neutrinos

Physicists Focus on Neutrinos With New Telescope

admin — Fri, 17 Nov 2023 14:10:41 +0000

Physicists Focus on Neutrinos With New Telescope admin Fri, 11/17/2023 - 09:10

Georgia Tech scientists will soon have another way to search for neutrinos, those hard-to-detect, high-energy particles speeding through the cosmos that hold clues to massive particle accelerators in the universe — if researchers can find them.

“The detection of a neutrino source or even a single neutrino at the highest energies is like finding a holy grail,” says Professor Nepomuk Otte, the principal investigator for the Trinity Demonstrator telescope that was recently built by his group and collaborators, and was designed to detect neutrinos after they get stopped within the Earth.

The National Science Foundation (NSF)-funded effort will eventually create “the world’s most sensitive ultra-high energy neutrino telescope.” The Trinity Demonstrator is the first step toward an array of 18 telescopes located at three sites, each on top of a high mountain.

Earlier in the year, Otte’s group flew a neutrino telescope tethered to a massive NASA-funded balloon — though a leak brought the telescope down earlier than planned. The effort was part of the EUSO-SPB2 collaboration, which wants to study cosmic-particle accelerators with detectors in space.

“This was the first time our group had built an instrument for a balloon mission,” Otte says. “And the big question was if it would work at the boundary to space at -40F and in a vacuum. Even though we only flew 37 hours (of a 50-hour mission), we could show that our instrument worked as expected. We even accomplished some key measurements, like making a measurement of the background light, which no one has done before.”

The search for neutrinos

Otte is the second Georgia Tech physicist to lead a search for neutrinos. Professor Ignacio Taboada is the spokesperson for IceCube, an NSF neutrino observatory located at the South Pole. IceCube uses thousands of sensors buried in the ice to detect neutrinos.

Meanwhile, Trinity telescopes will be especially sensitive to higher-energy neutrinos. “With Trinity, we can potentially open a new, entirely unexplored window in astronomy,” Otte says. “IceCube gives us a couple of good pointers on what to observe. That is also why we modified the building of the Trinity Demonstrator to point toward the only two high-energy neutrino sources” already identified by IceCube scientists.

‘Cherenkov lights’ illuminate ‘air showers’

The Trinity Demonstrator telescope is not your typical astronomy telescope. Instead of looking into the sky, it is looking at the horizon, waiting for a flash of light to happen that only lasts tens of billionths of a second.

That flash is at the end of a chain of events that happens when a high-energy neutrino enters the Earth under a shallow angle. Upon penetrating Earth and traveling along a straight line for a hundred miles, the neutrino eventually interacts inside the Earth, producing a tau particle, which is like a short-lived massive electron.

The tau continues to travel through the Earth, and when it bounces out of the ground, it decays into millions of electrons and positrons, which zip through the air. Because the electrons and positrons travel faster than the speed of light in the air, they emit Cherenkov light, the short flash of light the Trinity Demonstrator telescope detects. Using computer algorithms, the recorded Cherenkov flashes are analyzed to reconstruct the energy and arrival direction of the neutrino.

Otte and his team of Georgia Tech postdoctoral and graduate scholars developed and built the Trinity Demonstrator. Undergraduate students have also had significant responsibilities in designing its optics. “It is good for the students because they are involved in all aspects of the experiment. In big collaborations, you are an expert on one aspect only,” Otte says.

The largest collaboration Otte is currently involved with is the Cherenkov Telescope Array, which involves more than 2,000 researchers. That planned international project will involve 60 next-generation gamma-ray telescopes in Chile and on the Canary Island of La Palma.

Next year, Otte says he and his researchers will apply for funding to build a much bigger telescope, which will be the foundation for the NSF 18-telescope array. For now, the team is busy observing with the Trinity Demonstrator atop Frisco Peak in Utah.

“With a bit of luck, we will detect the first neutrino source at these energies,” Otte said.

Funding: National Science Foundation (NSF)

Subtitle

Physics Professor Nepomuk Otte and students have developed the Trinity Demonstrator to search for sources of high-energy neutrinos that contain clues to the early universe.

Summary sentence

Physics Professor Nepomuk Otte and students have developed the Trinity Demonstrator to search for sources of high-energy neutrinos that contain clues to the early universe.

Summary

Physics Professor Nepomuk Otte and students have developed the Trinity Demonstrator to search for sources of high-energy neutrinos that contain clues to the early universe.

