Tagged: BNL PHENIX Toggle Comment Threads | Keyboard Shortcuts

  • richardmitnick 12:02 pm on December 10, 2018 Permalink | Reply
    Tags: , , BNL PHENIX, , , , , The “perfect” liquid, This soup of quarks and gluons flows like a liquid with extremely low viscosity   

    From Brookhaven National Lab: “Compelling Evidence for Small Drops of Perfect Fluid” 

    From Brookhaven National Lab

    December 10, 2018

    Karen McNulty Walsh
    kmcnulty@bnl.gov
    (631) 344-8350

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

    1
    If collisions between small projectiles—protons (p), deuterons (d), and helium-3 nuclei (3He)—and gold nuclei (Au) create tiny hot spots of quark-gluon plasma, the pattern of particles picked up by the detector should retain some “memory” of each projectile’s initial shape. Measurements from the PHENIX experiment match these predictions with very strong correlations between the initial geometry and the final flow patterns. Credit: Javier Orjuela Koop, University of Colorado, Boulder

    Nuclear physicists analyzing data from the PHENIX detector [see below] at the Relativistic Heavy Ion Collider (RHIC) [see below]—a U.S. Department of Energy (DOE) Office of Science user facility for nuclear physics research at Brookhaven National Laboratory—have published in the journal Nature Physics additional evidence that collisions of miniscule projectiles with gold nuclei create tiny specks of the perfect fluid that filled the early universe.

    Scientists are studying this hot soup made up of quarks and gluons—the building blocks of protons and neutrons—to learn about the fundamental force that holds these particles together in the visible matter that makes up our world today. The ability to create such tiny specks of the primordial soup (known as quark-gluon plasma) was initially unexpected and could offer insight into the essential properties of this remarkable form of matter.

    “This work is the culmination of a series of experiments designed to engineer the shape of the quark-gluon plasma droplets,” said PHENIX collaborator Jamie Nagle of the University of Colorado, Boulder, who helped devise the experimental plan as well as the theoretical simulations the team would use to test their results.

    The PHENIX collaboration’s latest paper includes a comprehensive analysis of collisions between small projectiles (single protons, two-particle deuterons, and three-particle helium-3 nuclei) with large gold nuclei “targets” moving in the opposite direction at nearly the speed of light. The team tracked particles emerging from these collisions, looking for evidence that their flow patterns matched up with the original geometries of the projectiles, as would be expected if the tiny projectiles were indeed creating a perfect liquid quark-gluon plasma.

    “RHIC is the only accelerator in the world where we can perform such a tightly controlled experiment, colliding particles made of one, two, and three components with the same larger nucleus, gold, all at the same energy,” said Nagle.

    Perfect liquid induces flow

    The “perfect” liquid is now a well-established phenomenon in collisions between two gold nuclei at RHIC, where the intense energy of hundreds of colliding protons and neutrons melts the boundaries of these individual particles and allows their constituent quarks and gluons to mingle and interact freely. Measurements at RHIC show that this soup of quarks and gluons flows like a liquid with extremely low viscosity (aka, near-perfection according to the theory of hydrodynamics). The lack of viscosity allows pressure gradients established early in the collision to persist and influence how particles emerging from the collision strike the detector.

    “If such low viscosity conditions and pressure gradients are created in collisions between small projectiles and gold nuclei, the pattern of particles picked up by the detector should retain some ‘memory’ of each projectile’s initial shape—spherical in the case of protons, elliptical for deuterons, and triangular for helium-3 nuclei,” said PHENIX spokesperson Yasuyuki Akiba, a physicist with the RIKEN laboratory in Japan and the RIKEN/Brookhaven Lab Research Center.

    PHENIX analyzed measurements of two different types of particle flow (elliptical and triangular) from all three collision systems and compared them with predictions for what should be expected based on the initial geometry.

    “The latest data—the triangular flow measurements for proton-gold and deuteron-gold collisions newly presented in this paper—complete the picture,” said Julia Velkovska, a deputy spokesperson for PHENIX, who led a team involved in the analysis at Vanderbilt University. “This is a unique combination of observables that allows for decisive model discrimination.”

    “In all six cases, the measurements match the predictions based on the initial geometric shape. We are seeing very strong correlations between initial geometry and final flow patterns, and the best way to explain that is that quark-gluon plasma was created in these small collision systems. This is very compelling evidence,” Velkovska said.

    Comparisons with theory

    The geometric flow patterns are naturally described in the theory of hydrodynamics, when a near-perfect liquid is created. The series of experiments where the geometry of the droplets is controlled by the choice of the projectile was designed to test the hydrodynamics hypothesis and to contrast it with other theoretical models that produce particle correlations that are not related to initial geometry. One such theory emphasizes quantum mechanical interactions—particularly among the abundance of gluons postulated to dominate the internal structure of the accelerated nuclei—as playing a major role in the patterns observed in small-scale collision systems.

    The PHENIX team compared their measured results with two theories based on hydrodynamics that accurately describe the quark-gluon plasma observed in RHIC’s gold-gold collisions, as well as those predicted by the quantum-mechanics-based theory. The PHENIX collaboration found that their data fit best with the quark-gluon plasma descriptions—and don’t match up, particularly for two of the six flow patterns, with the predictions based on the quantum-mechanical gluon interactions.

    The paper also includes a comparison between collisions of gold ions with protons and deuterons that were specifically selected to match the number of particles produced in the collisions. According to the theoretical prediction based on gluon interactions, the particle flow patterns should be identical regardless of the initial geometry.

