Nuclear Transparency and Effective NN Cross Section in Heavy Ion Collisions at 14.6 GeV/nucleon

The probability of a projectile nucleon to traverse a target nucleus without interaction is calculated for central Si-Cu and Si-Pb collisions. Special attention is given to the impact parameter range which contributes to events with large transverse energy. A fit to the data from E814 requires an effective NN cross section of sigma_eff=54.2+-5.0mb (compared to the free space value sigma_in=30mb) and is interpreted as one related to wounded target nucleons.