https://doi.org/10.1140/epja/i2013-13049-0
Regular Article - Experimental Physics
The neutron-proton charge-exchange amplitudes measured in the dp → ppn reaction
19878
High Energy Physics Institute, Tbilisi State University, GE-0186, Tbilisi, Georgia
29878
Institut für Kernphysik and Jülich Centre for Hadron Physics, Forschungszentrum Jülich, D-52425, Jülich, Germany
39878
High Energy Physics Department, Petersburg Nuclear Physics Institute, RU-188350, Gatchina, Russia
49878
Institut de Physique Nucléaire, Université Paris-Sud, IN2P3-CNRS, F-91406, Orsay Cedex, France
59878
Laboratory of Nuclear Problems, JINR, RU-141980, Dubna, Russia
69878
Physikalisches Institut II, Universität Erlangen-Nürnberg, D-91058, Erlangen, Germany
79878
Laboratory of High Energies, JINR, RU-141980, Dubna, Russia
89878
Institut für Kernphysik, Universität Münster, D-48149, Münster, Germany
99878
Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056, Basel, Switzerland
109878
H. Niewodniczański Institute of Nuclear Physics PAN, PL-31342, Kraków, Poland
119878
Institut für Kern- und Hadronenphysik, Forschungszentrum Rossendorf, D-01314, Dresden, Germany
129878
Department of Physics, M. V. Lomonosov Moscow State University, RU-119991, Moscow, Russia
139878
Physics and Astronomy Department, UCL, Gower Street, WC1E 6BT, London, UK
* e-mail: c.wilkin@ucl.ac.uk
Received:
11
December
2012
Accepted:
1
April
2013
Published online:
22
April
2013
The unpolarised differential cross section and the two deuteron tensor analysing powers A
xx
and A
yy
of the 
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 2.27GeV, 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 2.27GeV, 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 C
x,x
and C
y,y
that were carried out in the 
reaction at 1.2 and 2.27GeV. The values obtained for the proton analysing power A
y
p
also suggest the need for a radical re-evaluation of the neutron-proton elastic scattering amplitudes at the higher energy. It is therefore clear that such measurements can provide a valuable addition to the neutron-proton database in the charge-exchange region.
© SIF, Springer-Verlag Berlin Heidelberg, 2013
