The study of open charm meson production provides an efficient tool for detailed investigations of the properties of hot and dense matter formed in nucleus-nucleus collisions. In particular, charm mesons are of vivid interest in the context of the phase-transition between confined hadronic matter and the quark-gluon plasma. However, due to low yield of charm particles systematic measurements of them were not performed yet at the SPS energy regime.
The NA61/SHINE experiment at the CERN/SPS aims to investigate the QCD phase diagram of strongly interacting matter in the region of moderate temperatures and high net-baryon densities.
Recently, the experimental setup of NA61/SHINE experiment was supplemented with a small-acceptance Vertex Detector (SAVD) which was motivated by the importance and the possibility of the first direct measurements of open charm mesons in heavy ion collisions at SPS energies. The SAVD is a silicon pixel detector located close to the target; the high spatial resolution of it allows to significantly improve primary and secondary vertex resolution.
First data takings of Xe+La and Pb+Pb collisions at 150A GeV/c with SAVD were performed in 2017 and 2018, and a D0 meson signal was extracted in the pion+Kaon decay channel. This was the first direct observation of open charm in nucleus-nucleus collisions at the SPS energies.
This motivated the NA61/SHINE to perform a systematic measurements of open charm production in Pb+Pb collisions in the period 2022-2024 after the major detector upgrade conducted during the Long Shutdown 2, which will significantly increase data taking rate and allow detailed study of open charm. The analysis of the upcoming data will be the main task of a mater study project which is expected to lead to a high profile scientific publication.