  Dissipative dynamics of nuclear fission is a well confirmed phenomenon
described either by a Kramers-modified statistical model or by a dynamical
model employing the Langevin equation. Though dynamical models as well as
statistical models incorporating fission delay are found to explain the
measured fission observables in many studies, it nonetheless shows conflicting
results for shell closed nuclei in the mass region 200. Analysis of recent data
for neutron shell closed nuclei in excitation energy range 40$-$80 MeV failed
to arrive at a satisfactory description of the data and attributed the mismatch
to shell effects and/or entrance channel effects, without reaching a definite
conclusion. In the present work we show that a well established stochastic
dynamical code simultaneously reproduces the available data of pre-scission
neutron multiplicities, fission and evaporation residue excitation functions
for neutron shell closed nuclei $^{210}$Po and $^{212}$Rn and their isotopes
$^{206}$Po and $^{214,216}$Rn without the need for including any extra shell or
entrance channel effects. The calculations are performed by using a
phenomenological universal friction form factor with no ad-hoc adjustment of
model parameters. However, we note significant deviation, beyond experimental
errors, in some cases of Fr isotopes.

Nuclear Theory;Nuclear Experiment