Search results for " Phase"
showing 10 items of 1862 documents
Generalization of the atomic random-phase-approximation method for diatomic molecules:N2photoionization cross-section calculations
2000
Partial and total photoionization cross sections of ${\mathrm{N}}_{2}$ molecule are calculated using the generalization of the random-phase approximation (RPA) which earlier has been successfully applied to the description of the atomic photoionization processes. According to this method, at first the Hartree-Fock (HF) ground-state wave functions are calculated in prolate spheroidal coordinates using the fixed-nuclei approximation. With their help the zero order basis set of single particle Hartree-Fock wave functions containing both discrete excited states and continuous spectrum is calculated in the field of a frozen core of a singly charged ion. The calculations are performed for all fou…
Neutral-current supernova-neutrino cross sections for Pb204,206,208 calculated by Skyrme quasiparticle random-phase approximation
2019
The present work constitutes a detailed study of neutral-current (NC) supernova-neutrino scattering off the stable even-even lead isotopes Pb204,206,208. This is a continuation of our previous work [Almosly et al., Phys. Rev. C. 94, 044614 (2016)10.1103/PhysRevC.94.044614] where we investigated charged-current processes on the same nuclei. As in the previous work, we have adopted the quasiparticle random-phase approximation (QRPA) as the theory framework and use three different Skyrme interactions to build the involved nuclear wave functions. We test the Skyrme forces by computing the location of the lowest-order isovector spin-multipole giant resonances and comparing with earlier calculati…
RESONANT ACTIVATION AND NOISE ENHANCED STABILITY IN JOSEPHSON JUNCTIONS
2005
We investigate the interplay of two noise-induced effects on the temporal characteristics of short overdamped Josephson junctions in the presence of a periodic driving. We find that: (i) the mean life time of superconductive state has a minimum as a function of driving frequency, and near the minimum it actually does not depend on the noise intensity (resonant activation phenomenon); (ii) the noise enhanced stability phenomenon increases the switching time from superconductive to the resistive state. As a consequence there is a suitable frequency range of clock pulses, at which the noise has a minimal effect on pulse propagation in RSFQ electronic devices.
Noise induced effects in overdamped Josephson junction in the presence of colored noise
2007
We analyze the role of the correlated fluctuations, with a correlation time τc, in the dynamics of an overdamped Josephson junction in the presence of a periodic driving signal.
Configurational entropy of microemulsions : The fundamental length scale
1993
Phenomenological models have been quite successful in characterizing both the various complex phases and the corresponding phase diagrams of microemulsions. In some approaches, e.g., the random mixing model (RMM), the lattice parameter is of the order of the dimension of an oil or water domain and has been used as a length scale for computing a configurational entropy, the so‐called entropy of mixing, of the microemulsion. In the central and material section of this paper (Sec. III), we show that the fundamental length scale for the calculation of the entropy of mixing is of the order of the cube root of the volume per molecule—orders of magnitude smaller than the dimension of such a domain…
RPA in wavefunction representation
1992
The RPA is formulated in subspaces of coordinate-like and momentum-like I ph operators. This allows to embed a large class of approximative schemes into a generalized RPA treatment. We give a detailed formulation in terms of wavefunctions in coordinate space which is ideally suited to practical programming. In particular, we work out the reduction to spherical tensors in the case of spherical symmetry which is most often the starting point in finite Fermion systems.
Neutrinoless double beta decays of 106Cd revisited
2011
Abstract Neutrinoless double beta ( 0 ν 2 β ) decays of 106 Cd are studied for the transitions to the ground state, 0 gs + , and 0 + excited states in 106 Pd by using realistic many-body wave functions calculated in the framework of the quasiparticle random-phase approximation and its extensions. Effective, G-matrix-based nuclear forces are used in large single-particle model spaces. Both the β + β + and β + EC channels of the 0 ν 2 β decay are discussed and half-lives are computed. Particular attention is devoted to the study of the detectability of the resonant neutrinoless double electron capture ( R 0 ν ECEC ) process in 106 Cd. The calculations of the present article constitute the thu…
Theoretical interpretation of the Ds+→π+π0η decay and the nature of a0(980)
2020
Abstract In a recent paper [1] , the BESIII Collaboration reported the so-called first observation of pure W-annihilation decays D s + → a 0 + ( 980 ) π 0 and D s + → a 0 0 ( 980 ) π + . The measured absolute branching fractions are, however, puzzlingly larger than those of other measured pure W-annihilation decays by at least one order of magnitude. In addition, the relative phase between the two decay modes is found to be about 180 degrees. In this letter, we show that all these can be easily understood if the a 0 ( 980 ) is a dynamically generated state from K ¯ K and πη interactions in coupled channels. In such a scenario, the D s + decay proceeds via internal W emission instead of W-an…
Conceptual design and performance study for the first implementation of AGATA at the in-flight RIB facility of GSI
2012
Abstract The main objective of the Advanced GAmma Tracking Array (AGATA) is the investigation of the structure of exotic nuclei at the new generation of RIB facilities. As part of the preparatory phase for FAIR-NUSTAR, AGATA is going to be installed at the FRS fragmentation facility of the GSI centre for an experimental campaign to be performed in 2012 and 2013. Owing to its γ - ray tracking capabilities and the envisaged enhancement in resolving power, a series of in-flight γ - ray spectroscopy experiments are being planned. The present work describes the conceptual design of this first implementation of AGATA at GSI-FRS, and provides information about the expected performance figures. Acc…
Electromagnetic properties of some positive parity dipole states described in terms of quadrupole and octupole interacting bosons
1990
The first three positive parity dipole states predicted by a phenomenological quadrupole-octupole boson Hamiltonian are extensively studied. Their coupling to the neighboring positive and negative parity states, due to the {ital M}1 and {ital E}{lambda} ({lambda}=1,3) transitions, respectively, are considered. Special attention is paid to the lowest two states which are of collective {ital M}1 nature. The signature which distinguishes them from the {ital M}1 state describing the scissors mode is also discussed.