Measurement of the analyzing power in p-->d-->(p p)n with a fast forward 1S0 proton pair.
/ Authors
S. Yaschenko, S. Dymov, A. Kacharava, V. Komarov, G. Macharashvili, F. Rathmann, S. Barsov, R. Gebel, M. Hartmann, A. Khoukaz
and 21 more authors
P. Kulessa, A. Kulikov, V. Kurbatov., N. Lang, I. Lehmann, B. Lorentz, T. Mersmann, S. Merzliakov, S. Mikirtytchiants, A. Mussgiller, M. Nioradze, H. Ohm, D. Prasuhn, R. Schleichert, H. Seyfarth, E. Steffens, H. Stein, H. Ströher, Y. Uzikov, B. Zalikhanov, N. Zhuravlev
/ Abstract
A measurement of the analyzing power A(y) of the p-->d--> (p p) + n reaction was carried out at the ANKE spectrometer at COSY at beam energies of 0.5 and 0.8 GeV by detection of a fast forward proton pair of small excitation energy E(pp) < 3 MeV. The S-wave dominance in the fast diproton is experimentally demonstrated in this reaction. While at T(p) = 0.8 GeV the measured analyzing power almost vanishes, it rises to nearly unity at T(p) = 0.5 GeV for neutrons emitted at theta(c.m.)(n) = 167 degrees. The results are compared with a model taking into account one-nucleon exchange, single scattering, and Delta(1232) excitation in the intermediate state. The model describes fairly well the unpolarized cross section obtained earlier and the analyzing power at 0.8 GeV; it fails to reproduce A(y) at 0.5 GeV.
Journal: Physical review letters