ИСТИНА

Recently, generation of up to petawatt short (5 to 50 fs) laser pulses, with intensities as high as 1018 W/cm2 and more, became possible on a small-scale, tabletop systems. Such pulses cause acceleration of electrons upon interaction with plasma. This offers a possibility of creating tabletop laser accelerators which would have various advantages over conventional ones such as lower construction cost, lower maintenance cost, and compactness. One of the techniques for the evaluation of the resulting accelerated electron pulse involves directing aforementioned electrons on the face of a dense target and measuring the resulting bremsstrahlung spectrum. This method has an inherent ambiguity in the matter of spectrum transformation, as multiple processes take place simultaneously in the experimental setup. This can be mitigated, to an extent, by using numerical modelling by predicting the resulting gamma spectrum measurement with known electron spectrum and using this data in reverse, thus calculating the initial spectrum from the experimentally observed one. Another problem that arises is the non-negligible probability of simultaneous registration of two gammas – the pile-up effect, which makes it difficult to process spectra with two (or more) parameters – such as, for example, the two-exponential spectrum, which is of great importance in the context of laser-plasma acceleration. Both these problems are considered. An analytical analysis is performed, resulting in recommendations and techniques to be used in practice.