Valerian Sibille - "Cosmogenic background studies in the Double Chooz experiment"

par Dr Cecile Jollet (IPHC/Universite de Strasbourg)

vendredi 9 déc. 2016, 11:00 → 12:15 Europe/Paris

2e étage, Salle Pistache (IPHC, Bât 27)

The Double Chooz experiment aims at accurately measuring the value of the θ₁₃ neutrino mixing angle. To do so, the experiment makes the most of two identical detectors – filled with gadolinium-loaded liquid scintillator – observing the electron antineutrinos released by the two nuclear reactors of the French Chooz power plant. The θ₁₃ mixing parameter leads to an energy dependent disappearance of the antineutrinos as they propagate from the nuclear cores to the detection sites, which allows for a fit of the sin²(2θ₁₃) value. A relative measurement and a good understanding of the various backgrounds has allowed the Double Chooz collaboration to present recent and robust assessments of the mixing parameter: sin²(2θ₁₃) = 0.111+/-0.018 (March) followed by sin²(2θ₁₃) = 0.119+/-0.016 (September).

The seminar will introduce the neutrino oscillation phenomenon, present the experimental site and detection principle, before focusing on the main source of background for the experiment: the decay of cosmogenic isotopes. The latter are produced in the detector by muon-induced spallation reactions; both their energy spectrum and their daily rates are of paramount importance to the experiment, thereby demanding thorough analyses or simulations. Another significant impairment of the experiment, the uncertainty on the number of target protons, will be highlighted, before the final θ₁₃ results are discussed.

 

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