Constraints on the Skyrme Equations of State from Properties of Doubly Magic Nuclei

I use properties of doubly-magic nuclei to constrain nuclear matter and neutron matter equations of state. I conclude that the data determined the value of the neutron equation of state and the symmetry energy near a density of $\rho_{on}$ = 0.10 nucleons/fm$^{3}$. The slope at that point is constrained by the value of the neutron skin.Comment: 5 page, 5 figure

Effects of isospin mixing in the A=32 quintet

For the A=32 T=2 quintet we provide a unified theoretical description for three related aspects of isospin mixing: the necessity of more than three terms in the isobaric mass multiplet equation, isospin-forbidden proton decay, and a correction to the allowed Fermi beta decay. We demonstrate for the first time that all three effects observed in experiment can be traced to a common origin related to isospin mixing of the T=2 states with T=1 states

Modification of the Brink-Axel Hypothesis for High Temperature Nuclear Weak Interactions

We present shell model calculations of electron capture strength distributions in A=28 nuclei and computations of the corresponding capture rates in supernova core conditions. We find that in these nuclei the Brink-Axel hypothesis for the distribution of Gamow-Teller strength fails at low and moderate initial excitation energy, but may be a valid tool at high excitation. The redistribution of GT strength at high initial excitation may affect capture rates during collapse. If these trends which we have found in lighter nuclei also apply for the heavier nuclei which provide the principal channels for neutronization during stellar collapse, then there could be two implications for supernova core electron capture physics. First, a modified Brink-Axel hypothesis could be a valid approximation for use in collapse codes. Second, the electron capture strength may be moved down significantly in transition energy, which would likely have the effect of increasing the overall electron capture rate during stellar collapse.Comment: 15 pages, 19 figure

Neutrino Pair Emission from Hot Nuclei During Stellar Collapse

We present shell-model calculations showing that residual interaction-induced configuration mixing enhances the rate of neutral current de-excitation of thermally excited nuclei into neutrino-antineutrino pairs. Though our calculations reinforce the conclusions of previous studies that this process is the dominant source of neutrino pairs near the onset of neutrino trapping during stellar collapse, our shell-model result has the effect of increasing the energy of these pairs, possibly altering their role in entropy transport in supernovae.Comment: 9 pages, 8 figure

Renormalized interactions with a realistic single particle basis

Neutron-rich isotopes in the sdpf space with Z < 15 require modifications to derived effective interactions to agree with experimental data away from stability. A quantitative justification is given for these modifications due to the weakly bound nature of model space orbits via a procedure using realistic radial wavefunctions and realistic NN interactions. The long tail of the radial wavefunction for loosely bound single particle orbits causes a reduction in the size of matrix elements involving those orbits, most notably for pairing matrix elements, resulting in a more condensed level spacing in shell model calculations. Example calculations are shown for 36Si and 38Si.Comment: 6 page