CO11-1

Coherent Terahertz Spectroscopy of Bile Acids by L-Band LINAC

M. Kawase, T. Saito1, T. Takahashi2 and K. Takahashi3,4

REFERENCES:

Faculty of Bioscience, Nagahama Institute of Bio-scienceand Technology
1Radioisotope Research Center, Osaka University
2
Kyoto University Research Reactor Institute3
Graduate School of Pharmaceutical Sciences, Osaka
University
4Museum, Osaka University[1] T. Takahashi, T. Matsuyama, K. Kobayashi,
and Y. Fujita,Utilization of coherent transition radiation from a linear accelerator as asource of millimeter-wave spectroscopy. Rev.
Sci. Instr., 69(1998) 3770-3775.
[2] T. Takahashi, Coherent synchrotron radiation. Kasokuki 2(2005) 11-19 (in Japanese).

THz time domain spectroscopy(THz-TDS) using THz pulses generated by femtosecond laser is the mainly used method in THz spectroscopy. Moreover, coherent THz wave [1,2]recently attracts the attentions by the development of free electron laser. Although coherent THz wave is also the useful, the study
about an application of coherent THz wave
hardly develops. In this study, we examinedthe characteristics and usefulness of coherent
THz wave, and applied it to the analysis ofnatural materials, bile acids.
INTRODUCTION:EXPERIMENTS: Coherent THz wave was ob-

tained from the transition radiation generatedby L-band linear accelerator in Kyoto University Research Reactor Institute. The absorption
spectra were measured as time-domain signalby the composite type liquid-helium-cooledsilicon bolometers after through Martin-Puplett
type interferometer and sample. By Fouriertransforming the time-domain signal, the amplitude spectra were obtained.
Bile acids are one group of theimportant natural compounds, relating toprocessing of dietary fat. THz spectra of somekinds of bile acids were measured by using coherent THz wave. The spectra were remarkably different between sodium salt and sodium
free form of cholic acid as shown in Figs. 1 and2. Mid-infrared spectroscopy suggested thatthe peaks in the dashed circles are the vibration mode of C=O group. Such peak shift in sodium salt was observed in the THz spectra ofdeoxycholic acid. We, now, try to explain thereason of the peak shift effect of sodium in THz
spectra by quantum chemical calculations.

Fig. 1.

THz spectrum of cholic acid (sodium free form)

RESULTS:

Fig. 2. THz spectrum of sodium cholate (sodium salt)

採択課題番号 23001
L-バンド LINAC を用いた胆汁酸の THｚ分光
共同通常（長浜バイオ大）川瀬雅也、（阪大・RI センター）斎藤 直、（京大炉）高橋俊晴（阪大院・薬、阪大博物館）高橋京子

CO11-2

Evaluation and Verification of Photon Irradiation Field at KURRI-LINAC

T. Kubota, T. Ohta1 and Y. Mahara

EXPERIMENTS: The foil activation was conductedwith high-energy photons produced by electron irradiation of lead sheets water-cooled in an aluminum container.
A gold foil was placed behind the lead sheets in the electron beam line and irradiated with changing sheet thickness ranging from 1 to 32 mm. The energy spectrum ofincident photon beam into the gold foil was simulated byElectron Gamma Shower (EGS5) Monte Carlo code.
Both results of gold foil activation and EGS5 can beconnected with activation equation. The activation equation, if irradiation time is sufficient short, can be expressed asA= σ ( E ) ⋅ ϕ g ( E )dE
N λ ti ⋅ ne ∫where A, λ, and σ are produced activity, the decay constant and the production cross-section of Au-196, respectively, and N, ti, ne and ϕg are the number of gold atom,irradiation time, the number of incident electron and theflux of photon per electron irradiated, respectively. The
number of incident electron (ne) can be obtained by multiplying 6.24x1018 to average electron beam current. The
value of the left and right member of the equation wereobtained from results of Au foil activation and EGS5,
respectively and defined here as activation rate.
RESULTS: The bremsstrahlung energy spectra simulated by EGS5 show continuous spectra and their flux isdecreased with energy (Fig.1). The most effective photon
production was obtained at the lead thickness of 2 mm.
Fig.2 shows the cross-section of Au-197 (γ, n) Au-196 [3]averaged in each energy bin used in EGS5. Fig.3 shows
activation rate from the EGS5 simulation and the gold
foil activation. Both values agreed well with each otherfor lead thickness more than 8 mm. Further study is required to elucidate discrepancies for thinner lead sheets.

particles/MeV/source particle

Pb 1 mm
Pb 2 mm0.004

Pb 5 mm
Pb 10 mm0.003Pb 20 mm0.002
0.001
05101520Energy / MeV

2530

Fig.1. Bremsstrahlung spectra generated by 30
MeV electrons
600cross-section / mb

INTRODUCTION: At the KURRI-LINAC, the acceleration energy of electrons can be varied from 6 to 46
MeV by regulation of microwave power [1-2]. Thus theflexibility of bremsstrahlung irradiation has increased.
The spectrum of bremsstrahlung has been investigated bycomparing results from Monte Carlo simulation and foilactivation.

