Double Chooz was a short-baseline neutrino oscillation experiment in Chooz, France. Its goal was 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 used the Chooz Nuclear Power Plant reactors as a neutrino source and measured the flux of neutrinos from them. To accomplish this, Double Chooz had a set of two detectors situated 400 meters and 1050 meters from the reactors. Double Chooz was a successor to the Chooz experiment; one of its detectors occupies the same site as its predecessor. Until January 2015 all data had been collected using only the far detector. The near detector was completed in September 2014, after construction delays,[1] and started taking data at the beginning of 2015. Both detectors stopped taking data in late December 2017.