High e+/e- ratio dense pair creation with 1021 W.cm-2 laser irradiating solid targets

Abstract

We report results of new pair creation experiments using ∼100 Joule pulses of the Texas Petawatt Laser to irradiate solid gold and platinum targets, with intensities up to ∼1.9 × 1021 W.cm-2 and pulse durations as short as ∼130 fs. Positron to electron (e+/e-) ratios >15% were observed for many thick disk and rod targets, with the highest e+/e- ratio reaching ∼50% for a Pt rod. The inferred pair yield was ∼ few ×1010 with emerging pair density reaching ∼1015 /cm3 so that the pair skin depth becomes