Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


New Data From Antarctic Detector Firms Up Cosmic Neutrino Sighting


Researchers using the IceCube Neutrino Observatory have sorted through the billions of subatomic particles that zip through its frozen cubic-kilometer-sized detector each year to gather powerful new evidence in support of 2013 observations confirming the existence of cosmic neutrinos.

The evidence is important because it heralds a new form of astronomy using neutrinos, the nearly massless high-energy particles generated in nature’s accelerators: black holes, massive exploding stars and the energetic cores of galaxies.

IceCube Collaboration

One of the highest-energy neutrino events from a survey of the northern sky superimposed on a view of the IceCube Lab (ICL) at the South Pole.

In the new study, the detection of 21 ultra high-energy muons — secondary particles created on the very rare occasions when neutrinos interact with other particles —provides independent confirmation of astrophysical neutrinos from our galaxy as well as cosmic neutrinos from sources outside the Milky Way.

The observations were reported today (Aug. 20, 2015) in a paper published in the journal Physical Review Letters by the IceCube Collaboration, which called the data an “unequivocal signal” for astrophysical neutrinos, ultra high-energy particles that have traversed space unimpeded by stars, planets, galaxies, magnetic fields or clouds of interstellar dust — phenomena that, at very high energies, significantly attenuate more mundane particles like photons.

Because they have almost no mass and no electric charge, neutrinos can be very hard to detect and are only observed indirectly when they collide with other particles to create muons, telltale secondary particles. What’s more, there are different kinds of neutrinos produced in different astrophysical processes.

The IceCube Collaboration, a large international consortium headquartered at the University of Wisconsin-Madison, has taken on the huge challenge of sifting through a mass of observations to identify perhaps a few dozen of the highest-energy neutrinos that have traveled from sources in the Milky Way and beyond our galaxy.

Those high-energy neutrinos, scientists believe, are created deep inside some of the universe’s most violent phenomena. The particles created in these events, including neutrinos and cosmic rays, are accelerated to energy levels that exceed the record-setting earthbound accelerators such as the Large Hadron Collider (LHC) by a factor of more than a million.

They are prized by astrophysicists because the information they hold is pristine, unchanged as the particles travel millions of light years between their sources and Earth. The ability to study the highest-energy neutrinos promises insight into a host of problems in physics, including how nature builds powerful and efficient particle accelerators in the universe.

The latest observations were made by pointing the Ice Cube Observatory — composed of thousands of optical sensors sunk deep beneath the Antarctic ice at the South Pole — through the Earth to observe the Northern Hemisphere sky. The Earth serves as a filter to help weed out a confusing background of muons created when cosmic rays crash into the Earth’s atmosphere.

“Looking for muon neutrinos reaching the detector through the Earth is the way IceCube was supposed to do neutrino astronomy and it has delivered,” explains Francis Halzen, a UW-Madison professor of physics and the principal investigator of IceCube. “This is as close to independent confirmation as one can get with a unique instrument.”

Between May 2010 and May 2012, IceCube recorded more than 35,000 neutrinos. However, only about 20 of those neutrino events were clocked at energy levels indicative of astrophysical or cosmic sources.

The results are meaningful because, using the different technique, they reaffirm the IceCube Observatory’s ability to sample the ghostlike neutrinos. By instrumenting a cubic kilometer of deep Antarctic ice, scientists were able to make a detector big enough to capture the signature of the rare neutrino collision.

When that rare smashup occurs, it creates a muon, which, in turn, leaves a trail of Cherenkov light that faithfully mirrors the trajectory of the neutrino. The “optical sonic booms” created when neutrinos smash into another particle are sensed by the optical sensors that make up the IceCube detector array and, in theory, can be used to point back to a source.

"This is an excellent confirmation of IceCube’s recent discoveries, opening the doors to a new era in particle physics," says Vladimir Papitashvili, astrophysics and geospace sciences program director in the National Science Foundation’s (NSF) Division of Polar Programs. "And it became possible only because of extraordinary qualities of Antarctic ice and NSF's ability to successfully tackle enormous scientific and logistical problems in the most inhospitable places on Earth."

But while the new observations confirm the existence of astrophysical neutrinos and the means to detect them using the IceCube Observatory, actual point sources of high-energy neutrinos remain to be identified.

Albrecht Karle, a UW-Madison professor of physics and a senior author of the Physical Review Letters report, notes that while the neutrino-induced tracks recorded by the IceCube detector have a good pointing resolution, within less than a degree, the IceCube team has not observed a significant number of neutrinos emanating from any single source.

The neutrinos observed in the latest search, however, have energy levels identical to those seen when the observatory sampled the sky of the Southern Hemisphere. That, says Karle, suggests that many of the potential sources of the highest-energy neutrinos are generated beyond the Milky Way. If there were a significant number of sources in our own galaxy, he notes, the IceCube detector would light up when observing the plane of our galaxy — the region where most neutrino-generating sources would likely be found.

“The plane of the galaxy is where the stars are. It is where cosmic rays are accelerated, so you would expect to see more sources there. But the highest-energy neutrinos we’ve observed come from random directions,” says Karle, whose former graduate student, Chris Weaver, is the corresponding author of the new study. “It is sound confirmation that the discovery of cosmic neutrinos from beyond our galaxy is real.”

IceCube is based at the Wisconsin IceCube Particle Astrophysics Center (WIPAC) at UW-Madison. The observatory was built with major support from the National Science Foundation as well as support from partner funding agencies worldwide. More than 300 physicists and engineers from the United States, Germany, Sweden, Belgium, Switzerland, Japan, Canada, New Zealand, Australia, the United Kingdom, Korea and Denmark are involved in the project.

Terry Devitt, (608) 262-8282,


Francis Halzen | newswise

Further reports about: Antarctic Antarctic ice Cosmic Earth IceCube Milky Way Neutrino cosmic rays energy levels

More articles from Physics and Astronomy:

nachricht First results of NSTX-U research operations
26.10.2016 | DOE/Princeton Plasma Physics Laboratory

nachricht Scientists discover particles similar to Majorana fermions
25.10.2016 | Chinese Academy of Sciences Headquarters

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

'Neighbor maps' reveal the genome's 3-D shape

27.10.2016 | Life Sciences

Gene therapy shows promise for treating Niemann-Pick disease type C1

27.10.2016 | Life Sciences

Solid progress in carbon capture

27.10.2016 | Power and Electrical Engineering

More VideoLinks >>>