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  • richardmitnick 4:05 pm on October 28, 2014 Permalink | Reply
    Tags: , CUORE collaboration, , Neutrinos   

    From LBL: “Creating the Coldest Cubic Meter in the Universe” 

    Berkeley Logo

    Berkeley Lab

    October 28, 2014
    Kate Greene 510-486-4404

    In an underground laboratory in Italy, an international team of scientists has created the coldest cubic meter in the universe. The cooled chamber—roughly the size of a vending machine—was chilled to 6 milliKelvin or -273.144 degrees Celsius in preparation for a forthcoming experiment that will study neutrinos, ghostlike particles that could hold the key to the existence of matter around us.

    cube
    Scientist inspect the cryostat of the of the Cryogenic Underground Observatory for Rare Events. Credit: CUORE collaboration

    The collaboration responsible for the record-setting refrigeration is called the Cryogenic Underground Observatory for Rare Events (CUORE), supported jointly by the Istituto Nazionale di Fisica Nucleare (INFN) in Italy, and the Department of Energy’s Office of Science and National Science Foundation in the US. Lawrence Berkeley National Lab (Berkeley Lab) manages the CUORE project in the US. The CUORE collaboration is made of 157 scientists from the U.S., Italy, China, Spain, and France, and is based in the underground Italian facility called Laboratori Nazionali del Gran Sasso (LNGS) of the INFN.

    “We’ve been building this experiment for almost ten years,” says Yury Kolomensky, senior faculty scientist in the Physics Division of Berkeley Lab, professor of physics at UC Berkeley, and U.S. spokesperson for the CUORE collaboration. “This is a tremendous feat of cryogenics. We’ve exceeded our goal of 10 milliKelvin. Nothing in the universe this large has ever been as cold.”

    The chamber, technically called a cryostat, was designed and built in Italy, and maintained the ultra-cold temperature for more than two weeks. An international team of physicists, including students and postdoctoral scholars from Italy and the US, worked for over two years to assemble the cryostat, iron out the kinks, and demonstrate its record-breaking performance. The claim that no other object of similar size and temperature – either natural or man-made – exists in the universe was detailed in a recent paper by Jonathan Ouellet, Berkeley Lab Nuclear Science staff and UC Berkeley graduate student.

    In order to achieve such a low-temperature cryostat, the team used a multi chamber design that looks something like Russian nesting dolls: six chambers in total, each becoming progressively smaller and colder.

    dolls
    An illustration of the cross-section of the cryostat with a human figure for scale. Credit: CUORE collaboration

    The chambers are evacuated, isolating the insides from the room temperature, like in a thermos. The outer chambers are cooled to the temperature of liquid helium with mechanical coolers called pulse tubes – which do not require expensive cryogenic liquids. The innermost chamber is cooled using a process similar to traditional refrigeration in which a fluid evaporates and takes heat along with it. The only fluid that operates at such cold temperatures, however, is liquid helium. The researchers use a mixture of Helium-3 and Helium-4 that continuously circulates in a specialized cryogenic unit called dilution refrigerator, removing any remnant heat energy from the smallest chamber. The CUORE dilution refrigerator, built by Leiden Cryogenics in Netherlands, is one of the most powerful in the world. “It’s a Mack truck of dilution refrigerators,” Kolomensky says.

    The ultimate purpose for the coldest cubic meter in the universe is to house a new ultra-sensitive detector. The goal of CUORE is to observe a hypothesized rare process called neutrinoless double-beta decay. Detection of this process would allow researchers to demonstrate, for the first time, that neutrinos are their own antiparticles, thereby offering a possible explanation for the abundance of matter over anti-matter in our universe —in other words, why the galaxies, stars, and ultimately people exist in the universe at all.

    To detect neutrinoless double-beta decay, the team is using a detector made of 19 independent towers of tellurium dioxide (TeO2) crystals. Fifty-two crystals, each a little smaller than a Rubik’s cube, make up each tower. The team expects that they would be able to see evidence of the rare radioactive process within these cube-shaped crystals because the phenomenon would produce a barely detectable temperature rise, picked up by highly sensitive temperature sensors.

