Nuclear transparencies measured in exclusive incoherent ρ0 meson production from hydrogen, deuterium, carbon, calcium, and lead in muon-nucleus scattering are reported. The data were obtained with the E665 spectrometer using the Fermilab Tevatron muon beam with a mean beam energy of 470 GeV. Increases in the nuclear transparencies are observed as the virtuality of the photon increases, in qualitative agreement with the expectations of color transparency.
Measurements of the suppression of the yield per nucleon of J/Psi and Psi' production for 800 GeV/c protons incident on heavy relative to light nuclear targets have been made with very broad coverage in xF and pT. The observed suppression is smallest at xF values of 0.25 and below and increases at larger values of xF. It is also strongest at small pT. Substantial differences between the Psi' and J/Psi are observed for the first time in p-A collisions. The suppression for the Psi' is stronger than that for the J/Psi for xF near zero, but becomes comparable to that for the J/Psi for xF > 0.6.
We have measured cross sections for forward neutron production from a variety of targets using proton beams from the Fermilab Main Injector. Measurements were performed for proton beam momenta of 58 GeV/c, 84 GeV/c, and 120 GeV/c. The cross section dependence on the atomic weight (A) of the targets was found to vary as $A^(alpha)$ where $\alpha$ is $0.46\pm0.06$ for a beam momentum of 58 GeV/c and 0.54$\pm$0.05 for 120 GeV/c. The cross sections show reasonable agreement with FLUKA and DPMJET Monte Carlos. Comparisons have also been made with the LAQGSM Monte Carlo.