A new approach for CMS RPC current monitoring using Machine Learning techniques

International audienceThe CMS experiment has 1054 RPCs in its muon system. Monitoring their currents is the first essential step towards maintaining the stability of the CMS RPC detector performance. The current depends on several parameters such as applied voltage, luminosity, environmental conditions, etc. Knowing the influence of these parameters on the RPC current is essential for the correct interpretation of its instabilities as they can be caused either by changes in external conditions or by malfunctioning of the detector in the ideal case. We propose a Machine Learning(ML) based approach to be used for monitoring the CMS RPC currents. The approach is crucial for the development of an automated monitoring system capable of warning for possible hardware problems at a very early stage, which will contribute further to the stable operation of the CMS RPC detector

Front-end electronics for CMS iRPC detectors

International audienceA new generation of resistive plate chambers, capable of withstanding high particle fluxes (up to 2000 Hz · cm-2) and instrumented with precise timing readout electronics is proposed to equip two of the four high pseudorapidity stations of the CMS muon system. Double-gap RPC detectors, with each gap made of two 1.4 mm High Pressure Laminate electrodes and separated by a gas gap of the same thickness, are proposed. The new layout reduces the amount of the avalanche charge produced by the passage of a charged particle through the detector. This improves the RPC rate capability by reducing the needed time to collect this charge. To keep the RPC efficiency high, a sensitive, low-noise and high time resolution front-end electronics is needed to cope with the lower charge signal of the new RPC. An ASIC called PETIROC that has all these characteristics has been selected to read out the strips of new chambers. Thin (0.6 mm) printed circuit board, 160 cm long, equipped with pickup strips of 0.75 cm average pitch, will be inserted between the two new RPC's gaps. The strips will be read out from both ends, and the arrival time difference of the two ends will be used to determine the hit position along the strip. Results from the improved RPC equipped with the new readout system and exposed to cosmic muons in the high irradiation environment at CERN GIF++ facility are presented in this work

CMS phase-II upgrade of the RPC Link System

International audienceThe present RPC Link System has been servicing as one of the CMS subsystems since installation in 2008. Although the current Link System has been functioning well for the past 13 years, the aging of its electronic components and lack of radiation hard ASICs could present problems for future operations. Additionally, the needs to have a more robust control interface against electromagnetic interference, to improve the trigger performance with finer time granularity and to incorporate a higher bandwidth transmission lines led the idea of upgrading the Link System for the HL-LHC. This paper reviews the features of the recently developed prototype of the new Link System

Experiences from the RPC data taking during the CMS RUN-2

International audienceThe CMS experiment recorded 177.75 fb−1 of proton-proton collision data during the RUN-1 and RUN-2 data taking period. Successful data taking at increasing instantaneous luminosities with the evolving detector configuration was a big achievement of the collaboration. The CMS RPC system provided redundant information for the robust muon triggering, reconstruction, and identification. To ensure stable data taking, the CMS RPC collaboration has performed detector operation, calibration, and performance studies. Various software and related tools are developed and maintained accordingly. In this paper, the overall performance of the CMS RPC system and experiences of the data taking during the RUN-2 period are summarised

Towards a two-dimensional readout of the improved CMS Resistive Plate Chamber with a new front-end electronics

International audienceAs part of the Compact Muon Solenoid experiment Phase-II upgrade program, new resistive plate chambers will be installed in the region at low angle with respect to the beam collision axis, in order to improve the detection of muons with a low transverse momentum. High background conditions are expected in this region during the high-luminosity phase of the Large Hadron Collider, therefore an improved-RPC design has been proposed with a new front-end electronics to sustain a higher particle rate capability and better time resolution. A new technology is used in the front-end electronics resulting in low achievable signal detection of 1–20 fC. Crucial in the design of the improved-RPC is the capability of a two-dimensional readout in order to improve the spatial resolution, mainly motivated by trigger requirements. In this work, the first performance results towards this two-dimensional readout are presented, based on data taken on a real-size prototype chamber with two embedded readout planes with orthogonal strips

Upgrade of the CMS resistive plate chambers for the high luminosity LHC

International audienceDuring the upcoming High Luminosity phase of the Large Hadron Collider (HL-LHC), the integrated luminosity of the accelerator will increase to 3000 fb$^{−1}$. The expected experimental conditions in that period in terms of background rates, event pileup, and the probable aging of the current detectors present a challenge for all the existing experiments at the LHC, including the Compact Muon Solenoid (CMS) experiment. To ensure a highly performing muon system for this period, several upgrades of the Resistive Plate Chamber (RPC) system of the CMS are currently being implemented. These include the replacement of the readout system for the present system, and the installation of two new RPC stations with improved chamber and front-end electronics designs. The current overall status of this CMS RPC upgrade project is presented

