European Organisation for Nuclear Research European Laboratory for Particle Physics Technical Note Tis-rp/tn/2002-018 the Effect of a Beam Loss at the Ps/n_tof Interface of the Cern Ps Complex

This paper discusses the potential radiation hazard caused by beam losses in one of the transfer lines (TT2) of the CERN Proton Synchrotron, close to the point where the beam is split and can be directed towards the Super Proton Synchrotron via the TT10 tunnel, sent to the n_TOF experiment installed in the extension of TT2 (TT2A tunnel), or stopped in a massive dump. The TT2 area is separated from the downstream TT2A zone of n_TOF by a 4.8 m thick concrete wall. A full beam loss in TT2 could generate a serious radiation hazard on the TT2A side of the shielding wall. Several beam loss scenarios were investigated by Monte Carlo simulations performed with the FLUKA code. The various radiation components making up the dose equivalent rate in TT2A were assessed. It was found that the dose equivalent is dominated by either muons, mainly originating from pion decay, or neutrons produced in hadronic cascades inside the shielding wall, depending on the point where the beam is lost. A comparison between simulation results and measurements is made. CERN, Geneva, Switzerland 5 April 2002