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The Strange Case of Solar Flares and Radioactive Decay Rates
DarkKnightRadick writes "Current models for radioactive decay have been challenged by, of all sources, the sun. According to the article, 'On Dec 13, 2006, the sun itself provided a crucial clue, when a solar flare sent a stream of particles and radiation toward Earth. Purdue nuclear engineer Jere Jenkins, while measuring the decay rate of manganese-54, a short-lived isotope used in medical diagnostics, noticed that the rate dropped slightly during the flare, a decrease that started about a day and a half before the flare.' This is important because the rate of decay is very important not just for antique dating, but also for cancer treatment, time keeping, and the generation of random numbers. This isn't a one time measurement, either. 'Checking data collected at Brookhaven National Laboratory on Long Island and the Federal Physical and Technical Institute in Germany, they came across something even more surprising: long-term observation of the decay rate of silicon-32 and radium-226 seemed to show a small seasonal variation. The decay rate was ever so slightly faster in winter than in summer.'"
No, this does not get you down to a 6000-year old Earth. Sorry.
Only Pink Hat Linux. I've never gotten more trim since I made the switch to Manlyuntu.
One way to double-check the seasonal variation effect is to look at the output level on radioisotope power sources in spacecraft. Cooper (2008) found no relationship between radioactive decay and distance to the sun.
The sun has a cycle of it's own (about 1 month). They did a much more accurate study and found the decay rate is tightly correlated to the sun's cycle.
Longer version:
The theory now is that it has to do with the neutrino flux. As we move further from the sun the flux goes down by 1/R^2. We saw that fluctuation first. But the neutrino flux also varies with the solar cycle which is independent of the earth's temperature.
This is very very cool experimental physics. Kudo's to them!
Neutrino density is not going to vary a lot by hemisphere because the planet is fairly transparent to neutrinos. However, the Earth as a whole (including the southern hemisphere) is some 3% closer to the sun during the winter (January) than during the summer.
When our name is on the back of your car, we're behind you all the way!
They found the same results in historical data of various labs. That of course does not rule out such a mundane reason, it makes it less likely.
I agree that there are certainly seasonal variations in labs, even if you try to keep it as constant as possible. But for starters the air in the lab has to be refreshed all the time, and this air comes from the outside. I can imagine the composition changes between summer and winter (plants don't grow in winter).
The 33-day cycle another replier mentioned is interesting of course, as it correlates with a solar cycle and no normal human cycles.
A multi-year cycle correlating to solar spots could be interesting.
Effects correlating to known solar flares too.
Overheard in a museum:
Boy: Mister, how old is that dinosaur skeleton?
Curator: [after some mumbling and finger counting] 60 million and four years, eight months and sixteen days.
Boy's mother: How can you know so accurately?
Curator: Well, in the training course they told me it was 60 million years old. That was when I joined, which would be back in January 2006...
Confucius say, "Find worm in apple - bad. Find half a worm - worse."
I'm pretty sure that's exactly why darkmeleon suggested doing the experiment in the southern hemisphere: it's a great way to either prove or disprove those saying that temperature variation is what's causing the change in measured decay rates: if it's caused by the weather's effect on the equipment, then the effect should be out of phase in the southern hemisphere than the northern. If, on the other hand, the increase/decrease happens in the same months, then it confirms that it's the proximity to the sun that's causing it.