Cosmogenic activation in double beta decay experiments

TL;DR

This paper reviews the production of long-lived radioactive isotopes by cosmic rays in materials used for double beta decay experiments, analyzing how this activation impacts detector sensitivity and ways to mitigate it.

Contribution

It provides a comprehensive review of cosmogenic activation in various detector materials and discusses methods to quantify and reduce this background for double beta decay searches.

Findings

Cosmogenic activation can produce problematic long-lived radioisotopes in detector materials.

Different calculation approaches and irradiation experiments help quantify activation yields.

Activation effects are significant for current and future double beta decay experiments.

Abstract

Double beta decay is a very rare nuclear process and, therefore, experiments intended to detect it must be operated deep underground and in ultra-low background conditions. Long-lived radioisotopes produced by the previous exposure of materials to cosmic rays on the Earth's surface or even underground can become problematic for the required sensitivity. Here, the studies developed to quantify and reduce the activation yields in detectors and materials used in the set-up of these experiments will be reviewed, considering target materials like germanium, tellurium and xenon together with other ones commonly used like copper, lead, stainless steel or argon. Calculations following very different approaches and measurements from irradiation experiments using beams or directly cosmic rays will be considered for relevant radioisotopes. The effect of cosmogenic activation in present and future double beta decay projects based on different types of detectors will be analyzed too.