Operational experience with high beam powers at ISIS
Findlay DJS., Allen GM., Arnold MA., Bayley DL., Brodie R., Burridge RA., Carter TE., Christie JD., Clarke-Gayther MA., Davies MB., Faircloth DC., Gardner ISK., Glover MG., Govans JAC., Grafton ND., Gray JW., Haynes DJ., Hughes S., Izzard T., Jones B., Jones HJ., Keelan M., Kershaw AH., Krendler M., Lambourne CR., Letchford AP., Loughrey JP., McCarron EJ., McFarland AJ., Mannix RP., Nobbs AJ., Noone T., Patel S., Payne SJ., Pearce LJ., Perkins M., Perry GJ., Randall LJ., Ruddle MJ., Ruddle SJ., Scaife I., Scott AM., Seville A., Stevens AF., Thomason JWG., Vickers JA., Warner S., Warsop CM., Wright PNM.
ISIS is currently the world's most productive spallation neutron source. A total beam power of ∼0.2 MW is delivered by a 70 MeV H - linac and an 800 MeV rapidly cycling proton synchrotron to two target stations, one which has been running since 1984, and a second which is being commissioned this year (2008). ISIS runs for typically ∼200 days each year scheduled as some five ∼40-day user cycles, although shutdowns lasting several months for major maintenance and upgrade work took place in 2002, 2004 and 2007 (during user cycles ISIS runs 7 days/week, 24 hours/day, and the ∼200 days excludes run-up and machine physics time). In order to enable hands-on maintenance régimes to prevail, considerable efforts are made to minimise beam losses during operations, and engineering design of accelerator and beam line components specifically includes measures to limit radiation doses to personnel. This paper covers these issues and others - including the difficult balances to be struck between operations, maintenance and upgrade work.