Towards the optimal beam dump experiment to search for feebly interacting particles Kyrylo Bondarenko, Alexey Boyarsky, Richard Jacobsson, Oleksii Mikulenko and Maksym Ovchynnikov Eur. Phys. J. C, 83 12 (2023) 1126 Published online: 13 December 2023 DOI: 10.1140/epjc/s10052-023-12249-5