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Surface analysis of single-crystalline β - FeSi 2

physics Procedia 2011年 11卷 67-70页

作者： Yoichi Yamada Wei Mao Hidehito Asaoka Hiroyuki Yamamoto Fumitaka Esaka Haruhiko Udonob Tomohito Tsurud University of Tsukuba Institute of Applied Physics Tsukuba Ibaraki 305-8501 Japan IbarakUniversityi Graduate School of Science and Engineering Hitachi Ibaraki 316-0033 Japan Japan Atomic Energy Agency Quantum Beam Science Directorate Tokai Ibaraki 319-1195 Japan Japan Atomic Energy Agency Nuclear Science and Engineering Directorate Tokai Ibaraki 319-1195 Japan

Clean surfaces of the single crystalline β - FeSi 2 have been prepared and investigated by means of surface analysis techniques. X-ray photoelectron spectroscopy of the surface oxide reveals that the surface Si is mainly oxidized while Fe isn’t. After removing the surface oxide, clean surface can be obtained showing well-defined atomic features in low-energy electron diffraction and scanning tunneling microscopy. No drastic surface reconstruction is found possibly reflecting strong Fe–Si bond. Density functional theory calculation suggests the spin polarized surface electronic density of states when Fe comes at the surface, although such a situation seems to be unlikely.

关键词： β - FeSi 2 Surface spin polarization

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Ferroelectricity and ferromagnetism in EuTiO3 nanowires

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Physical Review B 2011年第20期84卷 205403-205403页

作者： Anna N. Morozovska Maya D. Glinchuk Rakesh K. Behera Basil Zaulychny Chaitanya S. Deo Eugene A. Eliseev Institute for Problems of Materials Science NAS of Ukraine Krjijanovskogo 3 03142 Kiev Ukraine V. Lashkaryov Institute of Semiconductor Physics NAS of Ukraine pr. Nauki 41 03028 Kiev Ukraine Nuclear and Radiological Engineering Program George W. Woodruff School of Mechanical Engineering Georgia Institute of Technology Atlanta Georgia 30332 USA

We predicted the ferroelectric–ferromagnetic multiferroic properties of EuTiO3 nanowires and generated the phase diagrams in coordinates of temperature and wire radii. The calculations were performed within the Landau-Ginzburg-Devonshire theory with phenomenological parameters extracted from tabulated experimental data and first-principles calculations. Since bulk EuTiO3 is antiferromagnetic at temperatures lower than 5.5 K and paraelectric at all temperatures, our goal was to investigate the possibility of inducing the ferroelectric and ferromagnetic properties of EuTiO3 by reducing the bulk to nanosystems. Our results indicate that ferroelectric spontaneous polarization of ∼0.1–0.5 C/m2 is induced in EuTiO3 nanowires due to the intrinsic surface stress, which is inversely proportional to the nanowire radius. Spontaneous polarization exists at temperatures lower than 300 K for wire diameter of ∼4 lattice constants with 10 N/m surface stress coefficient. Due to the strong biquadratic magnetoelectric coupling, the spontaneous polarization in turn induces the ferromagnetic phase at temperatures lower than 30 K for 2-nm nanowire and at temperatures lower than 10 K for 4-nm nanowire in EuTiO3. Thus, we predicted that the EuTiO3 nanowires can be the new ferroelectric–ferromagnetic multiferroic.

关键词： FERROELECTRICITY LANDAU levels NANOWIRES MAGNETIC couplings LATTICE theory FERROMAGNETISM

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Fabrication of uniform QPM device using negative multiple pulse poling method

Fabrication of uniform QPM device using negative multiple pu...