    “With everything else being equal, we still see greater elliptic flow for deuteron-gold than for proton-gold, which matches more closely with the theory for hydrodynamic flow and shows that the measurements do depend on the initial geometry,” Velkovska said. “This doesn’t mean that the gluon interactions do not exist,” she continued. “That theory is based on solid phenomena in physics that should be there. But based on what we are seeing and our statistical analysis of the agreement between the theory and the data, those interactions are not the dominant source of the final flow patterns.”

    PHENIX is analyzing additional data to determine the temperature reached in the small-scale collisions. If hot enough, those measurements would be further supporting evidence for the formation of quark-gluon plasma.

    The interplay with theory, including competitive explanations, will continue to play out. Berndt Mueller, Brookhaven Lab’s Associate Director for Nuclear and Particle Physics, has called on experimental physicists and theorists to gather to discuss the details at a special workshop to be held in early 2019. “This back-and-forth process of comparison between measurements, predictions, and explanations is an essential step on the path to new discoveries—as the RHIC program has demonstrated throughout its successful 18 years of operation,” he said.

    This work was supported by the DOE Office of Science, and by all the agencies and organizations supporting research at PHENIX.

    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

    BNL NSLS-II


    BNL NSLS II

    BNL RHIC Campus

    BNL/RHIC Star Detector

    BNL RHIC PHENIX

    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.
    i1

     
  • richardmitnick 11:27 am on September 22, 2017 Permalink | Reply
    Tags: 2016 deuteron-gold collisions, , BNL PHENIX, , , ,   

    From BNL: “New Evidence for Small, Short-Lived Drops of Early Universe Quark-Gluon Plasma?” 

    Brookhaven Lab

    September 18, 2017
    Karen McNulty Walsh
    kmcnulty@bnl.gov
    (631) 344-8350
    Peter Genzer
    genzer@bnl.gov
    (631) 344-3174

    1
    The PHENIX detector at the Relativistic Heavy Ion Collider (RHIC) with a superimposed image of reconstructed particle tracks picked up by the detector.

    BNL RHIC Campus

    BNL/RHIC Star Detector

    BNL RHIC PHENIX

    Particles emerging from even the lowest energy collisions of small deuterons with large heavy nuclei at the Relativistic Heavy Ion Collider (RHIC)—a U.S. Department of Energy Office of Science User Facility for nuclear physics research at DOE’s Brookhaven National Laboratory—exhibit behavior scientists associate with the formation of a soup of quarks and gluons, the fundamental building blocks of nearly all visible matter. These results from RHIC’s PHENIX experiment suggest that these small-scale collisions might be producing tiny, short-lived specks of matter that mimics what the early universe was like nearly 14 billion years ago, just after the Big Bang.

    Scientists built RHIC, in large part, to create this “quark-gluon plasma” (QGP) so they could study its properties and learn how Nature’s strongest force brings quarks and gluons together to form the protons, neutrons, and atoms that make up the visible universe today. But they initially expected to see signs of QGP only in highly energetic collisions of two heavy ions such as gold. The new findings—correlations in the way particles emerge from the collisions that are consistent with what physicists have observed in the more energetic large-ion collisions—add to a growing body of evidence from RHIC and Europe’s Large Hadron Collider (LHC) that QGP may be created in smaller systems as well.

    The PHENIX collaboration has submitted the findings in two separate papers to the journals Physical Review Letters and Physical Review C, and will present these results at a meeting in Krakow, Poland this week.

    “These are the first papers that come out of the 2016 deuteron-gold collisions, and this is one indication that we are probably creating QGP in small systems,” said Julia Velkovska, a deputy spokesperson for PHENIX from Vanderbilt University. “But there are other things that we have seen in the larger systems that we have yet to investigate in this new data. We’ll be looking for other evidence of QGP in the small systems using different ways to study the properties of the system we are creating,” she said.

    Collective flow

    One of the earliest signs that RHIC’s collisions of two gold ions were creating QGP came in the form of “collective flow” of particles. More particles emerged from the “equator” of two semi-overlapping colliding ions than perpendicular to the collision direction. This elliptical flow pattern, scientists believe, is caused by interactions of the particles with the nearly “perfect”—meaning free-flowing—liquid-like QGP created in the collisions. Since then, collisions of smaller particles with heavy ions have resulted in similar flow patterns at both RHIC and the LHC, albeit on a smaller scale. There has also been evidence that flow patterns have a strong relationship with the geometrical shape of the projectile particle that is colliding with the larger nucleus.

    “With these results in hand, we wanted to try smaller and smaller systems at different energies,” Velkovska said. “If you change the energy, you can change the time that the system stays in the liquid phase, and maybe make it disappear.”

    In other words, they wanted to see if they could turn the creation of QGP off.

    “After so many years we have learned that when QGP is created in the collisions we know how to recognize it, but that doesn’t mean we really understand how it works,” Velkovska said. “We are trying to understand how the perfect-fluid behavior emerges and evolves. What we are doing now—going down in energy, changing the size—is an effort to learn how this behavior arises in different conditions. RHIC is the only collider in the world that allows such a range of studies over different collision energies with different colliding particle species.”

    Turning down the energy

    Over a period of about five weeks in 2016, the PHENIX team explored collisions of deuterons (made of one proton and one neutron) with gold ions at four different energies (200, 62.4, 39, and 19.6 billion electron volts, or GeV).

    “Thanks to the versatility of RHIC and the ability of the staff in Brookhaven’s Collider-Accelerator Department to quickly switch and tune the machine for different collision energies, PHENIX was able to record more than 1.5 billion collisions in this short period of time,” Velkovska said.

    3
    For each collision energy in the beam energy scan, the central panel shows an early-time snapshot of the coordinates of quarks emerging from a deuteron-gold (d-Au) collision as simulated in a transport-model theory calculation. The right panel shows the elliptic flow of the final-state hadrons as measured by PHENIX (closed points), along with the prediction from the theory (solid curve). No image credit.

