since it might seem astonishing that resolving the 2-dimensional Langevin equation, where trajectories can fill out more effectively the deformation space (as it is demonstrated with the typical trajectory drawn on Fig. 5), would lead to shorter fission times than when the compound nucleus follows the deepest symmetric fission valley of the 1-dimensional picture. In fact we have to think of the Langevin equation as an approximation to the Fokker-Planck one which deals with probability distributions. In an 1-dimensional space the system is constrained whereas, the more the dimensionality is increased, the less constraints one has.\

FIG. 5. Temperature dependent LDM energy landscape and typical fission trajectory for the compound system $^{227}$Pa ($E^*_{tot} = 26$ MeV, $L = 60 \hbar$).

This result on fission times seems also to indicate that in the case of highly excited nuclei our previous 1-dimensional description was already fairly accurate. The small change in times should indeed imply a rather small change in pre-fission particle multiplicities.

### Influence of shell effects and pairing correlations

Let us now go one step further by including in our potential energy calculation quantal effects and their dependence on temperature. It is generally admitted that shell corrections have disappeared for 