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International Conference on Quantum Electronics (IQEC)

作者： Ju Won Choi Heejong Kang Do-Kyeong Ko Jung Hoon Ro Nan Ei Yu Graduate program of Photonics and Applied Physics Gwangju Institute of Science and Technology Gwangju South Korea Advanced Photonics Research Institute Gwangju Institute of Science and Technology Gwangju South Korea Department of Biomedical Engineering School of Medicine Pusan National University Busan South Korea

We introduced a novel negative multiple pulse poling (NMP) method for uniform device fabrication of quasi-phase matching using an in-situ visualization system. Diffraction pattern analysis showed the duty ratio of 0.4... 详细信息

ISBN: (纸本)9780977565771

关键词： Diffraction Lithium niobate Visualization Crystals Optical diffraction Resists Real time systems

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Effect of final state interactions on particle production in d+Au collisions at energies available at the BNL Relativistic Heavy Ion Collider

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Physical Review C 2011年第3期84卷 031901(R)-031901(R)页

作者： Xiaoping Zhang Jinhui Chen Zhongzhou Ren N. Xu Zhangbu Xu Qiang Zheng Xianglei Zhu Department of Physics Nanjing University Nanjing 210008 China Nuclear Science Division Lawrence Berkeley National Laboratory Berkeley California 94720 USA Department of Engineering Physics Tsinghua University Beijing 100084 China Shanghai Institute of Applied Physics CAS Shanghai 201800 China Brookhaven National Laboratory Upton New York 11973 USA School of Mathematics and Computer Science Guizhou Normal University Guiyang 550001 China

We show that particle species dependence of enhanced hadron production at intermediate transverse momentum (pT) for d+Au collisions at RHIC can be understood in terms of the hadronization from string fragmentation and the subsequent hadronic rescatterings in the final state. A multiphase transport model (AMPT) with two different hadronization mechanisms, string fragmentation or parton coalescence, is used in our study. When the hadrons are formed from string fragmentation, the subsequent hadronic rescatterings will result in particle mass dependence of the nuclear modification factor RCP, which is consistent with the present experimental data. On the other hand, in the framework of parton coalescence, the mass dependence disappears and the strangeness plays an important role in hadron production.

关键词： HEAVY ions RELATIVISTIC kinematics HEAVY ion collisions HADRON colliders PARTICLES (nuclear physics)

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Cold-nuclear-Matter Effects on Heavy-Quark Production in d+Au Collisions at sNN=200 GeV

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Physical Review Letters 2012年第24期109卷 242301-242301页

