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  • richardmitnick 1:15 pm on March 30, 2021 Permalink | Reply
    Tags: "The mystery of the muon’s magnetism", , BNL-Brookhaven National Lab, , , , , ,   

    From Symmetry: “The mystery of the muon’s magnetism” 

    Symmetry Mag
    From Symmetry

    03/30/21
    Brianna Barbu

    A super-precise experiment at DOE’s Fermi National Accelerator Laboratory(US) is carefully analyzing every detail of the muon’s magnetic moment.

    1

    Modern physics is full of the sort of twisty, puzzle-within-a-puzzle plots you’d find in a classic detective story: Both physicists and detectives must carefully separate important clues from unrelated information. Both physicists and detectives must sometimes push beyond the obvious explanation to fully reveal what’s going on.

    And for both physicists and detectives, momentous discoveries can hinge upon Sherlock Holmes-level deductions based on evidence that is easy to overlook. Case in point: the Muon g-2 experiment currently underway at the US Department of Energy’s Fermi National Accelerator Laboratory.

    The current Muon g-2 (pronounced g minus two) experiment is actually a sequel, an experiment designed to reexamine a slight discrepancy between theory and the results from an earlier experiment at DOE’s Brookhaven National Laboratory(US), which was also called Muon g-2.

    DOE’s Fermi National Accelerator Laboratory(US) G-2 magnet from DOE’s Brookhaven National Laboratory(US) finds a new home in the FNAL Muon G-2 experiment. The move by barge and truck.

    Fermi National Accelerator Laboratory(US) Muon g-2 studio. As muons race around a ring at the , their spin axes twirl, reflecting the influence of unseen particles.

    The discrepancy could be a sign that new physics is afoot. Scientists want to know whether the measurement holds up… or if it’s nothing but a red herring.

    The Fermilab Muon g-2 collaboration has announced it will present its first result on April 7. Until then, let’s unpack the facts of the case.

    The mysterious magnetic moment

    All spinning, charged objects—including muons and their better-known particle siblings, electrons—generate their own magnetic fields. The strength of a particle’s magnetic field is referred to as its “magnetic moment” or its “g-factor.” (That’s what the “g” part of “g-2” refers to.)

    To understand the “-2” part of “g-2,” we have to travel a bit back in time.

    Spectroscopy experiments in the 1920s (before the discovery of muons in 1936) revealed that the electron has an intrinsic spin and a magnetic moment. The value of that magnetic moment, g, was found experimentally to be 2. As for why that was the value—that mystery was soon solved using the new but fast-growing field of quantum mechanics.

    In 1928, physicist Paul Dirac—building upon the work of Llewelyn Thomas and others—produced a now-famous equation that combined quantum mechanics and special relativity to accurately describe the motion and electromagnetic interactions of electrons and all other particles with the same spin quantum number. The Dirac equation, which incorporated spin as a fundamental part of the theory, predicted that g should be equal to 2, exactly what scientists had measured at the time.

    The Dirac equation in the form originally proposed by Dirac is

    4

    But as experiments became more precise in the 1940s, new evidence came to light that reopened the case and led to surprising new insights about the quantum realm.

    3
    Credit: Sandbox Studio, Chicago with Steve Shanabruch.

    A conspiracy of particles

    The electron, it turned out, had a little bit of extra magnetism that Dirac’s equation didn’t account for. That extra magnetism, mathematically expressed as “g-2” (or the amount that g differs from Dirac’s prediction), is known as the “anomalous magnetic moment.” For a while, scientists didn’t know what caused it.

    If this were a murder mystery, the anomalous magnetic moment would be sort of like an extra fingerprint of unknown provenance on a knife used to stab a victim—a small but suspicious detail that warrants further investigation and could unveil a whole new dimension of the story.

    Physicist Julian Schwinger explained the anomaly in 1947 by theorizing that the electron could emit and then reabsorb a “virtual photon.” The fleeting interaction would slightly boost the electron’s internal magnetism by a tenth of a percent, the amount needed to bring the predicted value into line with the experimental evidence. But the photon isn’t the only accomplice.

    Over time, researchers discovered that there was an extensive network of “virtual particles” constantly popping in and out of existence from the quantum vacuum. That’s what had been messing with the electron’s little spinning magnet.

    The anomalous magnetic moment represents the simultaneous combined influence of every possible effect of those ephemeral quantum conspirators on the electron. Some interactions are more likely to occur, or are more strongly felt than others, and they therefore make a larger contribution. But every particle and force in the Standard Model takes part.

    The theoretical models that describe these virtual interactions have been quite successful in describing the magnetism of electrons. For the electron’s g-2, theoretical calculations are now in such close agreement with the experimental value that it’s like measuring the circumference of the Earth with an accuracy smaller than the width of a single human hair.

    All of the evidence points to quantum mischief perpetrated by known particles causing any magnetic anomalies. Case closed, right?

    Not quite. It’s now time to hear the muon’s side of the story.

    Not a hair out of place—or is there?

    Early measurements of the muon’s anomalous magnetic moment at Columbia University (US) in the 1950s and at the European physics laboratory CERN [European Organization for Nuclear Research (Organisation européenne pour la recherche nucléaire)(EU)] in the 1960s and 1970s agreed well with theoretical predictions. The measurement’s uncertainty shrank from 2% in 1961 to 0.0007% in 1979. It looked as if the same conspiracy of particles that affected the electron’s g-2 were responsible for the magnetic moment of the muon as well.

    But then, in 2001, the Brookhaven Muon g-2 experiment turned up something strange. The experiment was designed to increase the precision from the CERN measurements and look at the weak interaction’s contribution to the anomaly. It succeeded in shrinking the error bars to half a part per million. But it also showed a tiny discrepancy—less than 3 parts per million—between the new measurement and the theoretical value. This time, theorists couldn’t come up with a way to recalculate their models to explain it. Nothing in the Standard Model could account for the difference.

    It was the physics mystery equivalent of a single hair found at a crime scene with DNA that didn’t seem to match anyone connected to the case. The question was—and still is—whether the presence of the hair is just a coincidence, or whether it is actually an important clue.

    Physicists are now re-examining this “hair” at Fermilab, with support from the DOE Office of Science (US), the National Science Foundation (US) and several international agencies in Italy, the UK, the EU, China, Korea and Germany.

    In the new Muon g-2 experiment, a beam of muons—their spins all pointing the same direction—are shot into a type of accelerator called a storage ring. The ring’s strong magnetic field keeps the muons on a well-defined circular path. If g were exactly 2, then the muons’ spins would follow their momentum exactly. But, because of the anomalous magnetic moment, the muons have a slight additional wobble in the rotation of their spins.

    When a muon decays into an electron and two neutrinos, the electron tends to shoot off in the direction that the muon’s spin was pointing. Detectors on the inside of the ring pick up a portion of the electrons flung by muons experiencing the wobble. Recording the numbers and energies of electrons they detect over time will tell researchers how much the muon spin has rotated.

    Using the same magnet from the Brookhaven experiment with significantly better instrumentation, plus a more intense beam of muons produced by Fermilab’s accelerator complex, researchers are collecting 21 times more data to achieve four times greater precision.

    The experiment may confirm the existence of the discrepancy; it may find no discrepancy at all, pointing to a problem with the Brookhaven result; or it may find something in between, leaving the case unsolved.

    Seeking the quantum underworld

    There’s reason to believe something is going on that the Standard Model hasn’t told us about.

    The Standard Model is a remarkably consistent explanation for pretty much everything that goes on in the subatomic world.

    Standard Model of Particle Physics from “Particle Fever” via Symmetry Magazine

    But there are still a number of unsolved mysteries in physics that it doesn’t address.

    Dark matter, for instance, makes up about 27% of the universe. And yet, scientists still have no idea what it’s made of. None of the known particles seem to fit the bill. The Standard Model also can’t explain the mass of the Higgs boson, which is surprisingly small. If the Fermilab Muon g-2 experiment determines that something beyond the Standard Model—for example an unknown particle—is measurably messing with the muon’s magnetic moment, it may point researchers in the right direction to close another one of these open files.

    A confirmed discrepancy won’t actually provide DNA-level details about what particle or force is making its presence known, but it will help narrow down the ranges of mass and interaction strength in which future experiments are most likely to find something new. Even if the discrepancy fades, the data will still be useful for deciding where to look.

    It might be that a shadowy quantum figure lurking beyond the Standard Model is too well hidden for current technology to detect. But if it’s not, physicists will leave no stone unturned and no speck of evidence un-analyzed until they crack the case.

    See the full article here .


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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 5:11 pm on November 13, 2020 Permalink | Reply
    Tags: "US Takes an Important Step Toward Quantum Internet", A new kind of computing needs a new kind of internet., , BNL-Brookhaven National Lab, , Quantum bits- or qubits- from two distant quantum computers can be entangled in a third location., , Stony Brook University, , The actual quantum internet is going to be a collection of solid-state-based quantum computers like the ones in Chicago and atomic-based quantum computers like the ones we have here in New York., The last obstacle is far more distant in a future where the New York quantum network is connected to the one being built by Argonne National Laboratory and the University of Chicago., The recent experiment is essentially half of a quantum repeater., The researchers did it over standard internet cables., This reliance on traditional internet means that the endeavor to build a quantum internet is very interdisciplinary., We have to find a way to connect all of them to really come out with a first prototype of the quantum internet., You cannot build a quantum network and be successful without a classical network., You have to control manage and synchronize the quantum devices over the classical network to really transmit information between the two ends of a quantum network.   

    From Inside Science: “US Takes an Important Step Toward Quantum Internet” 

    From Inside Science

    November 12, 2020
    Meredith Fore

    A recent experiment has created a one-way quantum network between two labs, reaching a milestone on the path to creating a quantum internet.

