  Formally, the cross section for producing a heavy evaporation residue,
{\sigma}EVR, in a fusion reaction can be written as. \begin{equation}
\sigma_{\rm EVR}(E)=\frac{\pi h^2}{2\mu E}\sum\limits_{\ell=0}^\infty
(2\ell+1)T(E,\ell)P_{\rm CN}(E,\ell)W_{\rm sur}(E,\ell), \end{equation} where E
is the center of mass energy, and T is the probability of the colliding nuclei
to overcome the potential barrier in the entrance channel and reach the contact
point. PCN is the probability that the projectile-target system will evolve
from the contact point to the compound nucleus. Wsur is the probability that
the compound nucleus will decay to produce an evaporation residue rather than
fissioning. However, one must remember that the Wsur term effectively sets the
allowed values of the spin, which in turn, restricts the values of the capture
and fusion cross sections. We point out the implications of this fact for
capture cross sections for heavy element formation reactions.
