The measured half-life values for the transitions (Z,A)$~\rightarrow~$(Z+2,A) $+$ 2${{\mathit e}^{-}}$ $+$ 2${{\overline{\mathit \nu}}_{{e}}}$ to the 0${}^{+}$ ground state of the final nucleus are listed. We also list the transitions to an excited state of the final nucleus (0${}^{+}_{i}$, etc.). We report only the measuremetnts with the smallest (or comparable) uncertainty for each transition.

${\mathrm {\mathit t_{1/2}}}$ ($ 10^{21} $ yr) ISOTOPE TRANSITION METHOD DOCUMENT ID • • We do not use the following data for averages, fits, limits, etc. • • $ 0.771 {}^{+0.008}_{-0.006} {}^{+0.012}_{-0.015} $ ${}^{130}\mathrm {Te}$ CUORE 1 ADAMS 2021 $ 0.00712 {}^{+0.00018}_{-0.00014} \pm0.00010 $ ${}^{100}\mathrm {Mo}$ CUPID-Mo 2 ARMENGAUD 2020 $ 18 \pm5 \pm1 $ ${}^{124}\mathrm {Xe}$ 2${{\mathit \nu}}$ DEC XENON1T 3 APRILE 2019 E $ 0.0068 \pm0.00001 {}^{+0.00038}_{-0.00040} $ ${}^{100}\mathrm {Mo}$ NEMO-3 4 ARNOLD 2019 $ 0.0860 \pm0.0003 {}^{+0.0019}_{-0.0013} $ ${}^{82}\mathrm {Se}$ CUPID-0 5 AZZOLINI 2019 B $ 0.0939 \pm0.0017 \pm0.0058 $ ${}^{82}\mathrm {Se}$ NEMO-3 6 ARNOLD 2018 $ 0.0263 {}^{+0.0011}_{-0.0012} $ ${}^{116}\mathrm {Cd}$ AURORA 7 BARABASH 2018 $ \text{> 0.87} $ ${}^{134}\mathrm {Xe}$ EXO-200 8 ALBERT 2017 C $ 0.82 \pm0.02 \pm0.06 $ ${}^{130}\mathrm {Te}$ CUORE-0 9 ALDUINO 2017 $ 0.00690 \pm0.00015 \pm0.00037 $ ${}^{100}\mathrm {Mo}$ CUPID 10 ARMENGAUD 2017 $ 0.0274 \pm0.0004 \pm0.0018 $ ${}^{116}\mathrm {Cd}$ NEMO-3 11 ARNOLD 2017 $ 0.064 {}^{+0.007}_{-0.006} {}^{+0.012}_{-0.009} $ ${}^{48}\mathrm {Ca}$ NEMO-3 12 ARNOLD 2016 $ 0.00934 \pm0.00022 {}^{+0.00062}_{-0.00060} $ ${}^{150}\mathrm {Nd}$ NEMO-3 13 ARNOLD 2016 A $ 1.926 \pm0.094 $ ${}^{76}\mathrm {Ge}$ GERDA 14 AGOSTINI 2015 A $ 0.00693 \pm0.00004 $ ${}^{100}\mathrm {Mo}$ NEMO-3 15 ARNOLD 2015 $ 2.165 \pm0.016 \pm0.059 $ ${}^{136}\mathrm {Xe}$ EXO-200 16 ALBERT 2014 $ 9.2 {}^{+5.5}_{-2.6} \pm1.3 $ ${}^{78}\mathrm {Kr}$ BAKSAN 17 GAVRILYAK 2013 $ 2.38 \pm0.02 \pm0.14 $ ${}^{136}\mathrm {Xe}$ KamLAND-Zen 18 GANDO 2012 A $ 0.7 \pm0.09 \pm0.11 $ ${}^{130}\mathrm {Te}$ NEMO-3 19 ARNOLD 2011 $ 0.0235 \pm0.0014 \pm0.0016 $ ${}^{96}\mathrm {Zr}$ NEMO-3 20 ARGYRIADES 2010 $ 0.69 {}^{+0.10}_{-0.08} \pm0.07 $ ${}^{100}\mathrm {Mo}$ $0{}^{+} \rightarrow 0{}^{+}_{1}$ ${}^{}\mathrm {Ge}$ coinc. 21 BELLI 2010 $ 0.57 {}^{+0.13}_{-0.09} \pm0.08 $ ${}^{100}\mathrm {Mo}$ $0{}^{+} \rightarrow 0{}^{+}_{1}$ NEMO-3 22 ARNOLD 2007 $ 0.096 \pm0.003 \pm0.010 $ ${}^{82}\mathrm {Se}$ NEMO-3 23 ARNOLD 2005 A $ 0.029 {}^{+0.004}_{-0.003} $ ${}^{116}\mathrm {Cd}$ ${}^{}\mathrm {Cd}WO_{4}$ scint. 24 DANEVICH 2003 1  ADAMS 2021 use 102.7 kg yr of ${}^{130}\mathrm {Te}$ exposure, collected by the CUORE bolometric detector at LNGS, to perform the most precise measurement of 2${{\mathit \nu}}$ ${{\mathit \beta}}{{\mathit \beta}}$ decay of this nuclide to date. The dataset is more than 10-times that used by the CUORE-0 experiment. Supersedes ALDUINO 2017 . 2  ARMENGAUD 2020 use the Li$_{2}{}^{100}\mathrm {Mo}O_{4}$ scintillating bolometers to determine the half-life of the 2${{\mathit \nu}}$ ${{\mathit \beta}}{{\mathit \beta}}$ decay of ${}^{100}\mathrm {Mo}$. The total exposure was 42.235 kg$\cdot{}$d. The single-state dominance for this decay is favored at $>$ 3 $\sigma $. 