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arXiv · 2503.00968

Simulation of the Background from $^{13}$C$(α, n)^{16}$O Reaction in the JUNO Scintillator

JUNO Collaboration·Thomas Adam·Kai Adamowicz·Shakeel Ahmad·Rizwan Ahmed·Sebastiano Aiello·Fengpeng An·Costas Andreopoulos·Giuseppe Andronico·Nikolay Anfimov·Vito Antonelli·Tatiana Antoshkina·João Pedro Athayde Marcondes de André·Didier Auguste·Weidong Bai·Nikita Balashov·Andrea Barresi·Davide Basilico·Eric Baussan·Marco Beretta·Antonio Bergnoli·Nikita Bessonov·Daniel Bick·Lukas Bieger·Svetlana Biktemerova·Thilo Birkenfeld·Simon Blyth·Anastasia Bolshakova·Mathieu Bongrand·Matteo Borghesi·Dominique Breton·Augusto Brigatti·Riccardo Brugnera·Riccardo Bruno·Marcel Büchner·Antonio Budano·Jose Busto·Anatael Cabrera·Barbara Caccianiga·Hao Cai·Xiao Cai·Yanke Cai·Zhiyan Cai·Stéphane Callier·Steven Calvez·Antonio Cammi·Chuanya Cao·Guofu Cao·Jun Cao·Yaoqi Cao·Rossella Caruso·Cédric Cerna·Vanessa Cerrone·Jinfan Chang·Yun Chang·Auttakit Chatrabhuti·Chao Chen·Guoming Chen·Jiahui Chen·Jian Chen·Jing Chen·Junyou Chen·Pingping Chen·Shaomin Chen·Shiqiang Chen·Xin Chen·Yiming Chen·Yixue Chen·Yu Chen·Ze Chen·Zhangming Chen·Zhiyuan Chen·Jie Cheng·Yaping Cheng·Yu Chin Cheng·Alexander Chepurnov·Alexey Chetverikov·Davide Chiesa·Pietro Chimenti·Po-Lin Chou·Ziliang Chu·Artem Chukanov·Gérard Claverie·Catia Clementi·Barbara Clerbaux·Claudio Coletta·Selma Conforti Di Lorenzo·Simon Csakli·Chenyang Cui·Olivia Dalager·Christophe De La Taille·Zhi Deng·Ziyan Deng·Xiaoyu Ding·Xuefeng Ding·Yayun Ding·Bayu Dirgantara·Carsten Dittrich·Sergey Dmitrievsky·David Doerflinger

Abstract

Large-scale organic liquid scintillator detectors are highly efficient in the detection of MeV-scale electron antineutrinos. These signal events can be detected through inverse beta decay on protons, which produce a positron accompanied by a neutron. A noteworthy background for antineutrinos coming from nuclear power reactors and from the depths of the Earth (geoneutrinos) is generated by ($α, n$) reactions. In organic liquid scintillator detectors, $α$ particles emitted from intrinsic contaminants such as $^{238}$U, $^{232}$Th, and $^{210}$Pb/$^{210}$Po, can be captured on $^{13}$C nuclei, followed by the emission of a MeV-scale neutron. Three distinct interaction mechanisms can produce prompt energy depositions preceding the delayed neutron capture, leading to a pair of events correlated in space and time within the detector. Thus, ($α, n$) reactions represent an indistinguishable background in liquid scintillator-based antineutrino detectors, where their expected rate and energy spectrum are typically evaluated via Monte Carlo simulations. This work presents results from the open-source SaG4n software, used to calculate the expected energy depositions from the neutron and any associated de-excitation products. Also simulated is a detailed detector response to these interactions, using a dedicated Geant4-based simulation software from the JUNO experiment. An expected measurable $^{13}$C$(α, n)^{16}$O event rate and reconstructed prompt energy spectrum with associated uncertainties, are presented in the context of JUNO, however, the methods and results are applicable and relevant to other organic liquid scintillator neutrino detectors.

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JUNO Collaboration, Thomas Adam, Kai Adamowicz, Shakeel Ahmad, Rizwan Ahmed, Sebastiano Aiello, Fengpeng An, Costas Andreopoulos, Giuseppe Andronico, Nikolay Anfimov, Vito Antonelli, Tatiana Antoshkina, João Pedro Athayde Marcondes de André, Didier Auguste, Weidong Bai, Nikita Balashov, Andrea Barresi, Davide Basilico, Eric Baussan, Marco Beretta, Antonio Bergnoli, Nikita Bessonov, Daniel Bick, Lukas Bieger, Svetlana Biktemerova, Thilo Birkenfeld, Simon Blyth, Anastasia Bolshakova, Mathieu Bongrand, Matteo Borghesi, Dominique Breton, Augusto Brigatti, Riccardo Brugnera, Riccardo Bruno, Marcel Büchner, Antonio Budano, Jose Busto, Anatael Cabrera, Barbara Caccianiga, Hao Cai, Xiao Cai, Yanke Cai, Zhiyan Cai, Stéphane Callier, Steven Calvez, Antonio Cammi, Chuanya Cao, Guofu Cao, Jun Cao, Yaoqi Cao, Rossella Caruso, Cédric Cerna, Vanessa Cerrone, Jinfan Chang, Yun Chang, Auttakit Chatrabhuti, Chao Chen, Guoming Chen, Jiahui Chen, Jian Chen, Jing Chen, Junyou Chen, Pingping Chen, Shaomin Chen, Shiqiang Chen, Xin Chen, Yiming Chen, Yixue Chen, Yu Chen, Ze Chen, Zhangming Chen, Zhiyuan Chen, Jie Cheng, Yaping Cheng, Yu Chin Cheng, Alexander Chepurnov, Alexey Chetverikov, Davide Chiesa, Pietro Chimenti, Po-Lin Chou, Ziliang Chu, Artem Chukanov, Gérard Claverie, Catia Clementi, Barbara Clerbaux, Claudio Coletta, Selma Conforti Di Lorenzo, Simon Csakli, Chenyang Cui, Olivia Dalager, Christophe De La Taille, Zhi Deng, Ziyan Deng, Xiaoyu Ding, Xuefeng Ding, Yayun Ding, Bayu Dirgantara, Carsten Dittrich, Sergey Dmitrievsky, David Doerflinger. 2025-05-02. Simulation of the Background from $^{13}$C$(α, n)^{16}$O Reaction in the JUNO Scintillator. https://arxiv.org/abs/2503.00968

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