др Марија Вранић и др Томас Грисмајер

18. априла 2022.

У оквиру дуплог семинара Центра за изучавање комплексних система Института за физику у Београду, у четвртак, 21. априла 2022. године у 14 часова путем Zoom платформе, др Марија Вранић (GoLP/Институт за плазму и нуклеарну фузију, Високи технички институт, Универзитет у Лисабону), одржаће предавање:

Sources of electrons, positrons, and gamma-rays from lasers within plasma channels


The recent rise in laser intensities accompanied by the ongoing construction of new laser facilities such as ELI, the Vulcan 10 PW, and APOLLON will place intensities above 10^23 W/cm^2 within reach. While propagating through a pre-formed plasma channel, a laser of such intensity allows for direct laser acceleration (DLA) of leptons in the radiation reaction dominated regime. The DLA scheme has already been demonstrated to provide high-charge electron beams (at a nC level) with moderate laser intensities  (10^20 W/cm^2). In this talk we will show what can be accomplished with near-future laser facilities. We find that increasing the laser power is bound to augment the charge content even further. The field structure formed due to electron beam loading allows for accelerating positrons. What is more, the interaction in the radiation dominated regime will provide a high flux of emitted photons, in hard x-ray and gamma-ray range. These photons can then be used as a seed for electron-positron pair creation, as well as a radiation source for applications.

Након тога др Томас Грисмајер (GoLP/Институт за плазму и нуклеарну фузију, Високи технички институт, Универзитет у Лисабону), одржаће предавање:

Electron-positron-photon cascades in ultrastrong electromagnetic fields


Electron-positron pair plasmas are tightly related to extreme astrophysical objects such as pulsar magnetospheres or gamma-ray bursts. Due to the inherent difficulties of studying these remote objects, it is desirable to study dense pair plasmas in the laboratory, both for fundamental purposes and astrophysical applications. The magnitude of the laser fields expected in the next generation of laboratories overlaps with the estimated fields of milliseconds pulsars. Producing pair plasmas in ultrastrong fields may demonstrate that we can mimic the conditions appropriate to these astrophysical environments in laboratories. The pair creation in such energy density environments is caused by the decay of gamma rays in intense fields. As pulsars efficiently convert the large-scale Poynting flux to gamma rays, the laboratory analog of a pulsar isexpected to efficiently convert optical laser light into gamma rays. This process usually leads to quantum electrodynamics (QED) cascades, as the pairs created re-emit hard photons that decay anew in pairs, eventually resulting in electron-positron-photon plasmas. In this talk we will present the QED cascades in the laboratory where the electromagnetic trap is comprised of colliding lasers, and in Pulsar magnetospheres.

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Meeting ID: 827 0093 8432
Passcode: 008340