  Characteristic quantities such as the penetration and preformation
probabilities, assault frequency and tunneling times in the tunneling
description of alpha decay of heavy nuclei are explored to reveal their
sensitivity to neutron numbers in the vicinity of the magic neutron number $N$
= 126. Using realistic nuclear potentials, the sensitivity of these quantities
to the parameters of the theoretical approach is also tested. An investigation
of the region from $N=116$ to $N=132$ in Po nuclei reveals that the tunneling
$\alpha$ particle spends the least amount of time with an $N=126$ magic
daughter nucleus. The shell closure at $N=126$ seems to affect the behaviour of
the dwell times of the tunneling alpha particles and this occurs through the
influence of the $Q$-values involved.
