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  • richardmitnick 2:43 pm on October 3, 2014 Permalink | Reply
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    From BNL: “Brookhaven and the Daya Bay Neutrino Experiment” 

    Brookhaven Lab

    October 1, 2014
    Karen McNulty Walsh

    The Daya Bay Collaboration, an international group of scientists studying the subtle transformations of subatomic particles called neutrinos, is publishing its first results on the search for a so-called sterile neutrino, a possible new type of neutrino beyond the three known neutrino “flavors,” or types. The existence of this elusive particle, if proven, would have a profound impact on our understanding of the universe, and could impact the design of future neutrino experiments. The new results, appearing in the journal Physical Review Letters, show no evidence for sterile neutrinos in a previously unexplored mass range. Read the collaboration press release.

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    Daya Bay
    Daya Bay
    The U.S. Department of Energy’s Brookhaven National Laboratory plays multiple roles in the Daya Bay experiment, ranging from management to data analysis. In addition to coordinating detector engineering and design efforts and developing software and analysis techniques, Brookhaven scientists perfected the “recipe” for a very special, chemically stable liquid that fills Daya Bay’s detectors and interacts with antineutrinos. This work at Daya Bay builds on a legacy of breakthrough neutrino research by Brookhaven Lab that has resulted in two Nobel Prizes in Physics.

    team
    Members of the BNL team on the Daya Bay Neutrino Project include: (seated, from left) Penka Novakova, Laurie Littenberg, Steve Kettell, Ralph Brown, and Bob Hackenburg; (standing, from left) Zhe Wang, Chao Zhang, Jiajie Ling, David Jaffe, Brett Viren, Wanda Beriguete, Ron Gill, Mary Bishai, Richard Rosero, Sunej Hans, and Milind Diwan. Missing from the picture are: Donna Barci, Wai-Ting Chan, Chellis Chasman, Debbie Kerr, Hide Tanaka, Wei Tang, Xin Qian, Minfang Yeh, and Elizabeth Worcester.

    Comments from U.S. Daya Bay Chief Scientist Steve Kettell

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    Steve Kettell

    This body of research is helping to unlock the secrets of the least understood constituents of matter—an important quest considering that neutrinos outnumber all other particle types with a billion neutrinos for every quark or electron.

    The fairly recent discovery that neutrinos have mass changes how we must think about the Standard Model of particle physics because it cannot be explained by that well-accepted description of all known particles and their interactions.

    sm
    The Standard Model of elementary particles, with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    Understanding the details of neutrino mass could have huge implications for our understanding of how the universe evolved. And those details—including how neutrinos oscillate, or switch from one flavor to another, are the essence of the research at Daya Bay and a key to unlocking these mysteries.

    The unusual properties of the known neutrinos, particularly their unique mass properties compared to other particles in the Standard Model, give us good reason to suspect that the universe may be full of such neutral particles of other flavors, such as the sterile neutrino. These particles could potentially help account for a large portion of matter in the universe that we cannot detect directly, so called dark matter.

    Daya Bay has been an exciting experiment to work on. It has been exquisitely designed and built, enabling us to make several important discoveries (first result and new result) and to search for these particles. And while the latest study from Daya Bay did not detect evidence of sterile neutrinos, it did greatly narrow the range in which we need to search. We will continue to exploit this beautiful experiment to further explore and understand the properties of the mysterious neutrino.

    The existence of neutrino mass and mixing leads to further deep questions, in particular whether neutrinos are responsible for the dominance of matter over antimatter in the universe. With the first results from Daya Bay this question now seems answerable with the long-baseline neutrino project planned at DOE’s Fermi National Accelerator Laboratory. Brookhaven scientists identified this scientific opportunity and continue to lead the development of this project, which has now been endorsed by recent national advisory panels as the highest priority domestic project in fundamental particle physics.
    See the full article here.

    BNL Campus

    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world.Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.
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  • richardmitnick 4:10 pm on October 1, 2014 Permalink | Reply
    Tags: , DAYA BAY,   

    From LBL: “News Center Hide & Seek: Sterile Neutrinos Remain Elusive” 

    Berkeley Logo

    Berkeley Lab

    October 1, 2014
    Kate Greene

    The Daya Bay Collaboration, an international group of scientists studying the subtle transformations of subatomic particles called neutrinos, is publishing its first results on the search for a so-called sterile neutrino, a possible new type of neutrino beyond the three known neutrino “flavors,” or types. The existence of this elusive particle, if proven, would have a profound impact on our understanding of the universe, and could impact the design of future neutrino experiments. The new results, appearing in the journal Physical Review Letters, show no evidence for sterile neutrinos in a previously unexplored mass range.

