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Quality concerns caused by quality control — deformation of silicon strip detector modules in thermal cycling tests

The ATLAS experiment at the Large Hadron Collider (LHC) is currently preparing to replace its present Inner Detector (ID) with the upgraded, all-silicon Inner Tracker (ITk) for its High-Luminosity upgrade (HL-LHC). The ITk will consist of a central pixel tracker and the outer strip tracker, consisting of about 19,000 strip detector modules. Each strip module is assembled from up to two sensors, and up to five flexes (depending on its geometry) in a series of gluing, wirebonding and quality control steps. During detector operation, modules will be cooled down to temperatures of about -35 °C (corresponding to the temperature of the support structures on which they will be mounted) after being initially assembled and stored at room temperature. In order to ensure compatibility with the detector's operating temperature range, modules are subjected to thermal cycling as part of their quality control process. Ten cycles between -35 °C and +40 °C are performed for each module, with full electrical characterisation tests at each high and low temperature point. As part of an investigation into the stress experienced by modules during cooling, it was observed that modules generally showed a change in module shape before and after thermal cycling. This paper presents a summary of the discovery and understanding of the observed changes, connecting them with excess module stress, as well as the resulting modifications to the module thermal cycling procedure.

47 OTHER INSTRUMENTATION↗

Combination of searches for nonresonant Higgs boson pair production in proton–proton collisions at $\sqrt{s}$ = 13 TeV

This paper presents a combination of searches for the nonresonant production of Higgs boson pairs (HH) in proton–proton collisions at a centre-of-mass energy of 13 TeV. The dataset was collected by the CMS experiment at the LHC from 2016 to 2018 and corresponds to a total integrated luminosity of 138 fb –1 . The observed (expected) upper limit on the inclusive HH production cross-section relative to the standard model (SM) prediction is found to be 3.5 (2.5). Assuming all other Higgs boson couplings are equal to their SM values, the Higgs boson trilinear self-coupling modifier κ λ = λ 3 /λ$^{SM}_{3}$ is constrained in the range –1.35 ≤ κ λ ≤ 6.37 at 95% confidence level (CL). Similarly, for the coupling modifier κ 2V , which governs the interactions between two vector bosons and two Higgs bosons, we have excluded κ 2V = 0 at more than five standard deviations for all values of κ λ . At 95% CL, assuming that the other couplings are equal to their SM values, κ 2V is constrained in the range 0.64 ≤ κ 2V ≤ 1.40. This work also investigates HH production in several new physics scenarios, using the Higgs effective field theory (HEFT) framework. The HEFT framework is further exploited to study various ultraviolet complete models with an extended Higgs sector and set constraints on specific parameters. An extrapolation of the results in the expected integrated luminosity following the high-luminosity upgrade of the LHC is also reported.

BSM↗

Ultra-low magnetization and hysteresis loss in APC Nb 3 Sn superconductors

For the accelerator magnets of the next hadron collider, reducing superconductor persistent-current magnetization is not only important for achieving the desired field quality, but also crucial for its sustainability because the magnetization loss is the major heat load to the magnet cold mass. For conventional Nb 3 Sn conductors this requires reduction of effective subelement size (D eff ). For the restacked-rod-process (RRP ® ) conductors a physical subelement size (D sub ) as small as 35 µm (corresponding to a D eff close to 45 µm) can be reached, but at a significant price in J c . Another way to reduce the magnetization is by introducing artificial pinning centers (APC) using the internal oxidation approach. APC conductors outperform conventional Nb 3 Sn wires in two aspects: 1) higher J c at high fields, and 2) much lower J c and magnetization at low fields (e.g. below 5 T). Here, in this work we explored the fabricability of APC wires with small D sub . A 180-stack APC wire was produced and drawn to 0.7- and 0.5 mm diameters with good quality, with D sub s of 34 and 24 µm (D eff s of 36 and 25 µm), respectively. For the 34 µm-D sub wire, its non-Cu J c is higher than that of an RRP ® wire used for the High-Luminosity Large Hadron Collider (HL-LHC) project above 13 T (e.g. 36% higher at 4.2 K, 18 T), while its non-Cu magnetization at 1 T, ΔM(1 T), is only 29% of the RRP ® wire. Its non-Cu hysteresis loss for a cycle between 1 and 14 T, Q h (1–14 T), is 37% of the RRP ® wire. For the 24 µm-D sub wire, its non-Cu J c surpasses the HL-LHC RRP ® wire above 17.5 T, while its ΔM(1 T) and Q h (1–14 T) are only 17% and 23% of the RRP® wire, respectively. Its non-Cu Q h (±3 T) even meets the specification of the International Thermonuclear Experimental Reactor project.

