PRESENT STATUS AND THE OPERATION OF THE RIKENACCELERATOR RESEARCH FACILITY
H. Akagi*, T. Ohki*, H. Saito*, E.Ikezawa
RIKEN (The Institute of physical and Chemical Research),Wako-Shi,Saitama351-0198Japan* SAS (SHI Accelerator Service, Ltd)
Abstract
The RARF (RIKEN Accelerator Research Facility) has
an accelerator complex consisting of the K540 RIKEN
Ring Cyclotron (RRC) as a main accelerator and its twoinjectors; variable frequency RIKEN heavy-ion linac(RILAC) and K70 AVF Cyclotron (AVF).
The RRC together with the AVF and the RILAC haveprovided routinely a beam time of more than 4400 hours
through a year since 1993. Present status of the RARF
operation and recent advances are reported.

1. Introduction
The RARF Accelerator system consists of a K540 ring
cyclotron (RRC) as a main accelerator and its twoinjectors, a variable-frequency heavy-ion linac (RILAC)
and a K70 AVF cyclotron (AVF). Recently charge state
multiplier (CSM) has been added. A layout of theseaccelerators and transport lines are shown in Fig.5. The
RILAC injection which started in 1986 provides ion
beams of almost full mass range (A=4-209), of relatively
low energy, 5-63MeV/nucleon. On the other hand, AVF
injection which started in 1989 provides ion beams at
high energies, 70-135MeV/nucleon, of lighter than A=86
(typically 40)

Ion Source

to User
AVF

Ion Source

to User

AVF
RRC h=5
Ion Source

RFQ

RILAC

to UserIon Source

RFQ

RILAC

CSM

Ion Source

RFQ

RILAC

to User

to User

RRC h=9,10,11
Ion Source

RFQ

RILAC

to User

CSM

RRC h=8

Fig.1 Performance of RRC
All beams which have ever accelerated areshown as solid circles on an energy-mass space.

Fig.2 Block diagram of Acceleration mode
RILAC : Since 1981
RRC : Since 1986
AVF : Since 1989
RFQ : Since 1996
CSM : Since 2001

RFsystem:
A variable transformer in the current source of theRRC No. 2 filament power supply burnt.

2. OPERATORS
2-1 Organization of operators
Since 1981, contracted operators from SHI Accelerator
Service, Ltd (SAS) have been operating the accelerators
under the supervision of The RARF operation staff. The
SAS operator group consists of two sub-groups, the linac
group with 6 members and the cyclotron group with 9members.

2-2 Shift workFig.3 shows a typical pattern of the shift works of theSAS operators. 24 hours are divided in two shift times
with 30 minutes overlaps. Two operators take shift for
cyclotron and one take for linac.

A sequencer unit for cooling water alarm system of theRRC No. 1 cavity was broken. Abnormal oscillation at
25.4 MHz made a water leak from a water tube in thefeeder of brand-new driver of the RILAC No. 5 tank.
Abnormal oscillation of the RILAC No. 6 tank broke
DC-blocker and a vacuum tube, and burnt the Teflon
insulator in the feeder.
The copper sheets of the shooting plates in the No. 2, 5and 6 tanks of the RILAC burnt.
Insulation of a socket for the vacuum tube of RFQ gotworse.

1
Sun

2
Mon

3Tue

4Wed

5Thu

6Fri

7SatABCDEFGHI

Teflon made insulators in the CSM tanks seemed toincrease X-rays and worsen vacuum property.
High-voltage system:
A controller of the high-voltage source for the electricdeflection channel (EDC) was broken.
A rectifier of the high-voltage source for the electricinflection channel (EIC) was broken.

Fig.3 RRC Operator Shift Pattern
RegularOvertime work
Night shift
Night shift dawn
Holiday
Rotation
A-B-C-D-E||
I- H- G- F

Spark caused vacuum leak from the insulators for theEIC and the EDC.
Cooling system:
A chillier for the ion sources was broken.
A pump of high-purity water-cooling system for RF
and the injection and extraction instruments wasbroken.

3. Yearly schedule
One year is divided to 3 experiment periods along with
2 months of maintenance periods. Shift schedule isarranged according to the schedules of experiments.

Vacuum system:
A turbo-molecular pump of 10 GHz ECR ion source
was broken.

4. MaintenanceA vacuum leak occurred in the CSM tank from badly
welded parts.

Operators are assigned to trouble-shooting and routine
maintenance activities for tasks. Maintenance is normallyscheduled twice a year in summer (1.5 month) andwinter (0.5 month).