    For the paper submitted to PRC, Darren McGlinchey, a PHENIX collaborator from Los Alamos National Laboratory, led an analysis of how particles emerged along the elliptical plane of the collisions as a function of their momentum, how central (fully overlapping) the collisions were, and how many particles were produced.

    “Using a deuteron projectile produces a highly elliptical shape, and we observed a persistence of that initial geometry in the particles we detect, even at low energy,” McGlinchey said. Such shape persistence could be caused by interaction with a QGP created in these collisions. “This result is not sufficient evidence to declare that QGP exists, but it is a piece of mounting evidence for it,” he said.

    Ron Belmont, a PHENIX collaborator from the University of Colorado, led an analysis of how the flow patterns of multiple particles (two and four particles at each energy and six at the highest energy) were correlated. Those results were submitted to PRL.

    “We found a very similar pattern in both two- and four-particle correlations for all the different energies, and in six-particle correlations at the highest energy as well,” Belmont said.

    “Both results are consistent that particle flow is observed down to lowest energy. So the two papers work together to paint a nice picture,” he added.

    There are other possible explanations for the findings, including the postulated existence of another form of matter known as color glass condensate that is thought to be dominated by the presence of gluons within the heart of all visible matter.

    “To distinguish color glass condensate from QGP, we need more detailed theoretical descriptions of what these things look like,” Belmont said.

    Velkovska noted that many new students have been recruited to continue the analysis of existing data from the PHENIX experiment, which stopped taking data after the 2016 run to make way for a revamped detector known as sPHENIX.

    “There is a lot more to come from PHENIX,” she said.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition
    BNL Campus

    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.
    i1

     
  • richardmitnick 11:51 am on June 15, 2016 Permalink | Reply
    Tags: , , BNL PHENIX, BNL sPHENIX, , , ,   

    From BNL: “Introducing…sPHENIX!” 

    Brookhaven Lab

    June 15, 2016
    Karen McNulty Walsh

    1
    Members of the new sPHENIX collaboration at a meeting held at Brookhaven Lab in May 2016, with co-spokespersons Dave Morrison (green T-shirt, jeans) and Gunther Roland (blue shirt, black jeans) front and center.

    From the very beginning, there were hints that particle collisions at the Relativistic Heavy Ion Collider (RHIC) were producing something unusual. This U.S. Department of Energy (DOE) Office of Science User Facility at Brookhaven National Laboratory was designed to recreate the incredibly hot and dense conditions of matter in the early universe by colliding atomic nuclei at high enough energies to “melt” their constituent protons and neutrons. The collisions would “free” those particles’ inner building blocks—quarks and gluons—so nuclear physicists could study their behavior unbound from ordinary matter.

    Results from RHIC show that these particle smashups have indeed created a superhot primordial soup called “quark-gluon plasma” (QGP)—but one in which the quarks and gluons, though liberated from their protons and neutrons, continue to interact strongly. These strong interactions make the plasma flow like a nearly “perfect” liquid.

    RHIC’s discovery of the perfect liquid set off a decade-long and very successful effort to characterize its remarkable properties—both at RHIC and at Europe’s Large Hadron Collider (LHC), where physicists conduct complementary studies of quark-gluon plasma for a few weeks of each year. But understanding exactly how the QGP’s perfect fluidity and other collective properties emerge from its point-like constituent particles remains a compelling mystery.

    To address that mystery, a group of nuclear physicists has formed a new scientific collaboration that will expand on discoveries made by RHIC’s existing STAR and PHENIX research groups. This new collaboration, made up of veterans of the field and researchers just beginning their careers, has precise ideas about the measurements its members would like to make—and hopes of upgrading the PHENIX detector to make those measurements at RHIC.

    “What remains to be done is to understand how the QGP’s properties arise or emerge from the underlying quark and gluon interactions,” said Massachusetts Institute of Technology physicist Gunther Roland, a longtime RHIC and LHC collaborator and now a co-spokesperson for the new collaboration..

    Brookhaven physicist Dave Morrison, the other co-spokesperson, agrees: “On the one hand we have a very successful theory that describes the quarks and gluons as free point-like particles. On the other hand, we have a whole set of measurements that describe the collective properties of the QGP. What we’d like to do is connect the two—the microscopic to the not-so-microscopic.”

    For now, the collaboration goes by the name sPHENIX: “s” for its focus on the strongly interacting particles and PHENIX for the anticipated use of key detector components and that experiment’s location in the RHIC ring once the existing PHENIX systems complete their data-taking lifetime at the end of this year’s run. But the collaboration leaders emphasize that there’s no need for members to be previously affiliated with PHENIX—or indeed with prior research at RHIC.

    “This is a new collaboration, and, if we get the go-ahead for this upgrade, this detector will have brand new capabilities,” Morrison said.

    2
    A schematic of the proposed sPHENIX detector, showing several key components: outer and inner hadronic calorimeters (HCal), electromagnetic (EM) calorimeter, tracking systems, and coils of the superconducting solenoid magnet

    BNL/RHIC Phenix

    BNL/ Phenix
    BNL/ Phenix another view

    Tracking probes from within the plasma

    Figuring out how the QGP’s properties emerge from its smallest particles requires a detector that can make more—and more precise—measurements of what’s going on in the plasma at different length scales.

    “Think about looking at a pond that behaves like a liquid,” Morrison explained. “You might see waves and flowing water. If you had a microscope that could dial down, at some point you would see water molecules—the particles that make up the water. If you know a lot about those particles and how they behave, you can try to understand how the properties of the pond arise from the properties of the molecules. That’s what we’d like to do with the QGP.”

