RIKEN Accel. Prog. Rep. 50 (2017)

Ⅳ. OPERATION RECORDS

Operation report on the ring cyclotrons in the RIBF accelerator complex
K. Yadomi,*3 K. Suda,*1 T. Dantsuka,*1 M. Fujimaki,*1 T. Fujinawa,*1 N. Fukunishi,*1 S. Fukuzawa,*3M. Hamanaka,*3 H. Hasebe,*1 Y. Higurashi,*1 E. Ikezawa,*1 H. Imao,*1 S. Ishikawa,*3 O. Kamigaito,*1M. Kase,*1 M. Kidera,*1 K. Kobayashi,*3 M. Komiyama,*1 Y. Kotaka,*2 R. Koyama,*3 K. Kumagai,*1 T. Maie,*1M. Nagase,*1 T. Nagatomo,*1 T. Nakagawa,*1 M. Nakamura,*1 T. Nakamura,*3 M. Nishida,*3 M. Nishimura,*3J. Ohnishi,*1 H. Okuno,*1 K. Ozeki,*1 N. Sakamoto,*1 J. Shibata,*3 N. Tsukiori,*3 A. Uchiyama,*1 S. Watanabe,*1T. Watanabe,*1 Y. Watanabe,*1 K. Yamada,*1 and H. Yamasawa*1Table 1. Summary of the accelerated beams in 2016

In this report, the operation of the ring cyclotrons in theRIBF from January to December 2016 is presented. Table 1presents a summary of the beams accelerated by thesecyclotrons (the upper part until 238U at 10.75 MeV/u is forthe old facility, and the lower part from 18O at 230 MeV/u
for the new facility). The availability in the table is definedby the ratio of actual beam time to scheduled beam time,
which is an index of the reliability. The total beam supply
time in 2016 was 3724.2 h. In the old facility, the actual
beam time was 1025.4 h, and the availability was 107.4 %.
In the new facility, the total beam supply time was 2580.0 h,
and the availability was 91.2%.
For the experiments at the old facility, 22Ne, 58Ni, 48Ca and85
Rb for RIPS group, 40Ar and 84Kr for the industrial use(E5A), 86Kr for JAXA group (E3A), and 136Xe and 238U forKEK/KISS group (E2B) were supplied. In addition,biological experiments (E5B) were conducted as usual.
The 18O (230 MeV/u) beam was supplied to two
experiments (Jun. 16th to 30th). The maximum intensity
was 838 particle nA achieved by using the ion source
SCECR.1) The intensity was two times that in the previousoperation (March 2012)2). The availability was 99.0%
including the extension time of 15 h. The major troubles
were caused by radiation: the failures of EIC / EDC and themain power supply for RRC, and a malfunction of thefilament power supply for SRC-RES1.
The 48Ca beam was supplied to six experiments (Nov. 15thto Dec. 6th). The maximum intensity was 738 particle nA.
The availability was 96.5 % and the down time was 29.4 h.
Most of the down time was due to the replacement of thecharge stripper foils.
The 124Xe beam was supplied to one experiment (Apr. 28thto May 6th). The maximum intensity was 102 particle nA.
Owing to the improvement in transmission efficiencies, theintensity was increased by a factor of 2.7 compared withthat in the previous experiment of June 2013. Since thetuning time was shortened, the beam was supplied for aduration 12 h longer than scheduled. Consequently, theavailability became 105%.
The 238U beam was supplied for three periods as follows:
1) Apr. 6th to Apr. 22nd for two experiments, 2) May 16thto Jun. 13th for five experiments, and 3) Oct. 17th to Nov.
12th for four experiments. The maximum beam intensity
was 41 particle nA. The beam was supplied for 1370.1 h intotal, and the availability was 86.5%. The reason that theavailability became relatively low was that it took time todeal with several failures which frequently occurred. The
major troubles were 1) the failure of output capacitors of theamplifier for RRC RF No. 1, 2) an interlock system of SRC
He-refrigerator, 3) the power feeder of the S6 rebuncher,and 4) damages of the power feeder lines and directional
couplers caused by a high-power operation of theacceleration resonators for SRC.
References
1) T. Nakagawa et al.: RSI 75, 1394 (2004).

*1

RIKEN Nishina Center*2
Center for Nuclear Study, the University of Tokyo*3
SHI Accelerator Service Ltd.

2) M. Kase et al.: Proc. PASJ9, WEPS004, p. 350.

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