More Like this

1. Operation and performance of the ATLAS tile calorimeter in LHC Run 2

   https://doi.org/10.1140/epjc/s10052-024-13151-4  

   Aad, G; Abbott, B; Abdallah, J; Abeling, K; Abicht, N J; Abidi, S H; Aboulhorma, A; Abramowicz, H; Abreu, H; Abulaiti, Y; et al (December 2024, The European Physical Journal C)

   Abstract The ATLAS tile calorimeter (TileCal) is the hadronic sampling calorimeter covering the central region of the ATLAS detector at the Large Hadron Collider (LHC). This paper gives an overview of the calorimeter’s operation and performance during the years 2015–2018 (Run 2). In this period, ATLAS collected proton–proton collision data at a centre-of-mass energy of 13 TeV and the TileCal was 99.65% efficient for data-taking. The signal reconstruction, the calibration procedures, and the detector operational status are presented. The performance of two ATLAS trigger systems making use of TileCal information, the minimum-bias trigger scintillators and the tile muon trigger, is discussed. Studies of radiation effects allow the degradation of the output signals at the end of the LHC and HL-LHC operations to be estimated. Finally, the TileCal response to isolated muons, hadrons and jets from proton–proton collisions is presented. The energy and time calibration methods performed excellently, resulting in good stability and uniformity of the calorimeter response during Run 2. The setting of the energy scale was performed with an uncertainty of 2%. The results demonstrate that the performance is in accordance with specifications defined in the Technical Design Report. 

   more » « less
2. Distance-Weighted Graph Neural Networks on FPGAs for Real-Time Particle Reconstruction in High Energy Physics

   https://doi.org/10.3389/fdata.2020.598927  

   Iiyama, Yutaro; Cerminara, Gianluca; Gupta, Abhijay; Kieseler, Jan; Loncar, Vladimir; Pierini, Maurizio; Qasim, Shah Rukh; Rieger, Marcel; Summers, Sioni; Van Onsem, Gerrit; et al (January 2021, Frontiers in Big Data)

   null (Ed.)

   Graph neural networks have been shown to achieve excellent performance for several crucial tasks in particle physics, such as charged particle tracking, jet tagging, and clustering. An important domain for the application of these networks is the FGPA-based first layer of real-time data filtering at the CERN Large Hadron Collider, which has strict latency and resource constraints. We discuss how to design distance-weighted graph networks that can be executed with a latency of less than one μs on an FPGA. To do so, we consider a representative task associated to particle reconstruction and identification in a next-generation calorimeter operating at a particle collider. We use a graph network architecture developed for such purposes, and apply additional simplifications to match the computing constraints of Level-1 trigger systems, including weight quantization. Using the hls4ml library, we convert the compressed models into firmware to be implemented on an FPGA. Performance of the synthesized models is presented both in terms of inference accuracy and resource usage. 

   more » « less
3. Muon identification using multivariate techniques in the CMS experiment in proton-proton collisions at sqrt(s) = 13 TeV

   https://doi.org/10.1088/1748-0221/19/02/P02031  

   Hayrapetyan, A; Tumasyan, A; Adam, W; Andrejkovic, JW; Bergauer, T; Chatterjee, S; Damanakis, K; Dragicevic, M; Escalante_Del_Valle, A; Hussain, PS; et al (February 2024, Journal of Instrumentation)

   Abstract The identification of prompt and isolated muons, as well as muons from heavy-flavour hadron decays, is an important task. We developed two multivariate techniques to provide highly efficient identification for muons with transverse momentum greater than 10 GeV. One provides a continuous variable as an alternative to a cut-based identification selection and offers a better discrimination power against misidentified muons. The other one selects prompt and isolated muons by using isolation requirements to reduce the contamination from nonprompt muons arising in heavy-flavour hadron decays. Both algorithms are developed using 59.7 fb^-1of proton-proton collisions data at a centre-of-mass energy of √(s)=13 TeV collected in 2018 with the CMS experiment at the CERN LHC. 

   more » « less
4. The MUSE Beam Line Calorimeter

   https://doi.org/10.1051/epjconf/202532000031  

   Lin, Win (January 2025, EPJ Web of Conferences)

   Chujo, T; Ootani, W (Ed.)

   The MUon proton Scattering Experiment (MUSE) at the PiM1 beam line of the Paul Scherrer Institute is simultaneously measuring the elastic scattering of electrons and muons from a liquid hydrogen target to extract the charge radius of the proton with both positive and negative beam polarities. In addition to providing precise data for addressing the proton radius puzzle, comparing the four scattering cross sections directly tests lepton universality, radiative corrections, and two-photon exchange effects for electrons and muons. In order to study radiative correction and get more precise incident lepton energy at the scattering vertex for the cross section measurements, MUSE uses a lead-glass calorimeter located at the downstream end of the beam line. This proceeding discusses the specifications and calibration process of the calorimeter detector. Data are compared to simulation to demonstrate the performance of the detector. 

   more » « less
5. A search for heavy Higgs bosons decaying into vector bosons in same-sign two-lepton final states in pp collisions at $$ \sqrt{s} $$ = 13 TeV with the ATLAS detector

   https://doi.org/10.1007/JHEP07(2023)200  

   Aad, G.; Abbott, B.; Abbott, D. C.; Abeling, K.; Abidi, S. H.; Aboulhorma, A.; Abramowicz, H.; Abreu, H.; Abulaiti, Y.; Abusleme Hoffman, A. C.; et al (July 2023, Journal of High Energy Physics)

   A bstract A search for heavy Higgs bosons produced in association with a vector boson and decaying into a pair of vector bosons is performed in final states with two leptons (electrons or muons) of the same electric charge, missing transverse momentum and jets. A data sample of proton–proton collisions at a centre-of-mass energy of 13 TeV recorded with the ATLAS detector at the Large Hadron Collider between 2015 and 2018 is used. The data correspond to a total integrated luminosity of 139 fb − 1 . The observed data are in agreement with Standard Model background expectations. The results are interpreted using higher-dimensional operators in an effective field theory. Upper limits on the production cross-section are calculated at 95% confidence level as a function of the heavy Higgs boson’s mass and coupling strengths to vector bosons. Limits are set in the Higgs boson mass range from 300 to 1500 GeV, and depend on the assumed couplings. The highest excluded mass for a heavy Higgs boson with the coupling combinations explored is 900 GeV. Limits on coupling strengths are also provided. 

   more » « less