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Posts Tagged ‘MicroBooNe’

MicroBooNE sees first cosmic muons

Wednesday, August 12th, 2015

This article appeared in Fermilab Today on Aug. 12, 2015.

This image shows the first cosmic ray event recorded in the MicroBooNE TPC on Aug. 6. Image: MicroBooNE

This image shows the first cosmic ray event recorded in the MicroBooNE TPC on Aug. 6. Image: MicroBooNE

A school bus-sized detector packed with 170 tons of liquid argon has seen its first particle footprints.

On Aug. 6, MicroBooNE, a liquid-argon time projection chamber, or LArTPC, recorded images of the tracks of cosmic muons, particles that shower down on Earth when cosmic rays collide with nuclei in our atmosphere.

“This is the first detector of this size and scale we’ve ever launched in the U.S. for use in a neutrino beam, so it’s a very important milestone for the future of neutrino physics,” said Sam Zeller, co-spokesperson for the MicroBooNE collaboration.

Picking up cosmic muons is just one brief stop during MicroBooNE’s expedition into particle physics. The centerpiece of the three detectors planned for Fermilab’s Short-Baseline Neutrino program, or SBN, MicroBooNE will pursue the much more elusive neutrino, taking data about this weakly interacting particle for about three years. When beam starts up in October, it will travel 470 meters and then traverse the liquid argon in MicroBooNE, where neutrino interactions will result in tracks that the detector can convert into precise three-dimensional images. Scientists will use these images to investigate anomalies seen in an earlier experiment called MiniBooNE, with the aim to determine whether the excess of low-energy events that MiniBooNE saw was due to a new source of background photons or if there could be additional types of neutrinos beyond the three established flavors.

One of MicroBooNE’s goals is to measure how often a neutrino that interacts with an argon atom will produce certain types of particles. A second goal is to conduct R&D for future large-scale LArTPCs. MicroBooNE will carry signals up to two and a half meters across the detector, the longest drift ever for a LArTPC in a neutrino beam. This requires a very high voltage and very pure liquid argon. It is also the first time a detector will operate with its electronics submerged in liquid argon on such a large scale. All of these characteristics will be important for future experiments such as the Deep Underground Neutrino Experiment, or DUNE, which plans to use similar technology to probe neutrinos.

“The entire particle physics community worldwide has identified neutrino physics as one of the key lines of research that could help us understand better how to go beyond what we know now,” said Matt Toups, run coordinator and co-commissioner for MicroBooNE with Fermilab Scientist Bruce Baller. “Those questions that are driving the field, we hope to answer with a very large LArTPC detector.”

Another benefit of the experiment, Zeller said, is training the next generation of LArTPC experts for future programs and experiments. MicroBooNE is a collaborative effort of 25 institutions, with 55 students and postdocs working tirelessly to perfect the technology. Collaborators are keeping their eyes on the road toward the future of neutrino physics and liquid-argon technology.

“It’s been a long haul,” said Bonnie Fleming, MicroBooNE co-spokesperson. “Eight and a half years ago liquid argon was a total underdog. I used to joke that no one would sit next to me at the lunch table. And it’s a world of difference now. The field has chosen liquid argon as its future technology, and all eyes are on us to see if our detector will work.”

Ali Sundermier

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This article appeared in Fermilab Today on Aug. 10, 2015.

The Fermilab Short-Baseline Neutrino program will use three detectors: SBND, MicroBooNE (shown here) and ICARUS. Photo: Reidar Hahn

The Fermilab Short-Baseline Neutrino program will use three detectors: SBND, MicroBooNE (shown here) and ICARUS. Photo: Reidar Hahn

In 1995, physicists working on the Liquid Scintillator Neutrino Detector, or LSND, at Los Alamos National Laboratory stumbled upon some curious results.

The experiment, whose goal was to investigate oscillations between the three different flavors of the elusive neutrino, saw evidence that there might be at least one additional flavor of neutrino lurking just out of reach. In 2002, an experiment at Fermilab called MiniBooNE started collecting data to explore this anomaly, but the results were inconclusive: some data seemed to refute the possibility of a fourth neutrino, but other data seemed to indicate particle interactions that couldn’t be explained with conventional three-neutrino models. The possibility of a mysterious, fourth neutrino remained alive.

“It’s a question that’s been first lingering with the anomalies from LSND and then MiniBooNE,” said Bonnie Fleming, co-spokesperson of a new neutrino experiment at Fermilab called MicroBooNE. “There’s now a worldwide campaign to address whether these short-baseline oscillations and hints from other experiments are indicating new physics.”

