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An implicit method for radiative transfer in SPH is described. The diffusion approximation is used, and the hydrodynamic calculations are performed by a fully three--dimensional SPH code. Instead of the energy equation of state for an ideal…

Astrophysics · Physics 2009-11-11 Serge Viau , Pierre Bastien , Seung-Hoon Cha

The nuclear reaction e+p+d -----> He3 + e is considered at thermonuclear energies. The motion of the electron is treated within the adiabatic approximation and the pd scattering state is constructed in the form of an antisymmetrized product…

Nuclear Theory · Physics 2009-10-30 S. A. Rakityansky , S. A. Sofianos , L. L. Howell , M. Braun , V. B. Belyaev

Radiation reaction (but, more generally, fluctuations and dissipation) occurs when a system interacts with a heat bath, a particular case being the interaction of an electron with the radiation field. We have developed a general theory for…

Quantum Physics · Physics 2015-06-04 R. F. O'Connell

A formal derivation is presented of the energy transfer rate between radiation and matter due to the scattering of an isotropic distribution of resonant photons. The derivation is developed in the context of the two-level atom in the…

Astrophysics · Physics 2010-04-29 Avery Meiksin

We report a numerical calculation of the two-photon absorption coefficient of electrons in a binding potential using the real-time real-space higher-order difference method. By introducing random vector averaging for the intermediate state,…

Materials Science · Physics 2009-10-31 Yoshiyuki Kurokawa , Shintaro Nomura , Tadashi Takemori , Yoshinobu Aoyagi

An efficient algorithm for calculating radiative transfer on massively parallel computers using domain decomposition is presented. The integral formulation of the transfer equation is used to divide the problem into a local but…

Astrophysics · Physics 2007-05-23 T. Heinemann , W. Dobler , A. Nordlund , A. Brandenburg

We demonstrate a method to reduce number fluctuations in an ultracold atomic sample using real-time feedback. By measuring the Faraday rotation of an off-resonant probe laser beam with a pair of avalanche photodetectors in a polarimetric…

Quantum Gases · Physics 2021-09-17 R. Thomas , J. S. Otto , M. Chilcott , A. B. Deb , N. Kjærgaard

A recoil coincidence technique has been applied to measure the alpha-decay branching ratios of near-threshold states in 19Ne. Populating these states using the (p,t) reaction in inverse kinematics, we detected the recoils and their decay…

Transfer reactions are a powerful probe of the properties of atomic nuclei. When used in inverse kinematics with radioactive ion beams they can provide detailed information on the structure of exotic nuclei and can inform nucleosynthesis…

Nuclear Experiment · Physics 2013-03-29 Kate L. Jones

We apply estimation theory to a system formed by two interacting trapped ions. By using the Fisher matrix formalism, we introduce a simple scheme for estimation of the temperature of the longitudinal vibrational modes of the ions. We use…

Quantum Physics · Physics 2022-05-26 O. P. de Sá Neto , H. A. S. Costa , G. A. Prataviera , M. C. de Oliveira

A general method for the direct evaluation of the temperature dependence of the quantum-mechanical reaction rate constant in many-dimensional systems is described. The method is based on the quantum instanton approximation for the rate…

Chemical Physics · Physics 2013-01-15 Marcin Buchowiecki , Jiri Vanicek

We study classical radiation fields at next-to-leading order using the methods of scattering amplitudes. The fields of interest to us are sourced when two massive, point-like objects scatter inelastically, and can be computed from one-loop…

High Energy Physics - Theory · Physics 2024-05-16 Asaad Elkhidir , Donal O'Connell , Matteo Sergola , Ingrid A. Vazquez-Holm

The thermal photon emission rate is determined by the spatially transverse, in-medium spectral function of the electromagnetic current. Accessing the spectral function using Euclidean data is, however, a challenging problem due to the…

High Energy Physics - Lattice · Physics 2022-12-13 Csaba Török , Marco Cè , Tim Harris , Ardit Krasniqi , Harvey B. Meyer , Samuel Ruhl

We compute the contribution to the two-body scattering angle of a specific class of interactions involving the exchange of gravitational radiative degrees of freedom, including the nonlinear memory process and square of radiation reaction…

General Relativity and Quantum Cosmology · Physics 2023-02-01 Gabriel Luz Almeida , Stefano Foffa , Riccardo Sturani

We study the astrophysical reaction rate for the formation of $^{9}$Be through the three body reaction $\alpha(\alpha n,\gamma)$. This reaction is one of the key reactions which could bridge the mass gap at A = 8 nuclear systems to produce…

Nuclear Theory · Physics 2009-11-07 K. Sumiyoshi , H. Utsunomiya , S. Goko , T. Kajino

Feedback traps are tools for trapping and manipulating single charged objects, such as molecules in solution. An alternative to optical tweezers and other single-molecule techniques, they use feedback to counteract the Brownian motion of a…

Statistical Mechanics · Physics 2017-01-24 Momčilo Gavrilov , John Bechhoefer

The direct measurement of the reaction or capture (fusion) cross section is a difficult task since it would require the measurement of individual cross sections of many reaction channels, and most of them could be reached only by specific…

Nuclear Theory · Physics 2015-06-18 V. V. Sargsyan , G. G. Adamian , N. V. Antonenko , P. R. S. Gomes

In this article we propose a numerical algorithm to compute the intensity and polarization of a polychromatic electromagnetic radiation crossing a medium with graded refractive index and modeled by the Vector Radiative Refractive Transfer…

Analysis of PDEs · Mathematics 2024-08-06 Olivier Pironneau

In this paper, a new fractional step method is proposed for simulating stiff and nonstiff chemically reacting flows. In stiff cases, a well-known spurious numerical phenomenon, i.e. the incorrect propagation speed of discontinuities, may be…

Computational Physics · Physics 2019-05-01 Jian-Hang Wang , Shucheng Pan , Xiangyu Y. Hu , Nikolaus A. Adams

In this paper, we present an inverse problem of identifying the reaction coefficient for time fractional diffusion equations in two dimensional spaces by using boundary Neumann data. It is proved that the forward operator is continuous with…

Numerical Analysis · Mathematics 2018-06-14 Xiaoyan Song , Guanghui Zheng , Lijian Jiang