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

    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

    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

    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 .

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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 10:26 am on July 23, 2015 Permalink | Reply
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    From Rice: “Rice physicists find surprising ‘liquid-like’ particle interactions in Large Hadron Collider” 

    Rice U bloc

    Rice University

    July 22, 2015

    Don Lincoln

    Three years ago, Rice physicists and their colleagues on the Large Hadron Collider’s (LHC’s) Compact Muon Solenoid (CMS) experiment stumbled on an unexpected phenomenon.

    CERN CMS Detector

    Physicists smashed protons into lead nuclei at nearly the speed of light, which caused hundreds of particles to erupt from these collisions. But that wasn’t the surprise. What was surprising is where these particles went: Rather than spreading out evenly in all directions, the particles coming out of the collisions preferentially lined up in a specific direction.

    Now, the Rice team has co-authored a paper that describes the unexpected particle interactions from these proton and lead-nuclei collisions.

    Rice undergraduate student Benjamin Tran, graduate student Michael Northup, postdoctoral student Maxime Guilbaud and graduate students Zhenyu Chen and Zhoudunming Tu were part of the Rice team of physicists on the Large Hadron Collider’s Compact Muon Solenoid experiment that co-authored a paper describing the unexpected particle interactions from proton and lead-nuclei collisions. (Photo by Zhoudunming Tu)

    Particle detectors are shaped a little like a soup can. In these kinds of collisions, there is a tendency for particles to amass in a line along the axis of the can known as a “ridge.” Up until now, physicists understood a lot about what happens when a pair of protons or a pair of lead nuclei collide, but not a lot about what happens when a proton hits a lead nucleus: Would the hot nuclear matter coming out of the collision act like protons colliding, in which the post-collision particles coast along without feeling the effect of their neighbors? Or would the particles coming out of proton and lead collisions act in a more collective, liquid-like way as in lead-nuclei collisions?

    In the recent Physical Review Letters paper, Rice physicists and co-authors returned to this mystery with more data than ever before. Physics Professor Wei Li, who discovered the phenomenon, led the team of scientists who analyzed the new data. They found that the data strongly supported that the matter coming out of these proton and lead collisions acts more like a liquid. This result was surprising because when the proton hits the lead nucleus, it punches a hole through much of the nucleus, like shooting a rifle at a watermelon (as opposed to colliding two lead nuclei, which is like slamming two watermelons together). Wei and his collaborators studied this surprising behavior by looking at six or eight particles simultaneously and how their directions correlated. This method is far more sensitive for identifying liquid-like behavior than the older method, which looked at particles two at a time. Li’s group also developed an algorithm called a trigger that records a small number of important collisions in the CMS detector among billions of candidates, allowing the researchers to efficiently investigate this interesting phenomenon.

    The data used in this analysis was recorded in March 2013 before the LHC stopped operations for refurbishments, retrofits and upgrades. This past June the LHC resumed operations with a 60 percent increase in collision energy. In December of this year, Li’s group will reconfigure the LHC accelerator to collide lead nuclei and see what sort of surprises this increase in collision energy will bring.

    This study helps scientists characterize a state of matter called a “quark-gluon plasma,” or QGP. This is similar to the familiar solid, liquid and gaseous states of matter, but much hotter. A QGP occurs when matter is heated to temperatures high enough to literally melt protons and neutrons at the center of atomic nuclei; the last time that a QGP was common in the universe was a mere millionth of a second after the Big Bang. The liquid-like nature of the QGP was a surprise to scientists, as they predicted a more gaseous-like behavior. Learning more about quark-gluon plasma will teach us something significant about the birth of the universe itself.

    See the full article here.

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    Rice U campus

    In his 1912 inaugural address, Rice University president Edgar Odell Lovett set forth an ambitious vision for a great research university in Houston, Texas; one dedicated to excellence across the range of human endeavor. With this bold beginning in mind, and with Rice’s centennial approaching, it is time to ask again what we aspire to in a dynamic and shrinking world in which education and the production of knowledge will play an even greater role. What shall our vision be for Rice as we prepare for its second century, and how ought we to advance over the next decade?

