2019 Impact factor 2.176
Hadrons and Nuclei
Eur. Phys. J. A 9, 213-220

Role of multi-step processes in \ensuremath{\mathsf{^{16}O(^{11}B,^{12}C)^{15}N}} at 41.25 MeV

N. Ikeda1 - F. Nakamura1 - Y. Inotani1 - K. Koga1 - M. Koga1 - S. Koto1 - T. Sugimitsu1 - H. Fujita2 - S. Morinobu1

1 Department of Physics, Kyushu University, Fukuoka 812-8581, Japan
2 Daiichi College of Pharmaceutical Sciences, Fukuoka 815-8511, Japan
ikeda@kutl.kyushu-u.ac.jp

Received: 3 July 2000 / Revised version: 4 September 2000
Communicated by D. Guerreau

Abstract
The 16O(11B,12C)15N reaction at 41.25 MeV has been investigated using the kinematical coincidence method. Polarization tensors t20 and t40 of 12C[2+1] for the quantization axis taken along the direction of propagation have been measured at center-of-mass angles ( $\Theta_{\rm c.m.}$) between 48$^{\circ}$ and 62$^{\circ}$ by analyzing the energy spectrum of 12C[2+1] modulated by the effect of $\gamma$-ray emission. The cross-sections of the transfer reactions leading to the 12C[g.s.]+15N[g.s.], 12C[2+1]+15N[g.s.] and 12C[g.s.]+15N[3/2-1] final states have also been measured in the range 48$^{\circ}$ $\le$ $\Theta_{\rm c.m.}$ $\le$ 120$^{\circ}$. The polarization tensor terms of 12C[2+1] largely deviating from zero have been observed, contrary to the prediction by the distorted-wave Born approximation (DWBA). The one-step DWBA calculation also fails in describing the transfer reaction cross-sections. It is shown that the coupled channel model calculation including excitations and reorientations in 11B and 12C satisfactorily reproduces both the tensor terms and the cross-sections of the transfer reactions. The multi-step processes passing through the excited states of 11B are found to significantly contribute to the reaction.

PACS
25.70.Hi Transfer reactions - 24.70.+s Polarization phenomena in reactions - 24.10.Eq Coupled-channel and distorted-wave models


Copyright Società Italiana di Fisica, Springer-Verlag 2000