Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 49 (2016)

Study of Gamow-Teller transition from 132 Sn via the (p, n) reaction
in inverse kinematics
J. Yasuda,∗1,∗2 M. Sasano,∗1 R.G.T. Zegers,∗3 H. Baba,∗1 D. Bazin,∗3 W. Chao ,∗1 M. Dozono,∗1 N. Fukuda,∗1N. Inabe,∗1 T. Isobe,∗1 G. Jhang,∗1,∗4 D. Kameda,∗1 M. Kaneko, ∗5 S. Kawase,∗6 K. Kisamori,∗1,∗6M. Kobayashi,∗6 N. Kobayashi, ∗7 T. Kobayashi,∗1,∗8 S. Koyama,∗1,∗7 Y. Kondo,∗1,∗9 A. Krasznahorkay,∗10T. Kubo,∗1 Y. Kubota,∗1,∗6 M. Kurata-Nishimura,∗1 C.S. Lee,∗1,∗6 J.W. Lee, ∗4 Y. Matsuda, ∗11E. Milman,∗1,∗12 S. Michimasa,∗6 T. Motobayashi,∗1 D. Mucher, ∗1,∗13 T. Murakami, ∗5 T. Nakamura,∗1,∗9N. Nakatsuka, ∗1,∗5 S. Ota,∗6 H. Otsu,∗1 V. Panin, ∗1 W. Powell, ∗1 S. Reichert, ∗1,∗13 S. Sakaguchi,∗1,∗2H. Sakai,∗1 M. Sako, ∗1 H. Sato,∗1 Y. Shimizu,∗1 M. Shikata,∗1,∗9 S. Shimoura,∗6 L. Stuhl,∗1 T. Sumikama,∗1,∗8H. Suzuki,∗1 S. Tangwancharoen, ∗1 M. Takaki,∗6 H. Takeda,∗1 T. Tako,∗8 Y. Togano,∗1,∗9 H. Tokieda,∗6J. Tsubota,∗1,∗9 T. Uesaka,∗1 T. Wakasa,∗2 K. Yako,∗6 K. Yoneda,∗1 and J. Zenihiro∗1cited states in 132 Sb. Clear kinematic loci are also visible in Figs. 1(b), 1(c), and 1(d) and shifted to higher
excitation energies including the GTGR according tothe decay threshold. It means that the γ, 1n, 2n, and3n decay channels are successfully measured. The dataanalysis for obtaining GT distribution is in progress.

We performed measurements on the 132 Sn(p, n) reaction at 220 MeV/nucleon in inverse kinematics at
RIBF in order to extract Gamow-Teller (GT) transitions from the key doubly magic nucleus 132 Sn. Thisis an essential step toward establishing comprehensive
theoretical models for nuclei situated between 78 Ni and208Pb.
The experiment was carried out by using theWide-angle Inverse-kinematics Neutron Detectors for
SHARAQ (WINDS)1) and the large acceptance
SAMURAI spectrometer2) . A secondary beam of132
Sn was transported onto a 10-mm thick liquid hydrogen target3) , which was surrounded by WINDS todetect recoil neutrons. From the measured neutron
time-of-ﬂight and recoil angle, the excitation energy
and center-of-mass scattering angle were determined.
The SAMURAI spectrometer was used for tagging(p, n) reaction events with particle identiﬁcation of theoutgoing heavy residues. Owing to the large momentum acceptance of SAMURAI, we can measure all theheavy residues with diﬀerent rigidities in one setting.
It allows us to reconstruct the excitation energy spectrum up to high excitation energies including the GT
giant resonance (GTGR).
Figure 1 shows scatter plots of neutron energy (En )versus laboratory scattering angle (θlab ) for neutrons
detected in WINDS, for events associated with the132
Sn beam component. Scatter plots are shown separately for diﬀerent heavy residues detected in the spectrometer. In Fig. 1(a), one can see a clear kinematical correlation between En and θlab , corresponding totransitions going to the ground state or low-lying ex-132

Sn(p, n)132 Sb∗ 220 MeV/nucleon

132

131

Sb in spectrometer

Sb in spectrometer
40Neutron Energy En (MeV)

10(b)

(a)

8200 Ex10◦8◦θcm 6◦64◦42◦20020130
10406080

1000(c)820129Sb in spectrometer

406080100Sb in spectrometer(d)6420020406080

100020406080

100

Scattering angle θlab (deg)Fig. 1. Neutron spectra as a function of neutron energy(En ) and scattering angle in the laboratory frame (θlab )for the 132 Sn beam component and for events associatedwith the heavy residues in the spectrometer: (a) 132 Sb,(b) 131 Sb, (c) 130 Sb, and (d) 129 Sb.

∗1RIKEN Nishina CenterDepartment of Physics, Kyushu University∗3 NSCL Michigan State University∗4 Department of Physics, Korea University∗5 Kyoto University∗6 CNS, University of Tokyo∗7 University of Tokyo∗8 Department of Physics, Tohoku University∗9 Tokyo Institute of Technology∗10 MTA, Atomki∗11 Konan University∗12 Department of Physics, Kyungpook National University∗13 Technical University Munich∗2References
1) K. Yako et al., RIKEN Accel. Prog. Rep. 45 137 (2012).
2) T. Kobayashi et al., Nucl. Instr. Meth. B 317, 294(2013).
3) M. Kurata-Nishimura et al., RIKEN Accel. Prog. Rep45, 122 (2012).

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