共查询到20条相似文献,搜索用时 15 毫秒
1.
Tadaaki Isobe 《Acta Physica Hungarica A》2006,27(2-3):227-230
Neutral pions (π0) in √NN=200 GeV and 62.4 GeV Au+Au collisions were measured at RHIC-PHENIX Year-4 Run. In √NN=200 GeV, π0 spectra are measured up to p T=20 GeV/c. A strong suppression by a factor of ~5 is observed and stays almost constant up to 20 GeV/c. 相似文献
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Kentaro Miki 《中国物理 C》2007,31(12)
Azimuthal anisotropy of direct photon is measured in (√SNN)=200GeV Au Au collisions at RHICPHENIX. Direct photon is one of the most effective probes to study properties of hot dence medium at initial state (also QGP state) of heavy ion collisions because photons almost do not interact strongly with any other particles caused by its long mean free path and they keep their conditions when they are created. Within statistical and systematic errors, the elliptic flow parameter (v2) of direct photon is consistent with zero.Direct photon v2 is estimated by hadron decay photon contamination are subtracted from inclusive photon v2 in intermediate to high transverse momentum (pT) region (0 to 10GeV/c) for 3 centrality selections (20% steps) and minimum bias. 相似文献
4.
Alber T Bächler J Bartke J Bialkowska H Bloomer MA Bock R Braithwaite WJ Brinkmann D Brockmann R Buncic P Chan P Cramer PB Cramer JG Derado I Eckardt V Eschke J Favuzzi C Ferenc D Fleischmann B Foka P Freund P Fuchs M Gazdzicki M Gladysz E Harris JW Hoffman M Jacobs P Kabana S Kadija K Kosiec J Kowalski M Kühmichel A Lahanas M Lee JY Ljubicic A Margetis S Mitchell JT Morse RJ Nappi E Odyniec G Paic G Panagiotou AD Petridis A Piper A Posa F Poskanzer AM Pühlhofer F Rauch W Renfordt R Retyk W 《Physical review letters》1995,74(8):1303-1306
5.
We investigate the squeezed back-to-back correlations(BBC) of K~+K~-, caused by the mass modification of particles in the dense medium formed in d + Au collisions at sNN~(1/2)= 200 GeV and Au + Au collisions at sNN~(1/2)= 62.4 GeV. Considering that some kaons may not be affected by the medium, we further study the BBC functions of K~+K~-when parts of all kaons have a mass-shift. Our results indicate that the BBC functions of K~+K~-can be observed when only ~10% of all kaons have a mass-shift in d + Au collisions at sNN~(1/2) = 200 GeV and the peripheral collisions of Au + Au at sNN~(1/2)= 62.4 GeV. Since the BBC function is caused by the mass-shift due to the interactions between the particle and the medium, the successful detection of the BBC function indirectly marks that the dense medium has formed in these collision systems. We suggest the experimental measurement of the BBC function of K~+K~- in d + Au collisions at sNN~(1/2) = 200 GeV and peripheral collisions of Au + Au at sNN~(1/2) = 62.4 GeV. 相似文献
6.
Betty I. Bezverkhny 《Acta Physica Hungarica A》2006,27(2-3):205-208
Angular correlations between produced high-p TΞ? baryons and unidentified charged and neutral particles are observed in high-tower triggered (on a large electromagnetic energy deposit) √s=200 GeV p+p collisions. This trigger favors events with higher average multiplicity than those in minimum bias. These events are likely to contain jets. The average multiplicity of a high-tower triggered event is similar to that of a minimum bias event containing a Ξ baryon, which implies that Ξ baryons are likely to be produced in jets. Ξ? <p T> is higher in the triggered data then in the minimum bias sample. 相似文献
7.
