Fluorescence emission of the JUNO liquid scintillator

TL;DR

This paper characterizes the optical properties of JUNO's liquid scintillator, including emission spectrum, absorption length, and fluorescence timing, to support accurate neutrino detection and energy reconstruction.

Contribution

It provides detailed measurements of JUNO scintillator's optical characteristics, which are essential for optimizing detector performance.

Findings

Emission spectrum characterized across relevant wavelengths

Absorption length measured for scintillator components

Fluorescence decay time distribution obtained

Abstract

JUNO is a huge neutrino detector that will use 20 kton of organic liquid scintillator as its detection medium. The scintillator is a mixture of linear alkyl benzene (LAB), 2.5 g/L of 2,5-diphenyloxazole (PPO) and 3 mg/L of 1,4-Bis(2-methylstyryl)benzene (Bis-MSB). The main goal of JUNO is to determine the Neutrino Mass Ordering [1, 2, 3]. In order to achieve this purpose, good energy and position reconstruction is required, hence a complete understanding of the optical characteristics of the liquid scintillator is mandatory. In this paper we present the measurements on the JUNO scintillator emission spectrum, absorption length and fluorescence time distribution performed respectively with a spectrofluorimeter, a spectrophotometer and a custom made setup