Speaker
Description
Cosmogenic isotopes such as ${}^{9}\mathrm{Li}$ and ${}^{8}\mathrm{He}$ constitute important correlated backgrounds in the reactor antineutrino analysis of the JUNO experiment, since their $\beta+n$ decays can mimic inverse beta decay signals. In this work, we study the estimation and suppression of the ${}^{9}\mathrm{Li}$ background by using reconstructed muon-track information together with spallation-neutron (SPN) tagging. Muon samples are categorized according to the presence of SPN tags and valid reconstructed tracks. For each category, two-dimensional distributions of the time difference $\Delta t$ and the minimum spatial distance $d_{\min}$ between IBD candidates and associated muons are constructed and fitted to estimate the corresponding ${}^{9}\mathrm{Li}$ rate. In addition, Monte Carlo studies are performed to scan and optimize the veto strategy based on SPN and muon-track information. Preliminary results show that the inclusion of SPN spatial-correlation information significantly improves the identification of ${}^{9}\mathrm{Li}$-associated muons. The optimized muon track/SPN veto effectively suppresses the ${}^{9}\mathrm{Li}$ background while introducing only a small loss of IBD selection efficiency. This study provides useful input for the precise estimation of cosmogenic backgrounds and the optimization of veto strategies in JUNO.
| 请选择分会 | 中微子物理、粒子天体物理与宇宙学 |
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