Aachen 2019 – scientific programme

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T: Fachverband Teilchenphysik

T 8: Neutrinophysik I

T 8.3: Group Report

Monday, March 25, 2019, 16:40–17:00, S06

The search for eV sterile neutrinos with the STEREO experiment — •Christian Roca, Helena Almazán, Christian Buck, Manfred Lindner, and Stefan Schoppmann — Max-Planck-Institut für Kernphysik Heidelberg

In the last recent years, two unsolved anomalies have appeared during the study of the reactor neutrinos: one related to the neutrino spectral shape, and another to the absolute neutrino flux. The last one, known as the Reactor Antineutrino Anomaly (RAA), presents a deficit in the observed flux compared to the expected one. This anomaly could point to the existence of a light sterile neutrino participating in the oscillation phenomena.
The study of the nuclear reactor flux at very short baselines is a key to prove these hypothesis. The STEREO experiment observes neutrinos emitted from the compact, highly ²³⁵U enriched fuel element of the research reactor of the Institut Laue Langevin (Grenoble, France). The detector target is placed at only 10 meters of the reactor core, and in order to have an independent measurement of the neutrino spectrum, it is segmented in six independent cells providing a multiple baseline analysis. The recorded data during 113 (138) days of reactor turned on (off) analyzed and presented last year, are compatible with the null oscillation hypothesis and reject the original best-fit of the RAA at 98 % C.L. These results, and the most recent improvements of the second phase of data taking will be presented in this talk, providing a crucial input in the search of sterile neutrinos.