Marcel Strzys Max-Planck-Institut fuer Physik

Differences in electron and gamma ray induced air shower (pdf)

Imaging Air Cherenkov Telescopes have to deal with a large isotropic background from air showers introduced by cosmic rays. As hadronic events constitute by far the largest fraction, in the last decades high efforts were made to suppress them. The techniques are based on differences in the shower development of hadronic and gamma ray events . Electrons induce pure electromagnetic cascades like gamma rays, so they can just be discriminated from the gamma ray signal by their arrival direction, so far. This kind of separation is sufficient for the detection of a large number of point source by IACTs. Nevertheless, in case of largely extended sources electrons are a limiter for the sensitivity of the instrument, as well it will be for the future 4th generation of IACTs. In this talk I will present some slight differences in electron and gamma ray induced air shower which may allowed to further improve the sensitivity of IACTs and enable them to observe new kinds of sources.