    There is strong theoretical motivation for sterile neutrinos. Yet, the experimental landscape is unsettled—several experiments have hinted that sterile neutrinos may exist, but the others yielded null results. Having amassed one of the largest samples of neutrinos in the world, the Daya Bay Experiment is poised to shed light on the existence of sterile neutrinos.

    Daya Bay
    Daya Bay

    reacotrs
    The reactors at Daya Bay in southeast China. Credit: Kam-Biu Luk

    The Daya Bay Experiment is situated close to the Daya Bay and Ling Ao nuclear power plants in China, 55 kilometers northeast of Hong Kong. These reactors produce a steady flux of antineutrinos that the Daya Bay Collaboration scientists use for research at detectors located at varying distances from the reactors. The collaboration includes more than 200 scientists from six regions and countries.

    The Daya Bay experiment began its operation on December 24, 2011. Soon after, in March 2012, the collaboration announced its first results: the observation of a new type of neutrino oscillation—evidence that these particles mix and change flavors from one type to others—and a precise determination of a neutrino “mixing angle,” called θ13, which is a definitive measure of the mixing of at least three mass states of neutrinos.

    The fact that neutrinos have mass at all is a relatively new discovery, as is the observation at Daya Bay that the electron neutrino is a mixture of at least three mass states. While scientists don’t know the exact values of the neutrino masses, they are able to measure the differences between them, or “mass splittings.” They also know that these particles are dramatically less massive than the well-known electron, though both are members of the family of particles called “leptons.”

    These unexpected observations have led to the possibility that the electrically neutral, almost undetectable neutrino could be a special type of matter and a very important component of the mass of the universe. Given that the nature of matter and in particular the property of mass is one of the fundamental questions in science, these new revelations about the neutrino make it clear that it is important to search for other light neutral particles that might be partners of the active neutrinos, and may contribute to the dark matter of the universe.

    Search for a light sterile neutrino

    The new Daya Bay paper describes the search for such a light neutral particle, the “sterile neutrino,” by looking for evidence that it mixes with the three known neutrino types—electron, muon, and tau. If, like the known flavors, the sterile neutrino also exists as a mixture of different masses, it would lead to mixing of neutrinos from known flavors to the sterile flavor, thus giving scientists proof of its existence. That proof would show up as a disappearance of neutrinos of known flavors.

    “The signal of sterile neutrinos, if exists, can be very subtle and easily confused by fluctuations,” says Yasuhiro Nakajima, Chamberlain Fellow in the Physics Division at the U.S. Department of Energy’s Lawrence Berkeley National Lab (Berkeley Lab) and one of the corresponding authors on the paper. “This investigation required very careful examination of the data. We developed multiple analysis methods and cross checked the analyses in many aspects.”

    Measuring disappearing neutrinos isn’t as strange as it seems. In fact that’s how Daya Bay scientists detect neutrino oscillations. The scientists count how many of the millions of quadrillions of electron antineutrinos produced every second by the six China General Nuclear Power Group reactors are captured by the detectors located in three experimental halls built at varying distances from the reactors. The detectors are only sensitive to electron antineutrinos. Calculations based on the number that disappear along the way to the farthest reactor give them information about how many have changed flavors.

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    Photomultiplier tubes in the Daya Bay detectors. Credit: Lawrence Berkeley Nat’l Lab – Roy Kaltschmidt

    The rate at which they transform is the basis for measuring the mixing angles (for example, θ13), and the mass splitting is determined by how the rate of transformation depends on the neutrino energy and the distance between the reactor and the detector.

    That distance is also referred to as the “baseline.” With six detectors strategically positioned at three separate locations to catch antineutrinos generated from the three pairs of reactors, Daya Bay provides a unique opportunity to search for a light sterile neutrino with baselines ranging from 360 meters to 1.8 kilometers.

    Daya Bay performed its first search for a light sterile neutrino using the energy dependence of detected electron antineutrinos from the reactors. Within the searched mass range for a fourth possible mass state, Daya Bay found no evidence for the existence of a sterile neutrino.

    This data represents the best world limit on sterile neutrinos over a wide range of masses and so far supports the standard three-flavor neutrino picture. Given the importance of clarifying the existence of the sterile neutrino, there are continuous quests by many scientists and experiments. The Daya Bay’s new result remarkably narrowed down the unexplored area.

    “We continue to collect a steady stream of data with all eight antineutrino detectors in place,” says Kam-Biu Luk, co-spokesperson for the Daya Bay experiment and senior scientist in Berkeley Lab’s Physics Division and physics professor at the University of California, Berkeley. “This will allow us to hunt for sterile neutrino in an even larger virgin land in the future.”

    See the full article here.