    Particle detectors are the microscopes nuclear physicists use to dive down into the details of subatomic matter. But instead of shining visible light, electrons, or x-rays on the sample, particle detectors pick up signals from particles created within the collisions. Measuring how these particles move through and lose energy by interacting with the plasma will reveal information about the QGP at scales between the level of individual quarks and the long-scale collective behavior.

    “There has to be an evolution from the short-wavelength behavior to the long-wavelength behavior, and we want to probe that transition,” Roland said.

    Fast detector for precision measurements

    One set of particles sPHENIX physicists are interested in tracking are upsilons—each made of two heavy quarks bound together. Each different bound state has a different mass. The sPHENIX scientists want to understand how upsilons with different masses form and disassociate and otherwise interact with the plasma.

    They’re also interested in analyzing collimated streams of particles called jets—created as the energy of individual fast-moving quarks and gluons is transformed into a cascade of new particles. Measuring how much energy is lost by higher- and lower-energy jets will convey information about both the individual particle scale deep within the plasma and its long-range characteristics.

    “The higher the momentum, the more rarely it is produced. So you need a very fast detector that can capture a lot of collisions to increase the chances of spotting these important events,” Roland said.

    By removing outdated components from PHENIX and replacing them with new, custom-designed systems, the sPHENIX collaboration would transform that experiment into a “new” state-of-the-art detector that can capture as many as 15,000 events per second—a significant increase over STAR’s current capture rate of 2,000 events per second, or PHENIX’s 5,000—with all the components needed to differentiate among the three mass states of upsilons and tease apart the full energy scale of jets.

    “This transformed detector would be suited to record a huge fraction of what RHIC can produce,” Morrison said.

    Testing essential detector components

    Physicists and engineers at Brookhaven and elsewhere have already begun building prototypes and testing components that could be used to achieve the anticipated transformation. And this endeavor is attracting a new generation of physicists eager to get in on the ground floor of a new experiment.

    “I worked on PHENIX as grad student at Stony Brook University. Then, as a postdoc at Yale, I worked on the ALICE experiment at the LHC,” said Megan Connors, a RIKEN-BNL Research Center Fellow at Brookhaven Lab who will begin teaching and forming her own research group at Georgia State University next year. “When I came on the scene, both colliders were already up and running. So this is a chance to be involved from the start—to see how these experiments come to life, to be part of the formation of the collaboration and get involved in building the hardware in addition to analyzing the data.”

    3
    Megan Connors and Anne Sickles checking out calorimeter components at Brookhaven Lab.

    The piece of hardware that currently has her attention is a prototype “calorimeter” that would track and reconstruct the sprays of particles that make up jets, which recently underwent extensive testing at Fermi National Accelerator Laboratory.

    “A typical jet may contain 10 or 15 particles, but you need to tease those out from the hundreds of particles coming out of a heavy ion collision event,” Connors said. “And you need to capture all the particles to be able to reconstruct the jet and see how much energy it loses as it travels through the plasma.”

    You also need to know how much energy the jet had to start with. Most of the time jets are formed in back-to-back pairs. Both jets lose energy in the plasma. However sometimes, instead, a particle of light called a photon gets produced back-to-back with a jet. But unlike the jet particles, the photon shooting off in the opposite direction does not interact with the quarks and gluons in the plasma, so it doesn’t lose any energy.

    “If you have a photon going one way, and a jet going the other way, the jet and the photon had the same starting energy,” explained Anne Sickles, an sPHENIX collaborator from the University of Illinois at Urbana-Champaign who was also involved in the calorimeter design and testing. “So measuring the photon’s energy gives you the starting point. Measuring the particles that make up the jet and subtracting from the photon energy tells you how much energy the jet lost.”

    Using Fermilab’s Test Beam Facility, Sickles and some of her students shot a beam of electrons through portions of an “electromagnetic” calorimeter they designed to track photons and some of the other particles that make up jets. For the initial tests, the electrons—pure electromagnetic particles like photons—served as stand-ins for the photons. The aim of the tests was to be sure all areas of the detector respond in a similar way, and that there’s no variation between pieces built by Sickles and her students in Illinois and pieces constructed by an outside contractor.

    Next, the physicists added components of a “hadronic” calorimeter for tracking hadrons (particles made of more than one quark), which Connors and her team had been working on. They placed the hadron detectors directly behind the electromagnetic calorimeter—just as the two components will be arranged in the actual detector. This outer layer is designed to catch the larger hadron particles that make it through the first layer so physicists can account for the full energy of each jet.

    Building the calorimeter thick enough to “catch” all the particles is one way that the design of sPHENIX benefits from the 16 years of operating RHIC and several years experience at LHC.

    “Before RHIC was built, we didn’t even know how many particles would be produced. We had to build the detectors to cover a wide range of possibilities,” Morrison said. “Now, knowing what the collisions look like and the kinds of particles produced, we can build a detector tailored to do the measurements that are focused on the specific important questions we’d like to answer.”

    Mighty magnet

    Testing is also underway on a 20-ton solenoid magnet acquired from a former physics experiment at DOE’s SLAC National Accelerator Laboratory. This magnet would form the heart of the sPHENIX detector, completely surrounding the collision zone like the cylindrical magnet at the center of RHIC’s STAR detector. Like STAR’s, the sPHENIX magnet would bend the trajectories of charged particles as they emerge from the collisions. But with three times the bending power of STAR, sPHENIX should be able to separate out the signals from the three types of upsilon particles, whose masses differ by only a few percent.

