A size and age dependence study of shower front curvature with GRAPES-3 array.
2019 July 22
Extensive air showers spread laterally mainly when electrons undergo multiple coulumb scattering in the atmosphere.The low energy secondaries and tertiaries will scatter further and will end up farther from the shower core. The particles which are scattered at larger angles during the shower development have higher path lengths and they arrive at the observational level slightly later. Moreover, the particles farther from the core, being lower in energy travel slower giving rise to additional time delays. The time delays, so produced, give rise to a shower front which is non planar in shape. The shape of the shower front has been determined to be conical by various air shower experiments. Here, we present the study of shower front curvature with the data from GRAPES-3 array. We observed that the shower front can be well approximated with a conical shape. However, our detail study has shown that the slope of the conical front has a strong dependence on both shower size and age. The correction of these dependence has led to an improvement in the angular resolution by a factor of two. This would provide efficient observation of multi-TeV gamma ray sources with GRAPES-3