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Abort Gap Cleaning Procedures

Abort Gap Cleaning Procedures. This is a proposal to be discussed To be applied for proton operation = 2012 Do we need to do / test something with ions now? AGC for ions is not set up yet Could practice procedure with adapted limits (lower), see later

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Abort Gap Cleaning Procedures

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  1. Abort Gap Cleaning Procedures • This is a proposal to be discussed • To be applied for proton operation = 2012 • Do we need to do / test something with ions now? • AGC for ions is not set up yet • Could practice procedure with adapted limits (lower), see later • Proposal based on the following observations • Ideally leave AGC on at full energy, continuously • This costs a few percent of luminosity per fill • If used at nominal strength and full length = most effective cleaning, long tail of cleaning pulse affects most bunches • Bunches closest to abort gap affected most • However, bunches don’t seem to be blown up by cleaning • Cleaning with shorter pulse and/or 50 % strength is not at all as effective, observed when dropping RF voltage • Hardware checks for coming Christmas TS • Measure ADT cables • Check Tetrode balancing • Possible hardware improvements for LS1 • If AGC switched on with too high abort gap population, order of 1e12, the losses on the TCP collimators risk to dump the beam at the worst moment (with very large AG population) LIBD meeting, Jan Uythoven

  2. BSRA protons, few days in October Very few occasions with AG population > 1e10 Clean at 3.5 TeV 1e10 4e9 LIBD meeting, Jan Uythoven

  3. Proposal • Have LHC announcer active. • Message if intensity above 5e9 p+ in AG • Intensity which is just above “normal population”, so one should activate the cleaning some times per week during normal operation • As BSRA is not 100 % reliable, it needs to be manual procedure • Operator to check abort gap population • Do we need another fixed display, the logging seems to be more reliable and easier to check than the BSRA application which does not show a history • If Abort Gap population >5e9 p+ and <1e12 p+: Switch on abort gap cleaning • With 50 % of nominal strength and full length, observe losses • If • population not decreasing in about a two minutes to < 4e9 p+ • Losses at BLMs < 25 % of dump limit • Clean with 100 % of nominal strength and full length • If population < 4e9 p+ switch cleaning off again • If population >1e12 p+ • Wait until “naturally cleaned” until < 1e12 p+ • Then switch on cleaning in two step as mentioned above LIBD meeting, Jan Uythoven

  4. Could already try this with ions ‘now’ AGC with ions to be commissioned Set announcer limit to 2e9 charges Upper limit for not switching it on ???? LIBD meeting, Jan Uythoven

  5. Future developments • Hardware on ADT side (see first slide) • Tests with stronger cleaning over a shorter period • Dedicated application for 2012 (Verena) • Shows fixed display of population from BSRA • Take into account BSRA validation flag • Facilitate changing of cleaning parameters, can possibly automatically be adjusted depending on AGC measurement • Cleaning length and amplitude • If the BSRA is that important ask BI for • A more reliable BSRA system • Similar, but redundant BSRA system LIBD meeting, Jan Uythoven

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