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  • richardmitnick 8:39 am on September 18, 2018 Permalink | Reply
    Tags: , , FNAL MicroBooNE, , , , Super-Kamioka Neutrino Detection Experiment at Kamioka Observatory Tokyo Japan   

    From COSMOS Magazine: “Hints of a fourth type of neutrino create more confusion” 

    Cosmos Magazine bloc

    From COSMOS Magazine

    18 September 2018
    Katie Mack

    Anomalous experimental results hint at the possibility of a fourth kind of neutrino, but more data only makes the situation more confusing.

    Inside the Super-Kamioka Neutrino Detection Experiment at Kamioka Observatory, Tokyo, Japan. Credit: Kamioka Observatory, ICRR (Institute for Cosmic Ray Research), The University of Tokyo

    It was a balmy summer in 1998 when I first became aware of the confounding weirdness of neutrinos. I have vivid memories of that day, as an embarrassingly young student researcher, walking along a river in Japan, listening to a graduate student tell me about her own research project: an attempt to solve a frustrating neutrino–related mystery. We were both visiting a giant detector experiment called Super-Kamiokande, in the heady days right after it released data that forever altered the Standard Model of Particle Physics.

    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.

    Standard Model of Particle Physics from Symmetry Magazine

    What Super-K found was that neutrinos – ghostly, elusive particles that are produced in the hearts of stars and can pass through the whole Earth with only a miniscule chance of interacting with anything – have mass.

    A particle having mass might not sound like a big deal, but the original version of the otherwise fantastically successful Standard Model described neutrinos as massless – just like photons, the particles that carry light and other electromagnetic waves. Unlike photons, however, neutrinos come in three ‘flavours’: electron, muon, and tau.

    Super-K’s discovery was that neutrinos could change from one flavour to another as they travelled, in a process called oscillation. This can only happen if the three flavours have different masses from one another, which means they can’t be massless.

    The finding suggested there must be a fourth neutrino, one invisible in experiments.

    This discovery was a big deal, but it wasn’t the mystery the grad student was working to solve. A few years before, an experiment called the Liquid Scintillator Neutrino Detector (LSND), based in the US, had seen tantalising evidence that neutrinos were oscillating in a way that made no sense at all with the results of other experiments, including Super-K. The LSND finding indirectly suggested there had to be a fourth neutrino in the picture that the other neutrinos were sometimes oscillating into. This fourth neutrino would be invisible in experiments, lacking the kind of interactions that made the others detectable, which gave it the name ‘sterile neutrino’. And it would have to be much more massive than the other three.

    As I learned that day by the river, the result had persisted, unexplained, for years. Most people assumed something had gone wrong with the experiment, but no one knew what.

    In 2007, the plot thickened. An experiment called MiniBooNE, designed primarily to figure out what the heck happened with LSND, didn’t find the distribution of neutrinos it should have seen to confirm the LSND result.


    But some extra neutrinos did show up in MiniBooNE in a different energy range. They were inconsistent with LSND and every other experiment, perhaps suggesting the existence of even more flavours of neutrino.

    Meanwhile, experiments looking at neutrinos produced by nuclear reactors were seeing numbers that also couldn’t easily be explained without a sterile neutrino, though some physicists wrote these off as possibly due to calibration errors.

    And now the plot has grown even thicker.

    In May, MiniBooNE announced new results that seem more consistent with LSND, but even less palatable in the context of other experiments. MiniBooNE works by creating a beam of muon neutrinos and shooting them through the dirt at an underground detector 450 m away. The detector, meanwhile, is monitoring the arrival of electron neutrinos, in case any muon neutrinos are shape-shifting. More of these electron neutrinos turn up than standard neutrino models predict, which implies that some muon neutrinos transform by oscillating into sterile neutrinos too. (Technically, all neutrinos would be swapping around with all others, but this beam only makes sense if there’s an extra, massive one in the mix.)

    But there are several reasons this explanation is facing resistance. One is that experiments just looking for muon neutrinos disappearing (becoming sterile neutrinos or anything else) don’t find a consistent picture. Secondly, if sterile neutrinos at the proposed mass exist, they should have been around in the very early universe, and measurements we have from the cosmic microwave background of the number of neutrino types kicking around then strongly suggest it was just the normal three.

    So, as usual, there’s more work to be done. A MiniBooNE follow-up called MicroBooNE is currently taking data and might make the picture clearer, and other experiments are on the way.


    It seems very likely that something strange is happening in the neutrino sector. It just remains to be seen exactly what, and how, over the next 20 years of constant neutrino bombardment, it will change our understanding of everything else.

    See the full article here .

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  • richardmitnick 2:56 pm on June 22, 2018 Permalink | Reply
    Tags: , FNAL MicroBooNE, , , ,   

    From Scientific American: “Evidence Builds for a New Kind of Neutrino” 

    Scientific American

    From Scientific American

    June 7, 2018
    Clara Moskowitz


    Physicists have caught ghostly particles called neutrinos misbehaving at an Illinois experiment, suggesting an extra species of neutrino exists. If borne out, the findings would be nothing short of revolutionary, introducing a new fundamental particle to the lexicon of physics that might even help explain the mystery of dark matter.

