PRODUCTION OF RHO-W AND S-U COLLISIONS AT 200 GEV NUCLEON(OMEGA AND PHI IN P)

The transverse mass differential cross-sections for the rho + omega an d phi resonances is obtained, in the central rapidity region, in p-W a nd S-U interactions at 200 GeV/nucleon. The measured rho + omega and p hi temperatures are similar to 15% higher in S-U as compared to p-W co llisions. The ratio of cross-sections times branching ratios into the dimuon channel B(phi)sigma(phi)/(B(rho)sigma(rho) + B(omega)sigma(omeg a)) is studied as a function of the energy density reached in the coll ision and of the dimuon transverse momentum, The measured ratio is 2 t o 3 times larger in S-U than in p-W collisions and an enhancement is o bserved in S-U interactions with increasing energy density.