3  APRILE 2019E report first measurement of two-neutrino double electron capture in ${}^{124}\mathrm {Xe}$ using the XENON1T detector with a 0.73 t-yr exposure. An excess of $126$ $\pm29$ events is observed at $64.3$ $\pm0.6$ keV decay energy, corresponding to $\sqrt {\Delta {{\mathit \chi}^{2}} }$ = 4.4 with respect to the background-only hypothesis. 4  ARNOLD 2019 use the NEMO-3 tracking calorimeter with 34.3 kg y exposure to determine the 2${{\mathit \nu}}$ ${{\mathit \beta}}{{\mathit \beta}}$ half-life of ${}^{100}\mathrm {Mo}$. Supersedes ARNOLD 2015 . 5  AZZOLINI 2019B use the CUPID-0 experiment, utilizing ZnSe bolometers and an exposure of 9.95 kg$\cdot{}$yr of ${}^{}\mathrm {Zn}{}^{82}\mathrm {Se}$, to determine the half-life of the 2${{\mathit \nu}}$ ${{\mathit \beta}}{{\mathit \beta}}$ decay of ${}^{82}\mathrm {Se}$. The analysis provides evidence for single state dominance showing that the higher state dominance is disfavored at the level of 5.5 ${{\mathit \sigma}}$ . 6  ARNOLD 2018 use the NEMO-3 tracking detector to determine the 2 ${{\mathit \nu}}{{\mathit \beta}}{{\mathit \beta}}$ half-life of ${}^{82}\mathrm {Se}$. 0.93 kg of ${}^{82}\mathrm {Se}$ was observed for 5.25 y. The half-life value was obtained based on the single-state-dominance (SSD) hypothesis, preferred in this case by about 2 $\sigma $. Supersedes ARNOLD 2005A. 7  BARABASH 2018 use 1.162 kg of ${}^{116}\mathrm {Cd}WO_{4}$ scintillating crystals to obtain this value. Supersedes DANEVICH 2003 with analogous source and agrees with ARNOLD 2017 with the NEMO-3 detector. 8  ALBERT 2017C uses the EXO-200 detector that contains $19.098$ $\pm0.014\%$ admixture of ${}^{134}\mathrm {Xe}$ to search for the 2${{\mathit \nu}}$ ${{\mathit \beta}}{{\mathit \beta}}$ decay mode. The exposure is 29.6 kg$\cdot{}$year. The median sensitivity is $1.2 \times 10^{21}$ years. 9  ALDUINO 2017 use the CUORE-0 detector containing 10.8 kg of ${}^{130}\mathrm {Te}$ in 52 crystals of TeO$_{2}$. The exposure was 9.3 kg yr of ${}^{130}\mathrm {Te}$. This is a more accurate rate determination than in ARNOLD 2011 and BARABASH 2011A. 10  ARMENGAUD 2017 use $185.9$ $\pm0.1$ g crystal of Li$_{2}{}^{100}\mathrm {Mo}{}^{}\mathrm {O}_{4}$ to determine the ${}^{100}\mathrm {Mo}$ 2${{\mathit \nu}}$ ${{\mathit \beta}}{{\mathit \beta}}$ half-life. The exposure was of $1303$ $\pm26$ hours only, using novel technique. 11  ARNOLD 2017 use the NEMO-3 tracking calorimeter, containing 410 grams of enriched ${}^{116}\mathrm {Cd}$ exposed for 5.26 years, to determine the half-life value. 12  ARNOLD 2016 use the NEMO-3 detector and a source of 6.99 g of ${}^{48}\mathrm {Ca}$. The half-life is based on 36.7 g year exposure. It is consistent, although somewhat longer, than the previous determinations of the half-life. Supersedes BARABASH 2011A. 13  ARNOLD 2016A use the NEMO-3 tracking calorimeter, containing 36.6 g of ${}^{150}\mathrm {Nd}$ exposed for 1918.5 days, to determine the half-life. Supersedes ARGYRIADES 2009 . 