Prospects of detecting the reactor (ν)over-bare-Ar coherent elastic scattering with a low-threshold dual-phase argon time projection chamber at Taishan

Background We propose to measure the coherent elastic neutrino-nucleus scattering (CEvNS) using a dual-phase liquid argon time projection chamber (TPC) with 200 kg fiducial mass. The detector is expected to be adjacent to the JUNO-TAO experiment and to be about 35 m from a reactor core with 4.6 GW thermal power at Taishan. The antineutrino flux is approximately 6 x 10(12)cm(-1)s(-1) at this location, leading to more than 11,000 coherent scattering events per day in the fiducial mass. Motivation The nuclear recoil energies concentrate in the sub-keV region, corresponding to less than ten ionization electrons in the liquid argon. The key question is how to veto and shield the background in the hall where the vertical overburden is about 5 m.w.e. And what is the signal count rate and the background rate. In addition, what physical parameters can be measured what is the sensitivity. Methods We used the Geant4 to simulate the backgrounds from cosmic ray muons and ambient radioactivity decays. And a veto and shielding design is presented. Then a chi(2) function is constructed and the sensitivity calculate package built to calculate the sensitivity of physical parameters. Results The detection of several ionization electrons can be achieved in the dual-phase TPC due to the large amplification in the gas region. With a feasible detection threshold of four ionization electrons, the signal rate is 955 per day. The detector is designed to be shielded well from cosmogenic backgrounds and ambient radioactivities to reach a 16% background-to-signal ratio in the energy region of interest. With the large CEvNS sample, the expected sensitivity of measuring the weak mixing angle sin(2)theta(w), and of limiting the neutrino magnetic moment are discussed. In addition, a synergy between the reactor antineutrino CEvNS experiment and the dark matter experiment is foreseen.

Automated summary

The study proposes to measure coherent elastic neutrino-nucleus scattering using a dual-phase liquid argon time projection chamber. The key challenges include handling background signals and increasing the signal count rate. Results show that the detector design is effective in shielding background signals, leading to good sensitivity in measuring physical parameters.