Control System of Himac Secondary Beam Course for Medical Use
S. Koda, A. Kitagawa, J. Yoshizawa, M. Torikoshi, M. Kanazawa, T. Murakami, K. Noda, M. Suda, Y.
Ishikawa*, J. Matsuura**, H. Okamura** and T. Usami**
National Institute of Radiological Sciences (NIRS), 4-9-1, Anagawa, Inage-ku, Chiba, 263, JAPAN*Accelerator Engineering Corporation, 2-13-1, Konakadai, Inage-ku,Chiba, 263, JAPAN**Mitsubishi Electric Corporation, 1-1-2, Wadasaki, Hyogo-ku, Kobe, 652, JAPANAbstruct
A new secondary-beam course for medical application isunder construction at NIRS. A control system enabling
automatic beam tuning was designed. In a first test of thebeam tuning, the basic tuning functions were confirmed tooperate effectively. Status of the development and theresults in the beam tuning are summarized.

number, Z, in an energy degrader of an aluminum plate at
the focus point, F1. Finally the secondary particles areseparated by A and Z numbers and are focused at a point ofF2, which satisfies the double achromatic condition. Theparticles are transported to a focus point F3 in anexperimental area[1-3].

1 Introduction
A secondary-beam course is under construction in Heavy
Ion Medical Accelerator in Chiba (HIMAC). An important
purpose of the beam course is a study of medical
application of radioactive beams. The beam course will bealso used in basic sciences such as nuclear physics. A
control system to provide radioactive beams easily andswiftly was designed.
The control system of the secondary-beam course
satisfies the following two requirements: good
reproducibility and a quick beam tuning. A control systemof a secondary-beam course for medical use is required tohave a good reproducibility of beam conditions including
energies, intensity, sizes and purity of the secondary beams.
Easy operation in beam tuning is indispensable so that
operators with no special knowledge about reaction
products can operate the beam course as a routine work.
Use of the secondary-beam course for basic sciences isrestricted to night time or the weekend so as not to interferewith the schedule of clinical trials. It is therefore importantto reduce beam-tuning time for the users of the secondarybeam course.
In order to fulfill those requirements, we developed thecontrol system which integrated the functions of dataacquisition, data analysis and device control. Without
assistance of operators, information from monitoring
detectors is analyzed, device parameters are recalculated,and new parameters are set to devices. We finally aim todevelop a control system which automatically provides
new secondary-beams with pre-programmed sequences.
2 Secondary-beam course
2.1 General view
The secondary-beam course is a projectile fragment
separator with two bending magnets, as shown in Fig. 1.
Secondary particles produced in the target are separated bya first bending magnet in according with a ratio of the mass
number and the atomic number, A/Z. The secondary
particles loses some energy depending on the atomicFig. 1 The secondary-beam course in HIMAC. Closed
squares on the beam line mean quadruple magnets.
2.2 Particle identification
For monitoring the secondary beams, TOF counters anda delta E counter are set on the beam line. The TOF
counters are plastic scintillators with a thickness of 0.5mm.
The length between the TOF start and stop counters is 10m.
The delta E counter is a silicon detector with a thickness of0.3mm. The positions of the counters are shown in Fig.1.
The A and Z numbers of secondary particles are identified
from information of velocity and energy loss measured by
the detectors.
3 Control system
The control system consists of two computers todistribute the load of control, and is connected to theexsisting control system, High Energy Beam Transport(HEBT). Relations between these computers areschematically shown in Fig. 2.
Beam-transport devices such as the quadruple magnets,
the bending magnets, the slits, the targets, and thedegraders are controlled by the device control computer
called High Energy Beam Transport Secondary ControlUnit (HEBT-SCU). HEBT-SCU is a part of the existing
control system and connected to the supervisory system.
The data acquisition computer, called Secondary Beam

Data Acquisition Unit (SB-DAU), is a complex of VME
modules supporting the mtt-link. Event data from the TOF
and the delta E counters taken by ADC modules aretransferred on the mtt-link. The data are accumulated in theSB-DAU and are transferred with an appropriate timing.
The maximum transfer rate is 10k events/sec correspondingto the maximum number of secondary particles in thesecondary beam course.

carries out analysis and calculation of device control
parameters for the received data and sends the results of thecalculation to HEBT-SCU. HEBT-SCU controls thedevices based on the parameters by the SB-GCU.

