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1.
BEDANGADAS MOHANTY 《Pramana》2014,82(5):893-905
The transverse momentum spectra of the produced hadrons have been compared to a model, which is based on the assumption that a nucleus–nucleus collision is a superposition of isotropically decaying thermal sources at a given freeze-out temperature. The freeze-out temperature in nucleus–nucleus collisions is fixed from the inverse slope of the transverse momentum spectra of hadrons in nucleon–nucleon collision. The successive collisions in thessss nuclear reactions leads to gain in transverse momentum, as the nucleons propagate in the nucleus following a random walk pattern. The average transverse rapidity shift per collision is determined from the nucleon–nucleus collision data. Using this information, we obtain parameter-free result for the transverse momentum distribution of produced hadrons in nucleus–nucleus collisions. It is observed that such a model is able to explain the transverse mass spectra of the produced pions at SPS energies. However, it fails to satisfactorily explain the transverse mass spectra of kaons and protons. This indicates the presence of collective effect which cannot be accounted for, by the initial state collision broadening of transverse momentum of produced hadrons, the basis of random walk model. 相似文献
2.
Back BB Baker MD Ballintijn M Barton DS Betts RR Bickley AA Bindel R Busza W Carroll A Chai Z Decowski MP García E Gburek T George N Gulbrandsen K Halliwell C Hamblen J Hauer M Henderson C Hofman DJ Hollis RS Hołyński R Holzman B Iordanova A Johnson E Kane JL Khan N Kulinich P Kuo CM Lin WT Manly S Mignerey AC Nouicer R Olszewski A Pak R Reed C Roland C Roland G Sagerer J Seals H Sedykh I Smith CE Stankiewicz MA Steinberg P Stephans GS Sukhanov A Tonjes MB Trzupek A Vale C van Nieuwenhuizen GJ 《Physical review letters》2005,94(8):082304
We have measured transverse momentum distributions of charged hadrons produced in Au+Au collisions at sqrt[s(NN)]=62.4 GeV. The spectra are presented for transverse momenta 0.25
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3.
Transverse momentum and transverse mass distributions of charged hadrons produced in Au--Au collisions at high energies 下载免费PDF全文
The transverse momentum distribution and the transverse mass distribution of charged hadrons produced in nucleus nucleus collisions at high energies are described by using a two-cylinder model. The results calculated by the model are compared and found to be in agreement with the experimental data of the STAR and E895 Collaborations, measured in A~Au collisions at the relativistic heavy ion collider (RHIC) and alternating-gradient synchrotron (AGS) energies, respectively. In the energy range concerned, the excitation degree of emission source close to the central axis of cylinders increases obviously with the collision centrality and incident energy increasing, but it does not show any obvious change with the increase of the (pseudo)rapidity in central collisions. The excitation degree of emission source close to the side-surface of cylinders does not show any obvious change with the collision centrality, the (pseudo)rapidity, and the incident energy increasing. 相似文献
4.
Back BB Baker MD Ballintijn M Barton DS Becker B Betts RR Bickley AA Bindel R Budzanowski A Busza W Carroll A Decowski MP García E Gburek T George N Gulbrandsen K Gushue S Halliwell C Hamblen J Harrington AS Henderson C Hofman DJ Hollis RS Hołyński R Holzman B Iordanova A Johnson E Kane JL Khan N Kulinich P Kuo CM Lee JW Lin WT Manly S Mignerey AC Noell A Nouicer R Olszewski A Pak R Park IC Pernegger H Reed C Remsberg LP Roland C Roland G Sagerer J Sarin P Sawicki P Sedykh I Skulski W Smith CE 《Physical review letters》2003,91(7):072302
We have measured transverse momentum distributions of charged hadrons produced in d+Au collisions at sqrt[s(NN)]=200 GeV. The spectra were obtained for transverse momenta 0.25
相似文献
5.
