5,321 research outputs found

    No-Core Shell Model for Nuclear Systems with Strangeness

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    We report on a novel ab initio approach for nuclear few- and many-body systems with strangeness. Recently, we developed a relevant no-core shell model technique which we successfully applied in first calculations of lightest Λ\Lambda hypernuclei. The use of a translationally invariant finite harmonic oscillator basis allows us to employ large model spaces, compared to traditional shell model calculations, and use realistic nucleon-nucleon and nucleon-hyperon interactions (such as those derived from EFT). We discuss formal aspects of the methodology, show first demonstrative results for Λ3{}_{\Lambda}^3H, Λ4{}_{\Lambda}^4H and Λ4{}^4_\LambdaHe, and give outlook.Comment: 4 pages, 3 figures; Proceedings of the 22nd European Conference on Few Body Problems in Physics, 9 - 13 September, 2013, Cracow, Polan

    Ab Initio Treatment of Collective Correlations and the Neutrinoless Double Beta Decay of 48^{48}Ca

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    Working with Hamiltonians from chiral effective field theory, we develop a novel framework for describing arbitrary deformed medium-mass nuclei by combining the in-medium similarity renormalization group with the generator coordinate method. The approach leverages the ability of the first method to capture dynamic correlations and the second to include collective correlations without violating symmetries. We use our scheme to compute the matrix element that governs the neutrinoless double beta decay of 48^{48}Ca to 48^{48}Ti, and find it to have the value 0.610.61, near or below the predictions of most phenomenological methods. The result opens the door to ab initio calculations of the matrix elements for the decay of heavier nuclei such as 76^{76}Ge, 130^{130}Te, and 136^{136}Xe.Comment: 6 pages, 4 figures and 1 table. supplementary material included. version to be publishe

    Logarithmic behavior of degradation dynamics in metal--oxide semiconductor devices

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    In this paper the authors describe a theoretical simple statistical modelling of relaxation process in metal-oxide semiconductor devices that governs its degradation. Basically, starting from an initial state where a given number of traps are occupied, the dynamics of the relaxation process is measured calculating the density of occupied traps and its fluctuations (second moment) as function of time. Our theoretical results show a universal logarithmic law for the density of occupied traps ˉϕ(T,EF)(A+Blnt)\bar{} \sim \phi (T,E_{F}) (A+B \ln t), i.e., the degradation is logarithmic and its amplitude depends on the temperature and Fermi Level of device. Our approach reduces the work to the averages determined by simple binomial sums that are corroborated by our Monte Carlo simulations and by experimental results from literature, which bear in mind enlightening elucidations about the physics of degradation of semiconductor devices of our modern life

    The influence of oscillations on energy estimates for damped wave models with time-dependent propagation speed and dissipation

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    The aim of this paper is to derive higher order energy estimates for solutions to the Cauchy problem for damped wave models with time-dependent propagation speed and dissipation. The model of interest is \begin{equation*} u_{tt}-\lambda^2(t)\omega^2(t)\Delta u +\rho(t)\omega(t)u_t=0, \quad u(0,x)=u_0(x), \,\, u_t(0,x)=u_1(x). \end{equation*} The coefficients λ=λ(t)\lambda=\lambda(t) and ρ=ρ(t)\rho=\rho(t) are shape functions and ω=ω(t)\omega=\omega(t) is an oscillating function. If ω(t)1\omega(t)\equiv1 and ρ(t)ut\rho(t)u_t is an "effective" dissipation term, then L2L2L^2-L^2 energy estimates are proved in [2]. In contrast, the main goal of the present paper is to generalize the previous results to coefficients including an oscillating function in the time-dependent coefficients. We will explain how the interplay between the shape functions and oscillating behavior of the coefficient will influence energy estimates.Comment: 37 pages, 2 figure

    New supersymmetric quartet of nuclei in the A=190 mass region

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    We present evidence for a new supersymmetric quartet in the A=190 region of the nuclear mass table. New experimental information on transfer and neutron capture reactions to the odd-odd nucleaus 194 Ir strongly suggests the existence of a new supersymmetric quartet, consisting of the 192,193 Os and 193,194 Ir nuclei. We make explicit predictions for the odd-neutron nucleus 193 Os, and suggest that its spectroscopic properties be measured in dedicated experiments.Comment: 5 pages, 4 figures, updated figures and revised text, Physical Review C, Rapid Communication, in pres

    Attosecond control of electron dynamics in carbon monoxide

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    Laser pulses with stable electric field waveforms establish the opportunity to achieve coherent control on attosecond timescales. We present experimental and theoretical results on the steering of electronic motion in a multi-electron system. A very high degree of light-waveform control over the directional emission of C+ and O+ fragments from the dissociative ionization of CO was observed. Ab initio based model calculations reveal contributions to the control related to the ionization and laser-induced population transfer between excited electronic states of CO+ during dissociation

    New supersymmetric quartet of nuclei in the A=190 mass region

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    We present evidence for a new supersymmetric quartet in the A=190 region of the nuclear mass table. New experimental information on transfer and neutron capture reactions to the odd-odd nucleaus 194 Ir strongly suggests the existence of a new supersymmetric quartet, consisting of the 192,193 Os and 193,194 Ir nuclei. We make explicit predictions for the odd-neutron nucleus 193 Os, and suggest that its spectroscopic properties be measured in dedicated experiments.Comment: 5 pages, 4 figures, updated figures and revised text, Physical Review C, Rapid Communication, in pres
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