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

    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.

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    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 10:43 am on June 4, 2014 Permalink | Reply
    Tags: , , Fermilab MiniBooNE, , ,   

    From Symmetry: “MINOS result narrows field for sterile neutrinos” 

    Symmetry

    June 04, 2014
    Andre Salles

    If you’re searching for something that may not exist, and can pass right through matter if it does, then knowing where to look is essential.

    That’s why the search for so-called sterile neutrinos is a process of elimination. Experiments like Fermilab’s MiniBooNE and the Liquid Scintillator Neutrino Detector (LSND) at Los Alamos National Laboratory have published results consistent with the existence of these theoretical particles. But a new result from the long-running MINOS experiment announced this week severely limits the area in which they could be found and casts more doubt on whether they exist at all.

    no
    Photo by Reidar Hahn, Fermilab

    Scientists have observed three types or “flavors” of neutrinos—muon, electron and tau neutrinos—through their interactions with matter. If there are other types, as some scientists have theorized, they do not interact with matter, and the search for them has become one of the hottest and most contentious topics in neutrino physics. MINOS, located at Fermilab with a far detector in northern Minnesota, has been studying neutrinos since 2005, with an eye toward collecting data on neutrino oscillation over long distances.

    MINOS uses a beam of muon neutrinos generated at Fermilab. As that beam travels 500 miles through the earth to Minnesota, those muon neutrinos can change into other flavors.

    MINOS looks at two types of neutrino interactions: neutral current and charged current. Since MINOS can see the neutral current interactions of all three known flavors of neutrino, scientists can tell if fewer of those interactions occur than they should, which would be evidence that the muon neutrinos have changed into a particle that does not interact. In addition, through charged current interactions, MINOS looks specifically at muon neutrino disappearance, which allows for a much more precise measurement of neutrino energies, according to João Coelho of Tufts University.

    “Disappearance with an energy profile not described by the standard three-neutrino model would be evidence for the existence of an additional sterile neutrino,” Coelho says.

    The new MINOS result, announced today at the Neutrino 2014 conference in Boston, excludes a large and previously unexplored region for sterile neutrinos. To directly compare the new results with previous results from LSND and MiniBooNE, MINOS combined its data with previous measurements of electron antineutrinos from the Bugey nuclear reactor in France. The combined result, says Justin Evans of the University of Manchester, “provides a strong constraint on the existence of sterile neutrinos.”

    “The case for sterile neutrinos is still not closed,” Evans says, “but there is now a lot less space left for them to hide.”

    graph
    The vertical axis shows the possible mass regions for the sterile neutrinos. The horizontal axis shows how likely it is that a muon neutrino will turn into a sterile neutrino as it travels. The new MINOS result excludes everything to the right of the black line. The colored areas show limits by previous experiments. Courtesy of: MINOS collaboration

    See the full article here.

    Symmetry is a joint Fermilab/SLAC publication.



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  • richardmitnick 2:58 pm on February 7, 2014 Permalink | Reply
    Tags: , , , Fermilab MiniBooNE   

    From Fermilab- “Frontier Science Result: MINERvA What happens in hydrocarbon stays in hydrocarbon (sometimes)” 


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

    Friday, Feb. 7, 2014
    Carrie McGivern, University of Pittsburgh

    When a neutrino enters the nucleus of an atom, it can interact with the protons and neutrons inside and impart enough energy to create completely new particles. Often a pion (a particle made of a quark and an antiquark) is produced. However, the nucleus is such a dense place that sometimes the pions never make it out of the atom!

    Figuring out how many pions are produced and how many exit the nucleus is very important in the field of neutrino physics because it determines how well the energy of the incoming neutrino can be measured. Experiments such as LBNE will measure how neutrinos oscillate as a function of neutrino energy, but they will need to understand what those pions are doing in order to get the neutrino energies right.

    Particle physicists have been measuring pions and constructing models of how they interact for a long time, but the neutrino interactions that produce these pions and what happens to them as they exit the nucleus is not nearly as well modeled. The interactions felt by the pions on their way out of the nucleus are called final-state interactions, and they are difficult to calculate because there are so many moving parts — all the protons and neutrons in the nucleus. We do have a few models, but it is important to verify them with experimental data from neutrino experiments. When the MiniBooNE measurement of pion production was first released, it was clear that the most complete models of what happens inside the nucleus were not describing the data. MINERvA now has a sample of several thousand events where a pion, proton and muon are produced when a neutrino interacts with a neutron or proton in the detector’s plastic scintillator, which is made of hydrocarbons (see top figure).

    graph
    This shows what an event in the MINERvA detector looks like when a neutrino comes in from the left and interacts with a proton in the detector, creating a pion that goes backwards, in addition to a proton and a muon.

    By studying the energy distribution of the pions that make it out of the nucleus, MINERvA can determine how big an effect the nucleus has on those pions. The better we understand (and then model) that effect, the better the whole field will be able to measure neutrino energies.

    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 4:13 pm on December 11, 2013 Permalink | Reply
    Tags: , , Fermilab MiniBooNE, , , ,   

    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.

    two
    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]
    .