    “Upsilons don’t make it all the way to the magnet,” Morrison explained. “These are heavy particles that decay, often into an electron and an antielectron, which have a lot of energy when they come out. You need a powerful magnetic field to bend these charged particles so you can get a better measurement of their velocity and momentum, and tease out small differences to separate the electrons that come from the different-size upsilons.”

    So far, a team of engineers and physicists in Brookhaven’s Superconducting Magnet Division, Collider-Accelerator Department, and Physics Department has cooled the superconducting magnet down to its near-absolute-zero operating temperature of 4.2 Kelvin and tested it with 100 amperes of current.

    “We needed to test the overall health and integrity of the magnet to make sure all the joints and couplings are in place, in case they got jostled while being transported cross-country,” said lead magnet engineer Piyush Joshi. They also tested systems Joshi designed to shut the magnet down in a controlled manner if the field between the magnet’s two layers of coils ever gets out of balance. “You want to detect any imbalance very quickly so you can extract the energy before it causes any damage to the magnet,” he said. He originally wrote the algorithms for an LHC magnet project, but they proved to be just as useful for the sPHENIX tests.

    With the initial, low-field tests complete, the group will next use steel recycled from another older experiment at Brookhaven to surround the magnet to contain its most powerful field—and ramp it up to a full 4,600 amps.

    5
    Engineers and physicists involved in testing the 20-ton superconducting solenoid expected to form the heart of the sPHENIX upgrade: Kin Yip, Collider-Accelerator Department (CAD); Piyush Joshi, Superconducting Magnet Division (SMD); Richard Meier, CAD cryo group; Brian Van Kuik, CAD main control room operations coordinator; Ray Ceruti, SMD; Sonny Dimaiuta, SMD; Dominick Milidantri, SMD.

    Path forward

    By reusing equipment and tools developed with funding for RHIC and the LHC, and inspiring university collaborators to chip in their expertise, the nascent collaboration has taken these early steps on the path toward transforming PHENIX into sPHENIX. But the team hopes to get an official seal of approval—and, eventually, a budget—from DOE.

    The 2015 Long Range Plan for Nuclear Science—a set of recommendations made by the nation’s Nuclear Science Advisory Committee to leaders at DOE and the National Science Foundation—identifies the sPHENIX “state-of-the-art jet detector” as “essential” to probing the inner workings of QGP at shorter and shorter length scales, one of two “central goals” noted in the report for completing the scientific mission at RHIC. The report also notes that there is significant international interest in sPHENIX.

    “Right now we have a collaboration of 183 people, and growing,” Morrison said, with those scientists representing 58 institutions in 10 countries.

    Looking ahead and continuing the tradition of making the most of our nation’s investments in science, the physicists designing the sPHENIX upgrades say this transformed detector could largely be reused as a detector for a future Electron Ion Collider—the next priority nuclear physics project identified in the Long Range Plan.

    “Transforming PHENIX into sPHENIX would maximize the benefits derived from the investments already made to build RHIC by allowing us to fully understand the quark-gluon plasma,” Morrison said. “It’s what we need to do to complete the story of QGP discovery and to prepare for the coming research directions in nuclear physics.”

    sPHENIX R&D is supported by the DOE Office of Science and also by Brookhaven Lab’s Laboratory Directed Research and Development program, BNL Program Development, and in-kind contributions from collaborating universities.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition
    BNL Campus

    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.
    i1

     
  • richardmitnick 9:39 am on February 16, 2016 Permalink | Reply
    Tags: , , BNL PHENIX, , Gluon importance, Proton Spin   

    From BNL: “Physicists Zoom in on Gluons’ Contribution to Proton Spin” 

    Brookhaven Lab

    February 16, 2016
    Karen McNulty Walsh

    Latest data from high-energy proton collisions at RHIC indicate that “wimpy” gluons have a big impact on proton spin, and gluons overall may contribute more than quarks

    Brookhaven Phenix
    The PHENIX detector at the Relativistic Heavy Ion Collider (RHIC), a particle accelerator at Brookhaven National Laboratory uniquely capable of measuring how a proton’s internal building blocks — quarks and gluons — contribute to its overall intrinsic angular momentum, or “spin.”

    By analyzing the highest-energy proton collisions at the Relativistic Heavy Ion Collider (RHIC), a particle collider at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory, nuclear physicists have gotten a glimpse of how a multitude of gluons that individually carry very little of the protons’ overall momentum contribute to the protons’ spin. The data described in a recently published paper indicate that these glue-like particles—named for their role in binding the quarks that make up each proton—play a substantial role in determining the intrinsic angular momentum, or spin, of these building blocks of matter.

    “These results confirm our suspicion that a lot of the gluons’ contribution to proton spin comes from the gluons with relatively low momentum,” said Ralf Seidl, a physicist from the RIKEN-BNL Research Center (RBRC) and a member of RHIC’s PHENIX collaboration, which published these results. The results also suggest that gluons’ overall contribution to spin might be even greater than the contribution from quarks.

    Exploring the sources of proton spin is one of the major scientific missions at RHIC, a DOE Office of Science User Facility and the only machine in the world capable of colliding protons with their spins aligned in a chosen direction.

    BNL RHIC Campus
    Proton Spin BNL PHENIX
    RHIC is the only machine in the world that can collide protons with their spins aligned in a particular direction. Measuring differences in the particles produced when the spins in the two beams are pointing at one another (as shown) vs. when they are pointing in the same direction, colliding “head” to “tail,” can help scientists tease out the contribution made by gluons.

    Nuclear physicists from around the globe, including many supported by the Japanese RIKEN laboratory, come to RHIC to study these “polarized proton” collisions in an effort to solve the so-called proton spin puzzle. The RBRC was established at Brookhaven in collaboration with RIKEN to support young scientists engaged in this and other relevant research.

