Refereed Publications

1. T. Wakasa, Y. Hagihara, T. Noro, T. Ishida, S. Asaji, Y. Nagasue, K. Hatanaka, Y. Sakemi, A. Tamii, Y. Shimizu, K. Fujita, Y. Tameshige, H. Sakai, H. Kuboki, M. Sasano, M. Ichimura, H. Kamada, M. Yamaguchi, “Isovector effective NN interaction in ²⁸Si(p, n)²⁸P(6-) at 198 MeV,” in Physics Letters, B645, (2007) pp. 402-407.
   Abstract - We report measurements of the cross section and a complete set of polarization observables for the ²⁸Si(p,n)²⁸P(6-) reaction at a bombarding energy of 198 MeV. The data are compared with distorted wave impulse approximation calculations employing response functions normalized to inelastic electron scattering. The spin-longitudinal polarized cross section ID_q is slightly over-predicted by the calculations, while the normal spin-transverse polarized cross section ID_n is significantly under-predicted. The calculated in-plane spin-transverse ID_p and spin-scalar ID₀ polarized cross sections agree well with the experimental data. These results are consistent with those for ²⁸Si(p,p')²⁸Si(6-, T = 1) scattering at the same energy, and thus it is concluded that isospin-mixing effects are not responsible for the discrepancy between theory and experiment in the (p,p') case. Energy half-off-shell effects as medium effects on the effective nucleon-nucleon interaction are also investigated and found to be too small to be responsible for the discrepancy.
2. T. Wakasa, M. Dozono, E. Ihara, S. Asaji, K. Fujita, K. Hatanaka, M. Ichimura, T. Ishida, T. Kaneda, H. Matsubara, Y. Nagase, T. Noro, Y. Sakemi, Y. Shimizu, H. Takeda, Y. Tameshige, A. Tamii, Y. Yamada, “Study of nuclear correlation effects via ¹²C(p,n) ¹²N(g.s.,1⁺) at 296 MeV,” in Physics Letters, B 656, (2007) pp.38-44.
   Abstract - We report measurements of the cross section and a complete set of polarization observables for the Gamow-Teller ¹²C(p,n)¹²N(g.s., 1⁺) reaction at a bombarding energy of 296 MeV. The data are compared with distorted wave impulse approximation calculations employing transition form factors normalized to reproduce the observed beta-decay ft value. The cross section is significantly under-predicted by the calculations at momentum transfers q≧0.5fm^-1. The discrepancy is partly resolved by considering the non-locality of the nuclear mean field. However, the calculations still under-predict the cross section at large momentum transfers of q≒1.6fm^-1. We also performed calculations employing random phase approximation response functions and found that the observed enhancement can be attributed in part to pionic correlations in nuclei.

>PAGE TOP