Ultra-trace analysis of U and Th in organic liquid scintillators with high sensitivity
Abstract
Rare event searches demand extremely low background levels, necessitating ever-advancing screening techniques to enhance sensitivity. Liquid scintillators are highly attractive as detector media due to their inherent radiopurity and scalability in mass. In this work, we present a screening procedure to measure ultra-trace concentrations of natural contaminants -- U and Th -- with sensitivities at the \qty{E-15}{g/g} level. Our method combines neutron activation analysis with radiochemical techniques, followed by \bg\ coincidence spectroscopy to minimize interference backgrounds. This approach achieves sensitivities of \qty{0.65E-15}{g/g} for U and \qty{2.3E-15}{g/g} for Th, among the best reported worldwide. Potential pathways for further sensitivity improvements are outlined in the conclusions.
Keywords
Cite
@article{arxiv.2512.08988,
title = {Ultra-trace analysis of U and Th in organic liquid scintillators with high sensitivity},
author = {A. Barresi and D. Chiesa and D. Merli and M. Nastasi and S. Nisi and E. Previtali and M. Sisti and M. Borghesi and A. Cammi and C. Coletta and G. Ferrante and L. Loi and G. Andronico and V. Antonelli and D. Basilico and M. Beretta and A. Bergnoli and A. Brigatti and R. Brugnera and R. Bruno and A. Budano and B. Caccianiga and V. Cerrone and R. Caruso and C. Clementi and L. V. D'Auria and S. Dusini and A. Fabbri and G. Felici and A. Garfagnini and M. G. Giammarchi and N. Giudice and A. Gavrikov and M. Grassi and N. Guardone and F. Houria and C. Landini and L. Lastrucci and I. Lippi and P. Lombardi and F. Mantovani and S. M. Mari and A. Martini and L. Miramonti and M. Montuschi and D. Orestano and F. Ortica and A. Paoloni and L. Pelicci and E. Percalli and F. Petrucci and G. Ranucci and A. C. Re and B. Ricci and A. Romani and P. Saggese and A. Serafini and C. Sirignano and L. Stanco and E. Stanescu Farilla and V. Strati and M. D. C Torri and C. Tuve' and C. Venettacci and G. Verde and L. Votano},
journal= {arXiv preprint arXiv:2512.08988},
year = {2025}
}