Over the first five years of operation the PHENIX experiment at RHIC has collected a wealth of data for various systems and collision energies that is providing valuable information for the ...understanding of the suppression pattern observed in central Au+Au collisions at . An overview on transverse-momentum (pT) spectra of π0 and η in different collision energies and systems is presented.
Signal shapes in multiwire proportional chamber-based TPCs Windelband, J. Alme T. Alt H. Appelshäuser M. Arslandok R. Averbeck E. Bartsch P. Becht L. Bratrud P. Braun-Munzinger H. Buesching H. Caines P. Christiansen F. Costa U. Frankenfeld J. J. Gaardhøje C. Garabatos P. Glässel T. Gunji H. Hamagaki J. W. Harris E. Hellbär H. Helstrup M. Ivanov J. Jung M. Jung A. Junique A. Kalweit R. Keidel S. Kirsch M. Kleiner M. Kowalski M. Krüger C. Lippmann M. Mager S. Masciocchi A. Matyja D. Miśkowiec R. H. Munzer L. Musa B. S. Nielsen J. Otwinowski M. Pikna A. Rehman R. Renfordt D. Röhrich H. S. Scheid C. Schmidt H. R. Schmidt K. Schweda Y. Sekiguchi D. Silvermyr B. Sitar J. Stachel K. Ullaland R. Veenhof V. Vislavicius J. Wiechula B
arXiv.org,
12/2023
Paper, Journal Article
Open access
A large-volume Time Projection Chamber (TPC) is the main tracking and particle identification (PID) detector of the ALICE experiment at the CERN LHC. PID in the TPC is performed via specific ...energy-loss measurements (dE/dx), which are derived from the average pulse-height distribution of ionization generated by charged-particle tracks traversing the TPC volume. During Runs 1 and 2, until 2018, the gas amplification stage was based on multiwire proportional chambers (MWPC). Signals from the MWPC show characteristic long negative tails after an initial positive peak due to the long ion drift times in the MWPC amplification region. This so-called ion tail can lead to a significant amplitude loss in subsequently measured signals, especially in the high-multiplicity environment of high-energy Pb-Pb collisions, which results in a degradation of the dE/dx resolution. A detailed study of the signal shapes measured with the ALICE TPC with the Ne-CO2 (90-10) and Ar-CO2 (90-10) gas mixtures is presented, and the results are compared with three-dimensional Garfield simulations. The impact of the ion tail on the PID performance is studied employing the ALICE simulation framework and the feasibility of an offline correction procedure to account for the ion tail is demonstrated.
Transverse momentum (\(p_{\rm T}\)) spectra measured by the PHENIX experiment at RHIC in Au + Au, d + Au and pp collisions at \(\sqrt{s_{\mathrm{NN}}} = 200 \mathrm{GeV}\) and in Au + Au collisions ...at \(\sqrt{s_{\mathrm{NN}}} = 62.4 \mathrm{GeV}\) are presented. A suppression of the yield of high \(p_{\rm T}\) hadrons in central Au + Au collisions by a factor 4-5 at \(p_{{\text{T}}} > 5\) is found relative to the pp reference scaled by the nuclear overlap function \(\langle T_\mathrm{AB} \rangle\). In contrast, direct photons are not suppressed in central Au + Au collisions and no suppression of high \(p_{\rm T}\) particles can be seen in d + Au collisions. This leads to the conclusion that the dense medium formed in central Au + Au collisions is responsible for the suppression.
Event reconstruction in the PHENIX central arm spectrometers Mitchell, J.T; Akiba, Y; Aphecetche, L ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2002, Volume:
482, Issue:
1-2
Journal Article
Peer reviewed
Open access
The central arm spectrometers for the PHENIX experiment at the Relativistic Heavy Ion Collider have been designed for the optimization of particle identification in relativistic heavy ion collisions. ...The spectrometers present a challenging environment for event reconstruction due to a very high track multiplicity in a complicated, focusing, magnetic field. In order to meet this challenge, nine distinct detector types are integrated for charged particle tracking, momentum reconstruction, and particle identification. The techniques which have been developed for the task of event reconstruction are described.
Recent results of the WA98 experiment with p and Pb induced reactions at 158 AGeV are presented. The invariant yield of direct photons in central Pb+Pb collisions is shown as a function of transverse ...momentum. A significant direct photon signal is seen at pT > 1.5 GeV/c. The results constitute the first observation of direct photons in ultrarelativistic heavy-ion collisions. Azimuthal gamma-gamma correlations at high pT were studied in search for a signal of jet-like structures. A clear indication for back-to-back correlations can be seen in p+A with a strong dependence on the pT of the photons and the size of the system. In Pb+Pb, in plane elliptic flow has been observed. Results on tranverse mass spectra of neutral pions measured at central rapidity are presented for impact parameter selected Pb+Pb collisions. In going from peripheral to medium central collisions, there is a nuclear enhancement increasing with transverse mass similar to the Cronin effect, while for very central collisions this enhancement appears to be weaker than expected. (Author)
We'll measure the differences of the dual variables and the gain of the objective function when creating new problems, which each has one inequality more than the starting LP-instance. These ...differences of the dual variables are naturally connected to the branches. Then we'll choose those differences of dual variables, so that for all combinations of choices at the connected branches, all dual inequalities will hold for sure. By adding the gain of each chosen branching, we get a total gain, which gives a better limit of the original problem. By this technique it is also possible to create cuts.
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