Proceedings of the 25th Linear Accelerator Meeting in Japan (July 12-14, 2000, Himeji, Japan)[12P-02]
Current Status of REFER at Hiroshima UniversityS.MasudaA), I. Endo*), T. Takahashi, K. MatsukadoA), Y. Okazaki, K. Ikematsu, T. Ohnishi,
S. Matsuno, D. Iseki, M.Kimura, K. Nakamura, A. Sharafutdinov.
Graduate School of Advanced Sciences of Matter, Hiroshima University,
1-3-1 Kagamiyama, Higashi-Hiroshima, 739-8526, JapanA)

Venture Business Laboratory, Hiroshima University,
2-131 Kagamiyama, Higashi-Hiroshima, 739-8527, Japan
Abstract
REFER (Relativistic Electron Facility for Education and Research) electron circulating ring at Hiroshima
University Venture Business Laboratory is a small electron ring, 13.7 meters in circumference. This device is used fordevelopment of an x-ray source based on possible new principles such as parametric x-ray generation and for education
in beam physics. This paper reports the current status of the REFER electron ring.
1. Introduction

such as parametric x-ray (PXR) generation / laser

Relativistic electron beam accelerators have sofar been developed mainly for investigation in thebackward compton scattering (LBS), development of
x-ray detectors, etc.

elementary particle physics. On the other hand, there

Detail of REFER electron ring is described inhas been a growing interest in applications of relativistic

the next section.

electron beam to another fields in recent years. For

status of REFER.

Section 3 summarizes the present

instance, one of the expected application is developmentof x-ray sources for industrial[1], medical [2,3] andscientific[4] field.

2. REFER Electron Ring

For these applications, small

devices are required.

Figure 1 shows an arrangement of magnets in
REFER electron ring. The electron ring consists of four

REFER electron ring is a compact electron

short drift spaces (0.5 meters long), four long drift

circulating ring for application research of thespaces (1.5 meter long * 2 and 2 meters long * 2) andrelativistic electron beam and for education of beameight bending magnets. Circumference of the ring isphysics. This device was installed at Hiroshima

13.7 meters. Four couples of the bending magnets are

University Venture Business Laboratory in 1997. The

arranged at corners of the ring so that four long drift

electron beam energy is 150 MeV, which is generated

spaces are secured. Combined function type bendingby the microtron [5] at Hiroshima Synchrotron

magnets (n value = 0.5) are used. The bending angle ofRadiation Center [6]. A beam extraction line is attachedeach bending magnet is 45 degrees and the curvature ofto the REFER electron ring. The electron beam can bebending is 0.75 meters. Horizontal and vertical tune ofslowly extracted from the main ring. The electron beam

REFER electron ring is 1.25 and 1.25, respectively,at REFER is utilized for investigation and education ofunder this configuration. An injection septum magnet,

the beam physics, development of new x-ray source

an extraction kicker magnet and a target chamber areplaced in the drift spaces of 2 meters long. Two bump*)

I. Endo, 0824-24-7372,magnets, an extraction septum magnet, a beam scraper

iendo@hiroshima-u.ac.jp

and a beam absorber are placed in the drift spaces of 1.5−132−Figure 1. Configuration of REFER electron circulating ring.

meters long. A goniometer in the target chamber holds

collisions of circulating electrons to the injection

internal target and controls position and angle of theseptum magnet.

target. Two view ports is arranged at both ends of theAs the present REFER electron ring has nolong drift space. Vacuum of 1x10-7 is created by sevenacceleration mechanism, the energy loss of electron

sputter ion pumps and a turbo molecular pump .

beam, 59.7 eV per turn, due to synchrotron radiation isThe 150 MeV electron beam generated by the

not compensated. Deviation of the electron orbit frommicrotron [5] at Hiroshima Synchrotron Radiation

the reference orbit increases with time. Therefore, theCenter [6] is injected to REFER electron ring. The

electrons are lost at vacuum pipes after several ten

injection beam has typically 1 micro second in bunch

thousands turns.

