Weak Decay of Tellurium and Barium Isotopes in Geological Samples: Current Status

Abstract

The accurate experimental determination of half-lives for 2-decay could be used to adjust parameters of the QRPA model, the strength of the particle-particle interaction g pp and to improve the calculation of Nuclear Matrix Element for 0 (neutrinoless) decay and neutrino mass m   estimations. Presently high precision direct counting experiments are difficult due to low decay rates of tellurium and barium isotopes, but their daughter nuclei accumulating in geological samples for millions of years, are clearly observable in xenon isotopes, which have extremely low background in terrestrial rocks. This work reviews current status of the previously determined half-lives of 130 Te and 128 Te and presents new estimates of half-life of 130 Ba weak decay. Our new estimates take into account the spallogenic production of 130 Xe, significantly reducing the disagreement between the only two published values of 130 Ba half-lives. Based on this result and on our early experiments we propose a new class of geological samples, which can provide an even more accurate determination of the 130 Ba half-life.

New limits on double-beta decay of $$^{190}$$Pt and $$^{198}$$Pt

“…Although allowed in the SM, the two-neutrino mode of the 2ε process (theoretically the fastest decay channel due to the biggest values of the phase space factor) has yet to be indisputably discovered. There are indications of 2ν2K decay with T 1/2 ∼ 10 21 year in 130 Ba [17][18][19] and 78 Kr [20,21]. However, the indications for 130 Ba 2ν2K decay was obtained only in geochemical experiments by detection of an anomaly in the traces of xenon isotopic concentration in barite minerals.…”

Search for Double Beta Decay of 106Cd with an Enriched 106CdWO4 Crystal Scintillator in Coincidence with CdWO4 Scintillation Counters

“…The 2ν2EC decay of 130 Ba was claimed in two geochemical experiments where anomaly in the isotopic concentrations of daughter xenon traces in old barite (BaSO 4 ) minerals was interpreted as the sought effect with the half-life T 1/2 = (2.16 ± 0.52) × 10 21 yr [15], and with T 1/2 = (6.0 ± 1.1) × 10 20 yr in [16]. In the analysis [17], the disagreement was explained by a possible cosmogenic contribution with a conclusion that the result of [15] is a more reliable one. An indication on the 2ν2EC process in 78 Kr with the half-life T 1/2 = 9.2 +5.7 −2.9 × 10 21 yr was obtained with a proportional counter with a volume of 49 lt filled by gas enriched in 78 Kr to 99.81% [18].…”

Status and Perspectives of 2ϵ, ϵβ+ and 2β+ Decays

“…However, in a following geochemical experiment, a T 1/2 = (6.0 ± 1.1) × 10 20 yr [175] was obtained in disagreement with the previous results. More recently, in Reference [198], a summary of the previous measurements was attempted while considering a more reliable value of T 1/2 = (2.2 ± 0.5) × 10 21 yr, as recommended in Reference [192] (see Table 1).…”