Neutron detection in the SNO+ water phase

TL;DR

SNO+ is a neutrino detector that, during its water phase, effectively detects neutrons with a capture time of about 208 microseconds and at least 46% efficiency, demonstrating its capabilities for neutron detection.

Contribution

This paper reports the first measurement of neutron capture time and detection efficiency in the SNO+ water Cherenkov phase, highlighting its neutron detection performance.

Findings

Neutron capture time of 208.2 microseconds with 2.1 microseconds uncertainty.

Neutron detection efficiency lower bound of 46%.

Effective neutron detection demonstrated in a large underground water Cherenkov detector.

Abstract

SNO+ is a multipurpose neutrino experiment located approximately 2 km underground in SNOLAB, Sudbury, Canada. The detector started taking physics data in May 2017 and is currently completing its first phase, as a pure water Cherenkov detector. The low trigger threshold of the SNO+ detector allows for a substantial neutron detection efficiency, as observed with a deployed ^{241}Am^{9}Be source. Using a statistical analysis of one hour AmBe calibration data, we report a neutron capture constant of 208.2 + 2.1(stat.) us and a lower bound of the neutron detection efficiency of 46% at the center of the detector.