PRESENT STATUS OF UVSOR"'atanabe aT. Kasuga,a H. Yonehara,abA. Uchida,a K. Sakai,a Od. Matsudo,a Td. Kinoshita,a M. Hasumoto,fa8iamazaki:a E. Nakamura,a H. Yamamoto, K. Takami,c T. Katayama, K. Yoshida, M. Kihara, and G. Saxon
ABSTRACTUVSOR
ofstatustheandfeature
Main
light source and its surrounding instruments in August
1984 are presented. UVSOR is a 600 HeV ( max.
todedicatedring
750 HeV ) electron storage
synchrotron radiation research mainly in molecular
It had been constructed since 1981 and wasscience.
Maximum current
commissioned on 10th November 1983.
The ring is composed of eightso far is 170 rnA.
and four long and four shortbending sections,
From one bending section, twostraight sections.
outlets of synchrotron radiation with horizontal angle
withA wiggler
available.
mrad are80ofwithundulator
and anmagnets
superconducting
permanent magnets have been constructed. Single bunch
The connection ofoperation was tried successfully.
monochromators to synchrotron radiation outlets isunder way.

Wavelength

Intensity
1.
Fig.
radiation in UVSOR.

distributionofsynchrotronThe orbit radius in bending magnets
the synchrotron.
In Fig. 1 is shown photon fluxof the ring is 2.2 m.
Two curves show photon flux
distribution from UVSOR.
from ordinary bending section at 600 MeV and 750 HeV,
and one curve, that from a superconductiong wiggler
40 kgauss ) at 750 HeV, which was installed at s7
The energy and the radius werestraight section.
chosen so that the photon flux covers the range fromlightabsorption edge to K-edge offundamental
elements such as carbon, nitrogen and oxygen which areincluded in many molecules. An undulator which emitts
beenlight above 150 A has
quasimonochromatic
Far infrared radiation will be utilized
constructed.
at an ordinary bending section.
2 shows the plane view of the UVSORFig.
The synchrotron and the storage ring arefacility.
underground for radiation safety. Electrons of 600 HeVINTRODUCTIONUVSOR is a dedicated VUV synchrotron light 1 source
Itsand related fields.
for molecular science
construction was started in 1981 and the first beam
The optical
was accumulated on 10th November 1983.
In thisinstruments had been constructed since 1980.
paper, main feature and the status of light source
and its surrounding instruments in August 1984 arerepresented. ~orrection of design parameters given in
Detailed descriptions
previous paper is also given.
for vacuum system, position monitor and single bunch
operation will appear in this proceedings.
The light source is a 600 MeV ( max. 750 MeV
storage ring, the injector of which is a 600 MeV
synchrotron with a 15 MeV linac. The circumference ofthe ring is 53.2 m, which is twice as long as that of0 2 4 6 8 10m
ChemicalMaterialCenterStorage Ring

Instrument
CenterPower Sources

HallwayFig.
abc2.

Plane

viewofUVSOR

facility.

Institute for Molecular Science, Okazaki 444,
Japan.
University,
NagoyaChemistry,
Department ofChigusaku, Nagoya 464, Japan.
Kyoto University,
Research Reactor Institute,
Kumatori, Osaka 590-04, Japan.

def

15

Institute for Nuclear Study, University of Tokyo,
Tanashi, Tokyo 188, Japan.
Physics,
National Laboratory for High Energy
Tsukuba, Ibaraki 305, Japan.
Warrington,
Daresbury,
Laboratory,
Daresbury
WA4 4AD, U. K.

extracted from the synchrotron are transported under
the floor of the storage ring room and injected fromthe inner side of the ring.
Optical instruments are
installed around the ring.
During the injection
period, experimenter should be out of the storage ringroom and after the injection, they can reenter theroom making measurements.
Shield blocks against theradiation due to the decay of stored current will be
put up around the ring.
LINAC
The maximum energy of the linac is about 18 MeV
by the use of 7 MW klystron, The RF frequency is 2856
MHz.
Two pulse widths can be chosen, 1.5 ~s forordinary
operationand 5 ns for single
bunch
operation.
Fig. 3 shows the energy distribution of
1.5 ~s beam measured by an analyzer magnet inserted
between the exit of the linac and an entrance of an
inflector of the synchrotron,
Theenergy spread( FWHM) is 1.6 %. The total current is 40 rnA. Fig. 4
shows the beam size at the exit of the linac measured
by a wire scanned across the beam orbit. The diameter( FWHM ) is 4 mm.

Fig. 5.

In order to make tracking easy,. the excitation ofmagnets is made as follows. The quadrupole has a main
The main coils of the quadrupoles
and a sub coils.
and the coils of the bending magnets are connected inseries.
Greater part of required magnetomotive force
in the quadrupoles is obtained with the current
flowing in the main coils. The deviation of current
dependence of magnetic field in quadrupole from thatin bending magnet is compensated by adjusting thecurrent of sub coils. The main coils are excited by a
24 phase controlled thyristor rectifier backed up witha transistor chopper and sub coils are excited by twotransistor choppers.
All power supplies s~)isfy thestability requirement of the current of 4x10( peaktopeak ) in whole excitation range.
Present
operation point ( Q, Q) is ( 2.20, 1.43 ),Fig. 6 shows tfie cu¥rent wave forms of succeeding
two pulses during the acceleration time of 150 ms
observed by the core monitor. At higher current case,30 rnA is stacked with multi-turn injection, but 15 rnA
is accelerated upto 600 MeV. The cross section of the600 MeV beam is small enough to pass the aperture of
the deflector ( 5 mm x 5 mm ), due to the adiabaticand the radiation damping.
Three or four bunches are
extracted in one pulse in ordinary operation.

