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  • richardmitnick 7:11 pm on February 4, 2016 Permalink | Reply
    Tags: , Neutrino mass experiments, Neutrinos,   

    From Symmetry: “Weighing the lightest particle” 

    Symmetry

    02/04/16
    Diana Kwon

    Physicists are using one of the oldest laws of nature to find the mass of the elusive neutrino.

    Neutrinos are everywhere. Every second, 100 trillion of them pass through your body unnoticed, hardly ever interacting. Though exceedingly abundant, they are the lightest particles of matter, and physicists around the world are attempting the difficult challenge of measuring their mass.

    For a long time, physicists thought neutrinos were massless. This belief was overturned by the discovery that neutrinos oscillate between three flavors: electron, muon and tau. This happens because each flavor contains a mixture of three mass types, neutrino-1, neutrino-2 and neutrino-3, which travel at slightly different speeds.

    According to the measurements taken so far, neutrinos must weigh less than 2 electronvolts (a minute fraction of the mass of the tiny electron, which weighs 511,000 electronvolts). A new generation of experiments is attempting to lower this limit—and possibly even identify the actual mass of this elusive particle.

    Where did the energy go?

    Neutrinos were first proposed by the Austrian-born theoretical physicist Wolfgang Pauli to resolve a problem with beta decay. In the process of beta decay, a neutron in an unstable nucleus transforms into a proton while emitting an electron. Something about this process was especially puzzling to scientists. During the decay, some energy seemed to go missing, breaking the well-established law of energy conservation.

    Pauli suggested that the disappearing energy was slipping away in the form of another particle. This particle was later dubbed the neutrino, or “little neutral one,” by the Italian physicist Enrico Fermi.

    Scientists are now applying the principle of energy conservation to direct neutrino mass experiments. By very precisely measuring the energy of electrons released during the decay of unstable atoms, physicists can deduce the mass of neutrinos.

    “The heavier the neutrino is, the less energy is left over to be carried by the electron,” says Boris Kayser, a theoretical physicist at Fermilab. “So there is a maximum energy that an electron can have when a neutrino is emitted.”

    These experiments are considered direct because they rely on fewer assumptions than other neutrino mass investigations. For example, physicists measure mass indirectly by observing neutrinos’ imprints on other visible things such as galaxy clustering.

    Detecting the kinks

    Of the direct neutrino mass experiments, KATRIN, which is based at the Karlsrule Institute for Technology in Germany, is the closest to beginning its search.

    “If everything works as planned, I think we’ll have very beautiful results in 2017,” says Guido Drexlin, a physicist at KIT and co-spokesperson for KATRIN.

    KATRIN plans to measure the energy of the electrons released from the decay of the radioactive isotope tritium. It will do so by using a giant tank tuned to a precise voltage that allows only electrons above a specific energy to pass through to the detector at the other side. Physicists can use this information to plot the rate of decays at any given energy.

    KIT Katrin experiment
    KATRIN

    The mass of a neutrino will cause a disturbance in the shape of this graph [no graph is present]. Each neutrino mass type should create its own kink. KATRIN, with a peak sensitivity of 0.2 electronvolts (a factor 100 better than previous experiments) will look for a “broad kink” that physicists can use to calculate average neutrino mass.

    Another tritium experiment, Project 8, is attempting a completely different method to measure neutrino mass. The experimenters plan to detect the energy of each individual electron ejected from a beta decay by measuring the frequency of its spiraling motion in a magnetic field. Though still in the early stages, it has the potential to go beyond KATRIN’s sensitivity, giving physicists high hopes for its future.

    Project 8 Full setup
    Project 8 Full setup. I am told that “most of the workhorse hardware is at the University of Washington in Seattle”.

    “KATRIN is the furthest along—it will come out with guns blazing,” says Joseph Formaggio, a physicist at MIT and Project 8 co-spokesperson. “But if they see a signal, the first thing people are going to want to know is whether the kink they see is real. And we can come in and do another experiment with a completely different method.”

    Cold capture

    Others are looking for these telltale kinks using a completely different element, holmium, which decays through a process called electron capture. In these events, an electron in an unstable atom combines with a proton, turning it into a neutron while releasing a neutrino.

    Physicists are measuring the very small amount of energy released in this decay by enclosing the holmium source in microscopic detectors that are operated at very low temperatures (typically below minus 459.2 degrees Fahrenheit). Each holmium decay leads to a tiny increase of the detector’s temperature (about 1/1000 degrees Fahrenheit).

    “To lower the limit on the electron neutrino mass, you need a good thermometer that can measure these very small changes of temperature with high precision,” says Loredana Gastaldo, a Heidelberg University physicist and spokesperson for the ECHo experiment.

    There are currently three holmium experiments, ECHo and HOLMES in Europe and NuMECs in the US, which are in various stages of testing their detectors and producing isotopes of holmium.

