Design, prototyping, and construction of the CMS Outer Tracker for the Phase-2 Upgrade

Due to the High Luminosity-Large Hadron Collider (HL-LHC) upgrade, several detectors of the Compact Muon Solenoid (CMS) will need to be upgraded, specifically the new Outer Tracker detector that will be composed of 13,200 silicon modules. The Outer Tracker features two types of modules; the PS (pixel-strip) and the 2S (strip-strip) modules. With a large influx of production of modules, extensive testing is required to ensure they fulfill the performance requirements. This research introduces POTATO (Phase-II Outer Tracker Analyzer of Test Outputs), a specialized software developed in C++ to analyze, grade, and store results in a centralized database since module data will be collected from various international production facilities. The implementation of POTATO will facilitate the selection of the best performing modules for the Outer Tracker upgrade. This paper is focused on the implementation of the analysis of 2S Module results within POTATO.

The LHC machine is planning an upgrade program which will smoothly bring the instantaneous luminosity to about $\mathrm{5 - 7.5 \times 10^{34} cm^{-2}s^{-1}}$ in 2028, to reach an integrated luminosity of $\mathrm{3000 \ fb ^{-1}}$ and possibly up to $\mathrm{4500 \ fb ^{-1}}$ by the end of 2039. This High Luminosity LHC scenario, HL-LHC, will require an upgrade program of the LHC detectors known as Phase-2 upgrade. The current CMS Outer Tracker, already running beyond design specifications, and CMS Pixel Detector will not be able to survive HL-LHC radiation conditions and CMS will need completely new devices, in order to fully exploit the highly demanding conditions and the delivered luminosity. The new Outer Tracker should also have trigger capabilities. To achieve such goals, R&D activities have explored options for both the Outer Tracker and for the Inner Tracker. The solutions developed will allow to include tracking information in the first trigger stage. The design choices for the Tracker upgrades are discussed along with some highlights on technological approaches and R&D activities.

Process quality control strategy for the Phase-2 Upgrade of the CMS Outer Tracker and High Granularity Calorimeter

Radiation testing of electronics for the CMS endcap muon system

The Outer Tracker detector of the Compact Muon Solenoid (CMS) experiment provides information about the trajectory of charged particles produced in proton-proton collisions at the Large Hadron Collider (LHC). During the High Luminosity LHC upgrade, scheduled for the late 2020s, the Outer Tracker will be replaced with new modules capable of transmitting data to the L1 Trigger. These modules are being assembled at several facilities around the world, including Fermilab, necessitating coordinated standards of module quality. Here I discuss the development of POTATO (Phase-II Outer Tracker Analyzer of Test Outputs), a C++ software which provides a standardized procedure for analyzing and grading test results of the Outer Tracker modules. The particular focus of this paper is on the analysis and grading of the PS (pixel-strip) modules in POTATO.

The LHC machine is planning an upgrade program which will smoothly bring the luminosity to about 5 $\times$ $10^{34} $cm$^{-2}$s$^{-1}$ in 2028, to possibly reach an integrated luminosity of 3000 fb$^{-1}$ by the end of 2037. This High Luminosity LHC scenario, HL-LHC, will require a preparation program of the LHC detectors known as Phase-2 upgrade. The current CMS Outer Tracker, already running beyond design specifications, and CMS Phase-1 Pixel Detector will not be able to survive HL-LHC radiation conditions and CMS will need completely new devices, in order to fully exploit the high-demanding operating conditions and the delivered luminosity. The new Outer Tracker should have also trigger capabilities. To achieve such goals, R$\&$D activities are ongoing to explore options both for the Outer Tracker, and for the pixel Inner Tracker. Solutions are being developed that would allow including tracking information at Level-1. The design choices for the Tracker upgrades are discussed along with some highlights of the R$\&$D activities.

This thesis presents two research works carried out within the Compact Muon Solenoid (CMS) experiment at the CERN Large Hadron Collider (LHC): the system validation of the scintillator section of the High Granularity Calorimeter (HGCAL), and a search for a heavy resonance coupling to top quarks and produced in association with top quark pairs in proton–proton collisions at center-of-mass energies of 13 and 13.6 TeV. For the High-Luminosity LHC (HL-LHC) phase, the endcap calorimeters of CMS will be replaced by the HGCAL, a high-precision sampling calorimeter designed to cope with the extreme radiation and pileup conditions expected at the HL-LHC. In regions where radiation levels remain moderate, the hadronic section employs scintillator tiles coupled to silicon photomultipliers (SiPM-on-tile) as active materials. Each HGCAL tilemodule, the basic detector unit of this region, accommodates up to 144 SiPM-on-tile channels read out by dedicated front-end electronics. The performance of several tilemodules was evaluated during test-beam campaigns at the DESY-II facility using 3 GeV electron beams. The measurements serve to validate the response and uniformity of the detector components and to confirm that they meet the design specifications for HL-LHC operation. A search for a new heavy resonance that couples exclusively to top quarks and is produced in association with a top quark pair is presented. The analysis uses proton–proton collision data collected with the CMS detector at center-of-mass energies of 13 TeV (2016–2018) and 13.6 TeV (2022). The search targets the final state with two oppositely charged leptons from the W boson decays of the nonresonant top quarks, and two high-energy jets reconstructing the hadronically decaying resonant top quarks. In this scenario, the two top quarks from the resonance decay are expected to be highly Lorentz-boosted. Their hadronic decays are reconstructed using jets clustered with a variable-radius algorithm and identified with a dedicated top quark tagger based on a boosted decision tree (BDT). Events are selected in a final state containing opposite-sign leptons and b-tagged jets, and the resonance mass is reconstructed from pairs of tagged top jets. The analysis probes resonance masses between 500 GeV and 4 TeV and searches for local excesses in the reconstructed mass spectrum. The results are interpreted in the context of models with vector-like, scalar and pseudoscalar resonances produced in association with top quarks, representing the first such interpretation performed with CMS data.