Ján Pišút Neva Pišútová Petr Závada 《Zeitschrift fur Physik C Particles and Fields》1995,67(3):467-477
Density of matter produced in relativistic heavy-ion collisions depends substantially on the spacetime evolution of the collision and on the formation time of hadrons produced. Interactions of hadrons younger than their formation time are attenuated with respect to their normal values (transparency of hadronic matter for newly formed hadrons). The system of secondary hadrons produced in a heavy-ion collision thus expands as a gas of almost non interacting particles before hadrons reach their formation time. Densities of interacting hadronic matter produced in oxygen-lead and sulphur-lead collisions at 200 GeV/nucleon are estimated as a function of the formation time of hadrons. Uncertainties in our knowledge of the critical temepratureT c and of the formation time of hadrons τ0 permit at present three scenarios: an optimistic one (QGP has already been produced in collisions of oxygen and sulphur with heavy ions and will be copiously produced in Lead collisions), a pessimistic one (QGP cannot be produced at 200 GeV/nucleon) and an intermediate one (QGP has not been produced in oxygen and sulphur interactions with heavy ions and will be at best produced only marginally in Pb-collisions). We find the last opinion as most probable. 相似文献
6.
Adcox K Adler SS Ajitanand NN Akiba Y Alexander J Aphecetche L Arai Y Aronson SH Averbeck R Awes TC Barish KN Barnes PD Barrette J Bassalleck B Bathe S Baublis V Bazilevsky A Belikov S Bellaiche FG Belyaev ST Bennett MJ Berdnikov Y Botelho S Brooks ML Brown DS Bruner N Bucher D Buesching H Bumazhnov V Bunce G Burward-Hoy J Butsyk S Carey TA Chand P Chang J Chang WC Chavez LL Chernichenko S Chi CY Chiba J Chiu M Choudhury RK Christ T Chujo T Chung MS Chung P Cianciolo V Cole BA D'Enterria DG 《Physical review letters》2002,89(21):212301
Two-particle azimuthal correlation functions are presented for charged hadrons produced in Au+Au collisions at the Relativistic Heavy Ion Collider (sqrt [s(NN)]=130 GeV). The measurements permit determination of elliptic flow without event-by-event estimation of the reaction plane. The extracted elliptic flow values (v2) show significant sensitivity to both the collision centrality and the transverse momenta of emitted hadrons, suggesting rapid thermalization and relatively strong velocity fields. When scaled by the eccentricity of the collision zone epsilon, the scaled elliptic flow shows little or no dependence on centrality for charged hadrons with relatively low p(T). A breakdown of this epsilon scaling is observed for charged hadrons with pT >1.0 GeV/c. 相似文献
7.
Alver B Back BB Baker MD Ballintijn M Barton DS Betts RR Bindel R Busza W Chai Z Chetluru V García E Gburek T Gulbrandsen K Hamblen J Harnarine I Henderson C Hofman DJ Hollis RS Hołyński R Holzman B Iordanova A Kane JL Kulinich P Kuo CM Li W Lin WT Loizides C Manly S Mignerey AC Nouicer R Olszewski A Pak R Reed C Richardson E Roland C Roland G Sagerer J Sedykh I Smith CE Stankiewicz MA Steinberg P Stephans GS Sukhanov A Szostak A Tonjes MB Trzupek A van Nieuwenhuizen GJ Vaurynovich SS Verdier R 《Physical review letters》2006,96(21):212301
We present transverse momentum distributions of charged hadrons produced in Cu + Cu collisions at square root of SNN = 62.4 and 200 GeV. The spectra are measured for transverse momenta of 0.25 < pT < 5.0 GeV/c at square root of SNN = 62.4 GeV and 0.25 < pT < 7.0 GeV/c at square root of SNN = 200 GeV, in a pseudorapidity range of 0.2 < eta < 1.4. The nuclear modification factor R(AA) is calculated relative to p + p data at both collision energies as a function of collision centrality. At a given collision energy and fractional cross section, R(AA) is observed to be systematically larger in Cu + Cu collisions compared to Au + Au. However, for the same number of participating nucleons, R(AA) is essentially the same in both systems over the measured range of pT, in spite of the significantly different geometries of the Cu + Cu and Au + Au systems. 相似文献
8.