    The holmium and tritium experiments will help lower the limit on how heavy neutrinos can be, but it may be that none will be able to definitively determine their mass. It will likely require a combination of both direct and indirect neutrino mass experiments to provide scientists with the answers they seek—or, physicists might even find completely unexpected results.

    “Don’t bet on neutrinos,” Formaggio says. “They’re kind of unpredictable.”

    See the full article here .

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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 3:58 pm on January 20, 2016 Permalink | Reply
    Tags: , Antineutrinos, , Neutrinos,   

    From Symmetry: “Is the neutrino its own antiparticle?” 

    Symmetry

    01/20/16
    Signe Brewster

    The mysterious particle could hold the key to why matter won out over antimatter in the early universe.

    Temp 1
    Artwork by Sandbox Studio, Chicago with Ana Kova

    Almost every particle has an antimatter counterpart: a particle with the same mass but opposite charge, among other qualities.

    This seems to be true of neutrinos, tiny particles that are constantly streaming through us. Judging by the particles released when a neutrino interacts with other matter, scientists can tell when they’ve caught a neutrino versus an antineutrino.

    But certain characteristics of neutrinos and antineutrinos make scientists wonder: Are they one and the same? Are neutrinos their own antiparticles?

    This isn’t unheard of. Gluons and even Higgs bosons are thought to be their own antiparticles. But if scientists discover neutrinos are their own antiparticles, it could be a clue as to where they get their tiny masses—and whether they played a part in the existence of our matter-dominated universe.

    Dirac versus Majorana

    The idea of the antiparticle came about in 1928 when British physicist Paul Dirac developed what became known as the Dirac equation. His work sought to explain what happened when electrons moved at close to the speed of light. But his calculations resulted in a strange requirement: that electrons sometimes have negative energy.

    “When Dirac wrote down his equation, that’s when he learned antiparticles exist,” says André de Gouvêa, a theoretical physicist and professor at Northwestern University. “Antiparticles are a consequence of his equation.”

    Physicist Carl Anderson discovered the antimatter partner of the electron that Dirac foresaw in 1932. He called it the positron—a particle like an electron but with a positive charge.

    Dirac predicted that, in addition to having opposite charges, antimatter partners should have opposite handedness as well.

    A particle is considered right-handed if its spin is in the same direction as its motion. It is considered left-handed if its spin is in the opposite direction.

    Dirac’s equation allowed for neutrinos and anti-neutrinos to be different particles, and, as a result, four types of neutrino were possible: left- and right-handed neutrinos and left- and right-handed antineutrinos. But if the neutrinos had no mass, as scientists thought at the time, only left-handed neutrinos and right-handed antineutrinos needed to exist.

    In 1937, Italian physicist Ettore Majorana debuted another theory: Neutrinos and antineutrinos are actually the same thing. The Majorana equation described neutrinos that, if they happened to have mass after all, could turn into antineutrinos and then back into neutrinos again.

    Temp 2
    Artwork by Sandbox Studio, Chicago with Ana Kova

    The matter-antimatter imbalance

    Whether neutrino masses were zero remained a mystery until 1998, when the Super-Kamiokande and SNO experiments found they do indeed have very small masses—an achievement recognized with the 2015 Nobel Prize for Physics.

    Super-Kamiokande Detector
    Super-Kamiokande neutrino detector

    SNOLAB
    SNO detector [under construction]

    Since then, experiments have cropped up across Asia, Europe and North America searching for hints that the neutrino is its own antiparticle.

    The key to finding this evidence is something called lepton number conservation. Scientists consider it a fundamental law of nature that lepton number is conserved, meaning that the number of leptons and anti-leptons involved in an interaction should remain the same before and after the interaction occurs.

    Scientists think that, just after the big bang, the universe should have contained equal amounts of matter and antimatter. The two types of particles should have interacted, gradually canceling one another until nothing but energy was left behind. Somehow, that’s not what happened.

    Finding out that lepton number is not conserved would open up a loophole that would allow for the current imbalance between matter and antimatter. And neutrino interactions could be the place to find that loophole.

    Neutrinoless double-beta decay

    Scientists are looking for lepton number violation in a process called double beta decay, says SLAC theorist Alexander Friedland, who specializes in the study of neutrinos.

    In its common form, double beta decay is a process in which a nucleus decays into a different nucleus and emits two electrons and two antineutrinos. This balances leptonic matter and antimatter both before and after the decay process, so it conserves lepton number.

    If neutrinos are their own antiparticles, it’s possible that the antineutrinos emitted during double beta decay could annihilate one another and disappear, violating lepton number conservation. This is called neutrinoless double beta decay.

    Such a process would favor matter over antimatter, creating an imbalance.