    1
    Credit: Dmitriy Rybin via Shutterstock.

    While researchers continue to make quantum computers increasingly capable, regular computers still hold a massive advantage: Their data, represented in sequences of zeros and ones, can ride the information superhighway. Quantum computers, which instead run on quantum superpositions of zeros and ones, can’t use the internet to communicate with each other.

    Multiple projects across the world are working to create a “quantum internet,” a network where quantum computers can share and exchange information. One such project, a collaboration between Brookhaven National Lab and Stony Brook University in New York, recently hit a major milestone: demonstrating that quantum bits, or qubits, from two distant quantum computers can be entangled in a third location.

    This is a critical step in creating a quantum internet, and significantly, the researchers did it over standard internet cables.

    “Part of the challenge of building a quantum internet is, to what extent can I even get quantum information through the kinds of fiber networks that we use for normal communications?” said Joseph Lykken, deputy director of research at Fermi National Accelerator Laboratory and head of the Fermilab Quantum Institute. “That’s really important, and they’re doing this at a longer distance at Brookhaven-Stony Brook than I think almost anybody else.”

    A new kind of computing needs a new kind of internet.

    Quantum computers aren’t superpowerful versions of classical computers. Instead, they approach computing in a whole new way. They can theoretically take advantage of quantum mechanical concepts such as superposition and entanglement to solve certain types of problems — for example, ones that show up when encrypting data or simulating chemical reactions — much faster than traditional approaches. Quantum computing technology is still in the early stages of development, and many of the most promising applications remain unrealized. Other applications may have yet to be discovered.

    Similarly, the “quantum internet” will not be a superfast and secure version of today’s internet. Instead, it will likely have particular applications transferring quantum information between computers. To do this, the computers’ qubits are entangled, meaning they are put in a superposition in which their separate possible quantum states become dependent on each other and the qubits then become a single quantum system. Measuring the state of one of these qubits breaks the superposition, immediately influencing the state of the others — and this measurement/entanglement process is how quantum information can be transmitted.

    Entanglement between two quantum computers has been experimentally possible for several years, but the team at Brookhaven and Stony Brook has gone one step further: They have created the longest quantum network in the United States by showing that two quantum computers can be entangled using a third node. This is the first step in building a network where many computers can “talk” to each other through a central node.

    To do the experiment, the researchers faced a challenge unique to quantum systems: In order to entangle quantum particles, which make up qubits, the particles must arrive at the node completely indistinguishable from one another even though they took different paths to get there. The more different the path, the more difficult this is — and the network between Brookhaven and Stony Brook runs over traditional fiber-optic cables that are miles long, going under the neighborhoods and highways of Long Island.

    “It’s not really feasible to lay new cables everywhere, so being able to use what’s in the ground was important,” said Kerstin Kleese Van Dam, the director of Brookhaven’s Computational Science Initiative.

    Any unexpected interaction between one of the transmitted quantum particles and its environment might have made it distinguishable from the other. But despite all the potential sources of interference, the experiment was able to prove that the particles could travel over 70 kilometers (almost 45 miles) over traditional infrastructure and still arrive indistinguishable.

    “Our results demonstrate that these photons can be entangled, that the measurement will work,” said Eden Figueroa, a quantum physicist at Stony Brook University and lead scientist of the project.

    The recent experiment was one-way: The quantum computers sent their qubits to the node, but the node simply determined whether they could be entangled and didn’t send anything back. The next step, Figueroa said, is to entangle the computers’ quantum memories, which would be analogous to linking two traditional computers’ hard drives.

    “Down the line we hope that instead of just memories, we will be entangling computers — not just connecting the hard drives but also the processing units,” Figueroa said. “Of course, that’s not easy.”

    How far away is the quantum internet?

    The remaining obstacles to a quantum internet are a blend of research questions and infrastructure concerns. One issue is that manipulating qubits between quantum computers requires synchronization and supervision in a way that the management of traditional bits doesn’t. This means that while quantum computers can’t directly exchange quantum information over the internet, they still need conventional computers that do use the internet to communicate.

    “You cannot build a quantum network and be successful without a classical network,” said Inder Monga, the director of the Energy Sciences Network, which provides networking services to all U.S. national labs. “You have to control, manage and synchronize the quantum devices over the classical network to really transmit information between the two ends of a quantum network.”

    This reliance on traditional internet means that the endeavor to build a quantum internet is very interdisciplinary, Monga and Figueroa said. It requires expertise in basic quantum computing research as well as communication infrastructure engineering.

    “There are as many research problems as are engineering problems,” Monga said, “and to really get to the vision of the quantum internet, it will require a strong collaboration between people and funding to solve not just the basic physics research problems but also the really grand engineering challenges as well.”

    A central obstacle to the quantum internet is what Figueroa calls “the holy grail of quantum communication”: a quantum repeater. A quantum repeater works like an amplifier, in that it receives a signal of quantum information and passes it on so that entanglement between computers can happen at a greater distance. This is necessary to make a quantum internet that spreads beyond Long Island. But there’s a catch: Any interaction with a qubit breaks its superposition — and for information to be transmitted, that can’t happen until the qubit reaches its destination. A true quantum repeater would be able to amplify a qubit without interacting with it, a seemingly paradoxical task.

    The recent experiment is essentially half of a quantum repeater. Kleese Van Dam and Figueroa see a completed quantum repeater in the near future: possibly as soon as 2022, Figueroa said. They plan to transmit entanglement to a third lab in Brooklyn but need a quantum repeater to do so.

    “We hope that in a few years, we might actually have a working system with repeaters,” Figueroa said. “The minute we can demonstrate that quantum repeater connection, you just need to reproduce the same architecture, again and again, to connect places that are more and more distant from each other.” He sees a network across New York state in 10-15 years.

    The last obstacle is far more distant, in a future where the New York quantum network is connected to the one being built by Argonne National Laboratory and the University of Chicago, or the one being built in Europe. Those networks are built using fundamentally different quantum computers — while the New York network uses computers whose qubits are embedded in single trapped atoms, the other networks use what are called solid-state systems to make and manipulate qubits. The two kinds of quantum computers perform computation with completely different architecture.

    “You can imagine that the actual quantum internet is going to be a collection of solid-state-based quantum computers like the ones in Chicago and atomic-based quantum computers like the ones we have here, and we have to find a way to connect all of them to really come out with a first prototype of the quantum internet,” Figueroa said. “That would be very cool. That would be like science fiction.”

    In July 2020, the U.S. Department of Energy released a “blueprint” of their strategy to create a national quantum internet. This effort includes the Brookhaven-Stony Brook project and the Argonne-University of Chicago project, which are in turn both supported by research at other national labs such as Fermi National Accelerator Laboratory, and Lawrence Berkeley, Oak Ridge, and Los Alamos National Laboratories.

    “While quantum computing has gotten a lot of press and funding, the wave is going toward quantum networking,” Figueroa said, “because unless you connect quantum computers into this quantum internet, their applications will be limited. So, it is a good time to be doing these kinds of experiments.”

    See the full article here .

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    Inside Science is brought to you in part through the generous support of The American Physical Society and The Acoustical Society of America and a coalition of underwriters.

     
  • richardmitnick 2:13 pm on October 20, 2020 Permalink | Reply
    Tags: , BNL-Brookhaven National Lab, , , ,   

    From Symmetry: “The many paths of muon math” 

    Symmetry Mag
    From Symmetry<

    10/20/20
    Daniel Garisto

    1
    Illustration by Sandbox Studio, Chicago with Ariel Davis.

    Here’s how physicists calculate g-2, the value that will determine whether the muon is giving us a sign of new physics.

    Like racecars on a track, thousands of particles called muons zip around an experiment’s giant 50-foot circular magnet at 99.9% of the speed of light. After making a few hundred laps in less than a millisecond, the muons decay and are soon replaced by another bunch.

    FNAL Muon g-2 studio.

    The goal of the experiment, Fermilab Muon g-2, is to better understand the properties of muons, which are essentially heavier versions of electrons, and use them to probe the limitations of the Standard Model of particle physics. Specifically, physicists want to know about the muons’ “magnetic moment”—that is, how much do they rotate on their axes in a powerful magnetic field— as they race around the magnet?

    In 2001, an experiment at the US Department of Energy’s Brookhaven National Lab found that the muons turned more than theory predicted.

    Brookhaven Muon g-2 ring.

    FNAL G-2 magnet from Brookhaven Lab finds a new home in the FNAL Muon G-2 experiment.

    The result surprised the physics community: If there really were a discrepancy, it could be a hint of new physics, like some as-yet-unknown particle influencing the muon. Two decades later, physicists hope to resolve the matter. Fermilab Muon g-2 aims to quadruple the precision of the 2001 finding and determine whether experiment really disagrees with theory.

    There’s another side to the search though—one that’s carried out not with particle accelerators and giant magnets, but with equations on blackboards and computer simulations. Since 2016, another group of physicists has been trying to update the theoretical prediction of the muon’s magnetic moment by combining the efforts of several groups.

    In June, the Muon g-2 Theory Initiative, which comprises 132 physicists across 82 institutions, published its first prediction: They calculated the muon’s anomalous magnetic moment, or αµ, to be 116,591,810×10-11. The value differs subtly, but significantly from the 2001 experiment, which found αµ to be 116,592,089×10-11. (That’s a difference of 279 parts in a million, for those keeping score at home.)

    “This is the first time that the entire community has come together and reached a consensus on the Standard Model prediction of this quantity,” says Aida X. El-Khadra, a physicist at the University of Illinois Urbana-Champaign and cofounder of the Theory Initiative. Previously, individual groups produced their own predictions of αµ, which differed slightly from one another.

    By combining their efforts, physicists in the Theory Initiative hope that they’ll be able to come up with an ultra-precise prediction to complement the forthcoming result from the Fermilab Muon g-2 experiment. Both the experiment and the theory initiative receive support from DOE’s Office of Science.

