Bulletin of the American Physical Society
APS April Meeting 2013
Volume 58, Number 4
Saturday–Tuesday, April 13–16, 2013; Denver, Colorado
Session G13: Nuclear Theory |
Hide Abstracts |
Sponsoring Units: DNP Chair: Simon Capstick, Florida State University Room: Plaza Court 2 |
Sunday, April 14, 2013 8:30AM - 8:42AM |
G13.00001: Manifestations of triaxiality in nuclear spectrum and in electromagnetic transitions Volha Abramkina, Alexander Volya In this presentation we discuss how the triaxiality and its properties can be identified and studied using the nuclear spectrum and electromagnetic transitions between the low-lying states. The methods of evaluating triaxiality are tested using systems with random interactions and using the nuclear shell-model. We apply the developed techniques in studies of realistic nuclei.We treat the moment of inertia tensor independently from the electric quadrupole tensor. This allows an independent evaluation of the K-mixing angle and the Hill-Wheeler triaxiality shape parameter. The connection between the inertial parameters and the shape of the charge distribution are compared with those predicted by the commonly used models of the rigid rotor (the Davydov-Filippov model) and the deformed liquid drop. [Preview Abstract] |
Sunday, April 14, 2013 8:42AM - 8:54AM |
G13.00002: Critical scaling of excited nuclear systems from quantum fluctuations Justin Mabiala At finite temperatures and low densities, nuclei may undergo a phase transition similar to a liquid-gas phase transition. Temperature is the control parameter while density and pressure are the conjugate variables. Thermodynamic properties of fragmenting systems formed in the reactions 64Zn$+$64Zn, 64Ni$+$64Ni and 70Zn$+$70Zn at beam energy of 35 MeV/nucleon were studied. Temperatures and densities were derived from a recent quantum method which is based on fluctuations in the fragment momentum and fragment multiplicity distributions of light fermions. The pressures were determined from the grand partition function of Fisher's model. Critical scaling of measured quantities is found for the first time for fragmenting systems that differ in proton-neutron asymmetries. These results which account for an experimental signature of a nuclear phase transition will be presented. [Preview Abstract] |
Sunday, April 14, 2013 8:54AM - 9:06AM |
G13.00003: Odd\_J Pairing Interaction Larry Zamick, Alberrto Escuderos We consider in the g9/2 shell an interaction which acts only when a neutron and proton act in a state with J=Jmax=2j =9. We uses the abbreviated notation for a unitary 9j-symbol U(Jx Jp Jn J)= $<$(jj)9 (jj)Jx | (jj)Jp (jj)Jn $>$J . The Pauli principle demands that J p and Jn are both even. The matrix element of the hamiltonian is E(9) {*} SJx U(Jx, Jp Jn J) U(Jx Jp\textquoteright{} Jn\textquoteright{} J). For J=0 and 1 the Hamiltonian is a single separable term and the lowest eigenfunctions are the components of unitary 9j symbols, $\surd{2}$ U(9 Jp Jn 0) for J=0 and 2 U(8 Jp Jn 1) for J=1. These states have isospin T=0 . For J=2 and higher the Hamiltonian is no longer separable but there still some simple states. For J=2 there is a T=1 state 2U(8 Jp Jn 2 ) and for J=3 T=0 , 2U (7 Jp Jn 3) . For all these Jx serves as a good quantum number. The 2 lowest J=2 T=0 states are admixtures of $\surd{2}$ U(9 Jp Jn 2) and 2 U(7 Jp Jn 2) but the coupling is so weak that these are almost separate eigenstates with quantum numbers Jx=9 and Jx=7 respectively. The coupling matrix element is -1/2 U (9 9 7 2)= 0.00009113. The normalizations of the 2 admixed states are respectively such that N-2 =1/2- U(9 9 9 2) = 0.499993950935 and 1/4- 1/2 U(7 9 7 2)= 0.250376267385. [Preview Abstract] |
Sunday, April 14, 2013 9:06AM - 9:18AM |
G13.00004: Fusion of neutron-rich systems using time-dependent density-constrained DFT Volker Oberacker, A.S. Umar In connection with experiments at Radioactive Ion Beam Facilities, we study fusion reactions with a new approach [1] which is based on a time-dependent density-constrained density functional theory (DFT). The only input is the Skyrme NN interaction, there are no adjustable parameters. We calculate heavy-ion interaction potentials $V(R)$, mass parameters $M(R)$, and total fusion cross sections. Some of the effects naturally included in these calculations are: neck formation, mass exchange, internal excitations, deformation effects, as well as nuclear alignment for deformed systems. Results will be presented for low-energy fusion reactions of $^{12}$C+$^{16,24}$O and for $^{16,24}$O+$^{16,24,28}$O which occur in the crust of neutron stars [2]. Finally, we will discuss fusion with neutron-rich halo nuclei, in particular $^{11}$Li+$^{208}$Pb.\\[4pt] [1] Umar and Oberacker, PRC 74, 021601(R) (2006)\\[0pt] [2] Umar, Oberacker, and Horowitz, PRC 85, 055801 (2012) [Preview Abstract] |
Sunday, April 14, 2013 9:18AM - 9:30AM |
