TIME-DEPENDENT SCHRODINGER APPROACH TO SUBBARRIER FISSION

The time-dependent Schrodinger equation for the fission of At-213 thro ugh a one-dimensional potential barrier was solved numerically within a finite spatial grid. Several initial quasi-stationary vibrational st ates at and below the top of the barrier were considered. The time dep endence of the decay rate lambda(t) was calculated. The non-exponentia l evolution of the process in the very early stages (less than or equa l to 10(-20) s) differs considerably from the asymptotic (stationary) one. Fission is therefore delayed by the sum of this preexponential ti me, of the tunneling time and of the time necessary for the descent fr om the outer turning point to the scission point. These non-dissipativ e quantum times play the same role as the classical transient times us ually included in the analyses of experimental data on pre-scission em ission of light particles and gamma rays.