New system could predict solar flares, give advance warning to help protect power grids

decay rate of chlorine 36; changes in the decay rate were found to match changes in the Earth-sun distance and Earth’s exposure to different parts of the sun itself, Fischbach said.

Large solar flares may produce a “coronal mass ejection” of highly energetic particles, which can interact with the Earth’s magnetosphere, triggering geomagnetic storms that sometimes knock out power. The sun’s activity is expected to peak over the next year or so as part of an 11-year cycle that could bring strong solar storms.

Solar storms can be especially devastating if the flare happens to be aimed at the Earth, hitting the planet directly with powerful charged particles. A huge solar storm, called the Carrington event, hit the Earth in 1859, a time when the only electrical infrastructure consisted of telegraph lines.

“There was so much energy from this solar storm that the telegraph wires were seen glowing and the aurora borealis appeared as far south as Cuba,” Fischbach said. “Because we now have a sophisticated infrastructure of satellites, power grids and all sort of electronic systems, a storm of this magnitude today would be catastrophic. Having a day and a half warning could be really helpful in averting the worst damage.”

Satellites, for example, might be designed so that they could be temporarily shut down and power grids might similarly be safeguarded before the storm arrived.

Researchers have recorded data during ten solar flares since 2006, seeing the same pattern.

“We have repeatedly seen a precursor signal preceding a solar flare,” Fischbach said. “We think this has predictive value.”

The release notes that the Purdue experimental setup consists of a radioactive source - manganese 54 - and a gamma-radiation detector. As the manganese 54 decays, it turns into chromium 54, emitting a gamma ray, which is recorded by the detector to measure the decay rate.

Purdue has filed a U.S. patent application for the concept.

Research findings show evidence that the phenomenon is influenced by the Earth’s distance from the sun; for example, decay rates are different in January and July, when the Earth is closest and farthest from the sun, respectively.

“When the Earth is farther away, we have fewer solar neutrinos and the decay rate is a little slower,” Jenkins said. “When we are closer, there are more neutrinos, and the decay a little faster.”

Researchers also have recorded both increases and decreases in decay rates during solar storms. “What this is telling us is that the sun does influence radioactive decay,” Fischbach said.

Neutrinos have the least mass of any known subatomic particle, yet it is plausible that they are somehow affecting the decay rate, he said.

English physicist Ernest Rutherford, known as the father of nuclear physics, in the 1930s conducted experiments indicating the radioactive decay rate is constant, meaning it cannot be altered by external influences.

“Since neutrinos have essentially no mass or charge, the idea that they could be interacting with anything is foreign to physics,” Jenkins said. “So, we are saying something that doesn’t interact with anything is changing something that can’t be changed. Either neutrinos are affecting decay rate or perhaps an unknown particle is.”

Jenkins discovered the effect by chance in 2006, when he was watching television coverage of astronauts spacewalking at the International Space Station. A solar flare had erupted and was thought to possibly pose a threat to the astronauts. He decided to check his equipment and discovered that a change in decay-rate had preceded the solar flare.

Further research is needed to confirm the findings and to expand the work using more sensitive equipment, he said.

Jenkins and Fischbach have previously collaborated with Peter Sturrock, a professor emeritus of applied physics at Stanford University and an expert on the inner workings of the sun, to examine data collected at Brookhaven on the decay rate of radioactive isotopes silicon-32 and chlorine-36.

The team reported in 2010 in Astroparticle Physics that the decay rate for both isotopes varies in a 33-day recurring pattern, which they attribute to the rotation rate of the sun’s core.

The group found evidence of the same annual and 33-day effect in radium-226 data taken at the Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig, Germany, and those findings were published in 2011. They also found an additional 154-day recurring pattern in both the Brookhaven and PTB data, published in 2011, which they believe to be solar related and similar to a known solar effect called a Rieger periodicity.

— Read more in Jere H. Jenkins et al., “Additional experimental evidence for a solar influence on nuclear decay rates,” Astroparticle Physics (8 August 2012)