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Answer to Question #2478 Submitted to "Ask the Experts"Category: Instrumentation and Measurements — Instrument Calibration (IC) The following question was answered by an expert in the appropriate field: Q
I am developing an aerosol particle size neutralizer using electronless deposited 63Ni as the source. I wish to seal the nickel foil source away from the particles passing through the radiation field using glass tubing. My question is whether the 63Ni will still exert an influence upon the particles in this glass tube, or will they simply be "protected" by the glass—thereby rendering the neutralizer ineffective?
A
Nickel-63 (63Ni) has a very low beta energy—about 66 kiloelectron volts (keV) max and 17 keV on average. It is often used for an opposite application and is used on plated foils to ionize molecules in gas chromatography units. The maximum range of this beta is about 7 milligrams per cm2, which is the average thickness of the dead cell layer of skin on your body. Also, my experience with the circa 1950 hand-blown thin-wall glass Geiger-Mueller tubes is that the best an experienced glass blower could do was about 15 mg/cm2 mass area wall thickness. Thus, for any practical glass tube shielding the 63Ni beta source, it will not produce the ionization you desire to neutralize particle surface charge. Though not as easy to license, you may look at a sealed 90Sr/90Y source.
David J. Allard, CHP
Answer posted on 27 April 2003. 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.
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