• S. Hirata
  Hiroshima University, Faculty of Science, Higashi-Hirosima
• S. Sasaki
  HSRC, Higashi-Hiroshima

Different form conventional periodic undulators, the quasi-periodic undulator (QPU) can radiate　irrational harmonics instead of rational harmonics. It suits with experiments that need highly monochromatic light after passing through the monochromator. For this reason, the QPU is used in many synchrotron radiation facilities all over the world. Recently, new type QPUs that generate radiation spectra different from those by conventional type QPU were proposed*,**. In principle, the shape of radiation spectrum from a new QPU is determined by magnetic field distribution having different quasi periodic pattern. However, calculated spectra using a realistic magnetic field are often different from those of theoretical expectation. In this paper, a detailed comparative study is conducted to examine why there are these differences, how to correct magnetic field to get predicted spectra that fit to the theory. In addition, a possibility of modifying the basis of theory is investigated. These results, new generation method of new quasi-periodicity, and magnetic field distribution to achieve the best performance are presented at the conference.

* S. Sasaki, Proceedings of PAC09, Vancouver, May, 2009.
** S. Sasaki, Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (in Japanese).

• G. Isoyama, M. Fujimoto, K. Furuhashi, S. Kashiwagi, R. Kato, M. Morio, J. Shen, S. Suemine, N. Sugimoto, Y. Terasawa
  ISIR, Osaka
• S. Hirata
  Hiroshima University, Faculty of Science, Higashi-Hirosima

The 40 MeV L-band electron linac at the Institute of Scientific and Industrial Research, Osaka University is extensively used for various applications on advanced beam sciences including radiation chemistry by means of pulse radiolysis and development of the free electron laser in the THz region. It was constructed in 1975-78 and has been remodeled sometimes for improving its performance. The most recent one was made in 2002-2004 for higher operational stability and reproducibility, resulting in significant advances in the studies. We will report the present status of the linac and results of its performance evaluation.