    “Theoretically it would cause a profound revolution in our understanding of where particles get their mass,” Friedland says. “It would also tell us there has to be some new physics at very, very high energy scales—that there is something new in addition to the Standard Model we know and love.”

    Standard Model
    The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    It’s possible that neutrinos and antineutrinos are different, and that there are two neutrino and anti-neutrino states, as called for in Dirac’s equation. The two missing states could be so elusive that physicists have yet to spot them.

    But spotting evidence of neutrinoless double beta decay would be a sign that Majorana had the right idea instead—neutrinos and antineutrinos are the same.

    “These are very difficult experiments,” de Gouvêa says. “They’re similar to dark matter experiments in the sense they have to be done in very quiet environments with very clean detectors and no radioactivity from anything except the nucleus you’re trying to study.”

    Physicists are still evaluating their understanding of the elusive particles.

    “There have been so many surprises coming out of neutrino physics,” says Reina Maruyama, a professor at Yale University associated with the CUORE neutrinoless double beta decay experiment.

    CUORE experiment
    CUORE neutrinoless double beta decay experiment at Gran Sasso in Italy.

    “I think it’s really exciting to think about what we don’t know.”

    See the full article here .

    Please help promote STEM in your local schools.

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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 8:16 pm on January 4, 2016 Permalink | Reply
    Tags: , , Neutrinos, The international community at FNAL   

    From FNAL: “Fermilab’s global reach” 

    FNAL II photo

    Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

    January 4, 2016
    Chris Patrick

    The international diversity of Fermilab’s user community is growing.

    Scientists and engineers from around the globe have flocked to Fermilab for years to use its resources in their pursuit of answers to the universe’s greatest mysteries. Today, Fermilab hosts users from 44 countries, more than ever before.

    In 2015, Fermilab hosted a total of 3,564 users from 498 institutions. About 33 percent of these users hail from institutions outside of the United States. They come to Fermilab from six continents, a true testament to the universality of the language of science.

    “It’s extremely healthy for the lab because it draws in really smart people from all over the world,” said Bill Louis, 2015-16 chair of the Fermilab Users Executive Committee and scientist from Los Alamos National Laboratory. “Having worked here on and off for the last 40 years, I think the present program is more exciting than ever.”

    Most users continue to come from the United States and the United Kingdom. With 118 users from 37 institutions, Italy has the third-greatest number of users at Fermilab. India is a close fourth with 90 users from 19 institutions.

    Temp 3

    Fermilab plans to even more strongly engage the international neutrino science community as it seeks to host the LBNF/DUNE flagship project.

    FNAL Dune & LBNF
    DUNE/LBNF

    “The future of Fermilab is even more global than ever,” said Fermilab Chief Operating Officer Tim Meyer. “We’re working with partners around the world to plan, design and execute experiments that will change science textbooks.”

    DUNE, the proposed Deep Underground Neutrino Experiment, will send neutrinos 800 miles through the earth from Fermilab to detectors in Lead, South Dakota, to learn more about these ghostly particles. With almost 800 collaborators from 145 institutions and 26 countries around the world, DUNE exemplifies the international effort that characterizes Fermilab’s user community and particle physics at large.

    The Large Hadron Collider’s CMS detector at CERN is another example of the international diversity required to make big discoveries.

    CERN LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC at CERN

    CERN CMS Detector
    CERN CMS Event
    CMS and a possible Higgs event at CMS

    The CMS collaboration has 4,300 active members from 42 countries and 182 institutions, including Fermilab.

    “These days experiments are so big, like DUNE and the LHC, that you really need to draw in the whole world to work on them,” Louis said. “You need to bring in the world’s resources, ideas and talent.”

    Scientists from around the world pulling together to learn more about the nature of neutrinos continues an already well-established practice in the particle physics community.

    “The flagship effort in neutrinos builds on a long history of collaboration to launch the international Short Baseline Neutrino program and will culminate with LBNF/DUNE,” Meyer said.

    FNAL SBND
    Short Baseline Neutrino Detector at FNAL

    “Fermilab may do for neutrinos what CERN did for the Higgs!”

    The nations represented in Fermilab’s user community are Argentina, Australia, Belgium, Brazil, Canada, Chile, China, Colombia, Cyprus, Czech Republic, Denmark, Ecuador, Egypt, Finland, France, Germany, Greece, Hungary, India, Ireland, Israel, Italy, Japan, Korea, Lithuania, Madagascar, Mexico, Paraguay, Peru, Poland, Russian Federation, Serbia, Slovakia, Slovenia, South Africa, Spain, Sweden, Taiwan, Thailand, Turkey, Ukraine, United Kingdom and the United States.

    See the full article here .

    Please help promote STEM in your local schools.

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    Fermilab Campus

    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
    collaborate at Fermilab on experiments at the frontiers of discovery.

