Expert opinions sought on a good Radiation meter

Submitted by Anonymous on Fri, 2012-03-16 08:06

I found this comment on ENEnews and I am wondering if this is a good way to start examining food items, etc for radioactive content.
I suspect it is a clever spam message to sell a product.
But is it good or would something like the Radiation Inspector be the way to go? http://radiationinspector.com/

****************** Comment I found
Spectrometising
March 16, 2012 at 10:54 am Log in to Reply
Really annoying to see geiger pushers, pushing giegers. nO WHERE NEAR AS SENSITIVE AS SCINTILLATION DETECTORS.

A gamma scintillator and a pancake detector are the best in my opinion.

Get one of these for 250$
http://www.ebay.com.au/itm/GS-1100A-USB-Gamma-Scintillator-Driver-Spectr...
(Read the fine print….This is the basis for adding a family of detectors instead of being tied like a buffalo to post with a brand name product that will not work with any other detector and on and on…..Buying a brand name is a sure way to end up with a noose around the neck with no means of upgrading without buying an entirely new system.)

Then get either a Geiger detector stand alone and plug into the item above. Or a professional pancake style alpha, beta gamma detector.

Here is the free software that will even allow someone to do isotope analysis.
http://www.physics.usyd.edu.au/~marek/pra/index.html

This means the cost of a system that will do full gamma spectrometry is under 1000$

DO NOT WASTE MONEY AND RESOURCES LOCKING YOURSELF INTO A BRAND NAME.

Also, to do food testing some Lead sheild is a huge advantage …

That's my two bobs worth…

Or go to facebook and see what we are doing there at facebook page "Gamma Spectacular"
Or here..http://tech.groups.yahoo.com/group/GeigerCounterEnthusiasts/

Or here
http://tech.groups.yahoo.com/group/GammaSpectrometry/

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Cost of spectroscopy

Submitted by bandstra on Fri, 2012-03-30 23:47.

Pancake detectors are very similar to Geiger counters in that they do not perform spectroscopy. Gamma-ray spectroscopy can tell you what isotope is responsible for the radiation being measured, since each isotope has a unique "fingerprint" in gamma-rays.

If you are worried about food contamination, then you could just get a Geiger or pancake to do it. However, you should be ready for the fact that many items are naturally radioactive and therefore such measurements are pretty useless. These sorts of detectors are useful in a lab for finding areas that may have radioactive contamination, but they are lousy for finding small amounts of radioactivity among large amounts of natural radioactivity.

To do spectroscopy you would really need a scintillator crystal such as sodium iodide or lanthanum bromide. I doubt the claim that one can "do full gamma spectrometry [for] under 1000$" since even a small crystal will easily cost thousands of dollars. The crystal needs to be mounted in a light-tight container with a photomultiplier tube or photodiode. In addition, a high voltage power supply is needed, as well as a multichannel analyzer and computer for reading the spectrum. The item they mention there looks like it is intended to play the role of HV supply and MCA.

(I might point out that we use high-purity germanium, which offers much better spectral resolution than scintillators, but decent-sized crystals are measured in the tens of thousands of dollars...)

Mark [BRAWM Team Member]

Just curious, what keeps the

Submitted by Anonymous on Sun, 2012-04-01 22:28.

Just curious, what keeps the cost of these crystals so high?

Just like other crystals

Submitted by Anonymous on Mon, 2012-04-02 08:00.

It's like the cost of other crystals; like diamonds or other gems.

There's not a big market, and the cost of either finding or growing big crystals is just plain expensive.

Well, are these crystals

Submitted by Anonymous on Tue, 2012-04-03 08:27.

Well, are these crystals particularly rare? Lab-grown and very difficult to grow? Or is it just that there hasn't been much of a market for them?

The crystals are very

Submitted by bandstra on Tue, 2012-04-03 12:07.

The crystals are very difficult to grow, and some of the materials involved are rare. Scintillator crystals must be single, large (~inches) crystals in order to work properly, and it is hard to grow crystals of this size with no defects.

There is a very good market for these crystals; they have been the workhorses of gamma-ray spectroscopy for decades and will be for many to come. They are used extensively for medical imaging and radiation protection, among many other uses. There is also a great deal of research going into making newer and better crystals with more desirable properties. I don't see lower cost being one of these properties for the reasons explained above.

Mark [BRAWM Team Member]

Thanks for the answer, mark!

Submitted by Anonymous on Sat, 2012-03-31 09:06.

Thanks for the answer, mark! Tells me what I needed.

Identifinder

Submitted by Anonymous on Sat, 2012-03-31 02:30.

Mark,
Is a device like the "Identifinder" one that actually does spectrometry usefully?