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Electromagnetic radiation from blazar jets often displays strong variability, extending from radio to $\gamma$-ray frequencies. In a few cases, this variability has been characterized using Fourier time lags, such as those detected in the…

High Energy Astrophysical Phenomena · Physics 2016-06-29 Tiffany R. Lewis , Peter A. Becker , Justin D. Finke

We show that strongly photoexcited graphene monolayers with 35fs pulses quasi-instantaneously build up a broadband, inverted Dirac fermion population. Optical gain emerges and directly manifests itself via a negative optical conductivity…

Mesoscale and Nanoscale Physics · Physics 2019-03-12 T. Li , L. Luo , M. Hupalo , J. Zhang , M. C. Tringides , J. Schmalian , J. Wang

We perform a frequency-resolved analysis of electron dynamics in solids to obtain microscopic insight into linear and nonlinear optical phenomena. For the analysis, we first compute the electron dynamics under optical electric fields and…

Materials Science · Physics 2023-07-25 Shunsuke A. Sato

The prompt emission mechanism of gamma-ray bursts (GRBs) is still unclear, and the time-resolved spectral analysis of GRBs is a powerful tool for studying their underlying physical processes. We performed a detailed time-resolved spectral…

High Energy Astrophysical Phenomena · Physics 2024-01-29 Wan-Kai Wang , Wei Xie , Zhi-Fu Gao , Shuo Xiao , Ai-Jun Dong , Bin Zhang , Qi-Jun Zhi

The emission times of laser-triggered electrons from a sharp tungsten tip are directly characterized under ultrafast, near-infrared laser excitation at Keldysh parameters $6.6< \gamma < 19.1$. Emission delays up to 10 fs are observed, which…

Electron group velocity for graphene under uniform strain is obtained analitically by using the Tight-Binding approx- imation. Such closed analytical expressions are useful in order to calculate electronic, thermal and optical properties of…

Mesoscale and Nanoscale Physics · Physics 2016-02-17 Wilfrido A. Gómez-Arias , Gerardo G. Naumis

Describing the behaviour of strongly interacting particles in the presence of disorder is among the most challenging problems in quantum many-body physics. The controlled setting of cold atom experiments provides a new avenue to address…

High-energy solar flares have shown to have at least two distinct phases: prompt-impulsive and delayed-gradual. Identifying the mechanism responsible for accelerating the electrons and ions and the site at which it occurs during these two…

Solar and Stellar Astrophysics · Physics 2021-09-29 Melissa Pesce-Rollins , Nicola Omodei , Vahe' Petrosian , Francesco Longo

Photons emitted from high-energy electron beam interactions with high-field systems, such as the upcoming FACET-II experiments at SLAC National Accelerator Laboratory, may provide deep insight into the electron beam's underlying dynamics at…

Accelerator Physics · Physics 2024-09-05 M. Yadav , M. H. Oruganti , B. Naranjo , G. Andonian , Ö. Apsimon , C. P. Welsch , J. B. Rosenzweig

Smooth, highly accurate analytical representations of Fermi-Dirac (FD) integral combinations important in free-energy density functional calculations are presented. Specific forms include those that occur in the local density approximation…

Computational Physics · Physics 2015-04-21 Valentin V. Karasiev , Debajit Chakraborty , S. B. Trickey

The Fermi-LAT data accumulated over 7 years of {\gamma}-ray observations, together with the high resolution gas (CO & HI) and the dust opacity maps, are used to study the emissivity of {\gamma}-rays induced by interactions of cosmic rays…

High Energy Astrophysical Phenomena · Physics 2016-06-22 Rui-zhi Yang , Felix Aharonian , Carmelo Evoli

In this paper, we discuss the light-curve features of various flaring scenarios in a time-dependent leptonic model for low-frequency-peaked blazars. The quasar 3C273 is used as an illustrative example. Our code takes into account Fermi-II…

High Energy Astrophysical Phenomena · Physics 2014-04-21 Christopher Diltz , Markus Boettcher

We propose a new concept of an electron source for ultrafast electron diffraction with sub-10~fs temporal resolution. Electrons are generated in a laser-plasma accelerator, able to deliver femtosecond electron bunches at 5 MeV energy with…

Accelerator Physics · Physics 2016-04-20 J. Faure , B. van der Geer , B. Beaurepaire , G. Gallé , A. Vernier , A. Lifschitz

We investigate the quantum dynamics of fermionic particles interacting with a laser field in a gaseous medium, in the regime of inelastic diffraction scattering on the phase lattice of a slowed travelling wave, below the critical field of…

Optics · Physics 2025-07-04 H. K. Avetissian , G. F. Mkrtchian

The electronic and nuclear dynamics in methanol, following 156~nm photoexcitation, are investigated by combining a detailed analysis of time-resolved photoelectron spectroscopy experiments with electronic structure calculations. The…

A new type of disorder-driven electronic percolation transition is found for two-dimensional electron gas (2DEG), based on a quantum cellular automaton model. This transition is shown to be accompanied with a metal-insulator transition, as…

Statistical Mechanics · Physics 2018-10-17 M. N. Najafi

We explore the influence of the nanoporous structure on the thermal relaxation of electrons and holes excited by ultrashort laser pulses ($\sim 7$ fs) in thin gold films. Plasmon decay into hot electron-hole pairs results in the generation…

A simple table-size ECR plasma generator operates in the ATOMKI without axial magnetic trap and without any particle extraction tool. Radial plasma confinement is ensured by a NdFeB hexapole. The table-top ECR is a simplified version of the…

Plasma Physics · Physics 2015-01-29 R. Rácz , S. Biri , P. Hajdu , J. Pálinkás

Using transient absorption (TA) microscopy as a hot electron thermometer we show disorder-assisted acoustic-phonon supercollisions (SCs) best describes the rate-limiting relaxation step in graphene over a wide range of lattice temperatures…

Materials Science · Physics 2013-10-25 Matt W. Graham , Su-Fei Shi , Zenghui Wang , Daniel C. Ralph , Jiwoong Park , Paul L. McEuen

We report ultrafast transient-grating measurements of crystals of the three-dimensional Dirac semimetal cadmium arsenide, Cd3As2, at both room temperature and 80 K. After photoexcitation with 1.5-eV photons, charge-carriers relax by two…