Adler SS Afanasiev S Aidala C Ajitanand NN Akiba Y Alexander J Amirikas R Aphecetche L Aronson SH Averbeck R Awes TC Azmoun R Babintsev V Baldisseri A Barish KN Barnes PD Bassalleck B Bathe S Batsouli S Baublis V Bazilevsky A Belikov S Berdnikov Y Bhagavatula S Boissevain JG Borel H Borenstein S Brooks ML Brown DS Bruner N Bucher D Buesching H Bumazhnov V Bunce G Burward-Hoy JM Butsyk S Camard X Chai JS Chand P Chang WC Chernichenko S Chi CY Chiba J Chiu M Choi IJ Choi J Choudhury RK Chujo T 《Physical review letters》2004,93(15):152302
Bose-Einstein correlations of identically charged pion pairs were measured by the PHENIX experiment at midrapidity in Au + Au collisions at square root s(NN)=200 GeV. The Bertsch-Pratt radius parameters were determined as a function of the transverse momentum of the pair and as a function of the centrality of the collision. Using the standard core-halo partial Coulomb fits, and a new parametrization which constrains the Coulomb fraction as determined from the unlike-sign pion correlation, the ratio R(out)/R(side) is within 0.8-1.1 for 0.25< <1.2 GeV/c. The centrality dependence of all radii is well described by a linear scaling in N(1/3)(part), and R(out)/R(side) for approximately 0.45 GeV/c is approximately constant at unity as a function of centrality. 相似文献
8.
J. B?chler J. Bartke H. Bia?kowska R. Bock R. Brockmann P. Buncic S. I. Chase I. Derado V. Eckardt J. Eschke et al. 《Zeitschrift fur Physik C Particles and Fields》1992,56(3):347-354
Multiplicity distributions and their second moments fornegatively charged particles produced in32S-S central and minimum bias interactions at 200A GeV are studied in various rapidity intervals. Fritiof and Venus models mostly describe the dependence of second moments on rapidity intervals in minimum bias interactions, but not in central collisions. For central collisions the behaviour of second moments might indicate enhanced multiplicity fluctuations. 相似文献
9.
Bearden IG Bøggild H Boissevain J Christiansen PH Conin L Dodd J Erazmus B Esumi S Fabjan CW Ferenc D Franz A Gaardhøje JJ Hansen AG Hansen O Hardtke D van Hecke H Holzer EB Humanic TJ Hummel P Jacak BV Kaimi K Kaneta M Kohama T Kopytine M Leltchouk M Ljubicic A Lörstad B Maeda N Martin L Medvedev A Murray M Ohnishi H Paic G Pandey SU Piuz F Pluta J Polychronakos V Potekhin M Poulard G Reichhold D Sakaguchi A Schmidt-Sørensen J Simon-Gillo J Sondheim W Sugitate T Sullivan JP Sumi Y Willis WJ 《Physical review letters》2001,87(11):112301
Two-particle interferometry of positive kaons is studied in Pb+Pb collisions at mean transverse momenta
approximately 0.25 and 0.91 GeV/c. A three-dimensional analysis was applied to the lower p(T) data, while a two-dimensional analysis was used for the higher p(T) data. We find that the source-size parameters are consistent with the m(T) scaling curve observed in pion-correlation measurements in the same collisions, and that the duration time of kaon emission is consistent with zero within the experimental sensitivity. 相似文献
10.
J. Schukraft 《Zeitschrift fur Physik C Particles and Fields》1988,38(1):59-64
Multiplicity distributions of charged particles have been measured in the pseudorapidity region 0.9 <η lab < 4.9 for oxygen-tungsten collisions at an incident energy of 200 GeV per nucleon. The multiplicity cross-sectiondσ/dN as measured in the backward hemisphere (0.9 <η lab < 2.9) is found to be very similar in shape to the transverse energy distributiondσ/dE T published previously by this group, reflecting the particular geometry of nucleus-nucleus collisions. Pseudorapidity distributionsdN/dη are presented and their dependence onE T is discussed. The average transverse energy per charged particle is studied versusE T and is found to be constant within our systematic error of approximately 10%. 相似文献
11.
T. C. Awes C. Barlag F. Berger M. A. Bloomer C. Blume D. Bock R. Bock E. -M. Bohne D. Bucher A. Claussen G. Clewing L. Dragon A. Eklund S. Garpman R. Glasow H. Gustafsson H. H. Gutbrod G. Hölker J. Idh P. Jacobs K. H. Kampert B. W. Kolb H. Löhner I. Lund F. E. Obenshain A. Oskarsson I. Otterlund T. Peitzmann F. Plasil A. M. Poskanzer M. Purschke B. Roters S. Saini R. Santo H. R. Schmidt S. P. Sørensen K. Steffens P. Steinhaeuser E. Stenlund D. Stüken G. R. Young 《Zeitschrift fur Physik C Particles and Fields》1995,65(2):207-213
Correlations between protons are studied in the target fragmentation region of reactions of protons and16O with C, Cu, Ag, Au and of32S with Al and Au at 200A GeV. The emitted protons were measured with the Plastic Ball detector in the WA80 experiment at the CERN SPS. The comparison of the correlation function with calculations, assuming a spherical, gaussian shaped source with a lifetime τ=0 fm/c, allows the extraction of radius parameters. The values are very close to those expected from the geometry of the target nuclei and increase with the target mass as αA Target 1/3 . Even in proton induced reactions the whole target nucleus is involved. The dependence of the radii on centrality, polar angleθ lab, and energy, and their relation to measured proton yields are presented. 相似文献
12.
