Results from the CERN pilot CLOUD experiment by Duplissy, J, Enghoff, M, Aplin, K, Arnold, F, Aufmhoff, H, Avngaard, M, Baltensperger, U, Bondo, T, Bingham, R, Carslaw, K, Curtius, J, David, A, Fastrup, B, Gagne, S, Hahn, F, Harrison, R, Kellett, B, Kirkby, J, Kulmala, M, Laakso, L, Laaksonen, A, Lillestol, E, Lockwood, M, Makela, J, Makhmutov, V, Svensmark, J