Centrality and energy dependence of charged-particle multiplicities in heavy ion collisions in the context of elementary reactions
- Argonne National Laboratory, Argonne, Illinois 60439-4843 (United States)
- Brookhaven National Laboratory, Upton, New York 11973-5000 (United States)
- University of Illinois at Chicago, Chicago, Illinois 60607-7059 (United States)
The PHOBOS experiment at the BNL Relativistic Heavy Ion Collider has measured the total multiplicity of primary charged particles as a function of collision centrality in Au+Au collisions at {radical}(s{sub NN})= 19.6, 130, and 200 GeV. An approximate independence of <N{sub ch}>/<N{sub part}/2> on the number of participating nucleons is observed, reminiscent of 'wounded nucleon' scaling (N{sub ch}{proportional_to}N{sub part}) observed in proton-nucleus collisions. Unlike p+A, the constant of proportionality does not seem to be set by the pp/pp data at the same energy. Rather, there seems to be a surprising correspondence with the total multiplicity measured in e{sup +}e{sup -} annihilations, as well as the rapidity shape measured over a large range. The energy dependence of the integrated multiplicity per participant pair shows that e{sup +}e{sup -} and A+A data agree over a large range of center-of-mass energies ({radical}(s)>20 GeV), and pp/pp data can be brought to agree approximately with the e{sup +}e{sup -} data by correcting for the typical energy taken away by leading particles. This is suggestive of a mechanism for soft particle production that depends mainly on the amount of available energy. It is conjectured that the dominant distinction between A+A and p+p collisions is the multiple collisions per participant, which appears to be sufficient to substantially reduce the energy taken away by leading particles.
- OSTI ID:
- 20863694
- Journal Information:
- Physical Review. C, Nuclear Physics, Vol. 74, Issue 2; Other Information: DOI: 10.1103/PhysRevC.74.021902; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2813
- Country of Publication:
- United States
- Language:
- English
Similar Records
UNIVERSAL BEHAVIOR OF CHARGED PARTICLE PRODUCTION IN HEAVY ION COLLISIONS AT RHIC ENERGIES.
UNIVERSAL BEHAVIOR OF CHARGED PARTICLE PRODUCTION IN HEAVY ION COLLISIONS AT RHIC ENERGIES.