Enhancing Positron Production using Front Surface Target Structures*

Previous studies have shown that large scale front-surface target structures can significantly increase the energy and narrow the angular distribution of hot electrons generated by laser-solid interactions compared to that for a regular flat target [1, 2]. As a consequence, Bremsstrahlung production can be greatly enhanced using a high-Z converter target [3]. The Bremsstrahlung X-rays can further interact with atomic nuclei in the converter target and create electron-positron pairs through the Bethe-Heitler process [4]. We have studied the electron and positron spectra produced by various target structures by performing 2D PIC simulations and optimized the structure shape for positron production. The simulation results are consistent with our experimental data on OMEGA EP.

1. S. Jiang, A. G. Krygier, et al., Phys. Rev. E 89, 013106 (2014)

2. S. Jiang, L. L. Ji, et al., Phys. Rev. Lett. 116, 085002 (2016)

3. S. Jiang, A. G. Krygier, et al., Eur. Phys. J. D 68, 283 (2014)

4. H. Bethe, W. Heitler, Proc. Royal Soc. of London A, 146, 83 (1934)