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Silicon drift chamber studies for possible use at RHIC. Final report, March 1, 1989--April 30, 1993
No full textThis is the final report for the DOE project ``Silicon Drift-Chamber studies for Possible use at RHIC`` carried out at the University of Pittsburgh by T. J. Humanic. This study was carried out during the period March 1989--April 1993 under DOE Grant No. DE-FG02-89ER40503. The termination of this grant was caused by the movement of the principal investigator from the University of Pittsburgh to Ohio State University, where this work is continuing under a different grant. During this period we investigated various aspects of silicon drift chambers including two-track resolution, effects of external magnetic fields and different detector designs
Probe station for testing of ALICE silicon drift detectors
No full textLarge area, 7.25 cm multiplied by 8.76 cm silicon drift detectors have been developed and are in production for the ALICE experiment at LHC. An active area of the detector of more than 50 cm**2 imposes high demands on the quality of processing and raw material. Automated testing procedures have been developed to test detectors before mounting them on the ladders. Probe stations for ALICE SDD testing were designed and built at INFN, Trieste and Ohio State University (OSU). Testing procedures, detector selection criteria and some details of the OSU probe station design are discussed
First measurement of the vertical bar t vertical bar-dependence of coherent J/psi photonuclear production
No full textThe first measurement of the cross section for coherent J/Psi photoproduction as a function of vertical bar t vertical bar, the square of the momentum transferred between the incoming and outgoing target nucleus, is presented. The data were measured with the ALICE detector in ultra-peripheral Pb-Pbcollisions at a centre-of-mass energy per nucleon pair root s(NN) = 5.02 TeV with the J/Psi produced in the central rapidity region vertical bar y vertical bar < 0.8, which corresponds to the small Bjorken-xrange (0.3 - 1.4) x 10(-3). The measured vertical bar t vertical bar-dependence is not described by computations based only on the Pb nuclear form factor, while the photonuclear cross section is better reproduced by models including shadowing according to the leading-twist approximation, or gluon-saturation effects from the impact-parameter dependent Balitsky-Kovchegov equation. These new results are therefore a valid tool to constrain the relevant model parameters and to investigate the transverse gluonic structure at very low Bjorken- x. (C) 2021 The Author(s). Published by Elsevier B.V
First Measurement of the |t| Dependence of Incoherent J/ψ Photonuclear Production
No full textThe first measurement of the cross section for incoherent photonuclear production of J/ψ vector mesons as a function of the Mandelstam |t| variable is presented. The measurement was carried out with the ALICE detector at midrapidity, |y|<0.8, using ultraperipheral collisions of Pb nuclei at a center-of-mass energy per nucleon pair of √sNN=5.02 TeV. This rapidity interval corresponds to a Bjorken-x range (0.3–1.4)×10−3. Cross sections are given in five |t| intervals in the range 0.04<|t|<1 GeV2 and compared to the predictions by different models. Models that ignore quantum fluctuations of the gluon density in the colliding hadron predict a |t| dependence of the cross section much steeper than in data. The inclusion of such fluctuations in the same models provides a better description of the data
Mini black holes at the LHC : discovery through di-jet suppression, mono-jet emission and a supersonic boom in the quark-gluon plasma in ALICE, ATLAS and CMS
No full textWe examine experimental signatures of TeV-mass black hole formation in heavy ion collisions at the LHC. We find that the black hole production results in a complete disappearance of all very high p_T (> 500 GeV) back-to-back correlated di-jets of total mass M > M_f ~ 1 TeV. We show that the subsequent Hawking-decay produces multiple hard mono-jets and discuss their detection. We study the possibility of cold black hole remnant (BHR) formation of mass ~ M_f and the experimental distinguishability of scenarios with BHRs and those with complete black hole decay. Finally we point out that a Heckler-Kapusta-Hawking plasma may form from the emitted mono-jets. In this context we present new simulation data of Mach shocks and of the evolution of initial conditions until the freeze-out
J/ψ production at midrapidity in p-Pb collisions at √sNN = 8.16 TeV
No full textThe production of inclusive, prompt and non-prompt J/ψ was studied for the first time at midrapidity (−1.37 2 GeV/c. The study of the J/ψ mesons in the dielectron channel used for the first time in ALICE online single-electron triggers from the Transition Radiation Detector, providing a data sample corresponding to an integrated luminosity of 689 ± 13 μb −1. The proton-proton reference cross section for inclusive J/ψ was obtained based on interpolations of measured data at different centre-of-mass energies and a universal function describing the p T-differential J/ψ production cross sections. The p T-differential nuclear modification factors R pPb of inclusive, prompt, and non-prompt J/ψ are consistent with unity and described by theoretical models implementing only nuclear shadowing. [Figure not available: see fulltext.