Xu, X [Fermi National Accelerator Laboratory (FNAL↗

CMS Endcap Timing Layer: System Validation and Assembly

The High-Luminosity Large Hadron Collider (HL-LHC) will operate at unprecedented luminosities, resulting in up to 200 simultaneous interactions per bunch crossing. To mitigate the resulting pileup challenges, the CMS experiment is implementing the MIP Timing Detector (MTD), designed to provide precise timing information with a resolution of 30 – 40 picoseconds per track. The MTD consists of the Barrel Timing Layer (BTL) and the Endcap Timing Layer (ETL), each optimized for different regions of the detector. The ETL, comprising two double-sided disks, utilizes Low-Gain Avalanche Diode (LGAD) sensors coupled with the Endcap Timing Readout Chip (ETROC) to achieve high-precision timing measurements in the forward region. Significant progress has been made toward the realization of the ETL through extensive system-level validation of the ETROC readout chain and the development of scalable module assembly procedures. This presentation will provide a comprehensive overview of the ETL and highlight recent advances in system validation and module assembly, emphasizing their roles in ensuring the detector readiness for HL-LHC operation.

Lee, Dongyub [Kyungpook Natl. U.] (ORCID:000000034↗

Pixel-Strip Module Testing and Performance Analysis for the CMS Phase-2 Outer Tracker Upgrade

In response to the demanding environment of the High-Luminosity Large Hadron Collider (HL-LHC), the Compact Muon Solenoid (CMS) Experiment's Outer Tracker is being replaced with a lighter, higher-granularity, radiation-tolerant silicon detector capable of providing tracking information directly to the Level-1 trigger system. The new Outer Tracker consists of Pixel-Strip (PS) and Strip-Strip (2S) transverse momentum (pT) modules, which are assembled and tested at, among other centers, Fermilab's Silicon Detector Facility. PS modules consist of a pixel sensor, a strip sensor, and multiple application-specific integrated circuits (ASICs). This poster studies the performance of MaPSAs, silicon macro-pixel sensors bump-bonded to 16 macro-pixel ASICS. It presents the testing procedures for MaPSAs and MaPSA-strip sensor sub-assemblies, as well as the results of calibration and performance studies of two PS modules before and after irradiation. These results assess the impact of irradiation on module performance, providing insight into the modules' expected performance in the HL-LHC environment.

Kimrey, Emerson [Scripps College]↗

Investigation and Diagnosis of Faulty Data Channels in CMS Outer Tracker Module Testing

The High-Luminosity Large Hadron Collider (HL-LHC) is currently undergoing upgrades to improve its luminosity. In parallel, this requires an upgrade to the Compact Muon Solenoid (CMS)’s Outer Tracker, consisting of Pixel-Strip (PS) and Strip-Strip (2S) modules that can accurately track the path of charged particles originating from the collisions. It follows that such complex modules call for extensive testing, requiring a sophisticated Data Acquisition (DAQ) system that can perform specific tests to assess their performance. In addition, errors caused by the hardware of a given testing station, and its associated data channel, need to be accurately identified to guarantee proper testing of modules. We have developed a software extension to the Phase-II Outer Tracker Analyzer of Test Outputs (POTATO), which is a specialized software designed to analyze and grade all of the module tests through a centralized database. This extension categorizes and analyzes module test results by its station and data channel. Its analysis can be used to identify trends in grading that indicate issues in these channels’ grading process rather than in the individual modules. This poster shows our methodology and results for identifying faulty data channels. Using this extension, we can quickly diagnose and address problems in our DAQ system, ensuring proper evaluation corrections for each module.

Chen, Angus [Fermilab]↗

Performance Validation of Endcap Timing Layer Detector Modules for CMS Phase-2 Upgrade

The High-Luminosity Large Hadron Collider (HL-LHC) will operate up to 200 simultaneous collisions per bunch crossing, which is a significant jump from the current value of about 30 collisions per bunch crossing, producing significant pileup that challenges accurate event reconstruction. To address this, the Compact Muon Solenoid (CMS) experiment is implementing the Endcap Timing Layer (ETL), a precision timing detector designed to provide timing measurements with a resolution of approximately 50 ps per hit and 35 ps per reconstructed track. This project focuses on the characterization and validation of ETL detector modules using laboratory laser test data. ETL performance is evaluated by analyzing key quantities such as Bunch Crossing Identification (BCID), Time-of-Arrival (TOA), Time-over-Threshold (TOT), Noise Stability etc. The resulting analysis provides insight into the timing performance and operational stability of ETL modules, contributing to the quality assurance process req uired before their installation in the CMS experiment and ensure that the modules can meet the long-term reliability requirements of approximately 10 years of operation without replacement.

