Author: Katoh, M.
Paper Title Page
Laser-induced CSR: Toward a Probe to Explore Wakefields in Storage Rings  
  • S. Bielawski, C. Evain, E. Roussel, C. Szwaj, T. Tanikawa
    PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France
  • M. Adachi, M. Katoh
    UVSOR, Okazaki, Japan
  • M. Hosaka, N. Yamamoto
    Nagoya University, Nagoya, Japan
  • M. Le Parquier
    CERLA, Villeneuve d'Ascq, France
  • H. Zen
    Kyoto University, Institute for Advanced Energy, Kyoto, Japan
  In a storage ring, it is possible to imprint a sine modulation in the longitudinal phase space of an electron bunch, using interaction with an external laser. This typically leads to narrowband THz emission, as has been demonstrated at UVSOR-II*. This opens a new way to explore the dynamics of electrons bunches, by monitoring the transient following the sine perturbation. Here, we perform this type of experimental study at UVSOR, just below the CSR instability threshold. Then we perform corresponding numerical calculations using a Vlasov-Fokker-Planck modeling, including CSR wakefield. The data provided by these "laser manipulation experiments" are dependent on the wakefields, for some ranges of the excited wavenumber. Hence these laser experiments provide a new tool for testing dynamical models of storage rings, as CSR instability models.
* C. Evain et al., Phys. Rev. ST Accel. Beams 13, 090703 (2010); S. Bielawski et al., Nature Physics 4, 390 (2008).
slides icon Slides MOOBB02 [2.923 MB]  
THPPR057 Feasibility Study Gamma-induced Positron Annihilation Lifetime Spectroscopy in an Electron Storage Ring 4103
  • Y. Taira, H. Toyokawa
    AIST, Ibaraki, Japan
  • M. Adachi, M. Katoh, S. Tanaka
    UVSOR, Okazaki, Japan
  • N. Yamamoto
    Nagoya University, Nagoya, Japan
  Funding: This work was supported by Grants-in-Aid for Scientific Research (22360297) and Grant-in-Aid for JSPS Fellows (235193).
Positron annihilation lifetime spectroscopy (PALS) has proved to be very sensitive tool to characterize materials and study defects. However PALS has been restricted to thin samples because of the limited range of positrons in materials. We have developed new techniques for PALS, in which laser Compton scattered (LCS) gamma rays are used to produce positrons inside materials via pair production. Ultra-short gamma ray pulse source* with pulse width of 5 ps (FWHM) generated by 90-degree collision LCS was applied to PALS for the first time. The short pulse width of the gamma-rays that is negligible compared to estimated positron lifetime (100 ps to ns range) is essential to PALS. The experiment was carried out at the UVSOR-II electron storage ring, a 750 MeV synchrotron light source. The positron annihilation lifetime, 199 ± 10 ps, in a bulk sample of lead was successfully measured by using the ultra-short gamma ray pulse.
* Y. Taira, et al., Nucl. Instr. And Meth. A 637 (2011) S116.