The doorway to the continuum

The recent advance in the studies of the inclusive spectra from proton-induced reaction is described, particularly focusing on (p, 2p) reaction. The measured two-dimensional energy spectra for the 58Ni(p, 2p) reaction induced at 100 and 198 MeV were analysed in terms of the quasifree nucleon-nucleon (QFNN) process. The analysis suggested that the incident nucleons with energy between 100 and 200 MeV interacted with nuclei primarily via an initial QFNN process which acted as a ''doorway'' leading to the more complicated excitation resulting from the further interaction of one or both of the nucleons involved in the initial scattering. This process appears to be well-understood in terms of the multistep direct reaction formalism. Thus, the QFNN interaction can be viewed as the ''doorway to the continuum''. (Asami, T.)