Dresden 2013 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 19: Hadronenstruktur und -spektroskopie

HK 19.1: Group Report

Monday, March 4, 2013, 16:45–17:15, HSZ-105

The neutron-proton charge-exchange amplitudes measured in the dp → ppn reaction at ANKE/COSY — •David Mchedlishvili — Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany — High Energy Physics Institute, Tbilisi State University, 0186 Tbilisi, Georgia

The unpolarised differential cross section and the two deuteron tensor analysing powers A_xx and A_yy of the "017Edp → {pp}_sn charge-exchange reaction have been measured with the ANKE spectrometer at the COSY storage ring. Using deuteron beams with energies 1.2, 1.6, 1.8, and 2.27 GeV, data were obtained for small momentum transfers to a {pp}_s system with low excitation energy. The results at the three lower energies are consistent with impulse approximation predictions based upon the current knowledge of the neutron-proton amplitudes. However, at 2.27 GeV, where these amplitudes are far more uncertain, agreement requires a reduction in the overall double-spin-flip contribution, with an especially significant effect in the longitudinal direction. These conclusions are supported by measurements of the deuteron-proton spin-correlation parameters C_x,x and C_y,y that were carried out in the "017Ed "017Ep → {pp}_sn reaction at 1.2 and 2.27 GeV. The values obtained for the proton analysing power A_y^p also suggest the need for a radical re-evaluation of the neutron-proton elastic scattering amplitudes at the higher energy. Such measurements can provide a valuable addition to the neutron-proton database in the charge-exchange region.

Supported by the COSY-FFE program.