14  AGOSTINI 2015A use 17.9 kg yr exposure of the GERDA calorimeter to derive an improved measurement of the 2${{\mathit \nu}}{{\mathit \beta}}{{\mathit \beta}}$ decay half life of ${}^{76}\mathrm {Ge}$. 15  ARNOLD 2015 use the NEMO-3 tracking calorimeter with 34.3 kg yr exposure to determine the 2${{\mathit \nu}}{{\mathit \beta}}{{\mathit \beta}}$ -half life of ${}^{100}\mathrm {Mo}$. Supersedes ARNOLD 2005A and ARNOLD 2004 . 16  ALBERT 2014 use the EXO-200 tracking detector for a re-measurement of the 2${{\mathit \nu}}{{\mathit \beta}}{{\mathit \beta}}$ -half life of ${}^{136}\mathrm {Xe}$. A nuclear matrix element of $0.0218$ $\pm0.0003$ MeV${}^{-1}$ is derived from this data. Supersedes ACKERMAN 2011 . 17  GAVRILYAK 2013 use a proportional counter filled with ${}^{}\mathrm {Kr}$ gas to search for the 2${{\mathit \nu}}$ 2K decay of ${}^{78}\mathrm {Kr}$. Data with the enriched and depleted ${}^{}\mathrm {Kr}$ were used to determine signal and background. A 2.5${{\mathit \sigma}}$ excess of events obtained with the enriched sample is interpreted as an indication for the presence of this decay. 18  GANDO 2012A use a modification of the existing KamLAND detector. The ${{\mathit \beta}}{{\mathit \beta}}$ decay source/detector is 13 tons of enriched ${}^{136}\mathrm {Xe}$-loaded scintillator contained in an inner balloon. The 2${{\mathit \nu}}{{\mathit \beta}}{{\mathit \beta}}$ decay rate is derived from the fit to the spectrum between 0.5 and 4.8 MeV. This result is in agreement with ACKERMAN 2011 . 19  ARNOLD 2011 use enriched ${}^{130}\mathrm {Te}$ in the NEMO-3 detector to measure the 2 ${{\mathit \nu}}$ decay rate. This result is in agreement with, but more accurate than ARNABOLDI 2003 . 20  ARGYRIADES 2010 use $9.4$ $\pm0.2$ g of ${}^{96}\mathrm {Zr}$ in NEMO-3 detector and identify its 2${{\mathit \nu}}{{\mathit \beta}}{{\mathit \beta}}$ decay. The result is in agreement and supersedes ARNOLD 1999 . 21  BELLI 2010 use enriched ${}^{100}\mathrm {Mo}$ with 4 HP ${}^{}\mathrm {Ge}$ detectors to record the 590.8 and 539.5 keV ${{\mathit \gamma}}$ rays from the decay of the 0${}^{+}_{1}$ state in ${}^{100}\mathrm {Ru}$ both in singles and coincidences. This result confirms the measurement of KIDD 2009 and ARNOLD 2007 and supersedes them. 22  First exclusive measurement of 2${{\mathit \nu}}$ -decay to the first excited 0${}^{+}_{1}$-state of daughter nucleus. ARNOLD 2007 use the NEMO-3 tracking calorimeter to detect all particles emitted in decay. Result agrees with the inclusive ( 0 ${{\mathit \nu}}{+}$ 2 ${{\mathit \nu}}$ ) measurement of DEBRAECKELEER 2001 . 23  ARNOLD 2005A use the NEMO-3 tracking detector to determine the 2 ${{\mathit \nu}}{{\mathit \beta}}{{\mathit \beta}}$ half-life of ${}^{82}\mathrm {Se}$ with high statistics and low background (389 days of data taking). Supersedes ARNOLD 2004 . 24  DANEVICH 2003 is calorimetric measurement of 2${{\mathit \nu}}{{\mathit \beta}}{{\mathit \beta}}$ ground state decay of ${}^{116}\mathrm {Cd}$ using enrichedCdWO$_{4}$ scintillators. Agrees with EJIRI 1995 and ARNOLD 1996 . Supersedes DANEVICH 2000 .

