• H. Hama, F. Hinode, S. Kashiwagi, M. Kawai, F. Miyahara, T. Muto, K. Nanbu, Y. Tanaka
  Tohoku University, School of Scinece, Sendai

The t-ACTS (test Accelerator as Coherent THz Source) at Tohoku University will provide intense terahertz radiation employing novel sources such as an isochronous accumulator ring and a pre-bunched free electron laser. Stable production of the very short electron pulse is a key issue for the t-ACTS accelerator system, in which a thermionic RF gun is being used. Particularly observation of the longitudinal phase space of the beam extracted the gun is crucial for efficient bunch compression. Because of space charge effect, the beam has to be diagnosed within a short drift space. We have studied a novel energy spectrometer using Cherenkov radiation (Linear Focal Cherenkov ring camera, LFC-camera). Though the method is valid for the lower energy less than 3 MeV, the energy distribution can be measured immediately at the gun exit. In addition to the present status of the t-ACTS project, we describe the principle of LFC camera and discuss energy resolution, prospect of the direct measurement of the particle distribution in the longitudinal phase space as well.