Research and Development for a Gadolinium Doped Water Cherenkov Detector

TL;DR

Introducing gadolinium into water Cherenkov detectors enhances neutron detection efficiency, enabling better identification of neutrino interactions and background reduction, which can lead to groundbreaking observations like supernova relic neutrinos.

Contribution

This paper presents the development of a dedicated Gd test facility in Kamioka Mine to demonstrate safe and effective Gd doping in water Cherenkov detectors for advanced neutrino physics.

Findings

Gd doping improves neutron detection efficiency.

The facility successfully tests Gd salt addition in water Cherenkov detectors.

Potential for new physics discoveries like supernova relic neutrinos.

Abstract

The proposed introduction of a soluble gadolinium (Gd) compound into water Cherenkov detectors can result in a high efficiency for the detection of free neutrons capturing on the Gd. The delayed 8 MeV gamma cascades produced by these captures, in coincidence with a prompt positron signal, serve to uniquely identify electron antineutrinos interacting via inverse beta decay. Such coincidence detection can reduce backgrounds, allowing a large Gd-enhanced water Cherenkov detector to make the first observation of supernova relic neutrinos and high precision measurements of Japan's reactor antineutrino flux, while still allowing for all current physics studies to be continued. Now, a dedicated Gd test facility is operating in the Kamioka Mine. This new facility houses everything needed to successfully operate a Gd doped water Cherenkov detector. Successful running of this facility will demonstrate that adding Gd salt to SK is both safe for the detector and is capable of delivering the expected physics benefits.