    This was the fundamental question posed in the Call to Conversation, a document released to the Rice community in summer 2005. The Call to Conversation asked us to reexamine many aspects of our enterprise, from our fundamental mission and aspirations to the manner in which we define and achieve excellence. It identified the pressures of a constantly changing and increasingly competitive landscape; it asked us to assess honestly Rice’s comparative strengths and weaknesses; and it called on us to define strategic priorities for the future, an effort that will be a focus of the next phase of this process.

  • richardmitnick 1:00 pm on June 8, 2015 Permalink | Reply
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    From BNL: “Scientists See Ripples of a Particle-Separating Wave In Primordial Plasma” 

    Brookhaven Lab

    June 8, 2015
    Karen McNulty Walsh

    Key sign of quark-gluon plasma (QGP) and evidence for a long-debated quantum phenomenon

    Off-center collisions of gold ions create a strong magnetic field and set up a series of effects that push positively charged particles to the poles of the football-shaped collision zone and negatively charged particles to the “equator.” This charge separation is evidence for the existence of a “chiral magnetic wave” formed in the quark-gluon plasma created at RHIC.

    Scientists in the STAR collaboration at the Relativistic Heavy Ion Collider (RHIC), a particle accelerator exploring nuclear physics and the building blocks of matter at the U.S. Department of Energy’s Brookhaven National Laboratory, have new evidence for what’s called a “chiral magnetic wave” rippling through the soup of quark-gluon plasma created in RHIC’s energetic particle smashups.

    The presence of this wave is one of the consequences scientists were expecting to observe in the quark-gluon plasma—a state of matter that existed in the early universe when quarks and gluons, the building blocks of protons and neutrons, were free before becoming inextricably bound within those larger particles. The tentative discovery, if confirmed, would provide additional evidence that RHIC’s collisions of energetic gold ions recreate nucleus-size blobs of the fiery plasma thousands of times each second. It would also provide circumstantial evidence in support of a separate, long-debated quantum phenomenon required for the wave’s existence. The findings are described in a paper that will be highlighted as an Editors’ Suggestion in Physical Review Letters.

    To try to understand these results, let’s take a look deep within the plasma to a seemingly surreal world where magnetic fields separate left- and right-“handed” particles, setting up waves that have differing effects on how negatively and positively charged particles flow.

    “What we measure in our detector is the tendency of negatively charged particles to come out of the collisions around the ‘equator’ of the fireball, while positively charged particles are pushed to the poles,” said STAR collaborator Hongwei Ke, a postdoctoral fellow at Brookhaven. But the reasons for this differential flow, he explained, begin when the gold ions collide.

    The ions are gold atoms stripped of their electrons, leaving 79 positively charged protons in a naked nucleus. When these ions smash into one another even slightly off center, the whole mix of charged matter starts to swirl. That swirling positive charge sets up a powerful magnetic field perpendicular to the circulating mass of matter, Ke explained. Picture a spinning sphere with north and south poles.

    Within that swirling mass, there are huge numbers of subatomic particles, including quarks and gluons at the early stage, and other particles at a later stage, created by the energy deposited in the collision zone. Many of those particles also spin as they move through the magnetic field. The direction of their spin relative to their direction of motion is a property called chirality, or handedness; a particle moving away from you spinning clockwise would be right-handed, while one spinning counterclockwise would be left-handed.

    The STAR detector at RHIC tracks particles emerging from thousands of subatomic smashups per second.

    According to Gang Wang, a STAR collaborator from the University of California at Los Angeles, if the numbers of particles and antiparticles are different, the magnetic field will affect these left- and right-handed particles differently, causing them to separate along the axis of the magnetic field according to their “chiral charge.”

    “This ‘chiral separation’ acts like a seed that, in turn, causes particles with different charges to separate,” Gang said. “That triggers even more chiral separation, and more charge separation, and so on—with the two effects building on one another like a wave, hence the name ‘chiral magnetic wave.’ In the end, what you see is that these two effects together will push more negative particles into the equator and the positive particles to the poles.”

    To look for this effect, the STAR scientists measured the collective motion of certain positively and negatively charged particles produced in RHIC collisions. They found that the collective elliptic flow of the negatively charged particles—their tendency to flow out along the equator—was enhanced, while the elliptic flow of the positive particles was suppressed, resulting in a higher abundance of positive particles at the poles. Importantly, the difference in elliptic flow between positive and negative particles increased with the net charge density produced in RHIC collisions.

