Dresden 2013 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 19: Hadronenstruktur und -spektroskopie
HK 19.1: Gruppenbericht
Montag, 4. März 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 Axx and Ayy 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 Cx,x and Cy,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 Ayp 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.