Speaker
Description
Very-high-energy (VHE) cosmic gamma-rays are messengers of violent processes in the Universe. At lower energies, this radiation can be detected by satellites experiments. However, as the energy increases the flux becomes too scarce, and one must rely on ground-based observatories to detect gamma-rays, taking advantage of the large electromagnetic showers that are created when it enters the Earth atmosphere.
In order to study transient phenomena, it is necessary to cover large portions of the sky, which can be achieved by placing arrays at high-altitude. However, as these arrays sample only the shower secondary particles that reach the ground, the determination of the primary gamma-ray energy, while proportional to the number of detected particles, is deteriorated by the stochastic fluctuations of the interactions in the shower. In fact, at low energies, the uncertainty on the shower stage is the main responsible for an energy reconstruction resolution of the order of 100%.
The stage at which the shower reaches the ground is connected with the depth at which the cascade reaches its maximum, Xmax. At extreme energy and in cosmic ray showers it has been demonstrated that the analysis of the arrival time structure of the particles at the ground can be used as a reliable estimator of Xmax.
Hence, in this study, we propose to investigate through dedicated simulations the time structure of electromagnetic showers, at the energies relevant for VHE gamma-rays, to create a variable to estimate the value of Xmax, and consequently improve the current energy reconstruction algorithms significantly.