作者： A. Adare C. Aidala N. N. Ajitanand Y. Akiba H. Al-Bataineh J. Alexander A. Angerami K. Aoki N. Apadula Y. Aramaki E. T. Atomssa R. Averbeck T. C. Awes B. Azmoun V. Babintsev M. Bai G. Baksay L. Baksay K. N. Barish B. Bassalleck A. T. Basye S. Bathe V. Baublis C. Baumann A. Bazilevsky S. Belikov R. Belmont R. Bennett A. Berdnikov Y. Berdnikov J. H. Bhom D. S. Blau J. S. Bok K. Boyle M. L. Brooks H. Buesching V. Bumazhnov G. Bunce S. Butsyk S. Campbell A. Caringi C.-H. Chen C. Y. Chi M. Chiu I. J. Choi J. B. Choi R. K. Choudhury P. Christiansen T. Chujo P. Chung O. Chvala V. Cianciolo Z. Citron B. A. Cole Z. Conesa del Valle M. Connors M. Csanád T. Csörgő T. Dahms S. Dairaku I. Danchev K. Das A. Datta G. David M. K. Dayananda A. Denisov A. Deshpande E. J. Desmond K. V. Dharmawardane O. Dietzsch A. Dion M. Donadelli O. Drapier A. Drees K. A. Drees J. M. Durham A. Durum D. Dutta L. D’Orazio S. Edwards Y. V. Efremenko F. Ellinghaus T. Engelmore A. Enokizono H. En’yo S. Esumi B. Fadem D. E. Fields M. Finger M. Finger, Jr. F. Fleuret S. L. Fokin Z. Fraenkel J. E. Frantz A. Franz A. D. Frawley K. Fujiwara Y. Fukao T. Fusayasu I. Garishvili A. Glenn H. Gong M. Gonin Y. Goto R. Granier de Cassagnac N. Grau S. V. Greene G. Grim M. Grosse Perdekamp T. Gunji H.-Å. Gustafsson J. S. Haggerty K. I. Hahn H. Hamagaki J. Hamblen R. Han J. Hanks E. Haslum R. Hayano X. He M. Heffner T. K. Hemmick T. Hester J. C. Hill M. Hohlmann W. Holzmann K. Homma B. Hong T. Horaguchi D. Hornback S. Huang T. Ichihara R. Ichimiya Y. Ikeda K. Imai M. Inaba D. Isenhower M. Ishihara M. Issah D. Ivanischev Y. Iwanaga B. V. Jacak J. Jia X. Jiang J. Jin B. M. Johnson T. Jones K. S. Joo D. Jouan D. S. Jumper F. Kajihara J. Kamin J. H. Kang J. Kapustinsky K. Karatsu M. Kasai D. Kawall M. Kawashima A. V. Kazantsev T. Kempel A. Khanzadeev K. M. Kijima J. Kikuchi A. Kim B. I. Kim D. J. Kim E.-J. Kim Y.-J. Kim E. Kinney Á. Kiss E. Kistenev D. Kleinjan L. Kochenda B. Komkov M. Konno J. Koster A. Král A. Kravitz G. J. Kunde K. Kurita M. Kurosawa Y. Kwon G. S. Kyl University of Colorado Boulder Colorado 80309 USA Department of Physics University of Massachusetts Amherst Massachusetts 01003-9337 USA Chemistry Department Stony Brook University SUNY Stony Brook New York 11794-3400 USA RIKEN Nishina Center for Accelerator-Based Science Wako Saitama 351-0198 Japan RIKEN BNL Research Center Brookhaven National Laboratory Upton New York 11973-5000 USA New Mexico State University Las Cruces New Mexico 88003 USA Columbia University New York New York 10027 and Nevis Laboratories Irvington New York 10533 USA Kyoto University Kyoto 606-8502 Japan Department of Physics and Astronomy Stony Brook University SUNY Stony Brook New York 11794-3400 USA Center for Nuclear Study Graduate School of Science University of Tokyo 7-3-1 Hongo Bunkyo Tokyo 113-0033 Japan Laboratoire Leprince-Ringuet Ecole Polytechnique CNRS-IN2P3 Route de Saclay F-91128 Palaiseau France Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA Physics Department Brookhaven National Laboratory Upton New York 11973-5000 USA IHEP Protvino State Research Center of Russian Federation Institute for High Energy Physics Protvino 142281 Russia Collider-Accelerator Department Brookhaven National Laboratory Upton New York 11973-5000 USA Florida Institute of Technology Melbourne Florida 32901 USA University of California—Riverside Riverside California 92521 USA University of New Mexico Albuquerque New Mexico 87131 USA Abilene Christian University Abilene Texas 79699 USA PNPI Petersburg Nuclear Physics Institute Gatchina Leningrad region 188300 Russia Institut fur Kernphysik University of Muenster D-48149 Muenster Germany Vanderbilt University Nashville Tennessee 37235 USA Saint Petersburg State Polytechnic University St. Petersburg 195251 Russia Yonsei University IPAP Seoul 120-749 Korea Russian Research Center “Kurchatov Institute” Moscow 123098 Russia Los Alamos National Laboratory Los Alamos New Mexico 87545 USA Muhlenberg College

The PHENIX experiment has measured electrons and positrons at midrapidity from the decays of hadrons containing charm and bottom quarks produced in d+Au and p+p collisions at sNN=200 GeV in the transverse-momentum range 0.85≤pTe≤8.5 GeV/c. In central d+Au collisions, the nuclear modification factor RdA at 1.5nuclear-matter effects on light- and heavy-flavor mesons could contribute to the observed differences between the π0 and heavy-flavor-electron nuclear modification factors RAA.

关键词： ELECTRONS POSITRONS HADRONS QUARKS COLLISIONS (physics)

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Development of continuous wrapping tantalum barriers for internal-tin Nb3Sn multi-filamentary wires

Development of continuous wrapping tantalum barriers for int...

