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Awes, Terry C

Publications and source records attributed to Awes, Terry C.

At least 55 records · Page 3
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DOE OSTI2012

Measurement of Charm Production at Central Rapidity in Proton-Proton Collisions at s = 7 TeV

The p{sub t}-differential inclusive production cross sections of the prompt charmed mesons D{sup 0}, D{sup +}, and D{sup {sm_bullet}+} in the rapidity range |y| < 0.5 were measured in proton-proton collisions at {radical}s = 7 TeV at the LHC using the ALICE detector. Reconstructing the decays D{sup 0} {yields} K{sup -}{pi}{sup +}, D{sup +} {yields} K{sup -}{pi}{sup +}{pi}{sup +}, D{sup {sm_bullet}+} {yields} D{sup 0}{pi}{sup +}, and their charge conjugates, about 8,400 D{sup 0}, 2,900 D{sup +}, and 2,600 D{sup {sm_bullet}+} mesons with 1 < p{sub t} < 24 GeV/c were counted, after selection cuts, in a data sample of 3.14 x 10{sup 8} events collected with a minimum-bias trigger (integrated luminosity L{sub int} = 5 nb{sup -1}). The results are described within uncertainties by predictions based on perturbative QCD.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2012

Measurement of Event Background Fluctuations for Charged Particle Jet Reconstruction in Pb-Pb Collisions at s_NN = 2.76 TeV

The effect of event background fluctuations on charged particle jet reconstruction in Pb-Pb collisions at {radical}s{sub NN} = 2.76 TeV has been measured with the ALICE experiment. The main sources of non-statistical fluctuations are characterized based purely on experimental data with an unbiased method, as well as by using single high pt particles and simulated jets embedded into real Pb-Pb events and reconstructed with the anti-kt jet finder. The influence of a low transverse momentum cut-off on particles used in the jet reconstruction is quantified by varying the minimum track pt between 0.15 GeV/c and 2 GeV/c. For embedded jets reconstructed from charged particles with p{sub t} > 0.15 GeV/c, the uncertainty in the reconstructed jet transverse momentum due to the heavy-ion background is measured to be 11.3 GeV/c (standard deviation) for the 10% most central Pb-Pb collisions, slightly larger than the value of 11.0 GeV/c measured using the unbiased method. For a higher particle transverse momentum threshold of 2 GeV/c, which will generate a stronger bias towards hard fragmentation in the jet finding process, the standard deviation of the fluctuations in the reconstructed jet transverse momentum is reduced to 4.8-5.0 GeV/c for the 10% most central events. A non-Gaussian tail of the momentum uncertainty is observed and its impact on the reconstructed jet spectrum is evaluated for varying particle momentum thresholds, by folding the measured fluctuations with steeply falling spectra.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Characterization of a New Charge Sensitive Preamplifier (CSP) for the Electromagnetic Calorimeters of the ALICE Experiment

The ALICE calorimeters PHOS and EMCal (including its extension DCal) are based on Avalanche Photo-Diode (APD) photosensors with Charge Sensitive Preamplifiers (CSPs) for readout of the scintillating elements. A new CSP has been developed on the basis of the design of the PHOS CSP, but modified to meet the requirements of the EMCal and DCal. Modifications were made specifically for a different APD choice with different characteristics, and also with the goals of less noise, faster rise time, and reduced cost. This paper presents a detailed description of the new CSP features and the test results.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2012

L0 Trigger for the EMCal Detector of the ALICE Experiment

The ALICE experiment at the CERN Large Hadron Collider (LHC) accelerator was designed to study ultra-relativistic heavy-ion collisions. The ALICE Electromagnetic Calorimeter (EMCal) was built to provide measurement of photons, electrons, and jets, and trigger selection of hard-QCD events containing them. The EMCal single-shower L0 trigger, which triggers on large energy deposit within a 4 x 4 tower sliding window, became operational in 2010. The implementation of the real-time FPGA based algorithm optimized to provide a fast L0 decision is presented.