    But just how do physicists predict something like the muon’s magnetic moment, and why does it take 132 of them?

    The path to g-2

    The first calculations of particle magnetic moments came in the 1920s, when physicists were just beginning to develop relativistic quantum mechanics. British theoretical physicist Paul Dirac, building on the work of Llewellyn Thomas and others, found the ultimate equation describing the electron and its spin—then conceived of as the electron’s internal rotation—and its magnetic moment. Dirac predicted this number, called “g,” to be exactly 2.

    But atomic spectroscopy experiments soon found that g differed from that prediction by about 0.1%—a so-called “anomalous” magnetic moment, αe. In 1947, Julian Schwinger developed a theoretical explanation: The electron could emit and then reabsorb a virtual photon, which slightly changed its interaction with a magnetic field.

    “Every way that something can happen in nature will happen,” says Tom Blum, a theoretical physicist at the University of Connecticut. “If a particle starts from here and gets to there, it can take all possible paths to get from there to there. And what quantum field theory tells us is how to weight those paths.”

    The emission and absorption of a single virtual photon is just the most straightforward of these possible particle paths. Since Schwinger, physicists have been working to calculate increasingly unlikely possible paths that a particle can take. Ironically, the way they think about these paths is with a tool of Schwinger’s rival, Richard Feynman. To illustrate the paths and calculate their probabilities, Feynman developed his eponymously named diagrams.

    Here, the Feynman diagram represents a muon (the Greek letter mu) moving left to right in a magnetic field (the squiggly line, which also denotes a photon).

    3

    The Feynman diagram for Schwinger’s path is slightly more complicated—this time there’s a squiggly blue line, the virtual photon being emitted and absorbed by the muon. This contributes approximately 0.00116 to αµ. This is the vast majority of muon’s anomalous magnetic moment.

    4

    To make the task manageable, the Theory Initiative segmented the task of calculating the muon’s magnetic moment into each component. To get down to a precision of about 100 parts in a billion, physicists have had to calculate a lot more than just a single virtual photon.

    “Contributions to the anomalous magnetic moment come from the three different interactions— the strong interaction, the weak interaction and quantum electrodynamics all contribute,” Blum says.

    There was at one point some thought that gravity would have an impact, but further investigation proved its role was too small.

    Quantum electrodynamics, or QED, covers all the possible ways a photon can interact with a muon. To get better precision, physicists can account for more virtual photons. Each additional virtual photon has about 1/137th the chance of being produced and reabsorbed, so a Feynman diagram with two virtual photons contributes about 1 / 137 * 137 to αµ, three virtual photons contribute 1 / 137 * 137 * 137, and so on. Physicists have even gone all the way to five virtual photons.

    With five virtual photons, there are more than 10,000 possible paths, so there are a corresponding number of Feynman diagrams to calculate. Possibilities abound because virtual photons can split into a virtual electron and a virtual positron (the antimatter counterpart to an electron). This virtual pair can then annihilate back into a virtual photon. Describing these complex paths requires loops and squiggles that arc over each other. Five-photon Feynman diagrams look less like a traditional particle physics schematic and more like abstract art.

    6

    The weak force and the strong force

    The weak force, which governs the radioactive decay of nuclei, also plays a role in influencing the muon’s magnetic moment. Unlike QED, which is mediated by the massless photon, the weak force is mediated by the massive W and Z bosons, which each weigh about 90 times the mass of a proton. The fact that the bosons are heavy makes it extremely unlikely that the muon would emit and absorb a virtual W or Z boson. But occasionally, it does happen.

    7

    Both QED and the contribution from the weak force can be calculated to extremely high precision. The process is arduous, but physicists can calculate a good deal of the interactions simply by hand. That’s not the case with contributions from particles bound together by the strong force called hadrons, which represent the majority of uncertainty in the calculation of the muon’s anomalous magnetic moment.

    Gluons, the particles that mediate the strong force, are described by the rules of quantum chromodynamics, or QCD. Unlike photons in QED, gluons can interact with one another. Trying to calculate QCD processes by hand is effectively impossible, because the self-interacting gluons throw everything out of whack.

    “The reason why we need a collaborative effort is because the hadronic corrections cannot be calculated from first principle QCD on a blackboard,” says El-Khadra.

    There are two main types of hadronic corrections: “vacuum polarization” corrections and “light by light” corrections. In vacuum polarization, the muon emits a virtual photon, which decays into a quark and antiquark. These quarks and antiquarks exchange gluons, turning into a frothing blob of hadronic matter such as pions and kaons. Finally, the virtual blob of hadronic matter ends when a quark and antiquark annihilate back into a virtual photon, which is finally absorbed by the muon.

    8

    Light by light contributions are perhaps some of the strangest. From the outside, it looks as if two virtual photons are emitted by a muon, interact, and are then absorbed. What’s going on here?

    “When we look around us… the reason why we can see very well is because photons—to a large degree—don’t interact with each other,” says Christoph Lehner, a physicist at Brookhaven National Lab and cofounder of the Theory Initiative.

    But if the two virtual photons get caught in a quark loop, each converting to a virtual quark and virtual antiquark, they can form a blob of hadronic matter. If the virtual quarks and virtual antiquarks annihilate back into virtual photons, the two will appear to have bounced off of one another, interacting in a forbidden way.

    Traditionally, hadronic corrections to αµ were calculated using so-called “dispersion relations.” Physicists modeling the virtual blob of hadronic matter would turn to experiments where real blobs of hadronic matter were created. Real blobs are produced in experiments where electrons collide with positrons, creating a spray of hadronic matter. Experiments like BaBar, KLOE and now Belle II all provide this kind of data, which physicists have scoured to better understand the virtual blobs.

    A contribution from supercomputing

    Recently, another method for calculating messy hadronic blobs has become viable, thanks to increasingly powerful computers and improved algorithms. Lattice QCD is a method for essentially simulating the blob from the ground up. Physicists write in the properties of the particles and the forces that govern them, set up a giant sandbox (a lattice) that the system can evolve in, and let it run. Lattice QCD is hugely computationally intensive—to produce a precise simulation, supercomputers have to calculate all of the gluon interchanges, a task that was impossible by hand.

    Because it’s a simulation of the real world from first principles, “it’s in that sense very similar to an experiment,” according to Lehner.

    One benefit is that physicists can be confident that their approach provides an answer to the question. The downsides, as in any experiment, are systematic errors—and the amount of resources required. Finding computer time is easier said than done, but at the end of the day, lattice QCD is approaching the precision of the dispersion relation method.

    Contribution—————————————–Value (x10-11)
    QED ———————————————116,584,718.931±.104
    Weak force——————————————-153.6±1.0
    Hadronic vacuum polarization (dispersive)————6,845±40
    NOT USED (Lattice hadronic vacuum polarization)——7116±184
    Hadronic light-by-light (dispersive+lattice)———92±18
    Total Standard Model Value ————————–116,591,810±43
    Difference from 2001 experiment———————-279±76

    Putting it all together

    In February, a lattice QCD group claimed to have a result for hadronic contributions in serious conflict with the predictions of dispersive relations. Almost immediately, a flurry of other publications discussing and challenging the result followed. The June paper from the Theory Initiative does not address the potential inconsistency, but lattice QCD researchers are hard at work trying to replicate the result.

    At the end of the day, when the experimentalists finish analyzing the data from the Muon g-2 experiment, they’ll compare against the theoretical value to see if there’s still a significant discrepancy. The hope, for many, is that they continue to disagree, opening a window for new physics.

    See the full article here .


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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 8:50 am on September 11, 2020 Permalink | Reply
    Tags: "Quirky Response to Magnetism Presents Quantum Physics Mystery", , BNL-Brookhaven National Lab, , Magnetic topological insulators could be just right for making qubits but this one doesn't obey the rules., , ,   

    From Brookhaven National Lab: “Quirky Response to Magnetism Presents Quantum Physics Mystery” 

    From Brookhaven National Lab

    September 10, 2020
    Karen McNulty Walsh
    kmcnulty@bnl.gov
    (631) 344-8350

    Peter Genzer
    genzer@bnl.gov
    (631) 344-3174

    Magnetic topological insulators could be just right for making qubits, but this one doesn’t obey the rules.

    1
    Schematic diagram showing both the magnetism and the conductive behavior on the surface of MnBi2Te4. The magnetism points uniformly upward, as shown by the red arrows, and the surface electrons, represented by the hourglass structures, are conductive because the top and bottom halves touch at the vertex with no ‘gap’ in the middle (see text). Both of these features are not expected to occur simultaneously, illustrating the need to further understand the material’s fundamental properties.

    The search is on to discover new states of matter, and possibly new ways of encoding, manipulating, and transporting information. One goal is to harness materials’ quantum properties for communications that go beyond what’s possible with conventional electronics. Topological insulators—materials that act mostly as insulators but carry electric current across their surface—provide some tantalizing possibilities.

    “Exploring the complexity of topological materials—along with other intriguing emergent phenomena such as magnetism and superconductivity—is one of the most exciting and challenging areas of focus for the materials science community at the U.S. Department of Energy’s Brookhaven National Laboratory,” said Peter Johnson, a senior physicist in the Condensed Matter Physics & Materials Science Division at Brookhaven. “We’re trying to understand these topological insulators because they have lots of potential applications, particularly in quantum information science, an important new area for the division.”

    For example, materials with this split insulator/conductor personality exhibit a separation in the energy signatures of their surface electrons with opposite “spin.” This quantum property could potentially be harnessed in “spintronic” devices for encoding and transporting information. Going one step further, coupling these electrons with magnetism can lead to novel and exciting phenomena.

