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Uesaka, M.

Paper Title Page
THPMN033 Commissioning a Cartridge-Type Photocathode RF Gun System at University of Tokyo 2787
  • A. Sakumi
    UTNL, Ibaraki
  • Y. Muroya, T. Ueda, M. Uesaka
    The University of Tokyo, Nuclear Professional School, Ibaraki-ken
  We have been developing a compact-sized cartridge-type cathode exchanging system installed in BNL-type IV photocathode RF gun. We can replace a cathode without breaking the vacuum of RF gun, so that a high quantum efficiency photocathode is not surrounded by oxygen or moisture. The advantage of this system can be controlled the quality of the each cathode by making cathode plugs in a factory. Moreover we can easily change a cathode material, such as visible light driven cathode (AgOCs NaK2Sb) the high QE cathode(Cs2Te) for high brightness beam, metal cathode(Mg) for ultra-fast phenomena. Therefore we can investigate characterization of variable cathode materials in high gradient electric field of ~100MV/m. The cavity with the exchanging port and the beam trajectory is calculated by superfish and GPT, respectively. We found that the parameters of the cavity with a plug is almost same compared with normal back plate. Using this system, we can investigate the cathode material and deliver the stable electron beam by one RF gun.  
THPMN035 Pinpoint keV/MeV X-ray Sources for X-ray Drug Delivery System 2793
  • M. Uesaka, F. Sakamoto, A. Sakumi
    The University of Tokyo, Nuclear Professional School, Ibaraki-ken
  X-ray Drug Delivery System (DDS) is the most advanced radiation therapy coming after IMRT (Intensity Modulated Radiation Therapy) and IGRT (Image Guided). DDS uses advanced nano-scaled polymers which contain and deliver drug or contrast agent to cancers without side effects. Several X-ray DDS poses high-Z atoms like Pt and Au to absorb X-rays effectively and used as contrast agent for inspection. Moreover, they have radiation enhancement effect by emission of Auger electron and successive characteristic X-rays. The enhancement factor off Pt and Au is more than five. This can be used for therapy. This new modality must be very important for inspection and therapy of deep cancers. We are making use of our Compton scattering monochromatic keV X-ray source and MeV linac aspinpoint keV/MeV X-ray sources for the purpose. Physical analysis and evaluation of the contrast efficiency and radiation enhancement of the X-ray DDS are under way. Furthermore, a new compact X-band linac with a multi-beam klystron for a pinpoint X-ray source is proposed and designed. Updated research status and result are presented.  
THPMN034 Manipulation of Electron Beam Generation with Modified Magnetic Circuit on Laser-wakefield Acceleration 2790
  • A. Yamazaki, T. Hosokai, K. Kinoshita, A. Maekawa, R. Tsujii, M. Uesaka, A. G. Zhidkov
    UTNL, Ibaraki
  Electron beam injection triggered by intense ultrashort laser pulses, which is called as plasma cathode, is presented. We have studied generation of relativistic electrons by interaction between a high intensity ultra-short laser pulse and gas jet. When a static magnetic field of 0.2 T is applied, the modification of the preplasma cavity, and significant enhancement of emittance and an increase of the total charge of electron beams produced by a 12 TW, 40 fs laser pulse tightly focused in a He gas jet, were observed. And very high stability and reproducibility of the characteristics and position of well-collimated electron beams was detected. Now we are planning to experiment with a magnetic circuit that has more intense magnetic field of 1 T. The present report aims at presenting these experimental and analytical results.  
