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  • richardmitnick 11:40 am on May 12, 2020 Permalink | Reply
    Tags: "Why DUNE? Searching for the origin of matter", , FNAL, , ,   

    From Sanford Underground Research Facility: “Why DUNE? Searching for the origin of matter” 

    SURF logo

    From Sanford Underground Research Facility


    Homestake Mining Company

    May 11, 2020
    Erin Lorraine Broberg

    1
    DUNE science goal icon: Origin of matter.Credit: Fermilab

    Why does matter exist? It may seem like a strange question, but according to current models of the early universe, matter shouldn’t exist.

    “According to what we know about the laws of physics, the amount of matter in the universe should be, effectively, zero,” said André de Gouvêa, a theoretical physicist with the DUNE collaboration and professor at Northwestern University.

    In physics, the discrepancy between what we see—a universe filled with galaxies and a planet teeming with life—and what models predict we should see—absolutely nothing—is called the “matter-antimatter asymmetry problem.” The international Deep Underground Neutrino Experiment, or DUNE, hosted by the Department of Energy’s Fermilab and to be built at Fermilab and Sanford Lab, seeks to solve this problem, which has dogged physicists for nearly a century.

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


    The Deep Underground Neutrino Experiment will measure neutrino oscillations by studying a neutrino that will be sent from Fermilab to the DUNE detectors at the Sanford Underground Neutrino Facility. The experiment will use a muon neutrino beam created at Fermilab’s Long-Baseline Neutrino Facility and send it 800 miles/1300 kilometers straight through the earth to South Dakota. By the time the neutrinos arrive in South Dakota, only a small fraction of neutrinos will be detected as muon neutrinos. Most neutrinos will interact as electron and tau neutrinos. Graphic courtesy Fermilab

    A universe-sized problem

    Despite what the models predict, we find ourselves amidst a universe replete with matter. Everything we see around us is made from just a few types of fundamental particles. Combined, they form protons and neutrons which join up with electrons to form atoms, which in turn bind to make molecules, building ever larger.

    But these key ingredients are only half the story.

    In the 1930s, physicists discovered “antiparticles” that mirror the fundamental particles. Identical in nearly every way, except with reversed charge, these equal yet opposite particles are called antimatter. Just like matter particles, antimatter particles could combine to build bigger and bigger units of antimatter—if they ever survived long enough do to so.

    Although matter and antimatter particles are nearly indistinguishable, the two forms do not coexist peacefully. When antimatter comes into contact with regular matter, particles and antiparticles immediately annihilate, leaving leaving pure energy in their wake.

    This complete, mutual annihilation is the impetus of the matter-antimatter asymmetry problem. Our current models dictate that the Big Bang created equal parts matter and antimatter. Within a second, all the matter and antimatter should have met and annihilated, leaving behind a universe with nothing but energy in the form of light.

    2
    Identical in nearly every way, except with reversed charge, these equal yet opposite particles are called antimatter. Graphic courtesy Fermilab

    “The problem is, if we take our favorite model and calculate the evolution of the universe, we get a prediction that is completely off,” de Gouvêa said. “There should not be any matter in the universe we live in today.”

    We know, of course, that this didn’t happen. We live in a matter-dominated universe with swirling galaxies, innumerable stars and at least one life-sustaining planet. Somehow, about one billionth of the total amount of matter created in the Big Bang managed to evade annihilation and fill the universe with the matter we see today. Thus, the matter-antimatter asymmetry problem.

    Physicists believe there is an undiscovered mechanism, hidden in the wrinkles of nature’s laws, that gave matter an initial advantage over antimatter. And for nearly a century, they’ve been trying to pinpoint it.

    A crack in nature’s symmetry

    Because matter and antimatter are mirror images of each other, physicists assumed that the laws of nature applied to both matter particles and antimatter particles in the exact same way. In physics, this type of equality is called a “symmetry.”

    According to this idea, weak and strong forces should bind particles and antiparticles without discrimination. Gravity should pull on antimatter with the same force it exerts on matter. Magnets should attract oppositely charged particles and antiparticles with the same gusto. In fact, an entire universe made of antimatter should look identical to the one we live in today.

    This assumption of a perfect symmetry among the fundamental building blocks of the universe held true until the 1960s, when James Cronin and Val Fitch made the shocking discovery that, in a very specific case, the universe treats matter slightly different than antimatter.

    Their Nobel Prize-winning experiment examined the way that quarks (fundamental particles that make up protons and neutrons) and antiquarks (their corresponding antiparticles) interacted with the weak force. Rather than treating quarks and antiquarks the same way, the weak force favored quarks in an infamous violation of what is called the Charge Parity (CP) symmetry.

    In other words, the universe had revealed a slight preference for matter over antimatter.

    3
    CP violation experiment: In 1963, a beam from BNL’s Alternating Gradient Synchrotron and the pictured detectors salvaged from the Cosmotron were used to prove the violation of conjugation (C) and parity (P) – winning the Nobel Prize in physics for Princeton University physicists James Cronin and Val Fitch. Photo courtesy Brookhaven National Laboratory.

    This discovery stunned the particle physics community. In the decades that followed, researchers continued to make precision measurements of these decays, combing their data for new physics that might be lurking within this phenomenon. Thirty years after Cronin and Fitch’s discovery, Elizabeth Worcester was making such measurements at Fermilab’s Tevatron with the KTeV experiment.

    “In the 1990s, we were studying the same decays in which CP violation was first observed,” said Worcester, who is now a DUNE physcis co-coordinator and physicist at Brookhaven National Laboratory.

    This glitch in the laws of nature specifically caught the attention of physicists studying the imbalance of matter and antimatter in the universe. Was this violation of CP symmetry the mechanism that allowed some matter to escape annihilation after the Big Bang?

    Subsequent experiments combined with more and more sophisticated calculations demonstrated that nature’s unequal treatment of quarks and antiquarks is not quite big enough to account for the gaping discrepancy we see today.

    However, scientists think the existence of CP violation is a major clue.

    “This violation could mean there is something very fundamental about the laws of nature that we are missing,” de Gouvêa said.

    As soon as Cronin and Fitch made their discovery, physicists began to wonder if other fundamental particles broke the same symmetry. Perhaps multiple sources of CP violation, when combined, could explain how so much matter escaped annihilation in the early universe.

    By finding another, even bigger crack in this symmetry, physicists aim to prove that the universe has an overarching preference for matter, making our current universe possible.

    A ghost-like candidate

    If quarks didn’t provide enough CP violation in the early universe, could another category of elementary particles known as neutrinos have provided another way to favor matter over antimatter?

    “If you look at everything that we’ve learned about neutrinos so far, it indicates that CP could be violated in the neutrino sector,” de Gouvêa said. “There is no specific reason to expect it not to be violated.”

    Neutrinos are extremely challenging to work with. Trillions of these particles pass through you each second. Their miniscule mass and neutral charge make them almost impossible to detect. Building an experiment to test whether these ghost-like particles violate the CP symmetry is even more ambitious.

    “The reason we don’t know if neutrinos violate CP symmetry is purely an experimental issue,” said Ryan Patterson, DUNE physics co-coordinator and professor of physics at the California Institute of Technology (Caltech). “Neutrinos could violate CP a lot, but we don’t know yet because the experiments up to this point haven’t been sensitive enough.”

    One peculiar property of neutrinos, however, makes the DUNE experiment possible. As neutrinos speed through the universe just under the speed of light, they alternate between three different types, or flavors. This process is called oscillation.

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    As neutrinos speed through the universe just under the speed of light, they alternate between three different types, or flavors. This process is called oscillation. Graphic courtesy Fermilab

    “In regard to neutrinos, we only have one realistic way of measuring CP violation: it will show itself in the way neutrinos oscillate between flavors,” de Gouvêa said.

    In principle, the measurement is quite simple, according to de Gouvêa.

    “You simply compare a matter process with an antimatter process, and then you ask if they agree,” de Gouvêa said. To measure the CP violation, researchers must compare the oscillations of neutrinos with the oscillations of antineutrinos. If there is a discrepancy in the way they oscillate over a distance, then neutrinos break the symmetry.

    The difficult part of the experiment is that neutrino oscillations occur over hundreds of miles. To measure a deviation or discrepancy, researchers would need… well, they would need to build a long-baseline neutrino facility.

    Are neutrinos the reason we exist?

    The particulars of this universe-sized mystery have guided the design of the aptly named Long-Baseline Neutrino Facility (LBNF), which will house the Deep Underground Neutrino Experiment. Stretching across the Midwest, with infrastructure located at Fermilab in Batavia, Illinois and at Sanford Lab in Lead, South Dakota, the facility allows researchers to measure just how neutrinos and antineutrinos oscillate over long distances.

    It works like this: a particle accelerator will generate intense beams of neutrinos and antineutrinos at Fermilab. The beams will travel 800 miles straight through rock and earth – no tunnel needed – to enormous particle detectors located deep underground at Sanford Underground Research Facility (Sanford Lab), where 4,850 feet of rock overburden shield the detectors from unwanted background signals.

    During their trip through the Earth’s crust—which takes just four milliseconds—the neutrinos and antineutrinos will oscillate, changing from one flavor into another. Conveniently, the distance between Fermilab and Sanford Lab is ideal for this measurement; by the time the particles arrive at Sanford Lab, their oscillations will be at their peak.

    “To get the best measurement, we put the detectors right where we expect the oscillation to be maximal,” Patterson said.

    When the beam reaches Sanford Lab, some of the neutrinos and antineutrinos will collide with argon atoms inside the detectors. These collisions result in unique signals. By measuring and comparing hundreds of these signals, researchers will be able to tell if neutrinos and antineutrinos oscillate in different ways – the sure-tell sign of CP symmetry violation – and if so, by how much.

    “I think what the neutrinos are going to tell us could change our understanding of nature in a very interesting way,” de Gouvêa said.

    So, why DUNE? In a nutshell, it could help scientists answer one of the big unsolved questions in science and give all of us an answer to the reason we—and everything else in the universe—exists.

    That, however, is only part of the story. Stay tuned for part II of our series of stories about the science of DUNE.

    See the full article here .


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    About us.
    The Sanford Underground Research Facility in Lead, South Dakota, advances our understanding of the universe by providing laboratory space deep underground, where sensitive physics experiments can be shielded from cosmic radiation. Researchers at the Sanford Lab explore some of the most challenging questions facing 21st century physics, such as the origin of matter, the nature of dark matter and the properties of neutrinos. The facility also hosts experiments in other disciplines—including geology, biology and engineering.

    The Sanford Lab is located at the former Homestake gold mine, which was a physics landmark long before being converted into a dedicated science facility. Nuclear chemist Ray Davis earned a share of the Nobel Prize for Physics in 2002 for a solar neutrino experiment he installed 4,850 feet underground in the mine.

    Homestake closed in 2003, but the company donated the property to South Dakota in 2006 for use as an underground laboratory. That same year, philanthropist T. Denny Sanford donated $70 million to the project. The South Dakota Legislature also created the South Dakota Science and Technology Authority to operate the lab. The state Legislature has committed more than $40 million in state funds to the project, and South Dakota also obtained a $10 million Community Development Block Grant to help rehabilitate the facility.

    In 2007, after the National Science Foundation named Homestake as the preferred site for a proposed national Deep Underground Science and Engineering Laboratory (DUSEL), the South Dakota Science and Technology Authority (SDSTA) began reopening the former gold mine.

