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Abstract

The precise measurement of the intensity of strong laser pulses (intensity I₀ 10²⁰W=cm²) is experimentally very challenging. The equipment involved in intensity measurements for lower-intensity lasers cannot withstand such strong fields, and the tight focus of these pulses make the measurement even more difficult. In this Master thesis I propose a novel method for measuring the intensity of strong laser pulses, in the intensity range between 10²⁰W=cm² and 10²³W=cm². The method exploits the well-known fact that when ultra-relativistic electrons are accelerated they emit radiation primarily in a narrow-cone around the direction of their instantaneous velocity. By allowing ultra-relativistic electrons to propagate through a strong laser pulse, and by measuring the angular aperture of the radiation emitted, it is shown that the value of the peak laser intensity can be accurately inferred. Theoretical accuracies of the order of 10% are in principle foreseen.