On concentration of $^{42}$Ar in the Earth's atmosphere

TL;DR

This paper estimates the concentration of radioactive isotope $^{42}$Ar in Earth's atmosphere using data from a liquid argon ionization chamber experiment, providing a precise measurement of its abundance and activity.

Contribution

It presents the first direct estimate of $^{42}$Ar concentration in the atmosphere based on experimental data, improving understanding of atmospheric radioisotope levels.

Findings

$^{42}$Ar concentration is approximately 6.8 x 10^{-21} atoms per atom of $^{40}$Ar.

$^{42}$Ar activity in air is about 1.2 μBq per cubic meter.

The measurement reduces uncertainties in atmospheric radioisotope levels.

Abstract

Data from the DBA liquid argon ionization chamber experiment have been used to obtain an estimate on the concentration of $^{42}$Ar in the Earth's atmosphere, $6.8^{+1.7}_{-3.2}\cdot10^{-21}$ atoms of $^{42}$Ar per atom of $^{40}$Ar corresponding to the $^{42}$Ar activity of $1.2^{+0.3}_{-0.5}$ $\mu$Bq per cubic meter of air.