    Undeterred by the fact that no one agrees on what the observations actually mean, experts gathered at a neutrino conference this week in Germany are already excitedly discussing these and other far-reaching implications.

    Neutrinos are confusing to begin with. Formed long ago in the universe’s first moments and today in the hearts of stars and the cores of nuclear reactors, the miniscule particles travel at nearly the speed of light, and scarcely interact with anything else; billions pass harmlessly through your body each day, and a typical neutrino could traverse a layer of lead a light-year thick unscathed. Ever since their discovery in the mid–20th century, neutrinos were predicted to weigh nothing at all, but experiments in the 1990s showed they do have some mass—although physicists still do not know exactly how much. Stranger still, they come in three known varieties, or flavors—electron neutrinos, muon neutrinos and tau neutrinos—and, most bizarrely, can transform from one flavor to another. Because of these oddities and others, many physicists have been betting on neutrinos to open the door to the next frontier in physics.

    Now some think the door has cracked ajar. The discovery comes from 15 years’ worth of data gathered by the Mini Booster Neutrino Experiment (MiniBooNE) at Fermi National Accelerator Laboratory in Batavia, Ill. MiniBooNE detects and characterizes neutrinos by the flashes of light they occasionally create when they strike atomic nuclei in a giant vat filled with 800 tons of pure mineral oil. Its design is similar to that of an earlier project, the Liquid Scintillator Neutrino Detector (LSND) at Los Alamos National Laboratory in New Mexico. In the 1990s LSND observed a curious anomaly, a greater-than-expected number of electron neutrinos in a beam of particles that started out as muon neutrinos; MiniBooNE has now seen the same thing, in a neutrino beam generated by one of Fermilab’s particle accelerators.

    Because muon neutrinos could not have transformed directly into electron flavor over the short distance of the LSND experiment, theorists at the time proposed that some of the particles were oscillating into a fourth flavor—a “sterile neutrino”—and then turning into electron neutrinos, producing the mysterious excess. Although the possibility was tantalizing, many physicists assumed the findings were a fluke, caused by some mundane error particular to LSND. But now that MiniBooNE has observed the very same pattern, scientists are being forced to reckon with potentially more profound causes for the phenomenon. “Now you have to really say you have two experiments seeing the same physics effect, so there must be something fundamental going on,” says MiniBooNE co-spokesperson Richard Van de Water of Los Alamos. “People can’t ignore this anymore.”

    The MiniBooNE team submitted its findings on May 30 to the preprint server arXiv, and is presenting them this week at the XXVIII International Conference on Neutrino Physics and Astrophysics in Heidelberg, Germany.

    A Fourth Flavor

    Sterile neutrinos are an exciting prospect, but outside experts say it is too early to conclude such particles are behind the observations. “If it is sterile neutrinos, it’d be revolutionary,” says Mark Thomson, a neutrino physicist and chief executive of the U.K.’s Science and Technology Facilities Council who was not part of the research. “But that’s a big ‘if.’”

    This new flavor would be called “sterile” because the particles would not feel any of the forces of nature, save for gravity, which would effectively block off communication with the rest of the particle world. Even so, they would still have mass, potentially making them an attractive explanation for the mysterious “dark matter” that seems to contribute additional mass to galaxies and galaxy clusters. “If there is a sterile neutrino, it’s not just some extra particle hanging out there, but maybe some messenger to the universe’s ‘dark sector,’” Van de Water says. “That’s why this is really exciting.” Yet the sterile neutrinos that might be showing up at MiniBooNE seem to be too light to account for dark matter themselves—rather they might be the first vanguard of a whole group of sterile neutrinos of various masses. “Once there is one [sterile neutrino], it begs the question: How many?” says Kevork Abazajian, a theoretical physicist at the University of California, Irvine. “They could participate in oscillations and be dark matter.”

    The findings are hard to interpret, however, because if neutrinos are transforming into sterile neutrinos in MiniBooNE, then scientists would expect to measure not just the appearance of extra electron neutrinos, but a corresponding disappearance of the muon neutrinos they started out as, balanced like two sides of an equation. Yet MiniBooNE and other experiments do not see such a disappearance. “That’s a problem, but it’s not a huge problem,” says theoretical physicist André de Gouvêa of Fermilab. “The reason this is not slam-dunk evidence against the sterile neutrino hypothesis is that [detecting] disappearance is very hard. You have to know exactly how much you had at the beginning, and that’s a challenge.”

    Another Mystery?

    Or perhaps MiniBooNE has discovered something big, but not sterile neutrinos. Maybe some other new aspect of the universe is responsible for the unexpected pattern of particles in the experiment’s beam. “Right now people are thinking about whether there are other new phenomena out there that could resolve this ambiguity,” de Gouvêa says. “Maybe the neutrinos have some new force that we haven’t thought about, or maybe the neutrinos decay in some funny way. It kind of feels like we haven’t hit the right hypothesis yet.”

