Difference: FJPPLHadronPhysics (11 vs. 12)
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| > > | In heavy-ion collisions, hard-scattered partons are produced early in the collision, which makes them an ideal probe of the QGP and for studying energy loss within the medium. This parton energy loss will be reflected in the suppression of the measured heavy-ion jet spectrum relative to a pp reference, also known as jet quenching. Jet measurements performed so far have shown that the jet spectrum in heavy-ion collisions does deviate from what would be expected if the heavy-ion collision could be treated as a simple superposition of independent pp collisions. After having measured the magnitude of jet quenching for inclusive jet production in Pb–Pb collisions from 2015 data within the HAD_04 project, based on the large data samples collected in 2018, we aim at further unravelling jet-medium interactions and the properties of the hot dense medium in QCD, by putting special emphasis on angular correlations of jets with charged hadrons, studied in jet pT bins, pT bins of the associated hadrons, and as a function of collision centrality. With the restart of the LHC for Run 3, we are now actively exploring within the HAD_04 project new jet quenching observables (jet substructure and dijet measurements). The future of ALICE at the Run 4 horizon and beyond is also being prepared within the same project. A Forward Calorimeter (FoCal) is indeed proposed as an addition to the ALICE experiment, to be installed in the LHC Long Shutdown 3. Its main physics motivation is to provide unique constraints on the low-x gluonic structure of protons and nuclei via forward measurements of direct photons. The unique experimental challenge involved is to discriminate single photons from pairs of very close-by photons originating from pi0 decays. This will require an electromagnetic calorimeter with clean two-shower separation on the mm scale followed by a conventional hadronic calorimeter. The design choice for the electromagnetic part is that of a hybrid Si-W sampling calorimeter, using both Si-pad and Si-pixel sensors. Both are challenging technologies, where the Si-pixel based technology is key to the two-shower separation, and will have to go significantly beyond state of the art. An intensive R&D program for Si-pad-W based technologies is ongoing at different laboratories in Japan. More recently, French groups have joined the project to carry out, in collaboration with Japanese groups, an innovative R&D program to equip the electromagnetic part of FoCal with a readout electronic. The ALICE FoCal electromagnetic calorimeter silicon sensor pads will be read out by the 72-channel HGCROC front-end (FE) ASIC by the OMEGA group, which measures the charge and the time of arrival at 40MHz frequency. Digitized signals from several FE are routed to an FPGA-based back-end (BE) system in charge of a first online data reduction. Further data processing is handled in a continuous, triggerless mode by the Common Readout Unit (CRU) PCIe40 electronics designed for the LHCb experiment, connected to the BE system via optical fibers, before final transmission to the O2 computing farm for on-line event filtering, calibration, and reconstruction. Such triggerless, FPGA-based readout architecture represents the future of readout of experiments at facilities providing extremely high-interaction rates. | |||||||
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French members : R. Guernane, G. Conesa Balbastre, J. Faivre, C. Furget, J. Norman, Y. Schutz, I. Belikov, A. Maire, F. Rami, B. Hippolyte, C. Kuhn | ||||||||
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