Emission times and opacities from interferometry in noncentral relativistic nuclear collisions

The nuclear overlap zone in noncentral relativistic heavy ion collisions is azimuthally very asymmetric. By varying the angle between the axes of defo rmation and the transverse direction of the pair momenta, the transverse Ha nbury-Brown-Twiss radii oscillate in a characteristic way. It is shown that these oscillations allow determination of source sizes, deformations, as w ell as the opacity and duration of emission of the source costed in any non central high energy nuclear collisions. The behavior of the physical quanti ties with centrality of the collisions is discussed-in particular, changes caused by a possible phase transition to a quark-gluon plasma.