     
  • richardmitnick 6:44 pm on January 4, 2016 Permalink | Reply
    Tags: , , Neutrinos   

    From FNAL- “Neutrinos: telling the whole story” 

    FNAL II photo

    Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

    January 4, 2016
    Dipak Rimal

    1
    This plot shows the total probability of neutrinos (top) or antineutrinos (bottom) interacting on a plastic scintillator target as a function of energy. Black points are new results from MINERvA and the colored points are the results from earlier experiments. The solid line is the expected value from simulation.

    2
    Jeff Nelson of the College of William and Mary is seen here in the process of making a plane of scintillator for the MINERvA detector. He will present these results in the Jan. 8 Wine and Cheese Seminar.

    Neutrinos are the most abundant yet most elusive massive particles in the universe. They rarely interact with matter and oscillate into different identities over time. In order to understand these ghostly particles in greater detail, understanding and modeling their feeble interaction with various detector materials used in giant detectors is critical. Neutrino oscillation experiments seek to improve and constrain models used in their simulations to match the reality as closely as possible.

    The MINERvA experiment continues to provide measurements relevant to these experiments to help scientists better model these interactions and implement in their simulation.

    FNAL Minerva
    MINERvA experiment

    This week’s Wine and Cheese Seminar at Fermilab features a talk from MINERvA collaboration, presenting its measurement of the total probability that a muon type neutrino (or antineutrino) interacts with the protons and neutrons inside the MINERvA detector via something called charged-current interaction.

    The signature of the charged-current interaction is the neutrino changing into a charged muon (a heavier cousin of electron) by the exchange of a charged W boson. In the process, the neutrino transfers some of its energy and momentum to the recoil proton or neutron. Depending on the energy and momentum transfer, the recoiled particle can experience one of the following processes: It remains intact; becomes what is called an excited state and decays into other particles; or breaks up into individual constituents and coalesces immediately to form other particles. A measurement of the probability of the interaction happening by any of these channels is what is known as the inclusive cross section.

    When only a small amount of energy is transferred from the neutrino to the proton or neutron, the probability for this charged-current interaction is largely independent of the initial neutrino energy. This provides an alternative method to estimate the number of neutrinos per unit area through the detector, referred to by physicists as neutrino flux, as a function of neutrino energy. This method also provides a valuable tool to complement other methods for determining neutrino flux. The new MINERvA measurement employed this method to extract the neutrino flux and used the extracted flux to measure the inclusive scattering cross sections as the function of initial neutrino energy.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Fermilab Campus

    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
    collaborate at Fermilab on experiments at the frontiers of discovery.

     
  • richardmitnick 5:34 pm on December 28, 2015 Permalink | Reply
    Tags: , , Neutrinos   

    From FNAL: “The flux of the matter” 

    FNAL II photo

    Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

    December 21, 2015
    Ben Messerly

    Temp 1
    The top plot shows the new prediction from the MINERvA experiment of the flux of neutrinos that reach the detector. The flux is given in units of neutrinos per square meter per GeV for every 1 million protons that hit the target, which is located 1 kilometer upstream of the detector itself. The bottom plot shows the ratio between the new prediction and what the prediction would have been if we used only the simulation (called GEANT) and did not take into account measurements from other experiments.

    How many neutrinos are in the Main Injector neutrino (NuMI) beam?

    FNAL NUMI Tunnel project
    NuMI tunnel

    We might already well know if creating a beam of neutrinos were as simple as loading them into a sling shot and firing them off one by one. But with such tiny mass and no electric charge, the elusive neutrino can’t be herded into a sling shot.

    Instead, making a neutrino beam is a multistep process. First, like out of a shotgun, a batch of protons is fired toward a target of carbon. From the proton-carbon collision, debris particles such as pions and kaons are ejected and steered straight by magnetic fields. Finally, some of those debris particles decay into neutrinos, to be caught in a detector down the line.

    But simulating the details of this process — how much of what type of debris is created in the proton-carbon collision and might the debris reinteract with the magnetic horns — turns out to be very difficult task. As a result, predictions of the neutrino flux (the number of neutrinos) in the NuMI beam have had high uncertainties. This has been a big problem for NuMI experiments whose results rely on precise flux estimates. Currently, many measurements have an uncertainty that is dominated by imperfect knowledge of the flux. The success of future long-baseline oscillation experiments demands improved flux knowledge.

    At the Dec. 18 wine and cheese seminar, MINERvA presented the results of a massive effort to upgrade its NuMI beam simulation.

    FNAL  MINERvA
    MINERvA

    Leo Aliaga of the College of William and Mary discussed three primary improvements of the new “Gen 2” flux.

    First, the geometry simulation of the NuMI target and focusing horns has been refined, and a simulation of a water later on the magnetic horns (which keeps them from overheating) has been included.