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International Conference on applied Superconductivity and Electromagnetic Devices, ASEMD

作者： Wu Ming Chen Mustafa Yavuz Xue Kui Fu Shiro Kambe Peter McIntyre Jian Xun Jin Waterloo Institute for Nanotechnology University of Waterloo Waterloo ONT Canada School of Materials Science & Engineering University of New South Wales Sydney NSW Australia Human Sensing Program Graduate School of Science and Engineering Yamagata University Yonezawa Japan Waterloo Institute for Nanotechnology University of Waterloo Cankaya University Ankara ON Turkey Department of Physics Texas A&M University TX USA Center of Applied Superconductivity and Electrical Engineering University of Electronic Science and Technology of China China

A process, continuous wrapping tantalum barrier, has been developed and investigated in order to reduce the manufacturing cost. By avoiding inserting expensive tantalum tube, a long sheet barrier was directly used to wrap a prior restack. In this work, a tantalum barrier with 20 % overlap was wrapped onto sub-elements. Then 18-filament Nb 3 Sn plus 1 copper core restack billet was successfully drawn down and extruded into round wire as thin as a diameter of 0.84 mm. The longitudinal and cross-sectional images revealed most of barriers were continuous and intact. However, further experiments are needed to optimize the process in order to keep the all barriers continuous and intact after manufacturing.

关键词： Niobium-tin Wires Copper Electron tubes Educational institutions Superconducting magnets

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Highly sensitive temperature sensor based on the side-hole optical fiber filled with indium

Highly sensitive temperature sensor based on the side-hole o...

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European Conference on Optical Communication (ECOC)

作者： B. H. Kim S. H. Lee D. H. Son T.-J. Ahn S. Kim W.-T. Han Advanced Photonics Research Institute Gwangju Institute of Science and Technology Gwangju South Korea Graduate Program of Photonics and Applied Physics School of Information and Communications GIST Gwangju South Korea Department Photonic Engineering Chosun University Gwangju South Korea

A highly sensitive temperature sensor based on a side-hole fiber filled with indium was proposed and its optical characteristics were experimentally demonstrated. The temperature sensitivity of the sensor was estimate... 详细信息

ISBN: (纸本)9781557529312

关键词： Optical fiber sensors Optical fiber polarization Temperature sensors Indium Sensitivity

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Observation of Direct-Photon Collective Flow in Au+Au Collisions at sNN=200 GeV

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Physical Review Letters 2012年第12期109卷 122302-122302页

