The entrance channel effects on the deexcitation ways of the same compound nucleus at a fixed excitation energy

The investigation of various properties of deexcitation of the same ²²⁰Th compound nucleus (CN), formed by the different mass (charge) asymmetric ¹⁶O+²⁰⁴Pb, ⁴⁰Ar+¹⁸⁰Hf, ⁸²Se+¹³⁸Ba and ⁹⁶Zr+¹²⁴Sn reactions is presented. The effective fission barrier < B _fis > value, as a function of the excitation energy $E_{CN}^{\ast }$, determined for each intermediate excited nucleus reached along the deexcitation cascade of the CN obtained by the four considered reactions is strongly sensitive to the various orbital angular momentum L=ℓℏ distributions of CN formed with the same excitation energy $E_{CN}^{\ast }$ by the various entrance channels. Therefore, the competition between the fission and evaporation of light particles (neutron, proton, and α-particle) processes along the deexcitation cascade of CN is dependent on the orbital angular momentum distribution of CN. In fact, the ratio between the evaporation residue cross sections obtained when also the charged particles are emitted and the ones obtained after neutron emission only for the same CN with a fixed excitation energy $E_{CN}^{\ast }$ is sensitive to the mass (charge) asymmetry of the entrance channel. (paper)