Radiation shielding for high energy muons: The case of a cylindrically symmetrical shield and no magnetic fields

Abstract

At proton accelerators with energies of tens of geV and more, the shielding problems are dominated by the requirement of reducing the flux of muons to tolerable levels. This is especially true for accelerators making extensive use to extracted proton beams. We present a technique for calculating the profile of the radiation shield for muons for a number of practical situations of interest, viz., beam loss in an internal target area, beam loss during transport of the extracted proton beam down a long narrow pipe, and the case in which the extracted proton beam is dumped in a backstop. Results obtained from a computer program are presented graphically for different possible shield materials — heavy concrete, iron, lead, and depleted uranium. The results span four orders of magnitude in muon flux normalized to the rate of interacting protons, so that one can obtain useful results by interpolation for a wide variety of beam loss and desired shielding situations. The primary proton energies used in the calculations −25, 70, 200 and 300 GeV - will be recognized as corresponding to the energies of proton accelerators at present either operating or under design.