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Optimization and control of bright, ultrafast laser driven X-ray sources

In this paper we describe recent studies on X-ray emission from ultra-fast laser interactions with solids. We describe the dedicated equipment including a powerful femtosecond, Titanium-Sapphire laser system and custom developed diagnostics for the characterization of both the laser performance and the X-ray emission. We show the experimental results obtained from irradiation of Aluminium and Titanium targets including X-ray yield and spectra obtained using single-photon counting and spectroscopy. We discuss correlation of X-ray emission with the measured properties of hot electrons emerging from the target rear side. In particular, forward accelerated fast electrons propagating through a Ti foil are found to be emitted in a cone perpendicular to the target. A comparison of the experimental findings with the results of a PIC simulation is also reported, aimed at identifying the physical processes responsible for the production of this forward propagating population of fast electrons. Finally, we show results of simple optical spectroscopy measurements of scattered light and we discuss the use of these results in view of optimization and control of this kind of X-ray sources.