O. Hansen

HADRON-PRODUCTION IN NUCLEON NUCLEON COLLISIONS AT 200 GEV/C - A COMPILATION

Abstract Data on stable hadron production in p + p and p + n interactions at 200 GeV/ c are reviewed. Methods to construct missing data in the p + p, p + n, and n + n interactions are derived from charge symmetry and charge, baryon and strangeness conservation, and used to yield nucleon-nucleon interaction results. These may be useful for evaluating nucleus-nucleus collision measurements in terms of enhancements and suppressions. Parameterizations of p t 2 and rapidity distributions are presented to provide yields in acceptance cuts for comparisons to nucleus-nucleus data. As an example the derived nucleon-nucleon multiplicities are reduced to the acceptances of the NA-35 CERN S + S experiment.

A Single arm spectrometer detector system for high-energy heavy ion experiments

The recent availability of 14.6 GeV/c per nucleon 16O and 28Si ions from the Brookhaven National Laboratory Tandem-AGS accelerator facility has prompted the design, construction and operation of a large-solid-angle (25 msr) magnetic spectrometer with particle identification from ∼0.5 to ∼4.7 GeV/c. A small-solid-angle Cherenkov counter complex views the target through the magnet and extends the particle identification up to ∼15 GeV/c. This experiment (E-802) employs event characterization detectors, a charged-particle multiplicity array, a highly segmented lead-glass detector, and a zero degree calorimeter. The facility measures momentum spectra of identified heavy-ion-produced hadrons with high resolution (Δp/p≤0.005) as a function of collision centrality given by triggers from the event characterization detectors. Construction and performance details of the spectrometer components and auxiliary detectors are described.

Resonances in elastic and inelastic scattering of 24Mg+24Mg

Abstract Excitation functions for elastic and inelastic scattering of 24 Mg+ 24 Mg have been measured in 100 keV steps over the bombarding energy range 84–100 MeV. Strong narrow resonances are observed correlated in many channels. The data are compared with similar results for the 28 Si+ 28 Si system.

Centrality dependence of kaon yields in Si + A and Au + Au collisions at the AGS

Charged kaon production has been measured in Si+Al and Si+Au collisions at 14.6 A GeV/c, and Au+Au collisions at 11.1 A GeV/c by Experiments 859 and 866 (the E--802 Collaboration) at the BNL AGS. Invariant transverse mass spectra and rapidity distributions for both K+ and K- are presented. The centrality dependence of rapidity-integrated kaon yields is studied. Strangeness enhancement is observed as an increase in the slope of the kaon yield with the total number of participants as well as the yield per participant. The enhancement starts with peripheral Si+Al and Si+Au collisions (relative to N+N) and appears to saturate for a moderate number of participating nucleons in Si+Au collisions. It is also observed to increase slowly with centrality in Au+Au collisions, to a level in the most central Au+Au collisions that is greater than that found in central Si+A collisions. The enhancement factor for

Measurement of energy emission from O+A and p+A collisions at 14.5 GeV/c per nucleon with a lead-glass array

K^+

Onset of diffraction-like angular distributions in the 40Ca(13C, 12C)41Ca reaction

production are 3.0 +-0.2(stat.) +-0.4(syst.) and 4.0 +-0.3(stat.) +-0.5(syst.), respectively, for the most central 7% Si+Au collisions and the most central 4% Au+Au collisions relative to N+N at the correponding beam energy.

Production of η mesons in 200 AGeV/cS+S and S+Au reactions

Abstract The first data from a 16O beam of total energy 232 GeV at the BNL Tandem-AGS are reported. A lead-glass array covering the laboratory pseudo-rapidity interval 1.25

One- and two-neutron transfer reactions with 14C

Abstract The angular distribution of the 40 Ca( 13 C, 12 C) 41 Ca(g.s.) reaction has been measured at incident energies of 60 and 68 MeV. Oscillations in the differential cross section were observed at these energies but not at previously measured, lower energies of 40 and 48 MeV. Arguments are presented which indicate that diffraction-like angular distributions are a systematic feature of heavy-ion reactions.

Results from the BNL E802 spectrometer for 14.5 GeV/c per nucleon silicon beams

Abstract Minimum Bias production cross sections of η mesons have been measured in 200 AGeV/cS+Au and S+S collisions at the CERN SPS by reconstructing the η → γγ decay. The measurements have been made over the rapidity range 2.1 ≤ y ≤ 2.9 using the leadglass spectrometer of WA80. Within the statistical and systematical uncertainties the spectral shapes of π0 and η mesons yields are identical when their invariant differential cross section is plotted as a function of the transverse mass. The relative normalization of the η to π0 transverse mass spectra is found to be 0.53±0.07 for S+Au and 0.43±0.15 for S+S reactions. Extrapolation to full phase space leads to an integrated cross section ratio of η to π0 mesons of 0.147±0.017(stat.)±0.015(syst.), and 0.120±0.034(stat.)±0.022(syst.) for S+Au and S+S collisions, respectively.

Recent results from E802 and E859

Abstract The one- and two-neutron transfer reactions ( 14 C, 13 C) and ( 14 C, 12 C) have been measured on a series of targets. The angular distributions of the differential cross sections were analyzed in the DWBA approach. An excellent description of the one-neutron transfer angular distributions is obtained. The two-neutron transfer cross sections are shown to be underpredicted in DWBA by typically a factor of ten. A calculation which includes the two-step transfer process yields absolute magnitudes consistent with the observed differential transfer cross sections.