    In December 2010, the National Science Board decided not to fund further design of DUSEL. However, in 2011 the Department of Energy, through the Lawrence Berkeley National Laboratory, agreed to support ongoing science operations at Sanford Lab, while investigating how to use the underground research facility for other longer-term experiments. The SDSTA, which owns Sanford Lab, continues to operate the facility under that agreement with Berkeley Lab.

    The first two major physics experiments at the Sanford Lab are 4,850 feet underground in an area called the Davis Campus, named for the late Ray Davis. The Large Underground Xenon (LUX) experiment is housed in the same cavern excavated for Ray Davis’s experiment in the 1960s.

    LBNL LZ project at SURF, Lead, SD, USA, will replace LUX at SURF

    In October 2013, after an initial run of 80 days, LUX was determined to be the most sensitive detector yet to search for dark matter—a mysterious, yet-to-be-detected substance thought to be the most prevalent matter in the universe. The Majorana Demonstrator experiment, also on the 4850 Level, is searching for a rare phenomenon called “neutrinoless double-beta decay” that could reveal whether subatomic particles called neutrinos can be their own antiparticle. Detection of neutrinoless double-beta decay could help determine why matter prevailed over antimatter. The Majorana Demonstrator experiment is adjacent to the original Davis cavern.

    LUX’s mission was to scour the universe for WIMPs, vetoing all other signatures. It would continue to do just that for another three years before it was decommissioned in 2016.

    In the midst of the excitement over first results, the LUX collaboration was already casting its gaze forward. Planning for a next-generation dark matter experiment at Sanford Lab was already under way. Named LUX-ZEPLIN (LZ), the next-generation experiment would increase the sensitivity of LUX 100 times.

    SLAC physicist Tom Shutt, a previous co-spokesperson for LUX, said one goal of the experiment was to figure out how to build an even larger detector.
    “LZ will be a thousand times more sensitive than the LUX detector,” Shutt said. “It will just begin to see an irreducible background of neutrinos that may ultimately set the limit to our ability to measure dark matter.”
    We celebrate five years of LUX, and look into the steps being taken toward the much larger and far more sensitive experiment.

    Another major experiment, the Long Baseline Neutrino Experiment (LBNE)—a collaboration with Fermi National Accelerator Laboratory (Fermilab) and Sanford Lab, is in the preliminary design stages. The project got a major boost last year when Congress approved and the president signed an Omnibus Appropriations bill that will fund LBNE operations through FY 2014. Called the “next frontier of particle physics,” LBNE will follow neutrinos as they travel 800 miles through the earth, from FermiLab in Batavia, Ill., to Sanford Lab.

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


    LBNE

    U Washington Majorana Demonstrator Experiment at SURF

    The MAJORANA DEMONSTRATOR will contain 40 kg of germanium; up to 30 kg will be enriched to 86% in 76Ge. The DEMONSTRATOR will be deployed deep underground in an ultra-low-background shielded environment in the Sanford Underground Research Facility (SURF) in Lead, SD. The goal of the DEMONSTRATOR is to determine whether a future 1-tonne experiment can achieve a background goal of one count per tonne-year in a 4-keV region of interest around the 76Ge 0νββ Q-value at 2039 keV. MAJORANA plans to collaborate with GERDA for a future tonne-scale 76Ge 0νββ search.

    CASPAR at SURF


    CASPAR is a low-energy particle accelerator that allows researchers to study processes that take place inside collapsing stars.

    The scientists are using space in the Sanford Underground Research Facility (SURF) in Lead, South Dakota, to work on a project called the Compact Accelerator System for Performing Astrophysical Research (CASPAR). CASPAR uses a low-energy particle accelerator that will allow researchers to mimic nuclear fusion reactions in stars. If successful, their findings could help complete our picture of how the elements in our universe are built. “Nuclear astrophysics is about what goes on inside the star, not outside of it,” said Dan Robertson, a Notre Dame assistant research professor of astrophysics working on CASPAR. “It is not observational, but experimental. The idea is to reproduce the stellar environment, to reproduce the reactions within a star.”

     
  • richardmitnick 1:53 pm on May 4, 2020 Permalink | Reply
    Tags: , Data onslaught, FNAL, , ,   

    From Fermi National Accelerator Lab: “DUNE prepares for data onslaught” 

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    FNAL Art Image by Angela Gonzales

    From Fermi National Accelerator Lab , an enduring source of strength for the US contribution to scientific research world wide.

    May 4, 2020
    Jim Daley

    The international Deep Underground Neutrino Experiment, hosted by Fermilab, will be one of the most ambitious attempts ever made at understanding some of the most fundamental questions about our universe.

    LBNF/DUNE

    SURF-Sanford Underground Research Facility, Lead, South Dakota, USA


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


    SURF DUNE LBNF Caverns at Sanford Lab


    FNAL DUNE Argon tank at SURF

    Currently under construction at the Sanford Underground Research Facility in South Dakota, DUNE will provide a massive target for neutrinos. When it’s operational, DUNE will comprise around 70,000 tons of liquid argon — more than enough to fill a dozen Olympic-sized swimming pools — contained in cryogenic tanks nearly a mile underground.

    Neutrinos are ubiquitous. They were formed in the first seconds after the Big Bang, even before atoms could form, and they are constantly being produced by nuclear reactions in stars. When massive stars explode and become supernovae, the vast majority of the energy given off in the blast is released as a burst of neutrinos.

    In the laboratory, scientists use particle accelerators to make neutrinos. In DUNE’s case, Fermilab accelerators will generate the world’s most powerful high-energy neutrino beam, aiming it at the DUNE neutrino detector 800 miles (1,300 kilometers) away in South Dakota.

    When any of these neutrinos — star-born or terrestrial — strikes one of the argon atoms in the DUNE detector, a cascade of particles results. Every time this happens, billions of detector digits are generated, which must be saved and analyzed further by collaborators over the world. The resulting data that will be churned out by the detector will be immense. So, while construction continues in South Dakota, scientists around the world are hard at work developing the computing infrastructure necessary to handle the massive volumes of data the experiment will produce.

    3
    The goal of the DUNE Computing Consortium is to establish a global computing network that can handle the massive data dumps DUNE will produce by distributing them across the grid. Photo: Reidar Hahn, Fermilab

    The first step is ensuring that DUNE is connected to Fermilab with the kind of bandwidth that can carry tens of gigabits of data per second, said Liz Sexton-Kennedy, Fermilab’s chief information officer. As with other aspects of the collaboration, it requires “a well-integrated partnership,” she said. Each neutrino collision in the detector will produce an array of information to be analyzed.

    “When there’s a quantum interaction at the center of the detector, that event is physically separate from the next one that happens,” Sexton-Kennedy said. “And those two events can be processed in parallel. So, there has to be something that creates more independence in the computing workflow that can split up the work.”

    Sharing the load

    One way to approach this challenge is by distributing the workflow around the world. Mike Kirby of Fermilab and Andrew McNab of the University of Manchester in the UK are the technical leads of the DUNE Computing Consortium, a collective effort by members of the DUNE collaboration and computing experts at partner institutions. Their goal is to establish a global computing network that can handle the massive data dumps DUNE will produce by distributing them across the grid.

    “We’re trying to work out a roadmap for DUNE computing in the next 20 years that can do two things,” Kirby said. “One is an event data model,” which means figuring out how to handle the data the detector produces when a neutrino collision occurs, “and the second is coming up with a computing model that can use the conglomerations of computing resources around the world that are being contributed by different institutions, universities and national labs.”

    It’s no small task. The consortium includes dozens of institutions, and the challenge is ensuring the computers and servers at each are orchestrated together so that everyone on the project can carry out their analyses of the data. A basic challenge, for example, is making sure a computer in Switzerland or Brazil recognizes a login from a computer at Fermilab.

    Coordinating computing resources across a distributed grid has been done before, most notably by the Worldwide LHC Computing Grid, which federates the United States’ Open Science Grid and others around the world. But this is the first time an experiment at this scale led by Fermilab has used this distributed approach.

    “Much of the Worldwide LHC Computing Grid design assumes data originates at CERN and that meetings will default to CERN, but as DUNE now has an associate membership of WLCG things are evolving,” said Andrew McNab, DUNE’s international technical lead for computing. “One of the first steps was hosting the monthly WLCG Grid Deployment Board town hall at Fermilab last September, and DUNE computing people are increasingly participating in WLCG’s task forces and working groups.”

    “We’re trying to build on a lot of the infrastructure and software that’s already been developed in conjunction with those two efforts and extend it a little bit for our specific needs,” Kirby said. “It’s a great challenge to coordinate all of the computing around the world. In some sense, we’re kind of blazing a new trail, but in many ways, we are very much reliant on a lot of the tools that were already developed.”

    Supernovae signals

    Another challenge is that DUNE has to organize the data it collects differently from particle accelerator physics experiments.

    “For us, a typical neutrino event from the accelerator beam is going to generate something on the order of six gigabytes of data,” Kirby said. “But if we get a supernova neutrino alert,” in which a neutrino burst from a supernova arrives, signaling the cosmic explosion before light from it arrives at Earth, “a single supernova burst record could be as much as 100 terabytes of data.”

    One terabyte equals one trillion bytes, an amount of data equal to about 330 hours of Netflix movies. Created in a few seconds, that amount of data is a huge challenge because of the computer processing time needed to handle it. DUNE researchers must begin recording data soon after a neutrino alert is triggered, and it adds up quickly. But it will also offer an opportunity to learn about neutrino interactions that take place inside supernovae while they’re exploding.

    McNab said DUNE’s computing requirements are also slightly different because the size of each of the events it will capture is typically 100 times larger than the LHC experiments like ATLAS or CMS.

    “So, the computers need more memory — not 100 times more, because we can be clever about how we use it, but we’re pushing the envelope certainly,” McNab said. “And that’s before we even start talking about the huge events if we see a supernova.”

    Georgia Karagiorgi, a physicist at Columbia University who leads data selection efforts for the DUNE Data Acquisition Consortium, said a nearby supernova will generate up to thousands of interactions in the DUNE detector.

    “That will allow us to answer questions we have about supernova dynamics and about the properties of neutrinos themselves,” she said.

    To do so, DUNE scientists will have to combine data on the timing of neutrino arrival, their abundance and what kinds of neutrinos are present.

    “If neutrinos have weird, new types of interactions as they’re propagating through the supernova during the explosion, we might expect modifications to the energy distribution of those neutrinos as a function of time” as they are picked up by the detector, Karagiorgi said. “That goes hand-in-hand with very detailed, and also quite computationally intensive, simulations, with different theoretical assumptions going into them, to actually be able to extract our science. We need both the theoretical simulations and the actual data to make progress.”

    Gathering that data is a huge endeavor. When a supernova event occurs, “we read out our far-detector modules for about 100 seconds continuously,” Kirby said.

    Because the scientists don’t know when a supernova will happen, they have to start collecting data as soon as an alert occurs and could be waiting for 30 seconds or longer for the neutrino burst to conclude. All the while, data could be piling up.

    To prevent too much buildup, Kirby said, the experiment will use an approach called a circular buffer, in which memory that doesn’t include neutrino hits is reused, not unlike rewinding and recording over the tape in a video cassette.

    McNab said the supernovae aspect of DUNE is also presenting new opportunities for computing collaboration.

    “I’m a particle physicist by training, and one of my favorite aspects about working on this project is that way that it connects to other scientific disciplines, particularly astronomy,” he said. In the UK, particle physics and astronomy computing are collectively providing support for DUNE, the Vera C. Rubin Observatory Legacy Survey of Space and Time, and the Square Kilometer Array radio telescopes on the same computers. “And then we have the science aspect that, if we do see a supernova, then we will hopefully be viewing it with multiple wavelengths using these different instruments. DUNE provides an excellent pathfinder for the computing, because we already have real data coming from DUNE’s prototype detectors that needs to be processed.”

