STAGE Optimization of pair production using vortex beams

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Description de la mission

It has been known since the pioneering work by Poynting that electromagnetic waves carry
not only energy but also momentum, the latter comprising both linear and angular
components. Recently, the seminal work by Allen highlighted that vortex beams, and
Laguerre-Gauss (LG) beams in particular, carry orbital angular momentum (OAM). Since
then, intense interest has arisen in using LG laser beams carrying OAM from the low
intensity regime to that of ultra-high intensity. In the latter regime, applications to generation
of energetic photon sources and particle acceleration (of positrons in particular) or strong
magnetic field generation have been considered. If, up to now, these studies rely primarily on
numerical simulations, generation of OAM light beams -at the multi-petawatt level- has been
recently demonstrated at the new laser facility CoReLS (Gwangju, South Korea). This opens
the way to the study of OAM laser-matter interaction under extreme light conditions, and of
strong-field quantum electrodynamics processes in particular, as will also be investigated on
the Apollon laser facility currently under construction on the Plateau de Saclay.
The proposed internship aims at investigating electron-positron pair production driven
by OAM vortex beams, as well as generation of sources of high-energy photons (gamma
rays). The mechanism behind pair production is the so-called Breit-Wheeler process in which
a gamma-photon (emitted by a radiating ultra-relativistic electron) collides with the strong
laser field and produces a pair. Identifying the optimal regimes of interaction for abundant
pair production using Gaussian and LG beam will be of outmost importance to prepare the
future experiment at Apollon but also for our understanding of how angular momentum can
be exchanged in between the incident laser pulse and the emitted gamma-photons and
electron-positron pairs. The result of this study can have a variety of application in the
laboratory but also for the understanding of basic phenomena in space : how there can be
angular momentum transfer in astrophysical objects or how fast particles in the cosmic ray
spectra can be accelerated by the interaction of pair plasma jets.
The study will be conducted by the trainee in the theory and simulation group of LULI.
The core of the internship will be performing extensive 3D Particle-In-Cell (PIC) simulation
using the new, open-source and collaborative PIC code SMILEI.

Profil recherché

Théorie, calcul et simulations par code PIC, connaissance de physique du plasma et de programmation en C et python.

Niveau de qualification requis

Bac + 4/5 et +
  • Employeur
  • Secteur d’activité de la structure
    Enseignement - Formation - Recherche
  • Effectif de la structure
    De 21 à 50 salariés
  • Site internet de la structure
  • Type de stage ou contrat
    Stage pour lycéens et étudiants en formation initiale
  • Date prévisionnelle de démarrage
  • Durée du stage ou contrat
    Plus de 2 mois et jusqu'à 4 mois
  • Le stage est-il rémunéré ?
  • Niveau de qualification requis

    Bac + 4/5 et +
  • Lieu du stage
    Sorbonne Universite Campus Pierre et Marie Curie
    4 place Jussieu
  • Accès et transports
    transports publics