Solar Influence on Nuclear Decay Rates: Constraints from the MESSENGER Mission

Abstract

We have analyzed Cs-137 decay data, obtained from a small sample onboard the MESSENGER spacecraft en route to Mercury, with the aim of setting limits on a possible correlation between nuclear decay rates and solar activity. Such a correlation has been suggested recently on the basis of data from Mn-54 decay during the solar flare of 13 December 2006, and by indications of an annual and other periodic variations in the decay rates of Si-32, Cl-36, and Ra-226. Data from five measurements of the Cs-137 count rate over a period of approximately 5.4 years have been fit to a formula which accounts for the usual exponential decrease in count rate over time, along with the addition of a theoretical solar contribution varying with MESSENGER-Sun separation. The indication of solar influence is then characterized by a non-zero value of the calculated parameter ξ, and we find ξ=(2.8+/-8.1)x10^{-3} for Cs-137. A simulation of the increased data that can hypothetically be expected following Mercury orbit insertion on 18 March 2011 suggests that the anticipated improvement in the determination of ξcould reveal a non-zero value of ξif present at a level consistent with other data.

arXiv commentAccepted for publication in Astrophysics and Space Science, 2011. 7 pages, 5 figures. Version 2 has corrected Figure 1, since Fig. 1 did not appear correctly in Version 1

References in corpus (15)

• Evidence for Correlations Between Nuclear Decay Rates and Earth-Sun Distance
• Perturbation of Nuclear Decay Rates During the Solar Flare of 13 December 2006
• Searching for modifications to the exponential radioactive decay law with the Cassini spacecraft
• Analysis of environmental influences in nuclear half-life measurements exhibiting time-dependent decay rates
• Power Spectrum Analyses of Nuclear Decay Rates
• Experimental Investigations of Changes in beta-decay rate of Co-60 and Cs-137
• Additional experimental evidence for a solar influence on nuclear decay rates
• Power Spectrum Analysis of BNL Decay-Rate Data
• Power Spectrum Analysis of Physikalisch-Technische Bundesanstalt Decay-Rate Data: Evidence for Solar Rotational Modulation
• Researches of alpha and beta radioactivity at long-term observations
• Further Evidence Suggestive of a Solar Influence on Nuclear Decay Rates
• Influence of Relic Neutrinos on Beta Radioactivity
• Periods Detected During Analysis of Radioactivity Measurements Data
• Effect of radioactivity decrease. Is there a link with solar flares?
• Evidence for Solar Influences on Nuclear Decay Rates

Cited by in corpus (4)

• Concerning the Phase of the Time-Variation in the Cl-36 Decay Rate
• Searches for solar-influenced radioactive decay anomalies using Spacecraft RTGs
• Anomalies in Radioactive Decay Rates: A Bibliography of Measurements and Theory
• Comment on "Testing claims of the GW170817 binary neutron star inspiral affecting $\beta$-decay rates''