II-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 54 (2021)

RIKEN Accel. Prog. Rep. 54 (2021)

Insight into the reaction dynamics of proton drip-line nuclear system
17
F + 58 Ni at near-barrier energies†
L. Yang,∗1 C. J. Lin,∗1,∗16 H. Yamaguchi,∗2,∗3 J. Lei,∗4 P. W. Wen,∗1 M. Mazzocco,∗5,∗6 N. R. Ma,∗1 L. J. Sun,∗1D. X. Wang,∗1 G. X. Zhang,∗7 K. Abe,∗2 S. M. Cha,∗8 K. Y. Chae,∗8 A. Diaz-Torres,∗9 J. L. Ferreira,∗10S. Hayakawa,∗2 H. M. Jia,∗1 D. Kahl,∗1 A. Kim,∗11 M. S. Kwag,∗8 M. La Commara,∗12 R. Navarro Pérez,∗13C. Parascandolo,∗14 D. Pierroutsakou,∗14 J. Rangel,∗10 Y. Sakaguchi,∗2 C. Signorini,∗5,∗6 E. Strano,∗5,∗6
X. X. Xu,∗1 F. Yang,∗1 Y. Y. Yang,∗15 G. L. Zhang,∗7 F. P. Zhong,∗1,∗16 and J. Lubian∗10
In recent times, the availability of high-quality radioactive beams has greatly increased our ability tostudy the reactions induced by exotic nuclei.1) In contrast to neutron-halo projectiles, reactions induced byweakly bound proton-rich nuclei, especially those with
proton-halo or valence-proton structures, present distinctive properties. Both the core and valence proton
have long-range Coulomb interaction with the target;
thus, the dynamic Coulomb polarization eﬀect is of particular importance.2) So far, research on reactions with
proton drip-line nuclei is still in its infancy, and the reaction mechanism is not yet clear.
17F can be treated properly with a two-body model
as an inert 16 O core and a loosely bound proton.3) In
this report, we present the results of complete kinematics measurements to investigate the reaction mechanisms of 17 F interacting with 58 Ni at energies around theCoulomb barrier. The experiment was performed at theCenter for Nuclear Study Radioactive Ion Beam separator (CRIB).4) The Multi-layer Ionization-chamber Telescope Array (MITA)5) was used to detect the reaction
products over a large range of Z. Angular distributionsof elastic scattering, exclusive and inclusive breakup, as
well as the total fusion (TF) cross sections were derived
simultaneously for the ﬁrst time.
The excitation functions of the total reaction (σR ),inclusive (σInc.16 O ) and exclusive (σExc.16 O ) 16 O, as wellas the TF from evaporation protons are shown in Fig. 1.
Fusion is dominant in the above-barrier region, andit reduces exponentially as the energy decreases. The
σInc.16 O and σExc.16 O , however, vary smoothly with
Condensed from the article in Phys. Lett. B 813, 136045(2021)∗1 Department of Nuclear Physics, China Institute of Atomic
Energy∗2 Center for Nuclear Study, University of Tokyo∗3 National Astronomical Observatory of Japan∗4 Institute of Nuclear and Particle Physics, and Department ofPhysics and Astronomy, Ohio University∗5 Dipartimento di Fisica, Universita di Padova∗6 Istituto Nazionale di Fisica Nucleare-Sezione di Padova∗7 School of Physics, Beihang University∗8 Department of Physics, Sungkyunkwan University∗9 Department of Physics, University of Surrey∗10 Instituto de Física, Universidade Federal Fluminense∗11 Department of Science Education, Ewha Womans University∗12 Department of Pharmacy, University Federico II∗13 Department of Physics, San Diego State University∗14 Istituto Nazionale di Fisica Nucleare-Sezione di Napoli∗15 Institute of Modern Physics, Chinese Academy of Sciences∗16 Department of Physics, Guangxi Normal University†the energy, and σInc.16 O becomes the major component in the sub-barrier region. The behavior of the TF
cross section can only be reproduced by the continuumdiscretized coupled-channels (CDCC) calculation considering the couplings from the continuum states, indicating that the enhancement of TF at the sub-barrierenergy is mainly due to the breakup coupling.

Fig. 1. Excitation functions of the total reaction (stars), exclusive (squares) and inclusive (triangles) breakups, andthe TF (circles). The curves denote the corresponding theoretical results: the solid line denotes the coupled channel (CC) result; the dot-dot-dashed and dottedcurves are the CDCC results for TF and elastic breakup,respectively; the dashed line shows the CDCC calculations performed by switching oﬀ the couplings from thecontinuum states (NCC); and the dot-dashed line is theresult of the three-body model proposed by Ichimura,Austern, and Vincent6) plus CDCC. The arrow indicatesthe nominal position of the Coulomb barrier.

References

1) L. F. Canto et al., Phys. Rep. 596, 1 (2015).
2) M. Ito, K. Yabana, T. Nakatsukasa, M. Ueda, Nucl. Phys.
A 787, 267c (2007).
3) C. A. Bertulani, P. Danielewicz, Nucl. Phys. A 717, 199(2003).
4) Y. Yanagisawa et al., Nucl. Instrum. Methods Phys. Res.
A 539, 74 (2005).
5) N. R. Ma et al., Eur. Phys. J. A 55, 87 (2019).
6) M. Ichimura et al., Phys. Rev. C 32, 431 (1985).

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