ISIS upgrades - A status report

Since 2002 several accelerator upgrades have been made to the ISIS spallation neutron source at the Rutherford Appleton Laboratory in the UK, and upgrades are currently continuing in the form of the Second Target Station Project. The paper reviews the upgrade processes, and looks forward to possible future schemes at ISIS beyond the Second Target Station. ISIS SPALLATION NEUTRON SOURCE The ISIS spallation neutron source (then simply called SNS) produced its first proton beam on 16 December 1984. At that time it was configured as a 665 kV Cockcroft-Walton preinjector, a 70 MeV H – 4-tank drift tube linac, and a 26 m mean radius 800 MeV proton synchrotron with a cycling rate of 50 Hz driving a depleted uranium target * . The proton synchrotron was built in the hall originally constructed in the 1950s for the 7 GeV proton synchrotron Nimrod, and the CockcroftWalton and linac were originally built as a new high energy injector for Nimrod. But Nimrod closed down in 1978, and the new 70 MeV injector was never used for Nimrod, but was converted from 1 Hz 75 mA proton operation to 50 Hz 20 mA H – operation.