418 MeV

Pulse Width~

1.5 ~sFWHM
1.6 .,.

56Current of Analyzer (A)Fig. 3.

The injector synchrotron,

Energy distribution of the linac beam.

.......

~4c::J.03<:;:2cell~1uo~-L--~~-L-L--~~-30 -20 -10

010

20

30

Position(mm)Fig. 4.
Position
linac at the exit.

dependence of beam current of theSYNCHROTRON
Fig. 6.

The synchrotron is composed of six
bending
sections and six straight sections as shown in Fig. 2.
At each straight section, a doublet of quadrupoles areinstalled.
An inflector is 3located at s1 straightsection, three perturbators,
at s1 ,
s2 and s6
sections, and a fast kicker and a deflector forextraction, at s2 and s4 sections.
An RF cavity is
installed at s 5 section, the resonance frequency ofwhich is 90.12 MHz.
Electrostatic position monitorz
are set at each midpoint of quadrupole doublet.
Current monitors with a ferrite core are situated ats2 and s, sections. Fig. 5 shows the picture of thesynchrotron assembled.
The gap and the width of thebending
maggets are finally 4.8 em and 18 em,
respectively.

Current wave forms during the acceleration.
STORAGE RING

The storage ring is composed of eight bending
sections, and four long and four short straightsections as shown in Fig. 2.
At each long straightsection, two doublets of quadupoles and two steering
magnets ( vertical ) are installed, and at the
midpoint of the down-stream doublet, a skew quadrupole
is located, At each short straight section, a tripletof quadrupoles and that of sext~poles are installed.
An inflector is located at S1 straight section, three
perturbators, at s1 , s2 and s8 sections. An undulator
under magnetic field measurement will be installed ats3 section. An RF cavity excited with the same16

~10mmFig. 9. Beam profiles.
Fig. 7. The UVSOR storage ring.
these values quantitatively from the picture given in
Fig. 9, however these values seem somewhat larger thanthe design value.

frequency as the synchrotron's one and the three poles
section. A DCCT and a core
wiggler were set at S
Buttonmonitor are located ai s1 and s4 sections.
are attached at up- and down-stream ofmonitors
bending sections. The bending magnet has a correction
The bending and the quadrupole magnets of thecoil.
ring have the same cross sections as those of thesynchrotron. The field index of the bending magnet is0. Fig. 7 shows the picture of the storage ring.
Fig. 8 shows feature of accumulation and dampingof the beam observed at the end of February 1984.
current was measured by a DCCT at s1 section.
TheInjection rate was three times per second. A current
Theof 160 rnA was accumulated within 10 minutes.
lifetime in which the stored current of 100 rnA
The ~gort lifetime
decayed till 1/e was 20 minutes.
Torr withseems due to the poor vacuum of 1x10
stored beam of 100 rnA. The vacuum will be improved innear future with baking and argon discharge cleaning.
Present operating point ( Q , Q ) is ( 3.27, 2.80 ).
The betatron number shifts ~ith the increase of storedorbit
closedcorrection of theThecurrent.
Single bunch operation
distortion was made in July.
was performed with a current of 1 rnA.
200

BEAM LINES AND MONOCHROMATORSoftwo outlets
one bending section,
From
anThroughsynchrotron radiation are available.
synchrotron radiation with horizontal angle
outlet,front end of beam lines isof SO mrad can pass. Aa tightly closing valve
composed of a beam shutter,and a fast closing valve with finite conductance,
which protect the vacuum of th~ ring against accidental
Closing time of theleakage from optical systems.
Acoustic delay lines
fast closing valve is 10 ms.
which can delay the speed of the leakage, are inserted
just before entrance slits of monochromators, in thecase that the distance between the front end and theentrance slit is not longer than 10 m.
At present, three 1 m Seya-Namioka monochromators
are being connected to the beam lines, BL2A, BL2B2 andA 3 m normal incidence monochromator is being
BL7B.
connected to BL3B, a plane grating monochromator(PGM), to BL8B2 and a double crystal monochromator,
to BL7A. The beam line BL6A will serve as a far
infrared port and another PGM port.

Injection
j Stop84-2-291c

ACKNOWLEDGEMENTS
The authors wish to thank Prof. H. Inokuchi andother members of UVSOR working group for continuous
They are also grateful to the staffs
encouragement.
of Institute for Nuclear Study and Institute for Solid
State Physics, University of Tokyo, and National
Laboratory of High Energy Physics for helpful advices.

:!:~0100u~0iii

001020304050

REFERENCES

Tlme(mln.)

Fig. 8.

1) M. Watanabe et al., UVSOR-9 (1982).
2) M. Watanabe et al., IEEE Trans. NS-28 (1981) 3175.
Proc. 4th3) M. Hasumoto, K. Takami and A. Uchida,
Symp. on Accel. Sci. Tech., Saitama, 1982, p.139.
4) H. Yamamoto and T. Kasuga, Proc. 4th Symp. onAccel. Sci. Tech., Saitama, 1982, p.123.
5) 0. Matsudo, M. Hasumoto and M. Watanabe, Proc. 4thSymp. on Accel. Sci. Tech., Saitama, 1982, p.311.
6) K. Sakai, H. Yamamoto and M. Watanabe, Proc. 4th
Symp. on Accel. Sci. Tech., Saitama, 1982, p.215.

Accumulation and damping of the beam.

Fig. 9 shows two examples of profile of stored
beam at different operating condition at the beam
current of 10 rnA. The profiles change with the change
in operating condition and the amount of stored
current. Profiles in Fig. 9 look like a ellipsoid andThese pictures were taken by the use of TVa circle.
camera. The design values of 2 0 and 2 0 are 0.6 mm
and 0.4 mm. At present it is difficult tg estimate
17