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Free, publicly-accessible full text available December 1, 2024
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Abstract The Large Hadron Collider (LHC) at CERN will undergo major upgrades to increase the instantaneous luminosity up to 5–7.5×10 34 cm -2 s -1 . This High Luminosity upgrade of the LHC (HL-LHC) will deliver a total of 3000–4000 fb -1 of proton-proton collisions at a center-of-mass energy of 13–14 TeV. To cope with these challenging environmental conditions, the strip tracker of the CMS experiment will be upgraded using modules with two closely-spaced silicon sensors to provide information to include tracking in the Level-1 trigger selection. This paper describes the performance, in a test beam experiment, of the first prototype module based on the final version of the CMS Binary Chip front-end ASIC before and after the module was irradiated with neutrons. Results demonstrate that the prototype module satisfies the requirements, providing efficient tracking information, after being irradiated with a total fluence comparable to the one expected through the lifetime of the experiment.more » « less
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Free, publicly-accessible full text available November 1, 2024
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Free, publicly-accessible full text available November 1, 2024
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Abstract A description is presented of the algorithms used to reconstruct energy deposited in the CMS hadron calorimeter during Run 2 (2015–2018) of the LHC. During Run 2, the characteristic bunch-crossing spacing for proton-proton collisions was 25 ns, which resulted in overlapping signals from adjacent crossings. The energy corresponding to a particular bunch crossing of interest is estimated using the known pulse shapes of energy depositions in the calorimeter, which are measured as functions of both energy and time. A variety of algorithms were developed to mitigate the effects of adjacent bunch crossings on local energy reconstruction in the hadron calorimeter in Run 2, and their performance is compared.
Free, publicly-accessible full text available November 1, 2024 -
Free, publicly-accessible full text available November 1, 2024
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Free, publicly-accessible full text available November 1, 2024
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Abstract The Pandora Software Development Kit and algorithm libraries provide pattern-recognition logic essential to the reconstruction of particle interactions in liquid argon time projection chamber detectors. Pandora is the primary event reconstruction software used at ProtoDUNE-SP, a prototype for the Deep Underground Neutrino Experiment far detector. ProtoDUNE-SP, located at CERN, is exposed to a charged-particle test beam. This paper gives an overview of the Pandora reconstruction algorithms and how they have been tailored for use at ProtoDUNE-SP. In complex events with numerous cosmic-ray and beam background particles, the simulated reconstruction and identification efficiency for triggered test-beam particles is above 80% for the majority of particle type and beam momentum combinations. Specifically, simulated 1 GeV/ c charged pions and protons are correctly reconstructed and identified with efficiencies of 86.1 $$\pm 0.6$$ ± 0.6 % and 84.1 $$\pm 0.6$$ ± 0.6 %, respectively. The efficiencies measured for test-beam data are shown to be within 5% of those predicted by the simulation.more » « lessFree, publicly-accessible full text available July 1, 2024
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Abstract A search for decays to invisible particles of Higgs bosons produced in association with a top-antitop quark pair or a vector boson, which both decay to a fully hadronic final state, has been performed using proton-proton collision data collected at
by the CMS experiment at the LHC, corresponding to an integrated luminosity of 138$${\sqrt{s}=13\,\text {Te}\hspace{-.08em}\text {V}}$$ . The 95% confidence level upper limit set on the branching fraction of the 125$$\,\text {fb}^{-1}$$ Higgs boson to invisible particles,$$\,\text {Ge}\hspace{-.08em}\text {V}$$ , is 0.54 (0.39 expected), assuming standard model production cross sections. The results of this analysis are combined with previous$${\mathcal {B}({\textrm{H}} \rightarrow \text {inv})}$$ searches carried out at$${\mathcal {B}({\textrm{H}} \rightarrow \text {inv})}$$ , 8, and 13$${\sqrt{s}=7}$$ in complementary production modes. The combined upper limit at 95% confidence level on$$\,\text {Te}\hspace{-.08em}\text {V}$$ is 0.15 (0.08 expected).$${\mathcal {B}({\textrm{H}} \rightarrow \text {inv})}$$ Free, publicly-accessible full text available October 1, 2024 -
Free, publicly-accessible full text available October 1, 2024