Abstract
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.
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We express appreciation to Fred Lothrop and the crew of the Bevalac for making these experiments possible.
We thank T. Humanic for helpful conversations.
W.J. McDonald would like to acknowledge J.O. Rasmussen and W. Schimmerling for their hospitality and support and to the National Sciences and Engineering Research Council of Canada for support.
This work was supported by the Director, Office of Energy Research, Division of Nuclear Physics of the Office of High Energy and Nuclear Physics, and also in part by the Director, Office of Energy, Health, and Environmental Research, of the U.S. Department of Energy under Contract DE-AC03-76SF00098 and by the National Aeronautics and Space Administration.
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Frankel, K., Schimmerling, W., Rasmussen, J.O. et al. Measurements ofn−p correlations in the reaction of relativistic neon with uranium. Z. Physik A - Atomic Nuclei 323, 391–398 (1986). https://doi.org/10.1007/BF01313520
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DOI: https://doi.org/10.1007/BF01313520