Modeling of electron emission processes accompanying Radon-$\alpha$-decays within electrostatic spectrometers

TL;DR

This paper develops a detailed model of electron emissions caused by radon alpha-decays within electrostatic spectrometers, crucial for understanding background noise in high-precision beta-spectroscopy experiments.

Contribution

It introduces a comprehensive model of electron emission processes from radon decay daughters, including energy spectra and multiplicities, validated against experimental data.

Findings

Electron energy spectra up to 400 keV modeled.

Electron multiplicities of up to 20 observed.

Model agrees well with experimental measurements.

Abstract

Electrostatic spectrometers utilized in high-resolution beta-spectroscopy studies such as in the Karlsruhe Tritium Neutrino (KATRIN) experiment have to operate with a background level of less than 10^(-2) counts per second. This limit can be exceeded by even a small number of Rn-219 or Rn-220 atoms being emanated into the volume and undergoing alpha-decay there. In this paper we present a detailed model of the underlying background-generating processes via electron emission by internal conversion, shake-off and relaxation processes in the atomic shells of the Po-215 and Po-216 daughters. The model yields electron energy spectra up to 400 keV and electron multiplicities of up to 20 which are compared to experimental data.