  This article describes the setup and performance of the near and far
detectors in the Double Chooz experiment. The electron antineutrinos of the
Chooz nuclear power plant were measured in two identically designed detectors
with different average baselines of about 400 m and 1050 m from the two reactor
cores. Over many years of data taking the neutrino signals were extracted from
interactions in the detectors with the goal of measuring a fundamental
parameter in the context of neutrino oscillation, the mixing angle {\theta}13.
The central part of the Double Chooz detectors was a main detector comprising
four cylindrical volumes filled with organic liquids. From the inside towards
the outside there were volumes containing gadolinium-loaded scintillator,
gadolinium-free scintillator, a buffer oil and, optically separated, another
liquid scintillator acting as veto system. Above this main detector an
additional outer veto system using plastic scintillator strips was installed.
The technologies developed in Double Chooz were inspiration for several other
antineutrino detectors in the field. The detector design allowed implementation
of efficient background rejection techniques including use of pulse shape
information provided by the data acquisition system. The Double Chooz detectors
featured remarkable stability, in particular for the detected photons, as well
as high radiopurity of the detector components.
