# Understanding Gaisser's atmospheric muon parameterization?

1. Jun 7, 2015

### Anchovy

Hi all,

I'm wondering about an equation for the differential flux of atmospheric muons that looks like this:

$$\frac{dN_{\mu}}{dE_{\mu}} \approx \frac{0.14 E^{-2.7}}{cm^{2}.s.sr.GeV} \Bigg\{ \frac{1}{1 + \frac{1.1 E_{\mu}cos(\theta)}{115 GeV}} + \frac{0.054}{1 + \frac{1.1 E_{\mu}cos(\theta)}{850 GeV}} \Bigg\}$$

Despite trawling the net, the only source I can find for it is one textbook (Cosmic Rays and Particle Physics, Thomas K. Gaisser (1990)). However, I'm finding this textbook pretty impenetrable. I want to understand how this equation was arrived at. I'm guessing based on this book it's a difficult thing to explain here but if anyone knows of any document that can get me to at least semi-understand this I would be most grateful.

2. Jun 7, 2015

### PietKuip

It is a fit to the data. Main part is an E^-2.7 energy dependence. The rest is angle dependence.