Cosmogenic activation of a natural tellurium target

TL;DR

This study investigates cosmogenic activation of natural tellurium, identifying potential background isotopes for neutrinoless double beta decay experiments and calculating their production rates using various models.

Contribution

It provides detailed calculations of cosmogenic isotope production in tellurium for the first time, aiding background estimation in double beta decay experiments.

Findings

Identified 18 isotopes as potential backgrounds with Q-value > 2 MeV.

Calculated production rates using ACTIVIA, TENDL, and flux models, showing good agreement with experimental data.

Applied results to SNO+ experiment scenarios, including underground cooling and surface purification.

Abstract

130Te is one of the candidates for the search for neutrinoless double beta decay. It is currently planned to be used in two experiments: CUORE and SNO+. In the CUORE experiment TeO2 crystals cooled at cryogenic temperatures will be used. In the SNO+ experiment natTe will be deployed up to 0.3% loading in the liquid scintillator volume. A possible background for the signal searched for, are the high Q-value, long-lived isotopes, produced by cosmogenic neutron and proton spallation reaction on the target material. A total of 18 isotopes with Q-value larger than 2 MeV and T1/2 >20 days have been identified as potential backgrounds. In addition low Q-value, high rate isotopes can be problematic due to pile-up effects, specially in liquid scintillator based detectors. Production rates have been calculated using the ACTIVIA program, the TENDL library, and the cosmogenic neutron and proton flux parametrization at sea level from Armstrong and Gehrels for both long and short lived isotopes. The obtained values for the cross sections are compared with the existing experimental data and calculations. Good agreement has been generally found. The results have been applied to the SNO+ experiment for one year of exposure at sea level. Two possible cases have been considered: a two years of cooling down period deep underground, or a first purification on surface and 6 months of cooling down deep underground. Deep underground activation at the SNOLAB location has been considered.