    “When you have magnetism near the surface you can have these other exotic states of matter that arise from the coupling of the topological insulator with the magnetism,” said Dan Nevola, a postdoctoral fellow working with Johnson. “If we can find topological insulators with their own intrinsic magnetism, we should be able to efficiently transport electrons of a particular spin in a particular direction.”

    In a new study just published and highlighted as an Editor’s Suggestion in Physical Review Letters, Nevola, Johnson, and their coauthors describe the quirky behavior of one such magnetic topological insulator. The paper includes experimental evidence that intrinsic magnetism in the bulk of manganese bismuth telluride (MnBi2Te4) also extends to the electrons on its electrically conductive surface. Previous studies had been inconclusive as to whether or not the surface magnetism existed.

    But when the physicists measured the surface electrons’ sensitivity to magnetism, only one of two observed electronic states behaved as expected. Another surface state, which was expected to have a larger response, acted as if the magnetism wasn’t there.

    “Is the magnetism different at the surface? Or is there something exotic that we just don’t understand?” Nevola said.

    Johnson leans toward the exotic physics explanation: “Dan did this very careful experiment, which enabled him to look at the activity in the surface region and identify two different electronic states on that surface, one that might exist on any metallic surface and one that reflected the topological properties of the material,” he said. “The former was sensitive to the magnetism, which proves that the magnetism does indeed exist in the surface. However, the other one that we expected to be more sensitive had no sensitivity at all. So, there must be some exotic physics going on!”

    The measurements

    The scientists studied the material using various types of photoemission spectroscopy, where light from an ultraviolet laser pulse knocks electrons loose from the surface of the material and into a detector for measurement.

    “For one of our experiments, we use an additional infrared laser pulse to give the sample a little kick to move some of the electrons around prior to doing the measurement,” Nevola explained. “It takes some of the electrons and kicks them [up in energy] to become conducting electrons. Then, in very, very short timescales—picoseconds—you do the measurement to look at how the electronic states have changed in response.”

    The map of the energy levels of the excited electrons shows two distinct surface bands that each display separate branches, electrons in each branch having opposite spin. Both bands, each representing one of the two electronic states, were expected to respond to the presence of magnetism.

    To test whether these surface electrons were indeed sensitive to magnetism, the scientists cooled the sample to 25 Kelvin, allowing its intrinsic magnetism to emerge. However only in the non-topological electronic state did they observe a “gap” opening up in the anticipated part of the spectrum.

    “Within such gaps, electrons are prohibited from existing, and thus their disappearance from that part of the spectrum represents the signature of the gap,” Nevola said.

    The observation of a gap appearing in the regular surface state was definitive evidence of magnetic sensitivity—and evidence that the magnetism intrinsic in the bulk of this particular material extends to its surface electrons.

    However, the “topological” electronic state the scientists studied showed no such sensitivity to magnetism—no gap.

    “That throws in a bit of a question mark,” Johnson said.

    “These are properties we’d like to be able to understand and engineer, much like we engineer the properties of semiconductors for a variety of technologies,” Johnson continued.

    In spintronics, for example, the idea is to use different spin states to encode information in the way positive and negative electric charges are presently used in semiconductor devices to encode the “bits”—1s and 0s—of computer code. But spin-coded quantum bits, or qubits, have many more possible states—not just two. This will greatly expand on the potential to encode information in new and powerful ways.

    “Everything about magnetic topological insulators looks like they’re right for this kind of technological application, but this particular material doesn’t quite obey the rules,” Johnson said.

    So now, as the team continues their search for new states of matter and further insights into the quantum world, there’s a new urgency to explain this particular material’s quirky quantum behavior.

    This work was funded by the DOE Office of Science.

    See the full article here .


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    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

     
  • richardmitnick 10:24 am on September 4, 2020 Permalink | Reply
    Tags: "Microwaving new materials", , BNL-Brookhaven National Lab, , , Jayan used x-ray pair distribution function (PDF) analysis., Microwaving tailor-made ceramic materials with new electronic thermal and mechanical properties., Reeja Jayan,   

    From Carnegie Mellon University and Brookhaven National Lab: Women in STEM- Reeja Jayan “Microwaving new materials” 


    From Carnegie Mellon University

    and

    From Brookhaven National Lab

    9.4.20
    Sherry Stokes

    1
    Reeja Jayan

    Reeja Jayan has made a breakthrough in our understanding of how microwaves affect materials chemistry, laying the groundwork for tailor-made ceramic materials with new electronic, thermal, and mechanical properties.

    Microwave ovens are the mainstay of cooking appliances in our homes. Five years ago, when Reeja Jayan was a new professor at Carnegie Mellon University, she was intrigued by the idea of using microwaves to grow materials. She and other researchers had shown that microwave radiation enabled temperature crystallization and growth of ceramic oxides. Exactly how microwaves did this was not well understood, and this mystery inspired Jayan to reengineer a $30 microwave oven so she could investigate the dynamics effects of microwave radiation on the growth of materials.

    2
    If you look carefully in the center of this photo, you will see the $30 microwave oven that Reeja Jayan reengineered to start her experiments.
    Source credit: Reeja Jayan.

    Today, Jayan, who is now an associate professor of mechanical engineering, has made a breakthrough in our understanding of how microwaves affect materials chemistry. She and her student Nathan Nakamura exposed tin oxide (a ceramic) to 2.45 GHz microwave radiation and figured out how to monitor (in situ) atomic structural changes as they occurred. This discovery is important because she demonstrated that microwaves affected the tin oxide’s oxygen sublattice via distortions introduced in the local atomic structure. Such distortions do not occur during conventional materials synthesis (where energy is directly applied as heat).

    Unlike prior studies, which suffered from the inability to monitor structural changes while the microwaves were applied, Jayan developed novel tools (a custom-designed microwave reactor enabling in-situ synchrotron x-ray scattering) for studying these dynamic, field-driven changes in local atomic structure as they happen. By revealing the dynamics of how microwaves affect specific chemical bonds during the synthesis, Jayan is laying the groundwork for tailor-made ceramic materials with new electronic, thermal, and mechanical properties.

    3
    In-situ PDF Data Collection: Waveguide installed at 28-ID-2 beamline at the National Synchrotron Light Source II, Brookhaven National Laboratory. The results in Jayan’s paper [below] came from the custom-built microwave reactor, which offers precise engineering controls. (Source: Reeja Jayan.)

    “Once we know the dynamics, we can use this knowledge to make materials that are far away from equilibrium, as well as devise new energy efficient processes for existing materials, such as 3D printing of ceramics,” she says. The commercialization of additive manufacturing of metals and plastics is widespread, but the same cannot be said for ceramic materials. 3D printing of ceramics could advance industries ranging from healthcare—imagine artificial bones and dental implants—to industrial tooling and electronics—ceramics can survive high temperatures that metals can’t. However, integrating ceramic materials with today’s 3D printing technologies is difficult because ceramics are brittle, ultrahigh temperatures are required, and we don’t understand how to control their properties during printing processes.

    Jayan’s findings were derived from unconventional experiments that relied on a combination of tools. She used x-ray pair distribution function (PDF) analysis to provide real-time, in situ structural information about tin oxide as it was being exposed to microwave radiation. She compared these results to tin oxide that was synthesized without electromagnetic field exposure. The comparisons revealed that the microwaves were influencing atomic-scale structure by disturbing the oxygen sublattice. “We were the first to prove that microwaves create such localized interactions by devising a method to watch them live during a chemical reaction,” says Jayan.

    4
    The custom-built microwave reactor was integrated into the X-ray Powder Diffraction (XPD) beamline located at the US Department of Energy Brookhaven National Laboratory. Source: US Department of Energy Brookhaven National Laboratory.

    These experiments were extremely difficult to conduct and required a custom-built microwave reactor. (This represented a significant upgrade in cost and engineering compared to the original domestic oven). The reactor was designed in collaboration with Gerling Applied Engineering, and the experiments were conducted at the US Department of Energy Brookhaven National Laboratory (BNL). Dr. Sanjit Ghose and Dr. Jianming Bai, lead scientists at BNL, were instrumental in helping Jayan’s team integrate the microwave reactor into the beamline.

    “Another takeaway from this research is that microwaves can do more than just heating. They can have a non-thermal effect, which can rearrange the structure of materials like a jigsaw puzzle,” says Jayan. Building on this concept, she is investigating how to use microwaves to engineer new materials.

    The results of Jayan’s research were published in the Journal of Materials Chemistry A. The paper was recognized as part of the 2020 Emerging Investigators Issue of the journal. Jayan’s work was supported by a Young Investigator grant from the U.S. Department of Defense, Air Force Office of Scientific Research.

    See the full article here .

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    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

    Carnegie Mellon University (CMU) is a global research university with more than 12,000 students, 95,000 alumni, and 5,000 faculty and staff.
    CMU has been a birthplace of innovation since its founding in 1900.
    Today, we are a global leader bringing groundbreaking ideas to market and creating successful startup businesses.
    Our award-winning faculty members are renowned for working closely with students to solve major scientific, technological and societal challenges. We put a strong emphasis on creating things—from art to robots. Our students are recruited by some of the world’s most innovative companies.
    We have campuses in Pittsburgh, Qatar and Silicon Valley, and degree-granting programs around the world, including Africa, Asia, Australia, Europe and Latin America.

     
  • richardmitnick 9:53 am on August 28, 2020 Permalink | Reply
    Tags: "Nuclear Physics Data Demand More Powerful Processing", , , BNL-Brookhaven National Lab, Electron-Ion Collider, , , Software & Computing Round Table   

    From Brookhaven National Lab and Thomas Jefferson National Accelerator Facility: “Nuclear Physics Data Demand More Powerful Processing” 

    From Brookhaven National Lab

    and


    Thomas Jefferson National Accelerator Facility

    August 28, 2020
    Kandice Carter
    Jefferson Lab Communications Office
    kcarter@jlab.org

    Jefferson Lab and Brookhaven National Lab partner on a Software & Computing Round Table to track the leading edge of computing and foster collaboration.

