Bright Gamma-Ray Flash in the Lambda-Cube Regime

The availability of multi-petawatt lasers offers in principle new possibilities on investigating various effects [Nakamura 2012, Ridgers 2012, Lezhnin 2018], including γ-photon and e⁺-e^- pair generation. Approximately two decades ago the λ³ regime was envisioned [Mourou 2002], where a single-cycle laser pulse is focused to the diffraction limit level. In [Hadjisolomou 2021, Hadjisolomou 2022] we develop a computational method where a near-single-cycle laser pulse is focused to a spherical-like volume of sub-wavelength diameter, and then bonded into particle-in-cell (PIC) simulations. In the simulations the laser interacted with a mass-limited foil, where a multi-parametric scan of the interaction includes the foil thickness and electron density. Other variables are the laser power and polarisation, revealing that for γ-photon generation in the λ³ regime, the radial laser polarisation is optimal. As a final step, the results from our PIC simulations are used in Monte-Carlo simulations [Kolenaty2022], where the interaction of laser-generated particles with high-Z targets used as a secondary target is revealed. The Monte-Carlo simulations show further e⁺-e^- pair generation, along with generation of unstable nuclei originating from photonuclear interactions.