Identification of $^{210}$Pb and $^{210}$Po in the bulk of copper samples with a low-background alpha particle counter

TL;DR

This paper presents a highly sensitive method using a low-background alpha particle counter to measure $^{210}$Pb and $^{210}$Po contaminations in copper, enabling the first measurement of these isotopes in oxygen free copper bulk.

Contribution

The paper introduces a novel, highly sensitive assay method for detecting $^{210}$Pb and $^{210}$Po in bulk copper, achieving detection limits of a few mBq/kg.

Findings

$^{210}$Pb and $^{210}$Po contaminations in oxygen free copper were measured for the first time.

The $^{210}$Pb contamination levels ranged from 17 to 40 mBq/kg.

The residual $^{210}$Pb in oxygen free copper is linked to the electrolysis process.

Abstract

We established a method to assay $^{210}$Pb and $^{210}$Po contaminations in the bulk of copper samples using a low-background alpha particle counter. The achieved sensitivity for the $^{210}$Pb and $^{210}$Po contaminations reaches a few mBq/kg. Due to this high sensitivity, the $^{210}$Pb and $^{210}$Po contaminations in oxygen free copper bulk were identified and measured for the first time. The $^{210}$Pb contaminations of our oxygen free copper samples were 17-40 mBq/kg. Based on our investigation of copper samples in each production step, the $^{210}$Pb in oxygen free copper was understood to be a small residual of an electrolysis process. This method to measure bulk contaminations of $^{210}$Pb and $^{210}$Po could be applied to other materials.