Aging Study on Resistive Plate Chambers of the CMS Muon Detector for HL-LHC

International audienceIn the High Luminosity Large Hadron Collider (HL-LHC) program, during the next years, the instantaneous luminosity will increase up to 5 × 1034 cm−2 s−1 which means a factor five higher than the nominal LHC luminosity. In that period, the present CMS Resistive Plate Chambers (RPC) system will be subjected to background rates higher than those for which the detectors have been designed, which could affect the detector properties and induce aging effects. To study whether the present RPC system can sustain the hard background conditions during the HL-LHC running period, a dedicated longevity test is ongoing at the CERN Gamma Irradiation Facility, where a few spare RPCs are exposed to high gamma radiation for a long term period to mimic the HL-LHC operational conditions. During the longevity test, the main detector parameters are continuously monitored as a function of the integrated charge. Preliminary results of the study, after having collected a sufficient amount of the expected integrated charge at HL-LHC, will be presented

RPC system in the CMS Level-1 Muon Trigger

International audienceThe CMS experiment implements a two-level triggering system composed of Level-1, instrumented by custom-design hardware boards, and a software High Level Trigger. To cope with the more challenging luminosity conditions, a new Level-1 architecture has been deployed during run II. This new architecture exploits in a better way the redundancy and complementarity of the three muon subsystems: Cathode Strip Chambers (CSC), Drift Tubes (DT) and Resistive Plate Chambers (RPC). The role of each subsystem in the Level-1 Muon Trigger is described here, highlighting the contribution from the RPC system. Challenges brought by the HL-LHC environment and new possibilities coming from detector and trigger upgrades are also discussed

Research and development of the back-end electronics for the two-dimensional improved resistive plate chambers in CMS upgrade

International audienceTo complement and ensure redundancy in the endcap muon system of the Compact Muon Solenoid (CMS) detector and to extend the Resistive Plate Chamber (RPC) system coverage, improved RPCs (iRPCs) with either orthogonal layer strips with one-end electronics or single layer strips with two-end electronics providing more precise time measurement will be installed in the very forward pseudorapidity region of $|\eta |<2.4$. The iRPC readout system needs to support two-dimensional (2D) or two-end readout. In addition, it must combine detector data with Timing, Trigger and fast Control (TTC) and Slow Control (SC) into one data stream over a bi-directional optical link with a line rate of 4.8 Gb/s between the Front-End Electronics (FEE) and the Back-End Electronics (BEE). To fulfill these requirements, a prototype BEE for the iRPC 2D chamber has been researched and designed.A Micro-Telecommunication and Computing Architecture ($\mu$TCA)-based processing card was designed in this study to establish a prototype system together with a $\mu$TCA crate. The Giga-Bit Transceiver (GBT) protocol is integrated to provide bi-directional communication between the FEE and BEE. A server is connected with the BEE by a Gigabit Ethernet (GbE) link for SC and a 10-GbE link for Data AcQuisition (DAQ).The Bit Error Rate (BER) test of the back-end board and a joint test with the iRPC 2D prototype chamber were performed. A BER of less than $1.331\times {10^{-16}}$ was obtained. The time measurement with a resolution of 3.05 ns was successfully realized, and detector efficiencies of 97.7% for longitudinal strips and 96.0% for orthogonal strips were measured. Test results demonstrate the correctness and reliability of the prototype BEE.The BEE prototype satisfies the requirements for the iRPC 2D chamber, and it worked stably and reliably during a long-term joint test run

CMS RPC background — studies and measurements

International audienceThe expected radiation background in the CMS RPC system has been studied using the MC prediction with the CMS FLUKA simulation of the detector and the cavern. The MC geometry used in the analysis describes very accurately the present RPC system but still does not include the complete description of the RPC upgrade region with pseudorapidity 1.9 < |η| < 2.4. Present results will be updated with the final geometry description, once it is available. The radiation background has been studied in terms of expected particle rates, absorbed dose and fluence. Two High Luminosity LHC (HL-LHC) scenarios have been investigated — after collecting 3000 and 4000 fb-1. Estimations with safety factor of 3 have been considered, as well