# A Study of NaI(Tl) crystal Encapsulation using Organic scintillators for the Dark Matter Search

## TL;DR

This paper explores encapsulation techniques for NaI(Tl) crystals using organic scintillators to improve detection of external radiations and surface contamination in dark matter search experiments.

## Contribution

It introduces a novel method of using active organic scintillator vetoes with NaI(Tl) crystals for better external radiation identification and stability in dark matter detectors.

## Key findings

- Effective pulse shape discrimination achieved between organic scintillator and crystal signals.
- Successful long-term stability tests of the encapsulated detector setup.
- Enhanced capability to identify external gamma radiations in dark matter experiments.

## Abstract

Scintillating NaI(Tl) crystals are used for various rare decay experiments, such as dark matter searches. The hygroscopicity of NaI(Tl) crystal makes the construction of crystal detectors in these experiments challenging and requires a tight encapsulation to prevent from air contact. More importantly, in a low radioactivity measurement, identification of external radiations and surface contamination is crucial to characterize the origin of total crystal radioactivities. Studies for NaI(Tl) crystal encapsulation with active organic scintillator vetoes have been performed to mitigate the above-mentioned issues simultaneously. A bare crystal is directly coupled with liquid and plastic scintillators to tag external radiations that penetrate from the outer part of the crystal. We report the pulse shape discrimination for organic scintillator pulses from those of the crystal scintillator in a single detector setup which makes external gammas identifiable and long-term stability tests of the detector setup.