Dimuon production below mass 3.1 GeV/c 2 in p-W and S-W interactions at 200 GeV/c/A

The focus of this experiment is on dimuons at low M_T but the mass range up to the {J}/{ψ} is also covered. Dimuons are measured over a wide rapidity interval, ranging from nearly central to very forward rapidities. Experimental results concerning the vector meson production in p-W and S-W interactions at 200 GeV/c/A as a function of the charged multiplicity are presented together with a comparison of the observed invariant mass spectra with the dimuon conventional sources in the mass region between the φ and {J}/{ψ} mesons. The observed large difference in the shape and absolute value of p-W and S-W dimuon spectra cannot be explained in terms of a direct extrapolation of the p-p results.