JAERI-Conf 95-021

PA04
STATUS REPORT ON JAERI-A VF CYCLOTRON
Kazuo ARAKAWA, Yoshiteru NAKAMURA, Watalu YOKOTA, Takayuki NARA,Takashi AGEMATSU, Suswnu OKUMURA, Ilcuo ISHIBORI and Mitsuhiro FUKUDA.
Takasaki Radiation Chemistry Research Establishment, Japan Atomic Energy Research Institute,1233, Watanuki-machi, Takasaki, Gunma 370-12, Japan.
researchers, the accelerated particles, their energies and thebeam courses were changed as shown in Table 1.

Abstract
The JAERI AVF cyclotron has been used for experiments
since January 1992. The routine operation of the cyclotron
began in September 1992.
The total operation times
amounted to 10,000 hours in February 1995.
So far,twenty-five ion species for ranging from hydrogen throughxenon with energies of 10 - 520 MeV were used forexperiments. This paper report status on the performanceand operation of the JAERI AVF cyclotron.

3500 ~--------------------------~
3000

g2sooQ).........e 2000

1. Introduction.§ 1500~

The TIARA (Takasaki Ion accelerators for Advanced
Radiation Application) facilities have been constructed at
the Takasaki Radiation Chemistry Research Establishmentof Japan Atomic Energy Research Institute (JAERI) since1987 for a materials science project using various ion beams
in a wide range of acceleration energy.
The facilities
consist of an AVF cyclotron and three different types ofelectrostatic accelerators: a 3MV tandem accelerator, a 3 MV
single-ended accelerator and 0.4 MV ion implanter.
Large A VF cyclotron , so far, have been used mostly for
fundamental nuclear physics and medical application toradiation therapy and radioisotope production.
Ourcyclotron 1•2> is mainly used for R&D in materials scienceand other irradiation purposes. These applications of thecyclotron require that many kinds of light and heavy ionscan be accelerated in a wide range of energies. To meet therequirement, continuing efforts have been made on new beamdevelopment, improvement of beam extraction andtransmission, etc.
The operation of the AVF cyclotron for experiment wasstarted from 1992 in daily operation mode on a trial base.
The weekly continuous operation was started from
September 1992. The total operation times amounted to10,000 hours in February 1995.

~Q'lOOO
50001991

1992

1993

1994

Financial years• ExperimentfSI Beam development
1:1 Training

1111 Visitors use with charges
ll:aTunig
D Acceptance test

Fig. 1 .Statistics .of the cyclotron operation from1991 to 1994.

3000

g 2500Q)

e 2ooo2. Present Status·p

2.1 Operation
The JAERI AVF cyclotron is usually operated weekly.
The yearly operation time is divided into three beam-time
periods, each of which consists of 11 weeks of beam-times
and allocated to experiments by Program Advisory
Committee. Three weeks for maintenance and additional
beam-times and about two weeks of operation intervene
between the programmed beam-times. The experiment planand beam-times are allotted for each period. The weekly
operation is usually carried out continuously from Monday
morning till Friday evening. Regular over-haul was carriedout for 4 weeks in the summer.
Operation statistics of the cyclotron during past 4 years
are shown in Fig. 1. The percentage of time in last twoyears used for experiments, beam developments and tuning
were about 82%, 8% and 10%, respectively. The accelerated
particles and their beam time are also shown in Fig. 2. The
beam time for light ions exceed 50% of all as seen in Fig. 2.
In order to meet the requests from many groups of~c::.9 1500

0'~ 1000
50001991

1992

1993

1994

Financial years.H IJD IS14He ~Ne E;Ar IDC 1::30 BKrFig. 2 Statistics of the beam time from 1991 to 1994.
2.2 Maintenance and Status
The beam extraction system consists of an electrostatic
deflector and a magnetic channel and also of a gradient-32-JAERI-Conf 95-021

corrector to focus the beam horizontally. The positions of
the deflector and the magnetic channel can be controlled
remotely. However, the position of the gradient correctorof a passive type could not be moved remotely. Recently,
the gradient corrector was replaced by remote driving typeone for easily optimizing a focus the beam horizontallyfrom cyclotron. A RF amplifiers (EIMAC 4CW800B and4CW50000E) were also replaced by new ones in the yearly
overhaul.

Table 2
Results of extracted intensity and overall transmission.
Ion

H+

Table 1Frequency of particle, energy and beam course change in FY.

