Abstract:

When target and projectile nuclei have a difference in neutron to proton ratio (N /Z ) ,
the quasiprojectiles formed in a deep inelastic collision (DIC ) should have a mean
N /Z between the N /Z of the target and the N /Z of the projectile , depending on the
amount of N /Z equilibration that occurred . Data from six reaction systems at two
beam energies (32 and 45 MeV /nucleon ) were collected . The systems in order of
increasing difference between target and projectile N /Z (shown in parentheses ) are
40Ar + 112Sn ( ? ? ? ? ? ?N /Z = 0 .018 ) , 48Ca + 124Sn ( ? ? ? ? ? ?N /Z = 0 .080 ) , 48Ca + 112Sn ( ? ? ? ? ? ?N /Z
= 0 .160 ) , 40Ca + 112Sn ( ? ? ? ? ? ?N /Z = 0 .240 ) , 40Ar + 124Sn ( ? ? ? ? ? ?N /Z = 0 .258 ) and 40Ca +
124Sn ( ? ? ? ? ? ?N /Z = 0 .480 ) .
The quasiprojectile N /Z was determined by two techniques . The first technique
used the isotopically resolved fragments to reconstruct the quasiprojectile N /Z . The
second technique , developed in this thesis , used fragment yield ratios and a simple
equation to simultaneously fit all six systems to determine the quasiprojectile N /Z .
Simulations and a filter of the FAUST (Forward Array Using Silicon Technology ) acceptance
were used to calculate neutron loss ; this accounted for the difference between
the two techniques .
To study the fragmentation of quasiprojectiles the fragment yields were used to
calculate the isobaric , isotopic , fractional and mean N /Z yields . The results showed
that as neutron richness increased , more neutron rich fragments were produced . In addition observation showed evidence for an inhomogeneous distribution of N /Z between
the light charged particles (LCPs Z less than 3 ) and intermediate mass fragments
(IMFs Z greater than 2 ) .
The theoretical results , which used different values of the symmetry energy , were
compared to experimental data to determine which symmetry energy best represents
the experimental data . The comparison showed the experimental data was the overall
best fit with a lower value of the symmetry energy . These results were not conclusive
and further investigation is required . 