¹³⁰Te and ¹²⁸Te double beta decay half-lives

The double beta decay half-lives of ¹³⁰Te measured in geological Te specimens of known age fall into two distinct groups: 2.5 ± 0.4 × 10²¹ yr and 8 ± 1 × 10²⁰ yr. Discussion about which value is correct has lasted for more than 30 years without a satisfactory resolution. Since the ratio of the ¹³⁰Te half-life to that of ¹²⁸Te is known (3.74 ± 0.11 × 10^-4), the ¹²⁸Xe half-life, which constrains the effective Majorana mass of the neutrino, also becomes uncertain within this factor of ∼3. Here we describe several experiments and observations, which lead us to the conclusion that the "short" half-lives are more likely to be correct. This is in agreement with preliminary results recently obtained in the direct counting NEMO-3 experiment.