System Validation of the SiPM-on-Tile Section of the CMS High Granularity Calorimeter

Calorimetry at the High Luminosity Large Hadron Collider (HL-LHC), especially in the forward regions, encounters two significant challenges: to cope with high radiation levels and manage an unprecedented number of simultaneous events. To address these issues, the CMS Collaboration is planning to replace the endcap calorimeters with a high-granularity calorimeter (HGCAL). This innovative sampling calorimeter uses as active materials silicon sensors and scintillator tiles, which are read out by silicon photomultipliers (SiPMs). The fundamental component of the SiPM-on-tile system is the tile module, which includes a printed circuit board (PCB) equipped with one or two HGCROC ASICs, capable of reading a high number of SiPMs. The tile modules have been studied at the DESY-II test beam and undergone various laboratory trials. The production of the tile modules for the upgrade is scheduled to commence next year. This presentation presents the current status and plans for future production of the SiPM-on-tile region of the CMS HGCAL

Scintillator Section of the CMS High Granularity Calorimeter Upgrade (HGCAL)

For the HL-LHC phase, the calorimeter endcap of the CMS detector will be upgraded with a High Granularity Calorimeter (HGCAL), a sampling calorimeter that will use silicon sensors as well as scintillator tiles read out by silicon photomultipliers (SiPMs) as active material (SiPM-on-tile). The design of the SiPM-on-tile section was inspired by the CALICE AHCAL. The complete HGCAL will be operated at -30°C.The basic detector unit in the SiPM-on-tile section is the tile module, consisting of a PCB with one or two HGCROC ASICs, reading out up to 96 SiPM-on-tiles. For geometric reasons, the tile modules and the tiles on the tile modules will increase in size with increasing radial distance from the beam pipe. Eight variations of tile modules have been designed to cover the full area of 340 m². This includes the use of two different SiPM sizes and 21 different tile sizes manufactured using two different materials.Tests on tile modules have been conducted at beam tests at DESY-II and CERN SPS and in lab experiments including using climate chambers operating at -30°C. Production of tile modules for the upgrade is foreseen to start next year. An overview of the current status and production plans of the SiPM-on-tile section will be presented in this poster

Multi-Tilemodule test system using cosmic rays for the CMS HGCAL upgrade - Status of the cosmic test stand for Tilemodule quality control at DESY

The CMS experiment plans to upgrade its calorimeter endcap for the high luminosity phase of the LHC with the High Granularity Calorimeter (HGCAL). The Tilemodule is one of the basic elements in the hadronic calorimeter part of the HGCAL. It uses small scintillator tiles directly coupled to SiPMs (SiPM-on-tile technology) and it is the first step in the production sequence providing an object capable of detecting particles. The Tilemodule is equipped with one or two HGCROC ASICs for data readout. To test and calibrate the Tilemodules, a cosmic ray setup capable of testing up to 9 Tilemodules simultaneously is developed for quality control and a better understanding of the property of the Tilemodules. The presentation will discuss the idea and current status of the cosmic test setup at DESY

SiPM-on-Tile Technology for the Phase II upgrade of the CMS High Granularity Endcap Calorimeter (HGCAL)

The CMS Collaboration is preparing to replace its endcap calorimeters for the HL-LHC era with a high-granularity calorimeter (HGCAL). The HGCAL will have fine segmentation in both the transverse and longitudinal directions, and will be the first such imaging calorimeter specifically optimized for particle-flow reconstruction to operate at a colliding-beam experiment. It is a sampling calorimeter that will use silicon sensors as well as scintillator tiles read out by silicon photomultipliers (SiPMs) as the active material. The HGCAL will be operated at -30° C. The SiPMs will be used in areas where the expected radiation dose during the lifetime of the detector is up to 5x10¹³ n/cm².The technology consisting of scintillator tiles of a few centimetre lengths read out individually by SiPMs, is known as the SiPM-on-tile technology. The basic detector unit in the SiPM-on-tile part is the tileboard consisting of a PCB with one or two HGCROC ASICs, SiPMs, scintillators and other onboard electronic systems. These modules have undergone beam tests at DESY II, investigating the interplay of the components and evaluating the performance with several types of the scintillator tiles and SiPM sizes. This poster will give an overview on of the SiPM-on-tile technology and report on these beam tests