    Berkeley Lab, with Lawrence Livermore National Lab, has supplied roughly half the crystals for the CUORE project. In addition, Berkeley Lab designed and fabricated the highly sensitive temperature sensors – Neutron Transmutation Doped thermistors invented by Eugene Haller, UC Berkeley faculty and senior faculty scientist in the Material Science Division.

    UC postdocs Tom Banks and Tommy O’Donnell, who also have joint appointments with the Nuclear Science Division at Berkeley Lab, led the international team of physicists, engineers, and technicians to assemble over ten thousand parts into towers in nitrogen-filled glove boxes, including and bonding almost 8000 25-micron gold wires to 100-micron sized pads on the temperature sensors and on copper pads connected to detector wiring.

    The last of the 19 towers has recently been completed; all towers are now safely stored underground at LNGS, waiting to occupy the record-breaking vessel. The coldest cubic meter in the known universe is not just the feat of engineering; it will become a premier science instrument next year.

    US-CUORE team was lead by late Prof. Stuart Freedman until his untimely passing in 2012. Other current and former Berkeley Lab members of the CUORE collaboration not previously mentioned include US Contractor Project Manager Sergio Zimmermann (Engineering Division), former US Contractor Project Manager Richard Kadel (Physics Division, retired), staff scientists Jeffrey Beeman (Materials Science Division), Brian Fujikawa (Nuclear Science Division), Sarah Morgan (Engineering), Alan Smith (EH&S), postdocs Raul Hennings-Yeomans (UCB and NSD), Ke Han (NSD, now Yale), and Yuan Mei (NSD), graduate students Alexey Drobizhev and Sachi Wagaarachchi (UCB and NSD), and engineers David Biare, Lucio di Paolo (NSD and LNGS), and Joseph Wallig (Engineering).

    For more information: CUORE collaboration news release here.

    See the full article here.

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

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  • richardmitnick 3:39 pm on October 28, 2014 Permalink | Reply
    Tags: , , Neutrinos   

    From ICECUBE: “Atmospheric neutrino oscillations measured with three years of IceCube data” 

    icecube
    IceCube South Pole Neutrino Observatory

    28 Oct 2014
    Silvia Bravo

    The IceCube Neutrino Observatory at the South Pole continues to contribute new ways to tackle some of the big questions in astrophysics and neutrino physics research. Results on extraterrestrial neutrinos, cosmic-ray anisotropy, dark matter searches and now neutrino oscillations have proven IceCube to be a powerful tool for exploring the unknown universe using high-energy particles produced in Nature.

    Last year, an initial measurement of the neutrino oscillation parameters was a hint that IceCube could become an important detector for studying neutrino oscillations. Today, the IceCube Collaboration has submitted new results to Physical Review Letters that present an improved measurement of the oscillation parameters, via atmospheric muon neutrino disappearance, which is compatible and comparable in precision to those of dedicated oscillation experiments such as MINOS, T2K or Super-Kamiokande.

    graph
    90 % confidence contours of the result in comparison with the ones of the most sensitive experiments. To the sides of the figure, the log-likelihood profiles for individual oscillation parameters are given. Normal mass hierarchy is assumed. Image: IceCube Collaboration

    Super-Kamiokande was the first experiment to claim the discovery of neutrino oscillations in 1998 from observing a deficit of atmospheric muon neutrino interactions in its detector.

    In contrast to the man-made, water-filled vessel of Super-Kamiokande, IceCube uses a natural target material, the glacier ice at the South Pole. This has the advantage of a much larger observation volume and therefore a larger number of events at shorter time scales. A disadvantage is that the optical properties of ice are more complex. The corresponding uncertainties are taken into account in the systematical errors of the IceCube result.

