Search results for "SIP"
showing 10 items of 1280 documents
Kπ=8−isomers andKπ=2−octupole vibrations inN=150shell-stabilized isotones
2008
Isomers have been populated in {sup 246}Cm and {sup 252}No with quantum numbers K{sup {pi}}=8{sup -}, which decay through K{sup {pi}}=2{sup -} rotational bands built on octupole vibrational states. For N=150 isotones with (even) atomic number Z=94-102, the K{sup {pi}}=8{sup -} and 2{sup -} states have remarkably stable energies, indicating neutron excitations. An exception is a singular minimum in the 2{sup -} energy at Z=98, due to the additional role of proton configurations. The nearly constant energies, in isotones spanning an 18% increase in Coulomb energy near the Coulomb limit, provide a test for theory. The two-quasiparticle K{sup {pi}}=8{sup -} energies are described with single-pa…
One-quasiparticle States in the Nuclear Energy Density Functional Theory
2009
We study one-quasiproton excitations in the rare-earth region in the framework of the nuclear Density Functional Theory in the Skyrme-Hartree-Fock-Bogoliubov variant. The blocking prescription is implemented exactly, with the time-odd mean field fully taken into account. The equal filling approximation is compared with the exact blocking procedure. We show that both procedures are strictly equivalent when the time-odd channel is neglected, and discuss how nuclear alignment properties affect the time-odd fields. The impact of time-odd fields on calculated one-quasiproton bandhead energies is found to be rather small, of the order of 100-200 keV; hence, the equal filling approximation is suff…
Linear response of light deformed nuclei investigated by self-consistent quasiparticle random-phase approximation
2010
We present a calculation of the properties of vibrational states in deformed, axially-symmetric even-even nuclei, within the framework of a fully self-consistent quasiparticle random phase approximation (QRPA). The same Skyrme energy density and density-dependent pairing functionals are used to calculate the mean field and the residual interaction in the particle-hole and particle-particle channels. We have tested our software in the case of spherical nuclei against fully self-consistent calculations published in the literature, finding excellent agreement. We investigate the consequences of neglecting the spin-orbit and Coulomb residual interactions in QRPA. Furthermore we discuss the impr…
Gamow-Teller decay ofZn80: Shell structure and astrophysical implications
1988
Gamow-Teller \ensuremath{\beta} decay of $^{80}\mathrm{Zn}$ to levels in $^{80}\mathrm{Ga}$ has been calculated from a random-phase-approximation shell model with Nilsson model wave functions. The predicted features are compared to existing experimental results. Gross \ensuremath{\beta}-decay properties as well as quasiparticle structure indicate shape coexistence for $^{80}\mathrm{Ga}$. This result implies a rather rapid weakening of the shell strength far from \ensuremath{\beta} stability above $_{28}^{78}\mathrm{Ni}_{50}$. The nuclear properties of $^{80}\mathrm{Zn}$ as an astrophysical ``waiting-point'' nucleus suggest that the r-process scenario which is responsible for the solar r abu…
Deep Inelastic Lepton Scattering in Nuclei at x > 1 and the Nucleon Spectral Function
1995
The nuclear structure function F_2A(x) has been studied in the Bjorken limit for (l, l') scattering on nuclei in the region of x > 1 and was found to be very sensitive to the information contained in the nucleon spectral function in nuclei, particularly the correlations between momenta and energies in the region of large momenta. Calculations were done in a local density approximation using two different spectral functions for nuclear matter. Results are compared to those obtained for a spectral function which has been evaluated directly for the finite nucleus, ^{16}O, under consideration. For values of x around 1.5 and larger the quasiparticle contribution is negligible, thus stressing …
Event-by-event distributions of azimuthal asymmetries in ultrarelativistic heavy-ion collisions
2012
Relativistic dissipative fluid dynamics is a common tool to describe the space-time evolution of the strongly interacting matter created in ultrarelativistic heavy-ion collisions. For a proper comparison to experimental data, fluid-dynamical calculations have to be performed on an event-by-event basis. Therefore, fluid dynamics should be able to reproduce, not only the event-averaged momentum anisotropies, $$, but also their distributions. In this paper, we investigate the event-by-event distributions of the initial-state and momentum anisotropies $\epsilon_n$ and $v_n$, and their correlations. We demonstrate that the event-by-event distributions of relative $v_n$ fluctuations are almost eq…
Relative importance of second-order terms in relativistic dissipative fluid dynamics
2013
In Denicol et al., Phys. Rev. D 85, 114047 (2012), the equations of motion of relativistic dissipative fluid dynamics were derived from the relativistic Boltzmann equation. These equations contain a multitude of terms of second order in Knudsen number, in inverse Reynolds number, or their product. Terms of second order in Knudsen number give rise to non-hyperbolic (and thus acausal) behavior and must be neglected in (numerical) solutions of relativistic dissipative fluid dynamics. The coefficients of the terms which are of the order of the product of Knudsen and inverse Reynolds numbers have been explicitly computed in the above reference, in the limit of a massless Boltzmann gas. Terms of …
Complex-energy approach to sum rules within nuclear density functional theory
2015
The linear response of the nucleus to an external field contains unique information about the effective interaction, correlations, and properties of its excited states. To characterize the response, it is useful to use its energy-weighted moments, or sum rules. By comparing computed sum rules with experimental values, the information content of the response can be utilized in the optimization process of the nuclear Hamiltonian or EDF. But the additional information comes at a price: compared to the ground state, computation of excited states is more demanding. To establish an efficient framework to compute sum rules of the response that is adaptable to the optimization of the nuclear EDF an…
NUCLEAR MATRIX ELEMENTS FOR DOUBLE BETA DECAY
2008
The neutrinoless double beta (0νββ) decay of atomic nuclei plays a key role in the search for massive Majorana neutrinos and their mass scale. To extract the necessary information from the measured data the nuclear-structure effects have to be accounted for by computation of the associated nuclear matrix elements (NME's). In this article the NME's for the light-neutrino exchange mechanism are discussed. They are computed by using the proton-neutron quasiparticle random-phase approximation (pnQRPA). Recent developments in this field relate to the handling of the nucleon-nucleon short-range correlations and independent experimental probes of the wave functions relevant for the NME's.
Study of several double-beta-decaying nuclei using the renormalized proton-neutron quasiparticle random-phase approximation
1997
The renormalized proton-neutron quasiparticle random-phase approximation model (RQRPA) has been used to calculate double-\ensuremath{\beta}-decay matrix elements and associated transition half-lives for two-neutrino double \ensuremath{\beta} decay of parent nuclei ${}^{76}\mathrm{Ge},$ ${}^{78}\mathrm{Kr},$ ${}^{82}\mathrm{Se},$ ${}^{96}\mathrm{Zr},$ ${}^{106}\mathrm{Cd},$ and ${}^{130}\mathrm{Te}$ to the ground state and excited one- and two-phonon states of their daughter nuclei. The results are compared to ordinary proton-neutron QRPA and experiments. In addition, the violation of the Ikeda sum rule in the RQRPA is examined and discussed.