《Physics letters. [Part B]》1988,207(1):6-10
Assuming complete inelasticity of nuclear collisions at 200 GeV/A we consider the properties of the arising high temperature and density nuclear matter fireball. Pion multiplicity and particle rapidity distribution can be estimated and correlated with other properties of the fireball. Consistency of the fireball reaction picture with the quark-gluon plasma structure is shown. 相似文献
13.
R. Baur A. Breskin R. Chechik A. Drees C. Jacob U. Faschingbauer P. Fischer Z. Fraenkel E. Gatti P. Glässel Th. Günzel C. P. de los Heros F. Hess D. Irmscher B. Lenkeit L. H. Olsen Y. Panebrattsev A. Pfeiffer I. Ravinovich P. Rehak A. Schön J. Schukraft M. Sampietro A. Shor H. J. Specht V. Steiner S. Tapprogge G. Tel-Zur I. Tserruya Th. Ullrich J. P. Wurm 《Zeitschrift fur Physik C Particles and Fields》1996,71(1):571-577
The CERES experiment has measured inclusive photon production in S-Au collisions of 200 GeV/nucleon at the CERN SPS. No evidence for direct emission of photons was found. For the kinematic region 2.1<y<2.65 and 0.4 GeV/c<p⊥<2.0 GeV/c the yield andp⊥-dependence of the observed photons are well reproduced by hadron decays. Furthermore, their production rate is found to be proportional to the charged particle density. The systematic errors comparing the measured and expected photon yield result in an upper limit of 14% for the emission of direct photons in central S-Au collisions. For a photon source with a yield depending quadratically on the charged particle density the limit can be reduced to 7%. 相似文献
14.
R. Baur A. Breskin R. Chechik A. Drees C. Jacob U. Faschingbauer P. Fischer Z. Fraenkel E. Gatti P. Gl?ssel Th. G��nzel C. P. de los Heros F. Hess D. Irmscher B. Lenkeit L. H. Olsen Y. Panebrattsev A. Pfeiffer I. Ravinovich P. Rehak A. Sch?n J. Schukraft M. Sampietro A. Shor H. J. Specht V. Steiner S. Tapprogge G. Tel-Zur I. Tserruya Th. Ullrich J. P. Wurm 《The European Physical Journal C - Particles and Fields》2011,71(1):571-577
The CERES experiment has measured inclusive photon production in S-Au collisions of 200 GeV/nucleon at the CERN SPS. No evidence for direct emission of photons was found. For the kinematic region 2.1<y<2.65 and 0.4 GeV/c<p??<2.0 GeV/c the yield andp??-dependence of the observed photons are well reproduced by hadron decays. Furthermore, their production rate is found to be proportional to the charged particle density. The systematic errors comparing the measured and expected photon yield result in an upper limit of 14% for the emission of direct photons in central S-Au collisions. For a photon source with a yield depending quadratically on the charged particle density the limit can be reduced to 7%. 相似文献
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16.
M. Neubert 《Zeitschrift fur Physik C Particles and Fields》1989,42(2):231-242
A calculation of sources of inclusive photons in ultrarelativistic O-W and Pb-Pb collisions at 200 GeV/u is presented. The production of thermal photons in a quark-gluon plasma, a deconfined state of nuclear matter at high energy density, is addressed. In events with a large amount of energy deposited in the target the thermal contribution to the inclusive spectrum is found to be ~5%, quadratically increasing with particle multiplicity, but only weakly dependent on the size of the projectile nucleus. These photons are predominantly produced in a coexistence phase of plasma and hadronic matter. Hadronic bremsstrahlung is investigated including the spatial and temporal coherence due to the large space-time extension of heavy-ion systems. For small photon momenta there is a coherent signal in the fragmentation regions proportional to the squared number of participant protons. 相似文献
17.