    “Today, both Super-Kamiokande and IceCube use the same “beam,” which is atmospheric neutrinos, but at different energies. And we reach a similar precision for the determination of the measurable oscillation parameters,” says Juan Pablo Yanez, a postdoctoral researcher at DESY and corresponding author of this paper. “But as IceCube keeps taking data and we keep improving our analyses, we might see important improvements in our collaboration results soon,” adds Yanez.

    IceCube records over one hundred thousand atmospheric neutrinos every year, most of them muon neutrinos produced by the interaction of cosmic rays with the atmosphere. DeepCore, a subdetector of the Antarctic neutrino observatory, allows the detection of neutrinos with energies down to 10 GeV.

    According to our understanding of neutrino oscillations, in which neutrinos can change their type on their trip through matter and space, IceCube should see fewer muon neutrinos at energies around 25 GeV and that reach IceCube after crossing the entire Earth. The reason for these missing muon neutrinos is that many oscillate into other flavors that are not seen by the detector or not selected in this analysis.

    IceCube researchers selected muon neutrino candidates with energies between a few GeV and around 50 GeV and coming from the Northern Hemisphere from data taken between May 2011 and April 2014. About 5,200 events were found, much below the 7,000 expected in the non-oscillations scenario.

    The parameters that best describe the IceCube data, and (normal mass hierarchy assumed), show uncertainties still larger than but already comparable to the neutrino-accelerator experiments. Stay tuned for further news about neutrino oscillations in IceCube!

    + Info “Determining neutrino oscillation parameters from atmospheric muon neutrino disappearance with three years of IceCube DeepCore data,” IceCube Collaboration: M.G. Aartsen et al. Submitted to Physical Review Letters, arXiv.org:1410.7227

    See the full article here.

    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.

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  • richardmitnick 4:52 pm on October 23, 2014 Permalink | Reply
    Tags: , , Neutrinos   

    From FNAL: “UV laser calibration system installed in MicroBooNE” 


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

    Thursday, Oct. 23, 2014
    Rich Blaustein

    Fermilab’s MicroBooNE experiment, expected to launch in early 2015, could very well help determine whether a hypothesized fourth neutrino — referred to as a sterile neutrino — would join the three confirmed ones. Anticipating significant, perhaps momentous, findings, Fermilab and outside collaborators are working hard to ready MicroBooNE for take-off.

    In late September, MicroBooNE collaborators installed a new ultraviolet (UV) laser calibration system in MicroBooNE’s liquid-argon detector at Fermilab. Scientists at Switzerland’s University of Bern Laboratory for High Energy Physics, a MicroBooNE collaborator, designed and built the system specifically for the project.

    two
    Antonio Ereditato (left), head of the Laboratory for High Energy Physics at the University of Bern, and scientist Thomas Strauss, also of the University of Bern, work on MicroBooNE’s UV laser calibration system. Photo: Reidar Hahn

    “This is exciting,” said Fermilab’s Sam Zeller, MicroBooNE co-spokesperson. “This is the first time anyone has deployed such a laser system in a liquid-argon detector for a major neutrino experiment.”

    Fermilab’s MiniBooNE experiment (MicroBooNE’s predecessor) and Los Alamos National Laboratory’s Liquid Scintillator Neutrino Detector experiment raised the possibility of a fourth neutrino. However, the two experiments, while producing many cited — and some differing — results, did not have sensitive liquid-argon detectors for charting neutrino activity.

    “We are recreating that same short-beamline environment, but with MicroBooNE, which has a more capable detector,” said University of Bern’s Michele Weber, MicroBooNE physics analysis coordinator. “We now have some means to address this new neutrino question.”

    Because of the high-resolution imaging capability of liquid-argon detectors such as MicroBooNE’s, it is important to ensure and monitor their correct functioning. One of the calibration system’s goals is to check the detector’s electric field and how it transfers deposits of charge, caused by neutrino interactions with the liquid argon, to the detector’s readout wires.

