On decay constants and orbital distance to the Sun—part I: alpha 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
  • 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
  • NPL - National Physical Laboratory
  • IAEA - International Atomic Energy Agency
  • JSI - Jozef Stefan Institute
  • LNHB - Laboratoire National Henri Becquereal
  • NRC - National Research Council of Canada - Canada

Documents & links



Claims that proximity to the Sun causes variation of decay constants at permille level have been investigated for alpha decaying nuclides. Repeated decay rate measurements of 209Po, 226Ra, 228Th, 230U, and 241Am sources were performed over periods of 200 d up to two decades at various nuclear metrology institutes around the globe. Residuals from the exponential decay curves were inspected for annual oscillations. Systematic deviations from a purely exponential decay curve differ in amplitude and phase from one data set to another and appear attributable to instabilities in the instrumentation and measurement conditions. The most stable activity measurements of α decaying sources set an upper limit between 0.0006% and 0.006% 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. Oscillations in phase with Earth’s orbital distance to the sun could not be observed within 10−5–10−6 range precision.


Original languageEnglish
Pages (from-to)1-18
Number of pages18
Issue number1
Publication statusPublished - 28 Nov 2016


  • Decay constants, Orbital distance, Sun, Alpha decay

ID: 3132098