    According to the STAR publication, this is exactly what is expected from calculations using the theory predicting the existence of the chiral magnetic wave. The authors note that the results hold out for all energies at which a quark-gluon plasma is believed to be created at RHIC, and that, so far, no other model can explain them.

    The finding, says Aihong Tang, a STAR physicist from Brookhaven Lab, has a few important implications.

    “First, seeing evidence for the chiral magnetic wave means the elements required to create the wave must also exist in the quark-gluon plasma. One of these is the chiral magnetic effect—the quantum physics phenomenon that causes the electric charge separation along the axis of the magnetic field—which has been a hotly debated topic in physics. Evidence of the wave is evidence that the chiral magnetic effect also exists.” Tang said.

    The chiral magnetic effect is also related to another intriguing observation at RHIC of more-localized charge separation within the quark-gluon plasma. So this new evidence of the wave provides circumstantial support for those earlier findings.

    Finally, Tang pointed out that the process resulting in propagation of the chiral magnetic wave requires that “chiral symmetry”—the independent identities of left- and right-handed particles—be “restored.”

    “In the ‘ground state’ of quantum chromodynamics (QCD)—the theory that describes the fundamental interactions of quarks and gluons—chiral symmetry is broken, and left- and right-handed particles can transform into one another. So the chiral charge would be eliminated and you wouldn’t see the propagation of the chiral magnetic wave,” said nuclear theorist Dmitri Kharzeev, a physicist at Brookhaven and Stony Brook University. But QCD predicts that when quarks and gluons are deconfined, or set free from protons and neutrons as in a quark-gluon plasma, chiral symmetry is restored. So the observation of the chiral wave provides evidence for chiral symmetry restoration—a key signature that quark-gluon plasma has been created.

    “How does deconfinement restore the symmetry? This is one of the main things we want to solve,” Kharzeev said. “We know from the numerical studies of QCD that deconfinement and restoration happen together, which suggests there is some deep relationship. We really want to understand that connection.”

    Brookhaven physicist Zhangbu Xu, spokesperson for the STAR collaboration, added, “To improve our ability to search for and understand the chiral effects, we’d like to compare collisions of nuclei that have the same mass number but different numbers of protons—and therefore, different amounts of positive charge (for example, Ruthenium, mass number 96 with 44 protons, and Zirconium, mass number 96 with 40 protons). That would allow us to vary the strength of the initial magnetic field while keeping all other conditions essentially the same.”

    See the full article here.

    Please help promote STEM in your local schools.

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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 6:09 am on May 8, 2015 Permalink | Reply
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    From FNAL: Don Lincoln on Quark-Gluon Plasma 

    FNAL Home

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

    Matter is malleable and can change its properties with temperature. This is most familiar when comparing ice, liquid water and steam, which are all different forms of the same thing. However beyond the usual states of matter, physicists can explore other states, both much colder and hotter. In this video, Fermilab’s Dr. Don Lincoln explains the hottest known state of matter – a state that is so hot that protons and neutrons from the center of atoms can literally melt. This form of matter is called a quark gluon plasma and it is an important research topic being pursued at the LHC.

    CERN LHC MapCERN LHC Grand Tunnel
    CERN LHC particles
    LHC at CERN

    Download is available at the full article link below.

    Watch, enjoy, learn.

    See the full article here.

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

  • richardmitnick 5:35 am on March 17, 2015 Permalink | Reply
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    From New Scientist: “Quark stars: How can a supernova explode twice?” 2013 But Well Worth the Read 


    New Scientist

    09 December 2013
    Anil Ananthaswamy

    What do you get when you melt a neutron star? An unimaginably dense lump of strange matter and a whole new celestial beast

    (Image: Matt Murphy)

    ON 22 September last year, the website of The Astronomer’s Telegram alerted researchers to a supernova explosion in a spiral galaxy about 84 million light years away. There was just one problem. The same object, SN 2009ip, had blown up in a similarly spectacular fashion just weeks earlier. Such stars shouldn’t go supernova twice, let alone in quick succession. The thing was, it wasn’t the only one, the next year another supernova, SN 2010mc, did the same.

