LEBRA, Funabashi, Japan
KEK, Ibaraki, Japan
Development of a cryogenic C-band photocathode RF gun cavity has been conducted at Nihon University in collaboration with KEK. Improved dimensions of the RF input coupler and the 2.6-cell accelerating structure from the first cold model were determined using the 3D simulation code CST Studio. The high-purity copper cavity was fabricated at KEK with ultraprecision machining and diffusion bonding technique. The low level RF properties of the cavity measured at room temperature have been in good agreement with the predictions based on the CST Studio calculation. Preparations for the 20-K cooling tests of the cavity are underway in KEK and Nihon University. The design of the improved cavity and the results of the cold test at low temperature will be discussed.
KEK, Ibaraki, Japan
The University of Tokyo, Tokyo, Japan
The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
Since a laser-driven dielectric accelerator (LDA) is most likely to deliver a nano-beam with a small scale device, a combination of the LDA and a biological cell observation device such as a fluorescence microscope seems to be a powerful tool for radiation biology researches. The LDA consists of single or a pair of binary-blazed transmission grating. In case of normal incidence, a grating constant must be the same with a laser wavelength to synchronize with the electron and an acceleration field. Although demonstration experiments have been published from SLAC and MPQ, there are many problems to be solved, especially in the non-relativistic energy region. A crucial problem is to make it clear whether electrons are accelerated with negligibly small wiggling or lateral shift. We are simulating at various conditions with the aid of CST-code. We also analyze an oblique incidence (OI) scheme for the efficient acceleration of slow electron. The OI-scheme enables to use the grating of larger grating constant. Adoption of the large grating constant makes it easy to fabricate the grating. Besides analytical works, we are making gratings and developing an Yb-doped fiber laser for the acceleration experiment. Gratings of two different materials, a glass silica and crystal silica, were fabricated by the e-beam lithography technique.
KEK, Ibaraki, Japan
JAEA, Ibaraki-ken, Japan
RLNR, Tokyo, Japan
JAEA/J-PARC, Tokai-mura, Japan
Kyoto ICR, Uji, Kyoto, Japan
NIRS, Chiba-shi, Japan
University of Tokyo, Tokyo, Japan
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
