Commissioning of the vacuum system of the KATRIN Main Spectrometer

M. Arenz, M. Babutzka, M. Bahr, J.P. Barrett, S. Bauer, M. Beck, A. Beglarian, J. Behrens, T. Bergmann, U. Besserer, J. Blümer, L.I. Bodine, K. Bokeloh, J. Bonn, B. Bornschein, L. Bornschein, S. Büsch, T.H. Burritt, S. Chilingaryan, T.J. Corona, L. De Viveiros, P.J. Doe, O. Dragoun, G. Drexlin, S. Dyba, S. Ebenhöch, K. Eitel, E. Ellinger, S. Enomoto, M. Erhard, D. Eversheim, M. Fedkevych, A. Felden, S. Fischer, J.A. Formaggio, F. Fränkle, D. Furse, M. Ghilea, W. Gil, F. Glück, A. Gonzalez Ureña, S. Görhardt, S. Groh, S. Grohmann, R. Grössle, R. Gumbsheimer, M. Hackenjos, V. Hannen, F. Harms, N. Haußmann, F. Heizmann, K. Helbing, W. Herz, S. Hickford, D. Hilk, B. Hillen, T. Höhn, B. Holzapfel, M. Hötzel, M.A. Howe, A. Huber, A. Jansen, N. Kernert, L. Kippenbrock, M. Kleesiek, M. Klein, A. Kopmann, A. Kosmider, A. Kovalík, B. Krasch, M. Kraus, H. Krause,i M. Krause, L. Kuckert, B. Kuffner, L. La Cascio, O. Lebeda, B. Leiber, J. Letnev, V.M. Lobashev, A. Lokhov, E. Malcherek, M. Mark, E.L. Martin, S. Mertens, S. Mirz, B. Monreal, K. Müller, M. Neuberger, H. Neumann, S. Niemes, M. Noe, N.S. Oblath, A. Off, H.-W. Ortjohann, A. Osipowicz, E. Otten, D.S. Parno, P. Plischke, A.W.P. Poon, M. Prall, F. Priester, P.C.-O. Ranitzsch, J. Reich, O. Rest, R.G.H. Robertson, M. Röllig, S. Rosendahl, S. Rupp, M. Ryšavý, K. Schlösser, M. Schlösser, K. Schönung, M. Schrank, J. Schwarz, W. Seiler, H. Seitz-Moskaliuk, J. Sentkerestiová, A. Skasyrskaya, M. Slezák, A. Špalek, M. Steidl, N. Steinbrink, M. Sturm, M. Suesser, H.H. Telle, T. Thümmler, N. Titov, I. Tkachev, N. Trost, A. Unru, K. Valerius, D. Vénos, R. Vianden, S. Vöcking, B.L. Wall, N. Wandkowsky, M. Weber, C. Weinheimer, C. Weiss, S. Welte, J. Wendel, K.L. Wierman, J.F. Wilkerson, D. Winzen, J. Wolf, S. Wüstling, M. Zacher, S. Zadoroghny and M. Zboril

Abstract

The KATRIN experiment will probe the neutrino mass by measuring the ß-electronenergy spectrum near the endpoint of tritium ß-decay. An integral energy analysis will be performedby an electro-static spectrometer (“Main Spectrometer”), an ultra-high vacuum vessel with a lengthof 23.2 m, a volume of 1240m3, and a complex inner electrode system with about 120 000 individualparts. The strong magnetic field that guides the -electrons is provided by super-conductingsolenoids at both ends of the spectrometer. Its influence on turbo-molecular pumps and vacuumgauges had to be considered. A system consisting of 6 turbo-molecular pumps and 3 km ofnon-evaporable getter strips has been deployed and was tested during the commissioning of thespectrometer. In this paper the configuration, the commissioning with bake-out at 300°C, and the performance of this system are presented in detail. The vacuum system has to maintain a pressure inthe 10-11 mbar range. It is demonstrated that the performance of the system is already close to thesestringent functional requirements for the KATRIN experiment, which will start at the end of 2016.