BEAM LOSS CONTROL IN THE ISIS ACCELERATOR FACILITY

The ISIS spallation neutron and muon source has been in operation since 1984. The accelerator complex consists of an H - ion source, 665 keV RFQ, 70 MeV linac, 800 MeV proton synchrotron and associated beam transfer lines. The facility currently delivers ~2.8x10 13 protons per pulse (ppp) at 50 Hz, which is shared between two target stations. High intensity performance and operation are dominated by the need to minimise and control beam loss, which is key to sustainable machine operation allowing essential hands on maintenance. The dominant beam loss in the facility occurs in the synchrotron due to high intensity effects during the H - injection and longitudinal trapping processes. Losses are localised in a single region using a collector system. The measurement, simulation and correction systems for these processes are described. Emittance growth during acceleration can also drive extraction and beam transport loss at 800 MeV measurement and control systems for these are also outlined.