    1

    Fans of the popular TV show The Big Bang Theory can picture the sitcom’s physicists standing at a whiteboard, staring hard at equations.

    It’s an iconic image. But is that the future — or even the present — of how nuclear physicists do their jobs? Not really. Not when new experiments demand ever-more powerful data processing and thus ever-more-powerful software and computing.

    “Scientists being at a blackboard and writing up some equations — that is not always the reality,” said Markus Diefenthaler, an experimental nuclear physicist at the U.S. Department of Energy’s Thomas Jefferson National Accelerator Facility in Newport News, Virginia.

    “We also write analysis programs and simulations to make sense of the vast amount of data that we have collected to try to learn about particle structure and dynamics,” Diefenthaler said. “The software and computing can really be an integral and a fundamental part of the science.”

    So integral and so fundamental that in 2016, Diefenthaler helped organize the Software & Computing Round Table, a monthly forum for presentations and discussions among colleagues and Ph.D. students. Its stated goal: to explore the expanding role of software and computing in high energy and nuclear physics and related fields and to foster common projects within the scientific community.

    The group has grown so successful that last year, organizers teamed up with the U.S. Department of Energy’s Brookhaven National Laboratory on Long Island, New York, to broaden their perspective, their offerings and their target audience.

    The collaboration is particularly timely, as the DOE has chosen Brookhaven as the site for its proposed Electron-Ion Collider (EIC), a one-of-a-kind, next-generation facility considered critical to the future of physics research and particle accelerator technology in this country and around the world.

    Electron-Ion Collider (EIC) at BNL, inside the tunnel that currently houses the RHIC.

    Jefferson Lab is a major partner in realizing the EIC, providing key support for this next new collider.

    Torre Wenaus, senior physicist at Brookhaven and leader of its Nuclear and Particle Physics Software group, said the EIC offers a blank canvas and unique opportunity to benefit from science community members with long experience working on multiple generations of software frameworks.

    Their expertise is invaluable for devising frameworks for so-called greenfield experiments — those in emerging areas that are still wide open for innovation, Wenaus said.

    “The EIC is an opportunity to really take an expansive view in deciding how best to do things in a long-range project, without being bound by a lot of existing history and computing infrastructure, while still leveraging the experience that people bring to it from prior activities,” Wenaus said.

    While the EIC project offers tantalizing possibilities for the round table, just as valuable are what the forum offers right now as Jefferson Lab and Brookhaven engage in world-class nuclear physics research that delivers ever-greater amounts of data, which demands ever-greater processing power.

    “Higher luminosity means more data,” said Wenaus, “which means a bigger job processing the data at various stages, from initial decisions as to what data you save, to simulating the physics in our detector.”

    For instance, Jefferson Lab’s upgraded 12 GeV Continuous Electron Beam Accelerator Facility, a DOE Office of Science User Facility, has the highest luminosity in the world, enabling experiments that probe deep into protons and neutrons to study quarks and gluons — the building blocks of the universe — like a mighty microscope. In one key experiment, called GlueX, researchers hope the CEBAF’s enhanced luminosity can produce new particles called hybrid mesons and answer the fundamental question of why no quark has ever been found alone. CEBAF’s high luminosity generates extreme amounts of data in experiments, with GlueX alone generating 1 GB per second.

    And Brookhaven’s Relativistic Heavy Ion Collider (RHIC), also a DOE Office of Science User Facility, is the first in the world capable of smashing together heavy ions. Nuclear physicists use RHIC and its specialized detectors to study a state of matter called quark-gluon plasma. Continual upgrades at RHIC over its 20 years of operations have resulted in a 44-fold increase in luminosity, far beyond what was imagined when the facility was initially designed.

    “These high-luminosity facilities with very complex detectors and data rates demand a lot of computing and really force us to track the leading edge of software and computing,” Wenaus said.

    Sometimes, though, it’s physics that takes the lead. One example of computing and software advances flowing from physics has been the revolution in machine learning and artificial intelligence over the last eight years, he said. A key paper describing such deep learning approaches was published in 2012 just months after the discovery of the elusive Higgs boson elementary particle following a decades-long search. Such data analysis methods, however, have long been explored by physicists in efforts to better understand their data.

    “It’s always interesting to me that everything we’ve done since the Higgs has tracked exactly the same time scale as the really exponential revolution in machine learning that we’ve done over that time,” Wenaus said.

    And for every high-energy physicist with a long-enough memory, he said, another favorite example of physics software and computing technology flowing to the wider world is the World Wide Web, developed at CERN in 1989 to enable scientists, universities and research facilities to share information.

    There’s also been tremendous growth over the last 10 years in what’s known as common software in the science community. Such software has been around for decades, but has become increasingly available as one of many open-source options.

    Common software will be a key topic of a virtual workshop that round table organizers are offering Sept. 29-Oct. 1. The Future Trends in Nuclear Physics Computing workshop is in lieu of a monthly round table and intended to chart a path for software and computing in nuclear physics for the next 10 years.

    Organizers say the Software & Computing Round Table has helped inspire collaboration among physicists and move projects forward.

    “Some of them, such as greenfield frameworks, are still taking shape, and the impact lies primarily in the future,” Wenaus said.

    Computing is integral to modern science, Diefenthaler said, but its value extends beyond mere numbers.

    “A quote which I really like is from one of the pioneers of computing, Richard Hamming,” said Diefenthaler. “He said, ‘The purpose of computing is insight, not numbers.’ And this is really what software and computing is giving us — it’s giving us insight into the scientific questions which we are trying to answer.”

    German-born Diefenthaler joined Jefferson Lab in 2015 and is part of its EIC Center. He is investigating the inner structure of the nucleon, in particular the so-called TMD observables. Transverse momentum dependent observables are being explored to help map out the spin and momentum of the quarks and gluons inside protons and neutrons. Diefenthaler is part of the research collaboration that observed for the first time the Sivers effect, which relates TMD observables to the proton’s spin and the behavior of its quarks and gluons, in measurements of the semi-inclusive deep-inelastic scattering process and provided seminal results for many other TMD observables.

    Wenaus has worked on nuclear physics at Brookhaven since 1997, but he has had many stints at CERN working on the Large Hadron Collider. He is a member of the ATLAS collaboration, which is one of four major experiments at the LHC and, along with the CMS collaboration, first observed the Higgs boson in 2012. Wenaus is also co-leading U.S. ATLAS efforts to help develop software for the High Luminosity Large Hadron Collider (HL-LHC) at CERN. The HL-LHC is an upgrade to the LHC that will significantly boost its acceleration. It’s expected to start taking data around 2027 at a rate that’s an order of magnitude greater than currently possible.

    The round table was inspired by a popular workshop series called Future Trends in Nuclear Physics Computing. The first workshop was organized by Diefenthaler, along with Amber Boehnlein, now head of Jefferson Lab’s new Computational Sciences & Technology Division, and Graham Heyes, head of the lab’s Scientific Computing Department. The second workshop was organized by a group of 10 from six different institutions, and the third workshop, mentioned above, is being organized by the Software & Computing Round Table organizers.

    Topics are chosen by an eight-member committee composed of physicists from Jefferson Lab and Brookhaven. Speakers come from fellow DOE national labs, international accelerator facilities and research universities.

    “We really focus on programming, on how to process data, how to handle data, how to do the analysis,” Diefenthaler said.

    Both physicists stress that anyone interested in learning more and/or contributing to the conversation about the interplay among the topics of nuclear and high energy physics, software and computing are invited to attend Software and Computing Round Table presentations and discussions.

    See the full article here .


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    Jefferson Lab is supported by the Office of Science of the U.S. Department of Energy. DOE’s 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 science.energy.gov.
    Jefferson Science Associates, LLC, a joint venture of the Southeastern Universities Research Association, Inc. and PAE Applied Technologies, manages and operates the Thomas Jefferson National Accelerator Facility, or Jefferson Lab, for the U.S. Department of Energy’s Office of Science.

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    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

     
  • richardmitnick 9:26 am on August 28, 2020 Permalink | Reply
    Tags: BNL-Brookhaven National Lab, Electron-Ion Collider (EIC) at BNL, Exploring the binding force carried by gluons – the strongest force in Nature – will also help physicists unlock the secrets of confinement., , , The Electron-Ion Collider will be a 3D ‘microscope’ for studying the quarks and gluons that are the building blocks of protons; neutrons; and nuclei – in other words all visible matter., The Electron-Ion Collider will extend our knowledge and technological capabilities in completely new ways with wide-ranging impacts in nuclear physics and beyond., This journey will pick up on the exploration of the proton; nuclei; and nuclear matter that has been underway for more than two decades at our two institutions.   

    From Brookhaven National Lab and Thomas Jefferson National Accelerator Facility: “The Electron-Ion Collider – A New Frontier in Nuclear Physics” 

    From Brookhaven National Lab

    and


    JLab-Thomas Jefferson National Accelerator Facility

    August 25, 2020
    Doon Gibbs, BNL
    +1 (631) 344 4608
    gibbs@bnl.gov

    Stuart Henderson, JLab
    +1 757 269 7100
    stuart@jlab.org

    Electron-Ion Collider (EIC) at BNL, inside the tunnel that currently houses the RHIC.

    Science has always been about understanding the world around and within us. At the US Department of Energy’s national laboratories, we take that search for knowledge and the application of what we learn in many directions—from examining the electronic structure of materials for designing better batteries, to searching for drugs that might thwart the deadly coronavirus; from producing new isotopes for treating cancer, to modelling the evolution of the cosmos. Within the next decade, we will be embarking on an exciting new journey into an unexplored frontier in nuclear physics—deep into the particles that make up the nuclei of atoms.

