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arXiv · 2105.08533

First direct neutrino-mass measurement with sub-eV sensitivity

M. Aker·A. Beglarian·J. Behrens·A. Berlev·U. Besserer·B. Bieringer·F. Block·B. Bornschein·L. Bornschein·M. Böttcher·T. Brunst·T. S. Caldwell·R. M. D. Carney·L. La Cascio·S. Chilingaryan·W. Choi·K. Debowski·M. Deffert·M. Descher·D. Díaz Barrero·P. J. Doe·O. Dragoun·G. Drexlin·K. Eitel·E. Ellinger·R. Engel·S. Enomoto·A. Felden·J. A. Formaggio·F. M. Fränkle·G. B. Franklin·F. Friedel·A. Fulst·K. Gauda·W. Gil·F. Glück·R. Grössle·R. Gumbsheimer·V. Gupta·T. Höhn·V. Hannen·N. Haußmann·K. Helbing·S. Hickford·R. Hiller·D. Hillesheimer·D. Hinz·T. Houdy·A. Huber·A. Jansen·C. Karl·F. Kellerer·J. Kellerer·M. Klein·C. Köhler·L. Köllenberger·A. Kopmann·M. Korzeczek·A. Kovalík·B. Krasch·H. Krause·N. Kunka·T. Lasserre·T. L. Le·O. Lebeda·B. Lehnert·A. Lokhov·M. Machatschek·E. Malcherek·M. Mark·A. Marsteller·E. L. Martin·C. Melzer·A. Menshikov·S. Mertens·J. Mostafa·K. Müller·S. Niemes·P. Oelpmann·D. S. Parno·A. W. P. Poon·J. M. L. Poyato·F. Priester·M. Röllig·C. Röttele·R. G. H. Robertson·W. Rodejohann·C. Rodenbeck·M. Ryšavý·R. Sack·A. Saenz·P. Schäfer·A. Schaller·L. Schimpf·K. Schlösser·M. Schlösser·L. Schlüter·S. Schneidewind·M. Schrank·B. Schulz
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Abstract

We report the results of the second measurement campaign of the Karlsruhe Tritium Neutrino (KATRIN) experiment. KATRIN probes the effective electron anti-neutrino mass, $m_ν$, via a high-precision measurement of the tritium $β$-decay spectrum close to its endpoint at $18.6\,\mathrm{keV}$. In the second physics run presented here, the source activity was increased by a factor of 3.8 and the background was reduced by $25\,\%$ with respect to the first campaign. A sensitivity on $m_ν$ of $0.7\,\mathrm{eV/c^2}$ at $90\,\%$ confidence level (CL) was reached. This is the first sub-eV sensitivity from a direct neutrino-mass experiment. The best fit to the spectral data yields $m_ν^2 = (0.26\pm0.34)\,\mathrm{eV^4/c^4}$, resulting in an upper limit of $m_ν<0.9\,\mathrm{eV/c^2}$ ($90\,\%$ CL). By combining this result with the first neutrino mass campaign, we find an upper limit of $m_ν<0.8\,\mathrm{eV/c^2}$ ($90\,\%$ CL).

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M. Aker, A. Beglarian, J. Behrens, A. Berlev, U. Besserer, B. Bieringer, F. Block, B. Bornschein, L. Bornschein, M. Böttcher, T. Brunst, T. S. Caldwell, R. M. D. Carney, L. La Cascio, S. Chilingaryan, W. Choi, K. Debowski, M. Deffert, M. Descher, D. Díaz Barrero, P. J. Doe, O. Dragoun, G. Drexlin, K. Eitel, E. Ellinger, R. Engel, S. Enomoto, A. Felden, J. A. Formaggio, F. M. Fränkle, G. B. Franklin, F. Friedel, A. Fulst, K. Gauda, W. Gil, F. Glück, R. Grössle, R. Gumbsheimer, V. Gupta, T. Höhn, V. Hannen, N. Haußmann, K. Helbing, S. Hickford, R. Hiller, D. Hillesheimer, D. Hinz, T. Houdy, A. Huber, A. Jansen, C. Karl, F. Kellerer, J. Kellerer, M. Klein, C. Köhler, L. Köllenberger, A. Kopmann, M. Korzeczek, A. Kovalík, B. Krasch, H. Krause, N. Kunka, T. Lasserre, T. L. Le, O. Lebeda, B. Lehnert, A. Lokhov, M. Machatschek, E. Malcherek, M. Mark, A. Marsteller, E. L. Martin, C. Melzer, A. Menshikov, S. Mertens, J. Mostafa, K. Müller, S. Niemes, P. Oelpmann, D. S. Parno, A. W. P. Poon, J. M. L. Poyato, F. Priester, M. Röllig, C. Röttele, R. G. H. Robertson, W. Rodejohann, C. Rodenbeck, M. Ryšavý, R. Sack, A. Saenz, P. Schäfer, A. Schaller, L. Schimpf, K. Schlösser, M. Schlösser, L. Schlüter, S. Schneidewind, M. Schrank, B. Schulz. 2021-05-18. First direct neutrino-mass measurement with sub-eV sensitivity. https://arxiv.org/abs/2105.08533

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