Double Chooz

Double Chooz (pronounced: [ˈdʌb.əɫ ʃo]DUB-əl shoh) is a short-baseline neutrino oscillation experiment in Chooz, France. Its goal is to measure or set a limit on the θ₁₃ mixing angle, a neutrino oscillation parameter responsible for changing electron neutrinos into other neutrinos. The experiment uses reactors of the Chooz Nuclear Power Plant as a neutrino source and measures the flux of neutrinos they receive. To accomplish this, Double Chooz has a set of two detectors situated 400 meters and 1050 meters from the reactors. Double Chooz is a successor to the CHOOZ experiment; one of its detectors occupies the same site as its predecessor. Until January 2015 all data has been collected using only the far detector. The near detector was completed in September 2014, after construction delays and is taking physics data since beginning of 2015.

Double Chooz uses two identical Gadolinium-doped liquid scintillator detectors placed around the 4.25 GW thermal power reactors to measure antineutrino disappearance. The two detectors are aptly referred to as "near", 400 meters from the reactor; and "far", 1,050 meters from the reactor. The far detector is placed inside a hill such that there is a 300 meters of water equivalent of shielding from cosmic muons. The detector itself is a calorimetric liquid scintillator consisting of four concentric cylindrical vessels.

The innermost vessel is made of acrylic plastic and has a diameter of 230 cm, a height of 245.8 cm, and a thickness of 0.8 cm. This chamber is filled with 10,000 liters of gadolinium (Gd) loaded (1 gram/liter) liquid scintillator; it is the neutrino target. The next layer out is the γ-catcher. It surrounds the neutrino target with a 55 cm thick layer of Gd-free liquid scintillator. The casing for the γ-catcher is 12 cm thick and made of the same material as the neutrino catcher. The materials are chosen so that both of these vessels are transparent to photons with a wavelength greater than 400 nm.

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