A. Bamberger

Construction and beam test of the ZEUS forward and rear calorimeter

Abstract The forward and rear calorimeters of the ZEUS experiment are made of 48 modules with maximum active dimensions of 4.6 m height, 0.2 m width, 7 λ depth and maximum weight of 12 t. It consists of 1 X 0 uranium plates interleaved with plastic scintillator tiles read out via wavelength shifters and photomultipliers. The mechanical construction, the achieved tolerances as well as the optical and electronics readout are described. Ten of these modules have been tested with electrons, hadrons and muons in the momentum range 15–100 GeV/ c . Results on resolution, uniformity and calibration are presented. Our main result is the achieved calibration accuracy of about 1% obtained by using the signal from the uranium radioactivity.

Recent results from the NA35 collaboration at CERN

Abstract Recent results from the NA35 Collaboration are presented for the reactions of 60 and 200 GeV/nucleon p and 16 O, and 200 GeV/nucleon 32 S with various targets ranging from S to Au. Midrapidity transverse energy distributions and forward energy flow, p⊥ spectra and rapidity distributions of hadrons are presented. Two-pion interferometry results are discussed. Neutral strange particle yields and p⊥ distributions are presented. Conclusions are drawn from the experimental results.

Negative particle production in nuclear collisions at 60 and 200 GeV/nucleon

The results on spectra of negative particles produced in16O+Au andp-Au collisions at 200 GeV/nucleon and16O+Au at 60 GeV/nucleon are presented. The correlations of average rapidity and average transverse momentum with event multiplicity are studied. Spectral shapes are similar for central16O+Au andp-Au collisions. The transverse momentum and rapidity distributions for central16O+Au andp-Au collisions differ strongly from corresponding distributions forp+p interactions. The FRITIOF model fails to describe the shapes of the transverse momentum distributions. The simple thermodynamical model of a single fireball does not fit the midrapidity transverse momentum distributions, and the rapidity distributions.

The small angle rear tracking detector of ZEUS

Abstract The design, construction, installation, and performance of the small angle rear tracking detector of the ZEUS experiment are described. The results on electron position measurement, electron energy correction, and background reduction at the first-level trigger are presented. The impact on the measurement of the proton structure function is discussed.

Experimental study of uranium plastic scintillator calorimeters

Abstract As a preparation for the ZEUS high resolution calorimeter, sampling calorimeters made from 3.2 mm plates of depleted uranium read out by plastic scintillator of 3 mm and 5 mm thickness have been built. The response of hadrons, electrons and muons has been measured in the energy range between 3 and 100 GeV. In agreement with predictions, the relative response of electrons and hadrons as well as the hadronic energy resolution depend strongly on the thickness of the plastic scintillator. For 3.2 mm depleted uranium and 3 mm thick scintillator we observe over the full energy range equal response for electrons and hadrons; a hadronic energy resolution of 34.5% E[ GeV ] is obtained. Results are given for the spatial resolution for electrons and hadrons. Finally, results from a lead scintillator calorimeter built as a prestudy before uranium plates were available are reported.

Charged particle multiplicities and inelastic cross sections in high energy nuclear collisions

Abstract Inelastic cross sections at 60 and 200 GeV/nucleon are determined in a streamer chamber for 16 O on several nuclear targets. Charged particle multiplicity distributions for inelastic and central collisions are studied and compared with theoretical predictions. The inelastic cross section exhibit a geometrical dependence on nuclear radii. The multiplicity data are governed by the collision geometry. They are consistent with a picture of superposition of independent nucleon-nucleus interactions.

Negative Particle Production in Nuclear Collisions at 60-GeV/Nucleon and 200-GeV/Nucleon

The results on spectra of negative particles produced in16O+Au andp-Au collisions at 200 GeV/nucleon and16O+Au at 60 GeV/nucleon are presented. The correlations of average rapidity and average transverse momentum with event multiplicity are studied. Spectral shapes are similar for central16O+Au andp-Au collisions. The transverse momentum and rapidity distributions for central16O+Au andp-Au collisions differ strongly from corresponding distributions forp+p interactions. The FRITIOF model fails to describe the shapes of the transverse momentum distributions. The simple thermodynamical model of a single fireball does not fit the midrapidity transverse momentum distributions, and the rapidity distributions.

The presampler for the forward and rear calorimeter in the ZEUS detector

Abstract The ZEUS detector at HERA has been supplemented with a presampler detector in front of the forward and rear calorimeters. It consists of a segmented scintillator array read out with wavelength-shifting fibers. We discuss its design, construction and performance. Test beam data obtained with a prototype presampler and the ZEUS prototype calorimeter demonstrate the main function of this detector, i.e. the correction for the energy lost by an electron interacting in inactive material in front of the calorimeter.

The ZEUS forward plug calorimeter with lead scintillator plates and WLS fiber readout

A Forward Plug Calorimeter (FPC) for the ZEUS detector at HERA has been built as a shashlik lead–scintillator calorimeter with wave length shifter fiber readout. Before installation it was tested and calibrated using the X5 test beam facility of the SPS accelerator at CERN. Electron, muon and pion beams in the momentum range of 10–100 GeV/c were used. Results of these measurements are presented as well as a calibration monitoring system based on a 60Co source.

Measurement ofπ0production at large transverse momentum inπ−p,π+p, andppcollisions at 300 GeV/c

Cross sections for inclusive ..pi../sup 0/ production at large transverse momentum p/sub T/ were measured in ..pi../sup -/p, ..pi../sup +/p, and pp collisions at 300 GeV/c. The cross-section ratio sigma(..pi../sup -/p..--> pi../sup 0/X)/sigma(..pi../sup +/p..--> pi../sup 0/X) was found to be consistent with unity in the p/sub T/ region of 1 to 5 GeV/c. The cross-section ratio sigma(..pi../sup +/p..--> pi../sup 0/X)/sigma(pp..--> pi../sup 0/X) however is growing with increasing p/sub T/ and increasing ..pi../sup 0/ c.m.-system rapidity in agreement with parton-model expectations, where the partons in the pions have on average higher momenta than in the proton.