Radioactivity control strategy for the JUNO detector
A. C. Abusleme Hoffman, Thomas Adam, S. Ahmad, Rizwan Ahmed, S. Aiello, M. Akram, Fengpeng An, Qi An, Giuseppe Andronico, Н. Анфимов, V. Antonelli, Tatiana Antoshkina, Burin Asavapibhop, J. P. A. M. de André, Didier Auguste, Andrej Babič, W. Baldini, Andrea Barresi, D. Basilico, E. Baussan, M. Bellato, Antonio Bergnoli, Thilo Birkenfeld, Sylvie Blin, David Blum, S.C. Blyth, Anastasia Bolshakova, M. Bongrand, Clément Bordereau, D. Breton, A. Brigatti, R. Brugnera, Riccardo Bruno, A. Budano, Mario Buscemi, José Busto, Ilya Butorov, J. Busenitz, Hao Cai, X. Cai, Yanke Cai, Zhiyan Cai, Antonio Cammi, Agustín Campeny, Chuanya Cao, Guofu Cao, Jun Cao, R. Caruso, C. Cerna, J. F. Chang, Yun Chang, Pingping Chen, Po-An Chen, Shaomin Chen, Xurong Chen, Yiwen Chen, Yixue Chen, Yu Chen, Zhang Chen, Jie Cheng, Yaping Cheng, Alexey Chetverikov, D. Chiesa, P. Chimenti, A. Chukanov, Gérard Claverie, Catia Clementi, Barbara Clerbaux, Selma Conforti Di Lorenzo, Daniele Corti, O. Cremonesi, F. Dal Corso, Olivia Dalager, C. De La Taille, Jiawei Deng, Zhi Deng, Ziyan Deng, Wilfried Depnering, Marco Diaz, Xuefeng Ding, Yayun Ding, Bayu Dirgantara, Sergey Dmitrievsky, Tadeáš Dohnal, Dmitry Dolzhikov, Georgy Donchenko, J. Dong, E. Doroshkevich, M. Dracos, Frédéric Druillole, Shuxian Du, S. Dusini, Martin Dvořák, T. Enqvist, Heike Enzmann, Andrea Fabbri, L. Fajt, Donghua Fan, Lei Fan, J. Fang
Abstract
A bstract JUNO is a massive liquid scintillator detector with a primary scientific goal of determining the neutrino mass ordering by studying the oscillated anti-neutrino flux coming from two nuclear power plants at 53 km distance. The expected signal anti-neutrino interaction rate is only 60 counts per day (cpd), therefore a careful control of the background sources due to radioactivity is critical. In particular, natural radioactivity present in all materials and in the environment represents a serious issue that could impair the sensitivity of the experiment if appropriate countermeasures were not foreseen. In this paper we discuss the background reduction strategies undertaken by the JUNO collaboration to reduce at minimum the impact of natural radioactivity. We describe our efforts for an optimized experimental design, a careful material screening and accurate detector production handling, and a constant control of the expected results through a meticulous Monte Carlo simulation program. We show that all these actions should allow us to keep the background count rate safely below the target value of 10 Hz (i.e. ∼ 1 cpd accidental background) in the default fiducial volume, above an energy threshold of 0.7 MeV.