CMS Bulletin

MUON DETECTORS: DT

The DT collaboration is undertaking substantial work both for detector maintenance – after three years since the last access to the chambers and their front-end electronics – and upgrade.

The most critical maintenance interventions are chambers and Minicrate repairs, which have not begun yet, because they need proper access to each wheel of the CMS barrel, meaning space for handling the big chambers in the few cases where they have to be extracted, and, more in general, free access from cables and thermal shields in the front and back side of the chambers. These interventions are planned for between the coming Autumn until next spring. Meanwhile, many other activities are happening, like the “pigtail” intervention on the CAEN AC/DC converters which has just taken place.

The upgrade activities continue to evolve in good accordance with the schedule, both for the theta Trigger Board (TTRB) replacement and for the Sector Collector (SC) relocation from the UXC to the USC. The TTRB work aims at reconstituting the stock of spare boards for the long-term operation of the chamber Minicrates. Theta TRB production is going on satisfactorily: soon we will have the first batch of boards at CERN. With the SC work, data and trigger primitives from each of the 250 DT chambers will be available in the USC on optical fibres. This work is the cornerstone for any long-term upgrade plan of the DT system. All but one optical-fibre trunk cables have been received, measured and are ready for installation between the USC and the UXC.
Half of the Wiener crates have been received and tests are satisfactory.
A first batch of final OFCU-RO boards is being tested: no problems so far.
Final production has also been started for the first batch of CUOF mezzanines and of OFCU-TRG boards.
CUOF motherboard slow control tests worked fine.
Cooling tests for the CUOF crate have started at the building 904 site, where a peak of activity is being reached with many tasks carried out in parallel: CAEN modules test stand refurbishment, slow control developments, Minicrate installation logistics etc.

Finally, a DT Upgrade workshop on detector longevity and Phase 2 upgrade strategies was held in Padova: the data on electronics irradiation tests were reviewed and the decision to rebuild the Minicrates was taken in the end, aiming at their installation during LS3. The DT DPG group has started studies for simulating the muon barrel performance in scenarios of increasing degradation due to ageing of the detector.