    2
    Leo Aliaga of the College of William and Mary recently gave a talk on how a new simulation upgrade will improve the way we measure flux. Here he stands by the MINERvA detector. Photo: Reidar Hahn

    Second, MINERvA uses as much external data as it can find from experiments that measure what happens when protons or other particles of known energies hit thin targets of the same material that is in the NuMI beamline (carbon and aluminum, for example). Hadron production data is used to correct how much of what type of hadronic “debris” is created in the proton-target collision.

    And third, the whole simulation has been developed into a free and open Package to Predict the Flux (PPFX) to model the neutrino flux not only for MINERvA, but for the other NuMI experiments as well. The techniques of PPFX and MINERvA’s Gen 2 flux can be used for any conventional NuMI-like beam. Flux predictions with reduced error bands were shown for MINERvA, NOvA and MicroBooNE.

    FNAL NOvA experiment
    NOvA

    FNAL MicroBooNE
    MicroBooNE

    See the full article here .

    Please help promote STEM in your local schools.

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    Fermilab Campus

    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
    collaborate at Fermilab on experiments at the frontiers of discovery.

     
  • richardmitnick 6:00 pm on December 21, 2015 Permalink | Reply
    Tags: , Flavio Cavanna, , neutrino scientist, Neutrinos   

    From FNAL: “One minute with Flavio Cavanna, neutrino scientist” 

    FNAL II photo

    Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

    December 21, 2015

    Fermilab Leah Hesla
    Leah Hesla

    2
    Flavio Cavanna is an active member of the global neutrino community. He is a co-coordinator for ProtoDUNE and an experimentalist on both MicroBooNE and LArIAT.

    How long have you been at Fermilab?
    I’ve been a visiting scientist in the Neutrino Division for a year and a half, coming from Yale University, where I hold an adjunct faculty position. But I’ve been coming to Fermilab since 2007, spending essentially every summer here. Before that I visited from time to time. My original institutional home is in Italy at L’Aquila University and INFN.

    What experiments do you work on?
    I’m involved in most of the liquid-argon detectors for neutrino experiments, including LArIAT, MicroBooNE and DUNE.

    FNAL LArIAT II
    LarIAT

    FNAL Microboone
    MicroBooNE

    FNAL Dune & LBNF
    DUNE

    What are your responsibilities for DUNE?
    Just last week I was appointed co-coordinator for ProtoDUNE at CERN. It’s a joint effort between CERN and the international community, most of it based here in the U.S., to build a full scale prototype for the DUNE detector. When it’s built, around mid-2018, it will be the world’s biggest liquid-argon detector — about 800 tons of liquid argon. We just met here at Fermilab to discuss the first part that will be assembled, the cryostat. The schedule to build ProtoDUNE will proceed very quickly, with an every-other-week goal to achieve. It’s a very exciting time. “It’s hard, but it’s doable,” people keep saying. With a comprehensive coordinated effort of the components of the collaboration, which I hope will increase in the near future, we can achieve this ambitious goal.

    What does a typical day for you look like?
    The MicroBooNE detector recently became fully operational, and in this phase of its life it’s like a baby that is learning to walk, and we stay nearby in case of need. So we have two people on shift 24 hours a day, 7 days a week, and I’m just coming from four consecutive overnight shifts. During the shift, while accumulating neutrino data, we monitor the detector to make sure everything goes smoothly. The nicest thing that can happen is that, at the end of the shift, there’s nothing to pass on to the next shifter. A smooth shift.

    The LArIAT experiment takes a good fraction of my daily activity, which I’m so happy about. It became fully functional in April, when we had the first run at the test beam facility. We closed the detector, filled it with argon, and the second after we switched on the high voltage, we started seeing beautiful tracks, intriguing events. Now we want to extract physical results. To have the full picture, you have to put together the thousands of pieces of a complicated puzzle. The most rewarding part of my day is sitting next to our younger colleagues, discussing physics and struggling with the way to maximize the results and minimize the error. I feel this is just what an experimentalist is supposed to do.

    What do you like to do outside the lab?
    I run five miles almost every day. I live on site, so I profit off the flatness of the region — perhaps too flat for my liking — but for running it’s good. Previously I was living in a mountainous area where I skied, and that’s what I hope to do in the next few days. But what I love the most is spending time with my wife and with my son, who’s 12. I help with homework, some of which I’ve forgotten how to do, but it’s a nice way to catch up on the basics and to spend time next to him.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Fermilab Campus

    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
    collaborate at Fermilab on experiments at the frontiers of discovery.

     
  • richardmitnick 2:19 pm on December 18, 2015 Permalink | Reply
    Tags: , , , , , Neutrinos, ,   

    From Symmetry: “CERN and US increase cooperation” 

    Symmetry

    12/18/15
    Sarah Charley

    1
    Eric Bridiers, US Mission

    The United States and the European physics laboratory have formally agreed to partner on continued LHC research, upcoming neutrino research and a future collider.

