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Student Sessions 2025
No full textHello all! My name is Julia, I am an engineering physics student from Canada. My project has been to construct a prototype of a Beam Intensity Monitor for the Beam Instrumentation group. In this talk, I will discuss the challenges and methods that go into the construction and installation of the prototype, as well as the vacuum capability and motorization that makes this prototype unique.
Well, actually… My additional goal with this talk is to encourage you to take a second look at detectors and instrumentation. Beyond just seeing diagrams, we will look at the “behind the scenes” of experiments, using the construction of my Beam Intensity Monitor as an example
Production of the ATLAS ITk Strip End-Cap global structures for the Phase-II LHC Upgrade.
No full textThe inner detector of the current ATLAS experiment has been designed to operate in the environment of the present Large Hadron Collider (LHC). During the ATLAS Phase-II Upgrade, particle densities and radiation levels will exceed present levels by an order of magnitude. The instantaneous luminosity is expected to result in up to 200 proton-proton interactions per bunch crossing, reaching levels never before achieved. For this upgrade, the ATLAS Inner Tracker (ITk) will replace the existing ATLAS Inner Detector. The ATLAS ITk detector comprises multiple layers: the innermost ones are silicon pixel sensors optimized for high granularity, while the outer layers consist of silicon strip sensors tailored for precise tracking. The central part of the strip detector (Barrel) is composed of rectangular ∼25 and ∼50 mm long strip sensors. The forward regions of the strip tracker (End- Caps) are divided into six wheels per side, each incorporating trapezoidal sensors with varying lengths and strip pitches. The production of the mechanical structures of the ITk Strip End-Cap (EC) takes place at Nikhef, in Amsterdam. This process, including the production of individual components, quality control, integration, and final structural checks, is extensive and challenging. The final product must meet stringent specifications and maintain its integrity during transportation to CERN, assembly and installation into the ATLAS experiment. The present paper details the production and assembly process of the ITk Strip EC global structures and discusses the most relevant quality control tests performe
Enabling impedance measurements of energised superconducting circuits through differential probing
No full textImpedance measurements are essential for validating theelectrical integrity of superconducting magnets. However,traditional measurements are conducted on de-energised circuits,restricting the ability to perform continuous validation. To enablemeasurements on energised systems, several challenges must beaddressed. Key of which, the presence of the power converter altersthe impedance of the system, and these effects need to be isolatedto enable accurate impedance measurements. Additionally, thestimulus signal used for measurement must be designed to preventdegradation of the operational performance of any peripheralequipment, such as the power converter. In this study, a methodutilising multiple voltage sources to inject differential stimuli isproposed, allowing the decoupling of impedances within the circuit'selements from the power converter. This approach enables themeasurement of each segment's isolated impedance. The method isdemonstrated on an energised superconducting quadrupole magnet andserves as a proof of principle. Further theoretical and practicalvalidation is required to assess its performance under realisticoperating conditions and its integration within a fullinstallation
New ATLAS results on H to boson-pair decays
No full textUnderstanding the properties of the Higgs boson remains central to testing the Standard Model and probing for new physics. This proceeding presents recent ATLAS results using proton–proton collision data using the full Run 2 and partial Run 3 datasets. Higgs boson production is studied in the H → W W → ℓνℓν final state using both on-shell and off-shell regimes. Off-shell production is probed via events with high dilepton mass and missing transverse energy. An observed (expected) upper limit of 13.1 (17.3) MeV is set on the Higgs boson total width by combining off-shell and on-shell measurements using the full Run 2 dataset. Additionally, inclusive and differential cross sections are measured in H → W W ∗ → ℓνℓν using the full Run 2 dataset and in H → ZZ∗ → 4ℓ with partial Run 3 data, and interpreted in the framework of the Standard Model Effective Field Theory, placing constraints on CP-even and CP-odd operators. These complementary approaches provide a coherent picture of Higgs interactions and offer avenues to search for physics beyond the Standard Model
Study of Higgs boson pair production in the final state with 308 fb of data collected at TeV and 13.6 TeV by the ATLAS experiment
No full textA search for Higgs boson pair production in the final state is performed. The proton-proton collision dataset corresponds to an integrated luminosity of 308 fb, consisting of two samples, 140 fb at a centre-of-mass energy of 13 TeV and 168 fb at 13.6 TeV, recorded between 2015 and 2024 by the ATLAS detector at the CERN Large Hadron Collider. In addition to a larger dataset, this analysis improves upon the previous search in the same final state through several methodological and technical developments. The Higgs boson pair production cross section divided by the Standard Model prediction is found to be ( expected), which translates into a 95% confidence-level upper limit of . At the same confidence level the Higgs self-coupling modifier is constrained to be in the range ( expected).A search for Higgs boson pair production in the final state is performed. The proton-proton collision dataset in this analysis corresponds to an integrated luminosity of 308 fb, consisting of two samples, 140 fb at a centre-of-mass energy of 13 TeV and 168 fb at 13.6 TeV, recorded between 2015 and 2024 by the ATLAS detector at the CERN Large Hadron Collider. In addition to a larger dataset, this analysis improves upon the previous search in the same final state through several methodological and technical developments. The Higgs boson pair production cross section divided by the Standard Model prediction is found to be ( expected), which translates into a 95% confidence-level upper limit of . At the same confidence level the Higgs self-coupling modifier is constrained to be in the range ( expected)
Search for the rare decay in proton-proton collisions at 13.6 TeV
No full textA search for the rare decay is reported using proton-proton collision events at 13.6 TeV collected by the CMS detector in 2022-2023, corresponding to an integrated luminosity of 64.5 fb. This is the first analysis to use a newly developed inclusive dimuon trigger, expanding the scope of the CMS flavor physics program. The search uses mesons obtained from decays. No significant excess is observed. A limit on the branching fraction of \mathcal{B}(\mathrm{D^0}\to\mu^{+}\mu^{-}) D0→μ+μ- is reported using proton-proton collision events at s=13.6 TeV collected by the CMS detector in 2022–2023, corresponding to an integrated luminosity of 64.5 fb-1. This is the first analysis to use a newly developed inclusive dimuon trigger, expanding the scope of the CMS flavor physics program. The search uses D0 mesons obtained from D*+→D0π+ decays. No significant excess is observed. A limit on the branching fraction of B(D0→μ+μ-)<2.4×10-9 at 95% confidence level is set. This is the most stringent upper limit set on any flavor changing neutral current decay in the charm sector.A search for the rare decay D^0μ^+μ^-\sqrt{s}-^{-1}^0^{*+}\to$ D$^0π^+$ decays. No significant excess is observed. A limit on the branching fraction of $\mathcal{B}$(D$^0\toμ^+μ^-\lt\times^{-9}$ at 95% confidence level is set. This is the most stringent upper limit set on any flavor changing neutral current decay in the charm sector