371 research outputs found
Direct Photons at the PHENIX Experiment: From Large to Small Systems
No full textDirect photons are a unique probe to study the properties of the medium created in heavy ion collisions. Low transverse momentum ( p T ) direct photons are of special interest since thermal photons are supposed to be dominant, while at high p T direct photons come from initial hard scattering (pQCD). PHENIX has observed a large excess of direct photon yield as well as large azimuthal anisotropy at low p T in Au+Au collisions at the c.m.s energy per nucleon pair s N N = 200 GeV. The mechanism to produce a large direct photon yield with a large elliptic anisotropy ( v 2 ) is not well understood yet. PHENIX has made systematic measurements of direct photons with different collision energies and system configurations. It has been found that direct photon yield d N γ / d η is proportional to charge particle multiplicity ( d N c h / d η ) 1 . 25 . This behavior holds for beam energies measured both at RHIC and at the LHC in large systems. This scaling suggests that there is a transition from p+p to A+A system which could be understood with the analysis of smaller systems like p+Au and d+Au
Popol Vuh: uma leitura cênica
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão, Programa de Pós-Graduação em Literatura, Florianópolis, 2012A presente pesquisa apresenta o relato de um processo criativo que possibilitou a adaptação do poema Popol Vuh. Essa cosmogonia ameríndia foi escrita na língua maia, no século XVI, na Guatemala. O relato mediado por ideias e pensamentos de estudiosos busca uma aproximação do leitor com esse processo criativo que resultou em uma encenação compartilhada com o público, em 2009. A encenação Ato Performático: Popol Vuh estruturou-se em acontecimentos cênicos inspirados nos eventos e personagens presentes no contexto literário do poema, e remetem as quatro criações que relatam a criação do homem americano, feito da pasta do milho. Para uma interação do leitor com esse processo criativo, a tese apresenta-se em dois capítulos: o primeiro, com imagens fotografadas, evidencia os elementos compartilhados pelo grupo de pesquisa, ao longo do processo de investigação, que contribuíram para a adaptação do poema. O segundo, sob o ponto de vista da encenadora pesquisadora e mediado por recortes teóricos, descreve o percurso trilhado pelo grupo no processo de apropriação e transposição dos elementos presentes e inspirados nessa cosmogonia para a composição e produção da encenação. Essa pesquisa transitou da investigação do universo literário do poema Popol Vuh para as práticas do fazer teatral e se realizou de forma interdisciplinar, em que iniciantes no teatro trocaram com profissionais da área artística.Abstract : This research presents the report of a creative process that led to the adaptation of the poem Popol Vuh. This Native American cosmogony was written in the Mayan language in the sixteenth century, in Guatemala. Mediated by ideas and thoughts of scholars, the report seeks to bring the reader to the creative process which finally resulted in a scenario shared with the public in 2009. The staging Performative Act: Popol Vuh was structured around scenic acts inspired by events and characters presented in the poem literary background, and refer to the four creations that report the creation of the American man, who's being made of corn paste. For an interaction of the reader with this creative process, the thesis is presented in two chapters: the first chapter, with photographed images, shows the elements shared by the research group, throughout the research process, which contributed to the adaptation of the poem. The second chapter describes, mediated by theoretic accounts and from the point of view of the stage director and researcher, the procedures taken by the group for the composition and production of the staging as the group looked for appropriation and implementation of the elements showed in and inspired by that cosmogony. The work moved from the research of the literary universe of the Popol Vuh poem to the practices of theater making, being held in an interdisciplinary approach where beginners actors exchanged with professionals ones
