Dark matter direct search sensitivity of the PandaX-4T experiment

The PandaX-4T experiment, a 4-ton scale dark matter direct detection experiment, is being planned at the China Jinping Un- derground Laboratory. In this paper we present a simulation study of the expected background in this experiment. In a 2.8-ton fiducial mass and the signal region between 1–10 keV electron equivalent energy, the total electron recoil background is found to be 4:9 × 10 −5 kg −1 d −1 keV −1 . The nuclear recoil background in the same region is 2:8 × 10 −7 kg −1 d −1 keV −1 . With an exposure of 5.6 ton-years, the sensitivity of PandaX-4T could reach a minimum spin-independent dark matter-nucleon cross section of 6 × 10 −48 cm 2 at a dark matter mass of 40 GeV/ c 2 .