Ig. Bearden et al., PROTON AND ANTIPROTON DISTRIBUTIONS AT MIDRAPIDITY IN PROTON-NUCLEUS AND SULFUR-NUCLEUS COLLISIONS, Physical review. C. Nuclear physics, 57(2), 1998, pp. 837-846
Experiment NA44 has measured proton and antiproton distributions at mi
drapidity in sulphur and proton collisions with nuclear targets at 200
and 450 GeV/c per nucleon respectively. The inverse slopes of transve
rse mass distributions increase with system size for both protons and
antiprotons but are slightly lower for antiprotons. This could happen
if antiprotons are annihilated in the nuclear medium. The antiproton y
ield increases with system size and centrality and is largest at midra
pidity. The proton yield also increases with system size and centralit
y, but decreases from backward rapidity to midrapidity. The stopping o
f protons at these energies lies between the full stopping and nuclear
transparency scenarios. The data are in reasonable agreement with RQM
D predictions except for the antiproton yields from sulphur-nucleus co
llisions.