Bulletin of the American Physical Society
APS April Meeting 2016
Volume 61, Number 6
Saturday–Tuesday, April 16–19, 2016; Salt Lake City, Utah
Session M9: Nuclear Theory 
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Sponsoring Units: DNP Chair: Jorge Lopez, UTEP Room: 250A 
Sunday, April 17, 2016 3:30PM  3:42PM 
M9.00001: Adependence of the Spectra of the F Isotopes from ab initio Calculations Bruce R. Barrett, Erdal Dikmen, Pieter Maris, James P. Vary, Andrey M. Shirokov Using a succession of OkuboLeeSuzuki transformations within the No Core Shell Model (NCSM) formalism [1], we derive an ab initio, nonperturbative procedure for calculating the input for standard shellmodel (SSM) calculations within one major shell. We have used this approach for calculating the spectra of the F isotopes from A=18 to A=25, so as to study the Adependence of the results. In particular, we are interested in seeing if the theoretical input is weak enough, so that a single set of twobody effective interactions can be used for all of the F isotopes investigated. We will present results from SSM calculations based on input obtained with the JISP16 nucleonnucleon interaction in an initial $4\hbar\Omega$ NCSM basis space. 1. E. Dikmen et al., Phys. Rev. C 91, 064301 (2015). [Preview Abstract] 
Sunday, April 17, 2016 3:42PM  3:54PM 
M9.00002: Coupledcluster theory computation of the nuclear electric dipole polarizability Sonia Bacca, Mirko Miorelli, Nir Barnea, Gaute Hagen, Giuseppina Orlandini, Thomas Papenbrock The electric dipole polarizability $\alpha_D$ is strongly correlated with the size of atomic nuclei. It informs us about the neutron equation of state and links atomic nuclei to neutron stars. In recent years, scattering experiments have been used to determine the dipole polarizability in $^{208}$Pb [1], $^{120}$Sn [2] and $^{68}$Ni [3]. Combining the Lorentz integral transform with the coupledcluster method allows us to perform ab initio computations of $\alpha_D$ for medium mass nuclei [4,5]. In Ref. [6] we predicted the polarizability for $^{48}$Ca and presently we are investigating heavier systems such as $^{68}$Ni and $^{90}$Zn. [1] A. Tamii et al., Phys. Rev. Lett. 107, 062502 (2011). [2] T. Hashimoto et al., Phys. Rev. C 92 031305 (2015). [3] D.M. Rossi, et al., Phys. Rev. Lett. 111, 242503 (2013). [4] S. Bacca, N. Barnea, G. Hagen, M. Miorelli, G. Orlandini and T. Papenbrock, Phys. Rev. C 90, 064619 (2014). [5] M. Miorelli, S. Bacca, N. Barnea, G. Hagen, G. Orlandini and T. Papenbrock, in preparation. [6] G. Hagen, et al., Nature Physics, 3529 (2015). [Preview Abstract] 
Sunday, April 17, 2016 3:54PM  4:06PM 
M9.00003: Shell Model Nuclear Level Densities using the Methods of Statistical Spectroscopy Sofia Karampagia, Roman Sen'kov, Vladimir Zelevinsky, Alex B. Brown An algorithm has been developed$^{1}$ for the calculation of spin and paritydependent nuclear level densities, based on a twobody shellmodel Hamiltonian. Instead of diagonalizing the full shellmodel Hamiltonian, the algorithm uses methods of statistical spectroscopy in order to derive nuclear level densities. This method allows one to calculate the exact level densities (coinciding with the shell model densities) very fast and for model spaces that the shell model cannot reach. In this work we study the evolution of the level density under variation of specific matrix elements of the shellmodel Hamiltonian. We also study the impact on the calculated level density as a result the expansion of singleparticle model space. As an application of the method, whenever it is possible and experimental information exists, we make a comparison of the nuclear level densities calculated within our method with experimental level densities. \\R. A. Sen'kov, M. Horoi, V. G. Zelevinsky, A highperformance Fortran code to calculate spin and paritydependent nuclear level densities, \it{Com. Phys. Comm.} \bf {184 (2013) 215.} [Preview Abstract] 
Sunday, April 17, 2016 4:06PM  4:18PM 
M9.00004: Large Scale Quantum Simulations of Nuclear Pasta Farrukh J. Fattoyev, Charles J. Horowitz, Bastian Schuetrumpf Complex and exotic nuclear geometries collectively referred to as "nuclear pasta" are expected to naturally exist in the crust of neutron stars and in supernovae matter. Using a set of selfconsistent microscopic nuclear energy density functionals we present the first results of large scale quantum simulations of pasta phases at baryon densities $0.03 < \rho < 0.10$ fm$^{3}$, proton fractions $0.05 < Y_{\rm p} < 0.40$, and zero temperature. The full quantum simulations, in particular, allow us to also study the role and impact of the nuclear symmetry energy on these pasta configurations. [Preview Abstract] 
Sunday, April 17, 2016 4:18PM  4:30PM 