    Unusually, this is one mystery physicists will not have to wait too long to solve. Another experiment at Fermilab called MicroBooNE was designed to follow MiniBooNE and will be able to study the excess more closely.


    One drawback of MiniBooNE is that it cannot be sure the flashes of light it sees are truly coming from neutrinos—it is possible that some unknown process is producing an excess of photons that mimic the neutrino signal. MicroBooNE, which should deliver its first data later this year, can distinguish between neutrino signals and impostors. If the signal turns out to be an excess of ordinary photons, rather than electron neutrinos, then all bets are off. “We don’t know what would do that in terms of physics, but if it is due to photons, we know that this sterile neutrino interpretation is not correct,” de Gouvêa says.

    In addition to MicroBooNE, Fermilab is building two other detectors to sit on the same beam of neutrinos and work in concert to study the neutrino oscillations going on there. Known collectively as the Short-Baseline Neutrino Program, the new system should be up and running by 2020 and could deliver definitive data in the early part of that decade, says Steve Brice, head of Fermilab’s Neutrino Division.

    FNAL Short baseline neutrino detector

    Until then physicists will continue to debate the mysteries of neutrinos—a field that is growing in size and excitement every year. The meeting happening now in Heidelberg, for example, is the largest neutrino conference ever. “It’s been a steady ramp-up over the last decade,” Brice says. “It’s an area that’s hard to study, but it’s proving to be a very fruitful field for physics.”

    See the full article here .


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    Scientific American, the oldest continuously published magazine in the U.S., has been bringing its readers unique insights about developments in science and technology for more than 160 years.

  • richardmitnick 11:02 am on August 7, 2017 Permalink | Reply
    Tags: , , , FNAL MicroBooNE, , ,   

    From BNL: “MicroBooNE Produces Clearest Images of Neutrino Interactions Yet” 

    Brookhaven Lab

    August 7, 2017
    Kelsey Harper

    With updates to its electronics, the state-of-the-art neutrino detector now boasts impressive “signal to noise” sensitivity.

    A 3D reconstruction of various particles, including neutrinos, interacting with the argon atoms inside MicroBooNE’s time projection chamber (TPC). This reconstruction is based off of when and where electrons produced by such interactions hit the plane of wires at one end of the TPC.


    A U.S.-based international collaboration studying “ghost-like” fundamental particles called neutrinos at an experiment known as MicroBooNE has produced the clearest images of neutrino interactions yet. The U.S. Department of Energy’s Brookhaven National Laboratory contributed to the design of this experiment from the beginning, and recently designed novel low-noise “cold electronics” for the detector, which is located at DOE’s Fermi National Accelerator Laboratory (Fermilab).

    A U.S.-based international collaboration studying “ghost-like” fundamental particles called neutrinos at an experiment known as MicroBooNE has produced the clearest images of neutrino interactions yet. The U.S. Department of Energy’s Brookhaven National Laboratory contributed to the design of this experiment from the beginning, and recently designed novel low-noise “cold electronics” for the detector, which is located at DOE’s Fermi National Accelerator Laboratory (Fermilab). With implementation of sophisticated noise-filtering software and updates to the detector hardware, the MicroBooNE collaboration has produced new clean images that make it easier for researchers to spot and study different types of neutrinos. A paper published in the Journal of Instrumentation illustrates the electronic challenges and solutions that led to this advance.

    “These innovations will naturally be included in the next generation of neutrino detector design,” said Brookhaven physicist Xin Qian, the leader of Brookhaven’s MicroBooNE physics group.

    The next generation is a big deal, literally: four 17,000-ton neutrino detectors (compared to MicroBooNE’s “small” 170-ton detector) are planned for a future Deep Underground Neutrino Experiment (DUNE).

    FNAL LBNF/DUNE from FNAL to SURF, Lead, South Dakota, USA

    FNAL DUNE Argon tank at SURF

    Surf-Dune/LBNF Caverns at Sanford

    SURF building in Lead SD USA

    This massive project will attempt to solve some of the biggest mysteries about neutrinos and their role in our universe.

    Tracking elusive particles

    Trillions of neutrinos—abundant yet elusive particles created in the nuclear reactions powering stars—stream from our sun to Earth every second. But because these particles so rarely interact with matter (which is why we don’t feel them passing through us), the detectors built to spot them must be extremely large and sensitive. To study neutrinos, scientists often also turn to more intense and easily understood sources of these particles: nuclear reactors and particle accelerators. The MicroBooNE collaboration studies neutrinos generated by the Booster proton accelerator at Fermilab, and collects detailed images of their interactions with a detector called a liquid-argon time projection chamber (LArTPC).

    MicroBooNE’s time projection chamber—where the neutrino interactions take place—during assembly at Fermilab. The chamber measures ten meters long and two and a half meters high. Photo credit: Fermilab

    Although a ‘time projection chamber’ may sound like something from a Michael Crichton novel, it’s a very real technology that has transformed neutrino physics. It’s one of the few types of detectors that can see most of what happens when a neutrino interacts inside.

