Discovery of jet quenching at RHIC and the opacity of the produced gluon plasma

The predicted quenching of jets in A + A at RHIC energies has been discovered by STAR and PHENIX in preliminary data reported at this conference. We apply the GLV theory [1] of QCD radiative energy loss to estimate the opacity, L/lambda(g), of the gluon plasma produced in Au + Au collisions at 130 AGeV. We show that (in contrast to the factor of two Cronin enhancement of pi(0) found at the SPS by WA98) the factor of 5-8 suppression of p(T) similar to 2 - 4 GeV pi(0) reported by PHENIX [2] can be accounted for with an effective static plasma opacity L/lambda(g) approximate to 3 - 4