Detection of atmospheric muons using ALICE detectors
No full textA large number of atmospheric muon events were recorded during 2009 for the calibration, alignment and commissioning of most of the ALICE (A Large Ion Collider Experiment at the CERN LHC) detectors. Specific triggers, not used during the LHC colli sions, were implemented to take these data. Some triggers select atmospheric muons, with zenith angle between 0^o and 60^o, crossing the central barrel of ALICE and reconstructed with the TPC (Time Projection Chamber). The muon multiplicity of the event, and for each muon the momentum, the sign, the direction and the spatial coordinates are measured. We present a first analysis of these events with correlations between some observables. Another trigger selects horizontal muons with zenith angle between 65 ^o and 85^o. These muons are detected and reconstructed with the Forward Muon Spectrometer. The angular distribution and some characteristics of these rare events are discussed
Transverse single spin asymmetries of forward neutrons in p+p , p+Al , and p+Au collisions at \sqrt{s_{NN } }=200 GeV as a function of transverse and longitudinal momenta
No full textIn 2015 the PHENIX collaboration at the Relativistic Heavy Ion Collider recorded +, +Al, and +Au collision data at center of mass energies of √=200 GeV with the proton beam(s) transversely polarized. At very forward rapidities >6.8 relative to the polarized proton beam, neutrons were detected either inclusively or in (anti)correlation with detector activity related to hard collisions. The resulting single spin asymmetries, that were previously reported, have now been extracted as a function of the transverse momentum of the neutron as well as its longitudinal momentum fraction . The explicit kinematic dependence, combined with the correlation information allows for a closer look at the interplay of different mechanisms suggested to describe these asymmetries, such as hadronic interactions or electromagnetic interactions in ultraperipheral collisions, UPC. Events that are correlated with a hard collision indeed display a mostly negative asymmetry that increases in magnitude as a function of transverse momentum with only little dependence on . In contrast, events that are not likely to have emerged from a hard collision display positive asymmetries for the nuclear collisions with a kinematic dependence that resembles that of a UPC based model. Because the UPC interaction depends strongly on the charge of the nucleus, those effects are very small for + collisions, moderate for +Al collisions, and large for +Au collisions.【The members of PHENIX Collaboration not shown at the author section】
U. A. Acharya, C. Aidala, Y. Akiba, M. Alfred, V. Andrieux, N. Apadula, H. Asano, B. Azmoun, V. Babintsev, N. S. Bandara, K. N. Barish, S. Bathe, A. Bazilevsky, M. Beaumier, R. Belmont, A. Berdnikov, Y. Berdnikov, L. Bichon, B. Blankenship, D. S. Blau, J. S. Bok, V. Borisov, M. L. Brooks, J. Bryslawskyj, V. Bumazhnov, S. Campbell, V. Canoa Roman, R. Cervantes, M. Chiu, C.Y. Chi, I.J. Choi, J.B. Choi, Citron, M. Connors, R. Corliss, N. Cronin, T. Csörgő, M. Csanád, T. W. Danley, M. S. Daugherity, G. David, K. DeBlasio, K. Dehmelt, A. Denisov, A. Deshpande, E. J. Desmond, A. Dion, D. Dixit, J. H. Do, A. Drees, K. A. Drees, J. M. Durham, A. Durum, H. En'yo, A. Enokizono, R. Esha, S. Esumi, B. Fadem, W. Fan, N. Feege, D.E. Fields, M. Finger, Jr., M. Finger, D. Fitzgerald, S. L. Fokin, J. E. Frantz, A. Franz, A. D. Frawley, Y. Fukuda, P. Gallus, C. Gal, P. Garg, H. Ge, M. Giles, F. Giordano, Y. Goto, N. Grau, S.V. Greene, M. Grosse