Search

Atomic nucleus is a quantum many-body system consisting of protons and neutrons. Nevertheless, it is known that their characteristics can be well described and understood by the few-body picture. One of such pictures is the single-particle motion of a nucleon in a mean-field potential made by all nucleons. Another one is the clustering phenomenon, α clustering for example, in which a nucleus is divided into two or more clusters coupling weakly like molecules.One of the powerful probes for such states of a nucleus is the nucleon and cluster knockout reactions. In this paper, the distorted wave impulse approximation (DWIA) framework is briefly reviewed as one of the reaction theories which describes the knockout reaction. Its benchmark comparison with other reaction theories is also discussed. The application of the DWIA framework to the nucleon knockout reaction analysis from medium-mass neutron-rich nuclei driven by the RIKEN SEASTAR project is shown. As for the α knockout reaction, recent progress in reproduction of the α knockout reaction data from 20 Ne is reviewed and the surface sensitivity of the reaction is discussed. The first direct evidence of the α particle formation on the surface of medium mass nuclei and its isotope dependence is also introduced. Finally, the summary and perspectives of the particle knockout reactions are given. [ABSTRACT FROM AUTHOR]