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Recently, Bailey et al. performed iron opacity measurements on the Z machine at Sandia National Laboratory in conditions close to the ones of the base of the convective zone of the Sun. Such experiments have raised questions about the…

Atomic Physics · Physics 2018-04-04 Jean-Christophe Pain

Seismology of stars is strongly developing. To address this question we have formed an international collaboration OPAC to perform specific experimental measurements, compare opacity calculations and improve the opacity calculations in the…

There are two alternative methods used in literature to calculate the incoherent part of the spectrum of light scattered by an atomic system. In the first, one calculates the spectrum of the total light scattered by the system and obtains…

Quantum Physics · Physics 2015-05-13 Z. Ficek

The Petersen diagram is a frequently used tool to constrain model parameters such as metallicity of radial double-mode pulsators. In this diagram the period ratio of the radial first overtone to the fundamental mode, P_1/P_0, is plotted…

Astrophysics · Physics 2008-11-26 P. Lenz , A. A. Pamyatnykh , M. Breger

In this article, we examine different approaches for calculating low frequency opacities in the warm dense matter regime. The relevance of the average-atom approximation and of different models for calculating opacities, such as the Ziman…

Plasma Physics · Physics 2025-04-04 Mikael Tacu , Jean-Christophe Pain , Matthias Pautard , Christophe Blancard

For high temperatures and densities, stellar opacities obtained from the Opacity Project (OP) were smaller than those obtained from the OPAL project. Iglesias and Rogers [Ap.J. v443, 469 (1995)] suggested that the discrepancy was due to the…

Astrophysics · Physics 2009-11-10 N. R. Badnell , M. J. Seaton

Opacity determines radiation transport through material media. In a plasma source the primary contributors to atomic opacity are bound-bound line transitions and bound-free photoionization into the continuum. We review the theoretical…

Solar and Stellar Astrophysics · Physics 2023-03-08 Anil Pradhan

The computation of radiative opacity or emissivity of hot dense matter is a challenging task. It requires accounting for an immense number of energy levels and lines across various excitation and ionization states. Whether in local…

Atomic Physics · Physics 2025-09-03 Jean-Christophe Pain , Djamel Benredjem

We apply a new method "force enhanced atomic refinement" (FEAR) to create a computer model of amorphous silicon (a-Si), based upon the highly precise X-ray diffraction experiments of Laaziri et al. The logic underlying our calculation is to…

Materials Science · Physics 2016-12-28 Anup Pandey , Parthapratim Biswas , Bishal Bhattarai , D. A. Drabold

Accurate atomic data are essential for opacity calculations and for abundance analyses of the Sun and other stars. The aim of this work is to provide accurate and extensive results of energy levels and transition data for C I - IV. The…

Atomic Physics · Physics 2021-02-03 W. Li , A. M. Amarsi , A. Papoulia , J. Ekman , P. Jönsson

We presented a new method for measuring the squares of the amplitudes and phases of partial vortex-beams in a complex beam array in real time. The method is based on measuring the high-order intensity moments and analyzing the solutions of…

Optics · Physics 2018-12-05 A. Volyar , M. Bretsko , Ya. Akimova , Yu. Egorov

Coalescence of binary neutron star give rise to electromagnetic emission, kilonova, powered by radioactive decays of r-process nuclei. Observations of kilonova associated with GW170817 provided unique opportunity to study the heavy element…

Solar and Stellar Astrophysics · Physics 2019-02-13 Gediminas Gaigalas , Daiji Kato , Pavel Rynkun , Laima Radziute , Masaomi Tanaka

We investigate the effect of resonances in photoionization and recombination cross sections computed using the R-matrix method. Photoionization and recombination rates derived from high-resolution cross sections for oxygen ions are compared…

Astrophysics · Physics 2009-11-10 Franck Delahaye , Sultana N. Nahar , Anil K Pradhan , Hong Lin Zhang

The familiar tools of Fourier analysis and Fisher matrices are applied to derive the uncertainties on photometric, astrometric, and weak-lensing measurements of stars and galaxies in real astronomical images. Many effects or functions that…

Astrophysics · Physics 2007-05-23 Gary Bernstein

A method is described for using resonant x-ray scattering to separately quantify the charge (valence) modulation and the strain wave associated with a charge density wave. The essence of the method is a separation of the atomic form factor…

Strongly Correlated Electrons · Physics 2010-11-09 P. Abbamonte

The effect of autoionizing resonances in atomic systems and processes is reviewed. Theoretical framework for treating resonances in the coupled channel approximation using the R-matrix method, as well as approximations related to plasma…

High Energy Astrophysical Phenomena · Physics 2024-05-16 Anil Pradhan

We define and measure the ratio (R) of the vector ac-Stark effect (or light shift) in the 6S_1/2 and 5D_3/2 states of a single trapped barium ion to 0.2% accuracy at two different off-resonant wavelengths. We earlier found R = -11.494(13)…

Atomic Physics · Physics 2009-11-13 J. A. Sherman , A. Andalkar , W. Nagourney , E. N. Fortson

Nowadays for measurement of refractive index of nanomaterials usually spectro-photometric and mechanical methods are used which are expensive and indirect. In this paper for measuring these parameters of zinc oxide nanomaterial with two…

Instrumentation and Detectors · Physics 2019-02-05 Fatemeh Jamal , Fatemeh Ahmadi , Mohammad Khanzadeh , Saber Malekzadeh

Optical cavities are an enabling technology of modern quantum science: from their essential role in the operation of lasers, to applications as fly-wheels in atomic clocks and interaction-enhancing components in quantum optics experiments,…

Optics · Physics 2021-08-04 Matt Jaffe , Lukas Palm , Claire Baum , Lavanya Taneja , Jonathan Simon

A new numerical method is introduced for calculating the polarizability of an arbitrary dielectric object with position dependent complex permittivity. Three separate numerical approaches are provided to calculate the dipole moment of a…

Materials Science · Physics 2022-03-18 Daniel B. Murray , Caleb H. Netting , Robin D. Mercer , Lucien Saviot