The ATLAS detector was designed and built to study proton-proton collisions produced at the LHC at centre-of-mass energies up to 14 TeV and instantaneous luminosities up to $10^{34} cm^{-2} s^{-1}$. A Liquid Argon-lead sampling (LAr) calorimeter is employed as electromagnetic and hadronic calorimeters, except in the barrel region, where a scintillator-steel sampling calorimeter (TileCal) is used as hadronic calorimeter. This presentation gives first an overview of the detector operation and data quality, as well as of the achieved performances of the ATLAS calorimetry system. Additionally the upgrade projects of the ATLAS calorimeter system for the high luminosity phase of the LHC (HL-LHC) are presented. For the HL-LHC, the instantaneous luminosity is expected to increase up to $L \\simeq 7.5 × 10^{34} cm^{-2} s^{-1}$ and the average pile-up up to 200 interactions per bunch crossing. The major R&D item is the upgrade of the electronics for both LAr and Tile calorimeters in order to cope with longer latencies of up to 60 ${\\mu}s$. The expected radiation doses will exceed the qualification range of the current readout system. The status of the R&D of the low-power ASICs (pre-amplifier, shaper, ADC, serializer and transmitters) and readout electronics for all the design options is discussed. Moreover, a High Granularity Timing Detector (HGTD) is proposed to be added in front of the LAr calorimeters in the end-cap region (2.4 <|$\\eta$|< 4.2) for pile-up mitigation at Level-0 trigger level and offline reconstruction. The HGTD will correlate the energy deposits in the calorimeter to different proton-proton collision vertices by using TOF information with high time resolution (30 pico-seconds per readout cell) based on the Silicon sensor technologies. The current test beam results are presented in this document as well.

The Compact Muon Solenoid (CMS) detector at the European Council for Nuclear Research (CERN) Large Hadron Collider (LHC) is undergoing an extensive Phase II upgrade program to prepare for the challenging conditions of the high-luminosity LHC (HL-LHC). In particular, a new timing layer will measure minimum ionizing particles (MIPs) with a time resolution of ~30–40 ps and hermetic coverage up to a pseudorapidity of $\left |{ \eta }\right |=3$ . The precision time information from this detector will reduce the effects of the high levels of pileup expected at the HL-LHC and will bring new and unique capabilities to the CMS detector. This MIP Timing Detector (MTD) will consist of a central barrel timing layer (BTL) based on L(Y)SO:Ce crystals read out with silicon photomultipliers (SiPMs) and two end-caps instrumented with radiation-tolerant low-gain avalanche detectors (LGADs). With the goal of maximizing the detector performance within the stringent constraints of space, cost, and channel count, the BTL exploits elongated crystal bars, each read out with two SiPMs. This unusual geometry enables the instrumentation of large surfaces while minimizing the active area of the photodetectors and thus noise and power consumption. This article presents a summary of the research and development studies carried out to optimize this crystal-based technology and key beam test results in which the target time resolution of 30 ps has been achieved.

A new tracking detector will be installed as part of the Phase-2 upgrade of the CMS detector for the high-luminosity LHC era. This tracking detector includes the Inner Tracker, equipped with silicon pixel sensor modules, and the Outer Tracker, consisting of modules with two parallel stacked silicon sensors. The Outer Tracker front-end ASICs will be able to correlate hits from charged particles in these two sensors to perform on-module discrimination of transverse momenta (p T). The p T information is generated at a frequency of 40 MHz and will be used in the Level-1 trigger decision of CMS. Prototypes of the so-called 2S modules were tested at the Test Beam Facility at DESY Hamburg between 2019 and 2020. These modules use the final front-end ASIC, the CMS Binary Chip (CBC), and for the first time the Concentrator Integrated Circuit (CIC), optical readout and on-module power conversion. In total, seven modules were tested, one of which was assembled with sensors irradiated with protons. An important aspect was to show that it is possible to read out modules synchronously. A cluster hit efficiency of about 99.75 % was achieved for all modules. The CBC p T discrimination mechanism has been verified to work together with the CIC and optical readout. The measured module performance meets the requirements for operation in the upgraded CMS tracking detector.