Fig. 3 Timing chart of the control system.
4 Automatic beam tuningFig 2. Control system of the secondary-beam course. The
system consists of two computers of SB-DAU, SB-GCU
and a part of HEBT control system named HEBT-SCU.
A UNIX work station, named Secondary Beam Course
Control Unit (SB-GCU), plays a main role in theautomatic-beam tuning, i.e. data analysis and parameter
calculation based on the programmed sequences. SB-GCU
also works as an man-machine interface, displaying thesorted data, status of the secondary-beam course andaccepting operation commands.
The data transfer between SB-DAU and SB-GCU issynchronized with the timing of the beam. A schematic
timing chart of the control system is shown in Fig.3.
During the time of beam-off, SB-DAU transfers the data
which are accumulated in memories of SB-DAU. SB-GCU

Automatic beam tuning is carried out by a program inSB-GCU. The program consists of three components : adata analysis, a beam-optics calculation and a process
scheduler. The data-analysis program calculates counts ofdetected secondary particles, and evaluates the average andthe dispersion of the TOF data measured by the plastic
counters and energy loss in the silicon detector of thesecondary particles. The beam-optics calculation program
calculates field strength of the magnets according to therequired conditions.
The process scheduler determines the control parametersof the devices such as magnet current or slit width by using
results of the other two programs and searches the required
optimum condition. The result of the calculations istransferred to HEBT-SCU, which controls the devices andchecks the result of device setting.
We explain the algorithm for automatic-beam tuning,taking 11C production from 12C beams as an example. Theflow chart is shown in Fig. 4. The sequence of the search is
as follows. (1) The magnetic field of the first bending
magnet is decided using the primary 12C beam. The
magnetic field is swept and the TOF (start) detector counts
the number of particles to determine the magnetic field
giving the maximum counts. (2) The magnetic field of thesecond bending magnet is similarly determined using theTOF(stop) counter. (3) The device parameters of themagnets for the secondary 11C beams is calculated based on
the magnetic field for the 12C beam. (4) As all devices areset to transport the 11C beams, 11C counts identified on a
two dimensional map, TOF and the energy loss, areintegrated and the production rate of 11C is evaluated. Themagnets and the slits between F1 and F2 are swept inpredetermined ranges and the optimum condition isdecided.

production rate and the purity is almost equal to thoseobtained in manual tuning.
In the search of the optimum condition, the magnetic field
was swept in a range of ± 0.3 % with a step of 0.05 %.
Time for beam tuning was about 40 minutes. The intensityof the primary beams were measured by an ionizationchamber in HEBT, while measurements of the secondary
beams were halted. We are preparing a non-destructive
monitor of the primary beams so that the primary andsecondary beams can be measured simultaneously. Whenthe new monitor is installed, not only reliability of themeasurements will be increased but also the tuning time
will be greatly reduced.
Table 2 Result of tuning test of 11C.
Optimum
DegraderProduction
Condition
Al (mm)Rate
Production
Rate

7

1.9 x 10-3

Table 3 Result of tuning test of 13O.
Optimum
DegraderProduction
Condition
Al (mm)Rate
Production
Rate
PurityFig. 4 Flow chart of automatic beam tuning.
5 Result of the experiment11

In a first step of the beam tuning, productions of C[4]and 13O were achieved. The 11C was employed because 11C
was a useful positron-emitter in medical applications. The
production of 13O was carried out as a test to produce asecondary particle which is distant from stable nuclei. Thetest experiment was concentrated to confirm effectivenessof the tuning algorithm. The condition in the test
experiment is shown in Table 1.
Table 1 Conditions of the test experiment
1228
Primary beam
CSi
Energy (MeV/u)
400
400
1113
Secondary BeamCO
Production targets
BeBe
Thickness (mm)7651
DegraderAlAl
Thickness (mm)7.0
3.5
Beam spill rate (sec/spill)
3.3
3.3
The results of the automatic tuning for 11C and 13O are
shown in Tables 2, 3, respectively. In the 11C production,
the maximum of the production rate was considered to bethe optimum condition. In the 13O production, bothmaximization of the production rate and the purity wereemployed to determine the optimum condtion. The

Purity(%)
98

Purity(%)

3.5

6.5 x 10-7

2.7

3.5

1.7 x 19-7

6.5

6 Summary
We are constructing the secondary beam course. In thedevelopment of the control system, the first test ofautomatic beam tuning was carried out with satisfying
results. The control system could generate the secondary
11C beam with same quality as that of manual tuning.
Acknowledgments
We are indebted to members of Lineac Laboratory andCyclotron Laboratory at RIKEN and Prof. Matsuta of
Osaka University for suggestions about the course design.
We also thank Dr. Kawachi for warm encouragement in thedevelopment.
References[1] M. Hosaka, et al., Proceedings of the 10th Symposiumon Accelerator Science and Technology, Hitachinaka ,1995, p. 410.
[2] M. Torikoshi, et al., Proceedings of International
Symposium on Non-Nucleonic Degree of Freedom
Detected in Nucleus, Osaka, to be published.
[3] S. Kouda, et al, 1997 Particle Accelerator Conference,Vancouver, B. C., Canada, 1997, to be published.
[4] M. Suda, et al, Proc. 11th Symp. Accelerator Scienceand Technology, Harima, Japan, 1997