    Kirby said that the computing effort is leading to exciting new developments in applications on novel architectures, artificial intelligence and machine learning on diverse computer platforms.

    “In the past, we’ve focused on doing all of our data processing and analysis on CPUs and standard Intel and PC processors,” he said. “But with the rise of GPUs [graphics processing units] and other computing hardware accelerators such as FPGAs [field-programmable gate arrays] and ASICs [application-specific integrated circuits], software has been written specifically for those accelerators. That really has changed what’s possible in terms of event identification algorithms.”

    These technologies are already in use for the on-site data acquisition system in reducing the terabytes per second generated by the detectors down to the gigabytes per second transferred offline. The challenge that remains for offline is figuring out how to centrally manage these applications across the entire collaboration and get answers back from distributed centers across the grid.

    “How do we stitch all of that together to make a cohesive computing model that gets us to physics as fast as possible?” Kirby said. “That’s a really incredible challenge.”

    This work is supported by the Department of Energy Office of Science.

    Fermilab is supported by the Office of Science of the U.S. Department of Energy. The 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 energy.gov/science.

    See the full 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. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
    collaborate at Fermilab on experiments at the frontiers of discovery.

     
  • richardmitnick 12:13 pm on April 10, 2020 Permalink | Reply
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    From Fermi National Accelerator Lab: “The cold eyes of DUNE” 

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

    From Fermi National Accelerator Lab , an enduring source of strength for the US contribution to scientific research world wide.

    April 9, 2020
    Jerald Pinson

    How do you detect a particle that has almost no mass, feels only two of the four fundamental forces, and can travel unhindered through solid lead for an entire light-year without ever interacting with matter? This is the problem posed by neutrinos, ghostly particles that are generated in the trillions by nuclear reactions in stars, including our sun, and on Earth. Scientists can also produce neutrinos to study in controlled experiments using particle accelerators. One of the ways neutrinos can be detected is with large vats filled with liquid argon and wrapped with a complex web of integrated circuitry that can operate in temperatures colder than the average day on Neptune.

    Industry does not typically use electronics that operate at cryogenic temperatures, so particle physicists have had to engineer their own. A collaboration of several Department of Energy national labs, including Fermilab, has been developing prototypes of the electronics that will ultimately be used in the international Deep Underground Neutrino Experiment, called DUNE, hosted by Fermilab.

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

    SURF DUNE LBNF Caverns at Sanford Lab

    DUNE will generate an intense beam of neutrinos at Fermilab in Illinois and send it 800 miles through the Earth’s crust to detectors in South Dakota. Results from the experiment may help scientists understand why there is more matter than antimatter, an imbalance that led to the formation of our universe.

    2
    Analog-to-digital convertors built to work at cryogenic temperatures, such as the prototype pictured here, will operate inside of liquid-argon chambers in the Deep Underground Neutrino Experiment. Photo: Alber Dyer, Fermilab

    Physics and chill

    DUNE’s neutrino detectors will be massive: a total of four tanks, each as high as a four-story building, will contain a combined 70,000 tons of liquid argon and be situated in a cavern a mile beneath Earth’s surface.

    FNAL DUNE Argon tank at SURF

    Argon occurs naturally as a gas in our atmosphere, and turning it into a liquid entails chilling it to extremely cold temperatures. The atomic nuclei of liquid argon are so densely packed together that some of the famously elusive neutrinos traveling from Fermilab will interact with them, leaving behind tell-tale signs of their passing. The resulting collision produces different particles that scatter in all directions, including electrons, which physicists use to reconstruct the path of the otherwise invisible neutrino.

    A strong electric field maintained within the detector causes the free electrons to drift toward wires attached to sensitive electronics. As the electrons travel past the wires, they generate small voltage pulses that are recorded by electronics in the liquid-argon chamber. Amplifiers in the chamber then boost the signal by increasing the voltage, after which they are converted to digital data. Finally, the signals collected and digitized across the entire chamber are merged together and sent to computers outside the detector for storage and analysis.

    Challenges for chilled electronics

    The electronics in neutrino detectors work the same way as the technology we use in our everyday lives, with one major exception. The integrated circuitry in our phones, computers, cameras, cars, microwaves and other devices has been developed to operate at or around room temperature, down to about minus 40 degrees Celsius. The liquid argon in neutrino detectors, however, is cooled to around minus 200 degrees.

    “If you use electronics designed to work at room temperature, rarely do you find that they work anywhere nearly as well as those designed to operate at cryogenic temperatures,” said Fermilab scientist David Christian.

    In the past, this issue was sidestepped altogether by placing the electronic circuitry outside of the argon tanks. But when you’re measuring a limited number of electrons, even the slightest amount of electronics noise can mask the signal you’re looking for.

    The easiest way to mitigate the problem involves the same tactic you use to keep food from spoiling: Keep it cold. If all the electronics are submerged in the liquid argon, there are fewer thermal vibrations from atoms and a larger signal-to-noise ratio. Placing the electronics in the liquid-argon tank has the added benefit of decreasing the amount of wire you have to use to deliver signals to the amplifiers. If, for example, amplifiers and analog-to-digital converters are kept outside the chamber (as they are in some neutrino detectors), long wires have to connect them to the detectors on the inside.

    “If you put the electronics inside the cold chamber, you have much shorter wires and therefore lower noise,” said Carl Grace, an engineer at Lawrence Berkeley National Laboratory. “You amplify the signal and digitize it in the argon chamber. You then have a digital interface to the outside world in which noise is no longer a concern.”

    There are several design challenges these teams have had to overcome during development, not the least of which was determining how to test the durability of the devices.

    “These chips will have to operate for a minimum of 20-odd years, hopefully longer,” Grace said. “And because of the nature of the argon chambers, the electronics that get put inside of them can’t cannot be changed. They cannot be swapped out or repaired in any way.”

    Since Grace and his team don’t have 20 years in which to test their prototypes, they’ve approximated the effects of aging by increasing the amount of voltage powering the chips to simulate the wear and tear of regular, long-term operation.

    “We take the electronics, cool them down and then elevate their voltage to accelerate their aging,” Grace said. “By observing their behavior over a relatively short period of time, we can we can then estimate how long the electronics would last if they were operated at the voltages for which they were designed.”

    Resistance in circuits

    Not only do these circuits need to be built to last for decades, they also need to be made more durable in another way.

    Electronic circuitry has a certain amount of resistance to the electric current flowing through it. As electrons pass through a circuit, they interact with the vibrating atoms within the conducting material, which slows them down. But these interactions are reduced when the electronics are cooled to cryogenic temperatures, and the electrons that constitute the signal move more quickly on average.

    This is a good thing in terms of output; the integrated circuits being built for DUNE will work more efficiently when placed in the liquid argon. But, as the electrons travel faster through the circuits as temperatures drop, they can begin to do damage to the circuitry itself.

    “If electrons have a high enough kinetic energy, they can actually start ripping atoms from the crystal structure of the conducting material,” Grace said. “It’s like bullets hitting a wall. The wall starts to lose integrity over time.”

    DUNE chips are designed to mitigate this effect. The chips are fabricated using large constituent devices to minimize the amount of damage accrued, and they are used at lower voltages than normally used at room temperature. Scientists can also adjust operating parameters over time to compensate for any damage that occurs during their many years of use.

    Timeline to completion

    With preparations for the DUNE well under way and the experiment slated to begin generating data by 2027, scientists from many institutions have been hard at work developing electronic prototypes.

    Scientists at Brookhaven National Laboratory are working on perfecting the amplifier, while teams from Fermilab, Brookhaven and Berkeley labs are collaborating on the analog-to-digital converter design.

    Fermilab has also teamed up with Southern Methodist University to develop the electronic component that merges all of the data within an argon tank before it’s transmitted to electronics located outside the cold detector. Finally, researchers working on a competing design at SLAC National Accelerator Laboratory are trying to find a way to efficiently combine all three components into one integrated circuit.

    The various teams plan to submit their circuit designs this summer for review. The selected designs will be built and ultimately installed in the DUNE neutrino detectors at the Sanford Underground Neutrino Facility in South Dakota.

    SURF-Sanford Underground Research Facility, Lead, South Dakota, USA

    U.S. work on LBNF/DUNE is supported by the Department of Energy Office of Science.

    See the full here.


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    FNAL Icon

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

     
  • richardmitnick 12:50 pm on March 28, 2020 Permalink | Reply
    Tags: "March Magnets", 1. Quadrupole magnet for linear particle accelerator, 2. Superconducting focusing magnet for particle collider, 3. Bending magnet for circular accelerator, 4. Undulator for light source, 5. Solenoid for particle detector, 6. Kicker magnet for particle accelerator, 7. Storage ring magnet, 8. Magnetic horn for neutrino beam, FNAL, Illustrations by Jerald Pinson.   

    From Fermi National Accelerator Lab: “March Magnets” 

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

    From Fermi National Accelerator Lab , an enduring source of strength for the US contribution to scientific research world wide.

    March 27, 2020
    Maura Barone
    Lauren Biron
    Leah Hesla
    Jerald Pinson
    Kurt Riesselmann

    Missing March Madness? Let Fermilab fill a small part of the void created in these times of social distancing and sheltering-in-place. Participate in our sendup of the NCAA tournament: March Magnets.

    Particle physics fans know that magnets are major players in the instruments scientists use to examine the universe’s smallest constituents. Less appreciated is their sheer variety: diverse purposes, sizes, shapes and materials.

    Below are eight distinct magnet types used in particle physics, each with an example from a project or experiment in which the U.S. Department of Energy’s Fermilab is a player. We start at Elite Eight stage of the playoffs. So add these eight magnets to your repertoire of particle physics knowledge.

    Then on Monday, March 30, head over to the Fermilab Twitter feed to participate in our March Magnets playoffs. On Monday and Tuesday, March 30 and 31, you can vote on which four of our eight magnets get to advance to the next stage. Vote for your Final Four on Friday, April 3. And vote for the champion on Monday, April 6.

    The champion will be announced on Fermilab’s Twitter feed.

    Want to understand how magnets work in the field of particle physics? Read a Physics 101 primer of magnets’ roles in accelerators.

    Have fun with our March Magnets tournament!

    _______________________________________________________________________

    1. Quadrupole magnet for linear particle accelerator

    2
    PIP-II quadrupole magnet. Photo: Reidar Hahn, Fermilab

    What is it?

    Physicists use sequences of quadrupole magnets to keep particle beams focused as they travel through a particle accelerator. At the exact center of these magnets, the magnetic field is zero, and particles feel no force. But the farther a particle deviates from the ideal beam trajectory that goes through the center of these magnets, the stronger the magnetic field. It is these fields that push the charged particles back to the center of the magnet and keep the beam on track.

    Example

    PIP-II linear accelerator quadrupole magnet at Fermilab

    Why it’s cool

    The 26 quadrupole magnets of the new PIP-II linear accelerator at Fermilab, built as in-kind international contributions by the Bhabha Atomic Research Center in India, each have four coils made of copper wire, arranged in alternating orientation (north-south-north-south). The challenge is that a single quadrupole magnet only can create a focusing force in one direction perpendicular to the beam (x axis), and it defocuses the beam in the other direction perpendicular to the beam (y axis). The solution is the installation of a second magnet with switched polarization (south-north-south-north) to create a focusing force along the y-axis direction. The installation of a carefully calculated and placed series of quads with different polarizations, often designed as doublet and triplet magnets, produces a net focusing force and helps ensure that the protons will stay on track.