length, peak current upto 10 milli ampares and pulse

An induction monitor observed that the peak

repetition rate of 2-100 Hz. Muti-turn injection intocurrent of the circulating electron beam is 10 milli

REFER electron ring is performed by the injection

ampares and its life time or bunch length is 3.5 ms. The

septum magnet and the bump magnets. Pulse power

observed life time agreed with that determined by thegenerators supply pulse current to coils of thoseradiation loss. Injection efficiency is estimated as 1 - 5

magnets synchronous with beam injection timing. The

percents. The synchrotron radiation from the electron

injection septum magnet puts the beam injected frombeam is focused by a system composed of a telescope,

microtron into the bump orbit. Deviation of the bumpspatial filters and lenses onto a CCD camera for beam

orbit from the reference orbit is varied from 30 milliposition and dimensions measurement. The shutter

meters to zero with time in 1 micro second to avoid

timing and the speed of the CCD camera is controlled

by an external trigger input. Figure 2 shows images ofsystem via computer are developed. The ring is operated

the synchrotron radiation at different timing. The

8 hours * 4 days per week under the condition of theelectron beam shifts to inside direction of the ring andrepetition rate of 10 Hz and the injection beam current

its size becomes larger with time as expected. It isof 2 mA. Total time of beam injection was 400 hours ininteresting to note that the beam separates into upper

last year.

and lower parts The reason for this beam behavior yet tobe understood.

The PXR experiment was conducted andsuccessful result of enhancement of x-ray generation
was obtained [7,8]. A LBS experiment was prepared
and will be conducted in this year. The REFER beam isutilized to investigation of the particle physics such as
an experiment of the coherent pair creation from acrystal target.

Furthermore, a long pulse induction

acceleration is considered as a test bench fordevelopment of small betatron. Experiments planned at
REFER in this year is listed in Table 1.
Behavior of the electron beam in REFER has
not been clear, so more machine study is needed for
improvement of beam quality.

Table 1. List of experiments planned in 2000
Coherent pair creation on monocrystalline target
Laser compton scattering
Figure 2 Synchrotron radiation images taken by CCDcamera. (a) at t = 0 (just after beam injection) (b) at t=
200 micro seconds. Shutter speed is 50 micro seconds.

X-ray intensity in Bremsstrahlung
from high-energy electrons
Induction accerelation in REFER

The extraction kicker magnet and the beam scraper
is used as perturbater for slow extraction. The extraction

Two-track separability of JLC-CDC
Study of beam position control of REFER

septum magnet slowly extracts the circulating electronbeam. The extracted electron beam is guided by abending magnet into a extraction line consists of two
quadrupole magnets.

3. Summary
Outline of REFER electron ring was described.
Equipments around REFER also has been preparedsince REFER was installed. The beam extraction line
was installed and tested. Electrons of the order of 100
per second was detected at the end of the beam
extraction line. Softwares to control the power supplies
for the magnets, the goniometer and data acquisition[1] H. Uberall. et. al., SPIE Proc.,
Short Wave Radiation Sourceces 1552 (1991) 198.
[2] H. Wiedemann, et.al., Nucl. Instr. and Meth.
A 347 (1994) 515[3] R. Carr, Nucle. Instr. and Meth. A347 (1994) 510.
[4] R. H. Pantell, et.al., in R. A. Carrigan,J.A. Ellison (Eds.), Relativistic Channeling,
NATO ASI Series, Vol. 165, Plenum Press,
New York, 1987, p.435.
[5] T. Hori, et.al., PAC'91 (1991) p2877[6] K. Yoshida, et.al., Proc. of APAC'98, (1998) p653,Tsukuba[7] K. Chouffani, et.al., American Physical Society,
Centennial meeting, March 21-27 (1999) Atlanta,Georgia, USA[8] K. Chouffani, et.al. RREPS'99 meeting,
September 1999, Baikal Lake, Russia