Potential neutron-induced γ -ray background on natural tellurium relevant to Te 130 0νββ decay searches at the CUORE and SNO+ detectors
Gamma-ray production cross-section data have been obtained for the inelastic neutron scattering reactions Te126,128,130(n,n′γ) at five neutron energies between 3.6 and 10 MeV. We report data for the γ-ray energy region relevant to 0νββ decay of Te130 with a Qββ value of 2527.515 keV, assuming natural-abundance tellurium, as used at CUORE and SNO+. The natural abundance of Te130, Te128, and Te126 is 34%, 32%, and 19%, respectively. For CUORE the γ-ray cascades from the excited state in Te130 at 2527.06 keV and in Te126 at 2533.85 keV are of concern. For SNO+, accounting for its inferior energy resolution, an additional four levels are important in Te130, an additional nine levels in Te128, and an additional eight levels in Te126. Of these, we report neutron-induced γ-ray production cross sections for the strongest transitions: the 2581.15 keV level in Te130, the 2494.20, 2508.06, and 2630.14 keV levels in Te128, and the 2496.83 and 2585.46 keV level in Te126. The largest cross-section values were found for cascade γ-ray transitions to the ground state, while direct transitions to the ground state are very weak and were not observed in the present work. Both the CUORE and SNO+ detectors, however, may not be able to distinguish between cascade transitions and direct transitions to the ground state, making the neutron-induced excitation of the 2527.06 keV state of Te130 in particular a potential problem for 0νββ decay searches of Te130, because it matches its Qββ value.