[tt] do nuclear decay rates depend on our distance from the sun?

[Eugen Leitl]

(((wow, if true)))

http://arxivblog.com/?p=596

Do nuclear decay rates depend on our distance from the sun?

August 29th, 2008 | by KFC |

Here’s an interesting conundrum involving nuclear decay rates.

We think that the decay rates of elements are constant regardless of the
ambient conditions (except in a few special cases where beta decay can be
influenced by powerful electric fields).

So that makes it hard to explain the curious periodic variations in the decay
rates of silicon-32 and radium-226 observed by groups at the Brookhaven
National Labs in the US and at the Physikalisch-Technische Bundesandstalt in
Germany in the 1980s.

Today, the story gets even more puzzling. Jere Jenkins and pals at Purdue
University in Indiana have re-analysed the raw data from these experiments
and say that the modulations are synchronised with each other and with
Earth’s distance from the sun. (Both groups, in acts of selfless dedication,
measured the decay rates of siliocn-32 and radium-226 over a period of many
years.)

In other words, there appears to be an annual variation in the decay rates of
these elements.

Jenkins and co put forward two theories to explain why this might be
happening.

First,  they say a theory developed by John Barrow at the University of
Cambridge in the UK and Douglas Shaw at the University of London, suggests
that the sun produces a field that changes the value of the fine structure
constant on Earth as its distance from the sun varies during each orbit. Such
an effect would certainly cause the kind of an annual variation in decay
rates that Jenkins and co highlight.

Another idea is that the effect is caused by some kind of interaction with
the neutrino flux from the sun’s interior, which could be tested by carrying
out the measurements close to a nuclear reactor (which would generate its own
powerful neutrino flux).

It turns out, that the notion of that nuclear decay rates are constant has
been under attack for some time. In 2006, Jenkins says the decay rate of
manganese-54 in their lab decreased dramtically during a solar flare on 13
December.

And numerous groups disagree over the decay rate for elements such as
titanium-44, silicon-32 and cesium-137. Perhaps they took their data at
different times of the year.

Keep em peeled beause we could hear more about this. Interesting stuff.

Ref: arxiv.org/abs/0808.3283: Evidence for Correlations Between Nuclear Decay
Rates and Earth-Sun Distance