    One of the few people not to be bamboozled was Rachid Ouyed. “When I looked at those explosions, they were talking to me right away,” he says. Ouyed, an astrophysicist at the University of Calgary in Alberta, Canada, thinks that these double explosions are not the signature of a supernova, but something stranger. They may mark the violent birth of a quark star, a cosmic oddity that has only existed so far in the imaginations and equations of a few physicists. If so they would be the strongest hints yet that these celestial creatures exist in the cosmic wild.

    The implications would be enormous. These stars would take pride of place alongside the other heavenly heavyweights: neutron stars and black holes. They could help solve some puzzling mysteries related to gamma-ray bursts [GRBs] and the formation of the heftiest elements in the universe. Back on Earth, quark stars would help us better understand the fundamental building blocks of matter in ways that even machines like the Large Hadron Collider cannot.

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

    Astrophysicists can thank string theorist Edward Witten for quark stars. In 1984, he hypothesised that protons and neutrons may not be the most stable forms of matter.

    Both are made of two types of smaller entities, known as quarks: protons are comprised of two “up” quarks and one “down” quark, whereas neutrons are made of two downs and one up. Up and down are the lightest of six distinct “flavours” of quark. Add the third lightest to the mix and you get something called strange quark matter. Witten argued that this kind of matter may have lower net energy and hence be more stable than nuclear matter made of protons and neutrons.

    Quark nova

    If so, we might all start decaying into strange matter. But don’t fret. You either need to wait around longer than the age of the universe for the stuff to form spontaneously, or find somewhere with the right conditions to start the process. One place this could happen is inside neutron stars, the dense remnants of certain types of supernovae.

    When a star many times more massive than the sun runs out of fuel, its inner core implodes. The outer layers are cast off in a spectacular explosion. What’s left behind is a rapidly spinning neutron star, which as the name implies is made mainly of neutrons, with a crust of iron. Whirling up to 1000 times per second, a neutron star is constantly shedding magnetic fields. Over time, this loss of energy causes the star to spin slower and slower. As it spins down, the centrifugal forces that kept gravity at bay start weakening, allowing gravity to squish the star still further.

    In what is a blink of an eye in cosmic time, the neutrons can be converted to strange quark matter, which is a soup of up, down and strange quarks. In theory, this unusual change happens when the density inside the neutron star starts increasing. New particles called hyperons begin forming that contain at least one strange quark bound to others.

    However, the appearance of hyperons marks the beginning of the end of the neutron star. “Once you start to form hyperons, then you can start the nucleation of the first droplet of strange quark matter,” says Giuseppe Pagliara of the University of Ferrara in Italy. As the density in the core continues to increase, the star’s innards “melt”, freeing quarks from their bound state. In fact, a single droplet of strange matter is enough to trigger a runaway process that converts all the neutrons. What was a neutron star turns into a quark star.

    Of course, this assumes that Witten is correct about strange quark matter being more stable than neutrons. No one has yet proved him wrong, but it is a tough idea for some to swallow. “More conservative thinkers are just not open to the idea that free quarks exist in neutron stars,” says Fridolin Weber, an astrophysicist at the San Diego State University in California.

    Not so the daring ones. Ouyed, for instance, has been trying to convince his fellow astrophysicists of the existence of quark stars for more than a decade. Not only do these intrepid few think that quarks can exist freely inside neutron stars, they have even thought about what comes next. “We all agree that if quark stars exist, then the conversion of normal, ordinary matter into a quark star will be a very exothermic process, a lot of energy will be released,” says Pagliara. “How this energy is released is a matter of debate.”

    On one hand, Pagliara and his colleagues have done extensive simulations to show that this conversion will happen in a matter of milliseconds. In what he calls a “strong deflagration”, the neutron star burns up as it turns into a quark star. There is no explosion.

    Ouyed, on the other hand, begs to differ. His team’s simulations show that the conversion is most likely to be an extremely violent process. The seed of strange quark matter spreads until it reaches the outer crust of the neutron star. As the part of the star that has been turned into quark matter separates from the iron-rich crust, it collapses. The collapse halts when the inner core becomes incredibly dense and rebounds, creating a shock wave. Much as in a supernova, the iron-rich crust and leftover neutrons are ejected in another spectacular explosion – a “quark nova”.

