Development Of Electromagnetic Cascades Research Articles

γ-Cascade V4: A semi-analytical code for modeling cosmological gamma-ray propagation

Since the universe is not transparent to gamma rays with energies above around one hundred GeV, it is necessary to account for the interaction of high-energy photons with intergalactic radiation fields in order to model gamma-ray propagation. Here, we present a public numerical software for the modeling of gamma-ray observables. This code computes the effects on gamma-ray spectra from the development of electromagnetic cascades and cosmological redshifting. The code introduced here is based on the original γ-Cascade, and builds on it by improving its performance at high redshifts, introducing new propagation modules, and adding many more extragalactic radiation field models, which enables the ability to estimate the uncertainties inherent to EBL modeling. We compare the results of this new code to existing Monte Carlo electromagnetic transport models, finding good agreement within EBL uncertainties.

The Effect of Pulse Phases on the Development of Electromagnetic Cascades in the Field Configuration Proposed for the XCELS Facility

The Effect of Pulse Phases on the Development of Electromagnetic Cascades in the Field Configuration Proposed for the XCELS Facility

Kinetic modelling of quantum effects in laser–beam interaction

We present the results of kinetic modelling of quantum effects in laser-beam interaction. In the developed numerical model, electron-positron pair production by hard photons, hard photon emission and the electromagnetic fields generated by the created charged particles are taken into account. Interaction of a relativistic electron beam with a strong laser pulse is analyzed. It is shown that the quantum effects can be important even for moderately intense laser pulses when the number of emitted photons by single electron is not large. Electron-positron pair plasma production in extremely-intense laser field via development of electromagnetic cascades is also studied. The simulation results confirm the prediction of strong laser field absorption in the self-generated electron-positron plasma. It is shown that the self-generated electron-positron plasma can be an efficient source of energetic gamma-quanta.

Measuring parameters of active galactic nuclei central engines with very high energy γ-ray flares

We discuss a ‘compact source’ model of very high energy emission from blazars in which the variability time is determined by the blazar central engine. In this model, electron or proton acceleration close to the supermassive black hole is followed by the development of electromagnetic cascade in a radiatively inefficient accretion flow. Assuming such a model for the TeV blazar PKS 2155−304, we show that the variability properties of the TeV γ-ray signal observed during a bright flare from this source, such as the minimal variability time-scale and the recurrence period of the subflares, constrain the mass and the angular momentum of the supermassive black hole.

Detailed investigations of shower formation in Ge- and W-crystals traversed by 40–287 GeV/c electrons

The development of electromagnetic cascades along crystalline directions have for the first time been measured. As compared to random incidence the number of produced particles is enhanced more than 10 times along axial directions in Ge and increasing with particle energy. The critical angle for this strongly enhanced shower formation is around 1 mrad which means that the effect could be harnessed for high-resolution gamma-ray telescopes.

The theory of the longitudinal development of electromagnetic cascades

A method for the numerical integration of the cascade equations of the longitudinal development of electromagnetic cascades is described. Numerical results on the longitudinal development of electron induced cascades in lead are presented in graphical form. Comparisons with data from Monte Carlo simulations and with experimental data are presented. The accuracy of approximations A and B of conventional cascade theory is investigated.

The development of cascades initiated by nuclear interaction

Abstract The distribution function describing the development of electromagnetic cascades has been derived under the assumption that the primary particlos are y-rays with a certain energy spectrum and angular spread. By comparing experimental results on the lateral distribution of electrons in cascades iniitiated by nuclcar interactions with the calculations presented here one may obtain information on some characteristic features of ‘jets’. At large distances from the cascade ‘core’, the elcctron distribution is identical with that derived from ordinary cascade theory, thus indicating that the angular spread of the primary y-rays can then be neglected. This result is of interest when measurements in large air showers are compared with theory.