Bulletin of the American Physical Society
5th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Volume 63, Number 12
Tuesday–Saturday, October 23–27, 2018; Waikoloa, Hawaii
Session MG: Nuclear Theory 4 
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Chair: Yutaka Utsuno, Japan Atomic Energy Agency Room: Hilton King's 3 
Saturday, October 27, 2018 2:00PM  2:15PM 
MG.00001: Microscopic Calculations of Nuclear Level Densities with the Extrapolated Lanczos Matrix (ELM) Method B. Alex Brown, William Ormand, Sofia Karampagia A new method for computing the density of states in nuclei using an extrapolated form for the tridiagonal matrix obtained from the Lanczos method is presented. This can be applied to configurationinteraction calculations with fully realistic nuclear Hamiltonians that are known to provide an excellent description of the lowlying structure of nuclei. This extrapolated Lanczos matrix (ELM) approach provides an accurate computation of the density of states up to the neutron separation energy for states that lie within the configuration space. Comparisons between theory and experiment for the average level spacings for pwave resonances for iron isotopes using the 1p0fshell model space and realistic nuclear Hamiltonians are shown. Also we show results for Jdependence of the level density in ^{57}Fe, the total level density for negativeparity states in ^{57}Fe, and the level density for 2^{+} states in ^{58}Ni in comparison with experiment and with the stochastic method. 
Saturday, October 27, 2018 2:15PM  2:30PM 
MG.00002: Vorticity and deformation in Carbon12 within a symplectic shellmodel framework David Kekejian, Jerry P Draayer, Kristina D Launey The study of rotational bands in nuclei shows that they can deviate from that of a perfect rotor, especially for states with higher angular momentum. To address this, we explore how vorticity in Carbon12 tracks with the deformation flow. This is achieved in the nocore symplectic shell model that utilizes a Hamiltonian with an exponentiated Q.Q interaction. This model offers a microscopic description of a nucleus in terms of mixed deformed configurations and associated rotations and vibrations, while successfully reproducing energy spectra and E2 transitions from light up through intermediatemass nuclei with a single adjustable parameter. This study reveals the important role of vorticity towards the understanding of the underpinning dynamics of rotations in deformed nuclei. 
Saturday, October 27, 2018 2:30PM  2:45PM 
MG.00003: Configuration Interaction studies of Nuclear Clustering Konstantinos Kravvaris, Alexander Volya
The formation of distinct substructures within an atomic nucleus, appropriately termed nuclear clustering, is one of the core questions of nuclear manybody physics. In this work, we study the αcluster aspects of light nuclei by constructing translationally invariant, fully antisymmetrized cluster reaction channels and combining them with Configuration Interaction approaches and the Resonating Group Method. We discuss signatures of αclustering within the modern shell model and the emergence of cluster rotational bands from a No Core Shell Model perspective. 
Saturday, October 27, 2018 2:45PM  3:00PM 
MG.00004: Selfconsistent multiparticlemultihole configuration mixing description of nuclear manybody systems Caroline Robin, Nathalie Pillet Manybody methods such as shell models or selfconsistent mean fields remain among the most used and powerful approaches to the description of nuclei. Based on different philosophies, these methods however differ in the range of masses and physical phenomena they can describe. In this talk we present an approach to nuclear structure that is at the crossroads between these two concepts. This method is based on the determination of a general wave function taken as a superposition of Slater determinants built on a singleparticle basis that is solution of a generalized meanfield equation. Full selfconsistency is reached as the individual orbitals incorporate part of the nuclear correlations and, in turn, minimize residual manybody interactions. We will present applications of the method to ground and spectroscopic properties of p and sdshell nuclei [1]. The impact of the optimization of the orbitals will be emphasized. [1] C. Robin et al., Phys. Rev. C 93, 024302 (2016); C. Robin et al, Phys. Rev. C 95, 044315 (2017). 
Saturday, October 27, 2018 3:00PM  3:15PM 
MG.00005: Shortrange correlations and the proton 3s_{1/2} wave function in ^{206}Pb Shalom Shlomo, Igal Talmi, Mason Robert Anders, Giacomp Bonasera We consider the experimental data for the charge density difference between the isotones ^{206}Pb – ^{205}Tl, deduced by analysis of elastic electron scattering measurements and corresponds to the shell model 3s_{1/2} proton orbit, and investigate the effects of twobody shortrange correlations. This is done by: (a) Determining the corresponding single particle potential (meanfield), employing a novel method, directly from the single particle matter density and its first and second derivatives and also by leastsquare fits to parametrized single particle potentials; (b) Determining the shortrange effect by employing the Jastrow correlated manybody wave function to derive a density dependent correlation factor for the densities of single particle orbits. The 3s_{1/2 }wave functions of the determined potentials reproduce fairly well the experimental data within the quoted errors. Moreover, the calculated 3S_{1/2 }density obtained with the inclusion of the shortrange correlation effect does not reproduce the experimental data. More accurate experimental data, with uncertainty smaller by a factor of two or more, may answer the question how well can the data be reproduced by a calculated 3s_{1/}2 single particle wave function.

Saturday, October 27, 2018 3:15PM  3:30PM 
MG.00006: ABSTRACT WITHDRAWN

Saturday, October 27, 2018 3:30PM  3:45PM 
MG.00007: Microscopic optical potential for proton elastic scattering off light exotic nuclei Matteo Vorabbi A microscopic optical potential (OP) for intermediate energies is derived using ab initio translationally invariant nonlocal onebody nuclear densities computed within the nocore shell model approach. Two and threenucleon chiral interactions are the only input of our calculations and are used to compute consistently the nuclear density and the nucleonnucleon t matrix, which represent the two basic ingredients for the OP computation. The ground state local and nonlocal densities of several nuclei are calculated and applied to OP construction. The differential cross sections and the analyzing powers for the elastic proton scattering off these nuclei are then calculated for different values of the incident proton energy. The model is first tested on ^{4}He, ^{12}C, and ^{16}O, and then is used to compute and compare the results for ^{6,8}He elastic scattering off polarized protons with the existing experimental data at 71 MeV/u. For ^{6}He we also provide some predictions at 200 MeV/u that can be useful to interpret the data of a new experiment recently performed at RIKEN. 
Saturday, October 27, 2018 3:45PM  4:00PM 
MG.00008: YAHFCMC: A Monte Carlo based HauserFeshbach Reaction Code System William Ormand A computer code system, YAHFCMC, for treating nuclear reactions within the statistical decay framework, i.e., HauserFeshbach, and its extensions will be presented. The code system is based on a Monte Carlo, eventbyevent simulation of the nuclear reaction, which allows for the study of spectral correlations between emitted particles. The code system is flexible and controlled by a series of input commands allowing access to all reaction parameters. The code system supports both traditional reaction calculations, as well as decays from initial populations, which is useful for the analysis of surrogate reaction experiments. YAHFCMC is written in FORTRAN 95 making use of dynamic memory allocation and derived types. The code is interfaced with the optical model computer codes FRESCO and ECIS, which allows easy access to a wide range of direct processes. Reaction calculations generate nuclear data libraries that are suitable for insertion into the Generalized Nuclear Data (GND) structure. Examples of calculations contained in a recent evaluation for ^{240242}Am will be presented. 
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