The 13th Symposium on Accelerator Science and Technology, Suita, Osaka, Japan, October 2001

Present Status of the RIKEN Accelerator Research Facility (RARF)
M. Kase, T. Kageyama, M. Nagase, S. Kohara, T. Nakagawa, E. Ikezawa, M. Fujimaki,
N. Fukunishi, S. Numata, 0. Kamigaito, M. Kidera, A. Yoneda, M. Komiyama, I. Yokoyama,
H. Isshiki*, H. Akagi*, R. Abe*, N. Tsukiori*, K. Takahashi*, T. Maie*, R. Ohta*, K. Kobayashi*,
M. Nishida*, T. Aihara*, T. Ohki*, H. Hasebe*, H. Yamauchi*, A. Uchiyama*,
A. Goto, andY. Yano
The Inst. of Physical and Chemical Research (RIKEN), Wako-shi, Saitama 351-0198 Japan* SHI Accelerator Service, Ltd.

1 Introduction
The RARF (RIKEN Accelerator Research Facility) has
an accelerator complex consisting of the K540 RIKEN Ring
Cyclotron (RRC) as a main accelerator and its two injectors;
frequency-variable RIKEN heavy-ion linac (RILAC) andK70 A VF Cyclotron (AVF). A present layout of theseaccelerators and their beam lines are shown in Fig. I. The
combination of RILAC-RRC, which started its operation in1986, has provided ion beams with a relatively low energy(5-40MeV/u) but covering the almost full mass range(A=4-209). On the other hands, that of AVF-RRC, whichstarted in 1989, can accelerate ion beams with high energies(70-135MeV/u) and with a mass number less than 86(normally less than 40).
The construction RI beam factory (RIBF) project is now
in progress[!] on a site adjacent to the RARF building.
Since the RILAC-RRC configuration will play a importantrole as an injector to RIBF, many improvements should bedone.
Also according to the agreement on the collaboration
between RIKEN and Center of Nuclear Science (CNS) ofTokyo university, some other improvements have been donein the RARF. They are based upon (1) To keep research
activities of RARF at a high level until the RIBF project iscompleted, and (2) to use the AVF efficiently after theRIBF is completed.
2. Operation
The RRC together with the AVF and the RILAC haveprovided routinely a beam time of more than 4400 hours
through a year since 1993. In these two years, this value
decreased by 10-15% due to the construction of RIBF or
More than fifty kinds ofsome machine improvements.
ion beams have been prepared every year. These beams
have been delivered to experiments on a variety of fields,such as nuclear physics, atom and solid-state physics,
radiochemistry, nuclear chemistry, and radiation biology.
See caption of Fig.l for details of these researches.

3. The Projects ofRIKEN-CNS collaboration
Since the contract between RIKEN and CNS of Tokyo
University was made in 1999, the following projects havebeen planed and carried out concerning the RARF.

1) The 14GHz ECR, which had been in Tanashi campusof CNS, was moved to RIKEN and installed the ion
source room of A VF.
2) The two 45-deg dipole magnets between horizontal
beam line from ion source and vertical injection line of
A VF was replaced into a new horizontally-rotationable
As the result, the switch of90-deg dipole magnet.
more than one ECR ion source became possible forshort time, keeping the vertical injection line for thepolarized ion source as before.
3) A flat top system was added to cavities of AVF. An
efficient extraction of a high quality beam are expected
at AVF[2].
4) A new beam transport line from AVF to present beamline of RRC was designed and was partially completed
at present.
5) Two large scale apparatus of nuclear physics
experiment were moved in RARF. The installations ofCRIB and P A were completed in E7 and E2
respectively.
6) The maximum energy of RILAC was upgraded from4 to 6MeV/u. Four linac cavities were added to the firstunit of CSM (see the next chapter for the details) which
had been completed in 1999.
7) A new beam line, which is used exclusively by CNS,
was built in a target room of RILAC. The experimentfor university students will be done using this beamcourse.
4. CSM and Energy Upgrade of RILAC
The Charge State Multiplier (CSM) has been proposed inorder to increase the charge state of the ions that areinjected into RRC[3]. At the final stage, it will become acombination of six acceleration cavities, a charge stripper,
and three deceleration cavities. In 1999, the first unit ofCSM, consisting of two acceleration cavities and one
deceleration cavity, has been constructed[4]. These cavities
are frequency-variable between 36 to 76 MHz, being
operated the second harmonic of RILAC frequency.
In 2000, in collaboration with CNS of Tokyo University,
the rest of four acceleration cavities were constructed.
These cavities are operated at the fixed frequency of 75.5
MHz. The six cavities are installed just after RILAC as abooster of RILAC[5]. As the result these six cavities can- 43-

