2,437 research outputs found
Aging and rate effects of the Multigap RPC studied at the Gamma Irradiation Facility at CERN
No full textThe selected device for the ALICE Time-of-Flight array is the Multigap Resistive Plate Chamber (MRPC). Previously we have tested this device at the Gamma Irradiation Facility (GIF) at CERN to evaluate the rate dependence; we have now performed additional tests using the final design of the MRPC and with a gas mixture free of hydrocarbons. We have measured the performance of the MRPC up to an equivalent flux of minimum ionizing muons of 2.5 kHz/cm2. We also present results from an aging test obtained by exposing two MRPC strips to the GIF source for a period of six months
Measurement of prompt D, D, D, and D production in pPb collisions at = 5.02 TeV
No full textThe measurement of the production of prompt D, D, D, and D mesons in pPb collisions at the centre-of-mass energy per nucleon pair of = 5.02 TeV, with an integrated luminosity of 292 ± 11b, are reported. Differential production cross sections are measured at mid-rapidity (0.96< < 0.04) as a function of transverse momentum () in the intervals 0 < < 36 GeV/for D, 1 < < 36 GeV/ for D and D, and 2 < < 24 GeV/ for D mesons. For each species, the nuclear modification factor R is calculated as a function of using a pp reference measured at the same collision energy. The results are compatible with unity in the whole range. The average of the non-strange D mesons R is compared with theoretical model predictions that include initial-state effects and parton transport model predictions. The dependence of the D, D, and D nuclear modification factors is also reported in the interval 1< < 36 GeV/ as a function of the collision centrality, and the central-to-peripheral ratios are computed from the D-meson yields in different centrality classes. The results are further compared with charged-particle measurements and a similar trend is observed in all the centrality classes. The ratios of the -differential cross sections of D, D, D, and D mesons are also reported. The D+s and D+ yields are compared as a function of the charged-particle multiplicity for several intervals. No modification in the relative abundances of the four species is observed with respect to proton-proton (pp) collisions within the statistical and systematic uncertainties.The measurement of the production of prompt D, D, D, and mesons in proton–lead (p–Pb) collisions at the centre-of-mass energy per nucleon pair of = 5.02 TeV, with an integrated luminosity of 292 ± 11 μb, are reported. Differential production cross sections are measured at mid-rapidity (−0.96 < y< 0.04) as a function of transverse momentum (p) in the intervals 0 < p< 36 GeV/c for D, 1 < p< 36 GeV/c for D and D, and 2 < p< 24 GeV/c for D mesons. For each species, the nuclear modification factor R is calculated as a function of p using a proton-proton (pp) ref- erence measured at the same collision energy. The results are compatible with unity in the whole p range. The average of the non-strange D mesons R is compared with theoretical model predictions that include initial-state effects and parton transport model predictions. The p dependence of the D, D, and D nuclear modification factors is also reported in the interval 1 < p< 36 GeV/c as a function of the collision centrality, and the central-to-peripheral ratios are computed from the D-meson yields measured in different centrality classes. The results are further compared with charged-particle measurements and a similar trend is observed in all the centrality classes. The ratios of the p-differential cross sections of D, D, D, and mesons are also reported. The and D yields are compared as a function of the charged-particle multiplicity for several p intervals. No modification in the relative abundances of the four species is observed with respect to pp collisions within the statistical and systematic uncertainties.The measurement of the production of prompt D, D, D, and D mesons in protonlead (pPb) collisions at the centre-of-mass energy per nucleon pair of = 5.02 TeV, with an integrated luminosity of b, are reported. Differential production cross sections are measured at mid-rapidity () as a function of transverse momentum () in the intervals GeV/ for D, GeV/ for D and D, and GeV/ for D mesons. For each species, the nuclear modification factor is calculated as a function of using a proton-proton (pp) reference measured at the same collision energy. The results are compatible with unity in the whole range. The average of the non-strange D mesons is compared with theoretical model predictions that include initial-state effects and parton transport model predictions. The dependence of the D, D, and D nuclear modification factors is also reported in the interval GeV/ as a function of the collision centrality, and the central-to-peripheral ratios are computed from the D-meson yields measured in different centrality classes. The results are further compared with charged-particle measurements and a similar trend is observed in all the centrality classes. The ratios of the -differential cross sections of D, D, D, and D mesons are also reported. The D and D yields are compared as a function of the charged-particle multiplicity for several intervals. No modification in the relative abundances of the four species is observed with respect to pp collisions within the statistical and systematic uncertainties
ALICE Time Of Flight Detector
