S. Amato

Enhanced leading production of D+- and D*+- in 250-GeV pi+- - nucleon interactions

A leading charm meson is one with longitudinal momentum fraction, [ital x][sub [ital F]][gt]0, whose light quark (or antiquark) is of the same type as one of the quarks in the beam particles. We report on the production asymmetry, [ital A]=[[sigma](leading[minus][sigma](nonleading)]/[[sigma](leading)+[sigma](nonleading)] as a function of [ital x][sub [ital F]]. The data consist of 1500 fully reconstructed [ital D][sup [plus minus]] and [ital D][sup *[plus minus]] decays in Fermilab experiment E 769. We find a significant asymmetry for the production of charm quarks is not expected in perturbative quantum chromodynamics.

The E791 parallel architecture data acquisition system

Abstract To collect data for the study of charm particle decays, we built a high speed data acquisition system for use with the E791 magnetic spectrometer at Fermilab. The DA system read out 24000 channels in 50 μs. Events were accepted at the rate of 9000 per second. Eight large FIFOs were used to buffer event segments, which were then compressed and formatted by 54 processors housed in six VME crates. Data was written continuously to 42 Exabyte tape drives at the rate of 9.6 Mb/s. During the 1991 fixed target run at Fermilab, 20 billion physics events were recorded on 24000 8 mm tapes; this 50 Tb (Terabyte) data set is now being analyzed.

Atomic mass dependence ofΞ−andΞ¯+production in central 250 GeVπ−-nucleon interactions

We present the first measurement of the atomic mass dependence of central Ξ− and Ξ + production. It is measured using a sample of 22,459 Ξ−’s and Ξ + ’s produced in collisions between a 250 GeV π− beam and targets of beryllium, aluminum, copper, and tungsten. The relative cross sections are fit to theWe present the first measurement of the atomic mass dependence of central \Xi^- and \overline{\Xi}^+ production. It is measured using a sample of 22,459 \Xi^-s and \overline{\Xi}^+s produced in collisions between a 250 GeV \pi^- beam and targets of beryllium, aluminum, copper, and tungsten. The relative cross sections are fit to the two parameter function \sigma_0 A^\alpha, where A is the atomic mass. We measure \alpha = 0.924+-0.020+-0.025, for Feynman-x in the range -0.09