    Scientists at our two institutions — Brookhaven National Laboratory and Thomas Jefferson National Accelerator Facility (JLab)—together with researchers at other national labs and universities throughout the US, will join forces with partners from around the world to build the world’s first polarised Electron-Ion Collider. Supported by ~US$1.6-2.6 billion in funding from the US Department of Energy’s Office of Science and $100m from New York State, this new world-class research facility will collide high energy electrons with protons and the nuclei of heavier atoms such as gold to produce precision 3D snapshots of quarks and gluons – the building blocks of all visible matter – and unlock the secrets of the strongest force in Nature.

    This journey will pick up on the exploration of the proton, nuclei, and nuclear matter that has been underway for more than two decades at our two institutions. Since 2000, scientists have used Brookhaven’s Relativistic Heavy Ion Collider (RHIC) to explore the characteristics of nuclear matter, discovering unexpected details about what matter was like in the very early Universe. We will even reuse some of that facility’s still ground-breaking accelerator components and draw on the expertise gained while vastly expanding its capabilities over the past 20 years. Likewise, since 1995, scientists have used Jefferson Lab’s Continuous Electron Beam Accelerator Facility (CEBAF) to discover new details of the quark structure of protons, neutrons, and nuclei.

    Building on these discoveries, the Electron-Ion Collider will extend our knowledge and technological capabilities in completely new ways, with wide-ranging impacts in nuclear physics and beyond.

    2
    Electron-Ion Collision – as electrons collide with ions at the Electron-Ion Collider (EIC), they will scatter off the quarks within the proton or nucleus. Particles ejected from the collision by these scattering interactions strike various components of a detector. Scientists study the patterns and characteristics of the particles produced to tease out the internal structure of the protons and ions, including the distribution of the quarks and gluons.

    The microcosm within protons

    The Electron-Ion Collider will be a 3D ‘microscope’ for studying the quarks and gluons that are the building blocks of protons, neutrons, and nuclei – in other words, all visible matter. Gluons are the subatomic particles that bind quarks into the more familiar particles that make up matter in today’s world. Without gluons, space itself would be unstable, and atoms – and everything made from them, including stars, planets, and people – would not exist.

    Nuclear physicists estimate that gluons (which themselves are massless) and the force they mediate among quarks may account for nearly 99% of the mass of the protons and neutrons that make up atomic nuclei – the most massive component of all visible matter in the Universe. Yet, we know less about gluons than the Higgs particle, which accounts only for the masses of quarks and electrons. An Electron-Ion Collider promises unforeseen insight into gluons’ mass-building mechanism.

    Collisions at the Electron-Ion Collider will reveal how quarks and gluons are arranged within the larger building blocks of matter, the protons, neutrons, and nuclei. Experiments will search for signs of a new state of matter that theorists predict will emerge as gluons multiply and reach a state of saturation at high energies. Additional experiments will explore whether the presence of multiple protons affects the distribution of gluons within these particles, as it does the distribution of quarks.

    Exploring the binding force carried by gluons – the strongest force in Nature – will also help physicists unlock the secrets of confinement, the property that keeps quarks locked within composite particles. This research will offer insight into gluons’ behaviour not just in ordinary matter, but also in extreme astrophysical environments such as the hearts of merging neutron stars and supernovae.

    In addition, the ability to control the polarisation of colliding electrons and protons in the Electron-Ion Collider will give physicists the tool they need to finally solve a long-standing physics mystery: the origin of proton spin. Though proton spin, an intrinsic angular momentum that is somewhat analogous to the spin of a toy spinning top, is used in nuclear magnetic resonance imaging (NMR and MRI), scientists still don’t know how this property arises from the proton’s inner building blocks. Precision measurements at the Electron-Ion Collider will reveal contributions made by quarks, gluons, and a sea of quark-antiquark pairs to place the final pieces in the proton spin puzzle together.

    3
    The Spin Puzzle – the Electron-Ion Collider (EIC) will be the world’s first polarised electron-proton collider – meaning the ‘spins’ of both colliding particles can be aligned in a controlled way. This will make it possible to experimentally solve the outstanding mystery of how the teeming quarks and gluons inside the proton combine their spins to generate the overall spin carried by the proton.

    Transformative technologies

    How will we use the knowledge gained at the Electron-Ion Collider? As is the case when entering any new frontier, it is difficult to predict. But it might be helpful to think about how experiments of the last century have impacted us today.

    These include fundamental physics experiments conducted 50-100 years ago that revealed the structure of the atom – a positively charged nucleus surrounded by negatively charged orbiting electrons. Those experiments laid the foundation for the theory of quantum mechanics and the design of a wide variety of materials and technologies that drive our economy today – batteries, smart materials, and all our electronics.

    By allowing us to peer inside the nucleus and individual protons, the Electron-Ion Collider will broaden our understanding of the microcosm of quarks and gluons within. We already know that the nuclear strong force through which those fundamental particles interact is considerably more powerful than the electromagnetic interactions described by the theory of quantum mechanics. Unlocking the secrets of the nuclear strong force and solidifying our understanding of its descriptive theory – quantum chromodynamics – may open doors to powering the discoveries and technologies of tomorrow.

    And along the way we will be working with experts from around the world to develop many advanced technologies that will make this exploration possible – and that will undoubtedly advance other areas of science and help to address pressing societal needs.

    As one example, we have been working with partners at Cornell University and the New York State Energy Research and Development Authority on innovative particle acceleration schemes that recycle both the particles and their energy. This energy-saving technology has great potential for use in a system that will keep the Electron-Ion Collider’s beams of colliding ions cool and tightly packed. Keeping ion beams cool will maximise collision rates, or luminosity, and will generate more data for physicists to explore. And the energy-saving acceleration approach could go on to be applied at other future accelerators used in science or for industrial and medical applications, including cancer treatment.

    We are also working with a worldwide community of Electron-Ion Collider scientists – already more than 1,000 physicists from over 200 laboratories and universities throughout the nation and around the world – to gather input on the scientific opportunities at an Electron-Ion Collider, as well as the detector and accelerator capabilities needed to ensure that the Electron-Ion Collider will make the most impactful measurements and get the most out of every particle interaction.

    4
    EIC Collision – as electrons collide with ions at the Electron-Ion Collider (EIC), virtual photons – particles of light that mediate the interaction, denoted by the wavy purple line – will penetrate the proton or nucleus to tease out the structure of the quarks and gluons within.

    Important impacts in physics and beyond

    The technologies being developed for the Electron-Ion Collider will push the evolution of accelerator and detector components, as well as architectures and approaches for handling Big Data, in ways that will have broad benefits for science and society.

    For example, advanced accelerator designs could improve the delivery of particle beams with cell-killing energy directly to tumours, with lower cost and better outcomes than today’s radiotherapies. These accelerator technologies could also find their way into machines used by scientists and industry to make and test computer chips; explore and develop new materials for batteries, solar cells, and other energy applications; and to study bacterial and viral proteins and design drugs and vaccines to protect human health. Detectors developed for tracking particles at the Electron-Ion Collider may lead to better ways to identify illicit cargo and support other national security applications.

    Advances in any of these areas – from drug development to materials design to understanding global challenges such as pandemics and climate change – rely increasingly on computational resources that allow scientists to sort through unprecedented volumes of data. The computational resources and techniques developed to extract elusive signals from billions of Electron-Ion Collider particle interactions will inevitably drive the evolution of more powerful tools for tackling these other data-intensive challenges.

    Running the Electron-Ion Collider will also facilitate continued operations of two Brookhaven Lab facilities that employ the same accelerator infrastructure: one that develops and produces crucial isotopes used by doctors to diagnose and treat cancer; and one that simulates the effects of space radiation, which was designed to help protect future astronauts and also advances scientists’ understanding of cancer mechanisms, treatments, and potential protective measures.

    And, of course, the prospect of entering a new frontier will attract the best and brightest minds from around the world. The Electron-Ion Collider will offer countless opportunities for training a highly skilled workforce – the scientists, engineers, and tech-savvy workers who will drive tomorrow’s technological and economic advances and maintain our leadership in these essential areas for decades to come.

    We are looking forward to this journey and to sharing the discoveries and other benefits with our nation and the world.

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    JLab campus

    Jefferson Lab is supported by the Office of Science of the U.S. Department of Energy. DOE’s 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 science.energy.gov.
    Jefferson Science Associates, LLC, a joint venture of the Southeastern Universities Research Association, Inc. and PAE Applied Technologies, manages and operates the Thomas Jefferson National Accelerator Facility, or Jefferson Lab, for the U.S. Department of Energy’s Office of Science.

    BNL Campus

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    BNL Center for Functional Nanomaterials

    BNL NSLS-II


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    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

     
  • richardmitnick 6:05 am on August 27, 2020 Permalink | Reply
    Tags: "Brookhaven Lab to Lead Quantum Research Center", BNL-Brookhaven National Lab, C^2QA-Co-design Center for Quantum Advantage, , Quantum computers have the potential to solve scientific and other kinds of problems that would be practically impossible for traditional supercomputers.   

    From Brookhaven National Lab: “Brookhaven Lab to Lead Quantum Research Center” 

    From Brookhaven National Lab

    August 26, 2020
    Ariana Manglaviti
    amanglaviti@bnl.gov

    This multidisciplinary center is one of five awarded by the U.S. Department of Energy to conduct basic research in quantum information science.

    1
    Led by Brookhaven Lab, the Co-design Center for Quantum Advantage seeks to reach quantum advantage—the point where a quantum computer outperforms a classical one on a useful task—in scientific computations by simultaneously designing hardware and software. BNL.