FY1992
1993
1994

Particle
424370

Energy47
51
74

Beam Course64123145

A baffle slit system at the extraction hole of theacceleration chamber in the cyclotron was replaced byremote driving one for easily control the slit width. And weadded the plate to this system in order to measure the total
To measure the beam profile from thebeam currents.
cyclotron, the single-wire profile monitor was installed tojust after the gradient corrector.
The accumulation of induced radioactivity in theacceleration chamber is making it more difficult to conduct
maintenance work inside the cyclotron (maximum dose rate
The strongest source of radiation is theis 25 mSv/h).
The septum electrodes of theelectrostatic deflector.
Furthermore, wedeflector were replaced by new ones.
prepared a set of new deflector for rapid replacement in caseof trouble. For the protection against radiation hazards,
however, it will be necessary to replace some of the strongly
activated parts, such as probe-head, magnetic channel, andmagnetic channel probe-head.
3. Beam Development
3.1 Extraction Current and Transmission
Particles accelerated and extracted so far are listed in Table
2. The extraction efficiency is defined by the ratio of thebeam current measured with the main probe at r=900 mm tothat with the Faraday cup (FC) just after cyclotron. The
average extraction efficiencies for harmonic 1, 2 and 3 are
56.0%, 65.5% and 56.3%, respectively.
The overall transmission efficiency is defined by the ratioof the beam current with the FC just after analyzing magnet
at the injection line to that with FC just after cyclotron.
The average transmission efficiencies for harmonic 1, 2 andRecently it
3 are 13.6%, 17% and 12.7%, respectively.
increased up to 15-20%. The best extraction and overalltransmission efficiency was 86% for 330 MeV 40 Ar 11 + and
26% for 20 MeV H+, respectively. The maximum beam
currents of heavy ions such as Ne, Ar and Kr mainly dependon the ability of the ion source.
3.2 Single pulse Extraction
The beam chopping system consists of a pulse voltagechopper (P-chopper) and a sinusoidal voltage chopper (Schopper)3>. The P-chopper was made to chop DC beams
from the ion sourc.es into pulse beam in the injection line.
The S-chopper was made to extract a single beam pulse after
The single pulses werethe exit of the cyclotron.
successfully extracted for 70 MeV H+ and 175 MeV 40 Ar8+
ions using a chopping system as shown in Table 3.

4He2+
12cs+
16Q5+
16c6+
16Q7+
20Ne6+
20Ne7+
20Ne8+
36Ar8+
36Ar10+40Ar8+
40Ar11+
40Ar13+
84Kr20+129Xe23+

Overall
Energ Extracted Extraction
Intensity Efficiency Transmission
y(%)
(%)
(MeV)
(eJlA)
10
20
30
45
50
60
70
90
1035
50
2050
100
220
100
160
225
120
260
350
195
195
175
330
460
520
450

125.0
2.2
30
5551011
41
21
5.5
20
100.251.7
1.90.2
1.60.331.5
2.5
0.30
3.0
0.6
0.1
0.045
0.20

68

77
67
79
4457
4248
395949
69
62
62

77
3458
54
53
70
63
63
4373
86
63
72
72

1326
2214
14
22
12
7.7
7.4
4.6
7.2
11
17
10
22
8.1
21
1018
19
23
13
11
15
20
24
20
11

3.3 Measurements of Absolute Beam energy
The energy of the ion particle has been measured
absolutely by using the crossover technique4>. This
technique is based on scattering kinematics, in particular thevariation with the angle of the energy of the particles
scattered by elastic and inelastic processes from deferent
It requires a target consisting of atarget nuclei.
homogeneous mixture of reference nuclei having wellknown excited states and projectile nuclei. The absoluteenergy of the incident particle is obtained from an angle,"crossover angle", at which the recoil projectile particles
from light nuclei and the inelastically scattered particles
from reference nuclei having well-known excited states havethe same energy.
A 10 MeV proton was chosen since the crossover angle isrelatively large and it is easy to detect the particles atbackward angles. A 2.78mg/cm2 polyethylene film was usedas the target including hydrogen and carbon nuclei to use the4.439 MeV excited state in carbon. To detect the scatteredparticles at around the crossover angle, a semiconductor
detector was mounted on a movable arm.
Figure 3 shows a typical pulse height spectrum obtainedat an scattering angle of 40• with a nominal 10 MeV proton
The left peak is inelastic
in the scattering chamber.

