A Setup for Investigating Radioactive Ion Neutralization Processes in Air

Abstract

An experimental setup and measurement technique for determining the survival time of radon daughter (²¹⁸Po) ions is described. This technique is based on the precipitation of radioactive ions on a semiconductor detector surface in an electrostatic field with the subsequent detection of α radiation from ²¹⁸Po. A dependence of the ²¹⁸Po ion neutralization probability per path unit on the absolute air humidity was obtained from the experimental results. It is revealed that a change in the air humidity from 3 to 20 g/m³ weakly influences the radon daughter transfer in the air of the measurement chamber in the absence of the electric field. The electrostatic collection efficiency is independent of the volumetric ionization rate at a radon concentration of < 3.0 × 10⁴ Bq/m³. The mean ²¹⁸Po ion survival time was found to be 2.4 and 0.9 s at a humidity of 0.8 and 14 g/m³, respectively.