    The proton spin mystery originated when experiments in the 1980s revealed that a proton’s spin—a property that influences these particles’ optical, electrical, and magnetic characteristics—does not come solely from its quarks. To tease out the gluons’ role, RHIC physicists collide two beams of protons with their spins aligned in the same direction, and then with the polarization of one beam flipped so the spins are “antialigned.” The PHENIX detector measures the number of particles called pions that come out of the collision zone perpendicular to the colliding beams under these two conditions. Any difference observed in the production of these pions between the two conditions is an indication of how much the gluons’ spins are aligned with, and therefore contribute to, the spin of the proton.

    Results reported in 2014 indicated that gluons definitely play a significant role, but the uncertainty about the size of their contribution was fairly large. Both the energy of the collisions and the angles at which RHIC’s detectors were measuring limited the range of gluons those experiments could explore.

    The new data come from collisions at a much higher energy—500 billion electron volts (GeV) as compared to the earlier 200 GeV data.

    “This higher collision energy allows us to extend the ‘kinematic range’ to look at the contributions of gluons that carry a lower fraction of the overall momentum of the proton,” said Seidl. “It sounds contradictory at first, but as the collision energy goes up, the ‘momentum fraction’ of the gluons whose contribution you are measuring goes down.”

    You can think of it like a microscope, explained John Lajoie, a PHENIX collaborator from Iowa State University. “Going to higher energy allows you to focus on smaller objects. In this case the smaller object is the lower-momentum-fraction gluons.”

    The data show that these “wimpy” gluons play an outsized role in contributing to proton spin. The reason, the physicists say, is that there are so many of them.

    “The density of gluons increases very rapidly for very low momentum fractions,” Seidl said.

    Using the microscope analogy again, “the more we zoom in, the more ‘quantum fluctuations’ we can observe,” said Lajoie, referring to the whimsical tendency of subatomic particles to split and transform. “Inside the proton, there’s a sea of quarks and antiquarks and gluons changing and evolving. When you look with one resolution you see a certain number, but looking closer you can see that some of these particles have split, so there are actually more gluons there.”

    The measurements of low-momentum-fraction gluon polarization, and these particles’ large contribution to overall proton spin, have reduced the uncertainties about the overall size of the gluon contribution to spin somewhat. While the previous results indicated that gluons might contribute about as much as the quarks and antiquarks, the new findings may bring the gluons’ total contribution a bit higher.

    “Large uncertainties remain and there’s room for improvement in these measurements,” Seidl said. There are also other ways to look for contributions from even lower-momentum-fraction gluons, including exploring particles emerging from collisions at more “forward” angles. “Extending the momentum fraction range even further to lower values is one of the remaining goals of the RHIC spin program,” Seidl said.

    It’s also one reason nuclear physicists would like to build an electron ion collider (EIC), a machine that would use an electron beam to probe the internal structure of the proton even more directly.

    “An EIC would allow us to make numerous, extremely precise measurements across a much wider range of momentum fractions,” said Brookhaven physicist Elke Aschenauer, a leader in the spin program at RHIC. “It would be the only facility in the world that could measure the distribution of polarized gluons as a function of their momentum and also their spatial distribution in the proton—like a microscope that resolves even the smallest features very precisely.”

    A recent report from the U.S. Nuclear Science Advisory Committee ranked an EIC as its top priority for new facility construction once another construction project already underway is complete. So scientists may get their wish of being able to see gluons precisely enough to finally resolve the spin mystery.

    Research at RHIC is supported by the DOE Office of Science (NP) and these agencies and organizations.

    Brookhaven National Laboratory is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition
    BNL Campus

    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.
    i1

     
  • richardmitnick 4:43 pm on September 10, 2015 Permalink | Reply
    Tags: , BNL PHENIX, , ,   

    From BNL: “Tiny Drops of Early Universe ‘Perfect’ Fluid” 

    Brookhaven Lab

    August 31, 2015
    Karen McNulty Walsh, (631) 344-8350 or Peter Genzer, (631) 344-3174

    1
    The upper panel of this image, created based on calculations by Brookhaven Lab nuclear theorist Bjoern Schenke, represents initial hot spots created by collisions of one, two, and three-particle ions with heavy nuclei. The lower panel shows the geometrical patterns of particle flow that would be expected if the small-particle collisions are creating tiny hot spots of quark-gluon plasma. No image credit.

    The Relativistic Heavy Ion Collider (RHIC), a particle collider for nuclear physics research at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory, smashes large nuclei together at close to the speed of light to recreate the primordial soup of fundamental particles that existed in the very early universe.

    BNL RHIC Campus
    BNL RHIC

    Experiments at RHIC—a DOE Office of Science User Facility that attracts more than 1,000 collaborators from around the world—have shown that this primordial soup, known as quark-gluon plasma (QGP), flows like a nearly friction free “perfect” liquid. New RHIC data just accepted for publication in the journal Physical Review Letters now confirm earlier suspicions that collisions of much smaller particles can also create droplets of this free-flowing primordial soup, albeit on a much smaller scale, when they collide with the large nuclei.

    “These tiny droplets of quark-gluon plasma were at first an intriguing surprise,” said Berndt Mueller, Associate Laboratory Director for Nuclear and Particle Physics at Brookhaven. “Physicists initially thought that only the nuclei of large atoms such as gold would have enough matter and energy to set free the quark and gluon building blocks that make up protons and neutrons. But the flow patterns detected by RHIC’s PHENIX collaboration in collisions of helium-3 nuclei with gold ions now confirm that these smaller particles are creating tiny samples of perfect liquid QGP.”

