Study of tau-neutrino production at the CERN SPS

The DsTau project proposes to study tau-neutrino production in high-energy proton interactions. The outcome of this experiment are prerequisite for measuring the $nu_tau$ charged-current cross section that has never been well measured. Precisely measuring the cross section would enable testing of lepton universality in $nu_tau$ scattering and it also has practical implications for neutrino oscillation experiments and high-energy astrophysical $nu_tau$ observations. $D_s$ mesons, the source of tau neutrinos, following high-energy proton interactions will be studied by a novel approach to detect the double-kink topology of the decays $D_s rightarrow taunu_tau$ and $taurightarrownu_tau X$. Directly measuring $D_srightarrow tau$ decays will provide an inclusive measurement of the $D_s$ production rate and decay branching ratio to $tau$. The momentum reconstruction of $D_s$ will be performed by combining topological variables. This project aims to detect 1,000 $D_s rightarrow tau$ decays in $2.3 times 10^8$ proton interactions in tungsten target to study the differential production cross section of $D_s$ mesons. To achieve this, state-of-the-art emulsion detectors with a nanometric-precision readout will be used. The data generated by this project will enable the $nu_tau$ cross section from DONUT to be re-evaluated, and this should significantly reduce the total systematic uncertainty. Furthermore, these results will provide essential data for future $nu_tau$ experiments such as the $nu_tau$ program in the SHiP project at CERN. In addition, the analysis of $2.3 times 10^8$ proton interactions, combined with the expected high yield of $10^5$ charmed decays as by-products, will enable the extraction of additional physical quantities.