Photonuclear Interactions of High-Energy Muons

Abstract

A calculation of the photonuclear energy-loss coefficient ${b}_{n}$ is made by extrapolating recent SLAC inelastic muon scattering data to the ${10}^{12}$-eV energy region. Previous methods of calculation are discussed, and attention is drawn to the ${q}^{2}$ dependence of the inelastic cross section. It is also noted that ${b}_{n}$ should be $A$ dependent. This is predicted from vector dominance and indicated by the SLAC data on photoproduction off complex nuclei. The value of ${b}_{n}$ obtained is 0.21\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}6}$ ${\mathrm{g}}^{\ensuremath{-}1}$ ${\mathrm{cm}}^{2}$. The relationship of ${b}_{n}$ to observed cosmic-ray muon intensities is discussed, along with the implications of higher ${b}_{n}$ values than are predicted here.