# Gamma-induced background in the KATRIN main spectrometer

Authors
And 106 more
• 1 Technische Universität München, James-Franck-Str. 1, Garching, 85748, Germany , Garching (Germany)
• 2 IRFU, CEA, Université Paris-Saclay, Gif-sur-Yvette, 91191, France , Gif-sur-Yvette (France)
• 3 Rheinische Friedrich-Wilhelms Universität Bonn, Helmholtz-Institut für Strahlen- und Kernphysik, Nussallee 14-16, Bonn, 53115, Germany , Bonn (Germany)
• 4 Institute of Experimental Particle Physics (ETP), Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Str. 1, Karlsruhe, 76131, Germany , Karlsruhe (Germany)
• 5 Johannes-Gutenberg-Universität Mainz, Institut für Physik, Mainz, 55099, Germany , Mainz (Germany)
• 6 Institute for Data Processing and Electronics (IPE), Karlsruhe Institute of Technology (KIT), Postfach 3640, Karlsruhe, 76021, Germany , Karlsruhe (Germany)
• 7 Institute for Nuclear Physics (IKP), Karlsruhe Institute of Technology (KIT), Postfach 3640, Karlsruhe, 76021, Germany , Karlsruhe (Germany)
• 8 Westfälische Wilhelms-Universität Münster, Institut für Kernphysik, Wilhelm-Klemm-Str. 9, Münster, 48149, Germany , Münster (Germany)
• 9 Institute for Nuclear Research of Russian Academy of Sciences, 60th October Anniversary Prospect 7a, Moscow, 117312, Russia , Moscow (Russia)
• 10 Institute for Technical Physics (ITeP), Karlsruhe Institute of Technology (KIT), Postfach 3640, Karlsruhe, 76021, Germany , Karlsruhe (Germany)
• 11 Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, Heidelberg, 69117, Germany , Heidelberg (Germany)
• 12 Max-Planck-Institut für Physik, Föhringer Ring 6, Munich, 80805, Germany , Munich (Germany)
• 13 Massachusetts Institute of Technology, Laboratory for Nuclear Science, 77 Massachusetts Ave, Cambridge, MA, 02139, USA , Cambridge (United States)
• 14 University of Washington, Center for Experimental Nuclear Physics and Astrophysics, and Dept. of Physics, Seattle, WA, 98195, USA , Seattle (United States)
• 15 Nuclear Physics Institute of the CAS, v. v. i., Řež, CZ-250 68, Czech Republic , Řež (Czechia)
• 16 University of Wuppertal, Department of Physics, Faculty of Mathematics und Natural Sciences, Gauss-Str. 20, Wuppertal, 42119, Germany , Wuppertal (Germany)
• 17 Carnegie Mellon University, Department of Physics, Pittsburgh, PA, 15213, USA , Pittsburgh (United States)
• 19 University of North Carolina, Department of Physics and Astronomy, Chapel Hill, NC, 27599, USA , Chapel Hill (United States)
• 20 Triangle Universities Nuclear Laboratory, Durham, NC, 27708, USA , Durham (United States)
• 21 Institute for Nuclear and Particle Astrophysics and Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA , Berkeley (United States)
• 22 University of Applied Sciences (HFD) Fulda, Leipziger Str. 123, Fulda, 36037, Germany , Fulda (Germany)
• 23 Case Western Reserve University, Department of Physics, Cleveland, OH, 44106, USA , Cleveland (United States)
• 24 Humboldt-Universität zu Berlin, Institut für Physik, Newtonstr. 15, Berlin, 12489, Germany , Berlin (Germany)
• 25 Karlsruhe Institute of Technology (KIT), Project, Process, and Quality Management (PPQ), Postfach 3640, Karlsruhe, 76021, Germany , Karlsruhe (Germany)
• 26 Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA , Oak Ridge (United States)
Type
Published Article
Journal
The European Physical Journal C
Publisher
Springer-Verlag
Publication Date
Sep 28, 2019
Volume
79
Issue
9
Identifiers
DOI: 10.1140/epjc/s10052-019-7320-4
Source
Springer Nature
The KATRIN experiment aims to measure the effective electron antineutrino mass mν¯e\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$m_{\overline{\nu }_e}$$\end{document} with a sensitivity of 0.2eV/c2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${0.2}\,{\hbox {eV}/\hbox {c}^2}$$\end{document} using a gaseous tritium source combined with the MAC-E filter technique. A low background rate is crucial to achieving the proposed sensitivity, and dedicated measurements have been performed to study possible sources of background electrons. In this work, we test the hypothesis that gamma radiation from external radioactive sources significantly increases the rate of background events created in the main spectrometer (MS) and observed in the focal-plane detector. Using detailed simulations of the gamma flux in the experimental hall, combined with a series of experimental tests that artificially increased or decreased the local gamma flux to the MS, we set an upper limit of 0.006count/s\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${0.006}\,{\hbox {count}/\hbox {s}}$$\end{document} (90% C.L.) from this mechanism. Our results indicate the effectiveness of the electrostatic and magnetic shielding used to block secondary electrons emitted from the inner surface of the MS.