The double differential cross sections at lab between 0.0°and 12.3°and the polarization transfer D NN at 0°for the 90 Zr(p,n) reaction are measured at a bombarding energy of 295 MeV. A multipole decomposition technique is applied to the cross sections to extract Lϭ0, Lϭ1, Lϭ2, and Lϭ3 contributions. The Gamow-Teller ͑GT͒ strength B(GT) in the continuum deduced from the Lϭ0 cross section is compared both with the perturbative calculation by Bertsch and Hamamoto and with the second-order random phase approximation calculation by DroSdS et al. The sum of B(GT) values up to 50 MeV excitation becomes S ␤ Ϫϭ28.0Ϯ1.6 after subtracting the contribution of the isovector spin-monopole strength. This S ␤ Ϫ value of 28.0Ϯ1.6 corresponds to about ͑93 Ϯ 5͒% of the minimum value of the sum rule 3(NϪZ)ϭ30. The usefulness of the polarization transfer observable in the distorted wave impulse approximation is presented. ͓S0556-2813͑97͒02006-2͔

The cross sections for single-neutron removal from the very neutron-rich nucleus 31Ne on Pb and C targets have been measured at 230 MeV/nucleon using the RIBF facility at RIKEN. The deduced large Coulomb breakup cross section of 540(70) mb is indicative of a soft E1 excitation. Comparison with direct-breakup model calculations suggests that the valence neutron of 31Ne occupies a low-l orbital (most probably 2p(3/2)) with a small separation energy (S(n) approximately < 0.8 MeV), instead of being predominantly in the 1f(7/2) orbital as expected from the conventional shell ordering. These findings suggest that 31Ne is the heaviest halo system known.

No abstract

No abstract

The cross section, the deuteron vector A(d)(y) and tensor analyzing powers A(ij), the polarization transfer coefficients K(y('))(ij), and the induced polarization P(y(')) were measured for the dp elastic scattering at 270 MeV. The cross section and A(d)(y) are well reproduced by Faddeev calculations with modern data-equivalent nucleon-nucleon forces plus the Tucson-Melbourne three-nucleon force. In contrast, A(ij), K(y('))(ij), or P(y(')) are not described by such calculations. These facts indicate the deficiencies in the spin dependence of the Tucson-Melbourne force and call for extended three-nucleon force models.