No full textCharged particles in the intermediate momentum range are identified in ALICE by the Time Of Flight (TOF) detector. The time measurement with the TOF, in conjunction with the momentum and track length measured by the tracking detector, is used to calculate the particle mass
Measurement of D-0, D+, D+* and D-s(+) production in pp collisions at root s=5.02 TeV with ALICE
No full textThe measurements of the production of prompt D0 , D+ , D∗+ , and D+s mesons in proton–proton (pp) col- lisions at √s = 5.02 TeV with the ALICE detector at the Large Hadron Collider (LHC) are reported. D mesons were reconstructed at mid-rapidity (|y| < 0.5) via their hadronic decay channels D0 → K−π+, D+ → K−π+π+, D∗+ → D0π+ → K−π+π+, D+s → φπ+ → K+K−π+, and their charge conjugates. The production cross sections were measured in the transverse momentum interval 0 < pT < 36GeV/cforD0,1 < pT < 36GeV/cforD+ and D∗+, and in 2 < pT < 24 GeV/c for D+s mesons. Thanks to the higher integrated luminosity, an analysis in finer pT bins with respect to the previous measurements at √s = 7 TeV was performed, allowing for a more detailed description of the cross-section pT shape. The measured pT- differential production cross sections are compared to the results at √s = 7 TeV and to four different perturbative QCD calculations. Its rapidity dependence is also tested combin- ing the ALICE and LHCb measurements in pp collisions at √s = 5.02 TeV. This measurement will allow for a more accurate determination of the nuclear modification factor in p–Pb and Pb–Pb collisions performed at the same nucleon– nucleon centre-of-mass energy
The multigap resistive plate chamber as a time-of-flight detector
No full textThe goal of this R&D has been to reach the time resolution needed for time-of-flight detectors using the Multigap Resistive Plate Chamber (MRPC). We present here a MRPC with a time resolution of 70 ps. This prototype has been studied within the R&D program for the very large area TOF array of the ALICE experiment at the CERN LHC. (5 refs)
Experimental study of the time resolution of SiPM coupled to scintillator
No full textVarious experiments are searching for detectors that can cover large areas (as in the present LHC experiments) with excellent timing performances and insensitivity to magnetic field. A detector based on scintillators coupled to SiPM can fulfil these requirements. SiPMs are indeed replacing the standard PhotoMultiplier technology thanks to the many advantages, with the corresponding possibility to achieve also higher segmentations in calorimetry or other applications. Also in view of future colliders experiments like HL-LHC or FCC or medical applications like TOF-PET, an important R&D on timing performances of SiPMs-scintillator detectors has begun, with the goal of including them in the list of possible 4-D tracking-timing devices. An R&D on SiPM coupled to scintillator time resolution has been performed in a cosmic ray setup. Different kind of SiPMs, geometries of SiPMs coupled to the scintillator and different size of scintillator have been also studied. A time resolution of ∼69 ps, comprehensive of the full electronic chain, from the front-end to the readout electronics, has been achieved with SiPMs coupled to a 2x2x3 cm3 plastic scintillator
Measurement of D-0, D+, D*+ and D-s(+) production in Pb-Pb collisions at root s(NN)=5:02 TeV
No full textWe report measurements of the production of prompt D0, D+, D*+ and Ds + mesons in Pb–Pb collisions at the centre-of-mass energy per nucleon-nucleon pair sNN=5.02 TeV, in the centrality classes 0–10%, 30–50% and 60–80%. The D-meson production yields are measured at mid-rapidity (|y| 8 GeV/c, while it is larger at lower pT. The nuclear modification factors for strange and non-strange D mesons are also compared to theoretical models with different implementations of in-medium energy loss
Measurement of prompt D0, D+, D*+, and DS+ production in p–Pb collisions at √sNN = 5.02 TeV
No full textThe measurement of the production of prompt D0, D+, D∗+, and D+s mesons in proton–lead (p–Pb) collisions at the centre-of-mass energy per nucleon pair of √sNN = 5.02 TeV, with an integrated luminosity of 292 ± 11 μb−1, are reported. Differential pro- duction cross sections are measured at mid-rapidity (−0.96 < ycms < 0.04) as a function of transverse momentum (pT) in the intervals 0 < pT < 36 GeV/c for D0, 1 < pT < 36 GeV/c for D+ and D∗+, and 2 < pT < 24GeV/c for D+s mesons. For each species, the nuclear modification factor RpPb is calculated as a function of pT using a proton-proton (pp) ref- erence measured at the same collision energy. The results are compatible with unity in the whole pT range. The average of the non-strange D mesons RpPb is compared with theoretical model predictions that include initial-state effects and parton transport model predictions. The pT dependence of the D0, D+, and D∗+ nuclear modification factors is also reported in the interval 1 < pT < 36 GeV/c as a function of the collision centrality, and the central-to-peripheral ratios are computed from the D-meson yields measured in different centrality classes. The results are further compared with charged-particle measurements and a similar trend is observed in all the centrality classes. The ratios of the pT-differential cross sections of D0, D+, D∗+, and D+s mesons are also reported. The D+s and D+ yields are compared as a function of the charged-particle multiplicity for several pT intervals. No modification in the relative abundances of the four species is observed with respect to pp collisions within the statistical and systematic uncertainties
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