作者： A. Adare S. Afanasiev C. Aidala N. N. Ajitanand Y. Akiba H. Al-Bataineh J. Alexander K. Aoki Y. Aramaki E. T. Atomssa R. Averbeck T. C. Awes B. Azmoun V. Babintsev M. Bai G. Baksay L. Baksay K. N. Barish B. Bassalleck A. T. Basye S. Bathe V. Baublis C. Baumann A. Bazilevsky S. Belikov R. Belmont R. Bennett A. Berdnikov Y. Berdnikov A. A. Bickley J. S. Bok K. Boyle M. L. Brooks H. Buesching V. Bumazhnov G. Bunce S. Butsyk C. M. Camacho S. Campbell C.-H. Chen C. Y. Chi M. Chiu I. J. Choi R. K. Choudhury P. Christiansen T. Chujo P. Chung O. Chvala V. Cianciolo Z. Citron B. A. Cole M. Connors P. Constantin M. Csanád T. Csörgő T. Dahms S. Dairaku I. Danchev K. Das A. Datta G. David A. Denisov A. Deshpande E. J. Desmond O. Dietzsch A. Dion M. Donadelli O. Drapier A. Drees K. A. Drees J. M. Durham A. Durum D. Dutta S. Edwards Y. V. Efremenko F. Ellinghaus T. Engelmore A. Enokizono H. En’yo S. Esumi B. Fadem D. E. Fields M. Finger M. Finger, Jr. F. Fleuret S. L. Fokin Z. Fraenkel J. E. Frantz A. Franz A. D. Frawley K. Fujiwara Y. Fukao T. Fusayasu I. Garishvili A. Glenn H. Gong M. Gonin Y. Goto R. Granier de Cassagnac N. Grau S. V. Greene M. Grosse Perdekamp T. Gunji H.-Å. Gustafsson J. S. Haggerty K. I. Hahn H. Hamagaki J. Hamblen R. Han J. Hanks E. P. Hartouni E. Haslum R. Hayano X. He M. Heffner T. K. Hemmick T. Hester J. C. Hill M. Hohlmann W. Holzmann K. Homma B. Hong T. Horaguchi D. Hornback S. Huang T. Ichihara R. Ichimiya J. Ide Y. Ikeda K. Imai M. Inaba D. Isenhower M. Ishihara T. Isobe M. Issah A. Isupov D. Ivanischev B. V. Jacak J. Jia J. Jin B. M. Johnson K. S. Joo D. Jouan D. S. Jumper F. Kajihara S. Kametani N. Kamihara J. Kamin J. H. Kang J. Kapustinsky K. Karatsu D. Kawall M. Kawashima A. V. Kazantsev T. Kempel A. Khanzadeev K. M. Kijima B. I. Kim D. H. Kim D. J. Kim E. Kim E. J. Kim S. H. Kim Y. J. Kim E. Kinney K. Kiriluk Á. Kiss E. Kistenev C. Klein-Boesing L. Kochenda B. Komkov M. Konno J. Koster D. Kotchetkov A. Kozlov A. Král A. Kravitz G. J. Kunde K. Kurita M. Kurosawa Y. Kwon G. S. Kyle R. Lacey Y University of Colorado Boulder Colorado 80309 USA Joint Institute for Nuclear Research 141980 Dubna Moscow Region Russia Department of Physics University of Massachusetts Amherst Massachusetts 01003-9337 USA Chemistry Department Stony Brook University SUNY Stony Brook New York 11794-3400 USA RIKEN Nishina Center for Accelerator-Based Science Wako Saitama 351-0198 Japan RIKEN BNL Research Center Brookhaven National Laboratory Upton New York 11973-5000 USA New Mexico State University Las Cruces New Mexico 88003 USA Kyoto University Kyoto 606-8502 Japan Center for Nuclear Study Graduate School of Science University of Tokyo 7-3-1 Hongo Bunkyo Tokyo 113-0033 Japan Laboratoire Leprince-Ringuet Ecole Polytechnique CNRS-IN2P3 Route de Saclay F-91128 Palaiseau France Department of Physics and Astronomy Stony Brook University SUNY Stony Brook New York 11794-3400 USA Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA Physics Department Brookhaven National Laboratory Upton New York 11973-5000 USA IHEP Protvino State Research Center of Russian Federation Institute for High Energy Physics Protvino 142281 Russia Collider-Accelerator Department Brookhaven National Laboratory Upton New York 11973-5000 USA Florida Institute of Technology Melbourne Florida 32901 USA University of California-Riverside Riverside California 92521 USA University of New Mexico Albuquerque New Mexico 87131 USA Abilene Christian University Abilene Texas 79699 USA PNPI Petersburg Nuclear Physics Institute Gatchina Leningrad region 188300 Russia Institut fur Kernphysik University of Muenster D-48149 Muenster Germany Vanderbilt University Nashville Tennessee 37235 USA Saint Petersburg State Polytechnic University St. Petersburg 195251 Russia Yonsei University IPAP Seoul 120-749 Korea Los Alamos National Laboratory Los Alamos New Mexico 87545 USA Columbia University New York New York 10027 and Nevis Laboratories Irvington New York 10533 USA Bhabha Atomic

The second Fourier component v2 of the azimuthal anisotropy with respect to the reaction plane is measured for direct photons at midrapidity and transverse momentum (pT) of 1–12 GeV/c in Au+Au collisions at sNN=200 GeV. Previous measurements of this quantity for hadrons with pT<6 GeV/c indicate that the medium behaves like a nearly perfect fluid, while for pT>6 GeV/c a reduced anisotropy is interpreted in terms of a path-length dependence for parton energy loss. In this measurement with the PHENIX detector at the Relativistic Heavy Ion Collider we find that for pT>4 GeV/c the anisotropy for direct photons is consistent with zero, which is as expected if the dominant source of direct photons is initial hard scattering. However, in the pT<4 GeV/c region dominated by thermal photons, we find a substantial direct-photon v2 comparable to that of hadrons, whereas model calculations for thermal photons in this kinematic region underpredict the observed v2.