Perdekamp, T. Gunji, H. Guragain, T. Hachiya, J. S. Haggerty, K. I. Hahn, H. Hamagaki, H.F. Hamilton, J. Hanks, S. Y. Han, M. Harvey, S. Hasegawa, T. O. S. Haseler, T. K. Hemmick, X. He, J.C. Hill, K. Hill,11 A. Hodges, R.S. Hollis, K. Homma, B. Hong, T. Hoshino, N. Hotvedt, J. Huang, K. Imai, M. Inaba, A. Iordanova, D. Isenhower, D. Ivanishchev, B. V. Jacak, M. Jezghani, X. Jiang, Z. Ji, B. M. Johnson , D. Jouan, D. S. Jumper, J. H. Kang, D. Kapukchyan, S. Karthas, D. Kawall, A. V. Kazantsev, V. Khachatryan, A. Khanzadeev, A. Khatiwada, C. Kim, E.-J. Kim, M. Kim, T. Kim, D. Kincses, A. Kingan, E. Kistenev, J. Klatsky, P. Kline, T. Koblesky, D. Kotov, L. Kovacs, Kudo, K. Kurita, Y. Kwon, J. G. Lajoie, D. Larionova, A. Lebedev, S. Lee, S. H. Lee, M.J. Leitch, Y. H. Leung, N.A. Lewis, S.H. Lim, M. X. Liu, X. Li, V.-R. Loggins, D.A. Loomis, K. Lovasz, Lynch, S. Lökös, T. Majoros, Y. I. Makdisi, M. Makek, V. I. Manko, E. Mannel, M. McCumber, P. L. McGaughey, D. McGlinchey, C. McKinney, M. Mendoza, A.C. Mignerey, A. Milov, D.K. Mishra, J. T. Mitchell, M. Mitrankova, Iu. Mitrankov, G. Mitsuka, S. Miyasaka, S. Mizuno, M. M. Mondal, P. Montuenga, T. Moon, D. P. Morrison, B. Mulilo, T. Murakami, J. Murata, K. Nagai, K. Nagashima, T. Nagashima, J. L. Nagle, M.I. Nagy, I. Nakagawa, K. Nakano, C. Nattrass, S. Nelson, T. Niida, R. Nouicer, T. Novák, N. Novitzky, G. Nukazuka, A. S. Nyanin, E. O’Brien, C. A. Ogilvie, J. D. Orjuela Koop, J. D. Osborn, A. Oskarsson, G. J. Ottino, K. Ozawa, V. Pantuev, V. Papavassiliou, J. S. Park, S. Park, M. Patel, S. F. Pate, W. Peng, D. V. Perepelitsa, G. D. N. Perera, D. Yu. Peressounko, C. E. PerezLara, J. Perry, R. Petti, M. Phipps, C. Pinkenburg, R. P. Pisani, M. Potekhin, A. Pun, M.L. Purschke, P. V. Radzevich, N. Ramasubramanian, K. F. Read, D. Reynolds, V. Riabov, Y. Riabov, D. Richford, T. Rinn, S. D. Rolnick, M. Rosati, Z. Rowan, J. Runchey, A. S. Safonov, T. Sakaguchi, H. Sako, V. Samsonov, M. Sarsour, S. Sato, B. Schaefer, B. K. Schmoll, K. Sedgwick, R. Seidl, A. Sen, R. Seto, A. Sexton, D. Sharma, I. Shein, T.-A. Shibata, K. Shigaki, M. Shimomura, T. Shioya, P. Shukla, A. Sickles, C. L. Silva, D. Silvermyr, B. K. Singh, C. P. Singh, V. Singh, M. Slunečka, K.L. Smith, M. Snowball, R.A. Soltz, W.E. Sondheim, S.P. Sorensen, I. V. Sourikova, P. W. Stankus, S. P. Stoll, T. Sugitate, A. Sukhanov, T. Sumita, J. Sun, Z. Sun, J. Sziklai, K. Tanida, M. J. Tannenbaum, S. Tarafdar, A. Taranenko, G. Tarnai, R. Tieulent, A. Timilsina, T. Todoroki, M. Tomášek, C. L. Towell, R.S. Towell, I. Tserruya, Y. Ueda, B. Ujvari, H. W. van Hecke, J. Velkovska, M. Virius, V. Vrba, N. Vukman, X. R. Wang, Y. S. Watanabe, C. P. Wong, C. L. Woody, L. Xue, C. Xu, Q. Xu, S. Yalcin, Y. L. Yamaguchi, H. Yamamoto, A. Yanovich, I. Yoon, J. H. Yoo, I.E. Yushmanov, H. Yu, W.A. Zajc, A. Zelenski, S. Zharko, and L. Zoujournal articl
Nuclear Dependence of the Transverse Single-Spin Asymmetry in the Production of Charged Hadrons at Forward Rapidity in Polarized p+p, p+Al, and p+Au Collisions at sNN =200 GeV
No full text© 2019 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article\u27s title, journal citation, and DOI. Funded by SCOAP 3 . We report on the nuclear dependence of transverse single-spin asymmetries (TSSAs) in the production of positively charged hadrons in polarized p↑+p, p↑+Al, and p↑+Au collisions at sNN=200 GeV. The measurements have been performed at forward rapidity (1.4\u3cη\u3c2.4) over the range of transverse momentum (1.