We present arguments supporting the conjecture that anomalous prompt photons observed recently in muon-proton interactions by the European Muon Collaboration (EMC) at CERN are of the same dynamical origin as low mass lepton pairs produced in hadronic collisions. The EMC data are found to be in a qualitative agreement with the soft annihilation model. The conjecture implies that the rate of anomalous photon production depends quadratically on the rapidity density of secondary hadrons in the rapidity region of the photon. A study of this dependence is suggested as a crucial test of the conjecture. 相似文献
9.
W. Bell A. Breakstone G. Claesson H. B. Crawley G. M. Dallavalle K. Doroba D. Drijard F. Fabbri A. Firestone M. A. Faessler H. G. Fischer S. Y. Fung S. Garpman W. Geist G. Giacomelli R. Gokieli M. Gorbics C. R. Gruhn P. Hanke M. Heiden W. Herr T. J. Ketel E. E. Kluge J. W. Lamsa T. Lohse I. Lund R. Mankel W. T. Meyer G. Mornacchi T. Nakada I. Otterlund M. Panter H. Pugh A. Putzer K. Rauschnabel B. Rensch F. Rimondi M. Schmelling L. Schroeder R. Sosnowski E. Stenlund T. J. M. Symons M. Szczekowski R. Szwed O. Ullaland R. Walczak D. Wegener M. Wunsch 《Zeitschrift für Physik A Hadrons and Nuclei》1986,325(1):7-14
Inelasticαα anddd collisions were studied at a centre-of-mass energy √S NN=31.2 GeV per nucleon-nucleon collision, using the Split-Field Magnet (SFM) detector at the CERN ISR. In this paper we show the inclusive and semi-inclusive rapidity distributions of protons, compare them with predictions of the Lund model, and calculate the average rapidity loss for participant protons. From the negative particles we calculate the inelasticity of the interaction, the average energy per particle, and the degree of isotropy of the produced hadrons. 相似文献
10.
T. Alber et al. 《The European Physical Journal C - Particles and Fields》1998,2(4):643-659
The transverse momentum and rapidity distributions of net protons and negatively charged hadrons have been measured for minimum
bias proton–nucleus and deuteron–gold interactions, as well as central oxygen–gold and sulphur–nucleus collisions at 200 GeV
per nucleon. The rapidity density of net protons at midrapidity in central nucleus–nucleus collisions increases both with
target mass for sulphur projectiles and with the projectile mass for a gold target. The
shape of the rapidity distributions of net protons forward of midrapidity for d+Au and central S+Au collisions is similar.
The average rapidity loss is larger than 2 units of rapidity for reactions with the gold target. The transverse momentum spectra
of net protons for all reactions can be described by a thermal distribution with ‘temperatures’ between MeV (p+S interactions) and MeV (central S+Au collisions). The multiplicity of negatively charged hadrons increases with the mass of the colliding system.
The shape of the transverse momentum spectra of negatively charged hadrons changes from minimum bias p+p and p+S interactions
to p+Au and central nucleus-nucleus collisions. The mean transverse momentum is almost constant in the vicinity of midrapidity
and shows little variation with the target and projectile masses. The average number of produced negatively charged hadrons
per participant baryon increases slightly from p+p, p+A to central S+S,Ag collisions.
Received: 28 October 1997 / Published online: 10 March 1998 相似文献
11.
F. Antinori et al. 《The European Physical Journal C - Particles and Fields》2000,14(4):633-641
The WA97 experiment has measured the transverse mass spectra for negative hadrons () and strange particles produced at mid–rapidity in Pb–Pb collisions. The increased statistics of analysed data samples allowed
us to perform a study of the spectra of , , , and as a function of the collision centrality. The data, which correspond to the most central 40% of the total inelastic cross
section, have been divided into four centrality classes according to the estimated number of nucleons taking part in the collision.
The spectra, analysed separately for each centrality bin, exhibit only weak ( 15%) centrality dependence. The deviation of the inverse slope from the linear dependence on the particle mass is confirmed even for the most central Pb–Pb collisions.