Scientists from Fermilab and more than 45 institutions around the world have teamed up to design a program to catch this hypothetical neutrino in the act. The program, called the Short-Baseline Neutrino (SBN) program, makes use of a trio of detectors positioned along one of Fermilab’s neutrino beams. Although there are other reactor and source-based experiments in the world that actively seek a fourth neutrino, also called a sterile neutrino, SBN is the only program that uses a particle accelerator to produce neutrinos and multiple neutrino detectors for this search.

“No one else is doing an experiment like this,” said Peter Wilson, coordinator for the SBN program. “There are no other experiments on this energy scale using the concept of a near detector and a far detector.”

Determining whether there are more than three neutrino flavors would affect how scientists interpret data from experiments like the planned Deep Underground Neutrino Experiment, which is expected to make transformative discoveries about neutrinos, and perhaps other aspects of the universe, in the future. Solving the mystery of the anomalies seen at LSND and MiniBooNE, however, will not be easy. Because the sterile neutrino would not interact through the weak nuclear force as the other three do (hence the name “sterile”), detecting this particle would be like chasing the shadow of a ghost.

It begins at the Fermilab Booster, where protons are accelerated to 8 GeV and smashed into a target, creating new particles. Charged particles are bent forward by a magnetic focusing device into a tunnel where most decay to produce muon neutrinos. The three detectors — named the Short-Baseline Near Detector, or SBND, MicroBooNE and ICARUS — will be spread out over a distance of 600 meters. SBND, 100 meters from the target, will take data close to the source to reduce systematic uncertainties by measuring the initial characteristics of the muon neutrino beam. Four hundred meters beyond the planned site for SBND is MicroBooNE, which is already installed. ICARUS will be located 110 meters past MicroBooNE. ICARUS is an existing detector from a previous experiment at the Italian INFN laboratory at Gran Sasso that is currently being refurbished at CERN. It will have a massive chamber holding 760 tons of liquid argon to beat down statistical uncertainties in the experiment.

All three of the detectors are time projection chambers, a type of detector that allows physicists to analyze particle collisions in three dimensions. For these particular TPCs, scientists use liquid argon because its relatively heavy mass ensures a higher rate of interactions.

MicroBooNE received its last fill of liquid argon in July and recently began taking data. Scientists are expecting to break ground on buildings for both ICARUS and SBND by this fall. In 2017, ICARUS will be fully refurbished and delivered to Fermilab. Scientists hope to complete building SBND that same year.

Since experimenters won’t be able to directly detect the sterile neutrino, they will search for clues in the trails of particles the three known neutrino flavors leave behind in the liquid argon after they interact. If the experiments, expected to begin running in 2018, see deviations in the expected neutrino oscillation pattern, scientists will know that they’re on the right track in their hunt for this fugitive particle. If not, they will be able to put the mystery of the sterile neutrino to rest.

“If we design a strong enough experiment, which I believe we have, then one of two things will happen when we start taking data,” said David Schmitz, co-spokesperson for SBND. “Either we will rule out the earlier hints, or we make, frankly, the most exciting discovery in particle physics in some time.”

Ali Sundermier

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How to make a neutrino beam

Friday, December 12th, 2014

This article appeared in Fermilab Today on Dec. 11, 2014.

Ingredients for a neutrino beam: speedy protons, target, magnetic horn, decay pipe, absorbers. Image adapted from Fermilab

Ingredients for a neutrino beam: speedy protons, target, magnetic horn, decay pipe, absorbers. Image adapted from Fermilab

Fermilab is in the middle of expanding its neutrino program and is developing new detectors to study these ghostly particles. With its exquisite particle accelerator complex, Fermilab is capable of creating very intense beams of neutrinos.

Our neutrino recipe starts with a tank of hydrogen. The hydrogen atoms are fed an extra electron to make them negatively charged, allowing them to be accelerated. Once the charged atoms are accelerated, all of the electrons are ripped off, leaving a beam of positive protons. The protons are extracted into either the Booster Neutrino Beamline (BNB) or are further accelerated and extracted into the Neutrino Main Injector beamline (NuMI). Fermilab is the only laboratory with two neutrino beams. Our two beams have different energies, which allows us to study different properties of the neutrinos.

In the BNB, these protons smash into a target to break up the strong bonds of the quarks inside the proton. These collisions are so violent that they produce new quarks from their excess energy. These quarks immediately form together again into lighter composite short-lived particles called pions and kaons.

