CERN Super Proton Synchrotron Radiation Environment and Related Radiation Hardness Assurance Implications

Abstract

The Super Proton Synchrotron (SPS) is the second largest accelerator at CERN where protons are accelerated between 16 GeV/c and 450 GeV/c. Beam losses, leading to the mixed-field radiation of up to MGy magnitude, pose a threat to the reliability of the electronic equipment and polymer materials located in the tunnel and its vicinity. Particularly in the arc sectors, where both main magnets and radiation sensors are periodically arranged, the Total Ionizing Dose (TID) is of concern for the front-end electronics of A Logarithmic Position System (ALPS). The SPS is equipped with multiple radiation detection systems such as Beam Loss Monitors (BLM), RadMons, and as of 2021, the Distributed Optical Fibre Radiation Sensing (DOFRS), that combined all together provide a very comprehensive picture of both the TID spatial distribution and its time evolution. Within this study, the overview of measured 2021 and 2022 TID levels is presented, together with the demonstration of capabilities offered by the different radiation monitors. The DOFRS, supported by the passive Radio-Photo Luminescence (RPL) dosimeter measurements, is used to assess the TID values directly at the electronic racks, which turned out to be reaching several tens of Gy per year, potentially affecting the ALPS lifetime.