    The U.S. Department of Energy (DOE) Office of Science has selected Brookhaven National Laboratory to lead one of five National Quantum Information Science (QIS) Research Centers. Supporting the National Quantum Initiative Act, these interdisciplinary, multi-institutional centers will facilitate the advancement of QIS technology. Realizing the full potential of quantum-based applications in computing, communication, and sensing will benefit national security, economic competitiveness, and leadership in scientific discovery.

    Brookhaven Lab will lead the Co-design Center for Quantum Advantage (C^2QA), which will focus on quantum computing. Comprising several national labs, research centers, universities, and industry, the C^2QA team will build the fundamental tools necessary for the United States to create quantum computers that provide a true advantage over their classical counterparts.

    World-leading experts in QIS, materials science, computer science, and theory will work together to resolve performance issues with today’s quantum computers by simultaneously designing software and hardware (co-design). Their goal is to achieve quantum advantage in computations for high-energy and nuclear physics, chemistry, materials science, condensed matter physics, and other fields. Quantum advantage refers to a quantum computer outperforming a classical computer on a useful task.

    “A key feature of our effort is a singular focus on co-design: a tight partnership between materials discovery, device development, system integration, and algorithms synthesis—all driven by benchmarks and applications to real science problems and enabled by a team experienced at crossing disciplinary boundaries,” said C^2QA principal investigator Isaac Chuang, professor of electrical engineering and computer science and professor of physics at MIT.

    “Today’s announcement underscores the United States’ leadership in creating a quantum industry,” said Dario Gil, director of IBM Research, one of the C^2QA partners. “The National Quantum Initiative brings together the best of the private and public sectors, combining skills, expertise, and research to accelerate our ambitious mission to reach quantum advantage.”

    Quantum computers have the potential to solve scientific and other kinds of problems that would be practically impossible for traditional supercomputers. However, the current generation—called noisy intermediate-scale quantum—suffers from a high error rate because of noise, faults, and loss of quantum coherence. Quantum bits (qubits), the information-storing elements of quantum computers, are very delicate. Vibrations, temperature changes, electromagnetic waves, and other interactions between qubits and the environment or material defects in qubits can cause quantum decoherence. In quantum decoherence, these errors cause the qubits to lose their information, and the calculation cannot be completed.

    “The biggest challenge in the field today is to make quantum computers truly robust and scalable,” said C^2QA principal investigator Robert Schoelkopf, Yale Sterling Professor of Applied Physics and director of the Yale Quantum Institute. “By combining materials science, improved devices, and algorithmic innovations, C^2QA will develop the science to solve this problem and ensure that the United States leads the way into the era of useful quantum computing.”

    Through materials, devices, and software co-design efforts, the team will understand and control material properties to extend coherence time, design devices to generate more robust qubits, optimize algorithms to target specific scientific applications, and develop error-correction solutions. To achieve these goals, they will leverage materials characterization facilities at Brookhaven’s Center for Functional Nanomaterials (CFN) [below] and National Synchrotron Light Source II (NSLS-II) [below], device design and fabrication capabilities in industry and academia, and IBM’s Qiskit open-source framework for writing quantum programs and its Q Prime prototype quantum computer.

    IBM iconic image of Quantum computer

    “Because of the highly interdisciplinary nature of building a practical quantum computer, no individual scientist can have all the necessary expertise,” said C^2QA Deputy Director Andrew Houck, professor of electrical engineering at Princeton and director of the Princeton Quantum Initiative. “C^2QA will unite scientists from all areas of quantum computing to focus on this singular challenge. Bringing together academic and industry experts and the world-class facilities at Brookhaven’s NSLS-II and CFN will enable us to understand the fundamental limits that materials impose on quantum computers.”

    “Achieving these objectives will set the foundation for a new generation of quantum computers,” said C^2QA Director Steven Girvin, the Eugene Higgins Professor of Physics at Yale University and a dual appointee in Brookhaven’s Energy and Photon Sciences Directorate. “Technologies emerging from C^2QA that are scaled up by industrial partners will provide a quantum computing platform with error correction able to address classically intractable calculations essential to DOE mission science.”

    James Misewich, the associate laboratory director for Energy and Photon Sciences at Brookhaven, will oversee C^2QA. In addition to his leadership role as deputy director, Houck will ensure the three thrusts (materials, devices, and software) are integrated and oversee an outreach and workforce development program for the center to provide students with QIS educational opportunities. Michael Bebon, a senior advisor at NSLS-II, will manage operations.

    Total planned funding for the center is $115 million over five years, with $15 million in Fiscal 2020 dollars and outyear funding contingent on congressional appropriations.

    The CFN and NSLS-II are both DOE Office of Science User Facilities. The partnering institutions on C^2QA are Ames Laboratory, Caltech, City College of New York, Columbia University, Harvard University, Howard University, IBM, Johns Hopkins University, MIT, Montana State University, National Aeronautics and Space Administration’s Ames Research Center, Northwestern University, Pacific Northwest National Laboratory, Princeton University, State University of New York Polytechnic Institute, Stony Brook University, Thomas Jefferson National Accelerator Facility, University of California-Santa Barbara, University of Massachusetts-Amherst, University of Pittsburgh, University of Washington, Virginia Tech, and Yale University.

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    BNL Campus

    Brookhaven campus

    BNL Center for Functional Nanomaterials

    BNL NSLS-II


    BNL NSLS II

    BNL RHIC Campus

    BNL/RHIC Star Detector

    BNL Phenix Detector

    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

     
  • richardmitnick 2:13 pm on July 25, 2020 Permalink | Reply
    Tags: "The Qubit Connection", A configuration covering a total of approximately 140 km (roughly 87 miles) using commercially available telecommunications fiber connecting the SBU and Brookhaven Lab campuses., A three-node quantum network prototype extending the reach and potential of future quantum communication systems., BNL-Brookhaven National Lab, Brookhaven Lab–Stony Brook University partnership extends the potential of quantum communications., Stoney Brook University-SUNY, The longest successful quantum communication link experiment in the United States., The true security and capability of a quantum Internet will only be realized with working quantum repeaters., This experiment clearly demonstrates the cutting-edge quantum Internet technology research happening at Stony Brook and BNL and the significance of our findings.   

    From Brookhaven National Lab and Stoney Brook University: “The Qubit Connection” 

    From Brookhaven National Lab

    and


    Stoney Brook University-SUNY

    July 23, 2020

    Contact: Peter Genzer
    genzer@bnl.gov
    (631) 344-3174

    Written by Charity Plata

    Brookhaven Lab–Stony Brook University partnership extends the potential of quantum communications.

    1
    The burgeoning Brookhaven-SBU quantum communications infrastructure started with an experiment in 2019 that used existing fiber on the Brookhaven Lab campus to perform transmission of entanglement over approximately 18 km (11 miles). Now, the Brookhaven-SBU team has logged its latest success: a single-photon-level qubit communication in a twin-field configuration covering 140 km, representing the longest quantum communication link experiment in the United States. Image courtesy of Stony Brook University.

    As part of a federally funded quantum network development program, scientists from the U.S. Department of Energy’s Brookhaven National Laboratory and Stony Brook University (SBU) have demonstrated a three-node quantum network prototype, extending the reach and potential of future quantum communication systems. For the first time, they achieved transmission of single-photon level polarization quantum bits (“qubits”) in a configuration covering a total of approximately 140 km (roughly 87 miles), using commercially available telecommunications fiber connecting the SBU and Brookhaven Lab campuses.

    Currently, this marks the longest successful quantum communication link experiment in the United States and represents another noteworthy advancement by the Brookhaven Lab–SBU team. In only two years, the team’s efforts to develop a working long-distance quantum network—the foundation for the nation’s future quantum Internet infrastructure—have led to important “firsts” in U.S.-based quantum research. With this recent success covering 140 km, the team has substantially closed the gap between operational quantum communications infrastructure in the United States versus international work, especially that done in China, which has a strong research focus in this area.

    “The Department of Energy is proud to host the longest form of quantum communication at Brookhaven National Lab and Stony Brook University,” said DOE Under Secretary for Science Paul Dabbar. “We must continue to build upon this advanced technology to further our nation’s efforts towards achieving a long-distance quantum network.”

    3
    The “Charlie” photon detector setup at Brookhaven Lab.

    “This experiment clearly demonstrates the cutting-edge quantum Internet technology research happening at Stony Brook and BNL and the significance of our findings,” said Maurie McInnis, President of Stony Brook University. “The long and deep history of collaborations between our two institutions continues to yield some of modern society’s most exciting scientific discoveries, propelling us all forward.”

    Brookhaven National Laboratory Director Doon Gibbs added: “This is a tremendous forward stride that demonstrates our commitment to supporting the nation’s efforts in quantum research, especially toward facilitating a nationwide quantum Internet. We are proud of the innovative work that this team, with talented scientists and engineers from both Stony Brook and Brookhaven, continues to deliver.”

    An Ideal Infrastructure

    4
    The “Alice” qubit generator setup at SBU. Photo courtesy of Stony Brook University.

    The latest experiment expands earlier work that established local entanglement-sharing quantum networks on the Brookhaven and SBU campuses. These two local networks were joined using two fiber quantum channels that connect “sister” quantum laboratories on both campuses. In two locations at SBU (dubbed “Alice” and “Bob”), the team is able to generate telecom-tuned single-photon-level polarization qubits. The two qubits streams then are transported in independent fibers (from Crown Castle Fiber, a provider of shared communications infrastructure) to a third station (“Charlie”) at Brookhaven, where they are detected using telecom nanowire single-photon counters. This infrastructure, called a twin-field quantum network, offers a promising approach toward achieving secure quantum communications over long distances.

