https://doi.org/10.1140/epja/i2005-10185-0
Original Article
Near-threshold η-meson production in the dd↦He η reaction
1
Institut für Kernphysik, Forschungszentrum Jülich, 52425, Jülich, Germany
2
Institute of Physics, Jagiellonian University, Reymonta 4, 30-059, Cracow, Poland
3
Physics Department, University College London, WC1E 6BT, London, UK
4
Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, 141980, Dubna, Russia
5
Institut für Kernphysik, Universität Münster, 48149, Münster, Germany
6
High Energy Physics Department, PNPI, 188350, Gatchina, Russia
Received:
21
October
2005
Accepted:
14
December
2005
Published online:
27
December
2005
The dd↦4 Heη reaction has been investigated near threshold using the ANKE facility at COSY-Jülich. Both total and differential cross-sections have been measured at two excess energies, Q = 2.6 MeV and 7.7 MeV, with a subthreshold measurement being undertaken at Q = - 2.6 MeV to study the physical background. While consistent with isotropy at the lower energy, the angular distribution reveals a pronounced anisotropy at the higher one, indicating the presence of higher partial waves. Options for the decomposition into partial amplitudes and their consequences for the determination of the s-wave ηα scattering length are discussed.
PACS: 13.60.Le Meson production – / 25.10.+s Nuclear reactions involving few-nucleons systems – / 25.45.-z 2H-induced reactions – / 11.80.Et Partial-wave analysis –
© Società Italiana di Fisica and Springer-Verlag, 2006
