Measurement of the cosmogenic activation of germanium detectors in EDELWEISS-III

TL;DR

This paper measures the rates of cosmogenic isotope production in germanium detectors used in dark matter searches, providing the most accurate data to date and comparing results with existing models and calculations.

Contribution

It presents the most precise measurements of cosmogenic activation rates in germanium detectors, enhancing understanding of background sources in dark matter experiments.

Findings

Measured production rates for isotopes: $^3$H, $^{49}$V, $^{55}$Fe, $^{65}$Zn.

Established a lower limit for $^{68}$Ge production rate.

Compared experimental results with literature models and ACTIVIA calculations.

Abstract

We present a measurement of the cosmogenic activation in the germanium cryogenic detectors of the EDELWEISS III direct dark matter search experiment. The decay rates measured in detectors with different exposures to cosmic rays above ground are converted into production rates of different isotopes. The measured production rates in units of nuclei/kg/day are 82 $\pm$ 21 for $^3$H, 2.8 $\pm$ 0.6 for $^{49}$V, 4.6 $\pm$ 0.7 for $^{55}$Fe, and 106 $\pm$ 13 for $^{65}$Zn. These results are the most accurate for these isotopes. A lower limit on the production rate of $^{68}$Ge of 74 nuclei/kg/day is also presented. They are compared to model predictions present in literature and to estimates calculated with the ACTIVIA code.