A Spectrometric Approach to Measuring the Rayleigh Scattering Length for Liquid Scintillator Detectors

TL;DR

This paper introduces a spectrometric method to measure wavelength-dependent Rayleigh scattering lengths in liquid scintillators, crucial for optimizing detector transparency and sensitivity.

Contribution

It presents a novel spectrometric approach based on Einstein-Smoluchowski theory to accurately measure scattering lengths in liquid scintillators.

Findings

Measured scattering length of LAB at 430 nm is 27.9 +/- 2.3 m.

Measured scattering length of EJ-309 at 430 nm is 6.1 +/- 0.6 m.

Method provides wavelength-dependent scattering data for LS materials.

Abstract

Good optical transparency is a fundamental requirement of liquid scintillator (LS) detectors. Characterizing the transparency of a liquid scintillator to its own emitted light is a key parameter to determine the overall sensitivity of a large-volume detector. The attenuation of light in an optical-pure LS is dominated by Rayleigh scattering, which poses an intrinsic limit to the transparency of LS. This work presents a spectrometric approach of measuring the wavelength-dependent scattering length of liquids by applying the Einstein-Smoluchowski theory to a measurement of scattered light intensity. The scattering lengths of linear alkyl benzene (LAB) and EJ309-base (Di-isopropylnaphthalene, DIN) were measured and are reported in the wavelength range of 410 to 520 nm. The spectral peak of scintillation light emitted by a nominal LS is around 430 nm at which the scattering length for LAB and EJ-309-base was determined to be 27.9 +/- 2.3 m and 6.1 +/- 0.6 m respectively.