    With the University of Bern’s UV laser calibration system, ultraviolet laser beams, which are reliably straight, are shot through the argon-filled chamber when the neutrino beam is not activated to test whether the detector’s critical components — wiring, electrical field — are operating maximally or are skewing data readings.

    Physicist Antonio Ereditato, who heads the University of Bern laboratory, explains that a normal visible-light laser does not have enough energy to ionize the liquid argon and create tracks similar to those caused by the neutrinos. But a laser using ultraviolet light, which is higher in energy than visible light, can do the job under specific conditions.

    “The system creates ‘artificial’ tracks that mimic the ionization tracks left by particles. In short, this ultraviolet laser system checks, monitors and calibrates the liquid-argon detector,” Ereditato said.

    “That allows us to measure possible image distortions everywhere,” Weber said. Those distortions can then be accounted for in the data.

    The laser calibration system took eight years of R&D studies to develop. The Bern team also tested it on a liquid-argon detector prototype at their lab.

    “I always joke with the Bern team that the calibration system they built is like a Swiss watch,” Zeller said. “The laser itself, like exquisite clockwork, sweeps across the detector. It is absolutely beautiful.”

    Ereditato and Weber are also very happy with the system. They feel the MicroBooNE experiment embodies the international cooperation and goodwill that bodes well for the future of particle physics.

    “This experiment, which we worked so hard on, and Fermilab’s opening their doors and recognizing our work is very satisfying,” Weber said.

    “If there is another neutrino, it could open up an entirely new particle family — so there is some exciting physics possibly around the corner,” Zeller said. “We are ready to get going.”

    See the full article here.

    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.

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  • richardmitnick 1:08 pm on October 22, 2014 Permalink | Reply
    Tags: , , , , Neutrinos, ,   

    From FNAL: “From the Office of Campus Strategy and Readiness – Building the future of Fermilab” 


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

    Wednesday, Oct. 22, 2014
    ro
    Randy Ortgiesen, head of OCSR, wrote this column.

    As Fermilab and the Department of Energy continue to aggressively “make ready the laboratory” for implementing P5’s recommendations, I can’t help reflecting on all that has recently been accomplished to support the lab’s future — both less visible projects and the big stuff. As we continue to build on these accomplishments, it’s worth noting their breadth and how much headway we’ve made.

    The development of the Muon Campus is proceeding at a healthy clip. Notable in its progress is the completion of the MC-1 Building and the cryogenic systems that support the Muon g-2 experiment. The soon-to-launch beamline enclosure construction project and soon-to-follow Mu2e building is also significant. And none of this could operate without the ongoing, complex accelerator work that will provide beam to these experiments.

    Repurposing of the former CDF building for future heavy-assembly production space and offices is well under way, with more visible exterior improvements to begin soon.

    The new remote operations center, ROC West, is open for business. Several experiments already operate from its new location adjacent to the Wilson Hall atrium.

    The Wilson Street entrance security improvements, including a new guardhouse, are also welcome additions to improved site aesthetics and security operations. Plans for a more modern and improved Pine Street entrance are beginning as well.

    The fully funded Science Laboratory Infrastructure project to replace the Master Substation and critical portions of the industrial cooling water system will mitigate the lab’s largest infrastructure vulnerability for current and future lab operations. Construction is scheduled to start in summer 2015.

    The short-baseline neutrino program is expected to start utility and site preparation very soon, with the start of the detector building construction following shortly thereafter. This is an important and significant part of the near-term future of the lab.

    The start of a demolition program for excess older and inefficient facilities is very close. The program will begin with a portion of the trailers at both the CDF and DZero trailer complexes.

    Space reconfiguration in Wilson Hall to house the new Neutrino Division and LBNF project offices is in the final planning stage and will also be starting soon.

    The atrium improvements, with the reception desk, new lighting and more modern furniture create a more welcoming atmosphere.

