title: Measurements of n-p correlations in the reaction of relativistic neon with uranium.
abstract: We report a preliminary measurement of coincident neutron-proton pairs emitted at 45 degrees 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 the n-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.
authors.affiliation: Lawrence Berkeley Laboratory, University of California, Berkeley, USA.
authors.forename: K
authors.initials: K
authors.lastname: Frankel
authors.forename: W
authors.initials: W
authors.lastname: Schimmerling
authors.forename: J O
authors.initials: JO
authors.lastname: Rasmussen
authors.forename: K M
authors.initials: KM
authors.lastname: Crowe
authors.forename: J
authors.initials: J
authors.lastname: Bistirlich
authors.forename: H
authors.initials: H
authors.lastname: Bowman
authors.forename: O
authors.initials: O
authors.lastname: Hashimoto
authors.forename: D L
authors.initials: DL
authors.lastname: Murphy
authors.forename: J
authors.initials: J
authors.lastname: Ridout
authors.forename: J P
authors.initials: JP
authors.lastname: Sullivan
authors.forename: E
authors.initials: E
authors.lastname: Yoo
authors.forename: W J
authors.initials: WJ
authors.lastname: McDonald
authors.forename: M
authors.initials: M
authors.lastname: Salomon
authors.forename: J S
authors.initials: JS
authors.lastname: Xu
mesh_terms: D004601:Elementary Particles; D008962:Models, Theoretical; D009356:Neon; D009502:Neutrons; D009686:Nuclear Physics; D011522:Protons; D013053:Spectrophotometry / Q000379:methods; D014501:Uranium
chemical_list: D011522:Protons; D014501:Uranium; D009356:Neon