D. Errede

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.

Use of a transition radiation detector in a beam of high energy hadrons

Abstract A transition radiation detector (TRD) comprised of 24 identical radiator plus xenon proportional chamber assemblies was built at Fermilab and operated successfully to separate pions from protons and kaons in a 250 GeV incident hadron beam ( γ π ∼ 1800) at rates up to, and sometimes even exceeding, 2 MHz. The detector was capable of identifying pions with efficiencies exceeding 90% and with ≤ 3% contamination due to the nearly equally copious protons and kaons in the beam.

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

Design and performance characteristics of the E769 beamline transition radiation detector

A transition radiation detector (TRD) was designed and built for E769, a Fermilab fixed target experiment for use in separating pions from protons or kaons in a 250-GeV/c positive beam at the Tagged Photon Laboratory. Requirements placed on the detector were that it operate in a high rate ( approximately=2 MHz) environment and that it be relatively easy to build since it had to be ready approximately one year from the date of its inception. The short time available precluded exposing prototypes to a test beam, making it necessary to rely on source testing and Monte Carlo programs to predict the detector performance. When operated in the beam, the detector performance was in good agreement with these predictions. For a pion detection efficiency of 87%, the contamination by protons of a sample of TRD tagged pions was 2%. >