Ⅱ-1. Nuclear Physics
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Observation of 9 Li + d decay channel in 11 Li(p, n) reaction
L. Stuhl,∗1,∗2,∗3 M. Sasano,∗3 J. Gao,∗3,∗4 Y. Hirai,∗5 K. Yako,∗2 T. Wakasa,∗5 D. S. Ahn,∗3 H. Baba,∗3A. I. Chilug,∗6,∗3 S. Franchoo,∗7 Y. Fujino,∗8 J. Gibelin,∗9 I. S. Hahn,∗1,∗10 Z. Halász,∗11 T. Harada,∗12,∗3M. N. Harakeh,∗13,∗14 D. Inomoto,∗5 T. Isobe,∗3 H. Kasahara,∗5 D. Kim,∗1,∗15 G. G. Kiss,∗11 T. Kobayashi,∗16,∗3Y. Kondo,∗17,∗3 Z. Korkulu,∗1,∗3 S. Koyama,∗18,∗3 Y. Kubota,∗3 A. Kurihara,∗17 H. N. Liu,∗19 M. Matsumoto,∗17S. Michimasa,∗2 H. Miki,∗17,∗3 M. Miwa,∗20 T. Motobayashi,∗3 T. Nakamura,∗17,∗3 M. Nishimura,∗3 H. Otsu,∗3V. Panin,∗3 S. Park,∗10 A. T. Saito,∗17,∗3 H. Sakai,∗3 H. Sato,∗3 T. Shimada,∗17 Y. Shimizu,∗3 S. Shimoura,∗2A. Spiridon,∗6 I. C. Stefanescu,∗6 X. Sun,∗3,∗4 Y. L. Sun,∗19 H. Suzuki,∗3 E. Takada,∗21 Y. Togano,∗8,∗3T. Tomai,∗17,∗3 L. Trache,∗6 D. Tudor,∗6,∗3 T. Uesaka,∗3 H. Yamada,∗17 M. Yasuda,∗17 K. Yoneda,∗3K. Yoshida,∗3 J. Zenihiro,∗3 and N. Zhang∗22,∗2observation of these diﬀerent decay channels was conﬁrmed. Among them, the most interesting decay modeis 9 Li + d. This channel is related to the possibility thatin halo nuclei, the core and halo particles could decay,
more or less independently, into diﬀerent channels.9)
We observed a strong transition at approximately
19 MeV in the excitation energy spectrum of 11 Be. The
angular distribution in center-of-mass angle of the observed state indicates a strong forward peaking nature,
which suggests the GT transition, as depicted in Fig. 1,in agreement with previous β-decay studies.
CM (deg.)In the SAMURAI30 experiment, we studied theGamow-Teller (GT) giant resonance in the drip-line nucleus 11 Li at 181 MeV/nucleon utilizing the missingmass technique.1) The 11 Li nucleus is the showcase of a
two-neutron halo system, with its very extended matter distribution related to the small energy necessary toremove the neutrons. The charge-exchange (p, n) reactions in inverse kinematics are eﬃcient tools to extract
the B(GT) strengths of unstable isotopes up to highexcitation energies without the Q-value limitation.2) In
our previous study, we demonstrated that accurate information about isovector spin-ﬂip giant resonances canbe obtained for unstable nuclei using this probe.3) The
setup of the PANDORA low-energy neutron time-ofﬂight counter4) and SAMURAI magnetic spectrometer5) as well as a thick liquid hydrogen target, facilitate
the performance of measurements with high luminosity.
The β decay of 11 Li is complex. The large massdiﬀerence between 11 Li and its daughter 11 Be (Q =20.6 MeV) implies that several decay channels to thebound and unbound states in 11 Be are open. In thelatter cases, the daughter breaks into fragments, andthe emission of one, two, and three neutrons, α particles and 6 He, tritons, and deuterons has been observedin several β-decay studies.6,7) In our previous reports8)
on the preliminary results on GT giant resonance, theEx (11Be) (MeV)∗1

Center for Exotic Nuclear Studies, Institute for Basic Science∗2 Center for Nuclear Study, University of Tokyo∗3 RIKEN Nishina Center∗4 School of Physics, Peking University∗5 Department of Physics, Kyushu University∗6 Horia Hulubei National Institute for R&D in Physics andNuclear Engineering∗7 Institute de Physique Nucléaire, University Paris-Saclay∗8 Department of Physics, Rikkyo University∗9 Nuclear Physics Labratory LPC CAEN
∗10 Department of Physics, Ewha Womans University∗11 Institute for Nuclear Research (ATOMKI)∗12 Department of Physics, Toho University∗13 Department of Physics, University of Groningen∗14 GSI Helmholtzzentrum für Schwerionenforschung∗15 Department of Physics, Korea University∗16 Department of Physics, Tohoku University∗17 Department of Physics, Tokyo Institute of Technology∗18 Department of Physics, University of Tokyo∗19 Départment Physique Nucl., CEA, University Paris-Saclay∗20 Department of Physics, Saitama University∗21 National Institute of Radiological Sciences (NIRS)∗22 Institute of Modern Physics, Chinese Academy of Sciences- 25 -Fig. 1. Angular distribution, in the 0◦ –25◦ center-of-massangular range, of the strong peak observed in the excitation energy spectrum of the daughter nucleus 11 Be forthe 9 Li + d decay mode.

References
1) M. Sasano et al., Phys. Rev. Lett. 107, 202501 (2011).
2) T. N. Taddeucci et al., Nucl. Phys. A 469, 125 (1987).
3) J. Yasuda et al., Phys. Rev. Lett. 121, 132501 (2018).
4) L. Stuhl et al., Nucl. Instrum. Methods Phys. Res. A
866, 164 (2017).
5) T. Kobayashi et al., Nucl. Instrum. Methods Phys. Res.
B 317, 294 (2013).
6) R. Raabe et al., Phys. Rev. Lett. 101, 212501 (2008).
7) I. Mukha et al., Nucl. Phys. A 616, 201 (1997).
8) L. Stuhl et al., RIKEN Accel. Prog. Rep. 53, 38 (2019).
9) T. Nilsson et al., Hyperﬁne Interact. 129, 67 (2000).