NICHE: Air-Cherenkov observation at the TA site

The Non-Imaging CHErenkov (NICHE) Array has been deployed at the Telescope Array Middle Drum site, and has been collecting data. We see many coincidences with TALE fluorescence mirror events, establishing hybrid imaging/non-imaging air-Cherenkov observation of cosmic ray air showers. We have verified the TALE Profile-Constrained Geometry Fit of Cherenkov events at the 3° level. We have performed hybrid timing fits between NICHE and TALE and have established that the growth in the FWHM of the NICHE signal with the distance of the shower core depends on the height of the shower maximum.

Estimating primary energy of cosmic rays by calculating secondary particles density in optimum distance from shower core

Optimum distance (R[Formula: see text]) is a distance from the shower core in which the density calculated by lateral distribution function, has its minimum uncertainty. In this paper, using CORSIKA code, proton, carbon and iron primary in the energy range between 10[Formula: see text]–[Formula: see text][Formula: see text]eV are simulated to find R[Formula: see text] for Alborz-I array located at an altitude of 1200[Formula: see text]m above sea level. It is shown that R[Formula: see text] is approximately independent of characteristics of primary particle and it is only dependent to array configuration. Dependency of R[Formula: see text] on layout and detector spacing for 20 Alborz-I array detectors, are studied. It is shown that the Alborz-I array layout and its detector spacing result into the best (minimum uncertainty) R[Formula: see text] for its number of detectors. In this work, R[Formula: see text] for Alborz-I array is obtained about [Formula: see text][Formula: see text]m (from NKG function) and [Formula: see text][Formula: see text]m (from NKG type function). In addition, it is shown that, by finding dependency of primary energy to density in optimum distance, energy of primary particle can be estimated well. An energy estimation function is suggested and the function is examined by another set of simulated showers.

Parameterization of Cherenkov Light Lateral Distribution Function as a Function of the Zenith Angle around the Knee Region

Cherenkov light lateral distribution function (CLLDF) simulation was fullfiled using CORSIKA code for configurations of Tunka EAS array for different zenith angles. The parameterization of the CLLDF was carried out as a function of the destance from tehe shower core in extensive air showers (EAS) and zenith angle on the basis of the CORSIKA simulation for primary proton around the knee region with the energy 3.1015 eV at different zenith angles. The parametrized CLLDF is verified in comparison with the simulation that performed using CORSIKA code for two zenith angles.