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Identified hadron transverse momentum spectra in Au+Au collisions at s NN = 62.4 GeV

2007; American Institute of Physics; Volume: 75; Issue: 2 Linguagem: Inglês

10.1103/physrevc.75.024910

1538-4497

B. B. Back, M. D. Baker, M. Ballintijn, D. S. Barton, Russell Richard Betts, A. A. Bickley, R. Bindel, W. Busza, A. Carroll, Z. Chai, M. P. Decowski, E. Garcı́a, T. Gburek, N. George, K. Gulbrandsen, C. Halliwell, J. Hamblen, M. Hauer, C. Henderson, D. J. Hofman, R. S. Hollis, R. Hołyński, B. Holzman, A. Iordanova, E. Johnson, J. L. Kane, N. Khan, P. Kulinich, C. M. Kuo, W.T. Lin, S. Manly, A. C. Mignerey, R. Nouicer, A. Olszewski, R. Pak, C. Reed, C. Roland, G. Roland, J. Sagerer, H. Seals, I. Sedykh, Christopher Smith, M. A. Stankiewicz, P. Steinberg, G. S. F. Stephans, A. Sukhanov, M. B. Tonjes, A. Trzupek, C. Vale, G. J. van Nieuwenhuizen, S. S. Vaurynovich, R. Verdier, G. I. Veres, E. A. Wenger, F. L. H. Wolfs, B. K. Wosiek, K. W. Woźniak, B. Wysłouch,

Particle physics theoretical and experimental studies

Transverse momentum spectra of pions, kaons, protons, and antiprotons from Au+Au collisions at $\sqrt{{s}_{\mathit{NN}}}$ = 62.4 GeV have been measured by the PHOBOS experiment at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory. The identification of particles relies on three different methods: low momentum particles stopping in the first detector layers; the specific energy loss ($\mathit{dE}/\mathit{dx}$) in the silicon spectrometer, and time-of-flight measurement. These methods cover the transverse momentum ranges 0.03--0.2, 0.2--1.0, and 0.5--3.0 GeV/$c$, respectively. Baryons are found to have substantially harder transverse momentum spectra than mesons. The ${p}_{T}$ region in which the proton to pion ratio reaches unity in central Au+Au collisions at $\sqrt{{s}_{\mathit{NN}}}$ = 62.4 GeV fits into a smooth trend as a function of collision energy. At low transverse mass, the spectra of various species exhibit a significant deviation from transverse mass scaling. The observed particle yields at very low ${p}_{T}$ are comparable to extrapolations from higher ${p}_{T}$ for kaons, protons and antiprotons. By comparing our results to Au+Au collisions at $\sqrt{{s}_{\mathit{NN}}}$ = 200 GeV, we conclude that the net proton yield at midrapidity is proportional to the number of participant nucleons in the collision.