G13.00005: Nuclear Structure: Going Beyond Standard Methods Jennifer Glick, Vladimir Zelevinsky Many features of nuclear structure in medium and heavy nuclei are traditionally described by methods borrowed from macroscopic many-body physics, such as random phase approximation (RPA), or pairing theory according to BCS and HFB. These methods are routinely used when the exact large-scale diagonalization of the Hamiltonian matrix is impossible. The approximations inherently present in such methods, being appropriate in macroscopic physics, may introduce substantial errors for mesoscopic systems, such as atomic nuclei or cold atoms in traps. We develop the theory of collective motion based on exact particle number conservation. The first applications to the ground state physics (collaboration with A. Volya) demonstrated that such an approach avoids well known deficiencies of the standard treatment. Now we apply the method to low-lying collective excitations which are even more sensitive to conservation laws. The new RPA version is reduced to the set of recurrence relations for neighboring nuclei. We show that it is especially important for the cases of strong anharmonicity and in the vicinity of the instability point. Other examples are discussed where the advance beyond standard approaches gives new physical results. [Preview Abstract] |
Sunday, April 14, 2013 9:30AM - 9:42AM |
G13.00006: QRPA calculations of Giant Monopole Resonances Paolo Avogadro, Carlos Bertulani, Takashi Nakatsukasa We present calculations of giant monopole resonances obtained with a fully self consistent spherical quasiparticle random phase approximation (QRPA) on top of a Hartree-Fock-Bogoliubov (HFB) code. These results are compared with the most recent experiments on Sn and Cd isotopes to try to shed light on the abnormal softness of these isotopes. In the particle hole channel we use Skryme functionals while in the pairing channel we make use of density dependent contact interactions. The density dependence of the pairing interaction is explicitly taken into account. [Preview Abstract] |
Sunday, April 14, 2013 9:42AM - 9:54AM |
G13.00007: A New Electromagnetic Cabibbo-Kobayshi-Maskawa Quark Mixing Matrix Thomas Ward A new electromagnetic neutral-current quark mixing matrix $V_{CKM}^{EM}$, analog to the well-known Cabibbo-Kobayashi-Maskawa (CKM) weak charge-current matrix $V_{CKM}^{Weak}$, is proposed to account for the strange quark content of the neutron and proton and part of the anomalous axial vector magnetic moments. A phenomenological formulation of the magnetic dipole moments that include strange quark contributions is shown to account for the magnetic moments at an uncertainty level of 0.3 ppm. The EM-CKM matrix is shown to be equivalent to the weak-CKM matrix following an EM to weak gauge symmetry transformation, demonstrating the universality of the CKM quark mixing matrix. The role of strange quark isospin symmetry breaking (ISB) terms are briefly discussed within the framework of conventional nuclear physics of two-body NN M1 interactions in charge independence breaking (CIB), charge symmetry breaking (CSB), the photo-disintegration of the deuteron and radiative \textit{np} capture. [Preview Abstract] |
Sunday, April 14, 2013 9:54AM - 10:06AM |
G13.00008: Polarization Operator in a Theory of Massless Fermions with Superfluidity Sajib Barman, Vivian Incera A QCD inspired effective theory of fermions has been applied to study superfluidity. We calculate the polarization operator of a theory of fermions at finite density with fermion-fermion condensate. In this theory color degrees of freedom and external magnetic fields are absent. The diagram of the polarization operator has vertex with scalar fields and is called Yukawa vertex. We start from the full fermion propagator found in the model of massless fermions and used the Nambu-Jona-Lasinio model to calculate the polarization operator. Finally the influence of the medium in the polarization properties is discussed. [Preview Abstract] |
Sunday, April 14, 2013 10:06AM - 10:18AM |
G13.00009: Exotic nuclear structure and origin of the heavy nuclei with covariant density functional theory Jie Meng The covariant density functional theory with a minimal number of parameters allows a very successful description of nuclear ground state as well as excited state properties all over the nuclear chart. Firstly in this talk, its recent progresses, including the deformed relativistic Hartree-Bogoliubov theory in continuum and the fully self-consistent proton-neutron quasiparticle random phase approximation newly developed based on the relativistic Hartree-Fock-Bogoliubov theory, are briefly reviewed. The halo phenomenon in deformed weakly bound nuclei and the beta-decay half-lives of the neutron-rich nuclei are discussed. With mass table and the beta-decay half-lives of the neutron-rich nuclei obtained, the speeding-up of the r-matter flow is suggested which thus produces higher r-process abundances of elements with A $\sim$ 140 and help us to understand the origin of heavy elements in the universe. The constraints of nuclear mass model and astrophysical condition by the observed Solar abundance are discussed. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2021 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
1 Research Road, Ridge, NY 11961-2701
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700