    And I started the article by mentioning planning for the “big stuff.” The big stuff, as you may know, includes the lab’s highest-priority project in developing a new central campus. This project is called the Center for Integrated Engineering Research, to be located just west of Wilson Hall. It will consolidate engineering resources from across the site to most efficiently plan for, construct and operate the P5 science projects. The highest-priority Technical Campus project, called the Industrial Center Building Addition, is urgently needed to expand production capacity for the equipment required for future science projects. And lastly the Scientific Hostel, or guest house, for which plans are also under way, will complete the Central Campus theme to “eat-sleep-work to drive discovery.”

    See the full article here.

    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.

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  • richardmitnick 9:30 am on October 13, 2014 Permalink | Reply
    Tags: , , Neutrinos   

    From FNAL: “Fermilab hosts international workshop on neutrino beams” 


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

    Monday, Oct. 13, 2014
    Rich Blaustein

    team
    Fermilab recently hosted scientists from all over the world for a workshop on neutrino beams and instrumentation. Photo: Reidar Hahn

    From Sept. 23-26, Fermilab hosted the Ninth International Workshop on Neutrino Beams and Instrumentation (NBI 2014). Fermilab’s Alberto Marchionni, neutrino physicist in the Accelerator Division, and Bob Zwaska, accelerator physicist in the Accelerator Physics Center, co-chaired NBI 2014. Marchionni and Zwaska said the conference was a big success, with discussions chiefly concerning target materials, facility designs with increased neutrino beam power, safety and international cooperation — all with a heavy focus on long-baseline experiments.

    The workshop series was initiated in 1999 when Japanese scientists, who had just started their neutrino beam for the world’s first long-baseline experiment, sought international input. Participants from other countries understood the value of the workshop and supported its continuation.

    “When you start designing a beamline, you present at this gathering,” Marchionni said.

    He provided an example of earlier NBI discussions on Fermilab’s NuMI neutrino beamline informing the subsequent J-PARC (Japan Proton Accelerator Research Complex) neutrino beamline design.

    Zwaska added that the workshop is especially relevant to Fermilab.

    “Whether with neutrino oscillation experiments — the long-baseline ones, the short-baseline ones — or scattering experiments, neutrino experimentation is central to what Fermilab does,” Zwaska said. “The exchange of information at the workshop is the most efficient way to enhance our skills to conduct these experiments and build neutrino beamlines. There is no book for how to make these beams.”

    A good part of NBI 2014 focused on operations, including safety. Zwaska said that, just like other scientific operations, neutrino beam facilities age, and that access, upkeep and repair of critical components of neutrino beamline systems was an important focus at the workshop.

    Participants also discussed the near- and long-term future, in which beamlines will operate at higher power levels and eventually at megawatt intensities, as in the case of the proposed Long-Baseline Neutrino Facility being developed at Fermilab.

    “We are ready to face the challenge in 2015, when we have to go significantly beyond the power we achieved with NuMI this past year of 360 kilowatts,” Marchionni said, referring to recent improvements to the Fermilab accelerator complex. This will be very auspicious for particle physics, he explained, because Fermilab’s NOvA experiment, matched with data from the other neutrino experiments, will begin to address pressing questions about our universe, such as its matter-antimatter imbalance.

    Like previous NBIs, the importance of international cooperation was underscored at the workshop. Marchionni said international cooperation will be even more important for the higher power operations of the future.

    “The neutrino beam is really a part of the physics of the experiment,” Marchionni said. “In part, because of differing viewpoints like those you find at NBIs, you come up with the best solutions in experiments that have international participation. The same is true for the neutrino beam.”

    The next NBI workshop will take place in Japan in 2016.

    See the full article here.

    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.

