Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Detector at the South Pole explores the mysterious neutrinos

16.04.2015

Neutrinos are a type of particle that pass through just about everything in their path from even the most distant regions of the universe. The Earth is constantly bombarded by billions of neutrinos, which zip right through the entire globe, houses, animals, people - everything.

Only very rarely do they react with matter, but the giant IceCube experiment at the South Pole can detect when there is a collision between neutrinos and atoms in the ice using a network of detectors. New research results from the Niels Bohr Institute among others have measured the neutrinos at the South Pole and have calculated some of the physical properties of the otherwise exotic and poorly understood particles. The results are published in the scientific journal Physical Review D.


Jason Koskinen is shown at the South Pole. In the background is the IceCube Lab. All data from the instruments deep down in the ice comes up through the two "towers" and into the computer center, where the first analyses are done.

Credit: T. Waldemaier

Neutrinos are among nature's most abundant particles. Their number far exceeds the number of atoms in the entire universe - yet we know little about them. Neutrinos are a type of particle created in the Big Bang and are also produced in the Sun's interior and in violent events like supernovae, which are exploding stars. Neutrinos are also called 'ghost particles' because they basically do not interact with matter, but pass undisturbed through everything in their path.

Instruments at the South Pole

Researchers from 44 institutions in 12 countries are part of an international project, IceCube at the South Pole to study the mysterious particles with the strange properties.

IceCube is an enormous particle detector located deep in the ice at the South Pole. The instruments in the detector are comprised of 86 cables each with 60 digital Optical Modules (extremely sensitive light sensors). Each cable is lowered down into a hole, which is melted through the 2½ km ice sheer using a hot water drill. The detector is located deep below the surface - it starts 1½ km below the ice and ends at the bottom at a depth of 2½ km.

The detector's enormous size of a cubic kilometer is necessary because neutrinos interact extremely weakly with matter, so it is only rarely that they collide with the atoms in the ice. When they finally collide, charged particles are created, which emit radiation that can be detected by the extremely sensitive Digital Optical Modules.

"In the Ice Cube project we have registered about 35 neutrinos, which are very likely to have come distant regions in space. They have a very high energy and because they have not interacted during their long journey, they can carry information from the most distant parts of the universe. In addition to the rare cosmic neutrinos, we are also studying the neutrinos created in the Earth's atmosphere in order to unravel the physical properties of neutrinos," says Jason Koskinen, Assistant Professor and head of the IceCube Group at the Niels Bohr Institute, University of Copenhagen.

From the North Pole to the South Pole

When particles (protons) with high energy - from violent events in the cosmos like supernovae and quasars hit the Earth's atmosphere, a burst of neutrinos is formed, which passes through the Earth. The neutrinos formed over the North Pole pass straight through the Earth and very small proportion of them hit the ice at the South Pole, where the IceCube detector registers the collisions.

Neutrinos are very light particles and for many years it was believed that they were completely massless. It is now believed that there are three types of neutrinos (electron, muon and tau neutrinos), each with their specific mass, which is incredibly small - less than a millionth of the mass of an electron.

"The neutrinos created in the atmosphere over the North Pole are mostly muon neutrinos. On their way through the Earth's 13,000 km, the muon neutrinos undergo quantum fluctuations that can change them into another type of neutrino, tau neutrinos, before they are finally detected by IceCube on the other side of the globe. We can now study these effects in much greater detail than before and in this way we can gain new insights into their physical characteristics," explains Jason Koskinen.

Atmospheric neutrinos

The research group has now studied atmospheric neutrinos in the IceCube detector at the South Pole for three years and have analysed 5,200 interactions between atmospheric neutrinos and atoms in the ice.

"We have confirmed that neutrinos undergo fluctuations - even at high energy levels and we have calculated how much they exhibit these oscillations. In this study, we have only measured muon neutrinos and in comparison to how many muon neutrinos form in in the atmosphere and pass through the Earth, we only see a fraction at the South Pole. The explanation is that the muon neutrinos undergo quantum fluctuations that change them into tau neutrinos and we do not see those. If they had not changed, we would see them all. Our calculations show that 20 percent have undergone quantum fluctuations and changed from muon neutrinos to another type of neutrino as they pass through the Earth," explains Jason Koskinen.

Messengers from the universe

And then what, you might ask? "Because we basically want to learn more about these strange particles that are everywhere in the universe and whose properties we still do not fully understand. Because neutrinos come from the cosmos, we could use them for astronomical observations and gain new insights into the structure of the universe," says Jason Koskinen.

###

Article: http://journals.aps.org/prd/abstract/10.1103/PhysRevD.91.072004

Contact:

Jason Koskinen, Assistant Professor and head of the IceCube Group at the Niels Bohr Institute, University of Copenhagen, +45 2128-9061, koskinen@nbi.ku.dk

Morten Medici, PhD student, IceCube Group at the Niels Bohr Institute, University of Copenhagen, +45 3532-5454, +45 6151-6464, mmedici@nbi.ku.dk

Gertie Skaarup | EurekAlert!

More articles from Physics and Astronomy:

nachricht X-ray photoelectron spectroscopy under real ambient pressure conditions
28.06.2017 | National Institutes of Natural Sciences

nachricht New photoacoustic technique detects gases at parts-per-quadrillion level
28.06.2017 | Brown University

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: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Supersensitive through quantum entanglement

28.06.2017 | Physics and Astronomy

X-ray photoelectron spectroscopy under real ambient pressure conditions

28.06.2017 | Physics and Astronomy

Mice provide insight into genetics of autism spectrum disorders

28.06.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>