Measurement of the nuclear enhancement in high-Etand jet event production

Abstract

Properties of events produced with high values of transverse energy (${E}_{t}$) in 800-GeV/c proton-nucleus collisions are presented. Both full-azimuth and limited-aperture high-${E}_{t}$ triggers were used to select events 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 cross sections at a given ${E}_{t}$ was parametrized as ${A}^{\ensuremath{\alpha}}$. The value of \ensuremath{\alpha} increases from 0.7 at low ${E}_{t}$ to a plateau at high ${E}_{t}$ of approximately 1.6. The high-${E}_{t}$ value of \ensuremath{\alpha} is slightly smaller for the limited-aperture triggers. A strong dependence of \ensuremath{\alpha} on the event structure is observed; ``jetlike'' events exhibit an A dependence consistent with \ensuremath{\alpha}\ensuremath{\approxeq}1.0, while for more isotropic events \ensuremath{\alpha} is much larger. This observation is consistent with the expected behavior for jet production in pA collisions.

Abstract

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