43 PARTICLE ACCELERATORS↗
DOE OSTI2012

Harmonic decomposition of two particle angular correlations in Pb Pb collisions at s_NN = 2.76 TeV

Angular correlations between unidentified charged trigger (t) and associated (a) particles are measured by the ALICE experiment in Pb-Pb collisions at {radical}s{sub NN} = 2.76 TeV for transverse momenta 0.25 < p{sub T}{sup t,a} < 15 GeV/c, where p{sub T}{sup t} > p{sub T}{sup a}. The shapes of the pair correlation distributions are studied in a variety of collision centrality classes between 0 and 50% of the total hadronic cross section for particles in the pseudorapidity interval |{eta}| < 1.0. Distributions in relative azimuth {Delta}{phi}{triple_bond}{phi}t-{phi}a are analyzed for |{Delta}{eta}|{triple_bond}|{eta}t-{eta}a| > 0.8, and are referred to as 'long-range correlations'. Fourier components Vn{Delta} {triple_bond} <cos(n{Delta}{phi})> are extracted from the long-range azimuthal correlation functions. If particle pairs are correlated to one another through their individual correlation to a common symmetry plane, then the pair anisotropy V{sub n{Delta}}(p{sub T}{sup t},p{sub T}{sup a}) is fully described in terms of single-particle anisotropies vn(pT) as V{sub n{Delta}}(p{sub T}{sup t},p{sub T}{sup a}) = v{sub n}(p{sub T}{sup t})v{sub n}(p{sub T}{sup a}). This expectation is tested for 1 {le} n {le} 5 by applying a global fit of all V{sub n{Delta}}(p{sub T}{sup t},p{sub T}{sup a}) to obtain the best values vn{l_brace}GF{r_brace}(p{sub T}). It is found that for 2 {le} n {le} 5, the fit agrees well with data up to p{sub T}{sup a} {approx} 3-4 GeV/c, with a trend of increasing deviation as p{sub T}{sup t} and p{sub T}{sup a} are increased or as collisions become more peripheral. This suggests that no pair correlation harmonic can be described over the full 0.25 < pT < 15 GeV/c range using a single vn(pT) curve; such a description is however approximately possible for 2 {le} n {le} 5 when p{sub T}{sup a} < 4 GeV/c. For the n = 1 harmonic, however, a single v{sub 1}(pT) curve is not obtained even within the reduced range p{sub T}{sup a} < 4 GeV/c.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2012

Heavy Flavour Decay Muon Production at Forward Rapidity in Proton Proton Collisions at s = 7 TeV

The production of muons from heavy flavor decays is measured at forward rapidity in proton-proton collisions at {radical}s = 7 TeV collected with the ALICE experiment at the LHC. The analysis is carried out on a data sample corresponding to an integrated luminosity L{sub int} = 16.5 nb{sup -1}. The transverse momentum and rapidity differential production cross sections of muons from heavy flavour decays are measured in the rapidity range 2.5 < y < 4, over the transverse momentum range 2 < p{sub t} < 12 GeV/c. The results are compared to predictions based on perturbative QCD calculations.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2012

Light Vector Mesons in pp Collisions at s = 7 TeV

The ALICE experiment has measured low-mass dimuon production in pp collisions at {radical}s = 7 TeV in the dimuon rapidity region 2.5 < y < 4. The observed dimuon mass spectrum is described as a superposition of resonance decays ({eta},{rho},{omega},{eta}{prime},{phi}) into muons and semi-leptonic decays of charmed mesons. The measured production cross sections for {omega}and {phi} are {sigma}{sub {omega}}(1 < p{sub t} < 5 GeV/c, 2.5 < y < 4) = 5.28 {+-} 0.54(stat) {+-} 0.49(syst) mb and {sigma}{sub {phi}}(1 < p{sub t} < 5 GeV/c, 2.5 < y < 4) = 0.940 {+-} 0.084(stat) {+-} 0.076(syst) mb. The differential cross sections d{sup 2}{sigma}/dy dp{sub t} are extracted as a function of p{sub t} for {omega} and {phi}. The ratio between the {rho} and {omega} cross section is obtained. Results for the {phi} are compared with other measurements at the same energy and with predictions by models.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