Production and characterization of a $^{222}$Rn-emanating stainless steel source

TL;DR

This paper reports on a new method to produce stable radon sources by implanting radium ions into stainless steel, with comprehensive characterization confirming their potential for calibration in radiation measurements.

Contribution

It introduces a novel technique for creating radon sources through ion implantation and provides detailed characterization data demonstrating their stability and efficacy.

Findings

Radon emanation rate of about 2 Bq per sample

Successful measurement of emanation rates using multiple detection methods

Radon sources remain stable at low temperatures

Abstract

Precise radon measurements are a requirement for various applications, ranging from radiation protection over environmental studies to material screening campaigns for rare-event searches. All of them ultimately depend on the availability of calibration sources with a known and stable radon emanation rate. A new approach to produce clean and dry radon sources by implantation of $^{226}$Ra ions into stainless steel has been investigated. In a proof of principle study, two stainless steel plates have been implanted in collaboration with the ISOLDE facility located at CERN. We present results from a complete characterization of the sources. Each sample provides a radon emanation rate of about 2 Bq, which has been measured using electrostatic radon monitors as well as miniaturized proportional counters. Additional measurements using HPGe and alpha spectrometry as well as measurements of the radon emanation rate at low temperatures were carried out.