500
400300200
100081012141618Energy / MeVFig.2. Average cross-section of photonuclear reaction from Au-197 to Au-196
Activation Rate / (1E-27)

Research Reactor Institute, Kyoto University
1Graduate School of Engineering, Hokkaido University

0.005

4EGS
Au-foil

32100

102030405060

Pb thickness / mm

Fig.3. Comparison of activation rate evaluatedfrom EGS5 and foil activation
REFERENCES:[1] T. Kubota et al., KURRI Progress Report, 2008(2009) 189.
[2] T. Kubota et al., Proc. LINAC10 (2010) 67[3] B. L. Berman, Atomic Data and Nuclear Data Tables
15 (1975) 319-390

採択課題番号 23004光子照射による汚染土壌の回復の検討（京大・原子炉）窪田卓見、太田朋子、馬原保典

౒หㅢᏱCO11-3 Developmentsof Coherent Synchrotron Radiations for Terahertz-wave
Spectrophotometry by Compton Backscattering Using KURRI-LINAC

N. Sei and T. Takahashi1
Research Institute of Instrumentation Frontier, National
Institute of Advanced Industrial Science and Technology
1
Research Reactor Institute, Kyoto University
INTRODUCTION: We have studied terahertz-wave
spectrophotometrybyCompton
backscattering(THz-SCB) using an L-band electron linear accelerator at
the Kyoto University Research Reactor Institute(KURRI-LINAC) [1, 2]. When a coherent synchrotron
radiation is used as a light source of the THz-SCB, theenergy of the synchrotron radiation is much lower thanthat of the Compton backscattered photons. Then, wedeveloped coherent synchrotron radiations with a pair ofbending magnets comprised of permanent magnets. Yieldof the Compton backscattered photon increases as across-section of an electron beam becomes small. We
also conducted measurements of electron-beamemittances by a Q-scan method with using new
quadrupole magnets, which installed in theKURRI-LINAC.
EXPERIMENTS: We used two bending magnets comprised of permanent magnets, which has a gap of 40 mm
and magnetic field of 0.16 T. The length of the magnet
was 55 mm. Figure 1 shows a photograph which illustrates the location of the bending magnets. The electron
beam passes through the center of the bending magnets
from the left side in a vacuum chamber and is released in
the atmosphere. When a distance between the two bending magnets is set to be 295 mm, the electron beam withthe energy of 32 MeV moves to a distance of 40 mm inparallel. There is a magnetic-filed-free space between thebending magnets. A synchrotron radiation, which wasemitted on an axis of the electron-beam trajectory in thespace, was transformed to an experimental room. A spectrum of the synchrotron radiation from the bending magnets was measured by a Marin-Pupplett interferometerwith a high-sensitivity Si bolometer. We observed a coherent synchrotron radiation whose intensity was approximately one-thirtieth of intensity of the coherent
transition radiation developed in KURRI-LINAC. A
wavelength of a peak power of the coherent synchrotron
radiation was approximately 3 mm, so that it shifted inthe longer wavelength direction compared with that of
the coherent transition radiation. A wavelength at which aspectrum of the Compton backscattered photon had amaximum was calculated to be approximately 190 nm forthe electron-beam energy of 32 MeV. We should set it tobe 300 nm due to sensitivity of a detector for the Compton backscattered photon. Therefore, it was noted thatoptimum electron-beam energy for the THz-SCB in theKURRI-LINAC was approximately 25 MeV.

Fig. 1. Photograph of two bending magnets comprised ofpermanent magnets.

Recently, to focus the electron beam at an Al foil target in coherent transition radiation experiments, a doubletof quadrupole magnets was installed after the accelerator
tubes in the KURRI-LINAC. We measured the electron-beam emittances by a Q-scan method with using thenew quadrupole magnets. An Al board was set just after aTi window which located at the end of the linac. It inclined 45 degrees for electron beam. A transition radiation caused at the Al board was imaged at an optical fiber
on a two-dimension translation stage. The transition radiation was transported by the optical fiber to the experimental room, and its intensity was measured by a photomultiplier. Normalized emittance was calculated by theelectron-beam size while changing magnetic field of aquadrupole magnet. It was clarified that the normalized
emittance was 4.9710-4 mrad in the horizontal direction
and 3.5210-4 mrad in the vertical direction. Then, theelectron-beam size at a collision point of the Compton
backscattering will be less than 5 mm in THz-SCB experiments.
CONCLUSIONS: We achieved to develop a coherent
synchrotron radiation using two bending magnets comprised of permanent magnets. A spectrum of the coherent
synchrotron radiation was measured, and a wavelength of
its peak power was approximately 3 mm at the electron-beam energy of 32 MeV. It was found that the appropriate beam energy for THz-SCB experiments wasapproximately 25 MeV in the KURRI-LINAC. Moreover,
we measured an electron-beam emittance by a Q-scanmethod with using new quadrupole magnets. The electron-beam size at a collision point of the Compton
backscattering will be less than 5 mm in THz-SCB experiments. We will conduct THz-SCB experiments using
the developing coherent synchrotron radiation.
ACKNOWLEDGMENT:This work was supported
by JSPS Grant-in-Aid for Challenging Exploratory Research 2365696.
REFERENCES:[1] N. Sei et al., Appl. Phys. Exp., 1 (2008) 087003/1-3.
[2] T. Takahashi and K. Takami, Infrared Phys. Technol.,
51 (2008) 363-366.

採択課題番号 23069 コヒーレント放射を用いたテラヘルツ波電子線分光法の研究（産総研）清 紀弘（京大・原子炉）高橋 俊晴

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