Tau neutrino fluxes from atmospheric charm

We present an evaluation of the atmospheric tau neutrino flux in the energy range between ${10}^2$ and ${10}^6\hspace{0.5em}\mathrm{GeV}.$ The main source of tau neutrinos is from charmed particle production and decay. The ${\nu }_{\tau }\overrightarrow{N}\tau X$ event rate for a detector with a water equivalent volume of $1\hspace{0.5em}{\mathrm{km}}^3$ is on the order of 60–100 events per year for $E_{\tau }>100\mathrm{}\hspace{0.5em}\mathrm{GeV},$ reducing to 18 events above 1 TeV. Event rates for atmospheric muon neutrino oscillations to tau neutrinos are also evaluated.