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First results are presented from BNL experiment E910 on pion production and stopping in proton-Be, Cu, and Au collisions at a beam momentum of 18 GeV/c. We characterize the centrality of the collisions using the measured number of grey tracks, Ngrey,and a derived quantity, nu, the number of inelastic nucleon-nucleon scatterings suffered by the projectile during the collision. We find that for the three targets the average backward rapidity shift of the leading proton follows a common trend versus nu with the projectile losing, on average, 2 units of rapidity in the first 2-3 scatterings. The average rapidity shift increases more slowly with subsequent scatterings reaching a maximum of 2.5 units. The pi- multiplicity measured within the E910 acceptance saturates with increasing nu in p-Au collisions while the pi- multiplicity in p-Be collisions increases faster with nu than expected from the wounded-nucleon model. Comparisons of our data with the RQMD cascade model suggest that in very central p-Au collisions most of the pions are produced near zero rapidity in the lab.
We analysed the $phi$ meson production in central Ni+Ni collisions at the beam kinetic energy of 1.93A GeV with the FOPI spectrometer and found the production probability per event of $[8.6 ~pm~ 1.6 ~(text{stat}) pm 1.5 ~(text{syst})] times 10^{-4}$.
The recent search for non $q bar{q}$ mesons in $pi^{-}p$ interactions at Brookhaven National Laboratory is summarized. Many final states such as $eta pi$, $eta pi^{-}$, $a_{0} pi$, $f_{1} pi$, $a_{2} pi$, $b_{1} pi$, which are favored decay modes of exotics, are under investigation.
We present transverse momentum (p_T) spectra of charged hadrons measured in deuteron-gold and nucleon-gold collisions at sqrts = 200 GeV for four centrality classes. Nucleon-gold collisions were selected by tagging events in which a spectator nucleon
The first detailed measurements of the centrality dependence of strangeness production in p-A collisions are presented. Lambda and Kshort dn/dy distributions from 17.5 GeV/c p-Au collisions are shown as a function of grey track multiplicity and the e
Measurements of charged pion and kaon production are presented in centrality selected Pb+Pb collisions at 40A GeV and 158A GeV beam energy as well as in semi-central C+C and Si+Si interactions at 40A GeV. Transverse mass spectra, rapidity spectra and