Dateline

Thu, 11/16/2023 - 12:00

renay.san@cos.gatech.edu

Contact

Writer: Renay San Miguel
Communications Officer II/Science Writer
College of Sciences
404-894-5209

Editor: Jess Hunt-Ralston

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Nepomuk Otte

neutrinos

Tau Neutrinos

Ignacio Taboada

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Science and Technology

IceCube Detects High-Energy Neutrino Emission from Milky Way

admin — Thu, 29 Jun 2023 18:11:31 +0000

IceCube Detects High-Energy Neutrino Emission from Milky Way admin Thu, 06/29/2023 - 14:11

Georgia Institute of Technology Physics Professor and Center for Relativistic Astrophysics member Ignacio Taboada serves as spokesperson for IceCube Collaboration.

Our Milky Way galaxy is an awe-inspiring feature of the night sky, viewable with the naked eye as a horizon-to-horizon hazy band of stars. Now, for the first time, the IceCube Neutrino Observatory has produced an image of the Milky Way using neutrinos — tiny, ghostlike astronomical messengers.

In an article to be published June 30, 2023, in the journal Science, the IceCube Collaboration, an international group of over 350 scientists, presents evidence of high-energy neutrino emission from the Milky Way.

The detected high-energy neutrinos hold energies millions to billions of times higher than those produced by the fusion reactions that power stars.

IceCube was built and is operated with National Science Foundation (NSF) funding and additional support from the fourteen countries that host institutional members of the IceCube Collaboration. IceCube Observatory searches for signs of high-energy neutrinos originating from our galaxy and beyond, out to the farthest reaches of the universe.

A cubic-kilometer neutrino detector operating at Amundsen-Scott South Pole Station observes these high-energy neutrinos, explains Ignacio Taboada, spokesperson for IceCube and a physics professor at Georgia Institute of Technology. “IceCube is truly unique,” Taboada says. “Built deep in Antarctic ice, its over 5,000 light sensors search for the flashes of blue light — Cherenkov radiation produced by neutrinos in the upper atmosphere, the Milky Way, and deep into the cosmos.”

Searching the southern sky

“What's intriguing is that, unlike the case for light of any wavelength, in neutrinos, the universe outshines the nearby sources in our own galaxy," says Francis Halzen, a professor of physics at the University of Wisconsin–Madison and principal investigator of IceCube.

"As is so often the case, significant breakthroughs in science are enabled by advances in technology," says Denise Caldwell, director of NSF's Physics Division. "The capabilities provided by the highly sensitive IceCube detector, coupled with new data analysis tools, have given us an entirely new view of our galaxy — one that had only been hinted at before. As these capabilities continue to be refined, we can look forward to watching this picture emerge with ever-increasing resolution, potentially revealing hidden features of our galaxy never before seen by humanity."

Interactions between cosmic rays — high-energy protons and heavier nuclei, also produced in our galaxy, and galactic gas and dust inevitably produce both gamma rays and neutrinos. Given the observation of gamma rays from the galactic plane, the Milky Way was expected to be a source of high-energy neutrinos.

“A neutrino counterpart has now been measured, thus confirming what we know about our galaxy and cosmic ray sources,” says Steve Sclafani, a physics Ph.D. student at Drexel University, IceCube member, and co-lead analyzer.

The search focused on the southern sky, where the bulk of neutrino emission from the galactic plane is expected near the center of our galaxy. However, until now, the background of muons and neutrinos produced by cosmic-ray interactions with the Earth’s atmosphere posed significant challenges.

To overcome them, IceCube collaborators at Drexel University developed analyses that select for "cascade" events, or neutrino interactions in the ice that result in roughly spherical showers of light. Because the deposited energy from cascade events starts within the instrumented volume, contamination of atmospheric muons and neutrinos is reduced. Ultimately, the higher purity of the cascade events gave a better sensitivity to astrophysical neutrinos from the southern sky.

Machine learning in the Milky Way

However, the final breakthrough came from the implementation of machine learning methods, developed by IceCube collaborators at TU Dortmund University, that improve the identification of cascades produced by neutrinos as well as their direction and energy reconstruction. The observation of neutrinos from the Milky Way is a hallmark of the emerging critical value that machine learning provides in data analysis and event reconstruction in IceCube.

“The improved methods allowed us to retain over an order of magnitude more neutrino events with better angular reconstruction, resulting in an analysis that is three times more sensitive than the previous search,” says IceCube member, TU Dortmund physics Ph.D. student, and co-lead analyzer Mirco Hünnefeld.

