Speaker
Description
The key to preparing a tellurium-loaded liquid scintillator (Te-LS) suitable for neutrinoless double beta decay (0νββ) searches lies in developing an organotellurium compound that dissolves uniformly and stably into the liquid scintillator (LS). We adopt a one-step synthesis route in which telluric acid (TeA) reacts directly with a diol to form an organotellurium-diol compound. This reaction is simple and streamlined and is readily scalable. 1,2-hexanediol, with its six-carbon chain, was selected as the reacting diol to ensure high solubility of the resulting product in LAB, the solvent used in the JUNO LS.
Two synthesis routes have been developed: (1) an azeotropic distillation method, and (2) a methanol-mediated room-temperature synthesis method. Te-LS prepared from the products of both routes exhibits excellent performance: extremely high solubility (Te loading > 5% in JUNO LS), excellent optical transparency (attenuation length of 20.1 ± 1.1 m for 1% Te-LAB via Route 2), good long-term stability (Route 1: > 3 years at 0.6% Te loading; Route 2: > 1 year at 1% and 3% Te loading), and a light yield with further room for improvement (80% ± 2% relative to unloaded LS of the same formulation, at 0.5% Te loading).
Ongoing work is targeting a 20-ton Te-LS demonstration, aiming to further improve Te-LS performance, reduce the difficulty of large-scale production, and enhance operational safety. In parallel, we are pursuing radiopurification of TeA, a critical step for controlling the radiopurity of Te-LS.