AbstractThe PHOBOS experiment at the Relativistic Heavy Ion Collider (RHIC), comprising the spectrometer with multiple layers of silicon wafers, is an excellent detector for very low transverse ...momentum (pT) particles. Transverse momentum distributions of π–+π+, K–+K+ and \(p+\overline{p}\) produced at mid-rapidity are presented for the 15% most central Au-Au collisions at \(\sqrt{s_{NN}}\) = 200 GeV. The momentum ranges for measured particles are from 30 to 50 MeV/c for pions, 90 to 130 MeV/c for kaons and 140 to 210 MeV/c for protons and antiprotons. The measurement method is briefly described. A comparison of the pT spectra to experimental results at higher particle momenta and to model predictions is discussed. PACS: 25.75.-q
We present transverse momentum distributions of charged hadrons produced in Au+Au collisions at sNN=200 GeV. The spectra were measured for transverse momenta pT from 0.25 to 4.5 GeV/c in a ...pseudorapidity range of 0.2<η<1.4. The evolution of the spectra is studied as a function of collision centrality, from 65 to 344 participating nucleons. The results are compared to data from proton–antiproton collisions and Au+Au collisions at lower RHIC energies. We find a significant change of the spectral shape between proton–antiproton and semi-peripheral Au+Au collisions. Comparing semi-peripheral to central Au+Au collisions, we find that the yields at high pT exhibit approximate scaling with the number of participating nucleons, rather than scaling with the number of binary collisions.
PHOBOS is one of the four experiments at the Relativistic Heavy Ion Collider measuring
p + p, d + Au, and
Au + Au collisions over a broad range of energies. PHOBOS is a silicon-pad based detector ...with a 4π multiplicity detector and a high resolution mid-rapidity spectrometer, along with other detectors (time-of-flight walls, proton and zero degree calorimeters). PHOBOS is able to measure particles at low transverse momentum, spectra, flow, particle ratios, and multiplicity over a large region of phase space. A comparison of results for
Au + Au and
d + Au collisions at
√S
NN = 220GeV
will be discussed.
The PHOBOS experiment at RHIC has recorded measurements for AuAu collisions spanning nucleon-nucleon center-of-mass energies from √
S
NN
= 19.6 GeV to 200 GeV. Global observables such as elliptic ...flow and charged particle multiplicity provide important constraints on model predictions that characterize the state of matter produced in these collisions. The nearly 4π acceptance of the PHOBOS experiment provides excellent coverage for complete flow and multiplicity measurements. Results including beam energy and centrality dependencies are presented and compared to elementary systems.
Excitation functions were measured for complex fragments with atomic number Z = 5–25 emitted from the compound nuclei
90,94,98Mo produced in the reactions
78,82,86Kr +
12C
. Mass-asymmetric fission ...barriers were extracted by fitting the excitation functions with a transition state formalism. The extracted barriers are several MeV higher on average than the calculations of the Rotating Finite-Range Model and substantially lower than predicted by the Rotating Liquid Drop Model. The symmetric fission barriers measured support the hypothesis of a congruence term that doubles for the fission of strongly indented saddle-point shapes. The excitation functions were analyzed to search for atomic number
Z- and energy
E-dependent deviations from transition-state-method predictions. All of the measured excitation functions can be scaled onto a single universal straight line according to the transition-state predictions. No
Z- and/or
E-dependent effects that could be attributed to transient effects are visible.
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