    Specifications for PIP-II quadrupole magnet

    Size: 0.1 meters long and 0.33 meters high and wide
    Weight: 57 kilograms
    Electric current: 10 amps DC peak
    Strength: 1.5 teslas integrated peak field
    Polarity/magnetic field: quadrupole
    Permanent, superconducting, normal-conducting: normal-conducting electromagnet
    Material: copper, magnetic steel, stainless steel

    3

    _______________________________________________________________________

    2. Superconducting focusing magnet for particle collider

    4
    HL-LHC focusing magnet. Photo: Dan Cheng, Lawrence Berkeley National Laboratory

    What is it?

    A focusing magnet squeezes a charged-particle beam, making it as tight and compact as experiments require. In particle colliders, the stronger the magnets that focus the opposing beams before they reach the collision point, the more collisions the machine produces.

    Example

    Focusing magnet for the High-Luminosity LHC at CERN

    Why it’s cool

    At present, the Large Hadron Collider at CERN has superconducting focusing magnets built with niobium-titanium wire. Now Berkeley Lab, Brookhaven Lab, CERN and Fermilab are working on replacing these magnets as part of the HL-LHC upgrade. The new magnets feature niobium-tin wire, and the first production magnet achieved the required field strength of 11.5 teslas in a test at Brookhaven Lab, a triumph of painstaking and innovative engineering by the U.S. team. It is the result of years of R&D development and understanding how to take advantage of this superior but fragile superconducting material. When installed in the HL-LHC in a few years, it will be the first time a focusing magnet made from niobium-tin will operate in a particle accelerator anywhere in the world.

    Specifications for High-Luminosity LHC focusing magnet (Q1 and Q3)

    Size: 4.7 meters long, 60 centimeters in diameter
    Weight: 6.8 metric tons
    Electric current: 16,500 amps for 7-TeV beams
    Magnetic field strength: 11.5 teslas
    Polarity/magnetic field: quadrupole
    Permanent, normal-conducting or superconducting: superconducting electromagnet
    Material: niobium-tin, iron, aluminum

    5

    _______________________________________________________________________

    3. Bending magnet for circular accelerator

    5
    Main Injector bending magnet. Photo: Reidar Hahn, Fermilab

    What is it?

    A bending magnet bends the path of a charged-particle beam. Scientists use them to keep a beam on its track in a ring-shaped accelerator. As the machine propels the beam to higher energy, operators keep the particles on their orbit by increasing the electric current in the steering magnets, which increases the strength of the magnet field.

    Example

    Main Injector bending magnet at Fermilab

    Why it’s cool

    The Main Injector bending magnet is, in a word, elegant. And the lab built lots of them, with help from collaborators. Three hundred forty-four bending magnets bend the beam around the Main Injector’s three-kilometer ring. The magnet’s design addresses nearly all of the engineering problems that bedeviled its progenitors. For example, rather than being immovably fixed inside its steel housing, the main magnet component is attached to a sliding mechanism so that, when it expands, it is also free to move, avoiding the stress a fixed component would experience. The copper-wire magnets have performed flawlessly for more than 25 years. Another magnet under development may soon rival it for best magnet: A new Fermilab-designed bending magnet based on superconducting niobium-tin wire is in the development phase for a future very-high-energy particle collider. A demonstrator magnet built by Fermilab set a world record when it achieved a peak magnetic field of 14.1 teslas in 2019.

    Main Injector bending magnet

    Size: two sizes: 4 meters and 6 meters long; roughly 1 meter high and wide
    Weight: about 20 tons
    Electric current: 9,400 amps DC peak
    Strength: 1.7 teslas peak field
    Polarity/magnetic field: dipole
    Permanent, normal-conducting or superconducting: normal-conducting electromagnet
    Material: copper, steel

    6

    _______________________________________________________________________

    4. Undulator for light source

    7
    LCLS-II undulator. Photo: Lawrence Berkeley National Laboratory

    What is it?

    Want to make a particle beam shimmy? Use an undulator, a series of magnets in an electron accelerator. Because the direction of the magnetic field changes from magnet to magnet, the undulator forces a beam into a fast-moving zigzag, rapidly moving left and right. With each zig and zag, the electron beam radiates particles of light, or photons. Scientists use this light to study microscopic details of nature, such as the molecular structure of proteins, how medicine affects cells or the components of air pollution. The spectrum of the light depends on the energy of the particle beam and typically ranges from infrared to ultraviolet and X-rays.

    Example

    Undulator for the LCLS-II electron accelerator at SLAC

    Why it’s cool

    Unlike most light sources, the LCLS-II under construction at SLAC National Accelerator Laboratory features a linear electron accelerator. It propels more electrons to higher energy than typical light sources. Lawrence Berkeley National Laboratory manages the production of the LCLS-II undulators. LCLS-II’s 37 accelerator cryomodules, which power the electron beam before it enters the undulator line, were built by Fermilab and Jefferson Lab.

    The light produced by the undulators of the LCLS-II takes the form of X-rays. Twenty-one undulators produce soft (lower-energy) X-rays; 32 produce hard (higher-energy) X-rays.

    LCLS-II’s soft X-ray undulators are arranged in two rows, which can be adjusted to within millionths of an inch to tune the properties of the X-ray light. They produce up to 1 million soft X-ray pulses per second. The undulators will provide the worldwide brightest X-ray pulses in a wide energy range, from 200 to 25,000 electronvolts, and the photon power will range between several hundred and 1,000 watts.

    Specifications for LCLS-II accelerator undulator

    Size: 3.4 meters long, 2 meters high
    Weight: about 6.5 tons
    Strength: 1.5-tesla peak field
    Polarity/magnetic field: alternating dipole polarity
    Permanent, normal-conducting or superconducting: hybrid permanent magnets
    Material: vanadium permendur energized by a permanent magnet

    8

    _______________________________________________________________________

    5. Solenoid for particle detector

    9
    CMS magnet. Photo: CERN

    What is it?

    A solenoid is a cylindrical electromagnet made of many loops of current-carrying cable, which produces a constant magnetic field along its length. Inside a particle detector, a solenoid is responsible for bending the trajectories of particles that fly through it: Positively charged particles bend one way, and negatively charged particles bend the other. A detector’s solenoid also reveals the particle’s momentum: the faster a particle, the less bending of its path. By analyzing the trajectories, scientists can determine the energy and momentum of each particle.

    Example

    CMS at CERN

    Why it’s cool

    Despite its size, the CMS detector at the Large Hadron Collider is relatively compact for all the material and devices it contains, much smaller than its cousin, the ATLAS detector. Still, its solenoid is a giant — the largest superconducting magnet ever made. Multiple institutions and companies contributed to its construction. It contains almost twice as much iron as the Eiffel Tower, and it stores enough energy to melt 18 tons of gold. The winding of the solenoid cable took five years. Its size and design are optimized for detecting and measuring particles known as muons very accurately.

    Specifications for Compact Muon Solenoid (CMS)

    Size: 13 meters long by 6 meters high
    Weight: about 12,000 tons
    Electric current: 19,500 amps (nominal current)
    Strength: 3.8 teslas
    Polarity/magnetic field: axial field
    Permanent, normal-conducting or superconducting: superconducting electromagnet
    Material: iron, aluminum, niobium-titanium

    10

    _______________________________________________________________________

    6. Kicker magnet for particle accelerator

    11
    Booster kicker magnet. Photo: Salah Chaurize, Fermilab

    What is it?

    Kicker magnets are used in particle accelerators to deflect or transfer a particle beam from its main path, sending particles out of the accelerator and into a beamline that guides the beam to its final destination.

    Example

    Booster kicker magnet at Fermilab

    Why it’s cool

    In the circular Booster accelerator at Fermilab, there are five extraction kicker magnets positioned around the ring. As the beam’s energy ramps up, the particles approach the speed of light as they circle through the Booster. Once the beam reaches its extraction energy, an electrical pulse is transmitted to the five magnets in unison, kicking the beam out of the Booster ring. Because the particle beam passes through the Booster and its kicker magnets up to an astounding 20,000 times a second, the magnets have to activate at unimaginably fast speeds — within 35 nanoseconds — to kick the beam out at exactly the right moment.

    Specifications for Booster kicker magnet

    Size: 1 or 0.5 meters long (two types), 12 centimeters wide
    Weight: 64 kilograms for 1-meter-long magnet
    Electric current: 1,200 amps DC peak
    Strength: 0.0072 teslas
    Polarity/magnetic field: dipole
    Permanent, superconducting or normal-conducting: normal-conducting electromagnet
    Material: copper, aluminum, ferrite ceramic, RTV (silicone rubber)

    12

    _______________________________________________________________________

    7. Storage ring magnet

    13
    Muon g-2 storage ring and magnet. Photo: Reidar Hahn, Fermilab

    What is it?

    Lots of interesting physics experiments need to build up and store bunches of particles. Storage rings are designed to circulate particles from a few seconds to hundreds of hours. Electron storage rings, for example, allow scientists to study the synchrotron radiation the particles emit. Alternatively, scientists can extract the stored particles from the ring and smash them into a fixed target. A collider typically features two intersecting storage rings on top of each other to create head-on collisions of particles.

    Example

    Muon g-2 storage ring magnet at Fermilab

    Why is it cool?

    Most storage rings circulate electrons or protons using a series of magnets. In contrast, the Muon g-2 storage ring at Fermilab circulates muons using one giant magnet: 50 feet in diameter. Built in the 1990s at Brookhaven Lab for its Muon g-2 experiment, the magnet made its journey by boat and truck from New York to Illinois in 2013. The Muon g-2 magnetic field is incredibly uniform for such a large magnet, with a magnetic field that’s identical around the ring at the parts-per-billion level. It has to be so precise because scientists are measuring the “wobble” of the muons traveling through the ring — so if the field varied too much, the muon would behave differently in those areas. The expected announcement of the first results from the Muon g-2 experiment at Fermilab are among the most anticipated physics results of 2020 and, if they confirm the tantalizing hints observed at Brookhaven Lab, could upend the current Standard Model of particle physics.

    Specifications for Muon g-2 magnet

    Size: 15.3 meters in diameter, 1.5 meters tall
    Weight: 700 tons
    Electrical current: 5,200 amps
    Strength: 1.45 tesla
    Polarity/magnetic field: C-shaped dipole magnets and electrostatic quadrupole plates
    Permanent, superconducting or normal-conducting: superconducting electromagnet
    Material: iron and superconducting wire (pure aluminum stabilizer and niobium-titanium superconductor in a copper matrix)

    14
    _______________________________________________________________________

    8. Magnetic horn for neutrino beam

    15
    Neutrino horn. Photo: Reidar Hahn, Fermilab

    What is it?

    Powered by extreme pulses of electricity, magnetic horns turn a broad spray of particles into a focused beam, making for better experiments. Horns typically focus electrically charged particles called pions and kaons, which then decay into various types of particles, including no-charge neutrinos that can no longer be steered by magnets. Because the charged particles are steered by the magnets, the neutrinos they give birth to also continue along well-defined paths. Also called “focusing horns,” these devices live in harsh conditions and make accelerator-based neutrino experiments possible.

    Example

    NuMI focusing horn at Fermilab

    Why is it cool?

