Zenith and azimuth angle dependence of extensive air shower thickness

Document Type : Research Paper


1 Physics Department, Faculty of Science, Imam Khomeini International University, Qazvin, Iran

2 Department of Physics, Faculty of Education, Faryab University, Faryab, Afghanistan


The arrival time distribution of simulated extensive air shower particles, for $10^{14}-10^{16}$ eV showers initiated by protons, for the observation level of the ALBORZ-I array in Tehran, has been investigated. We report the results of our analysis on the arrival time spread of simulated shower particles in several regions in the shower front, which are suitably chosen to demonstrate the variation of shower thickness with the core distance, and azimuth angle, for slanted showers of different zenith angles. Using the standard deviation of the time distribution as an indicator of the shower thickness, and defining appropriate observation zones on the ground, we found an asymmetry in the shower thickness of slanted showers. It seems that the early parts in the shower front are thicker than the late parts. A misinterpretation of the thickness of slanted shower fronts in an other research has been corrected. Implications for improvement of accuracy in the shower axis direction estimation has been discussed.


[1] Aielli, G., et al. 2012, Nucl. Instrum. Methods Phys. Res., Sect. A, 661, S50.
[2] Bahmanabadi, M., & Mortazavi Moghadam, S. 2018, New Astron. , 61, 5.
[3] Heck, D., et al. 1998. CORSIKA: A Monte Carlo Code to Simulate Extensive Air Showers. Report FZKA 6019. Forschungszentrum, Karlsruhe; available from http://wwwik.fzk.de/corsika/physics description/corsika phys.html.
[4] Kalmykov, N. N., et al. 1997, Nucl. Phys. B (Proc. Suppl.), 52, 17.
[5] Fesefeldt, H. 1985, The Simulation Of Hadronic Showers-Physics and Applications. Report No. PITHA-85/02. RWTH, Aachen.
[6] Abdollahi, S., et al. 2016, Atropart. Phys., 76, 1.
[7] Ataei, S. M. 2019, Investigation of azimuthal asymmetry in the time distribution of extensive air showers by Monte carlo simulation, Master Thesis, Imam Khomeini International University, Qazvin, Iran.
[8] Bahmanabadi, M., et al. 2002, Exp. Astron., 13, 39.
[9] Bahmanabadi, M., & Heydarizadeh, M. 2019, Nucl. Instrum. Methods Phys. Res., Sect. A, 932, 62.