Investigations of superheavy quasiatoms via spectroscopy of delta rays and positrons

This chapter discusses the use of high-energy electron rays and positrons to study quasi atoms. The high-energy tail of the electron-ray spectrum contains detailed information about the high-energy component of the momentum distribution of the bound electrons in the quasi atom. It is demonstrated that, at least in principle, the most direct way to investigate the question of the binding energy of very high Z systems is the spectroscopy of positrons, since a preionized diving level may decay by spontaneous positron emission. Topics considered include the spectroscopy of high-energy electron rays (general considerations, physical quantities, experimental arrangements, test of the basic concept, electron-ray spectroscopy in the high-Z /SUB u/ region), and the spectroscopy of positrons (positron creation in strong electric fields, physical quantities in positron spectroscopy, evaluation of atomic positrons). All the positron experiments described were performed for scattering systems in which the collison partners followed nearly pure Rutherford trajectories