A thermoluminescence detector-based few-channel spectrometer for simultaneous detection of electrons and photons from relativistic laser-produced plasmas

A new method was applied to simultaneously measure the absolute energy- and angle-dependent emission of electrons (500 keV to 20 MeV) and photons (50 keV to 2 MeV) emitted by laser-produced plasmas. For this purpose, a newly developed few-channel spectrometer based on thermoluminescence detectors was used. The device measures the curve of depth dose values in a stack of different materials. The deconvolution of electron and photon spectra from the depth dose curve was performed using a computing algorithm based on a Bayesian inference using Gibbs sampling. Several characteristics of the measured particle spectra were investigated: The electron distribution function of the electrons was found to be describable by Maxwellian distributions in energy. The hot electron temperatures obtained (between 1.1 and 1.7 MeV depending on target material and thickness) are in accordance with well-known scaling laws. The angular emission of the electrons was found to be highly anisotropic with a maximum in the direction of the laser reflection (region of the target normal and parallel to the target surface) for a thick target and an additional maximum in the forward direction of the laser for a thin target. Conversion efficiencies depending on the material and thickness of the target for the conversion of laser light energy to relativistic electrons and of electrons to photons were determined to be up to 10% and 1%, respectively. (C) 2003 American Institute of Physics.