    Neutrinos come in three different “flavors”—electron, muon, and tau. As these neutrinos sail through the LArTPC’s school bus-sized tank of argon, kept liquid at a biting -303 degrees Fahrenheit, they occasionally interact with one of the argon atoms. This interaction produces charged and neutral particles, with a charged particle sometimes corresponding to the type of neutrino involved. The charged particles shoot through the bath, kicking electrons off the argon atoms they pass. These electrons get caught in the tank’s strong electric field and zip toward one end, eventually striking an array of wires. Based on the time and placement of each signal generated when an electron strikes a wire, scientists can figure out where the neutrino collision took place and what it looked like, allowing them to determine the type and energy of the neutrino detected.

    Trouble arises, however, when the little currents produced by the kicked-off electrons are muffled by electronic “noise.” Much like static on a radio, noise can drown out the signals of a neutrino collision, making the reconstructed paths blurry and difficult to analyze. According to Jyoti Joshi, a Brookhaven Lab post-doctoral fellow and the leader of the MicroBooNE detector physics working group, the challenge with LArTPC electronics is that “the signal we’re dealing with is so small that we need a very, very sensitive detector to amplify the signal so we can see it. But then, of course, you amplify anything, including noise.”

    Brookhaven Lab physicist Hucheng Chen holding a replica of one of the 50 cold electronics boards installed in MicroBooNE. He is standing next to a mock-up of one of MicroBooNE’s 11 signal feedthroughs—the part of the detector where electronic signals from the cold electronics of the time projection chamber are carried to the warm electronics outside the cryostat.

    To try to minimize noise, MicroBooNE researchers worked with the engineers and scientists at Fermilab and in Brookhaven Lab’s Instrumentation Division who had pioneered the development of “cold electronics” for the experiment. Placing the electronics inside the detector tank reduces noise by shortening the path each signal has to travel before getting amplified. But because the tank is filled with liquid argon, these electronics had to be designed to thrive at temperatures hundreds of degrees below zero, long past the range where conventional electronics, like those in your smartphone, can function.

    The researchers expected the cold electronics installed at MicroBooNE to produce relatively clean signals and a good picture of the neutrino collisions. But “there are always some surprises,” said Mary Bishai, a senior physicist at Brookhaven Lab. “We had all this excess noise, and at the beginning people blamed the newest technology, the cold electronics.”

    After a year of collecting data, the researchers had enough information to pinpoint three sources of excess noise.

    “The noise was nearly all from the conventional electronics outside the argon tank,” said Mike Mooney, a Brookhaven Lab post-doctoral fellow and a key contributor in the effort to identify sources of noise.

    Most of the noise came from the external power supply for the electronics inside the bath, and from small fluctuations in the high voltage that creates the tank’s electric field. The third and least significant source of noise was an unusual burst that appeared only at a certain frequency, but the team has yet to determine where this final source comes from.

    The collaboration initially reduced the excess noise by developing a software program to sift out the desired electron signals. This initial solution allowed them to collect higher-quality data while addressing the actual sources of noise. “We demonstrated that software could remove certain types of noise from the data without losing the very small signals we want to see” said Brian Kirby, the BNL post-doc leading the evaluation of the software fix.

    A comparison of particle interaction signals before and after MicroBooNE researchers removed the excess noise.

    With the software in place, the researchers could make the necessary changes to the detector’s hardware. They tackled the power supply noise by replacing the part that, just like your laptop charger, converts a higher voltage to a stable lower voltage that the cold electronics require. To combat the noise associated with generating the tank’s electric field, the researchers added a filter that would stabilize the high voltage. They eliminated more than eighty percent of the original noise with these hardware changes alone, and reduced it even further by then reapplying the software filters.

    The reconstructed neutrino paths are now sharply clear, like the burst of a small firework that was previously obscured by fog. These clean tracks are absolutely vital as the MicroBooNE team is implementing pattern recognition software to “train” a computer to pick out different types of neutrino collisions.

    “This is a really big deal in terms of pushing the field forward,” says Qian. “The lessons we learned will feed back to the next generation of technology development. For this kind of technology, there’s no way we can do it ‘just right’ the first time. We need to try it and improve it, try it and improve it.”

    The MicroBooNE collaboration will continue doing just that, trying and improving, as it lays the groundwork for DUNE, the biggest neutrino experiment ever attempted.

    Brookhaven’s work on MicroBooNE was funded by the DOE Office of Science (HEP) and the National Science Foundation.

    See the full article here .

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    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.

  • richardmitnick 3:09 pm on June 24, 2017 Permalink | Reply
    Tags: , , , FNAL MicroBooNE, , ,   

    From Symmetry: “World’s biggest neutrino experiment moves one step closer” 

    Symmetry Mag


    Lauren Biron

    Photo by Maximilien Brice, CERN

    The startup of a 25-ton test detector at CERN advances technology for the Deep Underground Neutrino Experiment.

    FNAL LBNF/DUNE from FNAL to SURF, Lead, South Dakota, USA

    FNAL DUNE Argon tank at SURF

    Surf-Dune/LBNF Caverns at Sanford

    SURF building in Lead SD USA

    In a lab at CERN sits a very important box. It covers about three parking spaces and is more than a story tall. Sitting inside is a metal device that tracks energetic cosmic particles.

