[ RadSafe ] variability of decay constants

George Stanford gstanford at aya.yale.edu
Sun Jul 26 14:24:50 CDT 2009


      Thanks -- interesting.

      Paper #1 seems ill-founded.  Since seasonal 
temperatures have a phase delay of about a month, 
it only take a glance at the charts in that paper 
to see that the correlation with seasonal 
temperature would be much better than with earth-sun distance.

      Paper #2 shows how the temperature changes 
can affect the measurements and account for the 
observations  Small seasonal changes in the 
temperature in the laboratory can cause changes in:
-  argon density in an ionization chamber, affecting counter sensitivity;
-  air density between radioactive source and 
detector, affecting beta-ray transmission.

      When you're trying to measure effects as 
small as +/- 0.15%, you've got to be pretty darn 
careful with your experimental conditions.

      It looks as though decay probabilities remain immutable.

      -- George


At 02:20 PM 7/25/2009, Peter Bossew wrote:
For those interested in more fundamental questions: 2 articles on the
alleged temporal variability of decay constants.

Evidence for Correlations Between Nuclear Decay Rates and Earth-Sun
Jere H. Jenkins et al.,

Unexplained periodic fluctuations in the decay rates of Si-32 and Ra-226
have been reported by groups at Brookhaven National Laboratory (Si-32),
and at the Physikalisch-Technische-Bundesandstalt in Germany (Ra-226). We
show from an analysis of the raw data in these experiments that the
observed fluctuations are strongly correlated in time, not only with each
other, but also with the distance between the Earth and the Sun. Some
implications of these results are also discussed, including the suggestion
that discrepancies in published half-life determinations for these and
other nuclides may be attributable in part to differences in solar
activity during the course of the various experiments, or to seasonal
variations in fundamental constants.

Oscillations in radioactive exponential decay
T.M. Semkov et al.
Physics Letters B 675,5 (2009) 415­419

Several older and recent reports provided evidence for the oscillatory
character of the exponential decay law in radioactive decay and attempted
to explain it with basic physics. We show here that the measured effects
observed in some of the cases, namely in the decay of 226Ra, 32Si in
equilibrium, and 36Cl, can be explained with the temperature variations.

(more lit. there)


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