Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 49 (2016)17F elastic scattering and total reaction cross section on 58 Ni target
around Coulomb barrier

C. J. Lin,∗1 L. Yang,∗1 N. R. Ma,∗1 H. M. Jia,∗1 H. Yamaguchi,∗2 M. Mazzocco,∗3∗4 L. J. Sun,∗1 D. X. Wang,∗1S. Hayakawa,∗2 D. Kahl,∗2 S. M. Cha,∗5 G. X. Zhang,∗6 F. Yang,∗1 Y. Y. Yang,∗7 C. Signorini,∗3∗4
Y. Sakaguchi,∗2 K. Abe,∗2 A. Kim,∗5 K. Y. Chae,∗5 M. S. Kwag,∗5 D. Pierroutsakou,∗4 C. Parascandolo,∗4M. La Commara,∗4∗8 E. Strano∗4∗93500

The reaction mechanisms of weakly bound nuclear
systems have attracted much attention lately1) . Because of the small binding energy, the weakly boundprojectiles can easily break up into smaller fragments
when they interact with the target2) . Moreover, theconsequence of the breakup channel on the fusion
process is still controversial3) . Therefore, a detailed
knowledge on the breakup process is important fora deep understanding of the reaction mechanism ofweakly bound systems.
In view of this fact, 17 F4) was chosen to study thebreakup mechanism of the 17 F+58 Ni system. For thispurpose, a new detector array has been designed, toperform a complete-kinematics measurement. The array consists of ten detector units, each of which contains one ion chamber (IC), followed by one double-sidesilicon detector (DSSD), and two thick quartered silicon detectors (QSDs). Based on this array, the energy
and angle correlations between the breakup fragments
can be measured to reconstruct the intermediate stateof the breakup process. The elastic scattering and other reaction channels can also be measured to investigate the total reaction cross-section. The resolution ofsingle detector unit is around 4%. Thus, the inelastic channel may not be distinguished. However, theinﬂuence can be estimated because there is only one
excited state below the breakup threshold of 17 F.
The experiment was performed at the CRIB (CNS Radio Isotope Beam) separator from Dec.10 to19, 2015. The radioactive 17 F was produced by the2H(16 O,17 F) reaction using a 6.6 MeV/u 16 O primary beam impinging on a H2 gas target. Four diﬀerent
17F secondary beam energies were obtained. The former, 59.7 MeV, was achieved with a gas pressure of254 torr and a Al degrader with a thickness of 5 µm.
By increasing the gas pressure and Al degrader up to262 torr and 12 µm, as well as 316 torr and 17 µm, thebeam energies of 49.7 MeV and 46 MeV were obtained,respectively. The latter, 65 MeV, was achieved with a
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∆E1 (channel)

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171000

16O

F

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ER1 (channel)

2000∆E2 (channel)

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p

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Fig. 1. Identiﬁcation of particles yielding from 17 F+58 Ni at
Elab (17 F)=59.7 MeV. Symbols ∆E1 and ER1 represent
the IC and DSSD, respectively, and ∆E2 and ER2 are
the two QSDs. The horizontal tail of 17 F arises fromthe radiation damage and/or channeling eﬀect of thesolid detector.

gas pressure of 250 torr and without a degrader. After
selection by the WF and tracked by two PPACs, thesecondary beam, with an intensity of 6-10×105 pps,
was then impinged on the secondary target, 58 Ni, witha thickness of 1 mg/cm2 . The identiﬁcation of particles obtained using the ﬁrst detector unit (θlab from15.2◦ to 30.5◦ ) is shown in Fig. 1. It can be seen that
17F, 16 O, and p can be distinguished clearly.
The data analysis is in progress now.
References

Department of Nuclear Physics, China Institute of Atomic
EnergyCenter for Nuclear Study, University of Tokyo
University of Padova
INFN
Department of Physics, Sungkyunkwan University
Department of Physics, Beihang University
Institute of Modern Physics, Chinese Academy of Sciences
University of Naples
University of Catania

1) N. Keeley, R. Raabe, N. Alamanos, and J. L. Sida:
Prog. Part. Nucl. Phys. 59, 579 (2007).
2) N. Keeley, N. Alamanos, K. W. Kemper and K. Rusek:
Prog. Part. Nucl. Phys. 63, 396 (2009).
3) J. F. Liang and C. Signorini: Int. J. Mod. Phys. E 14,1121 (2005).
4) M. Mazzocco, C. Signorini, D. Pierroutsakou et al.:Phys. Rev. C 82, 054604 (2010).

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