关键词： HEAVY ion collisions PHOTONS OBSERVATION (Scientific method) ANISOTROPY FOURIER analysis HADRONS MOMENTUM (Mechanics) nuclear models

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Measurement of Direct Photons in Au+Au Collisions at sNN=200 GeV

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Physical Review Letters 2012年第15期109卷 152302-152302页

作者： S. Afanasiev C. Aidala N. N. Ajitanand Y. Akiba A. Al-Jamel J. Alexander K. Aoki L. Aphecetche R. Armendariz S. H. Aronson R. Averbeck T. C. Awes B. Azmoun V. Babintsev A. Baldisseri K. N. Barish P. D. Barnes B. Bassalleck S. Bathe S. Batsouli V. Baublis F. Bauer A. Bazilevsky S. Belikov R. Bennett Y. Berdnikov M. T. Bjorndal J. G. Boissevain H. Borel K. Boyle M. L. Brooks D. S. Brown D. Bucher H. Buesching V. Bumazhnov G. Bunce J. M. Burward-Hoy S. Butsyk S. Campbell J.-S. Chai S. Chernichenko C. Y. Chi J. Chiba M. Chiu I. J. Choi T. Chujo V. Cianciolo C. R. Cleven Y. Cobigo B. A. Cole M. P. Comets M. Connors P. Constantin M. Csanád T. Csörgő T. Dahms K. Das G. David H. Delagrange A. Denisov D. d’Enterria A. Deshpande E. J. Desmond O. Dietzsch A. Dion J. L. Drachenberg O. Drapier A. Drees A. K. Dubey A. Durum V. Dzhordzhadze Y. V. Efremenko J. Egdemir A. Enokizono H. En’yo B. Espagnon S. Esumi D. E. Fields F. Fleuret S. L. Fokin B. Forestier Z. Fraenkel J. E. Frantz A. Franz A. D. Frawley Y. Fukao S.-Y. Fung S. Gadrat F. Gastineau M. Germain A. Glenn M. Gonin J. Gosset Y. Goto R. Granier de Cassagnac N. Grau S. V. Greene M. Grosse Perdekamp T. Gunji H.-Å. Gustafsson T. Hachiya A. Hadj Henni J. S. Haggerty M. N. Hagiwara H. Hamagaki H. Harada E. P. Hartouni K. Haruna M. Harvey E. Haslum K. Hasuko R. Hayano X. He M. Heffner T. K. Hemmick J. M. Heuser H. Hiejima J. C. Hill R. Hobbs M. Holmes W. Holzmann K. Homma B. Hong T. Horaguchi M. G. Hur T. Ichihara H. Iinuma K. Imai J. Imrek M. Inaba D. Isenhower L. Isenhower M. Ishihara T. Isobe M. Issah A. Isupov B. V. Jacak J. Jia J. Jin O. Jinnouchi B. M. Johnson K. S. Joo D. Jouan F. Kajihara S. Kametani N. Kamihara M. Kaneta J. H. Kang T. Kawagishi A. V. Kazantsev S. Kelly A. Khanzadeev D. J. Kim E. Kim Y.-S. Kim E. Kinney Á. Kiss E. Kistenev A. Kiyomichi C. Klein-Boesing L. Kochenda V. Kochetkov B. Komkov M. Konno D. Kotchetkov A. Kozlov P. J. Kroon G. J. Kunde N. Kurihara K. Kurita M. J. Kweon Y. Kwon G. S. Kyle R. Lacey J. G. Lajoie A. Lebedev Y. Le Bornec S. Leckey Joint Institute for Nuclear Research 141980 Dubna Moscow Region Russia Columbia University New York New York 10027 and Nevis Laboratories Irvington New York 10533 USA Chemistry Department Stony Brook University SUNY Stony Brook New York 11794-3400 USA RIKEN Nishina Center for Accelerator-Based Science Wako Saitama 351-0198 Japan RIKEN BNL Research Center Brookhaven National Laboratory Upton New York 11973-5000 USA New Mexico State University Las Cruces New Mexico 88003 USA Kyoto University Kyoto 606-8502 Japan SUBATECH (Ecole des Mines de Nantes CNRS-IN2P3 Université de Nantes) BP 20722-44307 Nantes France Brookhaven National Laboratory Upton New York 11973-5000 USA Department of Physics and Astronomy Stony Brook University SUNY Stony Brook New York 11794-3400 USA Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA IHEP Protvino State Research Center of Russian Federation Institute for High Energy Physics Protvino 142281 Russia Dapnia CEA Saclay F-91191 Gif-sur-Yvette France University of California-Riverside Riverside California 92521 USA Los Alamos National Laboratory Los Alamos New Mexico 87545 USA University of New Mexico Albuquerque New Mexico 87131 USA PNPI Petersburg Nuclear Physics Institute Gatchina Leningrad region 188300 Russia Iowa State University Ames Iowa 50011 USA Saint Petersburg State Polytechnic University St. Petersburg 195251 Russia Institut für Kernphysik University of Muenster D-48149 Muenster Germany KAERI Cyclotron Application Laboratory Seoul Korea KEK High Energy Accelerator Research Organization Tsukuba Ibaraki 305-0801 Japan Yonsei University IPAP Seoul 120-749 Korea Vanderbilt University Nashville Tennessee 37235 USA Georgia State University Atlanta Georgia 30303 USA IPN-Orsay Universite Paris Sud CNRS-IN2P3 BP1 F-91406 Orsay France ELTE Eötvös Loránd University H-1117 Budapest Pázmány P. s. 1/A Hungary Institute for Particle and Nuclear Physics Wigner Research Centre for Physics

