SSE Talks


Evidence for a Solar Influence on Nuclear Decay Rates
June 12, 2010 at 9:15 AM MST | P. STURROCK


Peter A. Sturrock, J.B. Buncher, E. Fischbach, J.T. Gruenwald, D. Javorsek II, J.H. Jenkins, R.H. Leed, J.J. Mattes, J.R. Newport


Analyses of data acquired during two experiments at the Brookhaven National Laboratory (BNL) and one at the Physikalisch-Technische Bundesanstalt (PTB) in Germany have yielded strong evidence for an annual variation of some nuclear decay rates. Since the Sun-Earth distance varies with an annual period, it is reasonable to suspect that some kind of radiation from the Sun may be playing a role. We have found that the low-energy solar-neutrino flux exhibits a periodicity of about 12 year-1, suggesting that the solar core rotates at this (synodic) frequency, which is slower than the rotation rates of either the convection zone of the radiative zone.

If neutrinos play a role in influencing nuclear decay rates, the same periodicity may be manifested in decay measurements. We have therefore carried out power-spectrum analyses of measurements made at BNL over a 7-year interval of the decay rates of 32Si and 36Cl, and of measurements made at PTB over a 15-year interval of the decay rate of 226Ra. These analyses yield evidence for periodicities compatible with the estimated rotation rate of the solar core.

These results pose challenging questions for nuclear physics and for solar physics. Do neutrinos affect decay rates? If so, what does that tell us about neutrinos? Furthermore, if beta-decay rates vary in time, this may influence the planning of medical radiation treatments. It may also affect estimates, based on carbon dating, of the dates of early events and ancient artifacts.

The work of PAS was supported in part by the National Science Foundation through grant AST-0097128.


P.A. Sturrock (a), J.B. Buncher (b), E. Fischbach (b), J.T. Gruenwald (b), D. Javorsek II (c), J.H. Jenkins (b), R.H. Lee (d), J.J. Mattes (b), J.R. Newport (b).
a) Center for Space Science and Astrophysics, Stanford University, Stanford, CA 94305-4060, USA
b) Department of Physics, Purdue University, West Lafayette, IN 47907, USA
c) 416th Flight Test Squadron, 412th Test Wing, Edwards AFB, CA 93524, USA
d) Department of Physics, United States Air Force Academy, CO 80920, USA




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