Search

Sterile neutrinos emerge in minimal extensions of the Standard Model which can solve a number of open questions in astroparticle physics. For example, sterile neutrinos in the keV-mass range are viable dark matter candidates. Their existence would lead to a kink-like distortion in the tritium $\beta$-decay spectrum. In this work we report about the instrumentation of the Troitsk nu-mass experiment with a 7-pixel TRISTAN prototype detector and measurements in both differential and integral mode. The combination of the two modes is a key requirement for a precise sterile neutrino search, as both methods are prone to largely different systematic uncertainties. Thanks to the excellent performance of the TRISTAN detector at high rates, a sterile neutrino search up to masses of about 6 keV could be performed, which enlarges the previous accessible mass range by a factor of 3. Upper limits on the neutrino mixing amplitude in the mass range < 5.6 keV (differential) and < 6.6 keV (integral) are presented. These results demonstrate the feasibility of a sterile neutrino search as planned in the upgrade of the KATRIN experiment with the final TRISTAN detector and read-out system., Comment: 17 pages, 10 figures, Tristan in Troitsk phase 2 and 3

The KATRIN (Karlsruhe Tritium Neutrino) experiment investigates the energetic endpoint of the tritium $\beta$-decay spectrum to determine the effective mass of the electron anti-neutrino with a precision of $200\,\mathrm{meV}$ ($90\,\%$ C.L.) after an effective data taking time of three years. The TRISTAN (tritium $\beta$-decay to search for sterile neutrinos) group aims to detect a sterile neutrino signature by measuring the entire tritium $\beta$-decay spectrum with an upgraded KATRIN system. One of the greatest challenges is to handle the high signal rates generated by the strong activity of the KATRIN tritium source. Therefore, a novel multi-pixel silicon drift detector is being designed, which is able to handle rates up to $10^{8}\,\mathrm{cps}$ with an excellent energy resolution of $<200\,\mathrm{eV}$ (FWHM) at $10\,\mathrm{keV}$. This work gives an overview of the ongoing detector development and test results of the first seven pixel prototype detectors., Comment: 5 pages, 6 figures, Proceedings of the 7th International Pontecorvo Neutrino Physics School