Cosmic-Ray Muon Intensity Deep Underground versus Depth

Cosmic-ray muons produced in the earth's atmosphere were measured at a depth of 8.71×{}10⁵ g cm^-2 with a large-area (170 m²) liquid-scintillation-detector hodoscope. These data taken together with those of other workers lead to an improved muon vertical-depth intensity curve, Iᵥ(h)=a_μe^-hλ, where Iᵥ(h)=verticalintensity, a_μ=(1.04_-0.13+0.21)×10^-6 cm^-2 sec^-1 sr^-1, λ=(8.04_-0.39+0.35)×10⁴ g cm^-2, and h=depth in g cm^-2. A comparison of these results with those expected from the sea-level muon spectra via an improved calculation may indicate the need for an increased energy loss, probably via the photonuclear interaction as suggested by Keuffel et al. The results are not inconsistent with the presence of the X process of Keuffel et al.