Abstract
The ALICE experiment is dedicated to the study of the quark gluon plasma in heavy-ion collisions at the CERN LHC. The Muon Forward Tracker (MFT) is under consideration by the ALICE experiment to be part of its program of detector upgrades to be installed during the LHC Long Shutdown 2 (LS2) planned for 2018. Designed as a silicon pixel detector added in the Muon Spectrometer acceptance (â4.0 < η < â2.5) upstream of the hadron absorber, the MFT will allow a drastic improvement of the measurements that are presently done with the Muon Spectrometer and, in addition, will give access to new measurements that are not possible with the present Muon Spectrometer setup. Motivations and preliminary results are discussed here, concerning the measurement of prompt and displaced charmonia, open heavy flavors, and low mass dimuons in central PbâPb collisions at = 5.5 TeV.
Highlights
Lepton-pair measurements always played a key-role in high energy nuclear physics: leptons arrive to the detectors almost unaffected, being not sensible to the strong color field dominating inside the QCD matter, providing an ideal tool to probe the whole evolution of nuclear collisions
Starting from the nominal interaction point (IP) the Muon Arm is composed of the following elements: a hadron absorber allowing a reliable muon identification; a dipole magnet providing a field integral of 3 Tm; a set of five tracking stations, each one composed of two cathode pad chambers with a spacial resolution of about ⌠100 Όm in the bending direction; an iron wall, which absorbs the residual secondary hadrons emerging from the front absorber; the muon trigger system, consisting of 4 resistive plate chambers, with a time resolution of about 2 ns
The ALICE experiment has already an intense physics program based on muon measurements, developed along three main directions: study of quarkonia production [2, 3], of open heavy flavor production [4, 5], of low mass dimuons [6]
Summary
Lepton-pair measurements always played a key-role in high energy nuclear physics: leptons arrive to the detectors almost unaffected, being not sensible to the strong color field dominating inside the QCD matter, providing an ideal tool to probe the whole evolution of nuclear collisions. The degradation of the kinematics, imposed by the presence of the hadron absorber, plays a crucial role in determining the mass resolution for the resonances, especially at low masses. To overcome these limitations, and better exploit the unique kinematic range accessible by the ALICE Muon Arm at the LHC, the Muon Forward Tracker (MFT) was proposed in the context of the ALICE upgrade plans, to take place in the years 2017/2018 during the LHC Long Shutdown 2. Correct matching rates as large as 60 % and offset resolutions of â 100 ÎŒm are expected already for muons with pT â 1 GeV/c; for pT â 3 GeV/c, less than 10 % of the muons is found to be wrongly matched and the offset resolution stays below 70 ÎŒm
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