KamLAND-PICO project to search for cosmic dark matter

TL;DR

The KamLAND-PICO project develops ultra-pure NaI(Tl) scintillators to detect WIMPs dark matter with extremely low cross sections, advancing direct detection sensitivity.

Contribution

It introduces a new ultra-pure NaI(Tl) crystal with significantly reduced U, Th, and Pb contamination for dark matter searches.

Findings

Achieved U and Th concentrations of 5.4 and 3.3 ppt.

Reached $^{210}$Pb$ contamination of 58 μBq/kg.

Developed a NaI(Tl) crystal suitable for low-background dark matter detection.

Abstract

KamLAND-PICO project aims to search for WIMPs dark matter by means of NaI(Tl) scintillator. To investigate the WIMPs candidate whose cross section is as small as $10^{-9}$ pb, a pure NaI(Tl) crystal was developed by chemical processing and taking care of surroundings. The concentration of U and Th chain was reduced to $5.4\pm0.9$ ppt and $3.3\pm2.2$ ppt, respectively. It should be remarked that the concentration of $^{210}$Pb which was difficult to reduce reached to the high purity as $58\pm26$ $\mu$Bq/kg.