O. Dietzsch

Proton and pion production relative to the reaction plane in Au + Au collisions at 11A GeV/c

Results are presented of an analysis of proton and charged pion azimuthal distributions measured with respect to the reaction plane in Au + Au collisions at a beam momentum of about 11A GeV/c. The azimuthal anisotropy is studied as a function of particle rapidity and transverse momentum for different centralities of the collisions. The triple differential (in rapidity, transverse momentum, and azimuthal angle) distributions are reconstructed. A comparison of the results with a previous analysis of charged-particle and transverse energy flow as well as with model predictions are presented. {copyright} {ital 1997} {ital The American Physical Society}

Proton and pion production in Au+Au collisions at 10.8A GeV/c

We present proton and pion tranverse momentum spectra and rapidity distributions for Au+Au collisions at 10.8A GeV/c. The proton spectra exhibit collective transverse flow effects. Evidence of the influence of the Coulomb interaction from the fireball is found in the pion transverse momentum spectra. The data are compared with the predictions of the RQMD event generator.

Measurement of pion enhancement at low transverse momentum and of the Δ resonance abundance in Si-nucleus collisions at AGS energy

Abstract We present measurements of pion transverse momentum ( p t ) spectra in central Si-nucleus collisions in the rapidity range 2.0 y p t down to and including p t = 0. The data exhibit an enhanced pion yield at low p t compared to what is expected for a purely thermal spectral shape. This enhancement is used to determine the Δ resonance abundance at freeze-out. The results are consistent with a direct measurement of the Δ resonance yield by reconstruction of proton-pion pairs and imply a temperature of the system at freeze-out close to 140 MeV.We present measurements of the pion transverse momentum (p_t) spectra in central Si-nucleus collisions in the rapidity range 2.0<y<5.0 for p_t down to and including p_t=0. The data exhibit an enhanced pion yield at low p_t compared to what is expected for a purely thermal spectral shape. This enhancement is used to determine the Delta-resonance abundance at freeze-out. The results are consistent with a direct measurement of the Delta-resonance yield by reconstruction of proton-pion pairs and imply a temperature of the system at freeze-out close to 140 MeV.

Deuteron-induced reactions on 16O

Abstract Absolute differential cross sections were measured for the reactions 16 O(d, d) 16 O, 16 O(d, p) 17 O (ground state), 16 O(d, p) 17 O ∗ (0.87 MeV), 16 O(d, n) 17 F (ground state), 16 O(d,n) 17 F ast; (0.50 MeV) and 16 O(d, α) 14 N (ground state) from 2 to 3.5 MeV. Excitation functions were obtained at several angles, and angular distributions were measured at sufficiently small energy intervals to determine the structure in the cross sections. These data are analysed using the optical model, the Hauser-Feshbach theory and the distorted wave Born approximation. The fluctuations of the (d, d) and (d, p) cross sections with incident deuteron energy are analysed to give the compound nucleus and direct interaction contributions to these reactions.

Evidence for expansion of a hot fireball from two-pion correlations for Si + Pb collisions at AGS energy

Abstract The two-pion correlation function has been measured for charged pions produced in central 14.6 A GeV/ c Si + Pb collisions at the AGS. Data for like-sign pions show a clear quantum interference effect as expected for identical bosons. The experimental correlation function agrees well with that obtained for events generated by a cascade code (RQMD). The present data are consistent with a time-averaged rms freeze-out radius of 8.3 fm and a mean duration of pion emission of 9 fm/ c . The system has expanded considerably before freeze-out.

The ICEBall: a multiple element array for in-beam internal conversion electron spectroscopy

Abstract The construction and testing of a multiple-element mini-orange spectrometer array, the Pitt ICEBall, is described. The performance of the array in tests with sources and in in-beam studies is discussed, and the questions of gamma-ray, delta-ray and secondary electron background are addressed. The ICEBall has a maximum efficiency of 18% of 4π, in a compact package capable of inclusion within large gamma-detector arrays such as the Oak Ridge Spin Spectrometer.

Directed flow of light nuclei in Au + Au collisions at 10.8A GeV/c

Directed flow of deuterons, tritons,

Two-proton correlations from 14.6A GeV/c Si+Pb and 11.5A GeV/c Au+Au central collisions

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Particle spectra and correlations from experiment 814

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Two-particle correlations in Au+Au collisions at AGS energy

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