The KamLAND Full-Volume Calibration System

TL;DR

The paper details the design, operation, and impact of a new calibration system for KamLAND that significantly reduced uncertainties in detector volume measurements, enhancing neutrino detection accuracy.

Contribution

It introduces a novel source deployment system that improves calibration precision and reduces systematic uncertainties in the KamLAND detector.

Findings

Fiducial volume uncertainty reduced by a factor of two

Calibration system successfully deployed radioactive sources throughout the detector

Enhanced accuracy in neutrino detection measurements

Abstract

We have successfully built and operated a source deployment system for the KamLAND detector. This system was used to position radioactive sources throughout the delicate 1-kton liquid scintillator volume, while meeting stringent material cleanliness, material compatibility, and safety requirements. The calibration data obtained with this device were used to fully characterize detector position and energy reconstruction biases. As a result, the uncertainty in the size of the detector fiducial volume was reduced by a factor of two. Prior to calibration with this system, the fiducial volume was the largest source of systematic uncertainty in measuring the number of anti-neutrinos detected by KamLAND. This paper describes the design, operation and performance of this unique calibration system.