Received: 5 January 2000 / Revised version: 28 February 2000 / Published online: 14 April 2000 相似文献
12.
Back BB Baker MD Barton DS Betts RR Ballintijn M Bickley AA Bindel R Budzanowski A Busza W Carroll A Decowski MP García E George N Gulbrandsen K Gushue S Halliwell C Hamblen J Heintzelman GA Henderson C Hofman DJ Hollis RS Hołyński R Holzman B Iordanova A Johnson E Kane JL Katzy J Khan N Kucewicz W Kulinich P Kuo CM Lin WT Manly S McLeod D Michałowski J Mignerey AC Nouicer R Olszewski A Pak R Park IC Pernegger H Reed C Remsberg LP Reuter M Roland C Roland G Rosenberg L Sagerer J Sarin P 《Physical review letters》2003,91(5):052303
We present measurements of the pseudorapidity distribution of primary charged particles produced in Au+Au collisions at three energies, sqrt[s(NN)]=19.6, 130, and 200 GeV, for a range of collision centrali-ties. The distribution narrows for more central collisions and excess particles are produced at high pseudorapidity in peripheral collisions. For a given centrality, however, the distributions are found to scale with energy according to the "limiting fragmentation" hypothesis. The universal fragmentation region described by this scaling grows in pseudorapidity with increasing collision energy, extending well away from the beam rapidity and covering more than half of the pseudorapidity range over which particles are produced. This approach to a universal limiting curve appears to be a dominant feature of the pseudorapidity distribution and therefore of the total particle production in these collisions. 相似文献
13.
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》2006,96(22):222301
Deuteron-gold (d+Au) collisions at the Relativistic Heavy Ion Collider provide ideal platforms for testing QCD theories in dense nuclear matter at high energy. In particular, models suggesting strong saturation effects for partons carrying small nucleon momentum fraction (x) predict modifications to jet production at forward rapidity (deuteron-going direction) in d+Au collisions. We report on two-particle azimuthal angle correlations between charged hadrons at forward/backward (deuteron/gold going direction) rapidity and charged hadrons at midrapidity in d+Au and p+p collisions at square root of sNN=200 GeV. Jet structures observed in the correlations are quantified in terms of the conditional yield and angular width of away-side partners. The kinematic region studied here samples partons in the gold nucleus with x~0.1 to ~0.01. Within this range, we find no x dependence of the jet structure in d+Au collisions. 相似文献
14.
P. Lévai G. Papp G. G. Barnaföldi G. Fai 《The European physical journal. Special topics》2008,155(1):89-99
We present our results on neutral pion (π0) production
in pp and dAu collisions at RHIC energy. Pion spectra
are calculated in a next-to-leading
order (NLO) perturbative QCD-based model.
The model includes the transverse component of the
initial parton distribution (“intrinsic kT”).
We compare our results to the available experimental data from RHIC,
and fit the data with high precision.
The calculation tuned this way is repeated for the dAu collision,
and used to investigate the interplay of shadowing and
multiple scattering at RHIC.
The centrality dependence of the nuclear modification
factor shows a measurable difference between different
shadowing parameterizations. 相似文献
15.
Adler C Ahammed Z Allgower C Amonett J Anderson BD Anderson M Averichev GS Balewski J Barannikova O Barnby LS Baudot J Bekele S Belaga VV Bellwied R Berger J Bichsel H Billmeier A Bland LC Blyth CO Bonner BE Boucham A Brandin A Bravar A Cadman RV Caines H Calderón de la Barca Sánchez M Cardenas A Carroll J Castillo J Castro M Cebra D Chaloupka P Chattopadhyay S Chen Y Chernenko SP Cherney M Chikanian A Choi B Christie W Coffin JP Cormier TM Cramer JG Crawford HJ Deng WS Derevschikov AA 《Physical review letters》2002,89(20):202301
Inclusive transverse momentum distributions of charged hadrons within 0.2
相似文献
16.
