Characterization of water-based liquid scintillator for Cherenkov and scintillation separation

Abstract

This paper presents measurements of the scintillation light yield and time profile of a number of concentrations of water-based liquid scintillator, formulated from linear alkylbenzene (LAB) and 2,5-Diphenyloxazole (PPO). The separation between Cherenkov and scintillation light is quantified using cosmic muons in the CHESS experiment for each formulation, and we discuss the prospects for large-scale detectors.

MeV-scale performance of water-based and pure liquid scintillator detectors

“…Measurements of these particular WbLS materials demonstrated a very fast timing response: with a rise time consistent with 0.1 ns, and a prompt decay time on the order of 2.5 ns. These measurements were confirmed with both x-ray excitation [48] and direct measurements with β and γ sources [14]. Since this fast time profile increases the overlap between the prompt Cherenkov and delayed scintillation signals, we also consider materials in which we delay the scintillation time profile by some defined amount, to study the impact of a "slow scintillator", for both pure LS and WbLS.…”

“…Properties for the pure LS detector are taken from measurements by the SNO+ collaboration [46,47]. We start by considering three WbLS target materials, based on bench-top measurements of properties reported in [14,48]. Each cocktail is a combination of water with LAB+PPO, with differing fractions of the organic component: 1, 5 and 10% concentration by mass.…”

“…One approach to achieving a hybrid detector is to deploy water-based liquid scintillator (WbLS) [1], a novel target medium that combines water with pure organic scintillator, thus leveraging the benefits of both scintillation and Cherenkov signals in a single detection medium, with the advantage of high optical transparency and, thus, good light collection. There is significant effort in the community to develop this technology, including target material development [1][2][3][4][5][6][7][8][9][10][11][12], demonstrations of Cherenkov light detection from scintillating media [13][14][15][16], demonstrations of spectral sorting [17,18], fast and high precision photon detector development [19][20][21][22][23][24][25][26], complementary development of reconstruction methods and particle identification techniques [27][28][29][30][31][32][33], and development of a practical purification system at UC Davis.…”

“…Each cocktail is a combination of water with LAB+PPO, with differing fractions of the organic component: 1, 5 and 10% concentration by mass. The light yield for each material is taken from [14], with the time profile and emission spectrum taken from [48]. Other properties are evaluated based on the composition of the material, as described in Sec.…”

Detecting the Diffuse Supernova Neutrino Background in the future Water-based Liquid Scintillator Detector Theia

“…The resulting liquid is an emulsion that consists of mycels (nanoscopic droplets) of organic material surrounded by a surfactant and dissolved in the bulk water. The main characteristics of state-of-the-art WbLS samples have been investigated in [17,18]: The light yield of the resulting WbLS is roughly proportional to its organic fraction. The attenuation length reached in the blue spectral range depends primarily on the properties of the diluted organic fraction and is assumed here very conservatively to ∼20 m [15].…”