CSR Workshop Sep.24, 2007, UVSOR Status of Coherent Radiation Beamline at KURRI-LINAC Toshiharu TAKAHASHI Research Reactor Institute, Kyoto University (Japan)
Outline � Outline of KURRI-LINAC � Specifications of the beamline (including coherence of CTR) � 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 ～ 4 µ s (Multi-bunch operation) Beam power: Max. 10kW (30MeV, 330 µ A) Peak current: Max. 8A Operation time: 2,700Hr (in 2006) Research field (collaboration research program) � Nuclear data with TOF � Isotope production � Electron irradiation � Coherent radiation since 1991 10 weeks user-time/year
Linac-based coherent radiation disadvantage Single-user advantages � High peak-power (the high amount of charge in a bunch ～ several nC) � Various types of coherent radiation are available. (synchrotron, transition, diffraction, Smith-Purcell, Cherenkov) � Interaction between electron beam and medium is available.
Schematic diagram of the beamline T i w i n d o w e l e c t r o n CSR is also available A l f o i l b e a m with a bending magnet. f r o m CTR CTR L - b a n d L i n a c spherical mirror A c c e l e r a t o r R o o m S h i e l d W a l l E x p e r i m e n t a l R o o m Parallel beam ( φ 15 cm) M o n o c h r o m a t o r I n t e r f e r o m e t e r spherical mirror
Photograph around the emission point (Target Room) Electron beam CTR flat Al-foil
Spectrometers and detectors � Martin-Puplett type broadband spectrum Interferometer (step scan) spectrometers ( home-made ) � Grating type monochromator monochromatic light (Czerny-Turner type) high dynamic range high sensitivity, low noise � Si bolometer VBW1kHz (Liquid-helium-cooled ) high sensitivity, low noise � InSb bolometer detectors VBW1MHz (Liquid-helium-cooled ) narrowband � Diode detector fast detector VBW1GHz � Lock-in amplifier signal acquisition for pulsed light source of � Fast gated integrator small duty ratio
Photograph of spectrometer Grating type monochromator (Czerny-Turner type) Martin-Puplett type (The grating is replaced by a flat mirror interferometer under the interferometer mode.)
Stability of intensity Pulse stability Long-time stability 0.02 VOLTAGE (V) within ± 1% 0.01 0 0 20 40 60 80 TIME (min.) Si bolometer on the interferogram Si bolometer on the interferogram Repetition rate: 46Hz Lock-in Amplifier (Time const.:0.1s) Oscilloscope: envelope mode
Correction of fluctuation Figure 3 Utilizati on of coherent .... T akahashi et al. If the intensity fluctuates due to (a)observed the trouble of the linac ….. 2.5 VOLTAGE interferogram 2.0 before 1.5 correction (b)beam current 1.5 CURRENT 1.0 0.5 3 (c)monitor VOLTAGE 2 1 (d)corrected 2.5 VOLTAGE interferogram 2.0 after 1.5 correction detector for monitoring fluctuation -4 -2 0 2 4 OPTICAL PA TH DIFFERENCE (cm)
Temporal structure of CTR Diode detector W-band 75-110GHz Macro-pulse width: 47ns enlarged 770ps (1.3GHz)
Interferogram of large optical path difference autocorrelation cross-correlation cross-correlation 0.04 AGE (V) OUTPUT VOLT 0.02 Inter-bunch distance 0cm 23cm 46cm 0 0 10 20 30 40 50 OPTICAL PATH DIFFERENCE (cm)
CTR form successive bunches 0.15 max.OPD=54.2cm high resolution ( ∆ν =0.018cm -1 ) INTENSITY (arb. units) max.OPD=5cm low resolution 0.10 -1 ) ( ∆ν =0.20cm 0.05 0.00 1 2 3 4 5 6 7 WAVENUMBER (cm -1 ) continuous spectrum ：Δν＞ f RF ／ c (cm -1 ) 0.043cm -1 for 1.3GHz Demerit of multi-bunch � Restriction on continuous spectrum The single bunch operation � Restriction on delay time is needed. in the time resolved measurement
Generation of single bunch Sub-harmonic pre-buncher High-speed avalanche-type pulser no space expensive Development and install on electron injector autocorrelation cross-correlation 0.2 0.15 OUTPUT VOLTAGE (V) 0.1 770ps degree of impurity ～ 1.5% 0.05 0 -10 -5 0 5 10 230 235 240 245 250 OPTICAL PATH DIFFERENCE (mm) Waveform of CTR （ diode detector ） Interferogram of CTR (Si bolometer)
Spectrum of CTR equipped on the interferometer (100W; aperture φ 10) (acceptance angle: 70mrad)
Pure rotational spectrum of N 2 O gas T.Takahashi et al. Rev.Sci.Instrum., 69(1998)3770 ENERGY (meV) 0.5 1 1.5 2 1 J=17 J=18 J=19 TRANSMISSIVITY J=2 J=3 J=4 J=5 J=6 J=7 J=8 J=20 J=9 J=10 J=11 J=12 J=13 J=15 J=14 J=16 0 5 10 15 WAVENUMBER (cm -1 ) Resolution: 0.2cm -1 Pressure: 2 × 10 4 Pa Optical path length in N 2 O: 9.3m
Absorption spectrum of OH - ion in NaCl (collaboration research with Tohoku Univ.) Cl NaCl(0.5mol%) t=5.7mm 4.22K 1.46K Na HO 10 ABSORPTION COEFFICIENT (cm -1 ) -1 (calc.) 1.56cm -1 (calc.) 1.88cm 8 6 4 2 -1 (exp.) 1.40cm -1 (exp.) 1.95cm 0 0 1 2 3 4 5 6 7 8 9 Light-pipe type VENUMBER (cm -1 ) WA 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 ions in RbMn 0.3 Mg 0.7 F 3 Repetition rate: 17 Hz Macro pulse ~ 4 µ s 1.2 CTR 77 K λ =2.5 mm 59 ms 1.0 Transmission 0.8 FWHM = 0.235 T B ~ 1 ms 0.6 Time delay 4.133 T 0.4 synchronization 2.0 2.5 3.0 3.5 4.0 4.5 5.0 B (T) Portable pulsed magnet Capacitor bank: 533 × 658 × 1234mm 3 Max. 20T Coil: outer diameter: 20-30mm, length: 10-30mm, bore size: 3-6mm
MM-wave Pulseradiolysis CTR (at sample position) electron beam 10 L b (7.7ns) optical delay 0 ～ 770ps for multi-bunch CTR For single-bunch a new idea of layout is necessary.
Summary � KURRI-LINAC has been upgraded for coherent radiation. stabilization, generation of single-bunch beam � Several spectroscopic researches has been demonstrated. Researches in progress � Optical conductivity of superionic conductors (collaboration research with Tohoku Gakuin Univ.) � Optical properties of water and polymeric materials under γ -ray irradiation (collaboration research with Osaka Prefecture Univ.) � Development of pulseradilysis system
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