LHC Scrubbing Run 1 Day 3 (27/06/2015) Scrubbing team 28/06/2015

Overview LHC 8:30 meeting2 Fill 3911: 372 b. in both beams 24 bunches per injection

Overview LHC 8:30 meeting3 Fill 3912: 24 bunches per injection Lost sector 23 (5h stop)

Overview LHC 8:30 meeting4 Fill b. in B1 588b. in B2 Tested injections of 36b.  OK Tested injections of 48b.  dumped by injection losses  increased scraping at SPS

Overview LHC 8:30 meeting5 Fill b. in B1 588b. in B2 Tested injections of 36b.  OK Tested injections of 48b.  dumped by injection losses  increased scraping at SPS

Overview LHC 8:30 meeting6 Fill 3915 Test with 48b. per injection  Unstable in both planes Roll back to 36b. per injection

LHC 8:30 meeting7

Overview LHC 8:30 meeting8 Fill b. per injection Dumped B1 soon after first injections of B2, interlocked BPM

Overview LHC 8:30 meeting9 Fill 3417 Test with Stability does not improve

Overview LHC 8:30 meeting10 Fill b. per injection Reached up to ~ b Mainly dumped by V instability but anyway strong beam degradation when kept

Overview LHC 8:30 meeting11 Fill 3425 Injected 228b. in B1, 210b. in B2 Kept in the machine in spite of the decreasing heat load due to PS extraction problem

Overview LHC 8:30 meeting12 Fill 3425 Injected 228b. in B1, 210b. in B2 Kept in the machine in spite of the decreasing heat load due to PS extraction problem

Overview LHC 8:30 meeting13

Both MKIs condition well 25ns Start lower: NEG coating in Cu tube

Comparison with 2012 after MKI exchange during TS 25ns Start lower: NEG coating in Cu tube Start lower: NEG coating in Cu tube 25ns After MKI8D exchange 2012

Summary o Continued scrubbing with 25 ns beams o Operation with 25 ns still looks very challenging at this stage For trains of 24b+ instabilities right after injection are observed and often lead to beam dumps for trains of 36b+ (even with extremely high Q’) When enough beam is stored, strong heat load is observed in the arcs Very poor lifetime  can be improved by trimming down chroma at store o Scrubbing evolution is observable but the pace is quite slow Slower than in  much more difficult to keep long trains in the LHC o To speed up the process, a better control of the instability is desirable Any optimization possible on ADT side? o Possible next steps: Accumulate more beam dose with 25 ns before switching back tomorrow to 50 ns to complete the intensity ramp up (benefiting from the 48h scrubbing with 25 ns) LHC 8:30 meeting16