New developments in the nuclear binary cluster-core in the heavy nuclear region

Kaya, Boniface Dimitri Christel Kimene (2018-03)

Thesis (PhD)--Stellenbosch University, 2018.

Thesis

ENGLISH ABSTRACT : The atomic nucleus is a complex many-body interacting system, which exhibits a underlying correlated set of nucleon states. The cluster model is one of the most reliable models that predicts the strongly correlated subsystem of nucleons close to the decay threshold of nuclei. The binary-cluster model describes the structure and decay properties of super-heavy nuclei. The phenomenological CubicWoods-Saxon potential, developed by Buck, Merchant and Perez, has successfully predicted a number of experimental observables associated with clustering phenomenon. The recently developed microscopic double folded M3Y potential results in the inverted spectra for the positive parity excited cluster states, but successfully predicts the decay halflife for the α-Pb system. These shortcoming of the M3Y based microscopic binary cluster model lead to the newly developed hybrid cluster-core potential, obtained by fitting the phenomenological Saxon-Woods Cubed and the M3Y double folding at the surface region where the two potentials coalesce. The project presents an overview on nuclear cluster models. The double folding potentials are constructed with the M3Y and the new complex effective Gaussian form factor (CEG) effective nucleon-nucleon interactions. Furthermore the recently developed self-consistent relativistic mean-field cluster-core description is presented with the relativistic Love-Franey amplitudes. The decay half-lives for α-Pb give satisfactory results for M3Y and CEG with the addition of a zero-range exchange potential. However, the CEG with a finite-range and the relativistic mean field approach potentials for all cluster-core configurations α-Pb, C-Pb and O-Pb except Be-Pb, give decay half-lives that overestimate the experimental values. The generated positive parity level structures are inverted for α -Pb when compared to other cluster configurations which are compressed although positive. Finally we construct the hybrid cluster-core potential from different microscopic potential models. We find that predictions for the positive parity level structure, the transition probability, nuclear charge radii and deformation parameters are in good agreement with the corresponding experimental data for most cluster-core configurations.

AFRIKAANSE OPSOMMING : Die atoomkern is ’n komplekse veeldeeltjie interaksie sisteem, wat die onderliggende korrelasies van nukleon toestande uitlig. Die bondel model is een van die mees betroubare modelle wat die sterk korrelerende subsisteem van nukleone naby die drumpel van kern verval voorspel. Die binêre-bondel model beskryf die struktuur en verval eienskappe van super swaar kerne. Die fenomenologiese Kubiese Woods-Saxon potensiaal, beskryf deur Buck, Merchant en Perez, is suksesvol in die beskrywing van ’n aantal eksperimentele waarneembares wat geassosieer word met die bondelings verskynsel. Die onlangse ontwikkelde mikroskopiese dubbele gevoude M3Y potensiaal gee ’n omgekeerde spektrum van die positiewe partiteit opgewekte toestande, maar is sukselvol in die voorspelling van die verval halfleeftyd van die α-Pb sisteem. Hierdie tekortkomminge van die M3Y gebaseerde mikroskopiese binêre-bondel model lei tot die nuut ontwikkelde hibried bondel-kern potensiaal, deur die fenomenologiese Kubiese Woods-Saxon potensiaal en die M3Y dubbel gevoude potensiaal by die oppervlak gebied waar die twee potensiale oorvleuel, te pas. Die projek bied aan ’n oorsig van kern bondel modelle. Die dubbelgevoude potensiale is gekonstrueer deurmiddel van die M3Y en die nuwe kompleks effektiewe Gaussian vorm faktor (CEG). Verder word die onlangse self konsistente ontwikkelde relatiwistiese gemideelde veld bondel-kor beskryf. Dieverval halfleeftyd van α-Pb gee bevredigende resultate vir M3Y en CEG met die byvoeging van ’n nul reeks ruil potensiaal. Alhoewel CEG met ’n eindigende reeks en relatiwistiese gemiddelde veld benadering, word potensiale vir alle konfigurasies van α-Pb, C-Pb and O-Pb geproduseer, behalwe vir Be-Pb, wat die eksperimentele waardes oorskat het. Die genereerde positiewe pariteitsvlak strukture is omgekeerd vir α-Pb wannneer dit vergelyk word met die ander bondel opset wat saamgepers is. Laastens was die hibride bondel-kor potensiaal van verskillende mikroskopiese potensiale gekonstrueer. Die voorspellings van die positiewe pariteitsvlak strukture was gekry. Die oorgangs waarskynlikheid, kernladings radius en vervormings parameters stem ooreen met die ooreenstemmende eksperimentele data vir meeste van die bondel-kern konfigurasies.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/103546
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