Conceptual design report for the LUXE experiment H. Abramowicz, U. Acosta, M. Altarelli, R. Aßmann, Z. Bai, T. Behnke, Y. Benhammou, T. Blackburn, S. Boogert, O. Borysov et al. (81 more) Eur. Phys. J. Spec. Top., 230 11 (2021) 2445-2560 Published online: 08 September 2021 DOI: 10.1140/epjs/s11734-021-00249-z