Hot Electron Production Using the Texas Petawatt Laser Irradiating Thick Gold Targets* Devin Taylor, Edison Liang, Taylor Clarke, Alexander Henderson, Petr Chaguine, Xin Wang Rice University and Gilliss Dyer, Kristina Serratto, Nathan Riley, Michael Donovan, Todd Ditmire, University of Texas at Austin Abstract We present data for relativistic hot electron production by the Texas Petawatt Laser irradiating solid Au targets with thickness between 1 and 4 mm. The experiment was performed at the short focus target chamber TC1 in July 2011, with intensities on the order of several x10 19 W.cm -2 and laser energies around 50 J. We discuss the design of an electron-positron magnetic spectrometer to record the lepton energy spectra ejected from the Au targets and present a deconvolution algorithm to extract the lepton energy spectra. We measured hot electron spectra out to ~ 50 MeV, which show a narrow peak around 10 – 20 MeV, plus high energy exponential tail. The hot electron spectral shapes appear significantly different from those reported for other PW lasers. We did not observe direct evidence of positron production above the background. * Contribution to HEDLA 2012 Conference Proceedings