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

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 < pair jet transverse size. These results represent major milestones towards the goal of creating a significant quantity of dense pair-dominated plasmas with e+/e- approaching 100% and pair skin depth 蠐 pair plasma size, which will have wide-ranging applications to astrophysics and fundamental physics.