We study the effect of spatially homogeneous and inhomogeneous shadowing on J/psi production in deuterium-nucleus collisions. We discuss how the shadowing and its spatial dependence can be measured by comparing central and peripheral dA collisions. These event classes may be selected by using gray protons from heavy ion breakup and events where the proton or neutron in the deuterium does not interact. We find that inhomogeneous shadowing has a significant effect on central dA collisions, larger than expected in central AA collisions. Results are presented for dAu collisions at sqrt[s(NN)]=200 GeV and dPb collisions at sqrt[s(NN)]=6.2 TeV. 相似文献
17.
M. Calderón de la Barca Sánchez 《The European Physical Journal C - Particles and Fields》2005,43(1-4):187-192
Charmed hadrons are interesting observables in heavy ion collisions. They are becoming more accessible to experimental scrutiny
at RHIC energies due to the increased production cross-section of charm with the larger centre-of-mass energy available at
RHIC compared to SPS. One source of interest in charm production is due to the fact that gluon fusion dominates the charm
production cross-section at high energy. Hence, a measurement of charm hadrons is directly sensitive to the gluon distributions
of the colliding particles. In addition, any measurement of production at RHIC, and more importantly any observed suppression,
must be compared to the overall production of pairs. A systematic study of charmed hadrons in all collision systems available
at RHIC is therefore an invaluable experimental tool in the characterization of the matter produced at RHIC. In particular,
d + Au collisions are a necessary step for the comparison of any possible modification of charm production in Au + Au collisions.
We present preliminary results on D meson production from d + Au collisions in STAR at = 200 .
Arrival of the final proofs: 26 July 2005
PACS:
13.20.Fc, 13.25.Ft, 25.75.-q, 24.85. + p 相似文献
18.
G. Wolschin 《Annalen der Physik》2008,17(7):462-476
The short parton production phase in high‐energy heavy‐ion collisions is treated analytically as a nonlinear diffusion process. The initial buildup of the rapidity density distributions of produced charged hadrons within τp? 0.25 fm/c occurs in three sources during the colored partonic phase. In a two‐step approach, the subsequent diffusion in pseudorapidity space during the interaction time of τint? 7‐10 fm/c (mean duration of the collision) is essentially linear as expressed in the Relativistic Diffusion Model (RDM) which yields excellent agreement with the data at RHIC energies, and allows for predictions at LHC energies. Results for d+Au are discussed in detail. 相似文献
19.
运用修正的超相对论量子分子动力学模型研究了交变梯度同步加速器(AGS)能区Au+Au碰撞中的核阻止效应. 该模型考虑了形成和"预形成"粒子的平均场势、核子-核子弹性散射反应截面的介质修正和碎块形成的判断条件. 研究发现: 在AGS能区, 核阻止效应受到形成和“预形成”粒子的平均场势和核子-核子弹性散射反应截面介质修正的影响; 在中心快度区自由质子的产额偏大, 考虑新的碎块形成判断条件后, 此模型的理论计算结果与自由质子的实验结果符合得很好.
关键词:
超相对论量子分子动力学模型
交变梯度同步加速器能区
Au+Au碰撞
核阻止效应 相似文献
20.
C. Spieles L. Gerland N. Hammon M. Bleicher S.A. Bass H. Stöcker W. Greiner C. Lourenço R. Vogt 《The European Physical Journal C - Particles and Fields》1998,5(2):349-355
A study of secondary Drell-Yan production in nuclear collisions is presented for SPS energies. In addition to the lepton
pairs produced in the initial collisions of the projectile and target nucleons, we consider the potentially high dilepton
yield from hard valence antiquarks in produced mesons and antibaryons. We calculate the secondary Drell-Yan contributions
taking the collision spectrum of hadrons from the microscopic model URQMD. The contributions from meson-baryon interactions,
small in hadron-nucleus interactions, are found to be substantial in nucleus-nucleus collisions at low dilepton masses. Preresonance
collisions of partons may further increase the yields.
Received: 9 July 1997 / Revised version: 17 December 1997 / Published online: 10 March 1998 相似文献