    Hurtling through space, the quark nova ejecta then slam into the earlier supernova remnants, causing them to light up again, as they did after the explosion of the original, conventional star. What’s left behind is a quark star. “It was very hard to find solutions where the entire neutron star turned into a quark star, in just a puff with no explosion,” says Ouyed.

    Double explosion

    Depending on the mass of the star before its first explosion, the second blast could occur anywhere from seconds to years after the original supernova. Too soon, and the two explosions would merge, appearing as one blast, smeared out in time. Too late, and the supernova ejecta would have dispersed long before the detonation of the quark nova, and there would be no re-brightening.

    But if the timing is just right, the outcome should be observable. In 2009, Ouyed’s team predicted that if the quark nova goes off days or weeks after the supernova, there should be two peaks in energy: the first being the supernova explosion itself, and the second being the reheating of the supernova ejecta. The objects SN 2009ip and SN 2010mc matched predictions in ways almost too good to be true.

    SN 2009ip had its first major explosion in early August 2012, and 40 days later flared up again. SN 2010mc was eerily similar in its outbursts, showing a double explosion in which the peaks were about 40 days apart. While other researchers continue trying to explain these unusual observations using their tried-and-tested models of supernovae, Ouyed is convinced that we have witnessed quark stars being born.

    Oddly, it is the first peak in both events that convinces him. If these have all the characteristics of a regular supernova, it makes the second boom harder to explain using conventional arguments. “When you look at the first ejecta, it looks like a duck and walks like a duck: it’s a supernova,” says Ouyed. “Then what’s the second one?”

    He points the finger at quark novae. “We just applied our model of the dual shock quark nova, and it was actually easy to fit,” he says. “That’s the beauty of it.”

    While Pagliara and Ouyed’s teams disagree on whether the transition from a neutron star to a quark star is explosive, they do agree that space should be littered with quark stars. How should we look for them?

    We might be mistaking some of them for neutron stars, says Pagliara. Most neutron stars weigh as much as 1.4 suns or slightly more. The best studied examples, orbiting each other in systems called Hulse-Taylor binary pulsars, certainly follow this pattern. Both neutron stars involved weigh in at 1.4 solar masses. However, Pagliara is bothered by two discoveries of neutron stars that tip the scales at 2 solar masses each. “It’s difficult to reach this mass with normal particle components like neutrons, protons and hyperons,” he says.

    This has to do with a property of matter called its equation of state. Equations of state describe how matter behaves under changes in physical conditions, such as pressure and temperature. Hyperons, which are precursors to strange quark matter, have a “soft” equation of state. Their existence in the dense core of a neutron star makes the star more compressible, causing it to shrink in size.

    Astronomers estimate that neutron stars are about 10 kilometres across – but squeezing 2 solar masses into an object of such size would end up creating a black hole. Pagliara says that compact stars weighing 2 solar masses or more have to be bigger, or put another way, the matter has to be “stiffer” so that gravity cannot compress it as much. There is one candidate with a stiffer equation of state: strange quark matter.

    Pagliara and his colleague Alessandro Drago and others claim that the compact stars we have spotted come from two families. The smaller ones must be the run-of-the-mill neutron stars. The larger ones must be quark stars. The only way to verify this claim is to measure their masses and also measure their radii to the nearest kilometre. A proposed European satellite mission called the Large Observatory for X-ray Timing could do just that. Its aim is to measure the equation of state for compact objects – and thus differentiate between neutron stars and quark stars.


    Meanwhile, Ouyed’s team is concentrating on predictions based on their quark nova model. One prediction has to do with the creation of heavy elements in the universe. Once a massive star goes supernova, weighty elements are synthesised in a matter of milliseconds, when neutrons are absorbed into iron nuclei. These neutron-rich nuclei are unstable and decay into elements further up in the periodic table when neutrons get converted to protons. “But the challenge with supernovae has always been to go to really heavy elements,” says Ouyed. The iron and neutrons needed for the process are in short supply because most of them are left behind in the remnant neutron star.

    The quark nova solves that problem. Its ejecta are a potent mix of neutrons and iron from the neutron star’s crust, providing just the laboratory for synthesising the heaviest elements. Ouyed is urging astronomers to study double explosions carefully. His team predicts that the second blast should show the presence of elements heavier than atomic mass 130, elements which should be missing from the first explosion.

