Study of nuclei by charged photo-pion production

The π-meson has recently come in wider use in research on atomic nuclei, making use of the fact that π-mesons interact with nucleons in a way different from the nucleon-nucleon interaction. Unique features of the interaction accompanying the production of photo-π mesons from nuclei can also be very helpful for nuclear research. The present report outlines some features of research on the spin-isospin reverse transition between nuclear levels in the course of this reaction. It also describes some studies on slightly excited state of 12C, studies on special nuclear structures of 13C and 14N, and studies on highly excited states of 6Li. Some features of the gamma ray absorption by nuclei and particle release from nuclei are briefly outlined. The mechanism of the production of photo-π mesons from nuclei is described focusing on the elementary processes, photo-production of charged π mesons from nuclei, and semi-free process as background. Transformation of nuclei accompanying the photo-π meson production is discussed focusing on the features of the transformation, and difference from other nuclear reactions. Some studies on discrete states are also outlined. (N.K.)