    CERN Proto DUNE Maximillian Brice

    This is a prototype detector, a stepping-stone on the way to the future Deep Underground Neutrino Experiment (DUNE). On June 21, it recorded its first particle tracks.

    So begins the largest ever test of an extremely precise method for measuring elusive particles called neutrinos, which may hold the key to why our universe looks the way it does and how it came into being.

    A two-phase detector

    The prototype detector is named WA105 3x1x1 (its dimensions in meters) and holds five active tons—3000 liters—of liquid argon. Argon is well suited to interacting with neutrinos then transmitting the subsequent light and electrons for collection. Previous liquid argon neutrino detectors, such as ICARUS and MicroBooNE, detected signals from neutrinos using wires in the liquid argon. But crucially, this new test detector also holds a small amount of gaseous argon, earning it the special status of a two-phase detector.

    INFN Gran Sasso ICARUS, since moved to FNAL



    As particles pass through the detector, they interact with the argon atoms inside. Electrons are stripped off of atoms and drift through the liquid toward an “extraction grid,” which kicks them into the gas. There, large electron multipliers create a cascade of electrons, leading to a stronger signal that scientists can use to reconstruct the particle track in 3D. Previous tests of this method were conducted in small detectors using about 250 active liters of liquid argon.

    “This is the first time anyone will demonstrate this technology at this scale,” says Sebastien Murphy, who led the construction of the detector at CERN.

    The 3x1x1 test detector represents a big jump in size compared to previous experiments, but it’s small compared to the end goal of DUNE, which will hold 40,000 active tons of liquid argon. Scientists say they will take what they learn and apply it (and some of the actual electronic components) to next-generation single- and dual-phase prototypes, called ProtoDUNE.

    The technology used for both types of detectors is a time projection chamber, or TPC. DUNE will stack many large modules snugly together like LEGO blocks to create enormous DUNE detectors, which will catch neutrinos a mile underground at Sanford Underground Research Facility in South Dakota. Overall development for liquid argon TPCs has been going on for close to 40 years, and research and development for the dual-phase for more than a decade. The idea for this particular dual-phase test detector came in 2013.

    “The main goal [with WA105 3x1x1] is to demonstrate that we can amplify charges in liquid argon detectors on the same large scale as we do in standard gaseous TPCs,” Murphy says.

    By studying neutrinos and antineutrinos that travel 800 miles through the Earth from the US Department of Energy’s Fermi National Accelerator Laboratory [FNAL] to the DUNE detectors, scientists aim to discover differences in the behavior of matter and antimatter. This could point the way toward explaining the abundance of matter over antimatter in the universe. The supersensitive detectors will also be able to capture neutrinos from exploding stars (supernovae), unveiling the formation of neutron stars and black holes. In addition, they allow scientists to hunt for a rare phenomenon called proton decay.

    “All the R&D we did for so many years and now want to do with ProtoDUNE is the homework we have to do,” says André Rubbia, the spokesperson for the WA105 3x1x1 experiment and former co-spokesperson for DUNE. “Ultimately, we are all extremely excited by the discovery potential of DUNE itself.”

    One of the first tracks in the prototype detector, caused by a cosmic ray. André Rubbia

    Testing, testing, 3-1-1, check, check

    Making sure a dual-phase detector and its electronics work at cryogenic temperatures of minus 184 degrees Celsius (minus 300 degrees Fahrenheit) on a large scale is the primary duty of the prototype detector—but certainly not its only one. The membrane that surrounds the liquid argon and keeps it from spilling out will also undergo a rigorous test. Special cryogenic cameras look for any hot spots where the liquid argon is predisposed to boiling away and might cause voltage breakdowns near electronics.

    After many months of hard work, the cryogenic team and those working on the CERN neutrino platform have already successfully corrected issues with the cryostat, resulting in a stable level of incredibly pure liquid argon. The liquid argon has to be pristine and its level just below the large electron multipliers so that the electrons from the liquid will make it into the gaseous argon.

    “Adding components to a detector is never trivial, because you’re adding impurities such as water molecules and even dust,” says Laura Manenti, a research associate at the University College London in the UK. “That is why the liquid argon in the 311—and soon to come ProtoDUNEs—has to be recirculated and purified constantly.”

    While ultimately the full-scale DUNE detectors will sit in the most intense neutrino beam in the world, scientists are testing the WA105 3x1x1 components using muons from cosmic rays, high-energy particles arriving from space. These efforts are supported by many groups, including the Department of Energy’s Office of Science.

    The plan is now to run the experiment, gather as much data as possible, and then move on to even bigger territory.

    “The prospect of starting DUNE is very exciting, and we have to deliver the best possible detector,” Rubbia says. “One step at a time, we’re climbing a large mountain. We’re not at the top of Everest yet, but we’re reaching the first chalet.”

    See the full article here .

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    Symmetry is a joint Fermilab/SLAC publication.

