• Y. Kitagawa, K. Fujita, R. Hanayama, K. Ishii, Y. Mori
  GPI, Hamamatsu
• T. Kawashima
  Hamamatsu Photonics K.K., Hamamatsu
• H. Kuwabara
  IHI, Yokohama

A technique for remote detection of hidden objects is an urgent issue, but is not yet realized, because a source and a sensor must be located on the same side of the object. An ultra-intense laser can produce extremely short and directional radiations, that is the inverse Compton scatterings used for the backscattering system. We here demonstrate that the laser-wakefiled-accelerated 10-MeV electrons inversely scatter the same laser light to keV X-ray emissions. A 10 TW OPCPA Ti:sapphire laser BEAT ( 1J output, wavelength 815 nm, and pulse width 150fs) is divided to two beams. A 0. 8-J beam is focused to an entrance edge of helium gasjet to accelerate electrons via wakefield and the other 0.2-J beam is focused to the exit of the plasma channel from the opposite direction. A second harmonic probe light measured the channel density. To the upstream direction of the latter beam, a CdTe detector analyzed the Compton spectrum under a photon counting mode* in the range of 1 keV to 20 keV, which well agrees with that calculated from the obtained electron spectrum up to a few tens MeV. We also have observed that the emission is strong into the laser axis direction.

*H. Kuwabara, Y. Mori, Y. Kitagawa, 'Coincident Measurement of a Weakly Backscattered X-ray with a CPA Laser-Produced X-ray Pulse', Plasma Fusion Research: 3, 003-004 (2008).

• T. Fujinaka, T. Matsunaga, S. Mochizuki, H. Takase
  Kyushu University, Center for Accelerator and Beam Applied Science, Fukuoka
• H. Arima, T. Hasuo, N. Ikeda, K. Ishibashi, T. Korenaga, K. Maehata, N. Shigyo, Y. Uozumi, G. Wakabayashi, Y. Yonemura
  Kyushu University, Department of Applied Quantum Physics and Nuclear Engineering, Fukuoka
• K. Fujita, T. Morikawa, T. Noro, T. Wakasa
  Kyushu University, Fukuoka
• Y. Mori
  KURRI, Osaka
• H. Nakayama, A. Takagi
  KEK, Ibaraki
• T. Tomimasu
  SAGA, Tosu

150 MeV FFAG accelerator is under construction at Center for Accelerator and Beam Applied Science on Ito Campus to promote activities in all related scientific, medical, engineering and educational field at Kyushu University. In this paper, status of the development of hardware and the results of the beam commissioning of the injector are described.