https://doi.org/10.1051/epjconf/20123701020
Near-threshold pion production in diproton reactions with polarised beams and target at ANKE-COSY
1 Physikalisches Institut II, Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
2 Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, 141980 Dubna, Russia
a e-mail: s.dymov@fz-juelich.de
An extensive experimental study of near-threshold pion production in diproton reactions is underway at the ANKE-COSY spectrometer (Jülich). The programme is aimed at isolating the four-nucleon-pion contact interaction term appearing in the XPT expansions of these processes. This will establish links between pion production and other low energy phenomena within the XPT approach. The first step in the programme was to measure the differential cross-section and the proton analysing power in the 
and 
reactions over the full angular range. Here {pp}s denotes a diproton, i.e., a two-proton system in a 1S0 state. These data allow a partial wave analysis to be carried out provided that simplifying assumptions are made when applying the Watson theorem. To make the analysis more robust, and independent of the uncertainties in the relative normalization, the spin-correlation coefficients Ax,x and Ay,y in the 
reaction were measured in a follow-up experiment. The first results of the data analysis are presented and future developments of the programme are outlined.
© Owned by the authors, published by EDP Sciences, 2012
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