    The focusing horn for the Neutrinos at the Main Injector facility receives its beam from Fermilab’s most powerful particle accelerator, the two-mile-circumference Main Injector. The magnetic horn turns on and off rapidly, with every pulse clocking in around 200,000 amps. (Your toaster runs at around 10 amps). Horns must survive extreme thermal and magnetic stress over their lifetimes – the equivalent of being hit with a hammer 10 million times a year. Without the horn, an experiment would lose 95% of the neutrinos in its beam.

    Specifications for NuMI focusing horn:

    Size: 3 meters long
    Weight: about 1 ton
    Electrical current: 200,000 amps
    Strength: 1 tesla
    Polarity/magnetic field: toroidal magnetic field
    Permanent, superconducting or normal-conducting: normal-conducting electromagnet
    Material: nickel-plated aluminum and anodized aluminum

    16

    _______________________________________________________________________

    Illustrations by Jerald Pinson.

    Accelerator magnet research and development at Fermilab is supported by the DOE Office of Science.

    Fermilab is supported by the Office of Science of the U.S. Department of Energy. The 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, visit http://www.science.energy.gov.

    See the full here.


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    FNAL Icon

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

     
  • richardmitnick 2:26 pm on March 18, 2020 Permalink | Reply
    Tags: "Three national laboratories achieve record magnetic field for accelerator focusing magnet", , FNAL, , Magnets for the HL-LHC., The ingredient that sets these U.S.-produced magnets apart is niobium-tin.   

    From Fermi National Accelerator Lab: “Three national laboratories achieve record magnetic field for accelerator focusing magnet” 

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

    From Fermi National Accelerator Lab , an enduring source of strength for the US contribution to scientific research world wide.

    March 18, 2020

    Media contacts

    Fermilab Office of Communication, media@fnal.gov, 630-840-3351
    Karen McNulty Walsh, Brookhaven National Laboratory, kmcnulty@bnl.gov, 631-344-8350, 917-699-0501
    Laurel Kellner, Lawrence Berkeley National Laboratory, lkellner@lbl.gov, 510-590-8034

    In a multiyear effort involving three national laboratories from across the United States, researchers have successfully built and tested a powerful new magnet based on an advanced superconducting material. The eight-ton device — about as long as a semi-truck trailer — set a record for the highest field strength ever recorded for an accelerator focusing magnet and raises the standard for magnets operating in high-energy particle colliders.

    The Department of Energy’s Fermilab, Brookhaven National Laboratory and Lawrence Berkeley National Laboratory designed, built and tested the new magnet, one of 16 they will provide for operation in the High-Luminosity Large Hadron Collider at CERN laboratory in Europe.

    The 16 magnets, along with another eight produced by CERN, serve as “optics” for charged particles: They will focus beams of protons into a tiny, infinitesimal spot as they approach collision inside two different particle detectors.

    The ingredient that sets these U.S.-produced magnets apart is niobium-tin – a superconducting material that produces strong magnetic fields. These will be the first niobium-tin quadrupole magnets ever to operate in a particle accelerator.

    Like the current Large Hadron Collider, its high-luminosity successor will smash together beams of protons cruising around the 17-mile ring at close to the speed of light. The HL-LHC will pack an additional punch: It will provide 10 times the collisions that are possible at the current LHC. With more collisions come more opportunities to discover new physics.

    And the machine’s new focusing magnets will help it achieve that leap in delivered luminosity.

    “We’ve demonstrated that this first quadrupole magnet behaves successfully and according to design, based on the multiyear development effort made possible by DOE investments in this new technology,” said Fermilab scientist Giorgio Apollinari, head of the U.S. Accelerator Upgrade Project, which leads the U.S.-based focusing-magnet project.

    “It’s a very cutting-edge magnet, really on the edge of magnet technology,” said Brookhaven National Laboratory scientist Kathleen Amm, the Brookhaven representative for the Accelerator Upgrade Project.

    What makes it successful is its impressive ability to focus.

    2
    This new magnet reached the highest field strength ever recorded for an accelerator focusing magnet. Designed and built by Fermilab, Brookhaven National Laboratory and Lawrence Berkeley National Laboratory, it will be the first niobium-tin quadrupole magnet ever to operate in a particle accelerator — in this case, the future High-Luminosity Large Hadron Collider at CERN. Photo: Dan Cheng, Lawrence Berkeley National Laboratory

    Focus, magnets, focus

    In circular colliders, two beams of particles race around the ring in opposite directions. An instant before they reach the collision point, each beam passes through a series of magnets that focus the particle beams into a tiny, infinitesimal spot, much the way lenses focus light rays to a point. Now packed as tightly with particles as the magnets can get them — smash! — the beams collide.

    The scientific fruitfulness of that smash depends on how dense the beam is. The more particles that are crowded into the collision point, the greater the chance of particle collisions.

    You get those tightly packed beams by sharpening the magnet’s focus. One way to do that is to widen the lens. Consider light:

    “If you try to focus the light from the sun using a magnifying glass at a small point, you want to have a more ‘powerful’ magnifying glass,” said Ian Pong, Berkeley Lab scientist and one of the control account managers.

    A larger magnifying glass focuses more of the sun’s rays than a smaller one. However, the light rays at the outer rim of the lens have to be bent more sharply in order to approach the same focal point.

    Or consider a group of archers shooting arrows at an apple: More arrows will stick if the archers shoot from above, below and either side of the apple than if they are stationed at one post, firing from the same position.

    The analog of the magnifying glass size and the archer array is the magnet’s aperture — the opening of the passageway the beam takes as it barrels through the magnet’s interior. If the particle beam is allowed to start wide before being focused, more particles will arrive at the intended focal point — the center of the particle detector.

    The U.S. team widened the LHC focusing magnet’s aperture to 150 millimeters, more than double the current aperture of 70 millimeters.

    But of course, a wider aperture isn’t enough. There is still the matter of actually focusing the beam, which means forcing a dramatic change in the beam’s size, from wide to narrow, by the time the beam reaches the collision point. And that requires an exceptionally strong magnet.

    “The magnet has to squeeze the beam more powerfully than the LHC’s present magnets in order to create the luminosity needed for the HL-LHC,” Apollinari said.

    To meet the demand, scientists designed and constructed a muscular focusing magnet, calculating that, at the required aperture, it would have to generate a field exceeding 11.4 teslas. This is up from the current 7.5-tesla field generated by the niobium-titanium-based LHC quadrupole magnets. (For accelerator experts: The HL-LHC integrated luminosity goal is 3,000 inverse femtobarns.)

    In January, the three-lab team’s first HL-LHC focusing magnet delivered above the goal performance, achieving an 11.5-tesla field and running continuously at this strength for five straight hours, just as it would operate when the High-Luminosity LHC starts up in 2027.

    “These magnets are the currently highest-field focusing magnets in accelerators as they exist today,” Amm said. “We’re really pushing to higher fields, which allows us to get to higher luminosities.”

    The new focusing magnet was a triumph, thanks to niobium-tin.

    Magnet makers: Three U.S. labs are building powerful magnets for the world’s largest powerful collider from Berkeley Lab on Vimeo.

    Niobium-tin for the win

    The focusing magnets in the current LHC are made with niobium-titanium, whose intrinsic performance limit is generally recognized to have been reached at 8 to 9 teslas in accelerator applications.

    The HL-LHC will need magnets with around 12 teslas, about 250,000 times stronger than the Earth’s magnetic field at its surface.

    “So what do you do? You need to go to a different conductor,” Apollinari said.

    Accelerator magnet experts have been experimenting with niobium-tin for decades. Electrical current coursing through a niobium-tin superconductor can generate magnetic fields of 12 teslas and higher — but only if the niobium and tin, once mixed and heat treated to become superconductive, can stay intact.

    “Once they’re reacted, it becomes a beautiful superconductor that can carry a lot of current, but then it also becomes brittle,” Apollinari said.

    Famously brittle.

    “If you bend it too much, even a little bit, once it’s a reacted material, it sounds like corn flakes,” Amm said. “You actually hear it break.”

    Over the years, scientists and engineers have figured out how to produce niobium-tin superconductor in a form that is useful. Guaranteeing that it would hold up as the star of an HL-LHC focusing magnet was another challenge altogether.

    Berkeley, Brookhaven and Fermilab experts made it happen. Their assembly process is a delicate, involved operation balancing niobium-tin’s fragility against the massive changes in temperature and pressure it undergoes as it becomes the primary player in a future collider magnet.

    The process starts with wires containing niobium filaments surrounding a tin core, provided by an outside manufacturer. The wires are then fabricated into cables at Berkeley in just the right way. The teams at Brookhaven and Fermilab then wind these cables into coils, careful to avoid deforming them excessively. They heat the coils in a furnace in three temperature stages, a treatment that takes more than a week. During heat treatment the tin reacts with the filaments to form the brittle niobium-tin.

    Having been reacted in the furnace, the niobium-tin is now at its most fragile, so it is handled with care as the team cures it, embedding it in a resin to become a solid, strong coil.

    That coil is now ready to serve as one of the focusing magnet’s four poles. The process takes several months for each pole before the full magnet can be assembled.

    “Because these coils are very powerful when they are energized, there is a lot of force trying to push the magnet apart,” Pong said. “Even if the magnet is not deforming, at the conductor level there will be a strain, to which niobium-tin’s performance is very sensitive. The management of the stress is very, very important for these high-field magnets.”

    Heat treating the magnet coils — one of the intermediate steps in the magnet’s assembly — is also a subtle science. Each of the four coils of an HL-LHC focusing magnet weighs about one ton and has to be heat-treated evenly — inside and out.

    “You have to control the temperature well. Otherwise the reaction will not give us the best performance,” Pong said. “It’s a bit like cooking. It’s not just to achieve the temperature in one part of the coil but in the entire coil, end to end, top to bottom, the whole thing.”

    And the four coils have to be aligned precisely with one another.

    “You need very high field precision, so we have to have very high precision in how they align these to get good magnetic-field uniformity, a good quadrupole field,” Amm said.

    The fine engineering that goes into the U.S. HL-LHC magnets has sharpened over decades, with a payoff that is energizing the particle accelerator community.

    “This will be the first use of niobium-tin in accelerator focusing magnets, so it will be pretty exciting to see such a complex and sophisticated technology get implemented into a real machine,” Amm said.

    “We were always carrying the weight of responsibility, the hope in the last 10, 20 years — and if you want to go further, 30, 40 years — focusing on these magnets, on conductor development, all the work,” Pong said. “Finally, we are coming to it, and we really want to make sure it is a lasting success.”

    5
    The magnet gets ready for a test at Brookhaven National Laboratory. Photo: Brookhaven National Laboratory.

    The many moving parts of an accelerator collaboration

    Ensuring lasting success has as much to do with the operational choreography as it does with the exquisite engineering. Conducting logistics that span years and a continent requires painstaking coordination.

    “Planning and scheduling are very important, and they’re quite challenging,” Pong said. “For example, transportation communication: We have to make sure that things are well protected. Otherwise these expensive items can be damaged, so we have to foresee issues and prevent them. Delays also have an impact on the whole project, so we have to ensure components are shipped to destination in a timely schedule.”

    Amm, Apollinari and Pong acknowledge that the three-lab team have met the challenges capably, operating as a well-oiled machine.

    “The technologies developed at Fermilab, Brookhaven and Berkeley helped make the original LHC a success. And now again, these technologies out of the U.S. are really helping CERN be successful,” Amm said. “It’s a dream team, and it’s an honor to be a part of it.”

    The U.S.-based Accelerator Upgrade Project for the HL-LHC, of which the focusing-magnet project is one piece, kicked off in 2016, growing out of a 2003 predecessor R&D program that focused on similar accelerator technology projects.