References:

ADAMS 2021 PRL 126 171801 Measurement of the $2\nu\beta\beta$ Decay Half-Life of $^{130}\mathrm{Te}$ with CUORE ARMENGAUD 2020 EPJ C80 674 Precise measurement of $2\nu \beta \beta $ decay of $^{100}$Mo with the CUPID-Mo detection technology APRILE 2019E NAT 568 532 Observation of two-neutrino double electron capture in $^{124}$Xe with XENON1T ARNOLD 2019 EPJ C79 440 Detailed studies of $^{100}$Mo two-neutrino double beta decay in NEMO-3 AZZOLINI 2019B PRL 123 262501 ARNOLD 2018 EPJ C78 821 Final results on ${}^\mathbf 82 \hbox {Se}$ double beta decay to the ground state of ${}^\mathbf 82 \hbox {Kr}$ from the NEMO-3 experiment BARABASH 2018 PR D98 092007 Final results of the Aurora experiment to study $2\beta$ decay of $^{116}\mathrm{Cd}$ with enriched $^{116}\mathrm{Cd}{\mathrm{WO}}_{4}$ crystal scintillators ALBERT 2017C PR D96 092001 Searches for Double Beta Decay of ${}^{134}\mathrm {Xe}$ with EXO-200 ALDUINO 2017 EPJ C77 13 Measurement of the Two-Neutrino Double-Beta Decay Half-Life of ${}^{130}\mathrm {Te}$ with the CUORE-0 Experiment ARMENGAUD 2017 EPJ C77 785 Development of ${}^{100}\mathrm {Mo}$-containing Scintillating Bolometers for a High-sensitivity Neutrinoless Double-beta Decay Search ARNOLD 2017 PR D95 012007 Measurement of the 2${{\mathit \nu}}{{\mathit \beta}}{{\mathit \beta}}$ Decay Half-Life and Search for the 0${{\mathit \nu}}$ $\beta \beta $ Decay of ${}^{116}\mathrm {Cd}$ with the NEMO-3 Detector ARNOLD 2016A PR D94 072003 Measurement of the 2${{\mathit \nu}}{{\mathit \beta}}{{\mathit \beta}}$ Decay Half-Life of ${}^{150}\mathrm {Nd}$ and a Search for 0${{\mathit \nu}}{{\mathit \beta}}{{\mathit \beta}}$ Decay Processes with the Full Exposure from the NEMO-3 Detector ARNOLD 2016 PR D93 112008 Measurement of the Double-Beta Decay Half-Life and Search for the Neutrinoless Double-Beta Decay of ${}^{48}\mathrm {Ca}$ with the NEMO-3 Detector AGOSTINI 2015A EPJ C75 416 Results on ${{\mathit \beta}}{{\mathit \beta}}$ Decay with Emission of Two Neutrinos or Majorons in ${}^{76}\mathrm {Ge}$ from GERDA Phase I ARNOLD 2015 PR D92 072011 Results of the Search for Neutrinoless Double-${{\mathit \beta}}$ Decay in ${}^{100}\mathrm {Mo}$ with the NEMO-3 Experiment ALBERT 2014 PR C89 015502 An Improved Measurement of the 2${{\mathit \nu}}{{\mathit \beta}}{{\mathit \beta}}$ Half-life of ${}^{136}\mathrm {Xe}$ with EXO-200 GAVRILYAK 2013 PR C87 035501 Indications of 2${{\mathit \nu}}$ 2${{\mathit K}}$ Capture in ${}^{78}\mathrm {Kr}$ GANDO 2012A PR C85 045504 Measurement of the Double-${{\mathit \beta}}$ Decay Half-Life of ${}^{136}\mathrm {Xe}$ with the KamLAND-Zen Experiment ARNOLD 2011 PRL 107 062504 Measurement of the ${{\mathit \beta}}{{\mathit \beta}}$ Decay Half-Life of ${}^{130}\mathrm {Te}$ with the NEMO-3 Detector ARGYRIADES 2010 NP A847 168 Measurement of the Two Neutrino Double $\beta $ Decay Half-Life of ${}^{96}\mathrm {Zr}$ with the NEMO-3 Detector BELLI 2010 NP A846 143 New Observation of 2${{\mathit \beta}}$ 2${{\mathit \nu}}$ Decay of ${}^{100}\mathrm {Mo}$ to the 0${}^{+}_{1}$ Level of ${}^{100}\mathrm {Ru}$ in the ARMONIA Experiment ARNOLD 2007 NP A781 209 Measurement of Double beta Decay of ${}^{100}\mathrm {Mo}$ to Excited States in the NEMO-3 Experiment ARNOLD 2005A PRL 95 182302 First Results of the Search for Neutrinoless Double-Beta Decay with the NEMO 3 Detector DANEVICH 2003 PR C68 035501 Search for 2$\beta $ Decay of Cadmium and Tungsten Isotopes: Final Results of the Solotvina Experiment