Generation of GeV positron and γ-photon beams with controllable angular momentum by intense lasers

Xing-Long Zhu,Su-Ming Weng,Tong-Pu Yu,Min Chen,Zheng-Ming Sheng

doi:10.1088/1367-2630/aad71a

Abstract

Although several laser–plasma-based methods have been proposed for generating energetic electrons, positrons and γ-photons, manipulation of their microstructures is still challenging, and their angular momentum control has not yet been achieved. Here, we present and numerically demonstrate an all-optical scheme to generate bright GeV γ-photon and positron beams with controllable angular momentum by use of two counter-propagating circularly-polarized lasers in a near-critical-density plasma. The plasma acts as a ‘switching medium’, where the trapped electrons first obtain angular momentum from the drive laser pulse and then transfer it to the γ-photons via nonlinear Compton scattering. Further through the multiphoton Breit–Wheeler process, dense energetic positron beams are efficiently generated, whose angular momentum can be well controlled by laser–plasma interactions. This opens up a promising and feasible way to produce ultra-bright GeV γ-photons and positron beams with desirable angular momentum for a wide range of scientific research and applications.

Highlights

Positrons—as the antiparticles of electrons—are relevant to a wide variety of fundamental and practical applications [1,2,3,4], ranging from studies of atomic structures of atoms, astrophysics and particle physics to radiography in material science and medical application
The upcoming multi-PW lasers [12, 13] will allow one to access the light intensity exceeding 1023 W cm-2, which pushes light– matter interactions to the exotic QED regime [2, 13,14,15], including high-energy γ-photon emission and dense positron production. Both theoretical [16,17,18] and numerical [19,20,21,22,23,24] studies have shown that the multiphoton Breit–Wheeler (BW) process [25], which was first experimentally demonstrated at SLAC [26], is an effective route to generate high-energy dense positron beams
By use of ultra-intense CP lasers interacting with a near-critical-density (NCD) plasma, we show that ultra-bright GeV γ-photon and dense positron beams with controllable angular momentum can be efficiently produced via nonlinear Compton scattering (NCS) [36, 37] and the multiphoton BW process

Summary

August 2018

Xing-Long Zhu1,2 , Tong-Pu Yu3 , Min Chen1,2 , Su-Ming Weng and Zheng-Ming Sheng. We present and numerically demonstrate an alloptical scheme to generate bright GeV γ-photon and positron beams with controllable angular momentum by use of two counter-propagating circularly-polarized lasers in a near-critical-density plasma. Further through the multiphoton Breit–Wheeler process, dense energetic positron beams are efficiently generated, whose angular momentum can be well controlled by laser–plasma interactions. This opens up a promising and feasible way to produce ultra-bright GeV γ-photons and positron beams with desirable angular momentum for a wide range of scientific research and applications

Introduction

Results and discussion

Conclusion