The Compact Muon Solenoid (CMS) experiment at CERN is scheduled for a major upgrade in the next decade in order to meet the demands of the new High Luminosity Large Hadron Collider. Amongst others, a new tracking system is under development including an outer tracker capable of rejecting low transverse momentum particles by looking at the coincidences of hits (stubs) in two closely spaced sensor layers in the same tracker module. Accepted stubs are transmitted off-detector for further processing at 40 MHz. In order to maintain under the increased luminosity the Level-1 trigger rate at 750 kHz, tracker data need to be included in the decision making process. For this purpose, a system architecture has to be developed that will be able to identify particles with transverse momentum above 3 GeV/c by building tracks out of stubs, while achieving an overall processing latency of maximum 4us. Targeting these requirements the current paper presents an FPGA-based track finding architecture that identifies track candidates in real-time and bases its functionality on a fully time-multiplexed approach. As a proof of concept, a hardware system has been assembled targeting the MP7 MicroTCA processing card that features a Xilinx Virtex-7 FPGA, demonstrating a realistic slice of the track finder. The paper discusses the algorithms' implementation and the efficient utilisation of the available FPGA resources, it outlines the system architecture, and presents some of the hardware demonstrator results.

The rich physics program at the high luminosity LHC (HL-LHC) requires all final state particles to be reconstructed with good accuracy. However, it also poses formidable challenge of dealing with very high pileup. Different identification algorithms need to be upgraded along with the detectors to improve the overall event reconstruction in such a hostile collision environment. The new timing device in the proposed CMS detector at the HL-LHC allows for the construction of timing observables at the track-level as well as at the jet-level. This information when given as inputs to the deep neural networks, have a potential to improve the existing algorithms used for heavy flavor (HF) jet tagging. In this paper, the latest developments on the studies for HF jet tagging performance at the HL-LHC are presented.

For the High Luminosity LHC, the Beam Radiation Instrumentation and Luminosity (BRIL) project will employ CMS tracker modules for precision luminosity measurement with an ambitious target offline luminosity precision of $1\%$. Inner tracker endcap (TEPX) luminosity will be based on the online clustering algorithm. An FPGA-based clustering algorithm has been developed to count hit clusters detected by RD53B readout chips. Simulations and beam tests have been conducted to validate the algorithm under realistic conditions. Disk 4 Ring 1 (D4R1) of the TEPX will be fully dedicated to luminosity, while the rest of TEPX will allocate $10\%$ of the trigger rate for luminosity. The Outer Tracker (OT) system will be utilized for high-statistics online luminosity measurements by providing high-rate physics objects known as Level-1 (L1) track stubs. Stubs are formed by detecting two-hit coincidences on closely spaced silicon sensors using front-end ASICs and are transmitted at a frequency of 40 MHz to the L1 track reconstruction system. For luminosity measurement, stubs will be aggregated in the histogramming firmware block. Currently, common mode noise within OT modules is being studied to evaluate its impact on the luminosity measurement using comparisons between a toy strip-strip (2S) module simulation and noise data from real 2S production modules.

The ATLAS experiment at CERN has started the construction of upgrades for the High Luminosity LHC (HL-LHC), with collisions due to start in 2026. In order to deliver an order of magnitude more data than previous LHC runs, 7 TeV protons will collide at 14 TeV with an instantaneous luminosity of up to $7.5 \cdot 10^{34}\;\text{cm}^{-2}\text{s}^{-1}$, resulting in much higher pileup and data rates than the current experiment was designed to handle. While this is essential to realise the physics program, it presents a huge challenge for the detector, trigger, data acquisition and computing. The detector upgrades themselves present new requirements and opportunities for the trigger and data acquisition system. The approved baseline design of the TDAQ upgrade comprises: a hardware-based low-latency real-time trigger operating at 40 MHz, data acquisition which combines custom readout with commodity hardware and networking to deal with 5.2 TB/s input, and an event filter running at 1 MHz, which combines offline-like algorithms on a large set of commodity servers and hardware tracking. Commodity servers and networks are used, with custom ATCA boards, high speed links and powerful FPGAs deployed in the low-latency parts of the system. Offline-style clustering and jet-finding in FPGAs, and track reconstruction with Associative Memory ASICs and FPGAs are designed to combat pileup in the hardware trigger and the event filter respectively. This document reports recent progress on the design of the system and the performance on key physics processes.

High-Luminosity Large Hadron Collider (HL-LHC) upgrade aims to increase performance. In order to efficiently handle the larger particle flux and increased radiation, an upgrade is planned for the inner Tracker of the Compact Muon Solenoid (CMS) detector, which is located at the innermost part of the CMS. To efficiently reconstruct and track particles, the existing pixel tracker will be upgraded with novel sensors, readout chips, and front-end electronics designed to handle increased data rates. These improvements will allow the detector to track particles more precisely. In the United States, we are working on assembling new sensor modules to be inserted into disks, referred to as TFPX, for installation in the CMS detector for the HL-LHC era. We are currently testing the prototype of TFPX modules to ensure the upgrade is carried out in the best way possible. The University of Ilinois Chicago has been tasked with testing the final versions of the TFPX sensor modules before they are sent to CERN to be installed into the CMS detector. This work is supported by NSF.