The Daya Bay Antineutrino Detector Filling System and Liquid Mass Measurement

TL;DR

The paper details the design and performance of a precise filling system for antineutrino detectors at Daya Bay, enabling accurate measurement of liquid masses critical for neutrino oscillation experiments.

Contribution

It introduces a novel filling system that achieves sub-0.02% precision in liquid target mass measurement for neutrino detectors.

Findings

Achieved target mass measurement precision of <0.02%.

Demonstrated reliable operation of the filling system.

Enhanced the accuracy of neutrino oscillation measurements.

Abstract

The Daya Bay Reactor Neutrino Experiment has measured the neutrino mixing angle \theta_{13} to world-leading precision. The experiment uses eight antineutrino detectors filled with 20-tons of gadolinium-doped liquid scintillator to detect antineutrinos emitted from the Daya Bay nuclear power plant through the inverse beta decay reaction. The precision measurement of sin^{2}2\theta_{13} relies on the relative antineutrino interaction rates between detectors at near (400 m) and far (roughly 1.8 km) distances from the nuclear reactors. The measured interaction rate in each detector is directly proportional to the number of protons in the liquid scintillator target. A precision detector filling system was developed to simultaneously fill the three liquid zones of the antineutrino detectors and measure the relative target mass between detectors to <0.02%. This paper describes the design, operation, and performance of the system and the resulting precision measurement of the detectors' target liquid masses.