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04 July 2009

Answer to Question #1330 Submitted to "Ask the Experts"

Category: Instrumentation and Measurements — Instrument Calibration (IC)

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

I want to ask about gamma-ray spectroscopy and gamma-ray penetration of different types of soil and types of gamma-ray detectors.

In situ gamma-ray spectroscopy of soil is quite common for surveys of natural background (that is, uranium and thorium series) or man-made radionuclides. Often a sodium iodide (NaI) or germanium detector is used with a multichannel analyzer. Whatever is used, if you don't see the natural radioactive material—for example, ⁴⁰K gamma rays—in the measurements, you've got a problem. A good source of information on this subject is the Department of Energy's Environmental Measurement Lab's manual No. HASL-300. The section on calibration will provide the appropriate equations for such measurements. Also see the NCRP Report No. 50 on "Environmental Radiation Measurements."

David J. Allard, CHP

Answer posted on 5 November 2001. The information and material posted on this Web site is intended as general reference information only. Specific facts and circumstances may alter the concepts and applications of materials and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice specific to whatever facts and circumstances are presented in any given situation. Answers are correct at the time they are posted on the Web site. Be advised that over time, some requirements could change, new data could be made available, or Internet links could change. For answers that have been posted for several months or longer, please check the current status of the posted information prior to using the responses for specific applications.