N/z equilibration in deep inelastic collisions and the fragmentation of the resulting quasiprojectiles

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Title: N/z equilibration in deep inelastic collisions and the fragmentation of the resulting quasiprojectiles
Author: Keksis, August Lawrence
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 .
URI: http : / /hdl .handle .net /1969 .1 /5886
Date: 2007-09-17

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N/z equilibration in deep inelastic collisions and the fragmentation of the resulting quasiprojectiles. Available electronically from http : / /hdl .handle .net /1969 .1 /5886 .

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