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News etc. HCAL General Meeting April 7, 2011. LHC. Scrubbing 50 ns bunch trains at 450 GeV (up to 300 bunches per train, keeping losses <50% of beam dump threshold – or something like that ). CMS magnet OFF. Vacuum near CMS with magnet off….
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News etc HCAL General Meeting April 7, 2011
LHC • Scrubbing • 50 ns bunch trains at 450 GeV (up to300 bunches per train, keeping losses <50% of beam dump threshold – or something like that). CMS magnet OFF. • Vacuum near CMS with magnet off…. • Possible short run at 3.5TeV to measure improvement. CMS magnet off. • Some optimism about progress hope for 50ns… • Note that the short magnet off running will be at 50ns – can we use it? • Longer range planning – discussion between CERN+Experiments • 2013-14 shutdown length: 16 months of access work satisfies all parties • (~19 months beam to beam (including quench training), physics to physics gap will be longer (commission at 13[?] TeV)) • Linac4 and full collimator upgrade cannot be ready for a summer 2014 restart – they need ~6 more months. With these, luminosity >E34 possible • Discussion: Dec 2012 - summer 2014, or slide start to ~May 2013 • If 13-14 shutdown moved back 6 months, second long shutdown ~2018 • And CMS would ask for >4month ETS ~2016 to install new pixel detector (note: new beam pipe installed in 2013-14 (also benefits from 6mo more) • Discussion likely to firm up by May. Implications for HCAL upgrade planning
Scrubbing, Magnet, Vacuum • LHC sees very high losses at CMS with the solenoid off compared to on, and vacuum degrades up to 50m from IP! (Same effect seen at other experiments)
HCAL • RBX data loss: semi-auto recovery • Exercising the alarm reset button functionality • Must confirm mechanism for data certification • Aim to hand over to central shift in ~2 weeks • HCAL noise in jet triggers • Implement noise cleaning in HLT • HF-iso (L-S)/(L+S) ready to go (no change with bunch spacing • HF-timing/pulse shape (depends on bunch spacing), • HBHE noise filters • (2) and (3) require “retuning for 2011 beam conditions • HF pre-triggering • Even though the actual rate is low – it is a biased sample (likely hood of an event vetoing itself increases with event complexity) • Two options (do both?): • Isolation filter in the HF TP – code already in place, under study • Add BTPX as a BX-1 veto – trigger input being prepared • Document reco flags in offline and HLT
Pledging • CMS PLEDGING WILL CLOSE AT THE END OF APRIL • HCAL is in the middle of the pledge acceptance process – there is a lot of cleaning up to do. • Need all pledging NOW • First round of acceptance will be reviewed, then a second round. • Must complete BEFORE the end of April. • Current snapshot: