# Cosmogenic Activation of Germanium Used for Tonne-Scale Rare Event Search Experiments

## TL;DR

This study uses simulations and experimental data to analyze how cosmic rays activate germanium, impacting the sensitivity of large-scale rare event detection experiments.

## Contribution

It provides a comprehensive Geant4-based simulation framework for cosmogenic activation of germanium, including comparisons with experimental data and other models.

## Key findings

- Fast neutron interactions dominate activation
- Simulations agree reasonably with experimental data
- Activation limits affect future experiment sensitivities

## Abstract

We report a comprehensive study of cosmogenic activation of germanium used for tonne-scale rare event search experiments. The germanium exposure to cosmic rays on the Earth's surface are simulated with and without a shielding container using Geant4 for a given cosmic muon, neutron, and proton energy spectrum. The production rates of various radioactive isotopes are obtained for different sources separately. We find that fast neutron induced interactions dominate the production rate of cosmogenic activation. Geant4-based simulation results are compared with the calculation of ACTIVIA and the available experimental data. A reasonable agreement between Geant4 simulations and several experimental data sets is presented. We predict that cosmogenic activation of germanium can set limits to the sensitivity of the next generation of tonne-scale experiments.