We report the measurement of direct photons at midrapidity in Au+Au collisions at sNN=200 GeV. The direct photon signal was extracted for the transverse momentum range of 4 GeV/cnuclear modification factor RAA was calculated as a function of pT for different Au+Au collision centralities using the measured p+p direct photon spectrum and compared to theoretical predictions. RAA was found to be consistent with unity for all centralities over the entire measured pT range. Theoretical models that account for modifications of initial direct photon production due to modified parton distribution functions in Au and the different isospin composition of the nuclei predict a modest change of RAA from unity. They are consistent with the data. Models with compensating effects of the quark-gluon plasma on high-energy photons, such as suppression of jet-fragmentation photons and induced-photon bremsstrahlung from partons traversing the medium, are also consistent with this measurement.

关键词： PHYSICAL measurements HEAVY ion collisions PHOTONS ANGULAR momentum (nuclear physics) PREDICTION models ANGULAR distribution (nuclear physics) QUARK-gluon plasma

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Deviation from quark number scaling of the anisotropy parameter v2 of pions, kaons, and protons in Au+Au collisions at sNN=200 GeV

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Physical Review C 2012年第6期85卷 064914-064914页

作者： A. Adare S. Afanasiev C. Aidala N. N. Ajitanand Y. Akiba H. Al-Bataineh J. Alexander K. Aoki Y. Aramaki E. T. Atomssa R. Averbeck T. C. Awes B. Azmoun V. Babintsev M. Bai G. Baksay L. Baksay K. N. Barish B. Bassalleck A. T. Basye S. Bathe V. Baublis C. Baumann A. Bazilevsky S. Belikov R. Belmont R. Bennett A. Berdnikov Y. Berdnikov A. A. Bickley J. S. Bok K. Boyle M. L. Brooks H. Buesching V. Bumazhnov G. Bunce S. Butsyk C. M. Camacho S. Campbell C.-H. Chen C. Y. Chi M. Chiu I. J. Choi R. K. Choudhury P. Christiansen T. Chujo P. Chung O. Chvala V. Cianciolo Z. Citron B. A. Cole M. Connors P. Constantin M. Csanád T. Csörgő T. Dahms S. Dairaku I. Danchev K. Das A. Datta G. David A. Denisov A. Deshpande E. J. Desmond O. Dietzsch A. Dion M. Donadelli O. Drapier A. Drees K. A. Drees J. M. Durham A. Durum D. Dutta S. Edwards Y. V. Efremenko F. Ellinghaus T. Engelmore A. Enokizono H. En'yo S. Esumi B. Fadem D. E. Fields M. Finger M. Finger, Jr. F. Fleuret S. L. Fokin Z. Fraenkel J. E. Frantz A. Franz A. D. Frawley K. Fujiwara Y. Fukao T. Fusayasu I. Garishvili A. Glenn H. Gong M. Gonin Y. Goto R. Granier de Cassagnac N. Grau S. V. Greene M. Grosse Perdekamp T. Gunji H.-Å. Gustafsson J. S. Haggerty K. I. Hahn H. Hamagaki J. Hamblen R. Han J. Hanks E. P. Hartouni E. Haslum R. Hayano X. He M. Heffner T. K. Hemmick T. Hester J. C. Hill M. Hohlmann W. Holzmann K. Homma B. Hong T. Horaguchi D. Hornback S. Huang T. Ichihara R. Ichimiya J. Ide Y. Ikeda K. Imai M. Inaba D. Isenhower M. Ishihara T. Isobe M. Issah A. Isupov D. Ivanischev B. V. Jacak J. Jia J. Jin B. M. Johnson K. S. Joo D. Jouan D. S. Jumper F. Kajihara S. Kametani N. Kamihara J. Kamin J. H. Kang J. Kapustinsky K. Karatsu D. Kawall M. Kawashima A. V. Kazantsev T. Kempel