Muon detector for the COSINE-100 experiment

TL;DR

This paper describes the construction, installation, and initial performance results of a muon detector used in the COSINE-100 dark matter experiment to measure cosmic ray muons and assess their impact on dark matter signal analysis.

Contribution

It introduces a muon detector for the COSINE-100 experiment and reports its assembly, installation, and initial measurement of muon flux underground.

Findings

Muon flux measured as 328 ± 1 (stat.) ± 10 (syst.) muons/m$^2$/day

Successful assembly and deployment of the muon detector

Initial data provides baseline muon flux for background analysis

Abstract

The COSINE-100 dark matter search experiment has started taking physics data with the goal of performing an independent measurement of the annual modulation signal observed by DAMA/LIBRA. A muon detector was constructed by using plastic scintillator panels in the outermost layer of the shield surrounding the COSINE-100 detector. It is used to detect cosmic ray muons in order to understand the impact of the muon annual modulation on dark matter analysis. Assembly and initial performance test of each module have been performed at a ground laboratory. The installation of the detector in Yangyang Underground Laboratory (Y2L) was completed in the summer of 2016. Using three months of data, the muon underground flux was measured to be 328 $\pm$ 1(stat.)$\pm$ 10(syst.) muons/m$^2$/day. In this report, the assembly of the muon detector and the results from the analysis are presented.