  The SHiP-charm project was proposed to measure the associated charm
production induced by 400 GeV/c protons in a thick target, including the
contribution from cascade production. An optimisation run was performed in July
2018 at CERN SPS using a hybrid setup. The high resolution of nuclear emulsions
acting as vertex detector was complemented by electronic detectors for
kinematic measurements and muon identification. Here we present first results
on the analysis of nuclear emulsions exposed in the 2018 run, which prove the
capability of reconstructing proton interaction vertices in a harsh
environment, where the signal is largely dominated by secondary particles
produced in hadronic and electromagnetic showers within the lead target.
