• N. Hayashizaki
  RLNR, Tokyo
• R. Kuroda, B.E. O'Rourke, N. Oshima, R. Suzuki
  AIST, Tsukuba, Ibaraki
• E.J. Minehara
  WERC, Tsuruga , Fukui

Positron that is the antiparticle of the electron, by the specific character, can evaluate vacant spaces in microstructure from atomic level to nanometer level, which is difficult in other measurement methods. In the case of high functional material, this structure often relates directly to the performance, and the evaluation method that uses the positron beam is expected as a useful measurement tool to develop a new material. If it is able to produce more high-intense and low-energy positron beam with an accelerator, the microstructure evaluation is carried out in prompt and high accuracy for various demands of the material analysis. We have studied a positron production system using a superconducting electron linac instead of normal conducting one. Electron beam accelerated with the superconducting linac is irradiated on tantalum and converted to bremstrahlung photons, and positron beam is produced by pair creation of them. The designed acceleration energy of the superconducting electron linac is 15-40 MeV and the maximum beam power is 10 kW. The system configuration and the progress status will be presented.

• Y. Hosaka, R. Betto, A. Fujita, K. Sakaue, M. Washio
  RISE, Tokyo
• S. Kashiwagi
  ISIR, Osaka
• R. Kuroda
  AIST, Tsukuba, Ibaraki
• K. Ushida
  RIKEN, Saitama

We have been studying a pump-probe pulse radiolysis as an application of the S-band photo cathode RF-Gun. Pump-probe spectroscopy is well-known method of pulse radiolysis measurement. We had used 5MeV electron beam obtained from the photo cathode RF-Gun as a pump beam, and used the white light emitted from Xe flash lamp or generated by self-phase modulation in the water cell as a probe light. However, the white probe light with high intensity, good stability and broad spectrum is a key issue for pump-probe pulse radiolysis. Supercontinuum light with photonic crystal fiber (PCF) is a new technique of white light generation. Short pulse laser through PCF spreads its spectrum by nonlinear optical effect. Supercontinuum light has very continuous spectrum, and it is studied for various applications recently. For applying supercontinuum light as a probe of pulse radiolysis experiment, we have generated a supercontinuum radiation with 7 picoseconds pulse width IR (1064nm) laser and PCF, and measured its properties. The experimental results of supercontinuum generation and design of a supercontinuum based pulse radiolysis system will be presented.

• R. Kuroda, H. Ikeura-Sekiguchi, M. Koike, H. Ogawa, N. Sei, H. Toyokawa, K. Yamada, M.Y. Yasumoto
  AIST, Tsukuba, Ibaraki

Advanced quantum radiation sources such as a laser Compton scattering X-ray source and a coherent THz radiation source have been developed based on an S-band compact electron linac at AIST in Japan. The laser Compton scattering X-ray source using a TW Ti:Sa laser can generate a hard X-ray pulse which has variable energy of 12 keV - 40 keV with narrow bandwidth by changing electron energy and collision angle for medical and biological applications. The coherent THz radiation source based on the electron linac has been also developed instead of a conventional laser based THz source. The designed THz pulse has high peak power more than 1 kW in frequency range between 0.1 - 2 THz. The THz pulse will be generated with coherent radiation such as synchrotron radiation and transition radiation using an ultra-short electron bunch with bunch length of less than 0.5 ps (rms). The coherent synchrotron radiation in the THz region has been already generated and it will be applied to the THz time domain spectroscopy (TDS). In this work shop, we will report present status of our advanced quantum radiation sources.

• Y. Yokoyama, T. Aoki, K. Sakaue, T. Suzuki, M. Washio, J. Yokose
  RISE, Tokyo
• H. Hayano, N. Terunuma, J. Urakawa
  KEK, Ibaraki
• S. Kashiwagi
  ISIR, Osaka
• R. Kuroda
  AIST, Tsukuba, Ibaraki

At Waseda University, we have been studying a high quality electron beam generation and its application experiments with Cs-Te photocathode RF-Gun. We have already succeeded in generating a stable high-charged single-bunch electron beam. To generate more intense electron beam, we designed a multi-bunch electron linac and developed the multi-pulse UV laser which irradiates to the cathode. The target values of the number of electron bunch and bunch charges are 100 bunches/train and 800 pC/bunch, respectively. In addition, we adopted the method of the amplitude modulation of the incident RF pulse to the S-band klystron in order to compensate the energy difference in each bunch because of the slow rise time of acceleration voltage in cavity and beam loading effect in the accelerating structure. In this conference, we will report design properties of our multi-bunch electron linac, the results of the multi-bunch electron beam diagnosis and the energy difference compensation using the RF amplitude modulation method.