摘要
In dark matter direct detection experiments,neutron is a serious source of background,which can mimic the dark matter-nucleus scattering signals.In this paper,we present an improved evaluation of the neutron background in the PandaX-II dark matter experiment by a novel approach.Instead of fully relying on the Monte Carlo simulation,the overall neutron background is determined from the neutron-induced high energy signals in the data.In addition,the probability of producing a dark-matter-like background per neutron is evaluated with a complete Monte Carlo generator,where the correlated emission of neutron(s)andγ(s)in the(α,n)reactions and spontaneous fissions is taken into consideration.With this method,the neutron backgrounds in the Run 9(26-ton-day)and Run 10(28-ton-day)data sets of PandaX-II are estimated to be(0.66±0.24)and(0.47±0.25)events,respectively.
In dark matter direct detection experiments, neutron is a serious source of background, which can mimic the dark matter-nucleus scattering signals. In this paper, we present an improved evaluation of the neutron background in the PandaX-II dark matter experiment by a novel approach. Instead of fully relying on the Monte Carlo simulation, the overall neutron background is determined from the neutron-induced high energy signals in the data. In addition, the probability of producing a dark-matter-like background per neutron is evaluated with a complete Monte Carlo generator, where the correlated emission of neutron(s) andγ(s) in the(α, n) reactions and spontaneous fissions is taken into consideration. With this method, the neutron backgrounds in the Run 9(26-ton-day) and Run 10(28-ton-day) data sets of PandaX-II are estimated to be(0.66±0.24) and(0.47±0.25) events,respectively.
基金
supported by the Double Top-class of Shanghai Jiao Tong University,the National Natural Science Foundation of China(Grant Nos.11435008,11505112,11525522,11775141,and 11755001)
the Ministry of Science and Technology of China(Grant No.2016YFA0400301)
the Office of Science and Technology,Shanghai Municipal Government(Grant Nos.11DZ2260700,16DZ2260200,and 18JC1410200)
the Key Laboratory for Particle Physics,Astrophysics and Cosmology,Ministry of Education,for important support
the Chinese Academy of Sciences Center for Excellence in Particle Physics(CCEPP)
Hongwen Foundation in Hong Kong
we thank the CJPL administration and the Yalong River Hydropower Development Company Ltd.for indispensable logistical support and other help.
