Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 49 (2016)

Spin-dipole response of 4 He
by exothermic charge exchange (8 He,8 Li∗ (1+ ))H. Miya,∗1 S. Shimoura,∗1 K. Kisamori,∗1,∗2 M. Assié,∗3 H. Baba,∗2 T. Baba,∗4 D. Beaumel,∗3 M. Dozono,∗1T. Fujii,∗2 N. Fukuda,∗2 S. Go,∗1 F. Hammache,∗3 E. Ideguchi,∗5 N. Inabe,∗2 M. Itoh,∗6 D. Kameda,∗2S. Kawase,∗1 T. Kawabata,∗4 M. Kobayashi,∗1 Y. Kondo,∗7 T. Kubo,∗2 Y. Kubota,∗1,∗2 C. S. Lee,∗1,∗2Y. Maeda,∗8 H. Matsubara,∗9 S. Michimasa,∗1 K. Miki,∗5 T. Nishi,∗10 M. Kurata-Nishimura,∗2 S. Ota,∗1
H. Sakai,∗2 S. Sakaguchi,∗11 M. Sasano,∗2 H. Sato,∗2 Y. Shimizu,∗2 H. Suzuki,∗2 A. Stolz,∗12 M. Takaki,∗1
H. Takeda,∗2 S. Takeuchi,∗2 A. Tamii,∗5 H. Tokieda,∗1 M. Tsumura,∗4 T. Uesaka,∗2 K. Yako,∗1
Y. Yanagisawa,∗2 and R. Yokoyama∗1
The spin dipole (SD) (∆S = ∆L =1) is one of thespin-isospin responses. On a double-closed nucleus,
the SD excitation contribution is large because of thenucleon conﬁguration. 4 He is leghtest of the doubleclosed nucleus, and has a simple conﬁguration. It iseasy to understand the SD response. This is important for the study of supernova nucleosynthesis with
the neutrino-nucleus reaction1) .
We conducted the exothermic charge-exchange (CE)reaction 4 He(8 He, 8 Li∗ (1+ ))4 H. CE reactions are used
as a powerful probe to study the spin-isospin responses.
The exothermic reaction enables targets to excite at
low momentum transfer due to the high reaction Qvalue. The kinematics of this reaction are closed ofthe neutrino-nucleus reaction, in contrast to the casein previous experiments. In this article, the angular
distribution of the reaction is reported.
The reaction was measured with the BigRIPS3) , thehigh-Resolution beamline4) , and the SHARAQ spectrometer5) at RIKEN RIBF. The liquid-4 He6) was installed at the target position of the SHARAQ. The
secondary 8 He beam irradiated the target at an intensity of about 2 MHz. In order to determine the missing mass energy and scattering angle, the trajectoryand momenta of 8 He and 8 Li were measured by using LP-MWDCs7) and CRDCs8) in the beamline andSHARAQ. The detail experimental setup is discribedin another report9) .
Figure 1 shows the cross section angular distribution obtained from the (8 He,8 Li∗ (1+ )). The verticaland horizontal axes are the diﬀerential cross section
and scattering angle in the center-of-mass frame, respectively. The closed circles were reduced from theexperimental data. The cross sections were summed

102Exp. Data
∆L=0:1+- - ∆L=1:0 ,1 ,2+ +∆L=2:1 ,2∆L=3:210dσ/dΩ (mb/sr)

110-110-210-310-410-501234 5 6 7θCM (degree)

8910Fig. 1. Cross section angular distribution obtained fromthe (8 He,8 Li∗ (1+ )) reaction. Closed circles donate theexperimental data. The lines show the DWBA calculation on the angular momentum transfer of ∆L =0, 1, 2, 3.

over the excitation energy in the range from 0 MeV
to 30 MeV for the continuum state of 4 H. The experimental data were compared with the DWBA calculation with FOLD10) . The lines show the calculated
cross sections on the angular momentum transfer of∆L = 0, 1, 2, 3. The experimental data qualitativelyindicated SD transition.
Comparison between the experimental data and thetheoretical calculation of the isovector type SD response of 4 He is now in progress.
References
1) T. Suzuki et al., Phys. Rev. C 74, 034307 (2006).
2) W. G. Love, M. A. Franey, Phys. Rev. C 24, 1073
(1981).
3) T. Kubo et al., Nucl. Instr. Meth. B 204, 97-113 (2003).
4) T. Kawabata et al., Nucl. Instr. Meth. B 266, 42014204 (2008).
5) S. Michimasa et al., Nucl. Instr. Meth. B 317, 305-310(2013).
6) H. Ryuto et al, Nucl. Instr. Meth. A555, 1-5 (2005).
7) H. Miya et al., Nucl. Instr. Meth. B 317, 701-704 (2013).
8) K. Kisamori et al., CNS Ann. Rep. 2011 (2013).
9) H. Miya et al., RIKEN Prog. Rep. 46 25 (2013).
10) J. Cook et al., ’Computer code FOLD/DWHI’, Frorida
State University (1988).

∗1Center for Nuclear Study, The University of Tokyo
RIKEN Nishina Center∗3 Institut de Physique Nucléaire, Orsay∗4 Department of Physics, Kyoto University∗5 Research Center Nuclear Physics, Osaka University∗6 Cyclotron and Radioisotope Center, Tohoku University∗7 Department of physics, Tokyo Institute of Technology∗8 Department of Applied Physics, University of Miyazaki∗9 National Institute of Radiological Sciences∗10 Department of physics, The University of Tokyo∗11 Department of Physics, Kyushu University∗12 National Superconducting Cyclotron Laboratory, Michigan
State University∗2- 53 -