A. Khanzadeev K. M. Kijima B. I. Kim D. H. Kim D. J. Kim E. Kim E. J. Kim S. H. Kim Y. J. Kim E. Kinney K. Kiriluk Á. Kiss E. Kistenev L. Kochenda B. Komkov M. Konno J. Koster D. Kotchetkov A. Kozlov A. Král A. Kravitz G. J. Kunde K. Kurita M. Kurosawa Y. Kwon G. S. Kyle R. Lacey Y. S. Lai J. G. La University of Colorado Boulder Colorado 80309 USA Joint Institute for Nuclear Research 141980 Dubna Moscow Region Russia Department of Physics University of Massachusetts Amherst Massachusetts 01003-9337 USA Chemistry Department Stony Brook University State University of New York Stony Brook New York 11794-3400 USA RIKEN Nishina Center for Accelerator-Based Science Wako Saitama 351-0198 Japan RIKEN BNL Research Center Brookhaven National Laboratory Upton New York 11973-5000 USA New Mexico State University Las Cruces New Mexico 88003 USA Kyoto University Kyoto 606-8502 Japan Center for Nuclear Study Graduate School of Science University of Tokyo 7-3-1 Hongo Bunkyo Tokyo 113-0033 Japan Laboratoire Leprince-Ringuet Ecole Polytechnique CNRS-IN2P3 Route de Saclay F-91128 Palaiseau France Department of Physics and Astronomy Stony Brook University State University of New York Stony Brook New York 11794-3400 USA Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA Physics Department Brookhaven National Laboratory Upton New York 11973-5000 USA IHEP Protvino State Research Center of Russian Federation Institute for High Energy Physics Protvino 142281 Russia Collider-Accelerator Department Brookhaven National Laboratory Upton New York 11973-5000 USA Florida Institute of Technology Melbourne Florida 32901 USA University of California - Riverside Riverside California 92521 USA University of New Mexico Albuquerque New Mexico 87131 USA Abilene Christian University Abilene Texas 79699 USA PNPI Petersburg Nuclear Physics Institute Gatchina Leningrad region 188300 Russia Institut fur Kernphysik University of Muenster D-48149 Muenster Germany Vanderbilt University Nashville Tennessee 37235 USA Saint Petersburg State Polytechnic University St. Petersburg 195251 Russia Institute of Physics and Applied Physics Yonsei University Seoul 120-749 Korea Los Alamos National Laboratory Los Alamos New Mexico 87545 USA Columbia University New York N

Measurements of the anisotropy parameter v2 of identified hadrons (pions, kaons, and protons) as a function of centrality, transverse momentum pT, and transverse kinetic energy KET at midrapidity (|η|<0.35) in Au + Au collisions at sNN=200 GeV are presented. Pions and protons are identified up to pT= 6 GeV/c, and kaons up to pT= 4 GeV/c, by combining information from time-of-flight and aerogel Čerenkov detectors in the PHENIX Experiment. The scaling of v2 with the number of valence quarks (nq) has been studied in different centrality bins as a function of transverse momentum and transverse kinetic energy. A deviation from previously observed quark-number scaling is observed at large values of KET/nq in noncentral Au + Au collisions (20–60%), but this scaling remains valid in central collisions (0–10%).

关键词： Collisions hydrogen ions TRANSVERSE MOMENTUM kaons pi-Mesons Deviation Quarks

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