Evidence against solar influence on nuclear decay constants

Research output: Contribution to journalArticlepeer-review


  • Stefaan Pommé
  • Heike Stroh
  • Jan Paepen
  • Raf Van Ammel
  • Maria Marouli
  • Timotheos Altzitzoglou
  • Mikael Hult
  • Karsten Kossert
  • Ole Nähle
  • Heinrich Schrader
  • Frederic Juget
  • Claude J. Bailat
  • Youcef Nedjadi
  • François Bochud
  • Thierry Buchillier
  • S Courte
  • M W van Rooy
  • M J van Staden
  • J Lubbe
  • Bruce R.S. Simpson
  • A Fazio
  • P De Felice
  • T W Jackson
  • W M Van Wyngaardt
  • M I Reinhard
  • J Golya
  • S. Bourke
  • T Roy
  • R Galea
  • John D. Keightley
  • Kelley M. Ferreira
  • S M Collins
  • Alessia Ceccatelli
  • Michael P. Unterweger
  • Ryan P. Fitzgerald
  • Dennis E. Bergeron
  • Leticia S, Pibida
  • Branko Vodenik
  • M. Korun
  • V Chisté
  • Marie-Noëlle Amiot

Institutes & Expert groups

  • EC - JRC - European Commission - Joint Research Centre
  • NIST - National Institute of Standards and Technology
  • PTB - Physikalisch-Technische Bundesanstalt
  • IRA - Institute of Radiation Physics, University Hospital of Lausanne
  • BIPM - Bureau International des Poids et Mesures
  • NMISA - Radioactivity Standards laboratory - South Africa
  • ENEA - Italian National Agency for New Technologies
  • ANSTO - Australian Nuclear Science and Technology Organisation
  • NRC - National Research Council of Canada - Canada
  • NPL - National Physical Laboratory
  • IAEA - International Atomic Energy Agency
  • JSI - Jozef Stefan Institute
  • LNHB - Laboratoire National Henri Becquereal

Documents & links


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 to 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.


Original languageEnglish
Pages (from-to)281-286
Number of pages6
JournalPhysics Letters B
Publication statusPublished - 10 Oct 2016


  • Half-life, Decay constant, Uncertainty, Radioactivity, Sun, Neutrino

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