Search for light sterile neutrinos with the Double Chooz experiment
| Autor: | Hellwig, Denise |
|---|---|
| Přispěvatelé: | Wiebusch, Christopher, Stahl, Achim |
| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: | |
| Zdroj: | Aachen 1 Online-Ressource (xviii, 160, XI Seiten) (2020). doi:10.18154/RWTH-2020-05375 = Dissertation, RWTH Aachen University, 2020 |
| Popis: | Dissertation, RWTH Aachen University, 2020; Dissertation, RWTH Aachen University, 2020 The Double Chooz experiment is a reactor antineutrino disappearance experiment located in Chooz, France. It was designed to measure the neutrino mixing angle $\theta_{13}$. The experiment is composed of two liquid scintillator detectors of almost identical design that were able to identify electron antineutrinos from the two Chooz B reactor cores by the unique signal of the inverse beta decay. The far detector at an average baseline of 1050 m from the two reactor cores was in operation from April 2011 to the beginning of 2018. The near detector at an average baseline of 400 m has been operating from the beginning of 2015 to the beginning of 2018. A neutrino oscillation analysis can be setup independently from any theoretical model of the reactor neutrino flux utilizing the different baselines of near and far detector relying only on the comparison of near and far detector data. In doing so, all correlated systematics cancel and the analysis is protected against potential bias due to a mismatch of reactor neutrino prediction and data. Apart from its original design goal to measure $\theta_{13}$, Double Chooz is sensitive to so called light sterile neutrinos. Sterile neutrinos are neutrino states that do not take part in the weak interaction but may lead to additional disappearance of the known neutrino states, if they mix with the latter. That mixing is described by additional neutrino squared mass differences and mixing angles. The 3+1 model assumes one additional sterile state. Here, Double Chooz is sensitive to the new mixing angle $\theta_{14}$ depending on the new squared mass difference $\Delta m^2_{41}$ if it is in the range of $0.003\,\mathrm{eV}^2 \lesssim \Delta m^2_{41} \lesssim 0.3\, \mathrm{eV}^2$. This work presents the analysis of Double Chooz data with respect to sterile neutrinos. A Poissonian likelihood fit approach not relying on reactor model predictions is used. It is found that the Double Chooz data is with a p-value of $24.7\% \pm 2.2\%$ consistent with the no-sterile (i.e. $\theta_{14}=0$) hypothesis. The upper limit on $\sin^2 2 \theta_{14}$ at 95% confidence level is given as a function of $\Delta m^2_{41}$. |
| Databáze: | OpenAIRE |
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