Prospects of detecting the reactor $\bar{\nu_e}$-Ar coherent elastic scattering with a low threshold dual-phase argon time projection chamber at Taishan

TL;DR

This paper proposes using a low-threshold dual-phase argon TPC near a reactor to detect CEνNS, enabling precise measurements of weak mixing angle and neutrino properties with high event rates.

Contribution

It introduces a novel experimental setup with a 200kg liquid argon TPC for reactor neutrino detection, emphasizing low-energy recoil detection and background suppression.

Findings

Over 11,000 events per day expected at 4 ionisation electrons threshold.

Potential to measure the weak mixing angle with high precision.

Synergy with dark matter experiments for neutrino studies.

Abstract

We propose to measure the coherent elastic neutrino nucleus scattering (CE$\nu$NS) using a dual-phase liquid argon time projection chamber (TPC) with 200kg fiducial mass. The detector is expected to be adjacent to the JUNO-TAO experiment and to be about 35m from a reactor core with 4.6GW thermal power at Taishan. The antineutrino flux is approximately 6$\times10^{12}$cm$^{-1}$s$^{-1}$ at this location, leading to more than 11,000 coherent scattering events per day in the fiducial mass. However, the nuclear recoil energies concentrate in the sub-keV region, corresponding to less than ten ionisation electrons in the liquid argon. The detection of several ionisation 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 ionisation 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 CE$\nu$NS 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 CE$\nu$NS experiment and the dark matter experiment is foreseen.