The 13th Symposium on Accelerator Science and Technology, Suita, Osaka, Japan, October 2001

Fig. 1
A layout of RARF accelerators and beam lines. The
researches and constructions. beeing performed recently are asfollows. [El]; A test of nuclear detector and some RIPS-likeexperiments using a secondary beam course newly rearranged.
[E2]; A large apparatus of Particle Analyzer (PA) installed in2000 (by CNS). [E3]; RI productions for the purpose of themultitracer technique. The single event of electronic device(by NASDA). [E4]; Nuclear physics experiments at SMART
using the polarized deuteron beams. The high energy neutron
source for a detector test and for data-taking of neutron
shielding. [E5]; Biological researches such as the mutation
breeding, radiation biology, and the bioresource.
Development of superconducting material and heavy-ion
induced acoustic emission.
[E6]; Nuclear physics
experiments using RIPS (Riken Projectile-fragment
Separator), such as the exotic nucleus structure of neutron-richparticle, nucleus astrophysics, and nuclear synthesis far fromthe stable line. Production of high-spin isometric beam, andIon-trap of energetic radioactive ions. [E7]; a spectrometer ofCRIB (CNS low-energy RI Beam separator) installed. Nuclear
physics experiments of elastic resonance scattering onunstable nuclei using AVF beams. (by CNS). [RILAC-e3];
GARIS installed in 2000. Search for new super-heavy
elements via a sub-barrier fusion reaction.
II I I I II I I I I!OmNishina Memorial Building- 44-5m0

The 13th Symposium on Accelerator Science and Technology, Suita, Osaka, Japan, October 2001