5. Recent typical troubles
Ion source:
The sextuple permanent magnet of 10 GHz ECRion source experienced significant strength loss
(demagnetisation) after exposure to high temperature.
The insulation of plasma-chamber got worse.

A vacuum leak occurred in the RILAC No. 5 tankfrom a chapped insulator of the feeder.
A vacuum leak occurred in the AVF vacuum chamberfrom the deformed joint caused by malfunction ofvacuum system for sub-vacuum chamber.
Frequent stop of the RRC vacuum system wereexperienced, probably caused by some electric noise.
Beam diagnostics:
Cooling water of the AVF beam probe (MDP) leaked.
Insulation of the AVF MDP got worse.

Bellows of the profile monitor had a vacuum leak.

The maximum power of the high-voltage source forre-buncher should be increased.

Control system:
Renewed control system has been sometimes troubling.

The lifetime of carbon stripper foils should belengthened.

Magnet:One of the main coil of the RRC had a layer short.

7. Conclusion
The SAS operators are working on the basis of supportof the staff of RARF who shows below.

6. New acceleration scheme
Since 2001, some acceleration scheme of the RRC with
the RILAC injection was attempted in order to enlarge
the variety of beams. We experienced the operation of
h=8 schemes, e.g.:
2001/10 84Kr30+ at 63 MeV/nucleon h=8
2002/2 48Ca17+ at 63 MeV/nucleon h=8
2003/1 40Ar15+ at 63 MeV/nucleon h=8
Task awaiting solution
Beam losses while accelerating in the accelerators
should be decreased.

RIKEN Operation Staff
M. Kase, H. Akiyoshi, M. Fujimaki, S. Fujita,
Y, Higurashi, E. Ikezawa, N. Inabe, S. Ito, T. Kageyama,
O. Kamigaito, M. Kidera, S. Kohara, M. omiyama,
M. Nagase, T. Nakagawa, H. Sakamoto, N. Sakamoto,Y. Sakata, S. Yokouchi, I. Yokoyama
SAS Operators
H. Isshiki, H. Akagi, T. Maie, K. Takahashi, N. Tsukiori,
K. Kobayashi, R. Ota, M. Nishida, K. Masuda, T.
Aihara,T. Ohki, H. Hasebe, H. Yamauchi, A. Uchiyama,K. Oyamadaa#1#2#3#4b#1#2#3#4#5c#1#2#3#4#5#6h=9d#1#2#3#4#5#6

A1 A2e

#1

#2

#3#4

#5#6

A1 A2h=11h=10h=8

D1h=9Stripper
f

#1

#2

#3#4

#5#6A1 A2A3 A4g#1#2#3#4#5#6A1 A2A3 A4RILAC

to RRCh=7A5 A6h=6CSM

Fig.4 Various accelerating mode in RILAC injection scheme. The final energies after the RRC areindicated in Fig.1. The mode (a), (b), (c), and (d) have been already used for experiments (seeFig.1). The mode (e) is the normal usage of the CSM; higher charge-state of the ion is available.
Harmonic number in the RRC can be decreased to 6 when the CSM cavities are fully used (g).

Fig.5 Layout of RI Beam Factory (RIBF)

Type
Number of tankFrequency Range

RIKEN Heavy Ion Linac
RILAC
Variable Frequency Wideroe
618-40MHz

Charge State MultiplierCSMVariable Frequency Wideroe
6+1
A1,2,D1:36-76.4MHz
A3,4,5,6:75.5MHz
6MeV/nucleon

Maximum Energy
3MeV/nucleon
Charge to mass ratio
1/2-1/27
Injector
Cockcroft-Walton +8GHz ECR I.S
RFQ + 18GHz ECR I.S
RIKEN Ring cyclotron
AVF
RRC
K-value
70MeV
540MeV
Number of sectors
44Maximum magnetic field
1.7T
1. 67T
Number of cavities
22Frequency Range
12-24Mhz
18-45MHzIon source
10GHz ECR I.S
14GHz ECR I.S
P.I.S

The fixed-frequency The intermediate The superconducting
ring cyclotron
ring cyclotron
ring cyclotron
fRC
IRC
SRC
K-value
510MeV
980MeV
2500MeV
Number of sectors
446Maximum magnetic field
1.65T
1.9T
4.5T
Number of cavities
22+1
4+1
Frequency Range
36.66MHz
18-38.2MHz
18-38MHzFig.6 Specifications of RIBF Accelerators