Quote: Originally posted by gammainspector |
Based on what you want to use it for, I would be less interested in a ratemeter if I were you and more interested in some kind of counter/scaler. A
good example of the differences is the Ludlum Model 2221 and the Eberline E600. The Ludlum unit is a versatile unit that can do just about anything
you want to do in the field, but is more focused on generating data for scientific purposes (comparing gross gamma counts, investigating contamination
in the field, checking for contamination of a particular isotope, etc) the E600 is more of a heath physics unit and more focused on dose rates etc.
For what you are doing you will be less concerned about dose conversions and more interested in more specific data like comparing cpm data etc. For a
lot of field work (especially with NORM materials) I think you will find the scintillator probe more useful than the pancake probe. The pancake probe
will be "blind" to some low energy photons that are still easily detectable with a scintillator. For example, I have a calibrated 50,000 dpm I129
source, which is often used for low energy calibrations. I can put a pancake probe right on top of it and not see any increase in the count rate, but
with a scintillator probe I can easily detect the low-energy photons. Also, with a pancake probe you will have interference from beta particles (it's
hard to detect alphas in the field, what with self absorption and the fact they only travel a few centimeters in the air). Often you will find using
a gamma-only probe (like a scintillator) is most useful for detection in the environment. I use shielded pancake probes in the lab for analysis but
only after I spend time processing the samples and even then I'm only measuring a few grams (under 10g) at a time on a planchette.
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Yes, I have little interest in healthy physics readouts, I am only interested in raw counts. I think I need both a scintillation gamma probe for field
collecting (only gammas get through the air unless you on top of something), and a GM probe with an alpha window for lab work.
There is a Ludlum 1000 and 2000 scalers for only $300 on eBay right now, but they are bench units, not designed for field carry.
There are Ludlum 2241s on eBay also, one as cheap as $700 - within the range I was considering (a little higher, but better to get something good and
proper).
There are Eberline E600s available for only $250, which say they are scalers and are hand carry models. I'm not sure if they are sufficiently
versatile, taking different probes or not. |