2011/07/31 by Ephraim Fischbach, Ke-Jung Chen, K. Joseph Chen +13
Decision Sciences · Health Professions · Physics and Astronomy · #Astronomy #Astrophysics #Exponential decay #Nuclear physics #Physics #Radioactive Decay and Measurement Techniques #Radioactivity and Radon Measurements #Scientific Measurement and Uncertainty Evaluation #Solar cycle #Solar flare #Solar maximum #Solar wind #Spacecraft #astro-ph.SR #nucl-ex
paper · pdf · doi:10.1007/s10509-011-0808-5
published as Astrophysics and Space Science, 2012. 337(1): p. 39-45 · Accepted 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
arxiv created 2011/09/01 · openalex publication_date 2011/09/08 · arxiv updated 2012/01/20 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
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.