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20th LOMONOSOV CONFERENCE ON ELEMENTARY PARTICLE PHYSICS
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COLLIDER PHYSICS
The ATLAS Tile Calorimeter Performance and Its Upgrade towards the High-Luminosity LHC
Ammara Ahmad (on Behalf of the ATLAS Collaboration) E-mail: ammara.ahmad@cern.ch Institue de Fisica d'Altes Energies (IFAE); Universitat Autonoma de Barcelona, Spain
Received January 16, 2022
The Tile Calorimeter (TileCal) is a sampling hadronic calorimeter covering the central region of the ATLAS experiment. TileCal uses steel as absorber and plastic scintillators as active medium. The scintillators are readout by the wavelength shifting fibres coupled to the photomultiplier tubes (PMTs). The analogue signals from the PMTs are amplified, shaped, digitized by sampling the signal every 25 ns. Each stage of the signal production is monitored and calibrated to better than 1% using multistage calibration systems. The performance of the calorimeter has been measured and monitored using calibration data, cosmic ray muons and the large sample of proton-proton collisions acquired during LHC Run II. The High-Luminosity phase of LHC, delivering five times the LHC nominal instantaneous luminosity, is expected to begin in 2027. TileCal will require new electronics to meet the requirements of a 1 MHz trigger, higher ambient radiation, and to ensure better performance under high pileup conditions. Changes to the electronics will also contribute to the data integrity and reliability of the system. New electronics prototypes were tested in laboratories as well as in beam tests. Results of the calorimeter calibration and performance during LHC Run II are summarized, the main features and beam test results obtained with the new front-end electronics are also presented.
Keywords: collider physics, ATLAS, calorimeter calibration.
English version: Moscow University Physics Bulletin. 2022. 77, No. 2. Pp. 156-158.
Tests of the Standard Model by Means of Y(3S) Meson Decays
with the BABAR Detector
Hossain Ahmed1'2'", Nafisa Tasneem1, Michael Roney2 (on Behalf of the BABAR Collaboration) E-mail: "hahmed@stfx.ca
1 Department of Physics, St. Francis Xavier University 4130 University Avenue, Antigonish, NS, B2G1E1, Canada 2Department of Physics and Astronomy, University of Victoria 3800 Finnerty Road, Victoria, BC, V8P5C2, Canada Received January 19, 2022
The BABAR detector collected a sample of 122 million T(3S) mesons, corresponding to an integrated luminosity of 28fb-1, operating the PEP-II e+e- collider at a center-of-mass energy of about 10.355GeV. This sample is the largest ever collected at that energy and provides unique opportunities to test several aspects
of the Standard Model. We report on a precision measurement of the ratio = bf(t(3s)^+Ji-) • ^he
result is in agreement with the Standard Model prediction and its uncertainty is almost an order of magnitude smaller than the only previous measurement reported by the CLEO collaboration. We also present a search for the Lepton Flavour Violating decays T(3S) ^ , unobservable in the SM, but predicted to be enhanced in several new physics extensions.
Keywords: the standard model, BABAR detector, PEP-II, lepton universality, charged lepton flavour violation. English version: Moscow University Physics Bulletin. 2022. 77, No. 2. Pp. 159-162.