Since the pions and kaons emerge at different directions and speeds, they need to be herded together. As a bugle tunes your breath into musical notes, a horn of a different type rounds up and focuses the pions and kaons. The BNB horn looks roughly like the bell of a six-foot long bugle. It produces an electric field that in turn generates a funnel-like magnetic field, which directs all of the dispersed pions and kaons of positive electric charge straight ahead. Particles with negative charges get defocused. By switching the direction of the electric field, we can focus the negatively charged particles while defocusing the positive charges.

The focused particles in the BNB beam travel through a 50-meter long tunnel. This is where the magic happens. In this empty tunnel, the pions and kaons decay in flight into neutrinos, electrons and muons. At the end of the decay tunnel is a wall of steel and concrete to stop and absorb any particle that is not a neutrino. Because neutrinos interact so rarely, they easily whiz through the absorbers and on towards the experiments. And that’s the basic formula to make a beam of neutrinos!

A single neutrino beamline can support many experiments because the neutrinos interact too rarely to get “used up.” The BNB feeds neutrinos to MicroBooNE, and most of them go on through to the other side towards the MiniBooNE detector. Similarly, most of those go on through the other side as well and continue traveling to infinity and beyond. Detectors located in this beam measure neutrino oscillations and their interactions.

The NuMI beamline is designed similarly, but uses a different target material, two focusing horns, and a 675-meter decay pipe. The spacing between the two NuMI horns is adjustable, allowing fine-tuning of the neutrino beam energy. The NuMI beamline has higher-energy neutrinos than the BNB and thus studies different properties of neutrino oscillations.

The NuMI beamline feeds neutrinos to the MINERvA experiment and on through to the MINOS near detector. The NuMI beamline then continues about 450 miles through Earth on toward the MINOS far detector in the Soudan mine in Minnesota. By the time the beam reaches the far detector, it is about 20 miles in diameter! By having a near and far detector, we are able to observe neutrino flavor oscillations by measuring how much of the beam is electron neutrino flavor and muon neutrino flavor at each of these two detectors.

The last of the big Fermilab neutrino experiments is NOvA. Its near detector is off to the side of the NuMI beam and measures neutrinos only with a specific range of direction and energy. The NOvA far detector is positioned to measure the neutrinos with the same properties at a greater distance, about 500 miles away in Ash River, Minnesota. By placing the NOvA detectors 3 degrees to the side of the beam’s center, NOvA will get to make more precise oscillation measurements for a range of neutrino energies.

As more experiments are designed with more demanding requirements, Fermilab may expect to see more neutrino beamline R&D and the construction of new beamlines.

Tia Miceli

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Fermilab published a version of this press release on June 24, 2014.

The 30-ton MicroBooNE neutrino detector is gently lowered into the Liquid-Argon Test Facility at Fermilab on Monday, June 23. The detector will become the centerpiece of the MicroBooNE experiment, which will study ghostly particles called neutrinos. Photo: Fermilab

The 30-ton MicroBooNE neutrino detector is gently lowered into the Liquid-Argon Test Facility at Fermilab on Monday, June 23. The detector will become the centerpiece of the MicroBooNE experiment, which will study ghostly particles called neutrinos. Photo: Fermilab

On Monday, June 23, the next phase of neutrino physics at Fermilab fell (gently) into place.

The MicroBooNE detector – a 30-ton, 40-foot-long cylindrical metal tank designed to detect ghostly particles called neutrinos – was carefully transported by truck across the U.S. Department of Energy’s Fermilab site, from an assembly building it was constructed in to the experimental hall three miles away.

The massive detector was then hoisted up with a crane, lowered through the open roof of the building and placed into its permanent home, directly in the path of Fermilab’s beam of neutrinos. There it will become the centerpiece of the MicroBooNE experiment, which will study those elusive particles to crack several big mysteries of the universe.

The MicroBooNE detector has been under construction for nearly two years. The tank contains a 32-foot-long “time projection chamber,” the largest ever built in the United States, equipped with 8,256 delicate gilded wires, which took the MicroBooNE team two months to attach by hand. This machine will allow scientists to further study the properties of neutrinos, particles that may hold the key to understanding many unexplained mysteries of the universe.

“This is a huge day for the MicroBooNE experiment,” said Fermilab’s Regina Rameika, project manager for the MicroBooNE experiment. “We’ve worked hard to create the best scientific instrument that we can. To see it moved into place was a thrill for the entire team.”