  • richardmitnick 2:06 pm on February 16, 2017 Permalink | Reply
    Tags: , FNAL MicroBooNE, LC Collaboration, Pandora tookit   

    From LC Newsline: “Pandora: opening the box for neutrino experiments” 

    Linear Collider Collaboration header
    Linear Collider Collaboration

    16 February 2017
    Barbara Warmbein

    First neutrino event candidates identified by MicoBooNE. The image shows the raw data with some low-level processing and represent the input to the hit finding and particle flow reconstruction (i.e. pattern recognition) phases

    Pattern recognition rules in particle physics. When particles collide, many things happen at the same time and in a very fast sequence within fractions of a second. In order to tell everyday events from rare ones, particle physicists use pattern recognition software to quickly scan and classify pictures from the collisions.

    A software development kit and event reconstruction system called Pandora has been helping detector developers design and run pattern recognition algorithms since 2009. Under the AIDA-2020 project Pandora has been enhanced for use in a new project: the liquid-argon time projection chamber for the MicroBooNE neutrino experiment based at Fermilab in the United States.


    Pandora was originally developed for tracking particles through calorimeters being designed for the ILC and later the Compact Linear Collider (CLIC).


    CLIC Collider annotated

    The toolkit was the first to manage the particle flow challenge set by linear-collider physicists: to track and identify every single particle from a collision throughout the whole detector.

    Pandora uses a multi-algorithm approach to pattern recognition, in which many small algorithms gradually build up a picture of events. Each algorithm specialises in a specific characteristic or event topology. For the MicroBooNE experiment, Pandora now provides a fully automated reconstruction of neutrino and cosmic-ray events in a very different detector environment to that of the linear collider.

    For MicroBooNE, three separate two-dimensional images per event need to be checked by pattern recognition to finally arrive at a three-dimensional representation of the event. This can be tricky, explains John Marshall, one of the Pandora project leaders: “Features are routinely hidden in at least one view when, for example, two tracks lie on top of one another when viewed from a particular angle. Our new algorithms have a sophisticated interplay between 2D and 3D reconstruction, with iterative corrections made to the 2D reconstruction if features do not correspond between the three “views” of the event.” Pandora thus learns from its own algorithms.

    In the end, the neutrino interactions can be seen in amazing detail. “They are intrinsically very complicated and frequently difficult to reconstruct,” says Marshall.

    “The human brain and eye can normally do a very good job at separating the different particles in the images, but sometimes it’s not easy, even for a human!”

    The MicroBooNE detector consists of a time projection chamber filled with liquid argon. When neutrinos generated from a proton beam at Fermilab pass through the dense liquid, they interact with argon nuclei and create an avalanche of secondary particles that ionise electrons in the liquid-argon volume, which then drift to three wire planes at the TPC’s anode. It’s these three planes that deliver the three different two-dimensional images that Pandora helps reconstruct.

    Interesting events are used to develop the toolkit further. “In-Pandora visualisation tools allow relevant clusters to be displayed and colour-coded, markers can be added to indicate feature points, lines added to indicate straight-line fits, etc.” explains John Marshall. “This visual approach greatly aids algorithm development. Once an algorithm has been developed in the context of a few events, testing starts to be scaled-up to large event samples. Pandora provides a lot of internal error checking, so any mistakes in algorithm logic are normally identified and highlighted very quickly.”

    Pattern recognition is likely to become even more important in the future as images of collisions become more and more detailed with improving detector technologies.

    See the full article here .

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    The Linear Collider Collaboration is an organisation that brings the two most likely candidates, the Compact Linear Collider Study (CLIC) and the International Liner Collider (ILC), together under one roof. Headed by former LHC Project Manager Lyn Evans, it strives to coordinate the research and development work that is being done for accelerators and detectors around the world and to take the project linear collider to the next step: a decision that it will be built, and where.

    Some 2000 scientists – particle physicists, accelerator physicists, engineers – are involved in the ILC or in CLIC, and often in both projects. They work on state-of-the-art detector technologies, new acceleration techniques, the civil engineering aspect of building a straight tunnel of at least 30 kilometres in length, a reliable cost estimate and many more aspects that projects of this scale require. The Linear Collider Collaboration ensures that synergies between the two friendly competitors are used to the maximum.

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  • richardmitnick 7:40 am on November 3, 2015 Permalink | Reply
    Tags: , FNAL MicroBooNE,   

    From FNAL: “MicroBooNE sees first accelerator-born neutrinos” 

    FNAL II photo

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

    Nov. 2, 2015
    Chris Patrick

    This display shows a neutrino event candidate in the MicroBooNE detector. Image: MicroBooNE

    Today the MicroBooNE collaboration announced that it has seen its first neutrinos in the experiment’s newly built detector.

    FNAL Microboone
    Microboone Detector

    “It’s nine years since we proposed, designed, built, assembled and commissioned this experiment,” said Bonnie Fleming, MicroBooNE co-spokesperson and a professor of physics at Yale University. “That kind of investment makes seeing first neutrinos incredible.”

    After months of hard work and improvements by the Fermilab Booster team, on Oct. 15, the Fermilab accelerator complex began delivering protons, which are used to make neutrinos, to one of the laboratory’s newest neutrino experiments, MicroBooNE. After the beam was turned on, scientists analyzed the data recorded by MicroBooNE’s particle detector to find evidence of its first neutrino interactions.

