Search for time modulations in the decay rate of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"><mml:mrow><mml:msup><mml:mrow /><mml:mrow><mml:mn>40</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>K and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si13.gif" overflow="scroll"><mml:mrow><mml:msup><mml:mrow /><mml:mrow><mml:mn>232</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>Th

Bellotti, E.; Broggini, C.; Carlo, G. Di; Laubenstein, M.; Menegazzo, R.; Pietroni, Massimo

doi:10.1016/j.astropartphys.2014.05.006

Cited by 16 publications

(20 citation statements)

References 30 publications

(36 reference statements)

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“…This way salt and paraffine melt together and, after cooling, a solid and compact block was formed. As a consequence it was possible to avoid the slow and long process of settlement of the salt powder (about 6 months) which was measured in [7], where KHCO 3 was used alone, and which was causing a time dependent detection efficiency. Finally, the whole set-up is shielded by at least 10 cm of lead ( Fig.…”

Section: The 40 K Experimentsmentioning

confidence: 99%

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Search for time modulations in the decay constant of 40K and 226Ra at the underground Gran Sasso Laboratory

et al. 2018

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Time modulations at per mil level have been reported to take place in the decay constant of several nuclei with period of one year (most cases) but also of about one month or one day. On the other hand, experiments with similar or better sensitivity have been unable to detect any modulation. In this letter we give the results of the activity study of two different sources: 40 K and 226 Ra. The two gamma spectrometry experiments have been performed underground at the Gran Sasso Laboratory, this way suppressing the time dependent cosmic ray background. Briefly, our measurements reached the sensitivity of 3.4 and 3.5 parts over 10 6 for 40 K and 226 Ra, respectively (1 sigma) and they do not show any statistically significant evidence of time dependence in the decay constant. We also give the results of the activity measurement at the time of the two strong X-class solar flares which took place in September 2017. Our data do not show any unexpected time dependence in the decay rate of 40 K in correspondence with the two flares. To the best of our knowledge, these are the most precise and accurate results on the stability of the decay constant as function of time.

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Section: The 40 K Experimentsmentioning

confidence: 99%

“…In the past we also performed a few gamma spectroscopy experiments in the underground Gran Sasso Laboratory, excluding modulations with amplitude larger than a few parts over 10 5 in 137 Cs [12], 222 Rn [13] and 232 Th [7].…”

Section: Introductionmentioning

confidence: 99%

Search for time modulations in the decay constant of 40K and 226Ra at the underground Gran Sasso Laboratory

et al. 2018

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“…Evidence has been collected to demonstrate instabilities in the decay of other radionuclides [10,11] and by means of time-frequency analysis periodicity at shorter and longer term than 1 year have been claimed [11–13]. However, this interpretation is being challenged by the publication of data sets confirming a close adherence to exponential decay with residuals in the 10 −5 range [16,18,20,21,23]. …”

Section: Introductionmentioning

confidence: 99%

Evidence against solar influence on nuclear decay constants

et al. 2016

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The hypothesis that proximity to the Sun causes variation of decay constants at permille level has been tested and disproved. Repeated activity measurements of mono-radionuclide sources were performed over periods from 200 days up to four decades at 14 laboratories across the globe. Residuals from the exponential nuclear decay curves were inspected for annual oscillations. Systematic deviations from a purely exponential decay curve differ from one data set to another and are attributable to instabilities in the instrumentation and measurement conditions. The most stable activity measurements of alpha, beta-minus, electron capture, and beta-plus decaying sources set an upper limit of 0.0006% to 0.008% to the amplitude of annual oscillations in the decay rate. Oscillations in phase with Earth’s orbital distance to the Sun could not be observed within a 10−6 to 10−5 range of precision. There are also no apparent modulations over periods of weeks or months. Consequently, there is no indication of a natural impediment against sub-permille accuracy in half-life determinations, renormalisation of activity to a distant reference date, application of nuclear dating for archaeology, geo- and cosmochronology, nor in establishing the SI unit becquerel and seeking international equivalence of activity standards.

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“…For 232 Th (α), (Bellotti et al, 2015) noticed a periodicity of 300 days, but attributed this to instabilities in the measurement equipment. Those same authors found strong annual periodicity in 40 K (EC).…”

Section: Contrary Evidencementioning

confidence: 99%

“…A common empirical finding is that the variability in decay rates is correlated with the seasonal variability in distance to the Sun, or less occasionally with other variables such as cosmic ray flux. There is ample empirical evidence for this, as follows: 32 Si (β-) (Jenkins et al, 2009), 36 Cl (β-, EC+ β+) (Jenkins et al, 2012), 40 K (EC), (Bellotti et al, 2015) found a strong annual periodicity compatible with changes in the cosmic ray flux, 60 Co (β-) (Parkhomov, 2011), 85 Kr (β-) (Sturrock et al, 2014), 90 Sr (β-) (Parkhomov, 2011) (Sturrock et al, 2014), 90 Y (β-) (Parkhomov, 2011), 108 Ag (Sturrock et al, 2014), 226 Ra (α, β-) (Sturrock et al, 2014), 133 Ba (EC) (Parkhomov, 2011) (Sturrock et al, 2014): this nuclide showed a strong annual effect but also much greater variability than others,…”

Section: Empirical Evidence For Variable Decay Ratesmentioning

confidence: 99%

Hidden Variable Theory Supports Variability in Decay Rates of Nuclides

Pons

Pons²

2015

APR

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PROBLEM-The orthodox expectation is for decay rates to be strictly constant for all types of decay (β+, β-, EC, α). However empirical results show strong evidence for nuclides having variable decay rates, typically evident as periodicity. The volume of data available suggests this is a real phenomenon, not merely a spurious outcome of measurement errors. However the problem is complex because the data are conflicted for different decays. Consequently it is a significant challenge to explain how the variability might arise, what factors could be involved, and how the underlying mechanisms of causality might operate. PURPOSE-This paper develops a theoretical explanation of the variability of nuclide decay rates. APPROACH-The non-local hidden-variable solution provided by the Cordus theory was used, specifically its mechanics for neutrino-species interactions with nucleons. FINDINGS-It is predicted that the β-, β+ and electron capture processes are induced by pre-supply of neutrino-species, and that the effects are asymmetrical for those species. Also predicted is that different input energies are required, i.e. that a threshold effect exists. Four simple non-contentious lemmas are proposed with which it is straightforward to explain why β-and EC would be enhanced and correlate to solar neutrino flux (proximity & activity), and α emission unaffected. It is shown that the concept of a neutrino-species asymmetry makes sense of the broad patterns evident in the empirical data. IMPLICATIONS-The results support the variability of decay rates, on theoretical grounds. The type of decay (β+, β-, EC, α) is found to be a key variable in this theory, as is the type of neutrino species and its energy. ORIGINALITY-The novel contribution is the provision of a theoretical explanation for why decay rates would be variable. A detailed mechanism is presented for neutrino-species induced decay. Also novel is the prediction that the interaction is asymmetrical, and that the energy requirements are different for the various types of decay.

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Search for time modulations in the decay rate of 40K and 232Th

Cited by 16 publications

References 30 publications

Search for time modulations in the decay constant of 40K and 226Ra at the underground Gran Sasso Laboratory

Search for time modulations in the decay constant of 40K and 226Ra at the underground Gran Sasso Laboratory

Evidence against solar influence on nuclear decay constants

Hidden Variable Theory Supports Variability in Decay Rates of Nuclides

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