    From now until about 2025, the U.S. labs will continue to build the large, hulking tubes, starting with fine strands of niobium and tin. They plan to begin delivering in 2022 the first of 16 magnets, plus four spares, to CERN. Installation will take place over the three years following.

    “People say that ‘touchdown’ is a very beautiful word to describe the landing of an airplane, because you have a huge metal object weighing hundreds of tons, descending from the sky, touching a concrete runway very gently,” Pong said. “These magnets are not too different from that. Our magnets are massive superconducting devices, focusing tiny invisible particle beams that are flying close to the speed of light through the bore. It’s quite magical.”

    The magic starts in 2027, when the High-Luminosity LHC comes online.

    “We are doing today the work that future young researchers will use in 10 or 20 years from now to push the frontier of human knowledge, just like it happened when I was a young researcher here at Fermilab, using the Tevatron,” Apollinari said. “It’s a generational passing of the baton. We need to make the machines for the future generations, and with this technology, obviously what we can enable for the future generation is a lot.”

    Learn more about the High-Luminosity LHC in Symmetry and in an 11-minute Fermilab YouTube video.

    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, a joint partnership between the University of Chicago and the Universities Research Association, Inc. Visit Fermilab’s website at http://www.fnal.gov and follow us on Twitter at @Fermilab.

    This accelerator magnet work is supported by the Department of Energy Office of Science.

    See the full here.


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    Please help promote STEM in your local schools.

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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. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
    collaborate at Fermilab on experiments at the frontiers of discovery.

     
  • richardmitnick 2:29 pm on March 17, 2020 Permalink | Reply
    Tags: , , , Fermilab’s expertise in cryogenic cooling also contributes to Dark SRF’s ability to explore new ground in the search for dark photons., FNAL, If a dark photon indeed exists the filled superconducting cavity acts as a transmitting antenna of dark photons., If dark photons exist it is their ability to travel through walls that the Dark SRF team will use to identify them., , The Dark SRF experiment, The superconducting accelerator cavity, The team has repurposed technology developed for particle accelerators.   

    From Fermi National Accelerator Lab: “Quantum and accelerator science enable mysterious dark sector searches at Fermilab” 

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

    From Fermi National Accelerator Lab , an enduring source of strength for the US contribution to scientific research world wide.

    March 16, 2020
    Bailey Bedford

    Photons are the fundamental particles of light. They illuminate our world, letting us see the universe we live in. But light has failed to show us an extraordinary 85% of the matter in the universe, called Dark Matter. Scientists hope that an as yet unseen cousin of the photon, called a dark photon, will provide a clue about the nature of this mysterious dark matter.

    A dark photon may sound like a contradiction in terms, but physicists use it to describe the hypothesized, photon-like particles that simply pass through ordinary matter. These invisible particles are part of the hypothetical dark sector — less ominously known as the hidden sector — of quantum fields and particles.

    Scientists Anna Grassellino, Roni Harnik and Alexander Romanenko lead the Dark SRF experiment at the U.S. Department of Energy’s Fermilab. To search for the elusive particles, the team has repurposed technology developed for particle accelerators. The researchers hope to generate dark photons and then spot signs of them traveling through solid metal.

    The theorized dark photon has the same properties as a photon, but a different mass — that is, if it has any mass. (Photons are massless.) Also, dark photons and photons are inextricably linked: One type can morph into the other, and dark photons interact with matter only through this transforming act.

    Fundamental particles are already known to come in varied copies of each other. For example, the familiar electron has two similar, heavier cousins — the muon and tau. That pattern is an important motivation in looking for dark photons, explained Harnik, the main theorist on the project.

    “The fact that the muon exists as a copy of the electron makes one wonder whether nature tends to have several copied of each particle. If so, perhaps there is a similar replication of the photon,” Harnik said. “That’s the dark photon.”

    Although theorists can propose the dark photon, theory alone cannot predict its mass or its interaction probability. Experimenters and observers have been able to eliminate broad swaths of possible properties. But the search in unexplored territory is on.

    Grassellino, who is the Fermilab deputy chief technology officer and led the organization of the experiment, explained that theorists are pushing experimentalists “in all possible directions to fill this map and say, ‘Oh, nothing here, nothing here, nothing here. Where else should we look?’”

    1
    During experimental runs of Dark SRF, two cavities (shown here) are bathed in liquid helium to keep them cold. One is held perfectly still, tuned to a specific frequency and kept as empty of photons as possible. The other cavity, which is intended to generate dark photons, has a special setup to adjust it to match the frequency of the first cavity in real time. The experiment aims to catch photons produced in the adjustable cavity as they make their ghostly journey, through metal walls, into the empty cavity. Photo: Reidar Hahn, Fermilab.

    A technological case of adaptive reuse.

    The Dark SRF experiment searches for dark photons in a region that researchers have yet to probe. The region might be said to be low-hanging fruit for Fermilab, but it would be more accurate to say that Fermilab had already designed and built a tall enough ladder to easily harvest new dark photon fruit.

    This metaphorical ladder is the superconducting accelerator cavity. Cavities are hollow, metal, resonating structures in particle accelerators that push particles to near the speed of light. Over the last decade or so, Fermilab has made sweeping strides in increasing their efficiency, getting particles to higher energies over shorter distances.

    Romanenko was the first to realize that Fermilab’s cavities are seemingly tailor-made for a different use and could be instrumental in the search for dark photons.

    “At Fermilab, we have unique technologies that we’re pushing to unprecedented levels of sensitivity or efficiency,” Grassellino said. “We recognize that we need to also make the effort to either think of what we can do with it for unique experiments like Dark SRF or make them available to the other experimenters.”

    In Dark SRF, the superconducting cavity is designed so that photons of a specific microwave energy oscillate together, bouncing back and forth inside it about a 100 billion times before being lost. The cavity maintains the microwaves in much the way a bell or tuning fork maintains sound vibrations.

    When kept filled, a cavity can contain around 10 septillion photons — a 1 followed by 25 zeroes. That’s about the number grains of sand in all the deserts and beaches in one thousand Earths (based on a high estimate of how sandy Earth is). The cavity’s astronomically high photon capacity makes it perfect for coaxing hypothetical dark photons out of their hiding place: Each of those regular photons has some chance of being converted into its dark counterpart — an alluring bet that dark photons will be seen, if they exist.

    “If a dark photon indeed exists, the filled superconducting cavity acts as a transmitting antenna of dark photons,” Harnik said.

    In addition to their excellence in storing photons, the cavities can also keep out stray light, creating a perfect place to hunt for photons arriving unexpectedly. In Dark SRF, a second empty cavity would pick up a dark-photon signal that originated from the 10 septillion photons vibrating inside the first.

    “The beauty of this experiment is it’s so simple, given that we have all this technology in hand,” Romanenko said. “We’re starting to push these cavities into the quantum regime, pairing a cavity bursting with photons with another almost completely devoid of them and being able to detect a single one.”

    A dark photon’s journey.

    If dark photons exist, it is their ability to travel through walls that the Dark SRF team will use to identify them. The Dark SRF experiment brings significantly improved technology to a type of undertaking called a “light shining through a wall” experiment, which looks for light making a seemingly impossible journey through an opaque barrier.

    The experiment uses two cavities, one above the other, that are bathed in liquid helium to keep them cold. One is held perfectly still, tuned to a specific frequency and kept as empty of photons as possible. The other cavity, which is intended to generate dark photons, has a special setup to adjust it to match the frequency of the other cavity in real time.

    The experiment aims to catch photons produced in the adjustable cavity as they make their ghostly journey, through metal walls, into the empty cavity.

    The journey begins when some of the 10 septillion photons that are bouncing around the tunable cavity convert into dark photons, which then pass through the wall of that cavity. Dark photons’ lack of interaction with mundane matter makes them invisible to us. It also renders the walls of the cavities, and everything else, intangible to them. Some of these dark photons will travel into the other cavity, and some fraction of those will revert into regular photons.

    The appearance of these seemingly teleported photons signals the existence of their dark cousins. Sighting them would be the eureka moment.

    2
    The Dark SRF team at Fermilab is advancing the search for dark photons. Photo: Reidar Hahn, Fermilab.

    The Dark SRF difference.

    The success of Dark SRF’s simple design hinges on the extraordinarily fine calibration of the two chambers. The second chamber acts as a trap, capturing the reverted photons. But it will build up a noticeable number only if the two chambers’ frequencies precisely match. Otherwise, the photons’ journeys end with them being quickly absorbed by the second chamber’s walls, never to be seen, and the dark photon will continue to fly under the radar.

    How fine must the calibration be? The required alignment is unforgiving: The roughly quarter-meter-long cavities must be perfectly positioned to within a billionth of a meter. That’s like correctly plotting the length of a regulation soccer field to within the length of a chromosome.

    And once in harmony, these chambers become magnificently sensitive antennas. This is thanks to their high quality factor, a measure of how efficiently they retain energy. The higher the quality factor, the more photons the generating cavity produces, and the more sensitive to dark photons the receiving cavity becomes. The Dark SRF cavities have a quality factor of 1011 when chilled to 1.4 kelvins — the highest-efficiency engineered resonators in the world [Physical Review Applied]. Their quality factor leads to both a flood of potential progenitor photons and heightened sensitivity — both of which give scientists a fighting chance of plucking a dark photon from the vacuum.

    Fermilab’s expertise in cryogenic cooling also contributes to Dark SRF’s ability to explore new ground in the search for dark photons. Any photons converted from dark photons must be picked out from a background crowd of other, normal photons generated by the cavity’s heat. In Dark SRF, the cavities’ cold 1.4-kelvin temperature helps reduce the background to a mere 1,000 in the receiving cavity. Researchers plan to modify the system in the future to operate at about 6 millikelvins, winnowing the number to less than one on average and providing the opportunity to search for a more elusive version of the dark photon.

    “If you want to hunt for one photon, we are the only place in the world where you can do that with a cavity,” Grassellino said.

    Blue sky science for the dark world.

    The Dark SRF experiment is an example of how technology and expertise developed for a particular purpose — designing efficient particle accelerators — finds use in another pursuit — searching for hidden particles.

    Since it began operation in 2019, scientists on the Dark SRF Experiment have already made significant progress in their search. They’ve experimentally ruled out values for a particular quantity, called a kinetic mixing, that would point to the existence of a dark photon of a certain mass range (between 10 billionths and hundreds of millionths of an electronvolt). This narrows the possible values of the kinetic mixing by a factor of 1,000 compared to previous searches. Now they are pushing at the boundary of the parameter measurement by repeating the experiment using advanced quantum techniques.

    If the experiment does find evidence of dark photons, it will introduce a whole world of new questions to be explored: How common are dark photons in the universe? Are dark photons the dark matter scientists have been eagerly searching for? Do dark photons interact with other dark matter similar to how photons do with regular matter? If so, do they reveal another part of our universe as complex as our own but previously invisible?

    Whether the Dark SRF experiment discovers the dark photon or not, it will contribute to our understanding of the dark matter that we know is there but have yet to see.

    “The path forward follows what we all learnt at school: In science we make a hypothesis, we test it.” Harnik said. “If we find it, ‘Hooray!’ If we don’t find it — science progressed.”

    This work is supported by the DOE Office of Science.

    See the full here.


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    FNAL Icon

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

     
  • richardmitnick 4:28 pm on March 13, 2020 Permalink | Reply
    Tags: ANNIE Phase II Detector, , FNAL, ,   

    From Fermi National Accelerator Lab: “Innovative ANNIE sees first neutrinos, with more ‘firsts’ to come” 

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

    From Fermi National Accelerator Lab , an enduring source of strength for the US contribution to scientific research world wide.