    The conversion of a neutron star to a quark star could also solve another problem plaguing astrophysics: the source of some long-duration gamma-ray bursts, which are among the brightest events in the universe. On 9 July 2011, NASA’s SWIFT gamma-ray satellite saw a burst with two spectacular peaks of emission, spaced 11 minutes apart.

    NASA SWIFT Telescope

    And the second was the stronger of the two. The traditional “collapsar” model of gamma-ray bursts relies on a star collapsing to a black hole. As the last remnants of the doomed star fall in, it is thought to result in such an emission. But 11 minutes is an eternity for a black hole – it’s hard to make sense of the second peak.

    Pagliara thinks his team has the answer. According to their model, a neutron star converts to a quark star without an explosion. Yet there is still a tremendous release of energy, which Pagliara suspects goes into gamma rays. This could explain the second peak. “At the moment, and it’s speculation, we think that this second event could be related to quark stars,” he says. “If you want to see a possible signature of formation of quark matter, you should probably look at those gamma-ray bursts that have an activity long after the main event.”

    Quark world

    Confirming the existence of quark stars and verifying their properties could have a huge impact on particle physics. Colliders like the LHC and the Relativistic Heavy Ion Collider (RHIC) in Brookhaven National Laboratory [BNL]in New York have been smashing heavy ions head-on to create a state of matter called a quark-gluon plasma, where quarks are essentially free.

    BNL RHIC Campus
    RHIC at BNL

    The best way to study this phase of matter is using a method called lattice quantum chromodynamics [QCD]. But physicists have only been able to solve the equations of lattice QCD for high temperatures and low density – the conditions created at the LHC and the RHIC. The equations are intractable for other conditions. For instance, it is impossible to calculate the density at which protons and neutrons can melt into their constituent quarks at low temperatures.

    Enter quark stars. First, if their existence is confirmed, it proves that quarks can exist freely at high densities and low temperatures, rather than bound up in hadrons – the catch-all name given to any particle made of quarks. Second, for the explosive quark nova model Ouyed’s team has shown that the density at which quarks get freed is intimately linked to the time lag between the supernova and the quark nova. Measure the timing of the double explosion and you will glean important clues about conditions at the transition. “The quark nova is a very beautiful bridge that straddles the hadronic world and the quark world,” says Ouyed. “It’d be a very nice tool to use for physics and astrophysics.”

    Weber agrees that quark stars, if they exist, would be a unique astrophysical laboratory. They would help us probe properties of matter in ways that we cannot do with the best colliders on Earth – in the domain of high densities and low temperatures. “This is a regime that is only accessible to stars, and only stars can tell us what will happen.”

    See the full article here.

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  • richardmitnick 9:02 pm on January 8, 2015 Permalink | Reply
    Tags: , , Quark-gluon plasma   

    From Perimeter: “A simpler way to understand ultra-hot chaos” 

    Perimeter Institute
    Perimeter Institute

    January 8, 2015
    Tenille Bonoguore

    Perimeter researcher Michal P. Heller has created a shortcut to understand primordial matter in its most extreme state.

    To recreate the birth of the universe, most physicists believe that you would first need a big bang. This would be followed almost instantly by the appearance of an ultra-hot blob of plasma, the primordial soup that formed the basis of everything in existence.

    Quark-gluon plasma

    It’s not exactly a process that is easily replicated, but in heavy-ion colliders, experimentalists are creating “little bangs” to produce tiny droplets of quark-gluon plasma (QGP).

    The experiments offer a glimpse of the kind of matter that filled the early universe, but there’s a problem. In its earliest stages – between “bang” and “goop” – the system is in extreme distortion. In fact, it’s not until the system cools down that it reaches equilibrium and can be assessed.

    It is this period of ultra-hot chaos that intrigues Perimeter Institute postdoctoral researcher Michal P. Heller. And in a new paper published recently in Physical Review Letters, he has brought together two seemingly different fields of study – hydrodynamics and string theory – to help describe it.

    In ordinary matter, quarks do not exist in isolation; they are always bound extremely tightly by gluons in atomic nuclei. But in extreme conditions – say, in temperatures a million times hotter than the sun – these bonds can “melt,” forming an ultra-hot, almost-frictionless plasma in which quarks and gluons move freely.

