Arsene I, Bearden I G, Beavis D, Besliu C, Budick B, Bøggild H, Chasman C, Christensen C H, Christiansen P, Cibor J, Debbe R, Enger E, Gaardhøje J J, Germinario M, Hagel K, Hansen O, Holm A, Ito H, Jipa A, Jundt F, Jørdre J I, Jørgensen C E, Karabowicz R, Kim E J, Kozik T, Larsen T M, Lee J H, Lee Y K, Lindal S, Lystad G, Løvhøiden G, Majka Z, Makeev A, McBreen B, Mikelsen M, Murray M, Natowitz J, Neumann B, Nielsen B S, Norris J, Ouerdane D, Płaneta R, Rami F, Ristea C, Ristea O, Röhrich D, Samset B H, Sandberg D, Sanders S J, Scheetz R A, Staszel P, Tveter T S, Videbaek F, Wada R, Yin Z, Zgura I S
Brookhaven National Laboratory, Upton, New York 11973, USA.
Phys Rev Lett. 2003 Aug 15;91(7):072305. doi: 10.1103/PhysRevLett.91.072305.
We present spectra of charged hadrons from Au+Au and d+Au collisions at sqrt[s(NN)]=200 GeV measured with the BRAHMS experiment at RHIC. The spectra for different collision centralities are compared to spectra from p+(-)p collisions at the same energy scaled by the number of binary collisions. The resulting ratios (nuclear modification factors) for central Au+Au collisions at eta=0 and eta=2.2 evidence a strong suppression in the high p(T) region (>2 GeV/c). In contrast, the d+Au nuclear modification factor (at eta=0) exhibits an enhancement of the high p(T) yields. These measurements indicate a high energy loss of the high p(T) particles in the medium created in the central Au+Au collisions. The lack of suppression in d+Au collisions makes it unlikely that initial state effects can explain the suppression in the central Au+Au collisions.
我们展示了在相对论重离子对撞机（RHIC）上利用BRAHMS实验测量的在√[s(NN)] = 200 GeV下金离子与金离子（Au+Au）以及氘核与金离子（d+Au）碰撞产生的带电强子的能谱。将不同碰撞中心度下的能谱与相同能量下质子与反质子（p+(-)p）碰撞的能谱进行比较，并按二元碰撞数进行缩放。在快度η = 0和η = 2.2处，中心金离子与金离子碰撞的结果比值（核修正因子）表明在高横动量（p(T)）区域（>2 GeV/c）有强烈的压低。相比之下，氘核与金离子的核修正因子（在η = 0处）显示出高p(T)产额的增强。这些测量结果表明在中心金离子与金离子碰撞产生的介质中，高p(T)粒子存在高能量损失。氘核与金离子碰撞中缺乏压低现象，这使得初始状态效应不太可能解释中心金离子与金离子碰撞中的压低现象。