J/ψ elliptic flow in Pb-Pb collisions at TeV
No full textWe report on the first measurement of inclusive J/psi elliptic flow v(2) in heavy-ion collisions at the LHC. The measurement is performed with the ALICE detector in Pb-Pb collisions at root s(NN) = 2.76 TeV in the rapidity range 2.5 < y < 4.0. The dependence of the J/psi v(2) on the collision centrality and on the J/psi transverse momentum is studied in the range 0 <= p(T) < 10 GeV/c. For semicentral Pb-Pb collisions at root s(NN) = 2.76 TeV, an indication of nonzero v(2) is observed with a largest measured value of v(2) = 0.116 +/-0.046(stat) +/- 0.029(syst) for J/psi in the transverse momentum range 2 <= p(T) < 4 GeV/c. The elliptic flow measurement complements the previously reported ALICE results on the inclusive J/psi nuclear modification factor and favors the scenario of a significant fraction of J/psi production from charm quarks in a deconfined partonic phase
Nuclear-modification factor of charged hadrons at forward and backward rapidity in p + Al and p + Au collisions at sNN =200 GeV
No full text© 2020 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article\u27s title, journal citation, and DOI. Funded by SCOAP 3 . The PHENIX experiment has studied nuclear effects in p+Al and p+Au collisions at sNN=200GeV on charged hadron production at forward rapidity (1.4\u3cη\u3c2.4, p-going direction) and backward rapidity (-2.2\u3cη\u3c-1.2, A-going direction). Such effects are quantified by measuring nuclear modification factors as a function of transverse momentum and pseudorapidity in various collision multiplicity selections. In central p+Al and p+Au collisions, a suppression (enhancement) is observed at forward (backward) rapidity compared to the binary scaled yields in p+p collisions. The magnitude of enhancement at backward rapidity is larger in p+Au collisions than in p+Al collisions, which have a smaller number of participating nucleons. However, the results at forward rapidity show a similar suppression within uncertainties. The results in the integrated centrality are compared with calculations using nuclear parton distribution functions, which show a reasonable agreement at the forward rapidity but fail to describe the backward rapidity enhancement
Long-range angular correlations of π, K and p in p–Pb collisions at
No full textAngular correlations between unidentified charged trigger particles and various species of charged associated particles (unidentified particles, pions, kaons, protons and antiprotons) are measured by the ALICE detector in p-Pb collisions at a nucleon-nucleon centre-of-mass energy of 5.02 TeV in the transverse-momentum range 0.3 < p(T) < 4 GeV/c. The correlations expressed as associated yield per trigger particle are obtained in the pseudorapidity range vertical bar n(lab)vertical bar < 0.8. Fourier coefficients are extracted from the long-range correlations projected onto the azimuthal angle difference and studied as a function of p(T) and in intervals of event multiplicity. In high-multiplicity events, the second-order coefficient for protons, 4, is observed to be smaller than that for pions, v(2)(pi), up to about p(T) = 2 GeV/c. To reduce correlations due to jets, the per-trigger yield measured in low-multiplicity events is subtracted from that in high-multiplicity events. A two-ridge structure is obtained for all particle species. The Fourier decomposition of this structure shows that the second-order coefficients for pions and kaons are similar. The v(2)(p) is found to be smaller at low P-T and larger at higher p(T) than v(2)(pi), with a crossing occurring at about 2 GeV/c. This is qualitatively similar to the elliptic-flow pattern observed in heavy-ion collisions. A mass ordering effect at low transverse momenta is consistent with expectations from hydrodynamic model calculations assuming a collectively expanding system. (C) 2013 CERN. Published by Elsevier B.V. All rights reserved
Elliptic Flow of Charged Particles in Pb-Pb Collisions at root s(NN)=2.76 TeV
No full textWe report the first measurement of charged particle elliptic flow in Pb-Pb collisions at root s(NN) p = 2.76 TeV with the ALICE detector at the CERN Large Hadron Collider. The measurement is performed in the central pseudorapidity region (vertical bar eta vertical bar \u3c 0.8) and transverse momentum range 0.2 \u3c p(t) \u3c 5.0 GeV/c. The elliptic flow signal v(2), measured using the 4-particle correlation method, averaged over transverse momentum and pseudorapidity is 0.087 +/- 0.002(stat) +/- 0.003(syst) in the 40%-50% centrality class. The differential elliptic flow v(2)(p(t)) reaches a maximum of 0.2 near p(t) = 3 GeV/c. Compared to RHIC Au-Au collisions at root s(NN) = 200 GeV, the elliptic flow increases by about 30%. Some hydrodynamic model predictions which include viscous corrections are in agreement with the observed increase
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