Abstract
Cosmic-ray muons are a type of natural radiation with high energy and a strong penetration ability. The flux distribution of such particles at sea level is a key problem in many areas, especially in the field of muon imaging and low background experiments. This paper summarizes the existing models to describe sea-level muon flux distributions. According to different means used, four parametric analytical models and one Monte Carlo model, which is referred to as CRY, are selected as typical sea-level muon flux distribution models. Then, the theoretical values of sea-level muon fluxes given by these models are compared with the experimental sea-level muon differential flux data with kinetic energy values in the range of 1–1,000 GeV in the directions of zenith angles 0° and 75°. The goodness of fit of these models to the experimental data was quantitatively calculated by Pearson’s chi-square test. The results of the comparison show that the commonly used Gaisser model overestimates the muon flux in the low-energy region, while the muon flux given by the Monte Carlo model CRY at the large zenith angle of 75° is significantly lower than that of the experimental data. The muon flux distribution given by the other three parametric analytical models is consistent with the experimental data. The results indicate that the original Gaisser model is invalid in the low energy range, and CRY apparently deviates at large zenith angles. These two models can be substituted with the muon flux models given by Gaisser/Tang, Bugaev/Reyna, and Smith and Duller/Chatzidakis according to actual experimental conditions.
Highlights
Cosmic-ray muons are an essential component of natural radiation at sea level and are produced by the interactions of primary cosmic rays at the top of the Earth’s atmosphere
There are two approaches to obtain the distribution of sealevel muon flux: 1) one way is to derive a parametric analytical model by fitting an empirical model to the measured data of sea-level muon flux; 2) the other way is to use Monte Carlo methods to simulate the process of primary cosmic ray incident into the Earth’s atmosphere and subsequent atmospheric cascade shower and obtain the distribution of muon flux at sea level
Both parametric analytical models and Monte Carlo models are based on the physical process of pion and kaon decay and the attenuation of muons in the process of penetrating the atmosphere
Summary
Cosmic-ray muons are an essential component of natural radiation at sea level and are produced by the interactions of primary cosmic rays at the top of the Earth’s atmosphere. There are two approaches to obtain the distribution of sealevel muon flux: 1) one way is to derive a parametric analytical model by fitting an empirical model to the measured data of sea-level muon flux; 2) the other way is to use Monte Carlo methods to simulate the process of primary cosmic ray incident into the Earth’s atmosphere and subsequent atmospheric cascade shower and obtain the distribution of muon flux at sea level. Tang et al found that the original Gaisser model ignored the curvature of the atmosphere, which caused deviations at large zenith angles, and overestimated muon flux within the energy range of E0 < 100/cosθ. They proposed a segmented modification formula based on Eq 2, which can be written as follows (Tang et al, 2006): ΦT(E0, θ).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
