Precision measurement of the electron energy-loss function in tritium and deuterium gas for the KATRIN experiment

Journal Article · Mon Jul 05 00:00:00 EDT 2021 · European Physical Journal. C, Particles and Fields

DOI:https://doi.org/10.1140/epjc/s10052-021-09325-z· OSTI ID:1805117

Aker, M.; Beglarian, A.; Behrens, J.; Berlev, A.; Besserer, U.; Bieringer, B.; Block, F.; Bornschein, B.; Bornschein, L.; Böttcher, M.; Brunst, T.; Caldwell, T. S.; Carney, R. M. D.; Chilingaryan, S.; Choi, W.; Debowski, K.; Deffert, M.; Descher, M.; Barrero, D. Díaz; Doe, P. J. ; Dragoun, O.; Drexlin, G.; Edzards, F.; Eitel, K.; Ellinger, E.; Miniawy, A. El; Engel, R.; Enomoto, S.; Felden, A.; Formaggio, J. A.; Fränkle, F. M.; Franklin, G. B.; Friedel, F.; Fulst, A.; Gauda, K.; Gil, W.; Glück, F.; Groh, S.; Grössle, R.; Gumbsheimer, R.; Hannen, V.; Haußmann, N.; Heizmann, F.; Helbing, K.; Hickford, S.; Hiller, R.; Hillesheimer, D.; Hinz, D.; Höhn, T.; Houdy, T.; Huber, A.; Jansen, A.; Karl, C.; Kellerer, J.; Kleesiek, M.; Klein, M.; Köhler, C.; Köllenberger, L.; Kopmann, A.; Korzeczek, M.; Kovalík, A.; Krasch, B.; Krause, H.; Kunka, N.; Lasserre, T.; La Cascio, L.; Lebeda, O.; Lehnert, B.; Le, T. L.; Lokhov, A.; Machatschek, M.; Malcherek, E.; Mark, M.; Marsteller, A.; Martin, E. L.; Meier, M.; Melzer, C.; Menshikov, A.; Mertens, S.; Mostafa, J.; Müller, K.; Niemes, S.; Oelpmann, P.; Parno, D. S.; Poon, A. W. P.; Poyato, J. M. L.; Priester, F.; Ranitzsch, P. C. -O.; Robertson, R. G. H.; Rodejohann, W.; Rodenbeck, C.; Röllig, M.; Röttele, C.; Ryšavý, M.; Sack, R.; Saenz, A.; Schäfer, P.; Schaller, A.; Schimpf, L.; Schlösser, K.; Schlösser, M.; Schlüter, L.; Schneidewind, S.; Schrank, M.; Schulz, B.; Schwachtgen, C.; Šefčík, M.; Seitz-Moskaliuk, H.; Sibille, V.; Siegmann, D.; Slezák, M.; Steidl, M.; Sturm, M.; Sun, M.; Tcherniakhovski, D.; Telle, H. H.; Thorne, L. A.; Thümmler, T.; Titov, N.; Tkachev, I.; Trost, N.; Urban, K.; Valerius, K.; Vénos, D.; Hernández, A. P. Vizcaya; Weinheimer, C.; Welte, S.; Wendel, J.; Wilkerson, J. F.; Wolf, J.; Wüstling, S.; Xu, W.; Yen, Y. -R.; Zadoroghny, S.; Zeller, G.

Abstract

The KATRIN experiment is designed for a direct and model-independent determination of the effective electron anti-neutrino mass via a high-precision measurement of the tritium $$$$\upbeta $$$$ $\beta$ -decay endpoint region with a sensitivity on $$$$m_\nu $$$$ $m_{\nu }$ of 0.2  $$$$\hbox {eV}/\hbox {c}^2$$$$ $\text{eV}/{\text{c}}^2$ (90% CL). For this purpose, the $$$$\upbeta $$$$ $\beta$ -electrons from a high-luminosity windowless gaseous tritium source traversing an electrostatic retarding spectrometer are counted to obtain an integral spectrum around the endpoint energy of 18.6 keV. A dominant systematic effect of the response of the experimental setup is the energy loss of $$$$\upbeta $$$$ $\beta$ -electrons from elastic and inelastic scattering off tritium molecules within the source. We determined the energy-loss function in-situ with a pulsed angular-selective and monoenergetic photoelectron source at various tritium-source densities. The data was recorded in integral and differential modes; the latter was achieved by using a novel time-of-flight technique. We developed a semi-empirical parametrization for the energy-loss function for the scattering of 18.6-keV electrons from hydrogen isotopologs. This model was fit to measurement data with a 95% $$$$\hbox {T}_2$$$$ ${\text{T}}_2$ gas mixture at 30 K, as used in the first KATRIN neutrino-mass analyses, as well as a $$$$\hbox {D}_2$$$$ ${\text{D}}_2$ gas mixture of 96% purity used in KATRIN commissioning runs. The achieved precision on the energy-loss function has abated the corresponding uncertainty of $$$$\sigma (m_\nu ^2)< {{10}^{-2}}{\hbox {eV}^{2}}$$$$ $\sigma \left(m_{\nu }^2\right)<{10}^{-2}{\text{eV}}^2$ [1] in the KATRIN neutrino-mass measurement to a subdominant level.

• Sponsoring Organization: USDOE
• Grant/Contract Number: FG02-97ER41020; FG02-94ER40818; SC0004036
• OSTI ID: 1805117
• Alternate ID(s): OSTI ID: 1820603; OSTI ID: 1834001; OSTI ID: 23086113; OSTI ID: 1907695
• Journal Information: European Physical Journal. C, Particles and Fields, Journal Name: European Physical Journal. C, Particles and Fields Journal Issue: 7 Vol. 81; ISSN 1434-6044
• Publisher: Springer Science + Business Media
• Country of Publication: Germany
• Language: English