Chipara, Munashe [Fermilab]↗

Investigation and Diagnosis of Faulty Data Channels in CMS Outer Tracker Module Testing

The High-Luminosity Large Hadron Collider (HL-LHC) is currently undergoing upgrades to improve its luminosity. In parallel, this requires an upgrade to the Compact Muon Solenoid (CMS)’s Outer Tracker, consisting of Pixel-Strip (PS) and Strip-Strip (2S) modules that can accurately track the path of charged particles originating from the collisions. It follows that such complex modules call for extensive testing, requiring a sophisticated Data Acquisition (DAQ) system that can perform specific tests to assess their performance. In addition, errors caused by the hardware of a given testing station, and its associated data channel, need to be accurately identified to guarantee proper testing of modules. We have developed a software extension to the Phase-II Outer Tracker Analyzer of Test Outputs (POTATO), which is a specialized software designed to analyze and grade all of the module tests through a centralized database. This extension categorizes and analyzes module test results by its station and data channel. Its analysis can be used to identify trends in grading that indicate issues in these channels’ grading process rather than in the individual modules. This poster shows our methodology and results for identifying faulty data channels. Using this extension, we can quickly diagnose and address problems in our DAQ system, ensuring proper evaluation corrections for each module.

Chen, Angus [Fermilab]↗

Assembly and Testing of Scintillator Tile Modules for the CMS High-Granularity Calorimeter Upgrade

The High-Granularity Calorimeter (HGCAL), part of the upgrade to the Compact Muon Solenoid (CMS) experiment, employs silicon and scintillator tile modules in the endcaps to maintain detector performance during the High-Luminosity Large Hadron Collider (HL-LHC) era, scheduled to operate from 2030 to 2040. The upgraded calorimeter will provide highly segmented three-dimensional imaging, energy measurements, and precise timing for particle shower reconstruction. Approximately half of the HGCal plastic scintillator tile modules (1,834 total) will be assembled at Fermilab using an automated pick-and-place (PnP) machine. Following assembly, each tile module undergoes quality control (QC) procedures such as electrical validation, thermal testing, and physics validation using cosmic rays. This poster/talk presents the QC procedures and results from the tile module production in 2026, demonstrating the performance and quality of the assembled tile modules.

Bazimya, Jean Luc [Grambling State U.]↗

Quality Control of Silicon Sensor Modules for Particle Detectors

The High-Luminosity Large Hadron Collider (HL-LHC) will produce a higher rate of particle collisions than the current Large Hadron Collider (LHC), requiring important upgrades to the Compact Muon Solenoid (CMS) to handle an increased amount of data. An important upgrade is the Phase-2 Outer Tracker Upgrade, which consists of 13,000 silicon sensor modules made of two parallel silicon sensors and readout electronics. These modules undergo careful quality control checks both during and after module assembly to ensure precise and reliable detector performance. This project focuses on precision testing for quality control of silicon sensor modules at Fermilab. Hands-on work includes visual inspection, current-voltage testing, module testing, and ultraviolet (UV) light exposure of modules showing abnormal current-voltage behavior. The ultraviolet exposure process improves the abnormal sensor readout data by placing the selected sensor side of the module directly under the UV light inside a controlled box. In addition to laboratory testing and ultraviolet experiments, I developed a Python-based data tool that connects to a module database and allows selected testing conditions and module information to be retrieved and displayed efficiently. These different testing procedures, experimental processes, and computational tools support the broader goal of identifying module issues and improving modules that will be used in the CMS Outer Tracker Phase-2 Upgrade.

Siddiqui, Hooriya [DuPage Coll.] (ORCID:0009000151↗

Quality Control of Silicon Sensor Modules for Particle Detectors

The High-Luminosity Large Hadron Collider (HL-LHC) will produce a higher rate of particle collisions than the current Large Hadron Collider (LHC), requiring significant upgrades to the Compact Muon Solenoid (CMS) to handle the increased amount of data. An important upgrade is the Phase-2 Outer Tracker Upgrade, which consists of 13,000 silicon sensor modules made of two parallel silicon sensors and readout electronics. These modules undergo careful quality control checks both during and after module assembly to ensure precise and reliable detector performance. This project focuses on precision testing for quality control of silicon sensor modules at Fermilab. Hands-on work includes visual inspection, current-voltage testing, module testing, and ultraviolet (UV) light exposure of modules showing abnormal current-voltage behavior. The ultraviolet exposure process improves the abnormal sensor readout data by placing the selected sensor side of the module directly under the UV light inside a controlled box. In addition to laboratory testing and ultraviolet experiments, I developed a Python-based data tool that connects to a module database and allows selected testing conditions and module information to be retrieved and displayed efficiently. These different testing procedures, experimental processes, and computational tools support the broader goal of identifying module issues and improving modules that will be used in the CMS Outer Tracker Phase-2 Upgrade.

