compound nucleus $^{227}$Pa at an angular momentum of $L = 60 \hbar$.\

Evaluation of shell corrections close to the scission point
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In the framework of the Strutinsky method, shell correction calculations need to determine nuclear single particle levels which in our approach are the eigenvectors of a deformed Saxon Woods potential of standard parametrization [@BDJ72]. In practice these states are obtained by an expansion in the basis of a deformed harmonic oscillator. This oscillator basis is an [*one-center*]{} basis which is probably not so well adapted if one is interested in describing shapes near the scission point. Indeed, for such strongly elongated and possibly [*necked-in*]{} surfaces, a [*two-center*]{} basis seems to be more adapted taking the structure of the nascent fragments better into account. We stress this technical detail in order to focus on the importance of a careful determination of shell effects at very large deformations. To illustrate this point we compare on Fig. 11 the fragment mass distribution obtained when the dynamical calculation is artificially stopped at an elongation $c_{scis} = 1.8$ to the one obtained when this calculation is carried through up to the geometrical scission point $c_{scis} \!=\! c_{geo}$ where the splitting into two fragments 