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  • richardmitnick 12:45 pm on October 9, 2014 Permalink | Reply
    Tags: , , Neutrinos   

    From FNAL: “Physics in a Nutshell – Neutrinos meet liquid argon” 


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

    Thursday, Oct. 9, 2014
    Tia Miceli

    Fermilab’s flagship effort is its neutrino program, which is ramping up to be the strongest in the world. This means creating the world’s best neutrino detectors. To that end, scientists at Fermilab are pursuing one hot technology that is lighting up neutrino physics, detection based on cryogenic liquid argon.

    tube
    Like neon, argon is used to make colorful lighted signs. Particle physicists are now putting argon to a far more exciting use: detecting neutrinos. Image: P Slawinski

    At first, argon seems to be a pretty boring element. As a noble gas, it does not react chemically. Making up one percent of our atmosphere, it is its third most common component, surpassed only by nitrogen and oxygen. But don’t let its mundane properties fool you. When we cool it down to extremely cold temperatures, it turns into a liquid with incredible properties for cutting-edge neutrino detectors.

    For particle physics, perhaps liquid argon’s most important feature is that it acts as both a target and detector for neutrinos, although it isn’t the only material that can be used this way. The Super-Kamiokande experiment in Japan used water stored in a deep-underground tank as large as Wilson Hall to detect neutrinos. Here at Fermilab, the MiniBooNE experiment used a giant sphere of oil that operated much the same way as Super-Kamiokande’s tank.

    sk
    Super-Kamiokande experiment

    mb
    The MiniBooNE experiment records a neutrino event, in this 2002 image from Fermilab. The ring of light, registered by some of more than one thousand light sensors inside the detector, indicates the collision of a muon neutrino with an atomic nuclei. Credit: Fermilab

    But with 40 protons and neutrons, liquid argon is denser than water or oil, so liquid-argon detectors see more neutrino collisions per unit volume than their oil- or water-based predecessors. That means faster measurements and consequently faster discoveries.

    Another advantage of liquid argon is that, when a neutrino interacts with it and subsequently generates charged particles, it produces two separate kinds of signals; oil- or water-based detectors produce only one. One type of signal, unique to liquid argon, results from its ability to record the charged particles’ trajectories.

    Charged particles are created in the liquid argon after a neutrino flies in and collides with an argon nucleus. The charged debris travels through the argon and easily knocks off electrons from the neighboring atoms along its path. The electronic traces in the liquid argon are pushed by an applied electric field toward an array of wires (similar to a guitar’s) on the side of the detector. The wires collect data on the particle trajectories, producing a signal.

    The second signal type is one shared with oil- and water-based detection: a flash of light. When a charged particle bumps into an argon atom’s electron, the electron transitions to a higher energy. As the electron transitions back to its original state, the excess energy is emitted as light.

    It turns out that argon is also relatively cheap. Companies liquefy air and heat it slowly. Since each of air’s components has a unique boiling temperature, they can be separated. The boiled-off argon is moved to a separate chamber where it is again condensed. The commercially available liquid argon that we buy is still not pure enough for our experiments, so once the liquid argon arrives at the lab, we filter out the remaining impurities by a factor of 10,000.

    Using a common and innocuous gas, Fermilab is establishing itself to be the world’s premier neutrino physics research center. Stay tuned to discover what secrets this technology will unlock!

    See the full article here.

    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.

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  • richardmitnick 6:10 pm on October 6, 2014 Permalink | Reply
    Tags: , , Neutrinos   

    From Symmetry: “500-mile neutrino experiment up and running” 

    Symmetry

    October 06, 2014
    Media Contacts:

    Andre Salles, Fermilab Office of Communication, media@fnal.gov, 630-840-3351
    Rhonda Zurn, University of Minnesota, rzurn@umn.edu, 612-626-7959

    Science Contacts:

    Mark Messier, NOvA co-spokesperson, messier@indiana.edu, 812-855-0236
    Gary Feldman, NOvA co-spokesperson, gfeldman@fas.harvard.edu, 617-496-1044
    Peter Shanahan, Fermilab physicist, NOvA experiment, shanahan@fnal.gov, 630-840-8378
    Marvin Marshak, Ash River Laboratory director, University of Minnesota, marshak@umn.edu, 612-624-1312

    With construction completed, the NOvA neutrino experiment has begun its probe into the mysteries of ghostly particles that may hold the key to understanding the universe.