    These results build on earlier findings from collisions of two-particle ions known as deuterons with gold ions at RHIC, as well as proton-lead and proton-proton collisions at Europe’s Large Hadron Collider (LHC).

    CERN LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC at CERN

    They also set the stage for the current run colliding protons with gold at RHIC.

    “The idea that collisions of small particles with larger nuclei might create minute droplets of primordial quark-gluon plasma has guided a series of experiments to test this idea and alternative explanations, and stimulated a rich debate about the implications of these findings,” said University of Colorado physicist Jamie Nagle, a co-spokesperson of the PHENIX collaboration at RHIC. “These experiments are revealing the key elements required for creating quark-gluon plasma and could also offer insight into the initial state characteristics of the colliding particles.”

    Geometrical flow patterns

    2
    RHIC’s PHENIX detector

    The discovery of the “perfect” liquid at RHIC, announced definitively in 2005, was largely based on observations of particles flowing in an elliptical pattern from the matter created in RHIC’s most energetic gold-gold collisions. This flow was a clear sign that particles emerging from the collisions were behaving in a correlated, or collective, way that contrasted dramatically with the uniformly expanding gas the scientists had expected. Additional experiments confirmed that this liquid is indeed composed of visible matter’s most fundamental building blocks, quarks and gluons, no longer confined within individual protons and neutrons, and that the flow occurs with minimal resistance—making it a nearly “perfect” liquid QGP.

    “Experiments colliding smaller particles with the heavy ions were originally designed as control experiments because they weren’t supposed to create the QGP,” Nagle said. “But observations at the LHC of very energetic proton-proton collisions and later experiments there colliding protons with lead revealed hints that particles streaming from those tiny collisions were also behaving collectively and flowing. It looked a lot like some of the perfect liquid signatures originally discovered in gold-gold collisions at RHIC, and later in lead-lead collisions at the LHC.”

    When RHIC physicists checked data from the RHIC run of 2008, when deuterons (a nucleus made of one proton and one neutron) were smashed into gold ions, they saw a similar pattern.

    “Since the deuteron is two particles, it creates two separate impacts on the nucleus—two hot spots that appear to merge and form an elongated drop of QGP,” Nagle said.

    Definitive tests

    Those observations triggered the idea of testing for flow patterns in a range of more tightly controlled experiments, which is only possible at RHIC, where physicists can collide a wide variety of ions to control the shape of the droplets of matter created. With additional deuteron-gold collisions already in hand, the RHIC scientists set out to collide three-particle helium-3 nuclei (each made of two protons and one neutron) with gold—and later, single protons with gold.

    “The PHENIX detector can pick up particles coming out of collisions very far forward and backward from the collision point. This large angle coverage allows us to measure the flow in these small collision systems,” said Shengli Huang, a PHENIX collaborator from Vanderbilt University who carried out the analysis. “PHENIX also has a trigger detector that picks up and records the most violent collisions—the ones in which the flow pattern is most apparent,” he said.

    The analysis of those events, as described in the new paper, reveals that the helium-gold collisions exhibit a triangular pattern of flow that the scientists say is consistent with the creation of three tiny droplets of QGP. They also say the data indicate that these small particle collisions could be producing the extreme temperatures required to free quarks and gluons—albeit at a much smaller, more localized scale than in the relatively big domains of QGP created in collisions of two heavy ions.

    “This is a pretty definitive measurement,” Nagle said. “The paper has a plot of elliptical and triangular flow that pretty much matches the hydrodynamic flow calculations we’d expect for QGP. We are really engineering different shapes of the QGP to manipulate it and see how it behaves.”

    There are other key signatures of QGP formation, such as the stopping of energetic particle jets, which have not been detected in the tiny droplets. And other theoretical explanations suggest the flow patterns resulting from some of the small particle-nucleus collisions could emerge from the interactions of gluons within the colliding particles, rather than from the formation of QGP.

    “At this time, the only theoretical framework that reproduces the patterns we’re observing in deuteron-gold and helium-3-gold collisions is fluid dynamics,” said Bjoern Schenke, a nuclear theorist at Brookhaven Lab. “It remains to be seen if alternative models can describe these patterns as well.”

    If other models also turn out to be compatible with the helium-3-gold data, physicists will want to explore whether these models make predictions that differ from those of the hydrodynamic flow model, and for which types of collisions.

    “The good news is that RHIC, with its unrivaled versatility, will likely be able to study any system that can discriminate between different models,” Mueller said.

    Research at RHIC is funded primarily by the DOE Office of Science.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition
    BNL Campus

    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.
    i1

     
  • richardmitnick 8:46 am on September 4, 2015 Permalink | Reply
    Tags: , , BNL PHENIX, , ,   

    From BNL: “Tiny Drops of Early Universe ‘Perfect’ Fluid” 

    Brookhaven Lab

    August 31, 2015
    Karen McNulty Walsh, (631) 344-8350 or Peter Genzer, (631) 344-3174

    1
    The upper panel of this image represents initial hot spots created by collisions of one, two, and three-particle ions with heavy nuclei. The lower panel shows the geometrical patterns of particle flow that would be expected if the small-particle collisions are creating tiny hot spots of quark-gluon plasma.

    The Relativistic Heavy Ion Collider (RHIC), a particle collider for nuclear physics research at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory, smashes large nuclei together at close to the speed of light to recreate the primordial soup of fundamental particles that existed in the very early universe.