    QGP has recently been created by smashing atomic nuclei against each other at the Relativistic Heavy-Ion Collider at the Brookhaven National Laboratory in the United States, and at the Large Hadron Collider at CERN in Switzerland.

    BNL RHIC Campus
    RHIC at BNL

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

    The tiny droplets produced by these “little bangs” exist for brief flashes of time, like super-hot fireballs that quickly expand and cool into ordinary matter. In the moment after the collision, the ultra-hot system is in extreme distortion, existing at the threshold of being called a fluid.

    Despite the fact that theorists know the microscopic rules that govern such ultra-energetic collisions, questions still abound. It is clear these systems only become plasma once they settle enough to reach equilibrium. Working out what happens in the chaotic interim, before the system equilibrates, requires extremely complex computations.

    The standard modelling for plasma experiments uses relativistic hydrodynamics, a theory similar to that describing the motion of water but which also incorporates [Albert] Einstein’s special relativity. (This is because QGP and its microscopic constituents move with large velocities, at which relativistic effects become important.)

    Some researchers, including Heller, have simplified the problem by equating the relaxation of the QGP “fireball” to a black hole reaching equilibrium in a hypothetical five-dimensional space. This approach takes methods derived from string theory, and applies them to the physics of the “little bang” experiments and the droplets of QGP they create.

    Now, Heller and his co-authors have put forward a computational technique that is something of a further short-cut for theorists: instead of doing the calculations using five-dimensional Einstein equations – which is very complicated – they have developed a way to incorporate part of those calculations into a four-dimensional description that is coupled to conventional hydrodynamics equations.

    “The paper shows something about the theories of relativistic hydrodynamics that was known, but not many people had thought about it seriously,” Heller says. “Our observation opens up a new possibility of describing transient relaxation effects governing the approach to the quark-gluon plasma phase.”

    This work is a return of sorts for Heller, a Polish scientist who came to Perimeter in 2014 from the University of Amsterdam. His research career began with a 2007 paper studying theories of second-order relativistic hydrodynamics, which factors causal evolution into standard fluid dynamics. In 2012 and 2013, his work in string theory and strong gravity brought him back to those theories, but with a new perspective.

    “What’s been fun is coming back to the project I started my research career with, and realizing that the things which I thought several years ago were simple are actually not so trivial and have far-reaching consequences,” he says.

    When he was younger, he thought the universe could be understood through one simple model. Now, he sees much more nuance: “At some point, you start appreciating that everything is complex and interconnected.”

    QGP is like that, too, he says. While researchers would probably like to create QGP in a simple state of equilibrium (so that they can introduce their own distortions and measure the effects), reality is much more complex. Current experimental and theoretical approaches aren’t sensitive enough to capture and analyze in detail the droplets’ initial, highly distorted state, but Heller’s paper is a step in this direction.

    “Is that a choice? It’s more of a necessity, at least given what we have available here on Earth,” he says.

    Should other researchers build on this work, combining it with complementary approaches of initial state physics to construct some sort of a hybrid, he says these generalized theories of hydrodynamics “will be a crucial ingredient of whatever comes next.”

    See the full article here.

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    About Perimeter

    Perimeter Institute is a leading centre for scientific research, training and educational outreach in foundational theoretical physics. Founded in 1999 in Waterloo, Ontario, Canada, its mission is to advance our understanding of the universe at the most fundamental level, stimulating the breakthroughs that could transform our future. Perimeter also trains the next generation of physicists through innovative programs, and shares the excitement and wonder of science with students, teachers and the general public.

  • richardmitnick 3:12 pm on October 10, 2014 Permalink | Reply
    Tags: , Quark-gluon plasma,   

    From Science Friday via BNL: "How to Make Quark Soup" 

    Brookhaven Lab


    Watch, enjoy, learn

    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.

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  • richardmitnick 8:21 pm on October 2, 2014 Permalink | Reply
    Tags: , , , , , , Quark-gluon plasma   

    From LBL: “A Closer Look at the Perfect Fluid” 

    Berkeley Logo

    Berkeley Lab

    October 2, 2014
    Kate Greene 510-486-4404

    Researchers at Berkeley Lab and their collaborators have honed a way to probe the quark-gluon plasma, the kind of matter that dominated the universe immediately after the big bang.

