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24 May 2012

Answer to Question #2522 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:

What methods are available to distinguish between different radionuclides? For example, how do I determine whether a radionuclide is strontium-90 or carbon-14?

If you have a gamma emitter, a count with a GeLi or NaI gamma spectroscopy system will provide a spectrum, unique to the radionuclide(s) present. For the pure beta emitters as you've noted, an attenuation experiment where you determine the maximum range (i.e., counts go to background) in milligrams per square centimeters is a method to determine an estimate of the maximum energy of the beta. You could deduce the radionuclide from that energy information (e.g., strontium-90/yttrium-90 has a beta max of 2.28 MeV which has about a 1000 mg/cm² range). Also, modern liquid scintillation units should provide a display of the beta spectrum. Again, a determination of the beta max energy should provide the insight needed to determine the radioisotope present.

David J. Allard, CHP

Answer posted on 9 April 2003. The information and material posted on this website 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 Website. 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.