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29 August 2008

Answer to Question #1140 Submitted to "Ask the Experts"

Category: Instrumentation and Measurements — Instrument Calibration (IC)

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

Can water be used as an effective liquid scintillation fluid?

When relatively energetic beta particles pass through a transparent medium of high refractive index such as water, a bluish "Cerenkov" light is emitted. However, with Cerenkov radiation production there is a threshold energy for the effect, which is a function of the refractive index. Also, the light output with water is less than from liquid scintillators. Nevertheless, this light may be detected using modern liquid scintillation counting equipment. The light output and counting efficiency is a function of the beta energy, quenching of the sample, etc. Most radiation detection and measurement text books explain this effect, but I found a brief discussion of Cerenkov counting on the IN/US (the Radiochromatography Company) Web site.

David J. Allard, CHP

Answer posted on 30 August 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.