Spin and polarization effects on the nonlinear Breit-Wheeler pair production in laser-plasma interaction

Song, Huai Hang and Wang, Wei Min and Li, Yan Fei and Li, Bing Jun and Li, Yu Tong and Sheng, Zheng Ming and Chen, Li Ming and Zhang, Jie (2021) Spin and polarization effects on the nonlinear Breit-Wheeler pair production in laser-plasma interaction. New Journal of Physics, 23 (7). 075005. ISSN 1367-2630 (https://doi.org/10.1088/1367-2630/ac0dec)

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Abstract

The spin effect of electrons/positrons (e -/e +) and polarization effect of γ photons are investigated in the interaction of two counter-propagating linearly polarized laser pulses of peak intensity 8.9 1023 W cm-2 with a thin foil target. The processes of nonlinear Compton scattering and nonlinear Breit-Wheeler pair production based on the spin- and polarization-resolved probabilities are implemented into the particle-in-cell (PIC) algorithm by Monte Carlo methods. It is found from PIC simulations that the average degree of linear polarization of emitted γ photons can exceed 50%. This polarization effect leads to a reduced positron yield by about 10%. At some medium positron energies, the reduction can reach 20%. Furthermore, we also observe that the local spin polarization of e -/e + leads to a slight decrease of the positron yield about 2% and some anomalous phenomena about the positron spectrum and photon polarization at the high-energy range, due to spin-dependent photon emissions. Our results indicate that spin and polarization effects should be considered in calculating the pair production and laser-plasma interaction with the laser power of 10 PW to 100 PW classes.