    A U.S. Department of Energy National Laboratory Operated by the University of California

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  • richardmitnick 3:10 pm on August 21, 2013 Permalink | Reply
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    From Berkeley Lab: “New Results from Daya Bay – Tracking the Disappearance of Ghostlike Neutrinos” 


    Berkeley Lab

    Daya Bay neutrino experiment releases high-precision measurement of subatomic shape shifting and new result on differences among neutrino masses

    August 21, 2013
    Lynn Yarris (510) 486-5375 lcyarris@lbl.gov

    “The international Daya Bay Collaboration has announced new results about the transformations of neutrinos – elusive, ghostlike particles that carry invaluable clues about the makeup of the early universe. The latest findings include the collaboration’s first data on how neutrino oscillation – in which neutrinos mix and change into other “flavors,” or types, as they travel – varies with neutrino energy, allowing the measurement of a key difference in neutrino masses known as mass splitting.

    ‘Understanding the subtle details of neutrino oscillations and other properties of these shape-shifting particles may help resolve some of the deepest mysteries of our universe,’ said Jim Siegrist, Associate Director of Science for High Energy Physics at the U.S. Department of Energy (DOE), the primary funder of U.S. participation in Daya Bay.

    U.S. scientists have played essential roles in planning and running of the Daya Bay experiment, which is aimed at filling in the details of neutrino oscillations and mass hierarchy that will give scientists new ways to test for violations of fundamental symmetries. For example, if scientists detect differences in the way neutrinos and antineutrinos oscillate that are beyond expectations, it would be a sign of charge-parity (CP) violation, one of the necessary conditions that resulted in the predominance of matter over antimatter in the early universe. The new results from the Daya Bay experiment about mass-splitting represent an important step towards understanding how neutrinos relate to the structure of our universe today.

    ‘Mass splitting represents the frequency of neutrino oscillation,’ says Kam-Biu Luk of the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), the Daya Bay Collaboration’s Co-spokesperson, who identified the ideal site for the experiment. ‘Mixing angles, another measure of oscillation, represent the amplitude. Both are crucial for understanding the nature of neutrinos.’ Luk is a senior scientist in Berkeley Lab’s Physics Division and a professor of physics at the University of California (UC) Berkeley.

    The Daya Bay Collaboration, which includes more than 200 scientists from six regions and countries, is led in the U.S. by DOE’s Berkeley Lab and Brookhaven National Laboratory (BNL). The Daya Bay Experiment is located close to the Daya Bay and Ling Ao nuclear power plants in China, 55 kilometers northeast of Hong Kong. The latest results from the Daya Bay Collaboration will be announced at the XVth International Workshop on Neutrino Factories, Super Beams and Beta Beams in Beijing, China.

    li8nes
    The Daya Bay Neutrino Experiment is designed to provide new understanding of neutrino oscillations that can help answer some of the most mysterious questions about the universe. Shown here are the photomultiplier tubes in the Daya Bay detectors. (Photo by Roy Kaltschmidt)

    ‘These new precision measurements are a great indication that our efforts will pay off with a deeper understanding of the structure of matter and the evolution of the universe – including why we have a universe made of matter at all,’ says Steve Kettell, a Senior Scientist at BNL and U.S. Daya Bay Chief Scientist.”

    See the full article here.

    A U.S. Department of Energy National Laboratory Operated by the University of California

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  • richardmitnick 3:34 pm on March 21, 2012 Permalink | Reply
    Tags: , DAYA BAY, , ,   

    From isgtw: “A new kind of neutrino transformation” 

    isgtw

    Linda Vu
    March 21, 2012

    “Neutrinos, the wispy particles that flooded the universe in the earliest moments after the Big Bang, are continually produced in the hearts of stars and other nuclear reactions. Untouched by electromagnetism, they respond only to the weak nuclear force and even weaker gravity, passing mostly unhindered through everything from planets to people.

    Years ago scientists also discovered another hidden talent of neutrinos. Although they come in three basic “flavors”—electron, muon and tau—neutrinos and their corresponding antineutrinos can transform from one flavor to another while they are traveling close to the speed of light. How they do this has been a long standing mystery.

    But some new, and unprecedentedly precise, measurements from the multinational Daya Bay Neutrino Experiment are revealing how electron antineutrinos “oscillate” into different flavors as they travel. This new finding from Daya Bay opens a gateway to a new understanding of fundamental physics and may eventually solve the riddle of why there is far more ordinary matter than antimatter in the universe today.

    The international collaboration of researchers is made possible by advanced networking and computing facilities. In the U.S., the Department of Energy’s high-speed science network, ESnet, speeds data to the National Energy Research Scientific Computing Center (NERSC) where it is analyzed, stored and made available to researchers via the Web. Both facilities are located at the DOE’s Lawrence Berkeley National Laboratory (Berkeley Lab).”

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    Daya Bay Neutrino Facility in China. Photo by: Roy Kaltschmidt, Lawrence Berkeley National Laboratory.

    See the full article here.

     
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