Half-life Of Double Beta Decay Research Articles

Xenon isotopes in tellurobismuthite, Boliden, Sweden

The isotopic composition of xenon is reported in four different samples of tellurobismuthite, Boliden, Sweden, of varying tellurium content. It is observed that excess 129Xe, 130Xe and 131Xe, vary proportionately to the tellurium content of the sample. From the excess 130Xe measurement, the half-life for double beta decay of 130Te is calculated to be 2·51 × 10 21 yr. From the observed excess of 128Xe in the most tellurium rich sample, the half-life for the double beta decay of 128Te is estimated to be greater than 2·7 × 10 23 yr. It is shown that solar neutrino induced reactions on 128Te and 130Te do not contribute significantly to the observed excesses of 128Xe and 130Xe. The isotopic composition of xenon in a pyrite sample from the Boliden mine and in two samples of the cesium-rich mineral, pollucite, are used to examine previous hypotheses for the origin of excess 129Xe and 131Xe in tellurium ores. It is shown that these two xenon isotopes are produced in situ by nuclear reactions on tellurium.

Te 130 -Xe 130 Age Determinations of Tellurium Minerals

The half-life for double beta decay of Te 130 is determined to be (2.83 + or - 0.30)10 21 years from an analysis of xenon and tellurium in the tellurides from Kalgoorlie, Australia. The use of high sensitivity noble gas mass spectrometry to measure small amounts of the Xe 130 formed from the double beta decay of Te 130 makes possible a new age determination method for hydrothermal deposits rich in tellurium. Three telluride samples from different geographic locations have been dated by the Te 130 -Xe 130 method and the ages obtained are consistent with the geologic age estimates.

On the probability of double beta decay

Double beta decay is discussed in relation to parity non-conservation. Two possible ways of neutrino-less double beta decay (allowed and forbidden) are investigated and the half-life of decay is calculated. For allowed transitions we obtain for Ca48 an estimatedT1/2=2×1019 years. The negative results of the experiments by Lukjanov et al., who give the valueT1/2=0.7×1019 years for the lower limit of the half-life of double beta decay of Ca48, cannot therefore be regarded as a definitive solution of the question, whether the neutrino is a Dirac or Majorana particle. Further study of double beta decay, aimed at finding higher values of the lower limit of half-life, are of considerable importance for theory.