Temperature-dependent fluorescence emission spectra of acrylic (PMMA) and tetraphenyl butadiene (TPB) excited with UV light

TL;DR

This study investigates how the fluorescence emission spectra of acrylic (PMMA) and TPB change with temperature under UV excitation, revealing increased fluorescence intensity at lower temperatures relevant for dark matter experiments.

Contribution

It provides the first detailed temperature-dependent fluorescence spectra of PMMA used in dark matter detectors, including comparison with TPB as a reference.

Findings

PMMA fluorescence intensity increases as temperature decreases from 300K to 4K.

Fluorescence spectra of PMMA and TPB are characterized at various low temperatures.

PMMA exhibits measurable fluorescence at cryogenic temperatures, impacting its use in scintillation detectors.

Abstract

Acrylic (poly(methyl methacrylate) or PMMA) is commonly used as a vessel to hold scintillating liquids in rare-event searches. Certain types of PMMA can fluoresce with a low efficiency at room temperature. We have investigated the fluorescence spectra under 280nm ultraviolet (UV) excitation of the PMMA used in the DEAP dark matter search at various low temperatures. Fluorescence of this PMMA is observed, with an increasing intensity as the sample is cooled from a temperature of 300K down to 4K. The common wavelength-shifter tetraphenyl butadiene (TPB) is also measured for use as a reference.