Siddiqui, Hooriya [DuPage Coll.; Fermilab] (ORCID:↗

Neutrino Physics and Astrophysics at Colliders

Nonzero neutrino masses guarantee new physics and neutrinos are excellent probes of extreme environments in the Universe. The recent collider neutrino experimental program, including FASER$ν$ and SND@LHC, along with the planned Forward Physics Facility at the High-Luminosity Large Hadron Collider, is opening a new window into neutrino physics and astrophysics. In this article, we review recent achievements and prospects of collider neutrino experiments, including key achievements such as the first measurements of collider neutrino interactions at unprecedented energies and the exploration of new physics scenarios, like dark matter candidates, sterile neutrinos, and non-standard neutrino interactions. For concreteness, we will focus on the significant scientific opportunities presented by the Forward Physics Facility, which will enable precision measurements of neutrino cross sections and proton structure at low parton momentum fraction. Furthermore, collider neutrino studies will substantially reduce systematic uncertainties in calculating atmospheric neutrino fluxes, thereby improving astrophysical neutrino observations as well as advancing our understanding of cosmic-ray interactions.

Machado, Pedro [Fermilab] (ORCID:0000000291187354)↗

Phenomenology of electroweak portal dark showers: high energy direct probes and low energy complementarity

We investigate the phenomenology of a dark QCD sector interacting with the Standard Model (SM) via the electroweak (EW) portals. The portal interactions allow SM bosons, such as Z and h, or additional bosons that mix with them, to decay into dark quarks, producing dark showers. The light dark mesons are expected to be long-lived particles (LLPs), as their decays back to the SM states through the EW-portal interactions typically have macroscopic decay lengths. We focus on dark shower events initiated by various bosons at the Large Hadron Collider (LHC). The most prominent signal is the displaced decay of GeV-scale dark pions as LLPs. Current limits on dark shower signals at LHC detectors are recast from public data to provide simplified limits insensitive to UV physics details. Future limits in the high-luminosity phase and proposed auxiliary detectors are also projected. Additionally, we study the flavor-changing neutral current (FCNC) B decays into dark pions, obtaining both current and projected constraints at the LHC and other facilities. These constraints can be combined for specific models, which are illustrated in two EW-portal benchmarks: one with the heavy doublet fermion mediation and another with the Z′ mediator including a mass mixing. The collider reach shows significant potential to probe the parameter space unconstrained by EW precision tests, highlighting the necessity of dedicated LLP search strategies and facilities.

Dark Matter at Colliders↗

New opportunities for rare charm from $Z\rightarrow c\bar{c}$ decays

We analyze the potential of rare charm decays as probes of new physics at a high-luminosity flavor facility operating at the Z pole, such as the FCC-ee or CEPC. In particular, we identify clean null-test observables in $D^0 → π^+ π^- v\bar{v}$ and in polarized $Λ^+_c → p ℓ^+ ℓ^-$ decays with $ℓ = e, μ$. Complementarity with the LHC and HL-LHC flavor programs arises from the characteristic features of a Tera-Z environment: the capability to study missing-energy modes and charm production with significant polarization. We improve the theoretical description of $D^0 → π^+ π^- v\bar{v}$ decays and work out the phenomenology of polarization-induced null-test observables in $Λ^+_c → p ℓ^+ ℓ^-$ decays. In regions of dilepton mass near the φ resonance, polarization asymmetries can reach $O$(5%) for muons and $O$(14%) for electrons times the $Λ^+_c$ polarization. We also point out synergies between the dineutrino and the dilepton modes using the SMEFT framework of heavy new physics. Using the IDEA detector concept at FCC-ee, we find in simulation studies that dineutrino branching fractions as low as ~ 2 x 10 -7 can be probed, which reaches well into the parameter space of new physics, and also allows for discrimination of lepton flavor structures. Furthermore, the measurement of asymmetries in $Λ^+_c → p ℓ^+ ℓ^-$ at $O$(1%) will be possible. Similar sensitivities are expected for dielectron final states, although robust predictions will require further dedicated studies.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