    March 11, 2020
    Bob Svoboda

    The Accelerator Neutrino Neutron Interaction Experiment at Fermilab, known as ANNIE, has seen its first neutrino events.

    FNAL ANNIE Phase II Detector

    This milestone heralds the start of an ambitious program in neutrino physics and detector technology development. It is also a cause for celebration by the international ANNIE collaboration, composed of groups from Germany, the United Kingdom and the United States, who have been working diligently over the last two years to design and build the experiment.

    ANNIE has a list of “firsts” it plans to achieve: (1) the first accelerator experiment to use water doped with gadolinium to efficiently tag neutrons and (2) the first experiment to use new light-detection technology that can track particles with precision better than 100 trillionths of a second.

    The new sensors, called large-area picosecond photodetectors, or LAPPDs, were initially developed for particle physics, supported by funding from the Department of Energy’s Office of Science. Since then their development has also sparked interest in their use as a new commercial technology in a wide variety of fields, ranging from medicine to aerospace. ANNIE scientists hope that the use of these photodetectors will allow them to track neutrino events with unprecedented precision in an optical light detector, which would be a major advance in neutrino detector technology.

    ANNIE will also be able to try out other new technologies during its planned two-year run, including water-based liquid scintillator and wavelength-sensitive photodetectors, which are also being considered for next-generation experiments. Indeed, the trial of new technologies by ANNIE is expected to have an impact on the design of future neutrino detectors in general.

    The ANNIE detector sits in a 30-meter-deep underground hall on the Fermilab site (see illustration below). In the ANNIE design, neutrinos enter from the left and pass through the front veto, which rejects charged particles from neutrino events generated upstream. They then interact in the water volume to create an energetic muon (and possibly other charged particles). These charged particles make a characteristic Čerenkov light flash that is detected by the photosensors that line the wall, top, and bottom of the cylindrical water tank, which is about 3 meters in diameter and 4 meters high. This flash gives information on the neutrino interaction energy and also provides information on the muon direction — critical information for understanding the interaction. If the muon penetrates the full water volume it can enter the muon range detector, which tracks the muon and measures the energy deposited in the iron sandwich.

    2
    The ANNIE detector sits in an underground hall at Fermilab. The neutrino beam impinges from the left. The detector consists of three main elements: (1) a front veto to reject charged particles from neutrino events occurring upstream of the hall in the dirt, (2) an instrumented tank containing 25 tons of gadolinium loaded water to serve as both the neutrino target and neutron tagger, and (3) an iron and scintillator sandwich muon range detector to track and range out muons from the neutrino interactions in the target. Image: ANNIE collaboration.

    The ANNIE detector is currently being commissioned, and in January, it obtained its first neutrino events. In the image shown below, the cylindrical tank containing the doped water and array of photosensors — instruments that detect the neutrino interaction signal — is unfolded such that the sides of the tank appear as a large rectangle, while the circular top and bottom arrays are shown as circles. Each filled color circle represents a photosensor that was hit by Čerenkov light in time with the arrival of the pulsed neutrino beam, with the color scheme proportional to the amount of light (yellow is a high light level, purple is a low light level). The splash of light signals a muon from a neutrino interaction exiting the target volume. After the muon exited the tank it entered the muon range detector, where its track can be seen in the scintillator detectors in both the top and side views. The spaces between the scintillator detectors are filled with 2 inches of iron, and in this case, the muon was able to penetrate all the layers and exit the detector.

    This process takes only a few microseconds. The interesting and unique thing about ANNIE is what happens next. Neutrons can be created by the initial neutrino interaction. They can also be created by nuclear interactions in the struck oxygen nucleus (in the water) in a process that is not completely understood. These neutrons slow down and are captured on the gadolinium in the water tank over a much longer time period than the initial interaction (about 80 microseconds), allowing ANNIE to count the number of neutrons as a function of various neutrino interaction parameters to compare to model predictions. Currently, the gadolinium doping of the water is complete, and ANNIE is commissioning this unique part of its sensitivity with artificial-neutron-source deployments. ANNIE scientists expect to start efficiently detecting neutrons in coincidence with neutrino interactions very soon.

    4
    The cylindrical tank containing the doped water and photomultiplier tube array is shown unfolded: The sides of the tank appear as a large rectangle, and the circular top and bottom arrays are shown as circles. Each filled color circle represents a photosensor that was hit by Čerenkov light in time with a neutrino beam, with the color scheme proportional to the amount of light (yellow is a high light level, purple is a low light level). Image: ANNIE collaboration

    ANNIE’s pioneering accelerator neutrino measurements will contribute to understanding upcoming data from the Super-Kamiokande experiment in Japan, which is planning to add gadolinium to its water this spring.

    Super-Kamiokande experiment. located under Mount Ikeno near the city of Hida, Gifu Prefecture, Japan

    This is an excellent example of international scientific cooperation: the work done by the Super-Kamiokande collaboration in advance of their own gadolinium loading helped guide the design of ANNIE at Fermilab.

    This first observation of neutrinos in the ANNIE detector is expected to be followed by several thousands more over the next two years. Results from ANNIE will help physicists understand the role of nuclear effects in neutrino interactions – a topic that is also of critical interest to the international Deep Underground Neutrino Experiment, hosted by Fermilab.

    Congratulations to the ANNIE collaboration on reaching this first critical milestone!

    Bob Svoboda is a University of California, Davis, professor of physics and member of the ANNIE collaboration.

    U.S. support for the ANNIE collaboration is provided by DOE’s Office of Science and National Nuclear Security Administration. UK support is provided by UK Research & Innovation.

    See the full 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. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
    collaborate at Fermilab on experiments at the frontiers of discovery.

     
  • richardmitnick 7:05 pm on March 2, 2020 Permalink | Reply
    Tags: , FNAL, , It is well-established that the three known neutrino types – electron; muon; and tau – oscillate or change into one another., , , Searching for a fourth type of neutrino., What if the neutrinos are oscillating into a neutrino that does not interact at all- not even a little bit like other neutrinos do?   

    From Fermi National Accelerator Lab: “They are there and they are gone: ICARUS chases a fourth neutrino” 

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

    From Fermi National Accelerator Lab , an enduring source of strength for the US contribution to scientific research world wide.

    March 2, 2020
    Catherine N. Steffel

    FNAL/ICARUS

    2
    ICARUS – the largest particle detector in the lab’s Short-Baseline Neutrino Program – and filling it with 760 tons of liquid argon, moving ICARUS closer to operation and the search for a fourth type of neutrino. Photo: Al Johnson, Fermilab

    Argon. It’s all around us. It’s in the air we breathe, incandescent lights we read by and plasma globes many of us played with as children.

    In liquid form, argon is also an inexpensive and effective target for neutrino physics experiments. On Feb. 21, scientists at Fermilab began cooling down ICARUS – the largest particle detector in the lab’s Short-Baseline Neutrino Program – and filling it with 760 tons of liquid argon, moving ICARUS closer to operation and the search for a fourth type of neutrino.

    “The Short-Baseline Neutrino Program is amazing because it will finally resolve longstanding anomalous results in neutrino measurements,” said Robert Wilson, deputy spokesperson of ICARUS and professor of physics at Colorado State University.

    “Neutrinos are a fundamental and abundant component of our universe: We still know too little about them, and this keeps me very interested to continue searching their properties,” added Carlo Rubbia, Nobel laureate and ICARUS spokesperson.

    Over 20 years ago, scientists at Los Alamos National Laboratory found more electron antineutrinos than they expected in their results from the Liquid Scintillator Neutrino Detector. In a follow-up experiment more than 10 years later, scientists on the MiniBooNE experiment at Fermilab observed a similar inconsistency and uncovered a new anomaly in their neutrino data.

    Scientists wonder whether this was more than coincidence.

    A fourth type of neutrino

    It is well-established that the three known neutrino types – electron, muon and tau – oscillate, or change, into one another. To study these oscillations and how they happen, scientists need neutrinos to interact with something. For ICARUS, that substance is liquid argon.

    In the ICARUS experiment, a muon-type neutrino beam will interact with liquid argon and should, in theory, produce mostly charged particles called muons. (An electron-type neutrino beam should produce mostly electrons.) But given results from the Liquid Scintillator Neutrino Detector and MiniBooNE, this is only part of the story, and ICARUS intends to fill the gaps.

    “What if the neutrinos are oscillating into a neutrino that does not interact at all, not even a little bit like other neutrinos do?” Wilson said. “This is not a natural extension of neutrino theory, but it could explain the LSND and MiniBooNE results.”

    Such a fourth type of neutrino, unlike the others, would not change into a complementary charged particle upon interaction in a detector. In fact, it wouldn’t interact at all. By quantum mechanics, however, this so-called sterile neutrino could still oscillate between neutrino types and alter the oscillation pattern that ICARUS will observe.

    Discovery of a sterile neutrino would upend the Standard Model of subatomic particles and affect our understanding of how the universe has evolved.

    From filling to beam

    ICARUS’s optimal location, size and detector material make it uniquely sensitive to detecting neutrinos that would display this oscillation effect. If ICARUS scientists find more electron neutrinos in their muon-type neutrino beam than expected, they would at long last have concrete evidence of sterile neutrinos.

    ICARUS’s measurements will also inform how long-baseline neutrino experiments collect and analyze data. For example, scientists’ experience on ICARUS will inform the much larger, international Deep Underground Neutrino Experiment, hosted by Fermilab. ICARUS’s liquid-argon detection technology will be adapted for DUNE, which will use 70,000 tons of liquid argon to study the three known neutrino types and how they change from one to another.

    “ICARUS has come a long way from its conception and data taking activity at the Gran Sasso Laboratory in Italy and is now approaching an new phase of data acquisition here at Fermilab. I am thrilled to see the enthusiasm of a younger generation of scientists now at work on this experiment,” Rubbia said.

    It will take approximately eight weeks to fill ICARUS with liquid argon. Once the detector is filled, scientists will check its stability and the argon’s purity. Then, they will turn on power for the first time since ICARUS made its way to Fermilab across the Atlantic Ocean. They expect to see first particle tracks later this year.

    This work is supported by the U.S. Department of Energy Office of Science.

    See the full 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. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
    collaborate at Fermilab on experiments at the frontiers of discovery.

     
  • richardmitnick 9:25 am on February 28, 2020 Permalink | Reply
    Tags: "Particle accelerator technology could solve one of the most vexing problems in building quantum computers", , FNAL, , Quantum parallelism, Superconducting radio-frequency cavities, The decoherence of qubits   

    From Fermi National Accelerator Lab: “Particle accelerator technology could solve one of the most vexing problems in building quantum computers” 

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

    From Fermi National Accelerator Lab , an enduring source of strength for the US contribution to scientific research world wide.

    February 26, 2020
    Jerald Pinson

    1
    Superconducting radio-frequency cavities, such as the one seen here, are used in particle accelerators. They can also solve one of the biggest problems facing the successful development of a quantum computer: the decoherence of qubits. Photo: Reidar Hahn, Fermilab.

    Last year, researchers at Fermilab received over $3.5 million for projects that delve into the burgeoning field of quantum information science. Research funded by the grant runs the gamut, from building and modeling devices for possible use in the development of quantum computers to using ultracold atoms to look for dark matter.

    For their quantum computer project, Fermilab particle physicist Adam Lyon and computer scientist Jim Kowalkowski are collaborating with researchers at Argonne National Laboratory, where they’ll be running simulations on high-performance computers.

