CMS Bulletin

MUON DETECTORS: CSC

The CSC muon system has run well and very stably during the 2012 run. Problems with the delivery of low voltage to 10–15% of the ME1/1 chambers were mitigated in the trigger by triggering modes that make use of coincidences between stations 2, 3, and 4. Attention now focuses on the ambitious upgrade program in LS1. Simulation and reconstruction code has been prepared for the post-LS1 era, for which the CSC system will have a full set of 72 ME4/2 chambers installed, and the 3:1 ganging of strips in the inner section of ME1/1 (pseudorapidity 2.1–2.4) will be replaced by flash digitisation of each strip.

Several improvements were made to the CSC system during the course of the year. Zero-suppression of the anode readout reduced 15% from the CSC data volume. The response to single-event upsets (SEUs) that cause downstream FED readout problems was improved in two ways: first, the FED monitoring software now detects FEDs that are stuck in a warning state and resets within about 4 seconds, instead of several minutes previously with the DAQ shifter’s manual intervention. Second, the FED monitoring software now separates SEU errors from other (hardware) types of errors, and a “zero-tolerance” policy removes all of the SEUs by hard resets. Previously up to eight chambers were allowed to be in error before such a reset was issued.

The chamber factory at B904 now runs smoothly, turning out at least the anticipated one chamber per week. Temporary problems with wire breakage and the wire tension measuring machine were swiftly overcome. The factory has produced 27 of the necessary 67 chambers, and 17 are fully instrumented, tested and ready for installation at P5.

A full set of pre-production DCFEBs, the on-chamber boards used for strip digitisation in the ME1/1 upgrade have been installed on a test chamber at B904 and put through their paces; only minor issues remain to be addressed. An upgrade to the on-chamber ALCT mezzanine board will be installed on ME1/1 as well as ME4/2 chambers (50 out of 160 have been produced). Among off-chamber electronics, the OTMB mezzanine card has passed many tests, while the ODMB is undergoing rework, as an ASIC used for optical control of the DCFEBs will not be ready in time. A new low-voltage system that supplies more current to the ME1/1 electronics has been planned out and is now being prototyped. Reviews of the upgrades will be coming soon: a DCFEB PRR on 6 December, and ME1/1 ESR and ME4/2 MPR likely to happen in February.

A workshop held on 15–16 November on CSC planning for LS1 made it clear to the group that a large task is ahead in 2013, when electronics must be ready for ME1/1 and chambers for ME4/2, after which a great deal of careful installation work and testing must be done. The CSC group is being asked to supply additional effort, and some reorganisation around LS1 task forces will take place during the December CMS Week.