RIKEN Accel. Prog. Rep. 48 (2015)

Ⅱ-1. Nuclear Physics

Study of nuclear structure in proton-rich carbon isotopes
T. Miyazaki,∗1,∗2 H. Otsu,∗2 E. Yu. Nikolskii,∗2,∗5 Y. Shiga,∗2,∗3 M. Kurata-Nishimura,∗2 S. Takeuchi,∗2Y. Satou,∗4 M. Kurokawa,∗2 H. Baba,∗2 G. Lorusso,∗2 T. Isobe,∗2 M. Niikura,∗1 E. A. Kuzmin,∗2,∗5
A. A. Korsheninnikov,∗2,∗5 A. A. Ogloblin,∗2,∗5 S. A. Krupko,∗6 M. S. Golovkov,∗6 A. A. Bezbakh,∗6
R. S. Slepnev,∗6 A. S. Fomichev,∗6 S. I. Sidorchuk,∗6 A. V. Gorshkov,∗6 A. G. Knyazev,∗6 P. Papka,∗7H. J. Ong,∗8 S. Kim,∗4 J. W. Hwang,∗4 S. Choi,∗4 H. Chae,∗4 E. Kim,∗4 Y. H. Kim,∗4 D. Lubos,∗2,∗9D. Beaumel,∗2,∗10 P. A. Söderström,∗2 S. Sakaguchi,∗11 S. Kubono,∗2 A. K. Perrevoort,∗2 E. Milman,∗2S. Chebotaryov,∗2 W. Powell,∗2 T. Motobayashi,∗2 K. Yoneda,∗2 and H. Sakurai∗1,∗2∗1

Department of Physics, The University of Tokyo
RIKEN Nishina Center∗3 Department of Physics, Rikkyo University∗4 Department of Physics, Seoul National University∗5 National Research Centre “Kurchatov Institute”∗6 Flerov Laboratory of Nuclear Reactions, Joint Institute forNuclear Research∗7 Department of Physics, Stellenbosch University∗8 Research Center for Nuclear Physics, Osaka University∗9 Technische Universität München∗10 Institut de Physique Nucléaire d’Orsay, IN2P3/CNRS∗11 Department of Physics, Kyushu University∗2ing the 10 C(p, t) and 10 C(p, d) reactions, respectively.
Their excitation energies were consistent with the previous results. In future studies, observation of the excited states in 8 C with higher statistics, better energyresolution, and higher S/N ratio is expected.

Counts/ 250
keV


400

400


g.s.


300

300


200

200


100

100

00-10

-10
-5-500

55


10
10
1515

x[MeV] EFig. 1. The excitation energy spectrum of 8 C.

500

500



Counts/ 250
keV

The structures of the proton-rich carbon isotopes 8 C
and 9 C were studied by the neutron transfer 10 C(p, t)
and 10 C(p, d) reactions, respectively. The experiment
was aimed at measuring the unknown excited statesin 8 C, which had not been achieved in the previousstudies1–4) and identifying the decay property of theunbound ﬁrst excited state in 9 C.
The experiment was performed in 2013 at theRIKEN RIPS facility5) . A 10 C secondary beam at51 AMeV was impinged on the hydrogen gas target system (CRYPTA)6,7) . Recoilied tritons and deuterons
were identiﬁed by using the ∆E-E method, with thehelp of the Dubna telescope consisting of an annular
double-sided strip silicon detector and 16 CsI(Tl) scintillators. The reaction residues were identiﬁed by the∆E-E method using a four-plastic-scintillator array at0 degree8) .
The excitation energy spectrum of 8 C after subtracting the background is shown in Fig. 1. The groundstate of 8 C was observed. The deduced mass excess of
the 8 C nucleus was 34.9(1.1) MeV, which is consistent
with the values reported in previous works1–4) . The
diﬀerential cross-section of the 10 C(p, t)8 Cg.s. reaction
will be analyzed in order to deduce the transferred angular momentum in the reaction.
The background-subtracted excitation energy spectrum of 9 C is shown in Fig. 2. The known groundand ﬁrst excited states in 9 C were observed. The deduced excitation energy of the ﬁrst excited state in 9 C
was 2.4(5) MeV, which is consistent with the value obtained in the previous experiment9) . By tagging theresidual nucleus separated by the detectors at 0 degree, the decay paths of the ﬁrst excited states in 9 C
will be determined.
In summary, the ground state of 8 C and the groundand ﬁrst excited states of 9 C were observed by us-400

400


g.s.

2.2


300300
200200
100100-500-500Ex[MeV] 551010Fig. 2. The excitation energy spectrum of 9 C.

References
1) R. G. H. Robertson et al.: Phys. Rev. Lett. 32, 1207 (1974).
2) R. E. Tribble et al.: Phys. Rev. C 13, 50 (1976).
3) R. G. H. Robertson et al.: Phys. Rev. C 13, 1018 (1976).
4) R. J. Charity et al.: Phys. Rev. C 84, 014320 (2011).
5) T. Kubo et al.: Nucl. Instrum. Methods B 70, 309 (1992).
6) H. Ryuto et al.: Nucl. Instrum. Methods. A 555, 1 (2005).
7) M. Kurata-Nishimura et al.: RIKEN Accel. Prog. Rep. 46,165 (2013).

8) T. Miyazaki et al.: RIKEN Accel. Prog. Rep. 47, 23 (2014).
9) W. Benenson and E. Kashy: Phys. Rev. C 10, 2633 (1974).

- 62 -完全版2014_本文.indd 62

15/10/16 17:42