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Adam, W.

Publications and source records attributed to Adam, W..

At least 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Study of Jet Quenching with Z + jet Correlations in Pb-Pb and p p Collisions at s N N = 5.02 TeV

The production of jets in association with Z bosons, reconstructed via the μ + μ – and e + e – decay channels, is studied in p p and, for the first time, in Pb-Pb collisions. Both data samples were collected by the CMS experiment at the LHC, at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The Pb-Pb collisions were analyzed in the 0%–30% centrality range. The back-to-back azimuthal alignment was studied in both p p and Pb-Pb collisions for Z bosons with transverse momentum p T Z > 60 GeV / c and a recoiling jet with p T jet > 30 GeV / c . The p T imbalance x j Z = p T jet / p T Z , as well as the average number of jet partners per Z , R j Z , was studied in intervals of p T Z . The R j Z is found to be smaller in Pb-Pb than in p p collisions, which suggests that in Pb-Pb collisions a larger fraction of partons associated with the Z bosons fall below the 30 GeV / c p T jet threshold because they lose energy.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Characterisation of irradiated thin silicon sensors for the CMS phase II pixel upgrade

The high luminosity upgrade of the Large Hadron Collider, foreseen for 2026, necessitates the replacement of the CMS experiment’s silicon tracker. The innermost layer of the new pixel detector will be exposed to severe radiation, corresponding to a 1 MeV neutron equivalent fluence of up to $\Phi _{eq} = 2 \times 10^{16}$ cm$^{-2}$ , and an ionising dose of ${\approx } 5$ MGy after an integrated luminosity of 3000 fb$^{-1}$ . Thin, planar silicon sensors are good candidates for this application, since the degradation of the signal produced by traversing particles is less severe than for thicker devices. In this paper, the results obtained from the characterisation of 100 and 200 $\upmu $ m thick p-bulk pad diodes and strip sensors irradiated up to fluences of $\Phi _{eq} = 1.3 \times 10^{16}$ cm$^{-2}$ are shown.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2017

P-Type Silicon Strip Sensors for the new CMS Tracker at HL-LHC

The upgrade of the LHC to the High-Luminosity LHC (HL-LHC) is expected to increase the LHC design luminosity by an order of magnitude. This will require silicon tracking detectors with a significantly higher radiation hardness. The CMS Tracker Collaboration has conducted an irradiation and measurement campaign to identify suitable silicon sensor materials and strip designs for the future outer tracker at the CMS experiment. Based on these results, the collaboration has chosen to use n-in-p type silicon sensors and focus further investigations on the optimization of that sensor type. This paper describes the main measurement results and conclusions that motivated this decision.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2017

Measurements of the charm jet cross section and nuclear modification factor in pPb collisions at s NN = 5.02 TeV

The CMS Collaboration presents the first measurement of the differential cross section of jets from charm quarks produced in proton-lead (pPb) collisions at a nucleon-nucleon center-of-mass energy of $\sqrt{s{NN}}$ = 5.02 TeV, as well as results from charm quark jets in proton-proton (pp) collisions at $\sqrt{s}$= 2.76 and 5.02 TeV. By comparing the yields of the pPb and pp collision systems at the same energy, a nuclear modification factor for charm jets in pPb collisions at $\sqrt{s{NN}}$ = 5.02 TeV of $R_{pA}$ = 0.92 +/- 0.07 (stat) +/- 0.11 (syst) is obtained. This is consistent with an absence of final-state energy loss for charm quarks in pPb collisions. In addition, the fraction of jets coming from charm quarks is found to be consistent with that predicted by PYTHIA 6 for pp collisions at $\sqrt{s}$= 2.76 and 5.02 TeV, and is independent of the jet transverse momentum from 55 to 400 GeV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