New trends in nuclear research based on laser Compton scattering γ-ray beams

Laser Compton scattering (LCS) γ-ray has a number of advantages not found in other γ-ray sources, such as quasi-monochrome, variable energy, beam profile, and capability of linear (circular) polarization, and has been used in various fields including nuclear physics research. This paper discusses the development situation of the high-intensity LCS γ-ray source of new generation, as well as the possibility of photonuclear physics. The high-brightness LCS γ-ray source of new generation with the magnitude higher by 4-7 orders than the conventional LCS γ-ray was proposed, and its construction has already been started in Europe. The LCS γ-ray based on energy recovery linac (ERL) was proposed in Japan, too. KEK performed electron acceleration due to compact ERL for demonstrating the principle, and is generating the LCS γ-ray of approximately 7 keV, using a laser stacking cavity built into a compact ERL. As for the studies on photonuclear physics, the following items are reviewed: Studies on nuclear structure based on linearly polarized γ-ray, studies on supernova explosion based on photonuclear reaction, determination of the reaction cross-sectional area of ¹²C(α,γ)¹⁶O in nuclear astrophysics, photonuclear fission, parity non-conservation due to circularly polarized γ-ray, and Delbruck scattering as one of the nonlinear effect of QED. (A.O.)