Upgrading and testing the 3D reconstruction of gamma-ray air showers as observed with an array of Cherenkov telescopes

摘要

Stereoscopic arrays of Imaging Cherenkov Telescopes allow to reconstruct gamma-ray-induced showers in3 dimensions. An analysis method based on a simple 3D-model of electromagnetic showers and implemented in theframework of the H.E.S.S. experiment was recently improved by an additional quality criterion which reduces the backgroundcontamination by a factor of about 2 in the case of extended sources, while hardly affecting gamma-ray selection efficiency.Moreover, the dramatic flares of PKS 2155-304 in July 2006, which provided H.E.S.S. data with an almost pure gamma-ray sample, offered the unique opportunity of a precision test of the 3D-reconstruction method as well as of the H.E.S.S.simulations used in its calibration. An agreement at a few percent level is found between data and simulations for thedistributions of all 3D shower parameters.