Controlling Interaction of Pair-plasmas with Laser-plasmas: Laser Positron Accelerator*

Laser electron accelerators [1], utilizing CPA laser driven collective plasma modes are now recognized as a means for centimeter-scale acceleration of multi-GeV electron beams with various applications. Unfortunately, even with the rapid development of laser electron accelerators, laser acceleration of exotic particles like positrons remains unexplored. We propose to pioneer the first-ever prototype of a Laser Positron Accelerator that will pave the way for centimeter-scale acceleration of tunable positron beams at numerous laser facilities worldwide with new applications such as crystal channeling [2] and acceleration [3]. This work uses an innovative two-laser two-stage model [4] where a laser-driven plasma (stage 2) is used to post-process $e^+$-$e^−$ pair-plasmas produced (stage 1) in a target by laser accelerated electrons. It is timely due to the success of two recent experiments: (a) all-optical shower production [5]; (b) multistage laser electron acceleration [6]. The goal is to tune the pair-plasma characteristics in order to match them with the chosen post-processing stage properties, specifically to trap and accelerate a spectrally peaked positron beam through controlled interaction [4] between pair-plasma and laser-driven plasma waves.