Long-Term Testing and Properties of Acrylic for the Daya Bay Antineutrino Detectors

TL;DR

This paper reports on long-term testing of acrylic used in Daya Bay antineutrino detectors, focusing on its stability and interactions under operational conditions to ensure detector performance over five years.

Contribution

It provides detailed long-term mechanical and optical property data of acrylic in conditions mimicking actual detector environments, a novel contribution for neutrino detector materials.

Findings

Acrylic maintains optical clarity over time.

Acrylic exhibits stable mechanical properties under operational conditions.

No adverse interactions between acrylic and detector liquids were observed.

Abstract

The Daya Bay reactor antineutrino experiment has recently measured the neutrino mixing parameter sin22{\theta}13 by observing electron antineutrino disappearance over kilometer-scale baselines using six antineutrino detectors at near and far distances from reactor cores at the Daya Bay nuclear power complex. Liquid scintillator contained in transparent target vessels is used to detect electron antineutrinos via the inverse beta-decay reaction. The Daya Bay experiment will operate for about five years yielding a precision measurement of sin22{\theta}13. We report on long-term studies of poly(methyl methacrylate) known as acrylic, which is the primary material used in the fabrication of the target vessels for the experiment's antineutrino detectors. In these studies, acrylic samples are subjected to gaseous and liquid environmental conditions similar to those experienced during construction, transport, and operation of the Daya Bay acrylic target vessels and detectors. Mechanical and optical stability of the acrylic as well as its interaction with detector liquids is reported.