Positron annihilation spectroscopy using ultra-short pulsed laser Thomson scattered gamma-rays

Taira, Yoshitaka*; Fujimoto, Masaki*; Okano, Yasuaki*; Kitaura, Mamoru*; Hirade, Tetsuya  

Laser Thomson/Compton scattering is a unique technique to generate gamma-rays with features such as quasi-monochromatic and tunable energy, highly polarized, low divergence angle, and low background. We have developed GiPALS using an ultra-short pulsed gamma-ray generated at the synchrotron radiation facility UVSOR-III. The gamma-rays are generated via laser Thomson scattering with 90 degree collisions between a 750-MeV electron beam and a Ti:Sa laser. The pulse width of the gamma-rays is calculated to be 5 ps (FWHM). The gamma-ray induced positron annihilation lifetime spectroscopy (GiPALS) is currently available for users. In addition to GiPALS, we develop gamma-ray induced age-momentum correlation (GiAMOC), which measures the lifetime and Doppler broadening of annihilation gamma-rays simultaneously. In this conference, we will present a generation method of the ultra-short pulsed gamma-rays and details of GiPALS and GiAMOC.