Design and operation of the H4IRRAD mixed-field test area at CERN

Abstract

H4IRRAD is a new mixed-field irradiation area at CERN, designed for testing LHC electronic equipment, especially large volume assemblies such as full electronics racks of high current power converters. The area uses alternatively an attenuated primary 400 GeV/c proton beam slowly extracted from the CERN SPS, or a secondary, mainly proton, beam of 280 GeV/c directed towards a 1 m long, 7.5 cm diameter Cu target. Different shielding layers are used to reproduce a radiation field similar to the LHC “tunnel” and “shielded” areas in test zones around the target. The FLUKA Monte Carlo code was used for the design and optimization studies with the objective to match, as closely as possible, the mixed-radiation fields in the LHC ring, whilst also maintaining the lowest possible field gradient within the irradiation areas. Activation studies for the target, equipment, and the air volume were performed in order to assess safety risks, specify the access conditions and determine how to handle the equipment after irradiation. The test area has been in operation since 2011 with numerous tests performed already. The design concept of H4IRRAD, along with comparison studies between the FLUKA predictions and the measurements for the mixed radiation field characterization will be presented in this paper.