  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 $D_s \rightarrow \tau\nu_\tau$ and
$\tau\rightarrow\nu_\tau X$. Directly measuring $D_s\rightarrow \tau$ 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.
