Daya Bay Antineutrino Detector Gas System

TL;DR

The Daya Bay Antineutrino Detector gas system uses dry nitrogen to protect scintillators from contamination, monitor leaks, and ensure low background levels over a five-year experiment.

Contribution

This paper details the design and performance of a specialized gas system that safeguards detector integrity and minimizes backgrounds in a large-scale neutrino experiment.

Findings

Effective suppression of oxidation and radon infiltration

Continuous leak monitoring via oxygen and humidity levels

Reliable long-term operation over five years

Abstract

The Daya Bay Antineutrino Detector gas system is designed to protect the liquid scintillator targets of the antineutrino detectors against degradation and contamination from exposure to ambient laboratory air. The gas system is also used to monitor the leak tightness of the antineutrino detector assembly. The cover gas system constantly flushes the gas volumes above the liquid scintillator with dry nitrogen to minimize oxidation of the scintillator over the five year lifetime of the experiment. This constant flush also prevents the infiltration of radon or other contaminants into these detecting liquids keeping the internal backgrounds low. Since the Daya Bay antineutrino detectors are immersed in the large water pools of the muon veto system, other gas volumes are needed to protect vital detector cables or gas lines. These volumes are also purged with dry gas. Return gas is monitored for oxygen content and humidity to provide early warning of potentially damaging leaks. The design and performance of the Daya Bay Antineutrino Detector gas system is described.