On decay constants and orbital distance to the Sun—part III: beta plus and electron capture decay

Research output: Contribution to journalArticlepeer-review


  • Stefaan Pommé
  • H Stroh
  • J Paepen
  • Raf Van Ammel
  • H Marouli
  • T Altzitzoglou
  • M Hult
  • K Kossert
  • O Nähle
  • H Schrader
  • F Juget
  • C Bailat
  • Y Nedjadi
  • F Bochud
  • T Buchillier
  • C Michotte
  • S Courte
  • M W van Rooy
  • M J van Staden
  • J Lubbe
  • B 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
  • J D Keightley
  • K M Ferreira
  • S M Collins
  • A Ceccatelli
  • Branko Vodenik
  • M Korun
  • V Chisté
  • M N Amiot

Institutes & Expert groups

  • EC - JRC - European Commission - Joint Research Centre
  • JSI - Jozef Stefan Institute
  • 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
  • LNHB - Laboratoire National Henri Becquereal

Documents & links


The hypothesis that seasonal changes in proximity to the Sun cause variation of decay constants at permille level has been tested for radionuclides disintegrating through electron capture and beta plus decay. Activity measurements of 22Na, 54Mn, 55Fe, 57Co, 65Zn, 82+85Sr, 90Sr, 109Cd, 124Sb, 133Ba, 152Eu, and 207Bi sources were repeated over periods from 200 d up to more than 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 appear attributable to instabilities in the instrumentation and measurement conditions. Oscillations in phase with Earth’s orbital distance to the sun could not be observed within 10−4–10−5 range precision. The most stable activity measurements of β+ and EC decaying sources set an upper limit of 0.006% or less to the amplitude of annual oscillations in the decay rate. There are no apparent indications for systematic oscillations at a level of weeks or months.


Original languageEnglish
Pages (from-to)36-50
Number of pages14
Publication statusPublished - 28 Nov 2016


  • half-life, decay constant, non-exponential decay, adioactivity, Sun, neutrino

ID: 3132099