    It’s the most powerful accelerator-based neutrino experiment ever built in the United States, and the longest-distance one in the world. It’s called NOvA, and after nearly five years of construction, scientists are now using the two massive detectors—placed 500 miles apart—to study one of nature’s most elusive subatomic particles.

    Scientists believe that a better understanding of neutrinos, one of the most abundant and difficult-to-study particles, may lead to a clearer picture of the origins of matter and the inner workings of the universe. Using the world’s most powerful beam of neutrinos, generated at the US Department of Energy’s Fermi National Accelerator Laboratory near Chicago, the NOvA experiment can precisely record the telltale traces of those rare instances when one of these ghostly particles interacts with matter.

    Construction on NOvA’s two massive neutrino detectors began in 2009. In September, the Department of Energy officially proclaimed construction of the experiment completed, on schedule and under budget.

    “Congratulations to the NOvA collaboration for successfully completing the construction phase of this important and exciting experiment,” says James Siegrist, DOE associate director of science for high energy physics. “With every neutrino interaction recorded, we learn more about these particles and their role in shaping our universe.”

    NOvA’s particle detectors were both constructed in the path of the neutrino beam sent from Fermilab in Batavia, Illinois, to northern Minnesota. The 300-ton near-detector, installed underground at the laboratory, observes the neutrinos as they embark on their near-light-speed journey through the Earth, with no tunnel needed. The 14,000-ton far-detector—constructed in Ash River, Minnesota, near the Canadian border—spots those neutrinos after their 500-mile trip and allows scientists to analyze how they change over that long distance.

    FNAL NOvA experiment

    For the next six years, Fermilab will send tens of thousands of billions of neutrinos every second in a beam aimed at both detectors, and scientists expect to catch only a few each day in the far detector, so rarely do neutrinos interact with matter.

    From this data, scientists hope to learn more about how and why neutrinos change between one type and another. The three types, called flavors, are the muon, electron and tau neutrino. Over longer distances, neutrinos can flip between these flavors. NOvA is specifically designed to study muon neutrinos changing into electron neutrinos. Unraveling this mystery may help scientists understand why the universe is composed of matter and why that matter was not annihilated by antimatter after the big bang.

    Scientists will also probe the still-unknown masses of the three types of neutrinos in an attempt to determine which is the heaviest.

    “Neutrino research is one of the cornerstones of Fermilab’s future and an important part of the worldwide particle physics program,” says Fermilab Director Nigel Lockyer. “We’re proud of the NOvA team for completing the construction of this world-class experiment, and we’re looking forward to seeing the first results in 2015.”

    The far detector in Minnesota is believed to be the largest free-standing plastic structure in the world, at 200 feet long, 50 feet high and 50 feet wide. Both detectors are constructed from PVC and filled with a scintillating liquid that gives off light when a neutrino interacts with it. Fiber optic cables transmit that light to a data acquisition system, which creates 3-D pictures of those interactions for scientists to analyze.

    The NOvA far detector in Ash River saw its first long-distance neutrinos in November 2013. The far detector is operated by the University of Minnesota under an agreement with Fermilab, and students at the university were employed to manufacture the component parts of both detectors.

    “Building the NOvA detectors was a wide-ranging effort that involved hundreds of people in several countries,” says Gary Feldman, co-spokesperson of the NOvA experiment. “To see the construction completed and the operations phase beginning is a victory for all of us and a testament to the hard work of the entire collaboration.”

    The NOvA collaboration comprises 208 scientists from 38 institutions in the United States, Brazil, the Czech Republic, Greece, India, Russia and the United Kingdom. The experiment receives funding from the US Department of Energy, the National Science Foundation and other funding agencies.

    See the full article, with video, here.

    Symmetry is a joint Fermilab/SLAC publication.


