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The role played by quasi-elastic and inelastic break-up of the 12C and 16O projectiles in the production of intermediate mass fragments at 14-35 MeV/uMira, Joele Paulus 12 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: See full text for the abstract / AFRIKAANSE OPSOMMING: Sien volteks vir die opsomming
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Fragmentation in Proton-Nucleus Reactions from 100 to 1400 MeVJäderström, Henrik January 2008 (has links)
The heaviest fragments, recoils, have been studied in proton and deuteron induced 28Si reactions and proton-20Ne reactions at 100-300 MeV per nucleon. Inclusive charge and angular distributions and coincidences between He nuclei and recoils have been compared to two theoretical models, Dubna Cascade Model and JAERI Quantum Molecular Dynamics. The overall agreement was good for the reactions with 28Si, however the angular distributions of He fragments could not be reproduced. For the 20Ne reactions the recoil angular distributions were only reproduced for large angles. There was a significant underestimation at small angles and low recoil charge. α-clustering in the bombarding nucleus is a possible explanation for the deviations. In the 100 MeV per nucleon reactions all assumptions of the models may not be valid and the agreement was worst for these reactions. In proton-natXe reactions intermediate mass fragments have been studied from 200 to 1400 MeV. Slow ramping was used to scan the energy. Charge distributions and a caloric curve have been compared to Cascade Fragmentation Evaporation Model. Charge distributions showed good agreement for fragments with Z<8 but the heavier fragments were underestimated.
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Transverse Collective Flow and Emission Order of Mid-Rapidity Fragments in Fermi Energy Heavy Ion CollisionsKohley, Zachary Wayne 2010 August 1900 (has links)
The Equation of State (EoS) of asymmetric nuclear matter has been explored through the study of mid-rapidity fragment dynamics from the 35 MeV/u $^{70}$Zn $^{70}$Zn, $^{64}$Zn $^{64}$Zn, and $^{64}$Ni $^{64}$Ni systems. The experimental data was collected at the Texas A and M Cyclotron Institute using the 4 NIMROD-ISiS array, which provided both
event characterization and excellent isotopic resolution of charged particles.
The transverse collective flow was extracted for proton, deuteron, triton, 3He,
alpha, and 6He particles. Isotopic and isobaric effects were observed in the transverse
flow of the fragments. In both cases, the transverse flow was shown to decrease
with an increasing neutron content in the fragments. The (N/Z)sys dependence of
the transverse flow and the difference betwen the triton and 3He flow were shown to
be sensitive to the density dependence of the symmetry energy using the stochastic
mean-field model. A stiff parameterization of Esym(p) was found to provide better
agreement with the experimental data.
The transverse flow for intermediate mass fragments (IMFs) was investigated,
providing a new probe to study the nuclear EoS. A transition from the IMF flow
strongly depending on the mass of the system, in the most violent collisions, to a
dependence on the charge of the system, for the peripheral reactions, was observed.
Theoretical simulations were used to show that the relative differences in the IMF flow
are sensitive to the density dependence of the symmetry energy. The best agreement
between the experiment and theory was achieved with a stiff Esym(p).
A new method was developed in which correlations between the projectile-like
and mid-rapidity fragments were examined using a scaled flow. Theoretical simulations
were used to show that the scaled flow of the particles was connected to their
average order of emission. The experimental results suggest that the mid-rapidity
region is preferentially populated with neutron-rich light charged particles and the
Z=3-4 IMFs at a relatively early stage in the collision.
This work presents additional constraints on the nuclear EoS and insight into
the mid-rapidity dynamics observed in Fermi energy heavy-ion collisions.
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