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The vector analyzing power has been measured for the elastic scattering of neutron-rich He from polarized protons at 71 MeV/nucleon. Two approaches based on local one-body potentials were applied to investigate the spin-orbit interaction between a proton and a He nucleus. An optical model analysis revealed that the spin-orbit potential for He is characterized by a shallow and long-ranged shape compared with the global systematics of stable nuclei. A semi-microscopic analysis with a α + n + n cluster folding model suggests that the inclusion of realistic interaction between a proton and the α core is important in describing the p-He elastic scattering. [ABSTRACT FROM AUTHOR]

Elastic and inelastic alpha scatterings on 10C were measured using a 68-MeV/u radioactive 10C beam incident on the recently developed MAIKo active target system. The phenomenological effective α-N interaction and the point-nucleon density distribution in the ground state were determined from the elastic scattering data. The cross sections of the inelastic alpha scattering were calculated using this interaction and density distribution and were compared with the experiment to determine the neutron quadrupole transition matrix element Mn between the ground state and the 2+1 state at Ex=3.35 MeV in 10C. The deduced neutron transition matrix element is Mn=6.9±0.7(fit)±1.2(sys)fm². The ratio of the neutron transition strength to proton transition strength was determined as Mn/Mp=1.05±0.11(fit)±0.17(sys), which indicates that the quadrupole transition between the ground state and the 2+1 state in 10C is less neutron dominant compared to that in 16C. [ABSTRACT FROM AUTHOR]

The isospin characters of low-energy dipole excitations in neutron-rich unstable nucleus 20 O were investigated, for the first time in unstable nuclei. Two spectra obtained from a dominant isovector probe ( O 20 + Au ) and a dominant isoscalar probe ( O 20 + α ) were compared and analyzed by the distorted-wave Born approximation to extract independently the isovector and isoscalar dipole strengths. Two known 1 − states with large isovector dipole strengths at energies of 5.36(5) MeV ( 1 1 − ) and 6.84(7) MeV ( 1 2 − ) were also excited by the isoscalar probe. These two states were found to have different isoscalar dipole strengths, 2.70(32)% ( 1 1 − ) and 0.67(12)% ( 1 2 − ), respectively, in exhaustion of the isoscalar dipole-energy-weighted sum rule. The difference in isoscalar strength indicated that they have different underlying structures. [ABSTRACT FROM AUTHOR]

Abstract: We have measured the 16O(p, d) reaction using 198-, 295- and 392-MeV proton beams to search for a direct evidence on an effect of the tensor interactions in light nucleus. Differential cross sections of the one-neutron transfer reaction populating the ground states and several low-lying excited states in 15O were measured. Comparing the ratios of the cross sections for each excited state to the one for the ground state over a wide range of momentum transfer, we found a marked enhancement of the ratio for the positive-parity state(s). The observation is consistent with large components of high-momentum neutrons in the initial ground-state configurations due to the tensor interactions. [Copyright &y& Elsevier]

The reduced transition probability B(E2;0+gs → 2+1) for 28S was obtained experimentally using Coulomb excitation at 53 MeV/nucleon. The resultant B(E2) value 181(31) e2frn4 is smaller than the expectation based on empirical B(E2) systematics. The double ratio |Mn/Mp|/(N/Z) of the 0+gs → 2+1 transition in 28S was determined to be 1.9(2) by evaluating the Mn value from the known B(E2) value of the mirror nucleus 28Mg, showing the hindrance of proton collectivity relative to that of neutrons. These results indicate the emergence of the magic number Z = 16 in the |Tz| =2 nucleus 28S. [ABSTRACT FROM AUTHOR]

A benchmark experiment on 208Pb shows that polarized proton inelastic scattering at very forward angles including 00 is a powerful tool for high-resolution studies of electric dipole (El) and spin magnetic dipole (MI) modes in nuclei over a broad excitation energy range to test up-to-date nuclear models. The extracted El polarizability leads to a neutron skin thickness rSkin = 0. 156+0.025-0.021 fm in 208Pb derived within a mean-field model [Phys. Rev. C 81, 051303 (2010)], thereby constraining the symmetry energy and its density dependence relevant to the description of neutron stars. [ABSTRACT FROM AUTHOR]

The vector analyzing power has been measured for the elastic scattering of neutron-rich 6He from polarized protons at 71 MeV/nucleon making use of a newly constructed solid polarized proton target operated in a low magnetic field and at high temperature. Two approaches based on local one-body potentials were applied to investigate the spin-orbit interaction between a proton and a 6He nucleus. An optical model analysis revealed that the spin-orbit potential for 6He is characterized by a shallow and long-ranged shape compared with the global systematics of stable nuclei. A semimicroscopic analysis with an α+n+n cluster folding model suggests that the interaction between a proton and the α core is essentially important in describing the p+6He elastic scattering. The data are also compared with fully microscopic analyses using nonlocal optical potentials based on nucleon-nucleon g matrices. [ABSTRACT FROM AUTHOR]

Abstract: We describe the neutron polarimeter NPOL3 for the measurement of polarization transfer observables with a typical high resolution of 300keV at . The NPOL3 system consists of three planes of neutron detectors. The first two planes for neutron polarization analysis are made of 20 sets of one-dimensional position-sensitive plastic scintillation counters with a size of 100cm 10cm 5cm, and they cover the area of . The last plane for detecting doubly scattered neutrons or recoiled protons is made of the two-dimensional position-sensitive liquid scintillation counter with a size of . The effective analyzing powers and double scattering efficiencies were measured by using the three kinds of polarized neutrons from the , , and reactions at . The performance of NPOL3 defined as are similar to that of the Indiana Neutron POLarimeter by taking into account for the counter configuration difference between these two neutron polarimeters. [Copyright &y& Elsevier]

A candidate resonant tetraneutron state is found in the missing-mass spectrum obtained in the double-charge-exchange reaction He4(He8,Be8) at 186 MeV/u. The energy of the state is 0.83±0.65(stat)±1.25(syst) MeV above the threshold of four-neutron decay with a significance level of 4.9σ. Utilizing the large positive Q value of the (8He,8Be) reaction, an almost recoilless condition of the four-neutron system was achieved so as to obtain a weakly interacting four-neutron system efficiently. [ABSTRACT FROM AUTHOR]