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Answer to Question #1927 Submitted to "Ask the Experts"Category: Accelerators — Induced radioactivity The following question was answered by an expert in the appropriate field: Q
Do the structural materials of which a cyclotron are constructed retain any form of long-term (greater than 20 years) radiation after the cyclotron is dismantled? In particular, I am asking about the copper coils and other initially nonradioactive metals.
A
In general, most of the activity in accelerator components and surrounding material, such as shielding, is short lived. To predict specific amounts of particular nuclides one needs to know the exact material composition (including impurities), the energy of the primary beam, and the geometry of the beamline components and surrounding environment. Activation is generated by the primary beam and secondary neutrons. There will be a greater variety of activated species at higher energies where spallation is likely to occur. Among the many activation products encountered at accelerators, the following have half-lives longer than one year:
The second column indicates the half-life in years and the third in what material this nuclide is generated. If you would like to make estimates of produced activity for your particular facility, I would suggest several references: Barbier M. Induced radioactivity. New York: John Wiley & Sons; 1969. Silberberg R, Tsao CH. Astro. Phys. J. Suppl. 25: 315-333; 335-368; 1973. - two papers Accelerator Radiation Protection. Special issue of Radiation Protection Dosimetry, 96 (4) 2001 - several papers in this issue talk about and provide further references on activation (for example, papers by Moritz, Stevenson, Silari . . .).
Answer posted on 20 May 2002. 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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