accelerate ions with mass-to-charge ratio of less than 5.6 up
to the energy of 5.85MeV/u. The total voltage-gain of thebooster is 16 MV, which is the same as that of the RILAC.
5. GARIS experiment and H8 RRC acceleration.
The energy upgrade of RILAC permits the two newschemes at the RARF, even if the CSM is not fullycompleted.
One is that a search for superheavy elements with theGARIS (GAs-filled Recoil Isotope Separator) become
available at RILAC, which had been done at El target
room of RRC beam line. A very intense beam with aenergy around 5.2MeV/u are required on this experiment.
In summer of 2000, the GARIS apparatus (a total weight is65 t) was moved from El and installed in a target room ofRILAC. Compared with the before, more intense beamwill be expected, and more beam time can be shared for thisresearch.
The other is that a new configuration of RILAC-CSMRRC becomes useful to improve a beam intensity. The RRC
was designed to operate with a harmonic number of 9 in thecase of RILAC-RRC. Due to the energy-variability ofRILAC, the RRC has been operated with a higher
harmonics such as 10, 11, and 12 as well as the designed
one. In the RILAC-CSM-RRC, the RRC can be operated
with a harmonics of 8, 7 and 6. Some beams, which had
been obtained only in the AVF-RRC, can be accelerated in
the new scheme of RILAC-CSM-RRC with a much more
intensity, because lower-charge-state ions can be taken at
the ion source of RILAC and also because a transmission
efficiency of RILAC is better than AVF. Such beams, someof which are very important for nuclear phyics experiments,
are listed table 1. A test of the RILAC-CSM-RRC with h=8
will be tried soon.
6. Developments and improvements
Because the RILAC-RRC will be an injector to RIBF,
some developments and improvements have been done
continuously. A superconducting ECR has been developedand its beam test is now in progress[6]. As the method toinsert a solid element to ECR plasma, a micro-oven system
A beamwas installed to the 18GHz ECR at RILAC.
increase.
toexpected
beintensity of some solid ions will
A charge stripping of ions after RILAC will be a very
essential mater for the RIBF. Recently a long-lived carbon
foil has been successfully produced[?]. Also liquid typestripper has been developed[8].
A control system has been replaced by the new one using
EPICS[9]. The low-level interfaces (CAMAC-CIM-DIM,GPIB) were kept as before. The new control system covers
not only the whole accelerator but also experimental
apparatus such as RIPS and SMART. A new interface,which had been developed for power supplies in RIBF, isalso included to the new system and tested in a routine
operation.
RF amplifiers for cavities #5, #6 were replaced into newones. The new amplifiers are almost same as those of ring
cyclotrons (IRC&SRC) in RIBF and analogous to those ofRRC. The spared parts for these amplifiers can becommonly used.
References[1] Y. Yano, "RIKEN Rl beam factory", in this proceedings.
[2] S. Kohara et al., "Construction of flat-top system in the RIKEN
AVF cyclotron", in this proceedings.
[3] Y. Yano et al., Proc. 1997 Particle Accelerator Conf. (PAC97),
Vancouver, Canada, May 1997, p. 930 (1997).
[4] 0. Karnigaito et al., RIKEN Accelerator Progress Report 34,p.322 (2001).
[5] E. Ikezawa et al. "An energy upgrade of RIKEN heavy ion
linac (RILAC)", in this proceedings.
[6] T. Nakagawa et al., "Intense beam production from RIKEN
18GHz ECRIS and liquid He-free SC-ECR", Proc. of 19th Int.
Conf. on Ion Source.
[7] H. Hasebe et al., "Development of long-lived carbon foils", inthis proceedings.
[8] H. Akiyoshi et al., "Liquid film stripper for RIKEN RI beamfactory", in this proceedings.
[9] M. Komiyama et al., "New control system for the RIKEN Ring
Cyclotron using EPICS", in this proceedings.

Table 1. Upgrade of Beam intensities with CSM(Expected Data)(Present Data)

RILAC -+ CSM -+ RRC

AVF-+ RRC

IonQj

(MeV/n)-2851

135 (5)10+ -Qf14+Stripping after CSM

BeamStripping after AVF

ERRC> (h.oc)

Euc. (h,.c)(%}

intens.
(pnA)

soso

124 (6)

E.v;

effi.

(MeV/n)
7.0

Qj

Qt

(MeVIn)6+- 14+

Beam

Ecs..

effi.

(MeV/n)(%)

intens.
(pnA)

6.5

40

700

RILAC(37.8MHz)+A1+A2+A3-tA4-tAS-tA6+RRC
180

100 (S)

6-t .... 8-t

5.5

4-t ... 8+

86 (7)

90 1 250

4.7

85 1 >1000

RILAC(37.8MHz)+A1-tA2+A3+A4+RRC~ 0Ar

95 (5)

111+ .... 17+

5.2

42

1 908+ -> 17+

86 (7)

5.745 1 >1000

RILAC(37.8MHz)+A 1+A2+A3+A4+A5+(A6)+01 +RRC

4sca

70 (5}

111+ -+ 18+

4.0

33 1

86 (7)

4I

9+ ... 20+

5.7

1s 1 800

RILAC(37 .8MHz)+A 1+A2+A3-tA4+A5+(A6)+01 +RRC

s&Kr

70 (5)

120+ ... 31+

4.08I

66 (8)

116+ ... 31+

3.9

7

I 100

RILAC(38.2MHz)+A 1-tA2+01 +RRC

45-