Using the E609 calorimeter system, we have measured longitudinal energy flow in hard pA collisions which yield dijet final states. The mean laboratory energy flow into the nuclear target (backward) region, nlab < 2.83, minus the value for pp collisions is found to vary as A0.33 ± 0.12, and reaches a value of 50±8 GeV for Pb. The observed probability distribution of energy flow indicates that the energy transfer to a heavy nucleus seldom fluctuates to small values. We also find that the A dependence of the dijet production cross section depends sensitively upon the energy flow to the target region.
ASJC Scopus subject areas
- Nuclear and High Energy Physics