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  • richardmitnick 2:43 pm on October 3, 2014 Permalink | Reply
    Tags: , , , Neutrinos,   

    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.

    db
    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

    sk
    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: , , Neutrinos   

    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.

    image
    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 2:09 pm on September 5, 2014 Permalink | Reply
    Tags: , , , Neutrinos   

    From FNAL: “Feature – Neutrinos permeate Fermilab’s past, present and future” 


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

    Friday, Sept. 5, 2014
    Troy Rummler

    It was called Target Station C. One of three stations north of Wilson Hall at the end of beamlines extending from the Main Ring (later replaced by the Tevatron), Target Station C was assigned to experiments that would require high beam intensities for investigating neutrino interactions, according to a 1968 design report.

    Fermilab Tevatron
    Tevatron at FNAL

    Within a few years, Target Station C was officially renamed the Neutrino Area. It was the first named fixed-target area and the first to be fully operational. Neutrinos and the Intensity Frontier had an early relationship with Fermilab. But why is it resurfacing now?

    “The experimental program is driven by the current state of knowledge, and that’s always changing,” said Jeffrey Appel, a retired Fermilab physicist and assistant laboratory director who started research at the lab in 1972.

    When Appel first arrived, there was intense interest in neutrinos because the weak force was poorly understood, and neutral currents were still a controversial idea. Fermilab joined forces with many institutions both in and outside the United States, and throughout the 1970s and early 1980s, neutrinos generated from protons in the Main Ring crashed through a 15-foot bubble chamber filled with super-heated liquid hydrogen. Other experiments running in parallel recorded neutrino interactions in iron and scintillator.

    “The goal was to look for the W and Z produced in neutrino interactions,” said Appel. “So the priority for getting the beam up first and the priority for getting the detectors built and installed was on that program in those days.”

    It turns out that the W and Z bosons are too massive to have been produced this way and had to wait to be discovered at colliding-beam experiments. As soon as the Tevatron was ready for colliding beams in 1985, the transition began at Fermilab from fixed-target areas to high-energy particle colliding.

    More recent revelations have shown that neutrinos have mass. These findings have raised new questions that need answers. In 1988, plans were laid to add the Main Injector to the Fermilab campus, partly to boost the capabilities of the Tevatron, but also, according to one report, because “intense beams of neutral kaons and neutrinos would provide a unique facility for CP violation and neutrino oscillation experiments.”

    Although neutrino research was a smaller fraction of the lab’s program during Tevatron operations, it was far from dormant. Two great accomplishments in neutrino research occurred in this time period: One was the most precise neutrino measurement of the strength of the weak interaction by the NuTeV experiment. The other was when the DONUT experiment achieved its goal of making the first direct observation of the tau neutrino in 2000.

    “In the ’90s most evidence of neutrinos changing flavors was coming from natural sources. But this inspired a whole new generation of accelerator-based neutrino experiments,” said Deborah Harris, co-spokesperson for the MINERvA neutrino experiment. “That’s when Fermilab changed gears to make lower-energy but very intense neutrino beams that were uniquely suited for oscillation physics.”

    In partnership with institutions around the globe, Fermilab began planning and building a suite of neutrino experiments. MiniBooNE and MINOS started running in the early 2000s and MINERvA started in 2010. MicroBooNE and NOvA are starting their runs this year.

    Now the lab is working with other institutions to establish a Long-Baseline Neutrino Facility at the laboratory and advance its short-baseline neutrino research program. As Fermilab strengthens its international partnerships in all its neutrino experiments, it is also working to position itself as the home of the world’s forefront neutrino research.

    “The combination of the completion of the Tevatron program and the new questions about neutrinos means that it’s an opportune time to redefine the focus of Fermilab,” Appel explained.

    “Everybody says: ‘It’s not like the old days,’ and it’s always true,” Appel said. “Experiments are bigger and more expensive, but people are just as excited about what they’re doing.”

    He added, “It’s different now but just as exciting, if not more so.”

    See the full article here.

    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.

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