Abstract
Recent measurements of the intensity of muons below 3000 m.w.e. (metres water equivalent) underground have been combined to give an estimate of the depth-intensity relation and the angular distribution for atmospheric muons down to a maximum depth of approximately 9000 m.w.e.
It is found that the vertical intensity can be represented by the expression
I(0, h) = 9.8 × 10-7 exp(-h/λ)cm-2sec-1sterad-1
where h is the depth in m.w.e. and λ = 810 ± 50 m.w.e.
The corresponding angular distribution at vertical depth h is given by
I(θ, h) = I(0, h) secθ exp{-(h/λ)(secθ - 1)}
where θ is the zenith angle. The implication of the above angular distribution for the estimate of neutrino fluxes in deep underground cosmic-ray experiments is discussed.