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

2 Pith papers cite this work. Polarity classification is still indexing.

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abstract

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: 40K and 226Ra. 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 40K and 226Ra, 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 40K 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.

years

2026 1 2024 1

verdicts

UNVERDICTED 2

representative citing papers

Weak nuclear decays deep-underground as a probe of axion dark matter

hep-ph · 2024-12-30 · unverdicted · novelty 6.0

A framework is developed to predict axion-induced time modulations in weak nuclear decays, used to derive constraints on the axion decay constant from reanalyzed Gran Sasso data on 40K and 137Cs and to propose future sensitivity to higher masses.

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Showing 2 of 2 citing papers.

  • RadioAxion results on the search for axion dark matter under Gran Sasso hep-ex · 2026-02-20 · unverdicted · none · ref 9 · internal anchor

    The RadioAxion experiment at Gran Sasso found no evidence for axion dark matter induced periodic modulations in 241Am decays and derived constraints on the axion decay constant for masses from 10^{-21} to 10^{-9} eV.

  • Weak nuclear decays deep-underground as a probe of axion dark matter hep-ph · 2024-12-30 · unverdicted · none · ref 9 · internal anchor

    A framework is developed to predict axion-induced time modulations in weak nuclear decays, used to derive constraints on the axion decay constant from reanalyzed Gran Sasso data on 40K and 137Cs and to propose future sensitivity to higher masses.