Session C4: Nuclear Physics

Friday, October 15, 2010

The $^{12}$C($^{6}$He, $^{4}$He) transfer reaction was performed using SHARC, a charged particle detector array, and TIGRESS, a $\gamma $ detector array, at the TRIUMF/ISAC-II facility. The aim of this study is to investigate how the two halo neutrons of $^{6}$He can be transferred, as compared to the two neutrons of a much more compact nucleus, such as tritium. Initial results will be presented as well as future work.   

Friday, October 15, 2010

A new nuclear model is proposed based on the three-quark structure of nucleons, which form triangular ``ovoids.'' Nucleons combine via a set of rules: the strong/color force between quarks holds protons and neutrons together subject to the exclusion principle. Electric and magnetic forces between quarks attract or repel to determine lattice alignment of nucleons. Magnetic dipoles lock protons and neutrons into specific structural positions which determine the overall spin of an isotope. Mechanical balance and volume minimization are other important factors. The model describes the buildup of all stable and unstable nuclei in stages. The deuteron has the shape of a triangular prism, the alpha a hexagonal prism. In this lattice model protons are only nearest neighbors to neutrons and next-nearest neighbors to protons. Zome constructs are used to build ``tinker-toy-like'' physical models to aid visualization. Carbon-12 forms a ring structure of three interconnected alpha particles. The model is further discussed at unclear2nuclear.com.   

Friday, October 15, 2010

The new quark-lattice model of the nucleus has been extended through heavy nuclei. Three specific issues illustrate the power of the model: (1) large thermal neutron absorption cross sections, (2) radioactive decay of K-40, and (3) asymmetric fission. Large neutron absorption cross sections occur when there are openings in the lattice into which neutrons can naturally fit. Examples are He-3, Li-6, and B-10. B-10 results in neutron-activated fission. The decay of K-40 into either Ar-40 or Ca-40 illustrates the role spin plays in determining nuclear structure. K-40 has net spin 4 whereas Ar-40 and Ca-40 both have spin 0. Zome models are used to show these structures. The fission of heavy nuclei occurs, in the lattice model, as the core of the structure separates from the loosely-packed ends. The ends are repacked into a smaller nucleus, which forms the lighter of the two daughter fragments. This explains why the lighter fragment mass increases with total mass whereas the heavier fragment mass remains relatively constant.