J. C. Peng

Scattering of antiprotons from carbon at 46.8 MeV

Abstract Antiproton-carbon elastic and inelastic scattering cross sections have been measured at 46.8 MeV over an angular range 6° ⩽ θ ⩽ 59° with a magnetic spectrometer. Fits to the elastic and inelastic 4.44 MeV excited state cross sections put realistic limits on the strengths of the real and imaginary parts of the antiproton-carbon optical potential. The continuum cross section due to carbon break-up appears to be smaller than it is for corresponding proton data.

Parton Energy Loss Limits and Shadowing in Drell-Yan Dimuon Production

A precise measurement of the ratios of the Drell-Yan cross section per nucleon for an 800 GeV/{ital c} proton beam incident on Be, Fe, and W targets is reported. The behavior of the Drell-Yan ratios at small target-parton momentum fraction is well described by an existing fit to the shadowing observed in deep-inelastic scattering. The cross-section ratios as a function of the incident-parton momentum fraction set tight limits on the energy loss of quarks passing through a cold nucleus. {copyright} {ital 1999} {ital The American Physical Society}

Elastic scattering of antiprotons from Carbon Calcium and Lead at 180 MeV

Angular distributions for elastic scattering of 180 MeV antiprotons from 12C, 40Ca, and 208Pb have been measured over a wide angular range with a magnetic spectrometer. In general, microscopic calculations agree fairly well with the data. Optical-model fits with Woods-Saxon parametrization determine the magnitude and the relative strength of the real and imaginary potentials at the nuclear surface. When the shape of the potentials is derived from that of the charge distribution, the depth of the real potential is found to be shallow (30 MeV < V0 < 70 MeV). These results are in some disagreement with several models and predictions, but are consistent with the results of p-12C scattering at 46.8 MeV and with a recent a analysis of p-atom data.

Studies of hypernuclei by associated production

Abstract The spectroscopy of hypernuclei across a wide range of mass number has been studies by the associated production (π+, K+) technique. The energies of Λ single particle states in the s, p, d, and f shells have been determinedas a function of A. It is demonstrated that the (π+, K+) reaction is the method of choice for studying Λ-bound levels of hypernuclei.

Improved measurement of the anti-d / anti-u asymmetry in the nucleon sea

Measurements of the ratio of Drell-Yan yields from an 800 \rm{GeV/c} proton beam incident on liquid hydrogen and deuterium targets are reported. Approximately 360,000 Drell-Yan muon pairs remained after all cuts on the data. From these data, the ratio of anti-down (

Optical-model analysis of antiproton-nucleus elastic scattering at 50 and 180 MeV

\bar{d}

Energy loss of fast quarks in nuclei

) to anti-up (

Parton model versus color dipole formulation of the Drell-Yan process

\bar{u}

Deep-inelastic back-angle yields and orbiting in 28Si + 12C

) quark distributions in the proton sea is determined over a wide range in Bjorken-

One- and two-neutron transfer reactions with 14C

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