M9.00005: Phase Diagrams of Nuclear Pasta Matthew Caplan, Chuck Horowitz, Don Berry, Andre da Silva Schneider In the inner crust of neutrons stars, where matter is near the saturation density, protons and neutrons arrange themselves into complex structures called nuclear pasta. Early theoretical work predicted a simple graduated hierarchy of pasta phases, consisting of spheres, cylinders, slabs, and uniform matter with voids. Previous work has simulated these phases with a simple classical model and has shown that the formation of these structures is dependent on the temperature, density, and proton fraction. However, previous work only studied a limited range of these parameters due to computational limitations. Thanks to recent advances in computing it is now possible to survey the structure of nuclear pasta for a larger range of parameters. By simulating nuclear pasta with constant temperature and proton fraction in an expanding simulation volume we are able to study the phase transitions in nuclear pasta, and thus produce a set of phase diagrams. We report on these phase diagrams as well as newly identified phases of nuclear pasta and discuss their implications for neutron star observables. [Preview Abstract] 
(Author Not Attending)

M9.00006: The equation of state of dense QCD and the stability of massive neutron stars Philip Powell, Gordon Baym, Toru Kojo, Yifan Song The properties of extreme quantum chromodynamic (QCD) matter have historically been largely a matter of speculation, with predictions heavily dependent on model assumptions or asymptotic approximations. However, recent neutron star mass and radius measurements, heavyion collision experiments, and lattice QCD simulations are providing the first significant empirical insights into the QCD phase diagram and present an opportunity to constrain effective models of extreme QCD matter. We investigate a hybrid nuclearquark model that incorporates the wellestablished properties of hadronic matter at densities $<2$ times nuclear density ($n_0$) with a symmetrybased interacting quark model expected to be valid for densities above $\sim(46)n_0$. By obtaining empirical constraints on model parameters, we demonstrate the possibility of a smooth crossover between low temperature hadronic and quark matter at $\sim(23)n_0$, characterized by a gradual onset of the quark degrees of freedom with increasing density. Such a crossover is consistent with the stability of neutron stars of mass $\gtrsim 2$ solar masses. Finally, we obtain significant constraints on the structure of the QCD phase diagram, including the location of possible critical points and dense superfluid quark matter. [Preview Abstract] 
Sunday, April 17, 2016 4:42PM  4:54PM 
M9.00007: Constrained HartreeFock Theory and Study of Deformed Structures of Closed Shell Nuclei Choudhury Praharaj We have studied some N or Z = 50 nuclei in a microscopic model with effective interaction in a reasonably large shell model space. Excitation of particles across 50 shell closure leads to welldeformed excited prolate configurations. The potential energy surfaces of nuclei are studied using HartreeFock theory with quadrupole constraint to explore the various deformed configurations of N = 50 nuclei $^{82}Ge$, $^{84}Se$ and $^{86}Kr$. Energy spectra are calculated from various intrinsic states using PeierlsYoccoz angular momentum projection technique. Results of spectra and electromagnetic moments and transitions will be presented for N = 50 nuclei and for Z = 50 $^{114}Sn$ nucleus. [Preview Abstract] 
Sunday, April 17, 2016 4:54PM  5:06PM 
M9.00008: Nuclear Checker Board Model Theodore Lach The NCB Model $^{1,2,3}$ suggests that the nucleus is a relativistic 2D structure. In 1996 at Argonne National Lab the Checker Board Model was first presented. In that poster presentation it was explained that the relativistic constituent quarks orbit inside the proton at about 85{\%} c and about 99{\%} c inside the neutron. As a way to test the model it was found that the de Broglie wavelength of the up quark matched the calculated circumference of the proton (radius $=$ 0.5194 fm) analogous to the Bohr model of the electron in the H atom. 20 years later it is now accepted that the quarks are moving at relativistic speeds and the orbital motion of the quarks contribute the major part of the spin of the proton. If one considers the motion of the relativistic quarks inside the nucleus (take for example Ca 40) about its center of mass, one realizes that these relativistic quarks are confined to \textbf{\textit{shells}} inside the nucleus (the He shell \textbraceleft the inner 4 nucleons\textbraceright , the Oxygen shell \textellipsis ). So the CBM eliminates the need for an illusionary strong nuclear force in favor of a force based upon an E/M force in perfect spin synchronization in a 2D plane. So the CBM is not at odds with the shell model but instead explains why the nucleus has a shell structure and correctly predicts the shell closures. \begin{enumerate} \item ``Nuclear Structure at the limits'' July 23$^{rd}$, 1996. \item Checkerboard Structure of the Nucleus, Infinite Energy, \textbf{5}, issue 30, March 2000. \item Website:http://checkerboard.dnsalias.net \end{enumerate} [Preview Abstract] 
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