  The properties of deexcitation of the same $^{220}$Th compound nucleus (CN)
formed by different mass (charge) asymmetric reactions are investigated. It is
demonstrated that the effective fission barrier $<B_{\rm fis}>$ value being a
function of the excitation energy $E^*_{\rm CN}$ is strongly sensitive to the
various orbital angular momentum $L=\ell\hbar$ distributions of CN formed with
the same excitation energy $E^*_{CN}$ by the very different entrance channels
$^{16}$O+$^{204}$Pb, $^{40}$Ar+$^{180}$Hf, $^{82}$Se+$^{138}$Ba and
$^{96}$Zr+$^{124}$Sn. Consequently, the competition between the fission and
evaporation of light particles (neutron, proton, and $\alpha$-particle)
processes along the deexcitation cascade of CN depends on the orbital angular
momentum distribution of CN. Therefore, the ratio between the evaporation
residue cross sections obtained after emission of neutral and charged particles
and neutrons only for the same CN with a given excitation energy $E^*_{CN}$ is
sensitive to the mass (charge) asymmetry of reactants in the entrance channel.