    “This was a big team effort,” said Anne Schukraft, Fermilab postdoc working on MicroBooNE. “More than 100 people have been working very hard to make this happen. It’s exciting to see the first neutrinos.”

    MicroBooNE’s detector is a liquid-argon time projection chamber. It resembles a silo lying on its side, but instead of grain, it’s filled with 170 tons of liquid argon.

    Liquid argon is 40 percent denser than water, and hence neutrinos are more likely to interact with it. When an accelerator-born neutrino hits the nucleus of an argon atom in the detector, its collision creates a spray of subatomic particle debris. Tracking these particles allows scientists to reveal the type and properties of the neutrino that produced them.

    Neutrinos have recently received quite a bit of media attention. The 2015 Nobel Prize in physics was awarded for neutrino oscillations, a phenomenon that is of great importance to the field of elementary particle physics. Intense activity is under way worldwide to capture neutrinos and examine their behavior of transforming from one type into another.

    MicroBooNE is an example of a new liquid-argon detector being developed to further probe this phenomenon while reconstructing the particle tracks emerging from neutrino collisions as finely detailed three-dimensional images. Its findings will be relevant for the forthcoming Deep Underground Neutrino Experiment, known as DUNE, which plans to examine neutrino transitions over longer distances and a much broader energy range. Scientists are also using MicroBooNE as an R&D platform for the large DUNE liquid-argon detectors.

    FNAL Dune & LBNF

    “Future neutrino experiments will use this technology,” said Sam Zeller, Fermilab physicist and MicroBooNE co-spokesperson. “We’re learning a lot from this detector. It’s important not just for us, but for the entire neutrino community.”

    In August, MicroBooNE saw its first cosmic ray events, recording the tracks of cosmic ray muons. The recent neutrino sighting brings MicroBooNE researchers much closer to one of their scientific goals, determining whether the excess of low-energy events observed in a previous Fermilab experiment was the footprint of a sterile neutrino or a new type of background.

    Before they can do that, however, MicroBooNE will have to collect data for several years.

    During this time, MicroBooNE will also be the first liquid-argon detector to measure neutrino interactions from a beam of such low energy. At less than 800 MeV (megaelectronvolts), this beam produces the lowest-energy neutrinos yet to be observed with a liquid-argon detector.

    MicroBooNE is part of Fermilab’s Short-Baseline Neutrino program, and scientists will eventually add two more detectors (ICARUS and the Short-Baseline Near Detector) to its neutrino beamline.


    See the full article here .

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

    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.

    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.

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  • richardmitnick 11:19 am on January 7, 2014 Permalink | Reply
    Tags: , , FNAL MicroBooNE, , ,   

    From Fermilab: “MicroBooNE installs time projection chamber inside vessel, prepares for move” 

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

    Tuesday, Jan. 7, 2014
    Sarah Witman

    On Dec. 20, Fermilab collaborators on the MicroBooNE experiment successfully installed the time projection chamber in the experiment’s vessel at the DZero assembly building.

    A crew installed MicroBooNE’s 5-ton time projection chamber in its cryostat last month. Photo: Reidar Hahn

    The completion of this step is a milestone in the experiment’s years-long narrative. Once the detector is moved to the new Liquid-Argon Test Facility, MicroBooNE scientists can begin a new stage of exploration of the behavior of chargeless, subatomic particles called neutrinos.

    Even though neutrinos are all around us, they are not fully understood. One of scientists’ longstanding questions about neutrinos is how one type morphs into another. MicroBooNE aims to address this and other questions and better explain neutrinos’ role in the universe.

    Once MicroBooNE is up and running, experimenters will shoot beams of neutrinos, manufactured at Fermilab, into the 10-meter-long time projection project chamber, which is filled with 89 tons of liquid argon and sits inside a silo-like vessel called a cryostat. When one of the neutrinos hits an argon nucleus, it will release particles, some of which are charged. This interaction, while it happens in the blink of an eye, will take many months to decipher. Thus scientists make sure that the detector “takes pictures” of all that goes on in its dark, cavernous depths.

    As part of that process, the experiment uses a uniform, high-voltage electric field across the cage-like frame of the time projection chamber. This ensures that, when a charged particle is released, it will travel through the liquid argon, stripping electrons off the argon atoms along the way. The electrons in turn are directed along the electric field to the wires that are positioned along one side of the detector.

    These delicate, gilded wires — all 8,256 of them — took MicroBooNE team members about two months to hand-string across the TPC. They “take the pulse” of each charged particle traversing the TPC and send information about its interaction to researchers’ computers.

    This information is translated into pixels, where each pixel represents the wire that recorded the interaction and each line of pixels represents that wire over time (usually a few microseconds, which is fairly long in particle physics). This “projection” of each wire’s activity over a period of time is where the time projection chamber gets its name, explained Jonathan Asaadi, a postdoc from Syracuse University working on the experiment.