    Their work will help determine whether instruments called superconducting radio-frequency cavities, also used in particle accelerators, can solve one of the biggest problems facing the successful development of a quantum computer: the decoherence of qubits.

    “Fermilab has pioneered making superconducting cavities that can accelerate particles to an extremely high degree in a short amount of space,” said Lyon, one of the lead scientists on the project. “It turns out this is directly applicable to a qubit.”

    Researchers in the field have worked on developing successful quantum computing devices for the last several decades; so far, it’s been difficult. This is primarily because quantum computers have to maintain very stable conditions to keep qubits in a quantum state called superposition.

    Superposition

    Classical computers use a binary system of 0s and 1s – called bits – to store and analyze data. Eight bits combined make one byte of data, which can be strung together to encode even more information. (There are about 31.8 million bytes in the average three-minute digital song.) In contrast, quantum computers aren’t constrained by a strict binary system. Rather, they operate on a system of qubits, each of which can take on a continuous range of states during computation. Just as an electron orbiting an atomic nucleus doesn’t have a discrete location but rather occupies all positions in its orbit at once in an electron cloud, a qubit can be maintained in a superposition of both 0 and 1

    Since there are two possible states for any given qubit, a pair doubles the amount of information that can be manipulated: 22 = 4. Use four qubits, and that amount of information grows to 24 = 16. With this exponential increase, it would take only 300 entangled qubits to encode more information than there is matter in the universe.

    1
    Qubits can be in a superposition of 0 and 1, while classical bits can be only one or the other. Image: Jerald Pinson.

    Parallel positions

    Qubits don’t represent data in the same way as bits. Because qubits in superposition are both 0 and 1 at the same time, they can similarly represent all possible answers to a given problem simultaneously. This is called quantum parallelism, and it’s one of the properties that makes quantum computers so much faster than classical systems.

    The difference between classical computers and their quantum counterparts could be compared to a situation in which there is a book with some pages randomly printed in blue ink instead of black. The two computers are given the task of determining how many pages were printed in each color.

    “A classical computer would go through every page,” Lyon said. Each page would be marked, one at a time, as either being printed in black or in blue. “A quantum computer, instead of going through the pages sequentially, would go through them all at once.”

    Once the computation was complete, a classical computer would give you a definite, discrete answer. If the book had three pages printed in blue, that’s the answer you’d get.

    “But a quantum computer is inherently probabilistic,” Kowalkowski said.

    This means the data you get back isn’t definite. In a book with 100 pages, the data from a quantum computer wouldn’t be just three. It also could give you, for example, a 1 percent chance of having three blue pages or a 1 percent chance of 50 blue pages.

    An obvious problem arises when trying to interpret this data. A quantum computer can perform incredibly fast calculations using parallel qubits, but it spits out only probabilities, which, of course, isn’t very helpful – unless, that is, the right answer could somehow be given a higher probability.

    Interference

    Consider two water waves that approach each other. As they meet, they may constructively interfere, producing one wave with a higher crest. Or they may destructively interfere, canceling each other so that there’s no longer any wave to speak of. Qubit states can also act as waves, exhibiting the same patterns of interference, a property researchers can exploit to identify the most likely answer to the problem they’re given.

    “If you can set up interference between the right answers and the wrong answers, you can increase the likelihood that the right answers pop up more than the wrong answers,” Lyon said. “You’re trying to find a quantum way to make the correct answers constructively interfere and the wrong answers destructively interfere.”

    When a calculation is run on a quantum computer, the same calculation is run multiple times, and the qubits are allowed to interfere with one another. The result is a distribution curve in which the correct answer is the most frequent response.

    2
    When waves meet, they may constructively interfere, producing one wave with a higher crest. Image: Jerald Pinson.

    3
    Waves may also destructively interfere, canceling each other so that there’s no longer any wave to speak of. Image: Jerald Pinson.

    Listening for signals above the noise

    In the last five years, researchers at universities, government facilities and large companies have made encouraging advancements toward the development of a useful quantum computer. Last year, Google announced that it had performed calculations on their quantum processor called Sycamore in a fraction of the time it would have taken the world’s largest supercomputer to complete the same task.

    Yet the quantum devices that we have today are still prototypes, akin to the first large vacuum tube computers of the 1940s.

    “The machines we have now don’t scale up much at all,” Lyon said.

    There’s still a few hurdles researchers have to overcome before quantum computers become viable and competitive. One of the largest is finding a way to keep delicate qubit states isolated long enough for them to perform calculations.

    If a stray photon — a particle of light — from outside the system were to interact with a qubit, its wave would interfere with the qubit’s superposition, essentially turning the calculations into a jumbled mess – a process called decoherence. While the refrigerators do a moderately good job at keeping unwanted interactions to a minimum, they can do so only for a fraction of a second.

    “Quantum systems like to be isolated,” Lyon said, “and there’s just no easy way to do that.”

    4
    When a quantum computer is operating, it needs to be placed in a large refrigerator, like the one pictured here, to cool the device to less than a degree above absolute zero. This is done to keep energy from the surrounding environment from entering the machine. Photo: Reidar Hahn, Fermilab.

    Which is where Lyon and Kowalkowski’s simulation work comes in. If the qubits can’t be kept cold enough to maintain an entangled superposition of states, perhaps the devices themselves can be constructed in a way that makes them less susceptible to noise.

    It turns out that superconducting cavities made of niobium, normally used to propel particle beams in accelerators, could be the solution. These cavities need to be constructed very precisely and operate at very low temperatures to efficiently propagate the radio waves that accelerate particle beams. Researchers theorize that by placing quantum processors in these cavities, the qubits will be able to interact undisturbed for seconds rather than the current record of milliseconds, giving them enough time to perform complex calculations.

    Qubits come in several different varieties. They can be created by trapping ions within a magnetic field or by using nitrogen atoms surrounded by the carbon lattice formed naturally in crystals. The research at Fermilab and Argonne will be focused on qubits made from photons.

    Lyon and his team have taken on the job of simulating how well radio-frequency cavities are expected to perform. By carrying out their simulations on high-performance computers, known as HPCs, at Argonne National Laboratory, they can predict how long photon qubits can interact in this ultralow-noise environment and account for any unexpected interactions.

    Researchers around the world have used open-source software for desktop computers to simulate different applications of quantum mechanics, providing developers with blueprints for how to incorporate the results into technology. The scope of these programs, however, is limited by the amount of memory available on personal computers. In order to simulate the exponential scaling of multiple qubits, researchers have to use HPCs.

    “Going from one desktop to an HPC, you might be 10,000 times faster,” said Matthew Otten, a fellow at Argonne National Laboratory and collaborator on the project.

    Once the team has completed their simulations, the results will be used by Fermilab researchers to help improve and test the cavities for acting as computational devices.

    “If we set up a simulation framework, we can ask very targeted questions on the best way to store quantum information and the best way to manipulate it,” said Eric Holland, the deputy head of quantum technology at Fermilab. “We can use that to guide what we develop for quantum technologies.”

    This work is supported by the Department of Energy Office of Science.

    See the full here.


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    FNAL Icon

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

     
  • richardmitnick 6:16 pm on February 13, 2020 Permalink | Reply
    Tags: , FNAL, , ,   

    From Fermi National Accelerator Lab: “Finding hidden neutrinos with MicroBooNE” 

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

    From Fermi National Accelerator Lab , an enduring source of strength for the US contribution to scientific research world wide.

    February 13, 2020
    Owen Goodwin
    Davide Porzio
    Stefan Söldner-Rembold
    Yun-Tse Tsai

    Neutrinos have baffled scientists for decades as their properties and behavior differ from those of other known elementary particles. Their masses, for example, are much smaller than the masses measured for any other elementary matter particle we know. They also carry no electric charge and interact only very rarely – through the weak force — with matter. At Fermilab, a chain of accelerators generates neutrino beams so researchers can study neutrino properties and understand their role in the formation of the universe.

    Scientists working on Fermilab’s MicroBooNE experiment have published a paper [Physical Review D] describing a search for a new – hidden – type of heavier neutrino that could help explain why the masses of ordinary neutrinos are so small. It could also provide important clues about the nature of dark matter. This search is the first of its kind performed with a type of particle detector known as a liquid-argon time projection chamber.

    The MicroBooNE detector consists of a large tank of liquid argon [below], totaling 170 tons, located in an intense beam of neutrinos at Fermilab. The neutrinos originate in a beam produced by the lab’s accelerators. Some of these ordinary neutrinos will hit an argon nucleus in the tank, resulting in the production of other particles. The MicroBooNE detector then acts like a giant camera that records the particles produced in this collision.

    A heavier type of neutrino – which has been hypothesized but never observed – could also be produced in the accelerator-generated beam. These heavier types of neutrinos, scientifically called “heavy neutral leptons,” would not interact through the weak force and therefore could not hit an argon nucleus in the same way as ordinary neutrinos do. They could, however, leave a hint of their existence if they decayed into known particles inside the MicroBooNE detector.

    1
    The display shows the decay of a heavy neutrino as it would be measured in the MicroBooNE detector. Scientists use such simulations to understand what a signal in data would look like. Image: MicroBooNE collaboration

    To find such signatures of heavy neutrinos, MicroBooNE scientists devised a new method that helps them distinguish the heavy neutrino decays from ordinary neutrino scatterings on argon, and it has a lot to do with timing.

    The Fermilab neutrino beam is not a continuous stream of particles. Rather, it is pulsed, and the experimenters know when these neutrino pulses are supposed to arrive at the MicroBooNE detector: The heavy neutrinos would be more massive and therefore slower than the ordinary neutrinos – a well-tested prediction of special relativity. The trick is therefore to wait just long enough — until the ordinary neutrinos in a pulse have passed through and only heavy neutrinos could arrive.

    In the MicroBooNE detector, a heavy neutrino would appear to come out of nowhere. The only traces of its appearance would be tracks from two charged particles emerging from its decay – a muon and a pion (see figure). Using the measured angles and energies of these two daughter particles, the mass of the invisible parent particle – assumed to be the heavy neutrino — can be calculated.

    After sifting through all the MicroBooNE data, scientists found that only a handful of heavy-neutrino candidates remained. Scientists found that the origin of these candidates is consistent with being muons from cosmic rays constantly bombarding the MicroBooNE detector. In very rare cases, such a muon can mimic the two charged particles from a heavy neutral lepton.

    The heavy neutrinos – if they exist – are therefore still hiding. MicroBooNE’s results are expressed as a limit on the strength of the coupling – or mixing – of the hidden neutrinos with ordinary neutrinos. In this way, the sensitivity of the MicroBooNE detector can be translated into stringent constraints on models that predict hidden neutrino states, leading to better predictions. The short-baseline liquid-argon neutrino experiments at Fermilab are going to collect much more data in the coming years. Heavy neutrinos might not be able to hide much longer.

    See the full article here.


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    FNAL Icon

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

    FNAL MINERvA front face Photo Reidar Hahn

    FNAL DAMIC

    FNAL Muon g-2 studio

    FNAL Short-Baseline Near Detector under construction

    FNAL Mu2e solenoid

    Dark Energy Camera [DECam], built at FNAL

    FNAL DUNE Argon tank at SURF

    FNAL/MicrobooNE

    FNAL Don Lincoln

    FNAL/MINOS

    FNAL Cryomodule Testing Facility

    FNAL MINOS Far Detector in the Soudan Mine in northern Minnesota

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

    FNAL/NOvA experiment map

    FNAL NOvA Near Detector

    FNAL ICARUS

    FNAL Holometer

     
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