    Today in a ceremony at CERN, US Ambassador to the United Nations Pamela Hamamoto and CERN Director-General Rolf Heuer signed five formal agreements that will serve as the framework for future US-CERN collaboration.

    These protocols augment the US-CERN cooperation agreement signed in May 2015 in a White House ceremony and confirm the United States’ continued commitment to research at the Large Hadron Collider.

    CERN LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC at CERN

    They also officially expand the US-CERN partnership to include work on a US-based neutrino research program and on the study of a future circular collider at CERN.

    “This is truly a good day for the relationship between CERN and the United States,” says Hamamoto, US permanent representative to the United Nations in Geneva. “By working together across borders and cultures, we challenge our knowledge and push back the frontiers of the unknown.”

    The partnership between the United States and CERN dates back to the 1950s, when American scientist Isidor Rabi served as one of CERN’s founding members.

    “Today’s agreements herald a new era in CERN-US collaboration in particle physics,” Heuer says. “They confirm the US commitment to the LHC project, and for the first time, they set down in black and white European participation through CERN in pioneering neutrino research in the US. They are a significant step towards a fully connected trans-Atlantic research program.”

    Today, the United States is the most represented nation in both the ATLAS and CMS collaborations at the LHC.

    CERN ATLAS New
    ATLAS

    CMS Use this one
    CMS

    Its contributions are sponsored through the US Department of Energy’s Office of Science and the National Science Foundation.

    According to the new protocols, the United States will continue to support the LHC program through participation in the ATLAS, CMS and ALICE experiments.

    CERN ALICE New
    ALICE

    The LHC Accelerator Research Program, an R&D partnership between five US national laboratories, plans to develop powerful new magnets and accelerating cavities for an upgrade to the accelerator called the High-Luminosity LHC, scheduled to begin at the end of this decade.

    In addition, a joint neutrino-research protocol will enable a new type of reciprocal relationship to blossom between CERN and the US.

    “The CERN neutrino platform is an important development for CERN,” says Marzio Nessi, its coordinator. “It embodies CERN’s undertaking to foster and contribute to fundamental research in neutrino physics at particle accelerators worldwide, notably in the US.”

    The agreement will enable scientists and engineers working at CERN to participate in the design and development of technology for the Deep Underground Neutrino Experiment, a Fermilab-hosted experiment that will explore the mystery of neutrino oscillations and neutrino mass.

    FNAL Dune & LBNF
    DUNE

    For the first time, CERN will serve as a platform for scientists participating in a major research program hosted on another continent. CERN will serve as a European base for scientists working the DUNE experiment and on short-baseline neutrino research projects also hosted by the United States.

    Finally, the protocols pave the way beyond the LHC research program. The United States and CERN will collaborate on physics and technology studies aimed at the development of a proposed new circular accelerator, with the aim of reaching seven times higher energies than the LHC.

    The protocols take effect immediately and will be renewed automatically on a five-year basis.

    See the full article here .

    Please help promote STEM in your local schools.

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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 3:28 pm on December 1, 2015 Permalink | Reply
    Tags: , , Neutrinos   

    From IceCube: “A search for cosmic-ray sources with IceCube, the Pierre Auger Observatory, and the Telescope Array” 

    icecube
    IceCube South Pole Neutrino Observatory

    01 Dec 2015
    Sílvia Bravo

    High-energy neutrinos are thought to be excellent cosmic messengers when exploring the extreme universe: they don’t bend in magnetic fields as cosmic rays (CRs) do and they are not absorbed by the radiation background as gamma rays are. However, it turns out that the deviation of some CRs, namely protons, is expected to be only a few degrees at energies above 50 EeV. This opens the possibility for investigating common origins of high-energy neutrinos and CRs.

    In a new study by the IceCube, Pierre Auger, and Telescope Array Collaborations, scientists have looked for correlations between the highest energy neutrino candidates in IceCube and the highest energy CRs in these two cosmic-ray observatories.

    Pierre Augur Observatory
    Pierre Auger

    Telescope Array Collaboration
    Telescope Array Collaboration

    The results, submitted today to the Journal of Cosmology and Astroparticle Physics, have not found any correlation at discovery level. However, potentially interesting results have been found and will continue to be studied in future joint analyses.

    2
    Maps in Equatorial and Galactic coordinates showing the arrival directions of the IceCube cascades (black dots) and tracks (diamonds), as well as those of the UHECRs detected by the Pierre Auger Observatory (magenta stars) and Telescope Array (orange stars). The circles around the showers indicate angular errors. The black diamonds are the HESE tracks while the blue diamonds stand for the tracks from the through-going muon sample. The blue curve indicates the Super-Galactic plane. Image: IceCube, Pierre Auger and Telescope Array Collaborations.

