CASTOR: A Forward Detector for the Identification of Centauro and Strangelets in Nucleus-Nucleus Collisions at the LHC

Presentation made at the XXVIIIth Symposium on Multiparticle Dynamics, 6-11 September 1998, Delphi and published in World ScientificThe physics motivation for a very forward detector to be employed in heavy ion collisions at the CERN LHC is discussed. A phenomenological model describing the formation and decay of a Centauro fireball in nucleus-nucleus collisions is presented. The CASTOR detector which is aimed to measure the hadronic and photonic content of an interaction and to identify deeply penetrating objects in the very forward, baryon-rich phase space 5.6eta7.2 in an event-by-event mode is described. Results of simulations of the expected response of the calorimeter and, in particular, to the passage of strangelets, are presented

Formation of Centauro in Pb+Pb Collisions at the LHC and their Identification in the ALICE Experiment

Presentation made at EPS-HEP'99 and submitted to IOP PublishingWe present a phenomenological model which describes the formation of a Centauro fireball in nucleus-nucleus interactions in the upper atmosphere and at the LHC, and its decay to non-strange baryons and strangeness-rich objects. We describe the CASTOR calorimeter for the ALICE experiment at the LHC. CASTOR will probe the very forward, baryon-rich phase space 5.6eta7.2 in 5.5xA TeV central Pb+Pb collisions. We present results of simulations for the response of CASTOR to the passage of strangeness-rich objects

Study of vector mesons in dimuon production in a large kinematic region in p-W and S-W interactions at 200 GeV/c/nucleon

Results are presented on $\rho+\omega$, $\phi$ and $J/\Psi$ production in p--W and $^{32}$S--W interactions at 200~GeV/c/nucleon measured via the dimuon decay in a large kinematic region. The data are normalized to the charged particle multiplicity in the same rapidity interval. They have been %CORR 1 obtained collected using the HELIOS/3 muon spectrometer at the CERN SPS. %CORR 2 and The ratio $\phi/{(\rho+\omega)}$ increases between proton and sulphur projectiles, and is further enhanced going from peripheral to central nucleus-nucleus interactions. This results from an increase in the number of produced $\phi$'s per charged particle. The increase in the ratio $\phi/{(\rho+\omega)}$ is not clearly dependent on p$_T$, but appears larger at higher rapidities, due to kinematic effects %CORR 3 and in conjunction with varying acceptance. $J/\Psi$ production, likewise normalized to charged multiplicity, is significantly lower in S--W compared to p--W interactions

Systematics of Inclusive Photon Production in 158 AGeV Pb Induced Reactions on Ni, Nb, and Pb Targets

The multiplicity of inclusive photons has been measured on an event-by-event basis for 158 AGeV Pb induced reactions on Ni, Nb, and Pb targets. The systematics of the pseudorapidity densities at midrapidity (rho_max) and the width of the pseudorapidity distributions have been studied for varying centralities for these collisions. A power law fit to the photon yield as a function of the number of participating nucleons gives a value of 1.13+-0.03 for the exponent. The mean transverse momentum, , of photons determined from the ratio of the measured electromagnetic transverse energy and photon multiplicity, remains almost constant with increasing rho_max. Results are compared with model predictions.Comment: 16 pages including 4 figure

Scaling of Particle and Transverse Energy Production in 208Pb+208Pb collisions at 158 A GeV

Transverse energy, charged particle pseudorapidity distributions and photon transverse momentum spectra have been studied as a function of the number of participants (N_{part}) and the number of binary nucleon-nucleon collisions (N_{coll}) in 158 A GeV Pb+Pb collisions over a wide impact parameter range. A scaling of the transverse energy pseudorapidity density at midrapidity as N_{part}^{1.08 \pm 0.06} and N_{coll}^{0.83 \pm 0.05} is observed. For the charged particle pseudorapidity density at midrapidity we find a scaling as N_{part}^{1.07 \pm 0.04} and N_{coll}^{0.82 \pm 0.03}. This faster than linear scaling with N_{part} indicates a violation of the naive Wounded Nucleon Model.Comment: 13 pages, 16 figures, submitted to European Physical Journal C (revised results for scaling exponents

Freeze-Out Parameters in Central 158AGeV Pb+Pb Collisions

Neutral pion production in central 158AGeV Pb+Pb collisions has been studied in the WA98 experiment at the CERN SPS. The pi0 transverse mass spectrum has been analyzed in terms of a thermal model with hydrodynamic expansion. The high accuracy and large kinematic coverage of the measurement allow to limit previously noted ambiguities in the extracted freeze-out parameters. The results are shown to be sensitive to the shape of the velocity distribution at freeze-out.Comment: 5 pages including 3 figures, small changes due to review process, accepted for publication in Phys.Rev.Let