M. Torikoshi

100 cm long time-of-flight scintillation counters with rms resolution of 50 ps

Abstract We tested time-of-flight counters with four combinations of scintillators and photomultipliers. We examined two plastic scintillators (SCSN-23 and SCSN-38) and three 2 inch photomultipliers (R329, R1828 and R2083). The dimensions of both scintillators were 3.5 cm wide, 4 cm thick and 100 cm long. Time of flight was measured for minimum ionizing particles between a small scintillation counter and the test counter. We studied the dependence of the time resolution on the high voltage of the photomultiplier, and on the hit-position on the scintillator. The rms time resolution of 50 ps was achieved after software correction for a time-walk effect. The shape of the TOF spectra after the correction was found to remain a Gaussian distribution over three orders of magnitude. We also studied the dependence of TOF value on the hit-position, and found that most of the values at edges of the scintillator were 50–100 ps smaller than those at the center.

Recent results from E802 and E859

Abstract Recent single-particle inclusive measurements and two-particle correlation data from E802 and its succesor, E859, are presented. The K + / π + ratio observed for collisions of 14.6 A·GeV 28 Si ions on various targets is presented as a function of both forward and transverse energy. Source sizes are determined via interferometry using π + , π − , K + and proton pairs.

Antiproton production in 14.6 AGeVc Si+A collisions

Abstract Antiproton production cross sections have been measured for minimum bias and central Si+Al and Si+Au collisions at 14.6 A GeV c . The data presented cover the range of transverse momentum from 0.3 to 1.2 GeV c and lab rapidities from 1.1 to 1.7 units. The relative p π − and p K − yields are found to be the smallest for the heaviest system measured, central Si+Au collisions. For these collisions, the p π − ratio, determined from integrated yields for 1.1⩽y⩽1.7, is (0.84±0.07)×10−3. In the same rapidity interval, the average antiproton inverse m⊥ slope is 141±14 MeV for central Si+Al and central Si+Au collisions.

Particle production in pA and AA collisions at AGS

Production of light particles (π±,K±,p) has been measured in both Si+A and p+A collisions. Several interesting features have been observed, among which are: the enhanced K+/π+ ratio and the larger 〈mt〉 for K+ and proton. Comparisons between ≊pp, pA and SiA collisions are discussed.

Spectrometer results from BNL E802

Measurements of collisions of 14.5 GeV/c per nucleon 28Si ions with nuclear targets using the BNL E802 spectrometer are presented. A description of the experiment and preliminary particle ratios are discussed.