The MicroBooNE detector will now be filled with 170 tons of liquid argon, a heavy liquid that will release charged particles when neutrinos interact with it. The detector’s three layers of wires will then capture pictures of these interactions at different points in time and send that information to the experiment’s computers.

Using one of the most sophisticated processing programs ever designed for a neutrino experiment, those computers will sift through the thousands of interactions that will occur every day and create stunning 3-D images of the most interesting ones. The MicroBooNE team will use that data to learn more about how neutrinos change from one type (or “flavor”) to another, and narrow the search for a hypothesized (but as of yet, never observed) fourth type of neutrino.

“The scientific potential of MicroBooNE is really exciting,” said Yale University’s Bonnie Fleming, co-spokesperson for the MicroBooNE experiment. “After a long time spent designing and building the detector, we are thrilled to start taking data later this year.”

MicroBooNE is a cornerstone of Fermilab’s short-baseline neutrino program , which studies neutrinos traveling over shorter distances. (MINOS and NOvA, which send neutrinos through the Earth to Minnesota, are examples of long-baseline experiments.) In its recent report, the Particle Physics Project Prioritization Panel (P5) expressed strong support for the short-baseline neutrino program at Fermilab.

The P5 panel was comprised of members of the high-energy physics community. Their report was commissioned by the High Energy Physics Advisory Panel, which advises both the Department of Energy and the National Science Foundation on funding priorities.

The detector technology used in designing and building MicroBooNE will serve as a prototype for a much larger long-baseline neutrino facility planned for the United States, to be hosted at Fermilab. The P5 report also strongly supports this larger experiment, which will be designed and funded through a global collaboration.

Read the P5 report.

Fermilab is America’s premier national laboratory for particle physics and accelerator research. A U.S. Department of Energy Office of Science laboratory, Fermilab is located near Chicago, Illinois, and operated under contract by the Fermi Research Alliance, LLC. Visit Fermilab’s website at www.fnal.gov and follow us on Twitter at @FermilabToday.

The DOE Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

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Fermilab planning a busy 2012

Tuesday, January 3rd, 2012

This column by Fermilab Director Pier Oddone first appeared in Fermilab Today Jan. 3 .

We have a mountain of exciting work coming our way!

In accelerator operations, we need to give enough neutrinos to MINERvA to complete their low-energy run, enough anti-neutrinos to MiniBooNE to complete their run and enough neutrinos to MINOS to enable their independent neutrino velocity measurement that will follow up on last year’s OPERA results. We need to provide test beams to several technology development projects and overcome setbacks due to an aging infrastructure to deliver beam to the SeaQuest nuclear physics experiment. And we need to do all of this in the first few months of the year before a year-long shutdown starts. During the shutdown, we will modify the accelerator complex for the NOvA era and begin the campaign to double the number of protons from the Booster to deliver simultaneous beams to various experiments.

In parallel with accelerator modifications, we will push forward on many new experiments. The NOvA detector is in full construction mode, and we face challenges in the very large number of detector elements and large mechanical systems. Any project of this scale requires a huge effort to achieve the full promise of its design. We have the resources in our FY2012 budget to make a lot of progress toward MicroBooNE, Mu2e and LBNE. We will continue to work with DOE to advance Muon g-2. All these experiments are at an important stage in their development and need to be firmly established this year.

At the Cosmic Frontier, we will commission and start operation of the Dark Energy Survey at the Blanco Telescope in Chile, where the camera has arrived and is being tested. In the dark matter arena we will commission and operate the 60 kg COUPP detector at Canada’s SNOLAB and continue the run of the CDMS 15 kg detector in the Soudan Mine while carrying out R&D on future projects. We continue to have a major role in the operation of the Pierre Auger cosmic-ray observatory. In addition we should complete the first phase of the Fermilab Holometer, which will study the properties of space-time at the Planck scale.

At the Energy Frontier, we play a major role in the LHC detector operations and analysis. It should be a fabulously exciting year at the LHC as we push on the hints that we already see in the data.

Beyond construction and operation of facilities we continue our R&D efforts on the superconducting RF technology necessary for Project X and other future accelerators. We will be building the Illinois Accelerator Research Center and moving forward to connect our advanced accelerator program with industry and universities. Our rich program on theory, computation and detector technology will continue to support our laboratory and the particle physics community.

If we accomplish all that is ahead of us for 2012, it will be a year to remember and celebrate when we hit New Year’s Day 2013!

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