5-Jan-2010 XEB Meeting at CERN 1 Debriefing from first data: CSC muons n Lessons learned u LHC is a quiet machine  CSC HV can remain on at all times, at least at current beam intensities u Beam halo rates are small (both and  ) u CSC trigger timing seems okay, but statistics are very low n Main concerns u Plumbing: even if YE+-1 are fixed, a leak in YE2 will kill most of our trigger capability (knocks out both ME2 and ME3)  CSC |  |>1.6 and beam halo event streaming needs our attention l Did we lose beam halo events? Quality cuts that depend on non-existent (TDR) RPC chambers at high  e.g. HLT_l1Mu20HQ u Only some 10’s of CSC collision events, not enough yet to tune: l Time synchronization l DT overlap region trigger l Alignment n Proposed actions u Fix plumbing… u Study CSC muon and beam halo event streaming from L1 through HLT and Tier-0 u Take data, and tune trigger timing and CSC chamber alignment

5-Jan-2010 XEB Meeting at CERN 2 Backup slides

5-Jan-2010 XEB Meeting at CERN 3 Example: min bias vs. beam halo rates n From CSC elog of 13-Dec n Beam halo trigger: u Most of the rate is cosmic rays (0.6 Hz) u Beam halo rate was at most ~0.1 Hz Min bias Beam halo trigger NB 1-hour shift from GMT (plots on right)