Fragment emission in Ca+Ca reactions
at 25
MeV/nucleon, I.
Lombardo, Univ. Federico
II, Napoli and INFN-Sez.
Napoli, Italy − We present experimental data concerning 40,48Ca+40,48Ca
reactions
at 25 MeV/nucleon. The
4π
multi-detector Chimera has been used as detection device. Various effects due to the
different neutron
to proton ratios (N/Z) of entrance channels have been
investigated.First
of all, strong isotopic effects are
seen in inclusive emission of light fragments. Moreover, Z and N
distributions of light
fragments are characterized by even-odd oscillations, whose
amplitude seems to
be related to the neutron richness of entrance channel.In semi-peripheral
collisions, isospin
diffusion signals have been found. They
were
investigated by analyzing isobaric emission (7Li/7Be)
from
quasi-projectile sources formed in the four studied systems. They
claim
for an incomplete charge equilibrium reached by the di-nuclear
system during
the interaction phase.The
emission of
evaporation residues in semi-central collisions was also
investigated. We
found that the N/Z degree of freedom plays
an important role on the fate of hot quasi-fusion sources formed;
in
particular, the larger is the neutron content of entrance channels
and the
larger is the emission of evaporation residues. Experimental data have
been compared with
CoMD-II model calculations, and we find that a moderately stiff
symmetry
potential have to be used to reproduce satisfactorily the data.