References - Bogoliubov Laboratory of Theoretical Physics - JINR

SPIN-ORBIT POTENTIALS IN NEUTRON-RICH HELIUM ISOTOPES
S. Sakaguchi 1,† ,T.Uesaka 2 T. Kawabata 2 T. Wakui 3 ,N.Aoi 1 ,Y.Hashimoto 4 ,
M. Ichikawa 5 ,Y.Ichikawa 6 ,K.Itoh 7 ,M.Itoh 3 ,H.Iwasaki 6 , T. Kawahara 8 ,
Y. Kondo 7 ,H.Kuboki 6 ,Y.Maeda, 9 ,R.Matsuo 5 ,T.Nakamura 7 ,T.Nakao 6 ,
Y. Nakayama 7 ,S.Noji 4 ,H.Okamura 10 , H. Sakai 6 , N. Sakamoto 1 , Y. Sasamoto 2
M. Sasano 6 ,Y.Satou 4 , K. Sekiguchi 1 ,T.Shimamura 7 , Y. Shimizu 2 M. Shinohara 4 ,
K. Suda, 1 , D. Suzuki 6 , Y. Takahashi 6 ,A.Tamii 10 ,K.Yako 6 and M. Yamaguchi 1
(1) RIKEN (The Institute of Physical and Chemical Research), Japan
(2) Center for Nuclear Study, Graduate School of Science, University of Tokyo, Japan
(3) Cyclotron and Radioisotope Center, Tohoku University, Japan
(4) Department of Physics, Tokyo Institute of Technology, Japan
(5) Department of Physics, Tohoku University, Japan
(6) Department of Physics, University of Tokyo, Japan
(7) Department of Physics, Saitama University, Japan
(8) Department of Physics, Toho University, Japan
(9) Department of Physics, Kyushu University, Japan
(10) Research Center for Nuclear Physics, Osaka University, Japan
† E-mail: satoshi@ribf.riken.jp
Abstract
We measured the vector analyzing power of the proton elastic scattering from
neutron-rich helium isotopes 6 He and 8 He at 71 MeV/u. A solid polarized proton
target specially constructed for radioactive-ion beam experiments was successfully
applied. Deduced spin-orbit potentials between protons and 6,8 He are found to be
remarkably shallow. Dominance of the interaction between a proton and an α core
in 6,8 He is also indicated.
1 Introduction
Recently, renewed interest has been focused on the spin-dependent interaction in unstable
nuclei. One of the most direct methods to extract the information on the spin-dependent
interaction is the scattering experiment induced by spin-polarized light ions. In order
to investigate the unstable nuclei with spin polarization, a polarized proton solid target,
which was specially designed for radioactive-ion beam experiments, has been developed
at CNS [1, 2]. The most prominent advantage of this target is in its modest operation
condition, i.e., a low magnetic field of 0.1 T and a high temperature of 100 K. This
condition allows us to detect low energy recoiled protons, which are essential for event
selection. Making use of this target, we measured the vector analyzing power of the
proton elastic scattering from 6 He and 8 He at 71 MeV/A in 2005 and 2007. The aim of
the measurements is to extract the feature of the shape of spin-orbit potentials between
protons and 6,8 He, and discuss the effect of valence neutrons on the spin-orbit potential
from the systematics between isotopes. Details of the measurement and the optical model
analysis are reported.
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