Horst Märten, Dietmar Richter, Andreas Ruben, and Dieter Seeliger

Technische Universitat Dresden
Mommsenstrasse 13, DDR-8027 Dresden, G.D.R.

Waldemar Neubert

Central Institute for Nuclear Research, Rossendorf
PF 19, DDR-8051 Dresden, G.D.R.

Albert Lajtai

Central Research Institute for Physics, Budapest
POB 49, H-1525 Budapest, Hungary

The energy and angular distribution of prompt neutrons from 252-Cf spontaneous fission has been measured by the use of direction-sensitive fragment spectroscopy in conjunction with neutron time-of-flight spectroscopy. These data covering the whole angular range from 0° to 180° and the energy range from 100 keV to 10 MeV (18 MeV in polar direction) were the basis for the test of complex statistical-model approaches to prompt fission neutron emission.

Calculations have been performed in the framework of the cascade evaporation model (CEM) as well as the generalized Madland-Nix model (GMNM).

Using the parameter-free CEM several global methods for the description of optical potential and nuclear level density have been studied. The combination of the GMNM, whose free parameters were adjusted to reproduce the measured Cf data, with a simple scission point model including semi-empirical, temperature-dependent shell correction energies provide the basis for the consistent description of fragment energies (kinetic energy, excitation energy), prompt-neutron yields, energy and angular distributions of prompt fission neutrons as a function of mass asymmetry for any induced fission reaction in the Th-Cf region including the separate consideration of multiple-chance fission at high incidence energy.

KEYWORDS: fission reactions, neutron energy spectra, fission neutron multiplicity, statistical model, fission theory, nuclear data evaluation