Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 51 (2018)

Commissioning of the OEDO beamline
S. Michimasa,∗1 S. Shimoura,∗1 K. Yamada,∗2 S. Ota,∗1 M. Dozono,∗1 N. Imai,∗1 J. W. Hwang,∗1M. Matsushita,∗1 K. Yoshida,∗2 Y. Yanagisawa,∗2 K. Kusaka,∗2 M. Ohtake,∗2 D. S. Ahn,∗2 O. Beliuskina,∗1N. Chiga,∗2 K. Chikaato,∗3 N. Fukuda,∗2 S. Hayakawa,∗1 E. Ideguchi,∗4 K. Iribe,∗5 C. Iwamoto,∗1 S. Kawase,∗6K. Kawata,∗1 N. Kitamura,∗1 S. Masuoka,∗1 H. Miyatake,∗7 D. Nagae,∗2 S. Naimi,∗2 R. Nakajima,∗1T. Nakamura,∗8 K. Nakano,∗6 M. Nakano,∗9 S. Ohmika,∗2 H. Otsu,∗2 H. Sakurai,∗2,∗10 S. Sato,∗9 P. Schrock,∗1H. Shimizu,∗1 Y. Shimizu,∗2 T. Sumikama,∗2 X. Sun,∗2 D. Suzuki,∗2 H. Suzuki,∗2 M. Takaki,∗1 M. Takechi,∗3H. Takeda,∗2 S. Takeuchi,∗8 T. Teranishi,∗5 R. Tsunoda,∗1 H. Wang,∗2 Y. Watanabe,∗6 Y. X. Watanabe,∗7K. Wimmer,∗10,∗2 K. Yako,∗1 H. Yamaguchi,∗1 L. Yang,∗1 and H. Yoshida∗5The OEDO system was proposed to produce focusedslow-down radioactive-ion (RI) beams in RIBF1) andhas been installed in the High-Resolution Beamline(HRB) in the end of ﬁscal year 2016.2) The commissioning of the OEDO beamline has been performed inJune 15–21, 2017.
A schematic view of the OEDO beamline and detector setup is shown in Fig. 1. The main componentsof the OEDO system are a radio-frequency deﬂector(RFD) synchronized with the cyclotron’s RF and 2 setsof superconducting triplet quadrupole (STQ) magnets.
For matching to the ion optics of the OEDO system,
the momentum dispersion from the BigRIPS to FE9
was tuned to be 13 mm/% at FE9. An Al degraderat FE9 slows down RIs to less than 50 MeV/nucleon.
The inset of Fig. 1 shows calculated ion trajectories ofthe OEDO system on the horizontal plane. The ﬁrst
STQ in the ﬁgure provides point-to-parallel transport,
resulting in a strong correlation between the angularand time components of the beam. The second STQ
works as inverse transformation of the ﬁrst one. The
RFD periodically changes the RI’s horizontal angles inorder to align them in parallel. The aligned RIs focusat FE11 through the central trajectory in the second
half of the OEDO system.
In the commissioning run, long-lived ﬁssion prod-ucts 79 Se and 107 Pd were produced from a 345MeV/nucleon 238 U beam. The beam energy of 79 Se(107 Pd) was tuned to be 170 (180) MeV/nucleon in
BigRIPS and 45 ± 2 (33 ± 0.5) MeV/nucleon at FE11
after energy reduction by degraders and detectors.
Figure 2 displays correlations between the arrival
timing at FE10 and the horizontal hit position atFE11, where Figs. 2(a) and (b) show those without andwith RFD operation, respectively. The ﬁgures demonstrate that the RFD focuses the 79 Se beam and canadjust the beam position. The FE11 horizontal beam
spot size was reduced from 25 mm to 15 mm in FWHM,
as shown in Fig. 3.

Fig. 2. Ion-optical eﬀect of RFD for beam focusing.

Fig. 3. Beam focusing of 79 Se at FE11 with and without
RFD.

Fig. 1. Schematic view of the OEDO beamline. The ionoptics in the OEDO system are also shown.
∗1Center for Nuclear Study, the University of Tokyo
RIKEN Nishina Center∗3 Dept. of Physics, Niigata University∗4 RCNP, Osaka University∗5 Dept. of Physics, Kyushu University∗6 Dept. of Advanced Energy Eng. Sci., Kyushu University∗7 Wako Nuclear Science Center, KEK∗8 Dept. of Physics, Tokyo Institute Technology∗9 Dept. of Physics, Rikkyo University∗10 Dept. of Physics, The University of Tokyo∗2The OEDO beamline was successfully launched.
Further data analysis is ongoing to improve the transmission of the beamline and to develop an eﬀective
tuning procedure for upcoming physics experiments.
This work was funded by ImPACT Program ofCouncil for Science, Technology and Innovation (Cabinet Oﬃce, Government of Japan).
References
1) S. Shimoura et al., CNS-REP-93, 56 (2015).
2) S. Michimasa et al., RIKEN Accel. Prog. Rep. 50, 19(2017).

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