Using graph neural networks to reconstruct charged pion showers in the CMS High Granularity Calorimeter

A novel method to reconstruct the energy of hadronic showers in the CMS High Granularity Calorimeter (HGCAL) is presented. The HGCAL is a sampling calorimeter with very fine transverse and longitudinal granularity. The active media are silicon sensors and scintillator tiles readout by SiPMs and the absorbers are a combination of lead and Cu/CuW in the electromagnetic section, and steel in the hadronic section. The shower reconstruction method is based on graph neural networks and it makes use of a dynamic reduction network architecture. It is shown that the algorithm is able to capture and mitigate the main effects that normally hinder the reconstruction of hadronic showers using classical reconstruction methods, by compensating for fluctuations in the multiplicity, energy, and spatial distributions of the shower's constituents. The performance of the algorithm is evaluated using test beam data collected in 2018 prototype of the CMS HGCAL accompanied by a section of the CALICE AHCAL prototype. The capability of the method to mitigate the impact of energy leakage from the calorimeter is also demonstrated.Peer reviewe

Response of a CMS HGCAL silicon-pad electromagnetic calorimeter prototype to 20-300 GeV positrons

CMS 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 extensively tested with beams at CERN's SPS in 2018. The electromagnetic section of the detector called CE-E prototype, consists of 14 double-sided structures, providing 28 sampling layers. Each layer carries a hexagonal module where a multi-pad large area silicon sensor is glued between the electronics PCB and a metal baseplate. The sensor pads of approximately 1 cm$^2$ are wire-bonded to the PCB and are readout by the Skiroc2-CMS ASIC. The prototype has been exposed to beams of positrons with energies ranging from 20 to 300 GeV. Based on these data, measurements of the CE-E prototype energy resolution and linearity, position resolution, resolution on the positron angle of incidence derived from the shower axis reconstruction and shower shapes are presented and compared to detailed GEANT4 simulations

Timing performance of the CMS High Granularity Calorimeter prototype

This paper describes the experience with the calibration,reconstruction and evaluation of the timing capabilities of the CMSHGCAL prototype in the beam tests in 2018. The calibrationprocedure includes multiple steps and corrections ranging from tensof nanoseconds to a few hundred picoseconds. The timing performanceis studied using signals from positron beam particles with energiesbetween 20 GeV and 300 GeV. The performance is studied as afunction of particle energy against an external timing reference aswell as standalone by comparing the two different halves of theprototype. The timing resolution is found to be 60 ps forsingle-channel measurements and better than 20 ps for full showersat the highest energies, setting excellent perspectives for theHGCAL calorimeter performance at the HL-LHC

Timing Performance of the CMS High Granularity Calorimeter Prototype

This paper describes the experience with the calibration, reconstruction and evaluation of the timing capabilities of the CMS HGCAL prototype in the beam tests in 2018. The calibration procedure includes multiple steps and corrections ranging from tens of nanoseconds to a few hundred picoseconds. The timing performance is studied using signals from positron beam particles with energies between 20 GeV and 300 GeV. The performance is studied as a function of particle energy against an external timing reference as well as standalone by comparing the two different halves of the prototype. The timing resolution is found to be 60 ps for single-channel measurements and better than 20 ps for full showers at the highest energies, setting excellent perspectives for the HGCAL calorimeter performance at the HL-LHC

Response of a CMS HGCAL silicon-pad electromagnetic calorimeter prototype to 20–300 GeV positrons

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

Neutron irradiation and electrical characterisation of the first 8” silicon pad sensor prototypes for the CMS calorimeter endcap upgrade

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