Detection of primary photons in high-energy cosmic rays using Cerenkov imaging and surface detectors.

Casaburo F.
  Venerdì 15/09   15:30 - 18:30   Aula A203   III - Astrofisica
Given that two important experiments to study $\gamma$ rays, the Lasrge High Altitude Air Shower Observatory (LHAASO) and the Cerenkov Telescope Array (CTA), are currently in the planning phase, we analyzed some simulations made by the COsmic Ray SImulations for KAscade (CORSIKA) to compare Extensive Air Showers (EAS) induced by protons to EAS induced by $\gamma$. Choosing two primary particles energies $E\sim 150$ GeV and $E\sim 1$ TeV, secondary particles distributions were plotted at observation level; by plots we can see that secondary particles of $\gamma$-ray showers are arranged on surfaces centered in EAS core smaller than those for particles of proton showers. Later it was observed that in proton showers we have more secondaries $\mu^{\pm}$ than in $\gamma$-ray showers. Calculating particles density in circular crowns centered in the EAS core, we showed that, increasing the distance from the core, the density decreasing of secondary particles produced by $\gamma$-ray showers is faster than that for secondary particles produced by proton showers. Lastly, arbitrarily choosing 3 distances from the core, 10 m, 100 m and 600 m, secondaries particles density was calculated, showing that for fixed distances, increasing primary particles energy, secondary particles density increases too. Obtained results are important because they allow us to test teories at the basis of LHAASO and CTA realization, that is thanks to algorithms based on differences between lateral developments of showers in atmosphere, lateral distribution at observation level about charged and neutral particles around the shower core, number of $\mu^{\pm}$, it will be possible to discern $\gamma$-ray showers from proton showers ($\frac{proton EAS}{\gamma EAS} \sim 100$) to acquire events and to reject hadronic background. Finally, comparing experimental data to obtained mean values of studied physical quantities as a function of primary particles energies, it will be possible to estimate the latter.