M. Shinohara

Analyzing power in elastic scattering of 6He from a polarized proton target at 71 MeV/nucleon

The vector analyzing power has been measured for the elastic scattering of neutron-rich {sup 6}He 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 {sup 6}He nucleus. An optical model analysis revealed that the spin-orbit potential for {sup 6}He is characterized by a shallow and long-ranged shape compared with the global systematics of stable nuclei. A semimicroscopic analysis with an {alpha}+n+n cluster folding model suggests that the interaction between a proton and the {alpha} core is essentially important in describing the p+{sup 6}He elastic scattering. The data are also compared with fully microscopic analyses using nonlocal optical potentials based on nucleon-nucleon g matrices.

Unbound excited states in 19,17C

The neutron-rich carbon isotopes 19,17C have been investigated via proton inelastic scattering on a liquid hydrogen target at 70 MeV/nucleon. The invariant mass method in inverse kinematics was employed to reconstruct the energy spectrum, in which fast neutrons and charged fragments were detected in coincidence using a neutron hodoscope and a dipole magnet system. A peak has been observed with an excitation energy of 1.46(10) MeV in C, while three peaks with energies of 2.20(3), 3.05(3), and 6.13(9) MeV have been observed in C. Deduced cross sections are compared with microscopic DWBA calculations based on p-sd shell model wave functions and modern nucleon-nucleus optical potentials. Jπ assignments are made for the four observed states as well as the ground states of both nuclei.

Analyzing power for proton elastic scattering from the neutron-rich He6 nucleus

Vector analyzing power for the proton-{sup 6}He elastic scattering at 71 MeV/nucleon has been measured for the first time, with a newly developed polarized proton solid target, which works at a low magnetic field of 0.09 T. The results are found to be incompatible with a t-matrix folding model prediction. Comparisons of the data with g-matrix folding analyses clearly show that the vector analyzing power is sensitive to the nuclear structure model used in the reaction analysis. The {alpha}-core distribution in {sup 6}He is suggested to be a possible key for understanding the nuclear structure sensitivity.

One-neutron knockout reaction of 17C on a hydrogen target at 70 MeV/nucleon

Abstract First experimental evidence of the population of the first 2 − state in 16 C above the neutron threshold is obtained by neutron knockout from 17 C on a hydrogen target. The invariant mass method combined with in-beam γ -ray detection is used to locate the state at 5.45(1) MeV. Comparison of its populating cross section and parallel momentum distribution with a Glauber model calculation utilizing the shell-model spectroscopic factor confirms the core-neutron removal nature of this state. Additionally, a previously known unbound state at 6.11 MeV and a new state at 6.28(2) MeV are observed. The position of the first 2 − state, which belongs to a member of the lowest-lying p – sd cross shell transition, is reasonably well described by the shell-model calculation using the WBT interaction.

14Be(p,n)14B reaction at 69 MeV in inverse kinematics

Y. Satou, ∗ T. Nakamura, Y. Kondo, N. Matsui, Y. Hashimoto, T. Nakabayashi, T. Okumura, M. Shinohara, N. Fukuda, T. Sugimoto, H. Otsu, Y. Togano, T. Motobayashi, H. Sakurai, Y. Yanagisawa, N. Aoi, S. Takeuchi, T. Gomi, M. Ishihara, S. Kawai, H.J. Ong, T.K. Onishi, S. Shimoura, M. Tamaki, T. Kobayashi, Y. Matsuda, N. Endo, and M. Kitayama Department of Physics and Astronomy, Seoul National University, 599 Gwanak, Seoul 151-742, Republic of Korea Department of Physics, Tokyo Institute of Technology, 2-12-1 Oh-Okayama, Meguro, Tokyo 152-8551, Japan RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan Department of Physics, Rikkyo University, 3 Nishi-Ikebukuro, Toshima, Tokyo 171-8501, Japan Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan Center for Nuclear Study (CNS), University of Tokyo, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan Department of Physics, Tohoku University, Aoba, Sendai, Miyagi 980-8578, Japan (Dated: January 12, 2013)

Elastic Scattering of Neutron-Rich Helium Isotopes from Polarized Protons at 71 MeV/A

The vector analyzing power has been measured for the elastic scattering of neutron-rich 6He and 8He from polarized protons at 71 MeV/A making use of a newly constructed solid polarized proton target operated in a low magnetic field of 0.1 T and at a relatively high temperature of 100 K. An optical model analysis revealed that the spin-orbit potentials for 6He and 8He are characterized by shallow and long-ranged shape compared with the global systematics of stable nuclei. Such a characteristics reflect a diffused density distribution of the neutron-rich isotopes.

Analyzing Power Measurement for Elastic Scattering of 6He on Polarized Protons

Vector analyzing power was measured for the proton elastic scattering on 6He at 71 MeV/u. We applied a solid polarized proton target, which was operated in a low magnetic field of 88 mT and at high temperature of 100 K, to a radioactive‐isotope beam experiment. Low energy recoil protons were successfully detected due to the modest operation conditions of the target. Selection of p+6He elastic scattering events was clearly carried out with detected protons. Absolute values of the analyzing power were determined for the first time.

(p, p′) and (p, n) reactions on halo nuclei

We have measured the 1H(19C,18C+n)1H and 1H(14Be,13B+n)n reactions at 70 MeV/nucleon using the invariant mass method in inverse kinematics. A new state was identified at 1.49 MeV in 19C. In the latter (p, n) reaction, a resonance peak corresponding to the 1.28 MeV state in 14B recently reported in a beta-decay study was clearly observed. Forward peaked character in the differential cross section supports the 1+assignment for this state.