    The IceCube astrophysical neutrino flux is consistent with an isotropic distribution, which suggests that most neutrinos have an extragalactic origin. The intensity of this flux is also found to be close to the so-called Waxman-Bahcall flux, which is the rate assuming that ultra-high-energy CRs (UHECRs) are mainly protons and have a power-law spectrum. In this scenario, primary cosmic rays collide to a significant extent with photons and neutrons within the source environment, resulting in mainly protons escaping from these sources.

    The UHECRs detected by the Pierre Auger Observatory (Auger) and the Telescope Array (TA) that were used in this study have energies above 50 EeV, since at the highest energies cosmic rays are deflected the least. UHECRs produce neutrinos that carry only 3-5% of the original proton energy, i.e., neutrinos that would have energies of at least several hundred PeVs for the CR sample of this work. However, we expect that the sources of these UHECRs will also produce lower energy CRs, which would then produce neutrinos in the energy range—30 TeV to 2 PeV—observed in IceCube. And this is the idea behind this search: to look for a statistical excess of neutrinos in IceCube from the direction of cosmic rays in the Auger and TA and, thus, their sources.

    Not a simple search, but definitely worth trying to study since searches for the most obvious potential CR sources using IceCube neutrinos have not been successful so far. The major challenges of this search are: i) CRs do not precisely point to their sources, and our knowledge of the deviations produced by the galactic magnetic fields is limited; ii) cascade neutrino events—mainly produced by electron and tau neutrinos—in IceCube are characterized by large angular uncertainties; and iii) IceCube neutrino candidates include background muon events due to the interaction of CRs with the Earth’s atmosphere.

    Researchers have used three different analyses to tackle these challenges. They first searched for cross-correlations between the number of CR-neutrino pairs at different angular windows and compared them to expectations for the null hypothesis of an isotropic UHECR flux. Then, they used a stacking likelihood analysis that looked for the combined contribution from different sources. These two searches used both cascade and track neutrino events from the astrophysical neutrino fluxes measured in IceCube (HESE and high-energy throughgoing muons). IceCube track neutrino signatures are produced by charged-current interactions of muon neutrinos and have an angular uncertainty of less than one degree. Finally, they performed a third study, a stacking search using the neutrino sample used for the four-year point-source search in IceCube, which includes track neutrino candidates only.

    The results obtained are all below 3.3 sigma. There is a potentially interesting finding in the analyses performed with the set of high-energy cascades. When compared to an isotropic flux of neutrinos (fixing the positions of the cosmic rays) to consider the effect of anisotropies in the arrival directions of cosmic rays, the significance is 2.4 sigma for the cross-correlation analysis. These results were obtained with relatively few events and the collaborations will update the analyses in the future with additional statistics to follow their evolution.

    + Info: Search for correlations between the arrival directions of IceCube neutrino events and ultrahigh-energy cosmic rays detected by the Pierre Auger Observatory and the Telescope Array, IceCube, Pierre Auger and Telescope Array Collaborations: M.G.Aartsen et al. Submitted to Journal of Cosmology and Astroparticle Physics, arxiv.org/abs/1511.09408

    See the full article here .

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    ICECUBE neutrino detector
    IceCube is a particle detector at the South Pole that records the interactions of a nearly massless sub-atomic particle called the neutrino. IceCube searches for neutrinos from the most violent astrophysical sources: events like exploding stars, gamma ray bursts, and cataclysmic phenomena involving black holes and neutron stars. The IceCube telescope is a powerful tool to search for dark matter, and could reveal the new physical processes associated with the enigmatic origin of the highest energy particles in nature. In addition, exploring the background of neutrinos produced in the atmosphere, IceCube studies the neutrinos themselves; their energies far exceed those produced by accelerator beams. IceCube is the world’s largest neutrino detector, encompassing a cubic kilometer of ice.

     
  • richardmitnick 12:11 pm on November 19, 2015 Permalink | Reply
    Tags: , , , Neutrinos,   

    From Physics: “Synopsis: LHC Data Might Reveal Nature of Neutrinos” 

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    Physics

    November 18, 2015
    Michael Schirber

    1

    As recognized by this year’s Nobel Prize in physics, evidence now points to neutrinos having mass (see 7 October 2015 Focus story). But this opens up new questions about why the neutrino mass is so much smaller than other particle masses. One solution is to assume that the neutrino is a different kind of particle—one that is its own antiparticle. A new theoretical study shows that observations of W boson decays at the Large Hadron Collider (LHC) in Geneva could potentially uncover the antiparticle nature of the neutrino.

