Background assessment for the TREX dark matter experiment J. Castel, S. Cebrián, I. Coarasa, T. Dafni, J. Galán, F. J. Iguaz, I. G. Irastorza, G. Luzón, H. Mirallas, A. Ortiz de Solórzano and E. Ruiz-Chóliz Eur. Phys. J. C, 79 9 (2019) 782 Published online: 21 September 2019 DOI: 10.1140/epjc/s10052-019-7282-6