Are we close to transfering optical power into gamma-rays and pairs?

The next generation of lasers is expected to reach powers on the order of 10 PW, which opens new horizons for exploring quantum effects in laser-matter interactions. On one hand, this offers a new experimental platform to probe matter at fundamental levels, while on the other hand, this technology can be potentially used to design novel gamma-ray and electron-positron beam sources. Relativistic electron beams and lasers with intensities above I>10^20 W/cm^2 allow entering the radiation-dominated and quantum regime of interaction. Electron energy loss due to the classical radiation reaction could be measured by colliding Wakefield accelerated electron beams with state-of-the-art laser pulses [1]. This was demonstrated in two recent experiments [2]. Using quasi-monoenergetic electron beams, one can further expect to measure signatures of quantum radiation reaction in the electron energy spread and divergence [3]. There is also a practical benefit of radiation reaction: a radiation reaction-induced particle trapping at extreme intensities can assist efficient electron acceleration in plasma channels [4]. With the next generation of lasers, laser-electron beam scattering configurations will generate electron-positron pairs in conditions where they can be immediately accelerated to multi-GeV energies [5]. Multiple-laser optical traps can be used to confine the self-generated electron-positron pairs in the region of the highest laser intensity, resulting in an efficient energy conversion into gamma-rays and dense pair plasma [5] containing approximately the same number of electrons and positrons [6]. [1] M. Vranic et al, PRL (2014) [2] J. M. Cole et al, PRX (2018); K. Poder et al, ArXiv (2017) [3] M. Vranic et al, NJP (2016) [4] M. Vranic et al, PPCF (2018) [5] M. Vranic et al, PPCF (2017); T. Grismayer et al, POP(2016); T. Grismayer et al, PRE (2017) [6] M. Vranic et al, S. Rep. (2018).