Capability of detecting low energy events in JUNO Central Detector

TL;DR

This paper proposes a new trigger scheme for the JUNO detector that significantly lowers the energy detection threshold, enhancing sensitivity to solar and supernova neutrinos by reducing background noise.

Contribution

A novel trigger scheme is developed and simulated, enabling the JUNO detector to detect lower energy events down to 0.1 MeV with controlled $^{14}$C levels.

Findings

Trigger threshold can be reduced to 0.2 MeV with current methods.

Further reduction to 0.1 MeV is possible with better $^{14}$C control.

The new scheme improves detection capabilities for low energy neutrinos.

Abstract

The Jiangmen Underground Neutrino Observatory (JUNO) is an experimental project designed to determine the neutrino mass ordering and probe the fundamental properties of the neutrino oscillations. The JUNO central detector is a spherical liquid scintillator detector with a diameter of 35.4 m and equipped with approximately 18,000 20-inch PMTs. A trigger threshold of 0.5 MeV can be easily achieved by using a common multiplicity trigger and can meet the requirements for measuring neutrino mass ordering. However, it is essential to further reduce the trigger threshold for detecting solar neutrinos and supernova neutrinos. A sophisticated trigger scheme is proposed to achieve a low energy threshold by reducing the level of low energy radioactivity and dark noise coincidence. With the new trigger scheme, the events rate of the central detector from different types of sources have been carefully studied by using a detailed detector simulation. It shows that the trigger threshold can be reduced to 0.2 MeV, or even 0.1 MeV, if the concentration of $^{14}$C in liquid scintillator can be well controlled.