    Electrons, protons, and other fermions are Dirac particles, meaning they have a separate antiparticle with the same mass, but opposite charge. Neutrinos could be Dirac particles, but because they have no electric charge, they could also be Majorana particles, for which particle and antiparticle are the same thing. Such Majorana models are attractive because they offer a fairly natural explanation for the extremely small neutrino mass.

    Experiments looking at extremely rare nuclear decays are trying to detect a possible Majorana or Dirac signature of the neutrino. To widen the search, Claudio Dib from Santa María University in Chile and Choong Sun Kim from Yonsei University in Korea propose looking at W boson decays. They considered decays that result in specific combinations of electrons, muons, and neutrinos. These decays have yet to be observed, but they are predicted in theories involving hypothetical sterile neutrinos. Taking into account current limits on the existence of sterile neutrinos, the team predicts that the next runs at the LHC could produce as many as a few thousand of the desired W boson decays. If this count is correct, then physicists should be able to discriminate Majorana from Dirac neutrinos by the shape of the energy spectrum of the outgoing muons.

    This research is published in Physical Review D.

    See the full article here .

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    Physicists are drowning in a flood of research papers in their own fields and coping with an even larger deluge in other areas of physics. How can an active researcher stay informed about the most important developments in physics? Physics highlights a selection of papers from the Physical Review journals. In consultation with expert scientists, the editors choose these papers for their importance and/or intrinsic interest. To highlight these papers, Physics features three kinds of articles: Viewpoints are commentaries written by active researchers, who are asked to explain the results to physicists in other subfields. Focus stories are written by professional science writers in a journalistic style and are intended to be accessible to students and non-experts. Synopses are brief editor-written summaries. Physics provides a much-needed guide to the best in physics, and we welcome your comments (physics@aps.org).

     
  • richardmitnick 1:04 pm on November 17, 2015 Permalink | Reply
    Tags: , , , , Neutrinos   

    From FNAL- “PIP-II: Renewing Fermilab’s accelerator complex” 

    FNAL II photo

    Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

    Nov. 17, 2015
    Ali Sundermier

    1
    The PIP-II accelerator will provide Fermilab with the high-power beams needed to carry out a world-class neutrino program. Image: Fermilab

    Even accelerator complexes can use some good, old-fashioned makeovers every now and then. The Proton Improvement Plan II, or PIP-II, is a proposed project to improve Fermilab’s particle accelerator complex with a major hardware overhaul and a powerful boost in its capabilities.

    “Every forefront research facility has to be continually renewing itself,” said Steve Holmes, project manager for PIP-II. “Yesterday’s performance is not going to be competitive tomorrow. We’ve done a lot with the Fermilab accelerator complex over the years, but eventually you reach a point where you’ve got to retire some of the really old stuff.”

    The headliner for this upgrade is neutrino physics, Holmes said. The next generation of neutrino programs is going to be bigger and more capable than current experiments. With more beam power, Holmes said, the physics reach will be substantial. When PIP-II achieves its design goal, it will deliver the world’s most intense neutrino beam just in time for the Long-Baseline Neutrino Facility to start operations in 2025. The facility will support Fermilab’s flagship research program, the Deep Underground Neutrino Experiment.

    “We want high power to support our neutrino program,” said Paul Derwent, deputy project manager. “That means lots of particles at high energy and frequently. To increase the power, we need to be able to increase the number of particles right from beginning.”

    PIP-II will allow physicists to accelerate more protons and help them achieve higher energy over a shorter distance. The project will involve retiring Fermilab’s 400-MeV copper linac and building a new 800-MeV superconducting radio-frequency linac as well as replacing the beam transport to the Booster. There will also be upgrades to the laboratory’s Booster, Main Injector and Recycler.

    The most ambitious part of the PIP-II upgrade will be the new 800-MeV linear accelerator, which will be built in the infield of the decommissioned Tevatron accelerator and take advantage of significant existing accelerator infrastructure at Fermilab. The location will provide access to existing utilities, while allowing construction to proceed independent of ongoing accelerator operations and retaining possibilities for upgrade paths down the road. The linac design also provides an option for continuous-wave operations, which means delivery of an uninterrupted, rather than pulsed, stream of particles, providing physicists with more beam for other experiments, such as Mu2e.

    A large part of this effort involves an international collaboration with India. The Department of Atomic Energy in India has offered to contribute hardware in exchange for the experience of building high-intensity superconducting radio-frequency proton linacs, which they hope to construct in their own country.

    “I’m excited to have the chance to retire a bunch of accelerators that were old when I started here 30 years ago,” Holmes joked. “But more seriously, what I find most attractive about this project is the opportunity to do something that will improve the performance of the Fermilab accelerator complex in a manner that will allow us to remain at the forefront both of accelerator-based neutrino physics and our other programs for decades.”

    See the full article here .

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    Fermilab Campus

    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
    collaborate at Fermilab on experiments at the frontiers of discovery.

     
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