Fission

Since fission corresponds to a typical large-scale motion process, it has been recognised as one of the most promising tools for deducing information on nuclear viscosity, and on shell effects and collective excitations at extreme deformation. This is not only important from the fundamental point of view but is of the prime interest in many challenging fields in nuclear physics, like e.g. super-heavy element synthesis or nuclide production in secondary-beam facilities. However, many questions still remain open, mainly due to the fact that experiments were restricted up to very recently to spontaneously fissioning isotopes and primordial or long-lived target nuclei. First-generation experiments performed at GSI have proven that the use of secondary beams indeed opens new prospects for studies of nuclear fission [1]. More than 100 short-lived neutron-deficient nuclei will become available for such investigations. It will be possible, for the first time, to identify both fission fragments in A and Z at different excitation energies. This information in combination with fission-fragment velocities would give new insight into the dynamics of the fission process. The full isotopic distribution of the fission fragments is a sensitive signature of the excitation energy at which fission occurs in the statistical deexcitation cascade. The knowledge of the emitted neutrons and γ radiation accompanying the fission process allows determining the excitation energies of the final products.

[1] K.-H. Schmidt et al., Nucl. Phys. A 665 (2000) 221.