Two-proton correlations from the 58Ni + 58Ni reaction at Einc = 876.5 MeV

This paper reports that in several recent paper, light-particle correlations have been used to obtain information on the size, lifetime, and temperature of the reaction zone in an energetic heavy-ion collision. The procedure is analogous to the well-known Hanbury-Brown-Twiss interferometer where photon-photon correlations with small relative momentum Δp (Δp = |(rvec p2 - rvec p1)/2|) were used to determine the size of stars. Owing to their nature, the interaction between the two correlated photons can be neglected. On the other hand, two nucleons correlated at small relative momentum will interact in the final state. In the model, it is the mechanism of final state interaction that yields information on the effective source size ρ, obtained as ρ = [r20 + (Vrel · τ)2]1/2, where r0 and τ are the emitter radius and lifetime, respectively. vrel is the velocity of the center of mass of the emitted pair of particles relative to the source. Obviously, the interpretation of the correlation function from the above model is unambiguous only in two limiting cases, i.e., for negligible particle