Shadowing Effects on Particle and Transverse Energy Production ∗

The proton and neutron structure functions are modified in the nuclear environment [1], referred to here as shadowing. In most shadowing models, such as gluon recombination, the structure function modifications should be correlated with the local nuclear density. The E745 experiment studied the spatial distribution of structure functions with νN interactions in emulsion [2]. They found evidence of a spatial dependence but could not determine the form. The spatial dependence of shadowing is reflected in particle production as a function of impact parameter, b, which may be inferred from the total transverse energy, ET , produced in a heavy ion collision [3]. At RHIC and LHC perturbative QCD processes are expected to be an important component of the total particle production. In particular, at early times, τi ∼ 1/pT ≤ 1/p0 ∼ 0.1 fm for p0 ∼ 2 GeV, semihard production of low pT minijets sets the stage for further evolution [4]. The average transverse energy of minijet production is proportional to the initial energy density and is the hard scattering contribution to the average total transverse energy. It is calculated within a specific detector acceptance (y). At leading order, the average transverse energy for a given minijet flavor, f , as a function of impact parameter is