-33-JAERI-Conf 95-021

scattering on carbon nuclei and the right one is elastic
scattering on hydrogen nuclei.
The relationship between the scattered angles and thepulse heights in the both interactions is shown in Fig. 4.
The crossover angle was evaluated from the crossing pointof the interpolating lines for the energies of the elastic andTo compensate an asymmetric
the inelastic scattering.
factor of the scattering geometry, left and right angle
measurements were carried out.
The average value of the crossover angle obtained fromboth angles was 44.3• . The absolute beam energy wasevaluated at 9.9 MeV in this case. The uncertainty of themeasurement is now under estimation.

expensive. Tubes from gas cylinders are connected to thecommon line will be less than 3 cm 3 • Now it is used for
36 Ar and 129Xe. Test generation of metallic ions are carriedout by using insertion of ceramic rods into ECR plasma.
Ions of Ni are generated fmm NiO and Cr are CrSi2 andCr 203. Though the insertion depth was not optimized,maximum charge states are 17 for Ni and 15 for Cr, and ion
beam currents are enough for acceleration by the cyclotron
These materials were chosen
as shown in Table 4 5 >.
according to the result obtained previously by generation ofAI, Mo, B and La ions, and beam stability were good.
Table 3Results of single pulse extraction.

2000

rn 1600 z
z<(Iparticle
energypulse interval+40deg

1200

()

U51- 800z

C inelastic

:J

8 400
0700

Fig. 3

pulse widthcharge
detector

1000
900
800
PULSE HEIGHT (CHANNEL)

Beamcurrents(ellA)~--.. -PULSE HEIGHT (CHANNEL) C+H(E~4.4MEV)..,_-~-----.--~l........--.--,-rr--r--.--r-o~---.·-,·-, 1 --,-----.~---,---,--,---::J' 900'.

w""zz 850<(•""•LEFT CROSSOVER"'·"

IS2. 800~70MeV
2.11 jlS
1.27~-ts

1.95 ns
2*10-15 C/pulse
Sintilator

17+16+15+14+13+12+11+10+9+8+

NiO
ssNi

CrSi252cr

Cr20 352cr

0.5
1.0
1.8
2.8
3.8
4.0

0.5
1.8

0.5
1.2

4.0
5.8

1.9
2.7

5.2
4.5

1.5
0.9

4.4

2.1
1.2

·--·---..--·--~·~~--"', . --·---·-.a.--..--... -CD 750iii

I45.57deg

w 700

References"~:Ja... 650' '•600
3840424446485052SCATIERING ANGLE(deg)Fig. 4175 MeV
3.3 jlS
4.75 llS
7*10- 14 C/pulse
SSD

Material~~e- PULSE HEIGHT (CHANNEL) H+H

950

H+Table4
Extracted beam current for ceramic roads.

1100

Pulse height spectrum at an scattering angle of 40
deg. for a nominal 10 MeV proton.

40Ar8+

Relationship between the scattering angle and thepulse height for the elastic scattering and theinelastic scattering.

3.4 Test of Metallic Ion Generation
The ECR ion beams are presently used for two purposes;(1) injection of highly charged ion beam into the AVF
cyclotron, (2) study and development of ECR for highcharged ion beams of gaseous and solid elements. A newgas feed was added for isotope gases which are usually very

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T.Agematsu, S.Okumura, I.Ishibori, T.Karasawa,
R.Tanaka, S.Shimizu, T.Tachikawa, Y.Hayashi, K.lshii,and T.Satoh, Proc. 13th int. Conf. on Cyclotron andTheir Applications, Vancouver, Canada, pp.l19-122(1992).
2) K.Arakawa, Y.Nakamura, W.Yokota, M.Fukuda, T.Nara,T.Agematsu, S.OKumura and I.Ishibori, Proc. 9th Sympo.
on Accele. Sci. and Tech., Tsukuba, Japan, Aug. pp.202204 (1993).
3)W.Yokota, M.Fukuda, K.Arakawa, Y.Nakamura, T.Nara,T.Agematsu, S.Okumura and I.Ishibori, Proc. Int. Conf.
on Cyclotron and Their Applications, Vancouver,
Canada, pp.581-584 (1992).
4)B.M.Bardin and M.E.Rickey, Rev. Sci. Instr. 35(1964)
902-903.
5) T. Nara, W.Yokota, Y.Nakamura, M.Fukuda, T.Agematsu,
S.Okumura,I.Ishibori and K.Arakawa, TIARA Annual
Report, vol.2, pp194-195 (1992).

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