    The wires are angled three different ways — vertically, and rotated 60 degrees to the left and right — so that a computer can construct a 3-D image of the interaction.

    MicroBooNE researchers use a computer algorithm — a similar type of algorithm, in fact, used for facial recognition in airport security — to try to interpret these images and find anomalies. Their different shapes and patterns indicate which type of neutrino was involved in the interaction.

    “By looking at interactions in our detector, we can measure the effective rate at which our neutrinos are changing form,” said Fermilab’s Jennifer Raaf, co-construction manager for MicroBooNE. “That tells us something, fundamentally, about physics.”

    Not only this, but MicroBooNE’s experimenters aim to demonstrate the detector technology needed for the proposed Long-Baseline Neutrino Experiment. LBNE’s multi-kiloton detector would be a far more massive, higher-voltage version of MicroBooNE’s.

    The collaboration is now hooking up the TPC’s cables, after which they’ll test the electronics, cover the open end of the TPC with an endcap and weld the whole thing shut. Then the detector is ready for its move to the Liquid-Argon Test Facility.

    “We’ve been assembling the TPC for more than a year now, so it’s a great feeling to finally have it sitting on its resting pads inside the cryostat,” Raaf said. “Hopefully, the next steps will go as smoothly as the insertion did.”

    See the full article here.

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  • richardmitnick 4:13 pm on December 11, 2013 Permalink | Reply
    Tags: , FNAL MicroBooNE, , , , ,   

    From Fermilab: “MicroBooNE, in 3-D” 

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

    Wednesday, Dec. 11, 2013
    Andre Salles

    Imagine your job is to analyze the data coming from Fermilab’s MicroBooNE experiment.

    It wouldn’t be an easy task. MicroBooNE has been designed specifically to follow up on the MiniBooNE experiment, which may have seen hints of a fourth type of neutrino, one that does not interact with matter in the same way as the three types we know about. The big clue to the possible existence of these particles is low-energy electrons.

    But that experiment could not adequately separate the production of electrons from the production of photons, which would not indicate a new particle. MicroBooNE’s detector, an 89-ton active volume liquid-argon time projection chamber, will be able to. To take advantage of this, every neutrino interaction in the chamber will have to be examined to determine if it created an electron or a photon.

    And there will be a lot of interactions to study — the MicroBooNE collaboration expects to see activity in their detector once every 20 seconds, including nearly 150 neutrino interactions each day.

    If all goes to plan, human operators won’t have to worry about any of that. When MicroBooNE switches on next summer, it will sport one of the most sophisticated 3-D reconstruction software programs ever designed for a neutrino experiment.

    According to Wesley Ketchum and Tingjun Yang, two postdocs leading the software development team at Fermilab, MicroBooNE’s computers will be able to accurately reconstruct neutrino interactions and automatically filter the ones that create electrons. The key to accomplishing this lies in the design of the time projection chamber.

    Tingjun Yang (left) and Wesley Ketchum lead the effort to develop new 3-D reconstruction software for the MicroBooNE experiment. Here they stand inside the MicroBooNE time projection chamber. Photo: Reidar Hahn

    The MicroBooNE detector — the largest time projection chamber in the United States — will be filled with heavy liquid argon and placed in the path of the Booster’s neutrino beam. When neutrinos interact with the argon, they create charged particles that ionize the argon atoms. A high-voltage electric field will draw those ionization electrons toward three planes of wires, spaced three millimeters apart. As they pass through, each plane of wires will take a snapshot of the electrons. Taken together, the snapshots will form a full picture of the original particles.

    “Three planes of wires at different angles will provide a picture of the neutrino interaction in 3-D,” Ketchum said. “We only need two, but the third helps us get rid of ambiguity.”

    The software should be able to provide clear pictures of the data scientists are interested in studying.

    See the full article here [Sorry, the usually dependably archive link is not working. Go to the archive for today, Wednesday, Dec. 11, 2013]

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  • richardmitnick 11:01 am on August 22, 2013 Permalink | Reply
    Tags: , FNAL MicroBooNE, , ,   

    From Fermilab: “Tracking particles with LArIAT” 

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

    Thursday, Aug. 22, 2013
    Laura Dattaro

    “A neutrino is a tricky thing: It rarely interacts with other particles, and it doesn’t leave a track as it enters a detector. But a relatively new technology, called a liquid-argon time projection chamber, is helping scientists to understand them. MicroBooNE, the second phase of the Booster Neutrino Experiment, is one example of a LArTPC, and in order to help it do its job, scientists are first building a test detector called LArIAT—essentially a mini MicroBooNE.

    Microboone Detector


    LArIAT—Liquid-Argon TPC In A Test beam—is a small version of MicroBooNE, with a capacity for about three-quarters of a ton of liquid argon instead of MicroBooNE’s 170 tons. Its aim is to study particle tracks to better understand how different types of particles – in particular electrons and photons—interact in liquid argon, and how these interactions appear in the collected data.

    ‘Understanding what a proton track looks like in comparison to a pion track or a kaon track is one of the goals of LArIAT,’ said Jennifer Raaf, a spokesperson for the experiment.”

    See the full article here.

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    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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