Ⅳ. OPERATION RECORDS

RIKEN Accel. Prog. Rep. 49 (2016)

Operationreportreportonon thethe ring-cyclotrons
ring-cyclotrons inOperationin thethe RIBF
RIBF accelerator
acceleratorcomplex
complex
M. Nishida,㸨3 K. Ozeki,㸨1 T. Dantsuka,㸨1 M. Fujimaki,㸨1 T. Fujinawa,㸨1 N. Fukunishi,㸨1 S. Fukuzawa,㸨3 M. Hamanaka,㸨3H. Hasebe,㸨1 Y. Higurashi,㸨1 E. Ikezawa,㸨1 H. Imao,㸨1 S. Ishikawa,㸨3 T. Kageyama,㸨1 O. Kamigaito,㸨1 M. Kase,㸨1M. Kidera,㸨1 K. Kobayashi,㸨3 M. Komiyama,㸨1 Y. Kotaka,㸨2 R. Koyama,㸨3 K. Kumagai,㸨1 T. Maie,㸨1 M. Nagase,㸨1T. Nagatomo,㸨1 T. Nakagawa,㸨1 M. Nakamura,㸨1 T. Nakamura,㸨3 M. Nishimura,㸨3 J. Ohnishi,㸨1 H. Okuno,㸨1N. Sakamoto,㸨1 J. Shibata,㸨3 K. Suda,㸨1 N. Tsukiori,㸨3 A. Uchiyama,㸨1 S. Watanabe,㸨1 T. Watanabe,㸨1 Y. Watanabe,㸨1K. Yadomi,㸨3 K. Yamada,㸨1 and H. Yamasawa㸨1In this report, the operation of the ring-cyclotrons in theRIBF accelerator complex from January to December 2015is presented. Table 1 summarizes the accelerated beams inthese cyclotrons. The availability is defined by the ratio of
the actual beam time to the scheduled beam time, which isan index of the reliability of beam supply. The delivered
beam time in 2015 was 3173.1 h. The ratio of experimentsthat used the beam extracted from the SRC and the otheraccelerators was 75% (2388.6 h) and 25%.
The 238U beam was supplied for three periods as follows:
1) Mar. 25th to Apr. 17th for five experiments
2) Apr. 27th to May 8th for two experiments3) Oct. 19th to Nov. 14th for eight experiments.
A maximum beam intensity of 48.8 particle nA wasachieved owing to several factors, such as the increase of
the beam current in the ion source, conversion of theinjection buncher from the mesh type to cavity type,adoption of a new carbon material for the rotating chargestripper,1) improvement of the transmission efficiency in thecyclotrons, and improvement of the vacuum in the RRC.
The polarized deuteron beam was supplied from May
11th to 16th. Although the energy (190 MeV/u) was lower
than the certified energy according to the design of SRC(250 MeV/u for M/q = 2 ions), a single-turn extraction wasachieved at the acceleration test before the experiment.
The 78Kr beam was supplied in six experiments with amaximum intensity of 310 particle nA, in theRILAC2-RRC-fRC-IRC-SRC mode for the first time (May23rd to Jun. 22nd). The high-intensity beam production test
was performed using an exit beam dump in the BigRIPS,
and a beam power of 13.1 kW (486 particle nA) wasobtained, which was the power record in the RIBF.
The 48Ca beam was supplied in four experiments (Nov.
17th to Dec. 4th). The maximum intensity reached 689
particle nA owing to the improvement in the ion source andtransmission efficiency by the refinement of the rotating
charge stripper.
For the machine study, a test to transport the beam
extracted from the IRC to E5B was performed. The 40Ar
beam was successfully accelerated up to 160 MeV/u in theAVF-RRC-IRC mode and transported to the E5B. In
addition, 4He was accelerated in the RILAC2-RRC mode
for the first time to be extracted from the RRC. The beam
current shown in the table is the converted value to a dutyof 100% (the measured current was 0.86 particle PA with aduty of 0.9%).
For the experiments that used a beam extracted from theRRC, 48Ca and 12C (RIPS), 84Kr for industrial use (E5A),
86
Kr for the JAXA group (E3A), and 136Xe for theKEK/KISS group (E2A) were supplied. In addition,biological experiments (E5B) were conducted as usual.

Table 1. Summary of the accelerated beams in 2015

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

Reference㸨1㸨21) H. Hasebe et al.: in this report.

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