In this work we study the decay modes of excited nuclei formed in 78,82Kr+40Ca reactions at 5.5 AMeV. The 4p INDRA array was used to measure light charged particles, evaporation residues and fragments with atomic number 3 ≤ Z ≥ 28. In both reactions, fragment characteristics are compatible with a fissionlike phenomenon. Persistence of structure effects is evidenced from a strong odd-even staggering of the light-fragment (6 ≤ Z ≥ 11) yields. The magnitude of the staggering does not significantly depend on the neutron content of the system. Light particle-fragment coincidences suggest that those fragments are excited below the particle emission thresholds. For the neutron-poor system, the evaporation residue cross-section is slightly higher and the fission-like component is larger by ~ 25%. These features were confronted to the predictions of statistical and dynamical models. For both reactions, the transition-state formalism reasonably reproduces the Z-distribution around the symmetry but strongly overestimates the light-fragment cross-sections and failed to explain the staggering of their yields. The Z-distribution shape and the staggering of the light-fragment yields are satisfactorily reproduced within the dinuclear system framework which associates the heavy fragments to quasifission while light fragments are predominantly populated by fusion. However, none of the models are able to reproduce the characteristics of the kinetic energy spectra. This would indicate the need to improve the description of large deformation experienced by the system at the separation phase.
Decay of excited nuclei produced in $^{78,82}$Kr+$^{40}$Ca reactions at 5.5 AMeV