Measurement of the nuclear enhancement in high-Et and jet event production.

Abstract

Propertiea of eventa produced with high values of transverse energy (Et) in 800 GeV/c proton-nucleus collieions are presented. Both full-arimuth and limited aperture high Et triggers were wed to melect event6 from six targets (H, Be, C, Al, Cu, and Pb). The events were collected using the large acceptance Fermilab multiparticle spectrometer that recorded almost 95% of the incoming beam energy. The A dependence of the crow sectiona at a given Rt W(UI parameterixed M Aa . The value of a increases from 0.7 at low Et to a plateau at high Et of approximately 1.6. The high Et value of a is slightly amaller for the limited aperture triggers. A strong dependence of (1 on the event structure was observed; yet-like” events exhibit an A dependence consistent with a-1.0, while for more isotropic events a ia much larger. This observation is consistent with the expected behavior for jet production in pA colliaione. (a) Present address: Dept. of Physics, University of Michigan-Flint, Flint, MI 48502 (*) Present address: Inst. of Nucl. Physics, Novi Sad, Yugoslavia cc) Present address: Dept. of Physics, Univ. of Ariaona, Tucson AZ 85721 cd) Present address: A T & T Bell Laboratories, Naperville, IL, 80540 cc) Present address: Fermi National laboratory, Batavia, IL 60510 (f) Present address: Dept. of Physics, Univ. of Roeheater, NY 14267 (g) Present address: Tata Inst. of Fundamental Research, Bombay, India 400005