# Performance of a prototype active veto system using liquid scintillator for a dark matter search experiment

## TL;DR

This paper evaluates a liquid scintillator-based active veto system's effectiveness in reducing background noise in a dark matter search experiment, demonstrating significant tagging efficiencies for internal and external radioisotope backgrounds.

## Contribution

It presents the performance metrics of a prototype active veto system using liquid scintillator with NaI(Tl) crystals, highlighting improvements in background tagging efficiency for dark matter detection.

## Key findings

- 48% of internal K-40 background tagged in 0-10 keV range
- 26.5% tagging efficiency for 6-20 keV events
- Up to 80% background tagging with full shielding

## Abstract

We report the performance of an active veto system using a liquid scintillator with NaI(Tl) crystals for use in a dark matter search experiment. When a NaI(Tl) crystal is immersed in the prototype detector, the detector tags 48% of the internal K-40 background in the 0-10 keV energy region. We also determined the tagging efficiency for events at 6-20 keV as 26.5 +/- 1.7% of the total events, which corresponds to 0.76 +/- 0.04 events/keV/kg/day. According to a simulation, approximately 60% of the background events from U, Th, and K radioisotopes in photomultiplier tubes are tagged at energies of 0-10 keV. Full shielding with a 40-cm-thick liquid scintillator can increase the tagging efficiency for both the internal K-40 and external background to approximately 80%.