Answer to Question #7442 Submitted to "Ask the Experts"

Category: Instrumentation and Measurements — Surveys and Measurements (SM)

The following question was answered by an expert in the appropriate field:

Can you advise me on manufacturers of small-area alpha probes? I would like to purchase alpha probes that can be inserted down small apertures of diameters between 3 cm and 5 cm.

There are some small-dimension radiation detectors that are available; many of these are beta and/or gamma detectors, but there are some alpha probes. I cannot tell from your question the particular source geometry that you are concerned with, and some detectors may be more suitable than others, depending on the geometric characteristics of the source(s).

There are some detectors that are intended for doing surveys of the internal surfaces of pipes, and these might be useful. Here is a link to one such, the PDP-2L gas flow proportional detector from Technical Associates, a company that supplies a variety of detectors for various applications. Thermo Electron is now Thermo Scientific, another company that provides various detectors. Depending on your geometry and sensitivity needs, you might be able to get away with a more economical end-window GM detector, Thermo; this detector has a 3.5 cm diameter. Another instrument company, Canberra, has a variety of mica end-window GM probes (click on “View full specifications" to see details), several with small diameters, that might be useful. A number of small-diameter end-window GM detectors can also be found at LND, Inc. Finally, there is a company in the United Kingdom called Centronic that also produces a large number of GM detectors of different sizes and designs as well as many other detectors.

I hope some of the above links will prove helpful. There are numerous other companies that produce detectors that might be useful. You can find many on the Internet by searching for radiation detectors; including verbiage more descriptive of your needs will help narrow the search. Good luck.

George Chabot, PhD, CHP

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