CMS Bulletin

UPGRADES

Good progress is being made on the projects that will be installed during LS1. CSC chamber production for ME4/2 is progressing at a rate of four chambers per month, with 25 built so far, and the new electronics for ME1/1 is undergoing a pre-production integration testing. For the RPC chambers, gap production is underway with first deliveries to the chamber assembly sites at CERN and Ghent. The third site at Mumbai will begin production next month. For the PMT replacement in the forward hadron calorimeters (HF), the 1728 PMTs are all characterised and ready to be installed. Testing of the electronics boards is going well. Preparations to replace the HPDs in the outer calorimeter (HO) with SiPMs are also on-track. All components are at CERN and burn-in of the new front-end electronics is proceeding.

There are three major upgrade projects targeting the period from LS1 through LS2: a new pixel detector, upgraded photo-detectors and electronics for HCAL, and development of a new L1 Trigger. The new pixel detector will provide more robust tracking with four barrel layers and three disk stations at each end, and higher data bandwidth with a new readout chip and DAQ. The HCAL upgrade replaces the present HPDs with SiPM photo-sensors and a new DAQ. The improved signal-to-noise ratio of SiPMs with an optimised DAQ will allow depth segmentation and improved timing to mitigate event backgrounds and pile-up. The Trigger upgrade will provide improved granularity and isolation in the calorimeter triggers and more robust tracking for muons. With these three upgrades CMS will continue to perform well at the significantly higher pile-up anticipated beyond LS1.

Technical Design Reports were presented to the LHCC in September for the pixel and HCAL upgrades. The reports describe the motivation for the upgrades, the performance of the new detectors, detailed technical descriptions and a summary of the project organisation, cost and schedule. A strong emphasis was placed on the performance studies, carried out under Physics Coordination where the PAGs applied realistic analyses with simulated data. This involved a concerted effort including Offline, PPD and Computing Coordination to produce and validate the samples. The TDRs were well received and the committee concluded, “The LHCC endorses the HCAL and pixel Upgrades without reservations.” The cost information was then presented to the RRB in October and the projects are now proceeding to formalise MOU and prepare for Engineering Design Reviews. Both projects will ramp up rapidly in 2013.

A TDR for the L1 Trigger Upgrade is in preparation, again with extensive simulation studies involving the Physics, Offline, PPD and Computing coordination areas. We expect to submit this TDR to the LHCC in early 2013, and the project to again ramp up rapidly in 2013.

Studies are on-going to understand the performance longevity of the detector systems in terms of radiation damage and ageing, as input for developing the scope of the Phase 2 upgrade planned for LS3. At the same time the Tracker project and the working groups for the Trigger Performance and Forward Detector are developing requirements and options for Phase 2. The goal is to document the performance longevity of the Phase 1 detector, and the Phase 2 requirements and options by summer 2013 to provide a basis for a Technical Proposal in 2014.