Bulletin of the American Physical Society
2007 APS April Meeting
Volume 52, Number 3
Saturday–Tuesday, April 14–17, 2007; Jacksonville, Florida
Session X16: Nuclear Theory II |
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Sponsoring Units: DNP Chair: Alexander Volya, Florida State University Room: Hyatt Regency Jacksonville Riverfront City Terrace 12 |
Tuesday, April 17, 2007 10:45AM - 10:57AM |
X16.00001: Structure of p-shell nuclei with two- plus three-nucleon interactions from chiral effective field theory Petr Navratil, Vesselin Gueorguiev, James Vary, Erich Ormand, Andreas Nogga Properties of finite nuclei are evaluated with two-nucleon (NN) and three-nucleon (NNN) interactions derived within chiral effective field theory (EFT). The nuclear Hamiltonian is fixed by properties of the $A=2$ system, except for two low-energy constants (LECs) that parameterize the short range NNN interaction. We constrain those two LECs by a fit to the $A=3$ system binding energy and investigate sensitivity of $^4$He, $^6$Li, $^{10,11}$B and $^{12,13}$C properties to the variation of the constrained LECs. We identify a preferred choice that gives globally the best description. We demonstrate that the NNN interaction terms significantly improve the binding energies and spectra of mid-$p$-shell nuclei not just with the preferred choice of the LECs but even within a wide range of the constrained LECs. At the same time, we find that a very high quality description of these nuclei requires further improvements to the chiral Hamiltonian. [Preview Abstract] |
Tuesday, April 17, 2007 10:57AM - 11:09AM |
X16.00002: ABSTRACT WITHDRAWN |
Tuesday, April 17, 2007 11:09AM - 11:21AM |
X16.00003: A Cluster Model of $^{ 6}$He and $^{6}$Li Jeremy Armstrong, Alexander Sakharuk, Vladimir Zelevinsky Light nuclei provide an ideal testing ground of few-body theories. 6He is particularly interesting in that it shows an extended particle distribution similar to a halo nucleus, is loosely bound, and is a Borromean system alpha+two neutrons. We apply the Brink Formalism of multi-center shell model in secondary quantization to study the structure of 6He and close nuclei. This variational formalism gives a clear geometric picture of the many-body wave function and allows for the proper treatment of Fermi statistics and correct projection into eigenstates of angular momentum for various competing spatial configurations. The alpha plus dineutron configuration and ``cigar'' [(neutron, alpha, neutron)-chain] configuration were studied to obtain binding energies, charge radii, matter radii, and gamma transition probabilities for 6He. The same configurations were used to obtain the observables for 6Li and calculate the lifetime for Gamow-Teller beta decay of 6He. [Preview Abstract] |
Tuesday, April 17, 2007 11:21AM - 11:33AM |
X16.00004: Coupled-Cluster and Configuration-Interaction Calculations for Heavy Nuclei M. Horoi, J.R. Gour, M. Wloch, M.D. Lodriguito, P. Piecuch, B.A. Brown We compare coupled-cluster (CC) and configuration-interaction (CI) results for $^{56}$Ni obtained in the $pf$-shell basis, focusing on practical CC approximations that can be applied to systems with dozens or hundreds of correlated fermions. The weight of the reference state and the strength of correlation effects are controlled by the gap between the $f_{7/2}$ orbit and the $f_{5/2},p_{3/2},p_{1/2}$ orbits. Independent of the gap, the CC method with $1p$-$1h$ and $2p$-$2h$ clusters and a non-iterative treatment of $3p$-$3h$ clusters is as accurate as the more demanding CI approach truncated at the $4p$-$4h$ level. [Preview Abstract] |
Tuesday, April 17, 2007 11:33AM - 11:45AM |
X16.00005: Alpha, Proton and Ion Decay Made Possible by Variable Nuclear Barrier Heights Stewart Brekke In a previous soon to be revised paper due to nuclear vibration the Coulomb barrier height was found to be a variable with a value given by KE needed = $kQ(1)Q(2)/[12A^2cos^{22}\backslash pift]^{1/2}$. The range of the Coulomb barrier height was infinitely high to a low of $kQ(1)Q(2)/2[3]^2$ with an RMS value of $kQ(1)Q(2)/(6)^{1/2}$ when using a three dimensional nuclear oscillator for the motion of the nucleus. Since the value of the Coulomb barrier varies with time and amplitude of nuclear motion, the wall of the nuclear well and Coulomb barrier can be high and low. As the decaying particle such as an alpha, proton, or ion bounces against the nuclear wall, when the wall of the nuclear well and Coulomb barrier are sufficiently low at the same time nuclear decay can takeplace. This combination can be extremely fast or extremely slow. This physical phenomenon accounts for nuclear decay without the artifice of tunneling. [Preview Abstract] |
Tuesday, April 17, 2007 11:45AM - 11:57AM |
X16.00006: Checker Board Model Thedore Lach The Checker Board Model (CBM) is a 2D model of the nucleus that proposes that the synchronization of two outer rotating quarks in the nucleons accounts for magnetic moment of the nucleons and that the resulting magnetic flux couples (weaves) into the 2D checker board array structures and this 2D magnetic coupling in addition to electrostatic forces of the two rotating and one stationary quark accounts for the apparent strong nuclear force. The symmetry of the He nucleus helps explain why this 2D structure is stable. This model explain the mass of the proton and neutron, along with their magnetic moments and their absolute and relative sizes and predict the masses of two newly proposed quarks $^{(1)}$: the ``up'' and the ``dn'' quarks. Since the masses of the ``up'' and ``dn'' quark determined by the CBM (237.31 MeV and 42.392 MeV respectively) did not fit within the standard model as candidates for u and d, a new model (New Physics) had to be invented. The details of this new nuclear physics model can be found at: http://checkerboard.dnsalias.net/ (1). T.M. Lach, Checkerboard Structure of the Nucleus, Infinite Energy, Vol. 5, issue 30, (2000). (2). T.M. Lach, Masses of the Sub-Nuclear Particles, nucl-th/0008026, @http://xxx.lanl.gov/ [Preview Abstract] |
Tuesday, April 17, 2007 11:57AM - 12:09PM |
X16.00007: Renormalization of chiral NN potentials and Weinberg power counting Ruprecht Machleidt, David Entem In recent years, quantitative nucleon-nucleon (NN) potentials based upon chiral perturbation theory (ChPT) have been developed. All these potentials apply what is known as ``Weinberg power counting''. However, this renormalization scheme has been the subject of varying forms of criticism for more than a decade. Systematic investigations of the issue conducted to date have been restricted to only the leading order (LO) of ChPT. Since quantitative chiral NN potentials are constructed at next-to-next-to-next-to-leading (N3LO), it is necessary to investigate the power counting issue beyond LO, and ultimately at N3LO. We have launched such a program and will report the current status of our findings. [Preview Abstract] |
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