Sealed operation, and circulation and purification of gas in the HARPO TPC M. Frotin, P. Gros, D. Attié, D. Bernard, V. Dauvois, A. Delbart, D. Durand, Y. Geerebaert, S. Legand, P. Magnier et al. (2 more) EPJ Web Conf., 174 (2018) 05002 Published online: 21 February 2018 DOI: 10.1051/epjconf/201817405002