Optical property measurements of lithium chloride aqueous solution for a novel solar neutrino experiment

TL;DR

This study evaluates the optical properties of lithium chloride aqueous solutions, demonstrating their suitability as a detection medium for a novel solar neutrino detector with enhanced light yield and long attenuation length.

Contribution

It provides detailed measurements of optical properties and introduces a wavelength shifter to improve light yield for lithium chloride-based neutrino detection.

Findings

Attenuation length reaches 50 meters at 430 nm

Little absorption in the sensitive wavelength range after treatment

Wavelength shifter enhances light yield

Abstract

The lithium chloride aqueous solution has great potential to be the detection medium of a novel solar neutrino detector. The nuclide \ce{^7 Li} provides a charged-current interaction channel with a high cross-section for the MeV-scale solar electron-neutrinos, enabling measurement of the solar neutrino spectrum. This work measures the optical properties and the light yields of a saturated lithium chloride solution. After adsorption with activated carbon and recrystallization, the solution shows little absorption in the sensitive wavelength range of the bialkali photomultipliers. The attenuation length is evaluated to reach 50 meters at 430 nm. In addition to being a pure Cherenkov detector medium, a wavelength shifter, carbostyril 124, is added to the LiCl aqueous solution. The compatibility and the enhancement of the light yield are confirmed, enabling the development of a water-based Cherenkov-enhanced lithium-rich detector.