On the estimation of the depth of maximum of extensive air showers using the steepness parameter of the lateral distribution of Cherenkov radiation

Abstract

Using Monte Carlo simulation of extensive air showers, we showed that the maximum depth of showers, Xmax can be estimated using P=Q(100)∕Q(200), the ratio of Cherenkov photon densities at 100 and 200 meters from the shower core, which is known as the steepness parameter of the lateral distribution of Cherenkov radiation on the ground. A simple quadratic model has been fitted to a set of data from simulated extensive air showers, relating the steepness parameter and the shower maximum depth. Then the model has been tested on another set of simulated showers. The average difference between the actual maximum depth of the simulated showers and the maximum depth obtained from the lateral distribution of Cherenkov light is about 9 g/cm2. In addition, possibility of a more direct estimation of the mass of the initial particle from P has been investigated. An exponential relation between these two quantities has been fitted. Applying the model to another set of showers, we found that the average difference between the estimated and the actual mass of primary particles is less than 0.5 atomic mass unit.