CSR Workshop
Sep.24, 2007, UVSOR

Status of Coherent Radiation
Beamline at KURRI-LINAC
Toshiharu TAKAHASHI
Research Reactor Institute, Kyoto University (Japan)

Outline¾ Outline of KURRI-LINAC¾ Specifications of the beamline(including coherence of CTR)

¾ Spectroscopic demonstrations
on the beamline

Outline of KURRI-LINAC
It was constructed in 1964 for pulsed neutron source.
(Applied Radiation, USA)

RF: L-band (1.3GHz)
Energy: 40 MeV
Pulse width: 2ns～4µs (Multi-bunch operation)
Beam power: Max. 10kW (30MeV, 330µA)
Peak current: Max. 8A
Operation time: 2,700Hr (in 2006)
Research field (collaboration research program)z Nuclear data with TOF
z Isotope production
z Electron irradiationz Coherent radiation

since 1991
10 weeks user-time/yearLinac-based coherent radiation
disadvantage
Single-user

advantages
zHigh peak-power(the high amount of charge in a bunch～several nC)
zVarious types of coherent radiation are available.
(synchrotron, transition, diffraction, Smith-Purcell, Cherenkov)

zInteraction between electron beam and medium
is available.

Schematic diagram of the beamline
Ti window
fromL‑band LinacCTRAl foilelectronbeam

CSR is also available
with a bending magnet.

CTR
spherical mirror

Accelerator Room
Shield WallExperimental RoomParallel beam (φ15 cm)

MonochromatorInterferometer
spherical mirror

Photograph around the emission point (Target Room)

Erotc
lem
eabn

CTR

flat Al-foil

Spectrometers and detectors
spectrometers(home-made)detectors

zMartin-Puplett typeInterferometer(step scan)broadband spectrum

zGrating type monochromator(Czerny-Turner type)

monochromatic lighthigh dynamic rangezSi bolometer(Liquid-helium-cooled )high sensitivity, low noise
VBW1kHzzInSb bolometer(Liquid-helium-cooled )high sensitivity, low noise
VBW1MHzzDiode detector narrowband
fast detector VBW1GHz
zLock-in amplifier
signalacquisition zFast gated integrator for pulsed light source ofsmall duty ratioPhotograph of spectrometer

Martin-Puplett typeinterferometer

Grating type monochromator(Czerny-Turner type)(The grating is replaced by a flat mirror
under the interferometer mode.)Stability of intensity
Pulse stability

Long-time stability

VOLTAGE (V)

0.02

within ±1%0.01

00204060
TIME (min.)80

Si bolometer on the interferogram
Lock-in Amplifier (Time const.:0.1s)

Si bolometer on the interferogram
Repetition rate: 46Hz
Oscilloscope: envelope modeCorrection of fluctuation

VOLTAGE

If the intensity fluctuates due tothe trouble of the linac …..

Figure 3
Utilization of coherent ....
Takahashi et al.

2.5(a)observed
interferogram

2.0

beforecorrection

1.5

CURRENT(b)beam current
1.5
1.0
0.5

VOLTAGEVOLTAGE3

detector for monitoring fluctuation(c)monitor

21

2.5

(d)correctedinterferogram

2.0

after
correction

1.5-4-2024OPTICAL PATH DIFFERENCE (cm)Temporal structure of CTR

Diode detector
W-band75-110GHz

Macro-pulse width: 47nsenlarged
770ps (1.3GHz)

Interferogram of large optical path difference
autocorrelation

cross-correlation

cross-correlation

OUTPUT VOLTAGE (V)

0.04

0.02

Inter-bunch distance

00cm

23cm

010203040
OPTICAL PATH DIFFERENCE (cm)

46cm
50

CTR form successive bunches
0.15
max.OPD=54.2cm

high resolution-1

INTENSITY (arb. units)(∆ν=0.018cm )max.OPD=5cm

0.10

low resolution-1(∆ν=0.20cm )0.050.00

12345-1
WAVENUMBER (cm )6continuous spectrum：Δν＞f RF／c(cm-1)

70.043cm-1 for 1.3GHz

Demeritof multi-bunchzRestriction on continuous spectrum
zRestriction on delay timein the time resolved measurement

The single bunch operationis needed.

Generation of single bunch
Sub-harmonic pre-buncher
no space

High-speed avalanche-type pulser

expensive

Development andinstall on electron injector
autocorrelation

cross-correlation

770ps

OUTPUT VOLTAGE (V)

0.2

0.15

0.1

0.05

0-10

Waveform of CTR（diode detector）

degree of impurity～ 1.5%-50510 230 235 240

245 250

OPTICAL PATH DIFFERENCE (mm)Interferogram of CTR(Si bolometer)

Spectrum of CTR

equipped on the interferometer(100W; aperture φ10)

(acceptance angle: 70mrad)Pure rotational spectrum of N2O gas
T.Takahashi et al. Rev.Sci.Instrum., 69(1998)3770

ENERGY (meV)
0.5

1

1.521
TRANSMISSIVITY

J=19

J=18

J=17

J=5

J=4

J=3

J=2

J=8

J=7

J=6

J=20

Resolution: 0.2cm-1
Optical path length in N2O: 9.3m

J=1610-1
WAVENUMBER (cm )J=15

J=14J=13J=12J=115J=10J=9015

Pressure: 2×104 Pa

Absorption spectrum of OH-ion in NaCl(collaboration research with Tohoku Univ.)

ClNaCl(0.5mol%) t=5.7mm

4.22K
1.46K

ABSORPTION COEFFICIENT (cm-1)

10Na

HO

-1

1.56cm (calc.)-1

1.88cm (calc.)

8642

1.40cm-1(exp.)-1

1.95cm (exp.)

0012

3456-1WAVENUMBER (cm )789Light-pipe type
Cryostat(1.4K～4.2K)

MM-wave magneto-spectroscopy

Y.H.Matsuda et al. Physica B 346-347(2004)519(collaboration research with Okayama Univ.)

Electron spin resonance of Mn ionsin RbMn0.3Mg0.7F3Repetition rate: 17 Hz

1.277 K λ=2.5 mm

59 ms

B ~ 1 msTransmission

CTR

Macro pulse ~ 4 µs

1.00.8
FWHM = 0.235 T
0.6Time delay

4.133 T
0.4

synchronization
2.0

2.5

3.0

3.5

4.0

4.5

B (T)

Portable pulsed magnet
Capacitor bank: 533×658×1234mm3Max. 20T
Coil: outer diameter: 20-30mm, length: 10-30mm, bore size: 3-6mm

5.0

MM-wave
Pulseradiolysis

CTR(at sample position)
electron beam
10Lboptical delay
0～770ps for multi-bunch
For single-buncha new idea of layout is necessary.

(7.7ns)CTR

SummaryzKURRI-LINAC has been upgraded for coherent radiation.
stabilization, generation of single-bunch beam
zSeveral spectroscopic researches has been demonstrated.
Researches in progress
zOptical conductivity of superionic conductors(collaboration research with Tohoku Gakuin Univ.)
zOptical properties of waterand polymeric materials under γ-ray irradiation(collaboration research with Osaka Prefecture Univ.)
zDevelopment of pulseradilysis system