    According to Eden Figueroa, a joint appointee with Brookhaven’s Instrumentation Division and Computational Science Initiative and Quantum Information Technology group lead at SBU who oversees the quantum networking testbed project, an important aspect of the experiment is that the qubits are fully quantum memory compatible, produced at frequencies tuned to rubidium resonances in the telecom spectrum. This will allow for the deployment of quantum memory buffers, atom-filled glass cells that store quantum information and are manipulated using lasers to control their atomic states, in either side of the network to achieve secure quantum communication over long distances. These exchanges are already possible because the team has designed the infrastructure to be quantum repeater friendly from the beginning and at every aspect.

    “We have already built several portable room-temperature quantum memory buffers,” Figueroa said. “Now, we have taken the next beautiful step: creating the long-distance quantum communication infrastructure to connect them.”

    Ready to Test Quantum Memory-based Repeaters

    Presently, a viable quantum repeater is the single most valuable component missing from the mix of innovations needed to realize a working quantum Internet. A quantum repeater would function much like a “signal booster” does for a cellular network by amplifying digital transmissions over long distances. However, in an ideal quantum realm, the repeater would not lead to decoherence, or disruption of the qubits’ quantum entanglement state. This would assure the integrity of the information, affording an unprecedented level of communications security.

    “The true security and capability of a quantum Internet will only be realized with working quantum repeaters,” Figueroa explained. “Our results have set the stage for an infrastructure to build a viable quantum repeater. We have all the right properties in the photons. Our nodes, fibers, and lasers have been tested and are compatible with quantum memories. Then, the quantum memories themselves are deployable. We now have all the compatible infrastructure. I am very excited about what’s coming next.”

    More than a Quantum Connection

    The Crown Castle telecom fiber that connects the Brookhaven and SBU labs provided the foundation for the recent 140 km (~87 miles) long-distance quantum communication over classical fiber systems, which has long posed a major challenge to the worldwide quantum networking community. Notably, Figueroa said the actual experimental setup with all its necessary equipment and infrastructure had only been complete and in place for roughly 10 days before the team took the initial leap to transmit the qubits from SBU to a superconducting single-photon detector at Brookhaven Lab.

    5
    The measured histograms show the reconstructed (in quasi-real time) Gaussian temporal-wave function of the qubits generated at SBU and measured at Brookhaven Lab. They illustrate the successful single-photon-level qubit communication in a twin-field configuration.

    “To our knowledge, this is the longest quantum communication link experiment in the United States, and it really shows the effectiveness of our collaborative research approach that has kept the notion of being repeater-compatible since the beginning,” he added.

    Most importantly to Figueroa, the team’s work shows the value in creating connections between academia and national laboratories. In this case, it represents something quite literal: SBU and Brookhaven are physically connected, yet they share even more by way of the multiple staff who are contributing their expertise along the way.

    “We’re working together. The synergistic collaboration between academia and the national labs is already there, and only together can we perform such challenging experiments,” he added.

    This collaborative research has been funded by the U.S. Department of Energy’s QIS initiative in the Office of Advanced Scientific Computing Research (ASCR)’s recently launched quantum optical networks program.

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    BNL Campus

    Brookhaven campus

    BNL Center for Functional Nanomaterials

    BNL NSLS-II


    BNL NSLS II

    BNL RHIC Campus

    BNL/RHIC Star Detector

    BNL Phenix Detector

    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

     
  • richardmitnick 11:11 am on July 15, 2020 Permalink | Reply
    Tags: "Charm Quarks Offer Clues to Confinement", , BNL-Brookhaven National Lab, BNL/RHIC Star Heavy Ion Tracker, Hadrons made of two or three quarks are the building blocks of visible matter in our world—including the protons and neutrons that make up the nuclei of atoms., , Nuclear physicists are trying to understand how particles called quarks and gluons combine to form hadrons., , , , , RHIC’s heavy ion collisions create a state of matter known as quark-gluon plasma (QGP)., Tracking particles containing charm quarks offers insight into how quarks combine., We can explore the mechanism of hadronization and how the strong nuclear force keeps quarks confined in ordinary matter.   

    From Brookhaven National Lab: “Charm Quarks Offer Clues to Confinement” 

    From Brookhaven National Lab

    July 15, 2020
    Karen McNulty Walsh
    kmcnulty@bnl.gov

    Tracking particles containing charm quarks offers insight into how quarks combine.

    1
    A gold–gold collision recorded by the Heavy Flavor Tracker (HFT) component of the STAR detector [below] at the Relativistic Heavy Ion Collider (RHIC) [below]. The white points show “hits” recorded by particles emerging from the collision as they strike sensors in three layers of the HFT. Scientists use the hits to reconstruct charged particle tracks (red and green lines) to measure the relative abundance of certain kinds of particles emerging from the collision—in this case, charmed lambda particles. (Image courtesy of STAR Collaboration)

    BNL RHIC STAR Heavy Flavor Tracker

    Nuclear physicists are trying to understand how particles called quarks and gluons combine to form hadrons, composite particles made of two or three quarks. To study this process, called hadronization, a team of nuclear physicists used the STAR detector at the Relativistic Heavy Ion Collider—a U.S. Department of Energy Office of Science user facility for nuclear physics research at DOE’s Brookhaven National Laboratory—to measure the relative abundance of certain two- and three-quark hadrons created in energetic collisions of gold nuclei. The collisions momentarily “melt” the boundaries between the individual protons and neutrons that make up the gold nuclei so scientists can study how their inner building blocks, the quarks and gluons, recombine.

    The STAR physicists studied particles containing heavy “charm” quarks, which are easier to track than lighter particles, to see how the measurements matched up with predictions from different explanations of hadronization. The measurements, published in Physical Review Letters, revealed many more three-quark hadrons than would have been expected by a widely accepted explanation of hadronization known as fragmentation. The results suggest that, instead, quarks in the dense particle soup created at RHIC recombine more directly through a mechanism known as coalescence.

    “Hadrons made of two or three quarks are the building blocks of visible matter in our world—including the protons and neutrons that make up the nuclei of atoms. But we never see their inner building blocks—the quarks and gluons—as free objects because quarks are always ‘confined’ within composite particles,” said Xin Dong, a physicist at DOE’s Lawrence Berkeley National Laboratory (LBNL) and a leader of this analysis for the STAR Collaboration.

    RHIC’s heavy ion collisions create a state of matter known as quark-gluon plasma (QGP), a hot particle soup that mimics what the early universe was like, in which quarks are “deconfined,” or set free, from their ordinary bounds within composite particles called hadrons.

    “By tracking the particles that stream out of RHIC’s collisions we can explore the mechanism of hadronization and how the strong nuclear force keeps quarks confined in ordinary matter,” said Helen Caines, a professor at Yale University and co-spokesperson of the STAR Collaboration.

    The STAR physicists measured charmed hadrons (hadrons containing heavy “charm” quarks) using the high-resolution Heavy Flavor Tracker (HFT) installed at the center of the 4-meter-wide Time Projection Chamber of RHIC’s STAR detector.

    “The HFT ‘zooms in’ on particles such as the three-quark charmed lambda, which decays less than 0.1 millimeter from the center of the collision,” said Brookhaven Lab physicist Flemming Videbaek, the STAR HFT project manager.

    Combining “hits” in the HFT with measurements of the decay products farther out in the STAR detector, physicists can count up how many three-quark charmed lambdas vs. two-quark charmed “D-zero” (D0) particles emerge from the QGP.

    “We used a supervised machine learning technique to suppress the large background for the detection of charmed lambda particles,” said Sooraj Radhakrishnann, a postdoctoral fellow from Kent State University and Berkeley Lab who conducted the main analysis.

    The results from STAR counted charmed lambdas and D0 particles in nearly equal numbers. That was far more charmed lambdas than had been predicted by a well-accepted mechanism of hadronization known as fragmentation.

    “Fragmentation accurately describes many experimental results from high-energy particle physics experiments,” Dong said. The mechanism involves energetic quarks or gluons “exciting” the vacuum and “splitting” to form quark-antiquark pairs. As the splitting process progresses, it creates an abundant pool of quarks and antiquarks that can combine to form two- and three-quark hadrons, he explained.

    But the fragmentation explanation predicts that fewer charmed lambda particles than D0 particles should emerge from heavy ion collisions in the momentum range measured at RHIC. STAR’s observation of “charmed baryon enhancement” (resulting in nearly equal numbers of charmed lambda and D0 particles) supports an alternate mechanism for hadronization. Known as coalescence, this explanation posits that the density of RHIC’s QGP particle soup brings quarks into close enough proximity to allow them to recombine into composite particles directly.

    “The STAR results suggest that coalescence plays an important role in charm quark hadronization in heavy-ion collisions, at least in the momentum range measured in this experiment,” Dong said.

    Understanding the mechanism of coalescence may offer new insights that help reveal how quarks and gluons become confined within hadrons to build up the structure of atomic nuclei—the heart of the matter that makes up everything visible in our world.

    This work was supported in part by the U.S. DOE Office of Science, the U.S. National Science Foundation, the Ministry of Education and Science of the Russian Federation, National Natural Science Foundation of China, Chinese Academy of Science, the Ministry of Science and Technology of China and the Chinese Ministry of Education, the National Research Foundation of Korea, Czech Science Foundation and Ministry of Education, Youth and Sports of the Czech Republic, Hungarian National Research, Development and Innovation Office, New National Excellency Programme of the Hungarian Ministry of Human Capacities, Department of Atomic Energy and Department of Science and Technology of the Government of India, the National Science Centre of Poland, the Ministry of Science, Education and Sports of the Republic of Croatia, RosAtom of Russia and German Bundesministerium fur Bildung, Wissenschaft, Forschung and Technologie (BMBF) and the Helmholtz Association.

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    BNL Campus

    Brookhaven campus

    BNL Center for Functional Nanomaterials

    BNL NSLS-II


    BNL NSLS II

    BNL RHIC Campus

    BNL/RHIC Star Detector

    BNL Phenix Detector

    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

     
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