At the Institute for Nuclear Physics in Mainz the new electron accelerator MESA will go into operation within the next years. In the extracted beam operation (150$\,$MeV, 150$\,\mu$A) the P2 experiment will measure the weak mixing angle in electron-proton scattering. The high-power beam dump of this experiment and the 20,000 hours operation time are ideally suited for a parasitic dark sector experiment $-$ DarkMESA.

The experiment is designed for the detection of Light Dark Matter (LDM) which in the simplest model couples to a massive vector particle, the dark photon $\gamma$'. It can potentially be produced in the P2 beam dump by a process analogous to photon Bremsstrahlung and can then decay in Dark Matter (DM) particle pairs $\chi\overline{\chi}$ if kinematically allowed. A fraction of them scatter off electrons or nuclei in the DarkMESA calorimeter.

For the calorimeter, high-density PbF$_2$ and lead glass SF5 Cherenkov radiators and photomultipliers from previous experiments will be used. In Phase A a prototype with 25 PbF$_2$ crystals and in Phase B $\sim\,$2000 PbF$_2$ and SF5 crystals with a total active volume of 0.7$\,$m$^3$ are foreseen. For the prototype stage, a hermetic veto system with two layers of plastic scintillators and 1$\,$cm of lead shielding is currently under development.

Within a MadGraph and Geant4 simulation the accessible parameter space was evaluated. The experimental setup was optimized and further concepts were investigated.

DarkMESA DRIFT is currently considered as an addition to the project. A Time Projection Chamber (TPC) filled with CS$_2$ at low pressure will serve as DM detector. With the nuclear recoil threshold being in the keV range the accessible parameter space can be extended.