  An attempt to unfold the respective influence of the fusion and fission
stages on typical fission observables, and namely the neutron pre-scission
multiplicity, is proposed. A four-dimensional dynamical stochastic Langevin
model is used to calculate the decay by fission of excited compound nuclei
produced in a wide set of heavy-ion collisions. The comparison of the results
from such a calculation and experimental data is discussed, guided by
predictions of the dynamical deterministic HICOL code for the compound-nucleus
formation time. While the dependence of the latter on the entrance-channel
properties can straigthforwardly explain some observations, a complex interplay
between the various parameters of the reaction can occur in other cases. A
multi-dimensional analysis of the respective role of these parameters,
including entrance-channel asymmetry, bombarding energy, compound-nucleus
fissility, angular momentum and excitation energy, is proposed. It is shown
that, depending on the size of the system, apparent unconsistencies may be
deduced when projecting onto specific ordering parameters. The work suggests
the possibility of delicate compensation effects in governing the measured
fission observables, thereby highlighting the necessity of a multi-dimensional
discussion.
