Neutron-induced nuclear recoil background in the PandaX-4T experiment* *Supported in part by grants from National Science Foundation of China (12090061, 12005131, 11905128, 11925502), the Ministry of Science and Technology of China (2016YFA0400301), and by the Office of Science and Technology, Shanghai Municipal Government (18JC1410200)

Abstract

Neutron-induced nuclear recoil background is critical to dark matter searches in the PandaX-4T liquid xenon experiment. In this study, we investigate the features of neutron background in liquid xenon and evaluate its contribution in single scattering nuclear recoil events using three methods. The first method is fully based on Monte Carlo simulations. The last two are data-driven methods that also use multiple scattering signals and high energy signals in the data. In the PandaX-4T commissioning data with an exposure of 0.63 tonne-year, all these methods give a consistent result, i.e., there are neutron-induced backgrounds in the dark matter signal region within an approximated nuclear recoil energy window between 5 and 100 keV.