Test of the photon detection system for the LHCb RICH Upgrade in a charged particle beam by Baszczyk, MK, Benettoni, M, Calabrese, R, Cardinale, R, Carniti, P, Cassina, L, Cavallero, G, Cojocariu, L, Ramusino, AC, D'Ambrosio, C, Dorosz, PA, Easo, S, Eisenhardt, S, Fiorini, M, Frei, C, Gambetta, S, Gibson, V, Gotti, C, Harnew, N, He, J, Keizer, F, Kucewicz, W, Maciuc, F, Maino, M, Malaguti, R, Matteuzzi, C, McCann, M, Morris, A, Muheim, F, Papanestis, A, Pessina, G, Petrolini, A, Piedigrossi, D, Pistone, A, Placinta, VM, Sigurdsson, S, Simi, G, Smith, J, Spradlin, P, Tomassetti, L, Wotton, SA