F. Plasil

A simple method of shower localization and identification in laterally segmented calorimeters

Abstract A method is proposed to calculate the first and second moments of the spatial distribution of the energy of electromagnetic and hadronic showers measured in laterally segmented calorimeters. The technique uses a logarithmic weightinh of the energy fraction observed in the individual detector cells. It is fast and simple requiring no fitting or complicated corrections for the position or angle of incidence. The method is demonstrated with GEANT simulations of a BGO detector array. The position resolution results and the c/gp separation results are found to be equal or superior to those obtained with more complicated techniques.

Azimuthal correlations between light particles emitted in 12O induced reactions on 12C and 197Au at 400 MeV

Abstract Azimuthal correlations between light particles emitted to polar angles of 40 and 70 degrees with respect to the beam axis were measured for 16 O induced reactions on 12 C and 197 Au at 400 MeV. Coincident light particles are preferentially emitted in a plane which contains the beam axis. For reactions on 12 C, coincident light particles are preferentially emitted to opposite sides of the beam axis. These correlations may be understood in terms of the phase constraints imposed by momentum conservation on systems with finite number of nucleons. For reactions on 197 Au, on the other hand, preferential emission of coincident deuterons and tritons to the same of the beam axis may be caused by the shadowing of preequilibrium particles by the adjacent cold spectator nuclear matter.

Azimuthal anisotropy of photon and charged particle emission in Pb-208+Pb-208 collisions at 158 center dot A GeV/c

The azimuthal distributions of photons and charged particles with respect to the event plane are investigated as a function of centrality in Pb-208 + Pb-208 collisions at 158 (.) A GeV/c in the WA98 experiment at the CERN SPS. The anisotropy of the azimuthal distributions is characterized using a Fourier analysis. For both the photon and charged particle distributions the first two Fourier coefficients are observed to decrease with increasing centrality. The observed anisotropies of the photon distributions compare well with the expectations from the charged particle measurements for all centralities.Abstract.The azimuthal distributions of photons and charged particles with respect to the event plane are investigated as a function of centrality in 208Pb + 208Pb collisions at 158

COMPARISON OF PI(0) AND ETA-SPECTRA FROM S + AU COLLISIONS AT 200 GEV/C

\cdot A

Collective Flow in 158 A GeV Pb + Pb Collisions

GeV/c in the WA98 experiment at the CERN SPS. The anisotropy of the azimuthal distributions is characterized using a Fourier analysis. For both the photon and charged particle distributions the first two Fourier coefficients are observed to decrease with increasing centrality. The observed anisotropies of the photon distributions compare well with the expectations from the charged particle measurements for all centralities.

Charge and mass distributions in strongly damped reactions of 58Ni+165Ho at 16 MeV/nucleon.

Neutral pi0 and eta spectra have been obtained over a wide transverse momentum range for various centralities of S + Au collisions at 200 GeV/nucleon. The analysis was done of the full statistics of the WA80 experiment at CERN using the two-photon invariant mass spectra. Compared to the previous analysis [1, 2] the pi0 and eta spectra were obntained over an extended p(t) range of 0.2 <p(t)(pi0) <4.4 GeV/c and 0.4 <p(t)(eta) <3.0 GeV/c.

Limits on the production of direct photons in 200A GeV S-32+Au collisions

Abstract Anisotropic transverse flow has been studied with a magnetic spectrometer at midrapidity and the Plastic Ball detector at target rapidity in the WA98 experiment. Our preliminary results show the existence of directed and elliptic flow in semi-central Pb+Pb collisions. The magnitude of the directed flow is found to be significantly smaller than those observed at the AGS energies.

Argon- and krypton-induced reactions at energies of 4--7 MeV/amu

Secondary charge and mass distributions have been measured for projectilelike fragments (PLFs) in strongly damped reactions of {sup 58}Ni+{sup 165}Ho at 16 MeV per nucleon bombarding energy. Statistical model evaporation calculations were compared with these distributions and with neutron multiplicities and temperatures for PLF and targetlike fragments (TLFs) to obtain the primary distributions prior to light-particle emission. The deduced primary distributions indicate a net transfer of protons to the target in contrast to the predictions of the nucleon transport exchange model, which predicts a net transfer of neutrons to the projectile. The results suggest an equal division of the available excitation energy at small total kinetic-energy (TKE) losses (up to 200 MeV) with thermal energy division occurring only at the largest TKE losses ({approx}325 MeV).