat >120 keV
gamma/xray >10keV
<1kr/hr
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man, i hate it when a question like this getz inta my head.... it jist keeps rattlin around in there until something triggers a response..... yer basic cascade cranium.
Man, I hope your group health plan covers therapy! +Karma for your perspective, which continues to amaze (and frighten) me!
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Wait a minute! Your checking for leakage from an electron microscope, 10 Kev to ?, and you've been using an instrument that you pressume to be completely unreliable and unproven, for the purpose you are using it?
The manufacture should be able to give you a valid spread of the spectrum of X-ray, low to high. Stick to a scintilation detector and forget about the ion chamber! Looks like a good NRRPT question!
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We use a low energy Bicron Micro Rem meter. It has a window allowing detection from ~10 to 1400 keV.
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I suggest going to http://www.radcal.com They specialize in x-ray survey instruments. An old type unit was the 1015C which was well suited for diagnostic energy x-rays. I can help you with selection of instruments if needed.
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We ALSO (metalman40) use a low energy photon Bicron Micro Rem meter (the BLACK BOX). It has a plastic scintillator detector which is tissue equivalent (no conversions needed). We use it to check operations of X-Ray package inspection equipment and for most low radiation shipping. Very sensitive to low energy photon radiation (X-RAYS) with a small mylar end window for more accurate detection of leakage, much better than ion chamber based instrumentation. Reads directly in micro rem/hr.
Excellent for checking background radiation conditions. Durable and less problems than air/vented ion chamber based dose rate instruments.
COMPLETE DOCUMENTATION is at work, I'm quoting from memory and we have a LOT of instrumentation - - - - - laugh!