Ben Liesfeld

Study of photo-proton reactions driven by bremsstrahlung radiation of high-intensity laser generated electrons

Photo-nuclear reactions were investigated using a high power table-top laser. The laser system at the University of Jena ( I 3-5◊ 10 19 W cm 2 ) produced hard bremsstrahlung photons (kT 2.9 MeV) via a laser-gas interaction which served to induce (, p) and (, n) reactions in Mg, Ti, Zn and Mo isotopes. Several (, p) decay channels were identified using nuclear activation analysis to determine their integral reaction yields.

Single-shot autocorrelation at relativistic intensity

We demonstrate the single-shot autocorrelation of an ultrashort laser pulse at relativistic intensity (above 1018W∕cm2). The pulse is divided into two equally strong laser pulses which are focused into a He-gas jet under an angle of 180°. Nonlinear Thomson scattering from plasma electrons is used as second-order autocorrelation signal.

Navigating Comfortably across the Retina

Laser photocoagulation has been widely used to treat retinal disorders like diabetic retinopathy and macular degeneration for decades. The delivery systems - the slit-lamp - and especially their imaging capabilities have not evolved significantly in that time. The NAVILAS Laser System was recently developed based on a digital ophthalmoscope providing the retinal surgeon with the necessary tools to navigate across the retina, locate the relevant loci and perform an efficient and effective photocoagulation. It represents the ideal platform to evaluate novel treatment methods which cannot easily be visualized with standard delivery systems.

Thomson backscattering from laser-accelerated electrons

We present the first observation of Thomson backscattered light from laser-accelerated electrons. Time-resolved electron spectra during the acceleration process have been obtained.

Experiments with Counter-propagating Laser Pulses at Relativistic Intensities

We demonstrate the precise spatial and temporal overlap of two counter-propagating, focused laser pulses at intensities above the relativistic threshold. In a first experiment a single-shot autocorrelation was carried out. Further applications are discussed

High-intensity Laser Induced Photo-proton Reactions

We demonstrate for the first time photo-proton nuclear reactions in various nuclei induced by a high-intensity, high repetition rate table-top laser and measure ratios of photo-proton/photo-neutron cross-sections

Electron and Proton Acceleration from Solid Targets by High-intensity Table-top Lasers

Electron and proton beams were investigated using a compact laser with intensities up to 2times1019 W/cm2 irradiating thin targets. For the direction of the electron beam theory and experiment disagree