Ismail Okan Atakisi

Abstract The upgrade of the CMS experiment for the high luminosity operation of the LHC comprises the replacement of the current endcap calorimeter by a high granularity sampling calorimeter (HGCAL). The electromagnetic section of the HGCAL is based on silicon sensors interspersed between lead and copper (or copper tungsten) absorbers. The hadronic section uses layers of stainless steel as an absorbing medium and silicon sensors as an active medium in the regions of high radiation exposure, and scintillator tiles directly read out by silicon photomultipliers in the remaining regions. As part of the development of the detector and its readout electronic components, a section of a silicon-based HGCAL prototype detector along with a section of the CALICE AHCAL prototype was exposed to muons, electrons and charged pions in beam test experiments at the H2 beamline at the CERN SPS in October 2018. The AHCAL uses the same technology as foreseen for the HGCAL but with much finer longitudinal segmentation. The performance of the calorimeters in terms of energy response and resolution, longitudinal and transverse shower profiles is studied using negatively charged pions, and is compared to GEANT4 predictions. This is the first report summarizing results of hadronic showers measured by the HGCAL prototype using beam test data.

Abstract The Compact Muon Solenoid collaboration is designing a new high-granularity endcap calorimeter, HGCAL, to be installed later this decade. As part of this development work, a prototype system was built, with an electromagnetic section consisting of 14 double-sided structures, providing 28 sampling layers. Each sampling layer has an hexagonal module, where a multipad large-area silicon sensor is glued between an electronics circuit board and a metal baseplate. The sensor pads of approximately 1.1 cm 2 are wire-bonded to the circuit board and are readout by custom integrated circuits. The prototype was extensively tested with beams at CERN's Super Proton Synchrotron in 2018. Based on the data collected with beams of positrons, with energies ranging from 20 to 300 GeV, measurements of the energy resolution and linearity, the position and angular resolutions, and the shower shapes are presented and compared to a detailed Geant4 simulation.

Abstract We present the preliminary test results of the prototype detector, working at Sphinx Observatory Center, Jungfraujoch (~3800 m a.s.l.) HFSJG – Switzerland. This prototype detector is designed to measure large zenith angle showers produced by high energy neutrino interactions in the Earth crust. This station provides us an opportunity to understand if the prototype detector works safely (or not) under hard environmental conditions (the air temperature changes between −25 °C and −5 °C). The detector prototype is using silicon photomultiplier (SiPM) produced by SensL and DRS4 chip as read-out part. Measurements at different temperature at fixed bias voltage (~29.5 V) were performed to reconstruct tracks by Time Of Flight.

As part of its HL-LHC upgrade program, the CMS collaboration is replacing its existing endcap calorimeters with a high-granularity calorimeter (CE). The new calorimeter is a sampling calorimeter with unprecedented transverse and longitudinal readout for both electromagnetic and hadronic compartments. Due to its compactness, intrinsic time resolution, and radiation hardness, silicon has been chosen as active material for the regions exposed to higher radiation levels. The silicon sensors are fabricated as 20 cm (8") wide hexagonal wafers and are segmented into several hundred pads which are read out individually. As part of the sensor qualification strategy, 8" sensor irradiation with neutrons has been conducted at the Rhode Island Nuclear Science Center (RINSC) and followed by their electrical characterisation in 2020-21. The completion of this important milestone in the CE's R&D program is documented in this paper and it provides detailed account of the associated infrastructure and procedures. The results on the electrical properties of the irradiated CE silicon sensors are presented.

In preparation for collecting proton-proton collisions from the LHC at a center-of-mass energy of 13 TeV and rate of 40MHz with increasing instantaneous luminosity, the CMS collaboration prepared an array of triggers utilizing jets and missing transverse energy for searches for new physics at the energy frontier as well as for SM precision measurements. The CMS trigger system must be able to sift through the collision events in order to extract events of interest at a rate of 1kHz, applying sophisticated algorithms adapted for fast and effective operation. Particularly important is the calibration of the trigger objects, as corrections to the measured energy may be substantial. Equally important is the development of improved reconstruction algorithms to mitigate negative effects due to high numbers of overlapping proton-proton collisions and increased levels of beam-related effects. Work by the CMS collaboration on upgrading the high-level trigger for jets and missing transverse energy for the upgraded LHC operation will be presented, along with the improved performance of these triggers.