Dense High e$+$/e- Ratio Pair Creation using the Texas Petawatt Laser

We report results of pair creation experiments using $\sim$ 100 Joule pulses of the Texas Petawatt Laser to irradiate solid gold and platinum targets, with intensities up to 1.9x10$^{21}$W.cm$^{-2}$ and pulse durations as short as 130 fs. Positron to electron (e$+$/e-) ratios exceeding 15{\%} were observed for many thick disks ( $\ge $4mm) and long narrow rod targets, with the highest observed e$+$/e- ratio approaching 50{\%} for a Pt rod. The inferred pair yield was few x10 $^{10}$ with emerging pair density reaching 10$^{15}$/cc so that the pair skin depth becomes \textless pair jet transverse size, the minimum criterion for the pairs to become a ``plasma.'' These results represent important milestones towards the goal of creating a significant quantity of dense pair-dominated plasma with e$+$/e- approaching 100{\%} and pair skin depth \textless \textless pair plasma size, which will have wide-ranging applications to astrophysics, fundamental physics and innovative technologies. We will discuss some of these potential applications.