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Spin-triplet final-state dominance in the pp -> pn pi+ reaction at 492 MeV

V. Abaev·M. Buescher·S. Dymov·M. Hartmann·A. Kacharava·V. I. Komarov·V. Koptev·V. Kurbatov·S. Mikirtychiants·M. Nekipelov·A. Petrus·H. Stroeher·Yu. N. Uzikov·C. Wilkin·S. Yaschenko
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Abstract

The near-forward cross section for the pp -> pn pi^+ reaction has been measured at 492 MeV by using the large acceptance ANKE magnetic spectrometer placed at an internal target position of the storage ring COSY-Juelich. Protons and pions emitted near zero degrees were detected in coincidence, and those with theta_pi <= 2 degrees and theta_p <= 2.5degrees were subjected to detailed analysis. Under these conditions, the excitation energy in the np system was below 3 MeV over the measured momentum range. This is the region of the np final-state-interaction peak, which was measured with a resolution of a fraction of an MeV. The shape of the peak allows one to conclude that the fraction of final spin-singlet np pairs is below about 10%. By using the results of scattering theory, this limit is confirmed through a comparison with the cross section for pp -> d pi^+. The smallness of the singlet contribution is consistent with trends seen in lower energy data.

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V. Abaev, M. Buescher, S. Dymov, M. Hartmann, A. Kacharava, V. I. Komarov, V. Koptev, V. Kurbatov, S. Mikirtychiants, M. Nekipelov, A. Petrus, H. Stroeher, Yu. N. Uzikov, C. Wilkin, S. Yaschenko. 2001-09-13. Spin-triplet final-state dominance in the pp -> pn pi+ reaction at 492 MeV. https://doi.org/10.1016/s0370-2693(01)01229-1

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