Activation Models of the ISIS Collectors

Abstract

The ISIS facility at the Rutherford Appleton Laboratory is a pulsed neutron and muon source, for materials and life science research. The 163 m circumference, 800 MeV, 50 Hz rapid cycling synchrotron accelerates up to 3×10 protons per pulse. The maximum operating intensity of the synchrotron is limited by loss during acceleration, mainly due to the non-adiabatic longitudinal trapping process between 0 and 3 ms, corresponding to energies between 70 and 200 MeV. In order to minimise global machine activation and prevent component damage a beam collimation, or collector, system is installed in a five metre drift section in super-period one, to localise loss to this region. This paper summarises new results from modelling of the beam collectors using the FLUKA code [1, 2]. Understanding the current performance of the collectors is important for high intensity beam optimisation and may influence future injection upgrade plans. Residual dose rates are compared to film badge measurements, predicted energy deposition results are compared to the measured heat load on the collector cooling systems and an assessment is made of the distribution of particles exiting the collector straight.