Abstract
The HL-LHC phase is designed to increase by an order of magnitude the amount of data to be collected by the LHC experiments. To achieve this goal in a reasonable time scale the instantaneous luminosity would also increase by an order of magnitude up to 6 · 1034 cm−2s−1. The region of the forward muon spectrometer (|η| > 1.6) is not equipped with RPC stations. The increase of the expected particles flux up to 2 kHz/cm2 (including a safety factor 3) motivates the installation of RPC chambers to guarantee redundancy with the CSC chambers already present. The current CMS RPC technology cannot sustain the expected background level. The new technology that will be chosen should have a high rate capability and provide a good spatial and timing resolution. A new generation of Glass-RPC (GRPC) using low-resistivity glass is proposed to equip at least the two most far away of the four high η muon stations of CMS. First the design of small size prototypes and studies of their performance in high-rate particles flux are presented. Then the proposed designs for large size chambers and their fast-timing electronic readout are examined and preliminary results are provided.
Highlights
- Design, construction and front end electronics of second station of Forward Muon Spectrometer in ALICE Pratap Bhattacharya
These results show that the single gap Tsinghua Low Resistivity (LR) GRPCs by themselves already fulfil the CMS HL-LHC upgrade requirements: if the single gap efficiency is ≈ 70%, the double-gap efficiency, 2 = 1 − (1 − )2 > 90%
A new kind of GRPC detectors is proposed to equip some of the high η muon stations of CMS
Summary
The dimensions of the first prototypes are constrained by the largest size of the low resistivity glass plates that could be produced currently: 30 × 32 cm2 [4]. Prototypes sketched in figure 2 (top): a gas gap of 1.2 mm separates two 1 mm thick low resistivity glass plates covered with a colloidal graphite coating (surface resistivity of about a few MΩ/ ). The strips have the same direction on each side, are read by 4 ASICs, have a pitch of d = 2.5 mm, are separated by 0.5 mm and have an impedance of 24 Ω. The strips of one side are shifted by 1 mm with respect to those of the other side in the direction perpendicular to the strips one (see figure 2 (bottom)) This configuration, referred to as double-gap, is designed to increase the spatial resolution by looking at the coincidence of fired strips in the two layers
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