Beam loss simulation of SNS LINAC

We are developing a sophisticated system of beam loss pattern evaluation and residual radiation estimation. We have installed a number of neutron detectors (ND) and ionization chambers along the SNS LINAC. In this paper we present our implementation and simulation of the losses by inserting Faraday cups, using beam stops and running wire scanners at different energies. The measured losses are simulated by 3-D transport codes (GEANT4, SHIELD, MCNPX). We compare two different sets of beam loss monitors (BLM): ionization chambers (detecting X-ray and gamma radiation) and photomultiplier tubes with a neutron converter (detecting neutrons) and show that such a combination is a better way to measure beam losses than relying on detectors of only one type. We interpret the loss signal in terms of beam current lost in the SNS LINAC with accurate longitudinal loss distribution and plan to automate beam steering according to loss-monitor readings by using a loss pattern database developed by simulating different loss scenarios with the transport codes.