Assessment of occupational exposures around high-energy photon accelerators

At CERN, the European Laboratory for Particle Physics, three high-energy proton accelerators are in operation: a 600 MeV Synchro-cyclotron (SC), a 28 GeV Proton Synchrotron (PS) and the 450 GeV Super Proton Synchrotron (SPS). In conjunction with the accelerators mentioned above occupational exposures to various types of radiation are of concern. As around nuclear reactors, the main source of radiation causing personal exposures is gamma radiation from activated accelerator components during accelerator shutdown periods. During operation of the accelerators, exposures to hadrons (mainly neutrons), covering a wide energy range in experimental areas, and to high-energy muons downstream of primary proton beam targets have to be considered. Outside controlled radiation areas occupational exposures are derived from a system of passive thermoluminescence detectors (TLD) used for area monitoring, while inside controlled radiation areas individual dosimeters are worn. This paper describes the systems used at CERN for monitoring of exposures