Speaker
Description
In the ongoing search for light dark matter, the DarkMESA and NuDoubt$^{++}$ experiments have combined their efforts to probe a new region of parameter space. DarkMESA is a forthcoming electron beam dump experiment to be located in the new MESA accelerator facility in Mainz, designed to detect light dark matter particles mediated by a hypothetical dark photon $\gamma’$ with the use of a Pb$_2$F crystal calorimeter. The NuDoubt$^{++}$ experiment will utilize an opaque liquid scintillator detector to investigate neutrinoless double beta decay (0$\nu\beta\beta$), a yet-to-be-confirmed beyond Standard Model (BSM) decay process. Due to the expected rarity of these interactions, exceptional background rejection is crucial for identifying potential events. Therefore, both experiments plan to use passive and active shielding layers against cosmic radiation and, for DarkMESA, additional beam-related backgrounds.
This contribution will focus on the development of a liquid scintillator veto prototype for use in both experiments. The prototype will feature a hexagonal geometry with an active volume of approximately $0.351 \,\text{m}^3$, filled with a linear alkylbenzene (LAB) scintillator, doped with $0.2\text{wt.}\%$ Gadolinium to enhance neutron detection. The inner walls will be overlaid with a highly reflective coating to improve photon collection efficiency. The scintillator will be read out by seven 5-inch PMTs mounted on the top surface of the volume. A comparative analysis will be presented, comparing simulation results with initial tests of the prototype to evaluate veto efficiency, with particular emphasis on neutron rejection, given their significance as a background in dark matter searches.
