How Earth Stops High-Energy Neutrinos

Monday, November 27, 2017

Efforts of Berkeley Lab scientists are key in new analysis of data from Antarctic experiment

Neutrinos are abundant subatomic particles that are famous for passing through anything and everything, only very rarely interacting with matter. About 100 trillion neutrinos pass through your body every second.

Now, scientists have demonstrated that the Earth stops energetic neutrinos—they do not go through everything. These high-energy neutrino interactions were seen by the IceCube detector, an array of 5,160 basketball-sized optical sensors deeply encased within a cubic kilometer of very clear Antarctic ice near the South Pole.

Watch a video on the new findings below:

IceCube’s sensors do not directly observe neutrinos, but instead measure flashes of blue light, known as Cherenkov radiation, emitted by muons and other fast-moving charged particles, which are created when neutrinos interact with the ice, and by the charged particles produced when the muons interact as they move through the ice. By measuring the light patterns from these interactions in or near the detector array, IceCube can estimate the neutrinos’ directions and energies.

The study, published in the Nov. 22 issue of the journal Nature, was led by researchers at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and UC Berkeley.

Spencer Klein, who leads Berkeley Lab’s IceCube research team, commented “This analysis is important because it shows that IceCube can make real contributions to particle and nuclear physics, at energies above the reach of current accelerators.”

Sandra Miarecki, who performed much of the data analysis while working toward her PhD as an IceCube researcher at Berkeley Lab and UC Berkeley, said, “It’s a multidisciplinary idea.” The analysis required input from geologists who have created models of the Earth’s interior from seismic studies. Physicists have used these models to help predict how neutrinos are absorbed in the Earth.

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Editor: 
Glenn Roberts Jr.
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