IV. OPERATION RECORDS

RIKEN Accel. Prog. Rep. 54 (2021)

RIKEN Accel. Prog. Rep. 54 (2021)

Operation report on the ring cyclotrons in the RIBF accelerator
complex
S. Ishikawa,∗1 K. Suda,∗2 T. Dantsuka,∗2 M. Fujimaki,∗2 T. Fujinawa,∗2 N. Fukunishi,∗2 S. Fukuzawa,∗1M. Hamanaka,∗1 H. Hasebe,∗2 Y. Higurashi,∗2 E. Ikezawa,∗2 H. Imao,∗2 O. Kamigaito,∗2 Y. Kanai,∗2 M. Kase,∗2M. Kidera,∗2 K. Kobayashi,∗1 M. Komiyama,∗2 R. Koyama,∗1 K. Kumagai,∗2 T. Maie,∗2 T. Nagatomo,∗2T. Nakagawa,∗2 M. Nakamura,∗2 T. Nakamura,∗1 M. Nishida,∗1 M. Nishimura,∗1 J. Ohnishi,∗2 H. Okuno,∗2K. Ozeki,∗2 N. Sakamoto,∗2 J. Shibata,∗1 N. Tsukiori,∗1 A. Uchiyama,∗2 S. Watanabe,∗2 T. Watanabe,∗2Y. Watanabe,∗2 K. Yamada,∗2 K. Yadomi,∗1 and H. Yamasawa∗2The operation report of the ring cyclotrons in theRIBF accelerator complex from Jan. to Dec. 2020 is presented. Table 1 presents a summary of the beams accelerated by these cyclotrons. The availability is defined as
the ratio of the actual beam service time to the scheduled beam service time, which is an index of the stable
Operation of accelerators. In calculating each availability, for beam service times that were completed earlier
than scheduled, the scheduled times are identified withthe actual times. Multiple experiments supplying identical beams are treated as one and presented in a row. The
total actual beam service time was 1639.1 h. The ratioof the beam service times between the experiments conducted in the old facility (RARF) and the new facility(RIBF) was 54:46.
In the RARF, the actual beam service time was884.5 h, and the availability was 95.7%. In the RIBF, twobeam services were carried out. The actual beam service
time was 754.6 h, and the availability was 89.8%. Due tothe declaration of a state of emergency in relation to theCOVID-19 infection, experiments were cancelled for twomonths from April. Vacuum leak occurred at the RRC
resonator No.1 in May, and weld repair was carried out.
Due to the repair, all the beam service times scheduledin June were cancelled.
In the 238 U beam supply for eight experiments, weachieved a maximum beam intensity of 116 particle nA,
which is 1.2 times higher than that of the previous beamservice in Nov. 2019. The highest record was obtained
due to the upgrade of the RRC resonators1,2) and thechange in gap spacing of the RRC-EDC in 2018, andthe relocation of the fRC-EIC in 2020. The beam supply
was stopped for 8 days due to the repair of the SRC-EDC
and SRC-Resonator 2 (RES2). A septum electrode of theEDC was damaged by a loss of the high intensity beams.
After the exchange of the EDC, a beam intensity wasreduced to 70 particle nA to prevent EDC damage again.
RES2 could not be excited because the contact fingers
for the coarse tuning plate was partially burned out by ahigh RF input power. The damaged contact fingers wereexchanged. The beam service time was 510.5 h, and theavailability was 81.8%.
In the 70 Zn beam supply for three experiments, werecorded the highest beam intensity of 782 particle nA,
which is 3.1 times higher than that of the previous beamservice in May 2017. The increase of beam intensity wasachieved due to the improvement of the oven in the ion
source and of the beam tuning based on the beam supply parameters obtained by a scaling of that for 238 U.
The beam service time was 244.2 h, and the availability
was 113.1% because the tuning time was shorter thanplanned and the experiment was started ahead of schedule.
References

1) K. Yamada et al., RIKEN Accel. Prog. Rep. 52, 13 (2019).
2) K. Yamada et al., J. Part. Accel. Soc. Jpn. 17, 159 (2020).

Table 1. Summary of the accelerated beams in 2020.
Energy Acceleration
Beamparticle (MeV/nucleon)
modeCN20Ne22Ne40
Ar
56Fe84
Kr
4He
1214

RARF

136
4070

RIBF

∗1∗2135
135
135
7095
9070
7.25

Xe 10.75

Ar
Zn

160
345

U345

238

AVF-RRCRILAC2-RRC
AVF-RRC-IRC
RILAC2-RRC-fRC-IRC-SRC

Beam intensity(particle nA)
Requested Actual
E5B (Biology)
1450.0E3B (RI production)
500
571.0
ESB (Biology)
1270.0E6 (Material)
250
300.0
E5A (Material)
126.5
ESB (Biology)
1
3.5
E5A (Material)
19.7
A10 (MS)
18300
590.0
E2B (KEK/KISS)
250
325.0
/E3A (Material)
E5B (Biology)
123.3
BigRIPS/ZD
>600
782.0
BigRIPS/ZD
>60
116.3
/Rare-RI RingTotal
Beam course

Beam service
Availability
time (h)(%)
Scheduled Actual
27.5
9.2
100.0
48.0
49.5
103.2
4.0
2.6
100.0
108.0
107.9
99.9
84.0
86.1
102.5
6.0
2.1
100.0
240.0
205.8
85.6
33.6
33.6
100.0
381.0

371.5

97.5

23.5
216.0

16.2
244.2

100.0
113.1

624.0

510.5

81.8

1795.6

1639.1

92.9

SHI Accelerator Service Ltd.
RIKEN Nishina Center- 184 -1