Creating dense gamma-rays and electron-positron pairs with 10^21 W.cm^-2 short-pulse laser*

On behalf of the Rice-UTA-MDA Positron-Gamma-Ray Collaboration*, we report the latest results of the 2016-2018 dense gamma-ray and positron experiments.  Using the Texas Petawatt Laser (TPW) to irradiate thick Au and Pt targets at intensities ≥10^21 W/cm^2 , we have created high-density (10^15/cm^3), short-pulse (100 fs) e+e- pair and gamma-ray jets with in-situ physical parameters comparable to those postulated for cosmic gamma-ray bursts.  For large cm-sized targets, we discover that hot electron emission is suppressed in a cone between the target normal and laser forward directions, while the positron emission is not suppressed.  This leads to the creation of angle-selectable positron-dominated jets, with many applications to fundamental physics and astrophysics.  We will also present the gamma-ray data from  a new type of gamma-ray spectrometer, and discuss potential future applications of ultra-intense multi-MeV gamma-ray beams.

* E. Liang, W. Lo, Y. Lu, K. Yao, A. Henderson, E. Marchenka, F. Fasanelli,  A. Zhang, W. Fu, P. Chaguine, Rice University; H. Hassan, A. Dashko, G. Glen, G. Tiwari, H. Quevedo, G. Dyer, M. Donovan, T. Ditmire, UT Austin; G. Wong, Y. Zhang, MD Anderson Cancer Center.