R. Albrecht T. C. Awes P. Beckmann F. Berger M. A. Bloomer D. Bock R. Bock G. Claesson G. Clewing L. Dragon A. Eklund R. L. Ferguson A. Franz S. Garpman R. Glasow H. Å. Gustafsson H. H. Gutbrod M. Hartig G. Hölker J. Idh P. Jacobs K. H. Kampert B. W. Kolb P. Kristiansson H. Löhner I. Lund F. E. Obenshain A. Oskarsson I. Otterlund T. Peitzmann S. Persson F. Plasil A. M. Poskanzer M. Purschke H. G. Ritter B. Roters S. Saini R. Santo H. R. Schmidt R. Schmidt S. P. Sørensen K. Steffens P. Steinhauser E. Stenlund D. Stüken M. L. Tincknell A. Twyhues G. R. Young 《Zeitschrift fur Physik C Particles and Fields》1992,53(2):225-237
Correlations between positive pions are investigated in the target fragmentation region of 200A GeV16O+nucleus collisions. The pions are measured with the Plastic Ball detector in the WA80 experiment at the CERN SPS. The target mass dependence of the radii and the correlation strength extracted by interferometry is studied. A new approach to the fit of the correlation function is introduced. The correlation strength and both invariant and transverse radii increase with decreasing target mass. The transverse radius for16O+C reactions appears to be much larger than the geometrical radius of the nuclei involved. For the Au target only a small fraction of the measured pions contributes to the apparent correlation. Hints for a much larger second component in16O+Au reactions are observed. Rescattering phenomena may provide a clue to understand these phenomena. 相似文献
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Adler SS Afanasiev S Aidala C Ajitanand NN Akiba Y Al-Jamel A Alexander J Aoki K Aphecetche L Armendariz R Aronson SH Averbeck R Awes TC Babintsev V Baldisseri A Barish KN Barnes PD Bassalleck B Bathe S Batsouli S Baublis V Bauer F Bazilevsky A Belikov S Bjorndal MT Boissevain JG Borel H Brooks ML Brown DS Bruner N Bucher D Buesching H Bumazhnov V Bunce G Burward-Hoy JM Butsyk S Camard X Chand P Chang WC Chernichenko S Chi CY Chiba J Chiu M Choi IJ Choudhury RK Chujo T Cianciolo V Cobigo Y 《Physical review letters》2007,98(1):012002
Cross sections for midrapidity production of direct photons in p+p collisions at the Relativistic Heavy Ion Collider (RHIC) are reported for transverse momenta of 3 < pT < 16 GeV/c. Next-to-leading order perturbative QCD (pQCD) describes the data well for pT >5 GeV/c, where the uncertainties of the measurement and theory are comparable. We also report on the effect of requiring the photons to be isolated from parton jet energy. The observed fraction of isolated photons is well described by pQCD for pT >7 GeV/c. 相似文献
20.
Adare A Afanasiev S Aidala C Ajitanand NN Akiba Y Al-Bataineh H Alexander J Aoki K Aphecetche L Armendariz R Aronson SH Asai J Atomssa ET Averbeck R Awes TC Azmoun B Babintsev V Baksay G Baksay L Baldisseri A Barish KN Barnes PD Bassalleck B Bathe S Batsouli S Baublis V Bazilevsky A Belikov S Bennett R Berdnikov Y Bickley AA Boissevain JG Borel H Boyle K Brooks ML Buesching H Bumazhnov V Bunce G Butsyk S Campbell S Chang BS Charvet JL Chernichenko S Chiba J Chi CY Chiu M Choi IJ Chujo T Chung P 《Physical review letters》2006,97(25):252002
The momentum distribution of electrons from decays of heavy flavor (charm and bottom) for midrapidity absolute value of y < 0.35 in p + p collisions at square root of s = 200 GeV has been measured by the PHENIX experiment at the BNL Relativistic Heavy Ion Collider over the transverse momentum range 0.3 < pT < 9 GeV/c. Two independent methods have been used to determine the heavy-flavor yields, and the results are in good agreement with each other. A fixed-order-plus-next-to-leading-log perturbative QCD calculation agrees with the data within the theoretical and experimental uncertainties, with the data/theory ratio of 1.71+/-0.02stat+/-0.18sys for 0.3 < pT < 9 GeV/c. The total charm production cross section at this energy has also been deduced to be sigma cc = 567+/-57stat+/-193sys microb. 相似文献