    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 11:01 am on August 22, 2013 Permalink | Reply
    Tags: , , Fermilab MiniBooNE, ,   

    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.

    micro
    Microboone Detector

    mini
    Miniboone

    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.

    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 11:04 am on March 29, 2013 Permalink | Reply
    Tags: , , Fermilab MiniBooNE,   

    From Fermilab- “Frontier Science Result: MiniBooNE Stealthier than a neutrino” 

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

    Friday, March 29, 2013
    Zarko Pavlovic

    “The search for sterile neutrinos has reached a new milestone. After collecting data for the past decade in both neutrino and antineutrino modes, the MiniBooNE experiment reports in a paper accepted for publication in Physical Review Letters an excess of events that suggests there may be additional neutrinos to the known three. MiniBooNE observed a combined excess of these events with 3.8 sigma significance.

    mast

    graph
    MiniBooNE observes excesses of 78.4 ±20.0 (stat) ±20.3 (syst) and 162.0 ±28.1 (stat) ±38.7 (syst) candidate electron neutrino events in antineutrino (top) and neutrino (bottom) modes, respectively. Here they are given as a function of reconstructed neutrino energy. No credit.

    It took 25 years to observe the electron neutrino after it was predicted to exist, so it is not surprising that it could take even longer to observe the proposed sterile partners of neutrinos. A sterile neutrino, unlike the neutrinos of the Standard Model, would not interact through the weak force. The existence of such neutrinos would be a sign of physics beyond the Standard Model.”

    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 12:01 pm on August 16, 2012 Permalink | Reply
    Tags: , , Fermilab MiniBooNE, ,   

    From Fermilab Today: “Special Result of the Week – The search for new physics in Fermilab’s Booster neutrino beamline” 


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

    Thursday, Aug. 16, 2012
    Warren Huelsnitz

    The conventional picture of neutrinos involves three types: the electron neutrino (and antineutrino), the muon (anti)neutrino, and the tau (anti)neutrino. As they zip through matter or space, the three types, or flavors, continually morph into each other in a phenomenon called neutrino oscillation. On the rare occasions that they interact with matter, they do so through the weak nuclear force.

    graph
    In this joint MiniBooNE-SciBooNE analysis, the experiments have excluded the area to the right of the 90 percent confidence level limit curve (blue) as a region where muon antineutrino disappearance may be occurring. This significantly narrows down the oscillation region for sterile neutrinos.

    But there is growing evidence for short-baseline neutrino anomalies that cannot be explained by the conventional picture. These anomalies include both an excess of events observed by Los Alamos National Laboratory’s Liquid Scintillator Neutrino Detector experiment and Fermilab’s MiniBooNE experiment and a deficit of events observed by reactor and radioactive-source experiments. If these anomalies are in fact due to neutrinos changing from one flavor to another, then there must be one or more new kinds of neutrinos. These additional neutrinos may be what are called ‘sterile neutrinos’ because they do not interact by the weak nuclear force.

    The MiniBooNE experiment, operating in Fermilab’s Booster neutrino beamline since 2002, can search for the appearance of electron (anti)neutrinos or the disappearance of muon (anti)neutrinos. MiniBooNE has reported on appearance signals consistent with the Los Alamos LSND experiment. If electron (anti)neutrino appearance in the Booster neutrino beamline is due to oscillations, with a sterile neutrino acting as an intermediary between electron flavor and muon flavor (anti)neutrinos, then observation of the muon (anti)neutrino disappearance would be a smoking-gun signal for the presence of these sterile neutrinos. With some back-of-the-envelope calculations, it can be shown that on the order of 10 percent of the muon (anti)neutrinos, at certain energies, should be transitioning to sterile neutrinos and hence be unobservable.”

    Interested? Read on here.

    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 11:29 am on December 6, 2011 Permalink | Reply
    Tags: , , Fermilab MiniBooNE, ,   

    From Fermilab Today: “MiniBooNE achieves record” 

    “In the early morning hours of Sept. 28, the MiniBooNE experiment surpassed a special milestone. It collected data from 1021 protons on target in anti-neutrino mode. This is significant because for every 1016 protons on target, there are approximately two antineutrino events produced in the detector. Thus, the more protons on target the more antineutrinos produced for analysis. This milestone was delivered by Accelerator Division, and the huge number of protons resulting from stable running over the course of many years. It is equivalent to almost two milligrams of protons accelerated to the speed of light. This is an amazing achievement and reflects the hard work and dedication of AD.

    i2
    A close-up of the interior of the MiniBooNE tank, before it was filled with ultrapure mineral oil.

    This is a lot of data, but we are not done yet. Given the low rate of antineutrino production, we need to collect 1.5 x 1021 protons on target to produce enough data to reach our analysis goal. Adding up all the neutrino, antineutrino and special runs over the last decade, we have a total of 1.8 x 1021 protons on target, which puts us at the extreme edge of the intensity frontier. The MiniBooNE personnel look forward to further running and, with the outstanding help of AD, to continue pushing the limits of the Intensity Frontier.”

    See the full article here.

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


     
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