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Proton-Proton Scattering with ANKE

A thorough understanding of the nucleon-nucleon (NN) interaction remains one of the principal goals of nuclear and hadronic physics. For the study of nuclear forces, elastic NN scattering data are necessary ingredients in the modeling of meson production and other nuclear reactions at intermediate energies. It is incumbent on any facility that can make a significant and new contribution to this important database of knowledge. A new important data set was now provided by the ANKE experiment.

pp elastic scatteringCopyright: ANKE Collaboration

The new experiment at COSY-ANKE was performed in April 2013 using a polarized proton beam at six different beam energies of Tp = 0.8, 1.6, 1.8, 2.0, 2.2, 2.4 GeV that interacted with a hydrogen cluster-jet target. Elastic pp scattering events were identified by detecting one or both of the final protons in the Forward Detector and/or the Silicon Tracking Telescopes of ANKE. The beam polarizations were measured in parallel of ANKE data taking by using the EDDA detection system as a polarimeter. Preliminary results on the proton analysing power Ay from these measurements are presented in the figure above. The results are compared to the available world data base and the SAID predictions. Excellent agreement is found between the ANKE results and the published data at 0.8 GeV, where there is little ambiguity in the experimental results or the partial wave analysis. At higher beam energies, however, the current SAID PWA solution 2007 doesn't describe the ANKE data. Analysis is in progress and final results with total errors of better than 5% are expected.

For further details see Annual Report 2013.