    BNL RHIC Campus
    BNL RHIC

    RHIC

    Experiments at RHIC—a DOE Office of Science User Facility that attracts more than 1,000 collaborators from around the world—have shown that this primordial soup, known as quark-gluon plasma (QGP), flows like a nearly friction free “perfect” liquid. New RHIC data just accepted for publication in the journal Physical Review Letters now confirm earlier suspicions that collisions of much smaller particles can also create droplets of this free-flowing primordial soup, albeit on a much smaller scale, when they collide with the large nuclei.

    “These tiny droplets of quark-gluon plasma were at first an intriguing surprise,” said Berndt Mueller, Associate Laboratory Director for Nuclear and Particle Physics at Brookhaven. “Physicists initially thought that only the nuclei of large atoms such as gold would have enough matter and energy to set free the quark and gluon building blocks that make up protons and neutrons. But the flow patterns detected by RHIC’s PHENIX collaboration in collisions of helium-3 nuclei with gold ions now confirm that these smaller particles are creating tiny samples of perfect liquid QGP.”

    These results build on earlier findings from collisions of two-particle ions known as deuterons with gold ions at RHIC, as well as proton-lead and proton-proton collisions at Europe’s Large Hadron Collider (LHC).

    CERN LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC at CERN

    They also set the stage for the current run colliding protons with gold at RHIC.

    “The idea that collisions of small particles with larger nuclei might create minute droplets of primordial quark-gluon plasma has guided a series of experiments to test this idea and alternative explanations, and stimulated a rich debate about the implications of these findings,” said University of Colorado physicist Jamie Nagle, a co-spokesperson of the PHENIX collaboration at RHIC. “These experiments are revealing the key elements required for creating quark-gluon plasma and could also offer insight into the initial state characteristics of the colliding particles.”

    Geometrical flow patterns

    2
    Relativistic Heavy Ion Collider’s PHENIX detector

    The discovery of the “perfect” liquid at RHIC, announced definitively in 2005, was largely based on observations of particles flowing in an elliptical pattern from the matter created in RHIC’s most energetic gold-gold collisions. This flow was a clear sign that particles emerging from the collisions were behaving in a correlated, or collective, way that contrasted dramatically with the uniformly expanding gas the scientists had expected. Additional experiments confirmed that this liquid is indeed composed of visible matter’s most fundamental building blocks, quarks and gluons, no longer confined within individual protons and neutrons, and that the flow occurs with minimal resistance—making it a nearly “perfect” liquid QGP.

    “Experiments colliding smaller particles with the heavy ions were originally designed as control experiments because they weren’t supposed to create the QGP,” Nagle said. “But observations at the LHC of very energetic proton-proton collisions and later experiments there colliding protons with lead revealed hints that particles streaming from those tiny collisions were also behaving collectively and flowing. It looked a lot like some of the perfect liquid signatures originally discovered in gold-gold collisions at RHIC, and later in lead-lead collisions at the LHC.”

    When RHIC physicists checked data from the RHIC run of 2008, when deuterons (a nucleus made of one proton and one neutron) were smashed into gold ions, they saw a similar pattern.

    “Since the deuteron is two particles, it creates two separate impacts on the nucleus—two hot spots that appear to merge and form an elongated drop of QGP,” Nagle said.

    Definitive tests

    Those observations triggered the idea of testing for flow patterns in a range of more tightly controlled experiments, which is only possible at RHIC, where physicists can collide a wide variety of ions to control the shape of the droplets of matter created. With additional deuteron-gold collisions already in hand, the RHIC scientists set out to collide three-particle helium-3 nuclei (each made of two protons and one neutron) with gold—and later, single protons with gold.

    “The PHENIX detector can pick up particles coming out of collisions very far forward and backward from the collision point. This large angle coverage allows us to measure the flow in these small collision systems,” said Shengli Huang, a PHENIX collaborator from Vanderbilt University who carried out the analysis. “PHENIX also has a trigger detector that picks up and records the most violent collisions—the ones in which the flow pattern is most apparent,” he said.

    The analysis of those events, as described in the new paper, reveals that the helium-gold collisions exhibit a triangular pattern of flow that the scientists say is consistent with the creation of three tiny droplets of QGP. They also say the data indicate that these small particle collisions could be producing the extreme temperatures required to free quarks and gluons—albeit at a much smaller, more localized scale than in the relatively big domains of QGP created in collisions of two heavy ions.

    “This is a pretty definitive measurement,” Nagle said. “The paper has a plot of elliptical and triangular flow that pretty much matches the hydrodynamic flow calculations we’d expect for QGP. We are really engineering different shapes of the QGP to manipulate it and see how it behaves.”

    There are other key signatures of QGP formation, such as the stopping of energetic particle jets, which have not been detected in the tiny droplets. And other theoretical explanations suggest the flow patterns resulting from some of the small particle-nucleus collisions could emerge from the interactions of gluons within the colliding particles, rather than from the formation of QGP.

    “At this time, the only theoretical framework that reproduces the patterns we’re observing in deuteron-gold and helium-3-gold collisions is fluid dynamics,” said Bjoern Schenke, a nuclear theorist at Brookhaven Lab. “It remains to be seen if alternative models can describe these patterns as well.”

    If other models also turn out to be compatible with the helium-3-gold data, physicists will want to explore whether these models make predictions that differ from those of the hydrodynamic flow model, and for which types of collisions.

    “The good news is that RHIC, with its unrivaled versatility, will likely be able to study any system that can discriminate between different models,” Mueller said.

    Research at RHIC is funded primarily by the DOE Office of Science and also by these agencies and organizations.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition
    BNL Campus

    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.
    i1

     
c
Compose new post
j
Next post/Next comment
k
Previous post/Previous comment
r
Reply
e
Edit
o
Show/Hide comments
t
Go to top
l
Go to login
h
Show/Hide help
shift + esc
Cancel
%d bloggers like this: