Rayleigh scattering of linear alkylbenzene in large liquid scintillator detectors

Abstract

Rayleigh scattering poses an intrinsic limit for the transparency of organic liquid scintillators. This work focuses on the Rayleigh scattering length of linear alkylbenzene (LAB), which will be used as the solvent of the liquid scintillator in the central detector of the Jiangmen Underground Neutrino Observatory. We investigate the anisotropy of the Rayleigh scattering in LAB, showing that the resulting Rayleigh scattering length will be significantly shorter than reported before. Given the same overall light attenuation, this will result in a more efficient transmission of photons through the scintillator, increasing the amount of light collected by the photosensors and thereby the energy resolution of the detector.

Spectroscopic study of light scattering in linear alkylbenzene for liquid scintillator neutrino detectors

“…Therefore, we can conclude that the depolarized part of light scattering in LAB is Rayleigh scattering even if we can not directly study the depolarization of light scattering of LAB at 430 nm, the main region of interest, due to the limitation of light source. Then the total light scattering length of Rayleigh scattering in LAB should be less than 30 m at 430 nm [18].…”

“…Because 430 nm is far from the absorption band of LAB [8], the weak absorption including the absorption/reemission of LAB at 430 nm is due to the optical purities [16,17]. Recently, it has been argued that the depolarized part of light scattering in LAB is also Rayleigh scattering because of molecular anisotropy [18]. Then the depolarization of light scattering in LAB is an intrinsic property of LAB.…”

“…The LAB in the JUNO experiment may not have the same absorption/reemission as the LAB in the previous experiment. Therefore, the total scattering length of LAB in the JUNO experiment will be guaranteed to be less than 30 m at 430 nm [18] only if the depolarized part of light scattering is Rayleigh scattering.…”

A complete optical model for liquid-scintillator detectors

“…In order to obtain the absorption curve (L abs ), the Rayleigh scattering effect (L Rayleigh ) should be subtracted from the measured attenuation (L att ). Recently the L Rayleigh of LAB was measured to be 27.0 m at 430 nm [17], and it is used in this work.…”

“…In this paper, we take the ternary LS composed of LAB, PPO and bis-MSB as an example, and introduce a novel optical model to simulate the light propagation in LS detector. Prior to this work, extensive measurements [13][14][15][16][17] have been performed to understand the photon transport and extract the optical properties of each LS component.…”