Published in Science: Evidence for High-Energy Extraterrestrial Neutrinos at the IceCube Detector

Image: IceCube Collaboration. Reprinted with permission from AAAS.

The IceCube Neutrino Observatory, a particle detector buried in the Antarctic ice, is a demonstration of the power of the human passion for discovery, where scientific ingenuity meets technological innovation. Today, nearly 25 years after the pioneering idea of detecting neutrinos in ice, the IceCube Collaboration announces the observation of 28 very high-energy particle events that constitute the first solid evidence for astrophysical neutrinos from cosmic accelerators. Details of this research will be published tomorrow, November 22, in Science.

IceCube, run by the international IceCube Collaboration and headquartered at the Wisconsin IceCube Particle Astrophysics Center (WIPAC) at UW–Madison, was designed to accomplish two major scientific goals: measure the flux, or rate, of high-energy neutrinos and try to identify some of their sources. The analysis presented in Science reveals the first high-energy neutrino flux ever observed, a highly statistically significant signal (more than 4 sigma) that meets expectations for neutrinos originating in cosmic accelerators.

“This is the first indication of very high-energy neutrinos coming from outside our solar system, with energies more than one million times those observed in 1987 in connection with a supernova seen in the Large Magellanic Cloud,” says Francis Halzen, principal investigator of IceCube and the Hilldale and Gregory Breit Distinguished Professor of Physics at UW–Madison. “It is gratifying to finally see what we have been looking for. This is the dawn of a new age of astronomy.”

Prof. Halzen, who also serves as the interim director of WIPAC, was the first to propose the detection of neutrinos in ice back in the late 1980s. The search for high-energy neutrinos from the cosmos drew him and a growing international team to build AMANDA, the Antarctic Muon and Neutrino Detector Array. It was the proof-of-concept for the first cubic-kilometer neutrino telescope, IceCube, which was completed in December 2010 after seven years of construction at the South Pole. IceCube was built under a Major Research Equipment and Facilities Construction grant from the National Science Foundation, which was also the main funding agency for AMANDA. In both cases, other partner funding agencies around the world contributed to the project.

The leading role of the UW–Madison team in IceCube led to the establishment of WIPAC, a new scientific center within the Graduate School, with faculty based in the Departments of Physics and Astronomy. WIPAC is the primary institution overseeing IceCube, responsible for maintaining and operating the detector to maximize data output and supporting the international collaboration in meaningful ways.

“The construction of IceCube was an exciting and challenging time, and many people from UW–Madison played an important role. IceCube would not have been possible without the support of the Graduate School or without the engineering capabilities provided by the Physical Sciences Laboratory,” says Prof. Albrecht Karle, the IceCube Associate Director for Science and Instrumentation. “Now we are starting an even more exciting time, as IceCube is releasing new data at a rapid pace. And our researchers are again major contributors to many of the ongoing studies, as in the case of the analysis now published in Science.

Three postdocs at WIPAC, Claudio Kopper, Naoko Kurahashi and Nathan Whitehorn, are the corresponding authors of this new research by the IceCube Collaboration.

+ info “Evidence for High-Energy Extraterrestrial Neutrinos at the IceCube Detector,” IceCube Collaboration: M.G. Aartsen et al. Science 342, 1242856 (2013).,

IceCube Collaboration press release

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