A Radiation-Hard 8-Channel 15-Bit 40-MSPS ADC for the ATLAS Liquid Argon Calorimeter Readout

The custom design of a radiation-hardened, 8-channel, 40-MSPS, 15-bit resolution, 14.2-bit dynamic range, 11.4-ENOB ADC data acquisition ASIC fabricated in a commercial 65-nm triple-well CMOS technology is presented. The ADC is developed for and integrates seamlessly into the readout system for the ATLAS liquid argon (LAr) calorimeter in the high-luminosity large hadron collider (HLLHC) upgrade at CERN, which will require a total of 364 936 ADC channels. A three-stage MDAC+SAR pipelined ADC architecture was designed to meet the physics requirements and scientific goals of the ATLAS experiment. The ADC is a fully self-contained data acquisition system that includes foreground calibration, digital data processing, digital control, and supporting circuitry. The measured performance shows the ADC achieves a competitive dynamic range and SNDR, and it meets or exceeds the ATLAS analog requirements. Radiation tolerance and scalability design considerations were implemented at the device-, circuit-, and system-level. Radiation-hardening-by-design techniques used include redundancy for digital circuits, the use of MiM capacitors, and a hybrid RC-DAC for the ADC core. The ADC ASIC was demonstrated to be robust against the effects of the intense radiation expected in the HL-LHC experimental environment.

DAQ↗

High Multiplicity Trigger for long-lived particles in CMS detector

Searches for long-lived particles (LLPs) at the CMS experiment often involve unconventional event topologies that are difficult to efficiently select using standard trigger strategies. To improve sensitivity to such signatures during LHC Run 3 operation, a dedicated High Multiplicity Trigger (HMT) has been developed and deployed in the CMS trigger system. The trigger targets events containing unusually large numbers of hits in the CMS cathode strip chamber (CSC) muon detectors, a characteristic signature of several LLP scenarios involving displaced decays in the muon system. The HMT implementation, trigger logic, rate dependence with pileup, and operational stability are described. Optimized hit multiplicity thresholds are used to maintain acceptable trigger rates under high-luminosity and high-pileup conditions while preserving high efficiency across a broad range of LLP lifetimes and kinematic regimes. The trigger performance is evaluated using both simulated event samples and proton-proton collision data collected during Run 3 of the LHC. The HMT substantially extends the CMS sensitivity to non-standard signatures associated with LLP decays and provides a flexible platform for future searches for physics beyond the Standard Model.

47 OTHER INSTRUMENTATION↗

The Low-Beta Quadrupoles for the High-Luminosity Large Hadron Collider: enabling higher luminosity by using Nb_3Sn conductor

The large-aperture, high-gradient Low Beta Quadrupoles for the High Luminosity Large Hadron Collider at CERN are the cornerstones of this collider. They are first-of-the-kind accelerator magnets bringing Nb_3Sn conductor to High Energy Physics colliders. In the US they are being fabricated and tested by the HL-LHC Accelerator Upgrade Project (AUP), and in Europe by CERN. The design was developed by AUP and CERN in close collaboration. The Q1/Q3 cryo-assemblies contain two 4.2 m long magnets (MQXFA) fabricated and by AUP. They are tested vertically before use in a cry-assembly. In this paper we are going to present the main features of the MQXFA design, results of vertical tests, and main lessons learned. We will also discuss lessons learned for future use of Nb_3Sn magnets in HEP colliders.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Warm to cold correlations and other test results of the MQXFA Low-Beta Quadrupole magnets for the High-Luminosity Large Hadron Collider

The production of the MQXFA low-beta quadrupole magnets for the High Luminosity LHC (HL-LHC) is quite advanced with about 20 magnets cold tested in vertical cryostat. The MQXFA magnets are fabricated by the US HL-LHC Accelerator Upgrade Project (AUP) and are being used in the Q1 and Q3 Inner Triplet (IT) elements of the HL-LHC, whereas CERN is fabricating similar magnets for Q2a and Q2b IT elements. These large-aperture, high-gradient quadrupole magnets are first-of-the-kind accelerator magnets introducing Nb_3Sn conductor to High Energy Physics colliders. At this point of MQXFA production there is sufficient data to look at warm to cold correlations for the HL-LHC and for future use of Nb_3Sn magnets in particle accelerators. Examples of warm-cold correlations discussed in this paper are: field quality (including the use of magnetic shims for low-order harmonics correction), magnetic length, magnetic axis and magnetic field angle. A summary of main test data will also be presented and discussed.

Kurian, F. [Brookhaven]↗