Limits on Charmed-Particle Production in Proton-Nucleus Collisions at 400 GeV/c

Abstract

could not be completely ruled out in the GMR experiment, are negligible here because we use low-energy positrons and because the o-Ps is essentially free of the surface. All of the results, including the powder data, are consistent with a vacuum decay rate of 7.09±0.02 Lisec" 1 , (2.1 ±0.3)% below the theoretical value.The advances discussed in GMR and this work lead to many possibilities for future research. In particular, the high signal-to-noise ratio and good statistics of the present work should make possible a 200-ppm measurement of A when the systematic effects are fully understood. Moreover, our method of detecting the time of the o-Ps formation may allow consideration of a pulsed excitation to the excited states. The Ps-atom and Ps-surface scattering can also be investigated. To help define the limits on the future use of powders in precision measurements, an attempt to observe the Ps ground-state fine-structure splitting in our uncompressed powders is now underway in collaboration with W. Frieze

Nucleon-Number Dependence of Inclusive Dihadron Production in Proton-Nucleus Collisions at 400 GeV/c

“…Other results and a detailed description 5 Our kinematic correlation results are reported in D. A. Finley etal 8 The observation that heavier nuclei reduce quantumnumber correlations as well as kinematic correlations (see Finley et al t Ref. 2) is consistent with an inelastic multiple-scattering process. of the apparatus have been published previously.…”

“…of the apparatus have been published previously. 8 The apparatus consisted of two identical magnetic spectrometers placed at 100 mrad on opposite sides of the beam. In the proton-nucleon centerof-mass system, each spectrometer was centered at 6 = 110° and subtended about ± 10° in polar angle, and ± 17° in azimuth.…”

New limits on D0 (1.865) production in proton-nucleus collisions at 400 GeV/c

“…Our efforts have concentrated, in particular, on the search for D0(1.865) ~ 7rK, the particle observed in e+e -collisions [1] and presumably the carrier of the new quantum number associated with the J/~ family of particles. Early results from our experiment and a description of the apparatus have been presented elsewhere [2,3]. In this paper we give the final results of our search for new particles in 7r+K -and 7r-K ÷ mass spectra and give new limits on D O and D 0 production.…”

Two-Particle Quantum-Number Correlations in 400-GeV/cProton-Nucleus Collisions

“…Components of the apparatus and other results have been described elsewhere. 2 Briefly, the spectrometer was triggered by a coincidence of two charged particles which were produced near rapidity -0.4 in the proton-nucleon center-of-mass system, with transverse momenta p ± ^ 1 GeV/c, and with azimuthal separation near 180°. The target used for the data reported in this Letter consisted of thin, spatially separated segments of beryllium and lead.…”