Reaching ultra-high vacuum for a large vacuum vessel in an underground environmentD. O. Sabulsky, X. Zou, J. Junca, A. Bertoldi, M. Prevedelli, Q Beaufils, R Geiger, A. Landragin, D. Boyer, S. Gaffet, P Bouyer and B. CanuelE3S Web Conf., 357 (2022) 05001DOI: https://doi.org/10.1051/e3sconf/202235705001