The dataset used in the study included 60,000 neutrinos spanning 10 years of IceCube data, 30 times as many events as the selection used in a previous analysis of the galactic plane using cascade events. These neutrinos were compared to previously published prediction maps of locations in the sky where the galaxy was expected to shine in neutrinos.

The maps included one made from extrapolating Fermi Large Area Telescope gamma-ray observations of the Milky Way and two alternative maps identified as KRA-gamma by the group of theorists who produced them.

“This long-awaited detection of cosmic ray-interactions in the galaxy is also a wonderful example of what can be achieved when modern methods of knowledge discovery in machine learning are consistently applied.” says Wolfgang Rhode, professor of physics at TU Dortmund University, IceCube member, and Hünnefeld’s advisor.

The power of machine learning offers great future potential, bringing other observations closer within reach.

“The strong evidence for the Milky Way as a source of high-energy neutrinos has survived rigorous tests by the collaboration,” says Taboada, the IceCube spokesperson. “Now, the next step is to identify specific sources within the galaxy.”

These and other questions will be addressed in planned follow-up analyses by IceCube.

“Observing our own galaxy for the first time using particles instead of light is a huge step,” says Naoko Kurahashi Neilson, professor of physics at Drexel University, IceCube member, and Sclafani’s advisor. “As neutrino astronomy evolves, we will get a new lens with which to observe the universe.”

About IceCube Neutrino Observatory

The IceCube Neutrino Observatory is funded and operated primarily through an award from the National Science Foundation to the University of Wisconsin–Madison. The IceCube Collaboration, with over 350 scientists in 58 institutions from around the world, runs an extensive scientific program that has established the foundations of neutrino astronomy. IceCube’s research efforts, including critical contributions to the detector operation, are funded by agencies in Australia, Belgium, Canada, Denmark, Germany, Italy, Japan, New Zealand, Republic of Korea, Sweden, Switzerland, Taiwan, the United Kingdom, and the United States, including NSF. IceCube construction was also funded with significant contributions from the National Fund for Scientific Research (FNRS & FWO) in Belgium; the Federal Ministry of Education and Research (BMBF) and the German Research Foundation (DFG) in Germany; the Knut and Alice Wallenberg Foundation, the Swedish Polar Research Secretariat, and the Swedish Research Council in Sweden; and the Wisconsin Alumni Research Fund.

About Georgia Institute of Technology

The Georgia Institute of Technology, or Georgia Tech, is one of the top public research universities in the U.S., developing leaders who advance technology and improve the human condition. The Institute offers business, computing, design, engineering, liberal arts, and sciences degrees. Its more than 45,000 undergraduate and graduate students, representing 50 states and more than 148 countries, study at the main campus in Atlanta, at campuses in France and China, and through distance and online learning. As a leading technological university, Georgia Tech is an engine of economic development for Georgia, the Southeast, and the nation, conducting more than $1 billion in research annually for government, industry, and society.

Subtitle

Our galaxy is seen through a new lens as NSF IceCube Collaboration presents evidence of high-energy neutrino emission from the Milky Way

Summary sentence

Our galaxy is seen through a new lens as NSF IceCube Collaboration presents evidence of high-energy neutrino emission from the Milky Way

Summary

High-energy neutrinos — with energies millions to billions of times higher than those produced by the fusion reactions that power stars — have been detected by the IceCube Neutrino Observatory, a gigaton detector operating at the Amundsen-Scott South Pole Station. It was built and is operated with National Science Foundation (NSF) funding and additional support from the fourteen countries that host institutional members of the IceCube Collaboration.

Dateline

Thu, 06/29/2023 - 12:00

jess@cos.gatech.edu

Contact

Science Contacts:

Francis Halzen, IceCube Principal Investigator
Vilas Research Professor and Gregory Breit Distinguished Professor of Physics
Wisconsin IceCube Particle Astrophysics Center, University of Wisconsin–Madison

Ignacio Taboada, IceCube Spokesperson
Professor of Physics, Georgia Institute of Technology

Press Contacts:

Georgia Institute of Technology
Jess Hunt-Ralston
Director of Communications, College of Sciences

IceCube Press
press@icecube.wisc.edu

NSF Media Affairs
media@nsf.gov

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IceCube Collaboration

NSF

Ignacio Taboada

IceCube Neutrino Observatory

neutrinos

Milky Way

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Science and Technology

Mercury ID

668279

Source updated

Thu, 06/29/2023 - 14:08

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Physicists Focus on Neutrinos With New Telescope

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