H. R. Bowman

PIONS PRODUCED NEAR THE CENTER-OF-MASS VELOCITY IN HEAVY-ION COLLISIONS

LBL-12585 Preprint i Submitted to Physical Review Letters i_.i PIONS PRODUCED NEAR THE CENTER-OF-MASS VELOCITY IN HEAVY-!ON COLLISIONS K.A. Frankel, J.A. Bistirlich, R. Bossingham, H.R. Bowman, K.M. Crowe, C.J .. Martoff, D. Murphy, J.O. Rasmussen, J.P. Sullivan, W.A. Zajc, J.P. Miller, 0. Hashimoto, M. Koike, J. P~ter, W. Benenson, G.M. Crawley, E. Kashy, J.A. Nolen, Jr., and J. Quebert August 1981 TWO-WEEK LOAN COPY This is a library Circulating Copy which may be borrowed for two weeks.· For a personal retention copy, call Tech. Info. Diu is ion, Ext. 6782 Prepared for the U.S. Department of Energy under Contract W-7405-ENG-48

MEASUREMENTS OF n-p CORRELATIONS IN THE REACTION OF RELATIVISTIC NEON WITH URANIUM

We report a preliminary measurement of coincident neutron-proton pairs emitted at 45° in the interaction of 400, 530, and 650 MeV/A neon beams incident on uranium. Charged particles were identified by time of flight and momentum, as determined in a magnetic spectrometer. Neutral particles were detected using a thick plastic scintillator, and their time of flight was measured between an entrance scintillator, triggered by a charged particle, and the neutron detector. The scatter plots and contour plots of neutron momentum vs. proton momentum appear to show a slight correlation ridge above an uncorrelated background. The projections of this plane on then-p momentum difference axis are essentially flat, showing a one standard deviation enhancement for each of the three beams energies. At each beam energy, the calculated momentum correlation function for the neutron-proton pairs is enhanced near zero neutron-proton momentum difference by approximately one standard deviation over the expected value for no correlation. This enhancement is expected to occur as a consequence of the attractive final state interaction between the neutron and proton (i.e., virtual or “singlet” deuterons). The implications of these measurements are discussed.