A first measurement of the interaction cross section of the tau neutrino
The DONuT experiment collected data in 1997 and published first results in 2000 based on four observed $ν_τ$ charged-current (CC) interactions. The final analysis of the data collected in the experiment is presented in this paper, based on $3.6 \times 10^{17}$ protons on target using the 800 GeV Tevatron beam at Fermilab. The number of observed $ν_τ$ CC interactions is 9, from a total of 578 observed neutrino interactions. We calculated the energy-independent part of the tau-neutrino CC cross section ($ν+ \bar ν$), relative to the well-known $ν_e$ and $ν_μ$ cross sections. The ratio $σ(ν_τ)$/$σ(ν_{e,μ})$ was found to be $1.37\pm0.35\pm0.77$. The $ν_τ$ CC cross section was found to be $0.72 \pm 0.24\pm0.36 \times 10^{-38}$ cm$^{2}\rm{GeV}^{-1}$. Both results are in agreement the Standard Model.