• H.H. Lee, K. Min
  KAIST, Daejeon
• Y.U. Jeong, K. Lee, S. H. Park
  KAERI, Daejon
• H. Seo
  Hanyang University, Seoul
• H. Shim
  Korea University, Seoul

Laser accelerated electron beam can be a compact source for high energetic photon generation for nuclear application. A simulation code using GEANT4 has been developed for the estimation of Bremsstrahlung radiation from laser accelerated electron beams impinging on a metalic target and the photonuclear reaction of a sample target. It includes ElectroMagnetic physics , Photonuclear reaction and Radio Active Decay physics, so that the calculation from Bremsstrahlung radiation to decay process can be conveyed in series. The energy and angular distribution of Bremsstrahlung radiation depending on different target thickness and electron parameters as well as the emission spectrum by radioactive decay due to photonuclear reaction can give us an idea of optimal condition for the desired nuclear applications. We discussed the critical issues of high energy photon generation for photonuclear reaction experiments.

• H. Tomizawa, H. Dewa, H. Hanaki, S. Matsubara, A. Mizuno, T. Taniuchi, K. Yanagida
  JASRI/SPring-8, Hyogo-ken
• T. Ishikawa, N. Kumagai
  RIKEN/SPring-8, Hyogo
• K. Lee
  University of Tokyo, Tokyo
• A. Maekawa, M. Uesaka
  UTNL, Ibaraki

We developed a single-shot and non-destructive 3D bunch charge distribution (BCD) monitor based on Electro-Optical (EO) sampling with a manner of spectral decoding for XFEL/SPring-8. For the transverse detection, eight EO-crystals (Pockels effect) surround the beam axis azimuthally, and a linear-chirped probe laser pulse with a hollow shape passes through the EO-crystal. We plan to use an amorphous material which has only an even-order field dependence (Kerr effect) in donut shape without assembling eight conventional EO-crystals. The polarization axis of the probe laser should be radially distributed as well as the Coulomb field of the electron bunches. Since the signal intensity encoded at each crystal depends on the strength of the Coulomb field at each point, we can detect the transverse BCD. In the longitudinal detection, we use a prove laser with a broadband square spectrum (> 400 nm @ 800 nm) so that the temporal resolution is < 30 fs, if the pulse width of probe laser is 500 fs. In order to achieve 30-fs temporal resolution, we use an organic EO material, DAST crystal, which is transparent up to 30 THz. We report the first experimental results of our 3D-BCD monitor.