Complex fragments produced with 104 MeV α - particles

The production of complex fragments in light and medium systems such as α + 46 Ti, 58 Ni, nat Ag at 26 MeV nucleon incident energy is reported. Their elemental distributions look rather similar for the three systems, but the cross section absolute values decrease when the mass of the target increases. The nuclear structure and the Pauli principle lose their influence at this projectile velocity: vα 0.23 c - close to the Fermi velocity in nuclei - for which the Fermi spheres in the momentum space of the target and projectile are only slightly overlapping, and the bulk properties of the nuclei are dominant. The measured Z - distributions (up to Z = 16) are reproduced using the extended some rule model calculations, including fusion, incomplete fusion, and dissipative fragmentation of the systems. The Galilei invariant cross-section plots have shown that the isotropic complex fragment emission from a source moving with the center of mass velocity is prevailing. The inclusive data have revealed binary, equilibrium and non-equilibrium reactions modes. A short coincidence run has evidenced more-than-two-body reaction channels too. (Author)