First Measurement of the |t | Dependence of Incoherent J/ψ Photonuclear Production
No full textThe first measurement of the cross section for incoherent photonuclear production of J/ψ vector mesons as a function of the Mandelstam |t| variable is presented. The measurement was carried out with the ALICE detector at midrapidity, |y|<0.8, using ultraperipheral collisions of Pb nuclei at a center-of-mass energy per nucleon pair of sNN=5.02 TeV. This rapidity interval corresponds to a Bjorken-x range (0.3-1.4)×10-3. Cross sections are given in five |t| intervals in the range 0.04<|t|<1 GeV2 and compared to the predictions by different models. Models that ignore quantum fluctuations of the gluon density in the colliding hadron predict a |t| dependence of the cross section much steeper than in data. The inclusion of such fluctuations in the same models provides a better description of the data
Double particle resolution measured in a silicon drift chamber
No full textThe two-hit resolution of a silicon drift chamber is measured using a pulsed Nd: YAG laser and a time digitizer readout. The data is analyzed by forming the covariance matrix in time samples, and transforming to a matrix in amplitude and time variation of each of the two hits. The resolution on the two-hit separation is found to be better than 25 μm with a drift field of 530 V/cm and a separation of more than 500 μm, with the resolution increasing to 50 μm as the separation nears 500 μ. Results are also presented for multiply ionizing tracks, showing a great improvement over single minimum ionizin
First measurement of the vertical bar t vertical bar-dependence of coherent J/psi photonuclear production
No full textThe first measurement of the cross section for coherent J/ψ photoproduction as a function of |t|, the square of the momentum transferred between the incoming and outgoing target nucleus, is presented. The data were measured with the ALICE detector in ultra-peripheral Pb–Pb collisions at a centre-of-mass energy per nucleon pair sNN=5.02TeV with the J/ψ produced in the central rapidity region |y|<0.8, which corresponds to the small Bjorken-x range (0.3−1.4)×10−3. The measured |t|-dependence is not described by computations based only on the Pb nuclear form factor, while the photonuclear cross section is better reproduced by models including shadowing according to the leading-twist approximation, or gluon-saturation effects from the impact-parameter dependent Balitsky–Kovchegov equation. These new results are therefore a valid tool to constrain the relevant model parameters and to investigate the transverse gluonic structure at very low Bjorken-x
Rapidity and transverse-momentum dependence of the inclusive J/ψ nuclear modification factor in p-Pb collisions at = 5.02 TeV
No full textWe have studied the transverse-momentum (p(T)) dependence of the inclusive J/psi production in p-Pb collisions at root s(NN) = 5.02 TeV, in three center-of-mass rapidity (y(cms)) regions, down to zero p(T). Results in the forward and backward rapidity ranges (2.03 < y(cms) < 3.53 and -4.46 < y(cms) < -2.96) are obtained by studying the J/psi decay to mu(+)mu(-), while the mid-rapidity region (-1.37 < y(cms) < 0.43) is investigated by measuring the e(+)e(-) decay channel. The p(T) dependence of the J/psi production cross section and nuclear modification factor are presented for each of the rapidity intervals, as well as the J/psi mean p(T) values. Forward and mid-rapidity results show a suppression of the J/psi yield, with respect to pp collisions, which decreases with increasing p(T). At backward rapidity no significant J/psi suppression is observed. Theoretical models including a combination of cold nuclear matter effects such as shadowing and partonic energy loss, are in fair agreement with the data, except at forward rapidity and low transverse momentum. The implications of the p-Pb results for the evaluation of cold nuclear matter effects on J/psi production in Pb-Pb collisions are also discussed
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