THPMN031 Experiment of X-Ray Source by 9.4 GHz X-Band Linac for Nondestractive Testing System 2781
  • T. Natsui, K. Dobashi, M. Uesaka, T. Yamamoto
    UTNL, Ibaraki
  • M. Akemoto, S. Fukuda, T. Higo, N. Kudoh, T. T. Takatomi, M. Yoshida
    KEK, Ibaraki
  • F. Sakamoto, A. Sakumi
    The University of Tokyo, Nuclear Professional School, Ibaraki-ken
  • E. Tanabe
    AET Japan, Inc., Kawasaki-City
  We are developing a compact X-ray source for Nondestractive Testing (NDT) system. We aim to develop a portable X-ray NDT system by 950 keV X-band linac to realize in-site inspection. Our system has 20 kV electron gun, and accelerate electron beam to 950 keV with 9.4 GHz X-band linac. RF source of this system is 250kW magnetron. Our target spot size and spatial resolution are 1mm. We adopted APS (Alternative Periodic Structure) tube of pi/2 mode for easy manufacturing. It is difficult to realize a high-shunt-impedance for low-energy-cells, which attributes to manufacturing problems. Instead, we use three pi-mode cavities there. Further, we choose the low power magnetron for small cooling system and the low voltage electron gun for small power supply. For the stability of the X-ray yield the system include the Auto Frequency Control (AFC), which detect and tune the frequency shift at the magnetron. We have also performed X-ray generation calculation by the Monte Carlo code of GEANT and EGS to confirm the X-ray source size. We are going to construct the whole system and verify it experimentally. Updated results are presented at the spot.  
THPMN032 Beam Generation and Acceleration Experiments of X-Band Linac and Monochromatic keV X-Ray Source of the University of Tokyo 2784
  • F. Sakamoto, T. Natsui, Y. Taniguchi, M. Uesaka, T. Yamamoto
    UTNL, Ibaraki
  • M. Akemoto, T. Higo, J. Urakawa
    KEK, Ibaraki
  • D. Ishida, N. Kaneko, H. Nose, H. Sakae, Y. Sakai
    IHI/Yokohama, Kanagawa
  • M. Yamamoto
    Akita National College of Technology, Akita
  In the Nuclear Professional School, the University of Tokyo, we are constructing an X-band linear accelerator that consists of an X-band thermionic cathode RF gun and X-band accelerating structure. This system is considered for a compact inverse Compton scattering monochromatic X-ray source for the medical application. The injector of this system consists of the 3.5-cell coaxial RF feed coupler type X-band thermionic cathode RF gun and an alpha-magnet. The X-band accelerating structure is round detuned structure (RDS) type that developed for the future linear collider are fully adopted. So far, we have constructed the whole RF system and beam line for the X-band linac and achieved 2 MeV electron beam generation from the X-band thermionic cathode RF gun. In addition, we achieved 40 MW RF feeding to the accelerating structure. The laser system for the X-ray generation via Compton scattering was also constructed and evaluated its properties. In this presentation, we will present the details of our system and progress of beam acceleration experiment and the performance of the laser system for the Compton scattering experiment.  
FRPMN044 Measurement of Ultra-short Electron Bunch Duration by Coherent Radiation Analysis in Laser Plasma Catode 4066
  • R. Tsujii, K. Kinoshita, Y. Kondo, A. Maekawa, Y. Shibata, M. Uesaka, A. Yamazaki
    UTNL, Ibaraki
  • T. Hosokai
    RLNR, Tokyo
  • T. Takahashi
    KURRI, Osaka
  • A. G. Zhidkov
    Central Research Institute of Electric Power Industry, Komae
  Laser plasma accelerator can recently generate monochromatic and low-emittanced electron bunchs. Its pulse duration is femtoseconds, 40fs by the PIC simulation and about 250fs by measurement at University of Tokyo. But in such measurements only time-averaged spectrum and pulse duration were obtained by a few bolometers and coherent transition radiation (CTR) interferometer. Since the electron generation and acceleration are not stable yet, we need to know shot-by-shot behavior to improve its mechanism. Here we introduce the polychromator with ten channel-sensors for the single shot measurement. By this polychromator, we can obtain such a discrete spectrum of CTR by a single shot, thus the bunch duration can also be obtained shot-by-shot. This polychromator has ten channels to observe infrared radiation, and is mainly sensitive for the wavelengths around 1~2mm. We select this range of wavelength as the measurement tool, because the electron bunch duration changes shot-by-shot during traveling along the distance between the plasma and Ti foil (CTR emitter) due to their energy spectrum fluctuation. Further results and discussion will be presented on the spot.