Short pulse laser produced energetic electron and positron measurements

Very energetic (> MeV) electrons are commonly produced from ultraintense (> 10(19) W/cm(2)) laser-solid interactions. Diagnosing these so-called hot electrons is of fundamental importance in understanding the detailed laser plasma physics present in these interactions, as well as in potential applications. Interestingly, positrons can also be produced in these interactions if the number and effective temperature of hot electrons exceed a threshold value. This additional information may help to better determine the effective electron temperature that exists in these targets. We have designed and constructed a compact spectrometer that can simultaneously measure the energy spectra of both electrons and positrons. Presented here are the principles of the spectrometer together with its experimental results obtained on the ultraintense (> 10(19) W/cm(2)) lasers at Lawrence Livermore National Laboratory and the Rutherford Appleton Laboratory Vulcan petawatt laser. (c) 2006 American Institute of Physics.