Improving radioactive contaminant identification through the analysis of delayed coincidences with an $\alpha$-spectrometer

TL;DR

This paper presents a new analysis method using delayed coincidence detection to improve identification of radioactive contaminants in ultra-pure samples, enhancing sensitivity without longer measurement times.

Contribution

The study introduces a technique leveraging time-correlation of decay sequences to better tag radioactive contaminants in alpha spectrometry.

Findings

Effective discrimination of background sources

Enhanced sensitivity in contaminant detection

Validated method on copper samples

Abstract

In the framework of rare event searches, the identification of radioactive contaminants in ultra-pure samples is a challenging task, because the signal is often at the same level of the instrumental background. This is a rather common situation for $\alpha$-spectrometers and other detectors used for low-activity measurements. In order to obtain the target sensitivity without extending the data taking live-time, analysis strategies that highlight the presence of the signal sought should be developed. In this paper, we show how to improve the contaminant tagging capability relying on the time-correlation of radioactive decay sequences. We validate the proposed technique by measuring the impurity level of both contaminated and ultra-pure copper samples, demonstrating the potential of this analysis tool in disentangling different background sources and providing an effective way to mitigate their impact in rare event searches.