    A simulated collision of lead ions, courtesy the ALICE experiment at CERN. – See more at: http://newscenter.lbl.gov/2014/10/02/a-closer-look-at-the-perfect-fluid/#sthash.LuD3V5BH.dpuf

    By combining data from two high-energy accelerators, nuclear scientists have refined the measurement of a remarkable property of exotic matter known as quark-gluon plasma. The findings reveal new aspects of the ultra-hot, “perfect fluid” that give clues to the state of the young universe just microseconds after the big bang.

    The multi-institutional team known as the JET Collaboration, led by researchers at the U.S. Department of Energy’s Lawrence Berkeley National Lab (Berkeley Lab), published their results in a recent issue of Physical Review C. The JET Collaboration is one of the Topical Collaborations in nuclear theory established by the DOE Office of Science in 2010. JET, which stands for Quantitative Jet and Electromagnetic Tomography, aims to study the probes used to investigate high-energy, heavy-ion collisions. The Collaboration currently has 12 participating institutions with Berkeley Lab as the leading institute.

    “We have made, by far, the most precise extraction to date of a key property of the quark-gluon plasma, which reveals the microscopic structure of this almost perfect liquid,” says Xin-Nian Wang, physicist in the Nuclear Science Division at Berkeley Lab and managing principal investigator of the JET Collaboration. Perfect liquids, Wang explains, have the lowest viscosity-to-density ratio allowed by quantum mechanics, which means they essentially flow without friction.

    Hot Plasma Soup

    To create and study the quark-gluon plasma, nuclear scientists used particle accelerators called the Relativistic Heavy-ion Collider (RHIC) at the Brookhaven National Laboratory in New York and the Large Hadron Collider (LHC) at CERN in Switzerland. By accelerating heavy atomic nuclei to high energies and blasting them into each other, scientists are able to recreate the hot temperature conditions of the early universe.

    BNL RHIC Campus
    BNL RHIC schematic
    RHIC at BNL

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

    Inside protons and neutrons that make up the colliding atomic nuclei are elementary particles called quarks, which are bound together tightly by other elementary particles called gluons. Only under extreme conditions, such as collisions in which temperatures exceed by a million times those at the center of the sun, do quarks and gluons pull apart to become the ultra-hot, frictionless perfect fluid known as quark-gluon plasma.

    “The temperature is so high that the boundaries between different nuclei disappear so everything becomes a hot-plasma soup of quarks and gluons,” says Wang. This ultra-hot soup is contained within a chamber in the particle accelerator, but it is short-lived—quickly cooling and expanding—making it a challenge to measure. Experimentalists have developed sophisticated tools to overcome the challenge, but translating experimental observations into precise quantitative understanding of the quark-gluon plasma has been difficult to achieve until now, he says.

    Looking Inside

    In this new work, Wang’s team refined a probe that makes use of a phenomenon researchers at Berkeley Lab first theoretically outlined 20 years ago: energy loss of a high-energy particle, called a jet, inside the quark gluon plasma.

    “When a hot quark-gluon plasma is generated, sometimes you also produce these very energetic particles with an energy a thousand times larger than that of the rest of the matter,” says Wang. This jet propagates through the plasma, scatters, and loses energy on its way out.

    Since the researchers know the energy of the jet when it is produced, and can measure its energy coming out, they can calculate its energy loss, which provides clues to the density of the plasma and the strength of its interaction with the jet. “It’s like an x-ray going through a body so you can see inside,” says Wang.

    Xin Nian Wang, physicist in the Nuclear Science Division at Berkeley Lab and managing principal investigator of the JET Collaboration.

    One difficulty in using a jet as an x-ray of the quark-gluon plasma is the fact that a quark-gluon plasma is a rapidly expanding ball of fire—it doesn’t sit still. “You create this hot fireball that expands very fast as it cools down quickly to ordinary matter,” Wang says. So it’s important to develop a model to accurately describe the expansion of plasma, he says. The model must rely on a branch of theory called relativistic hydrodynamics in which the motion of fluids is described by equations from Einstein’s theory of special relativity.

    Over the past few years, researchers from the JET Collaboration have developed such a model that can describe the process of expansion and the observed phenomena of an ultra-hot perfect fluid. “This allows us to understand how a jet propagates through this dynamic fireball,” says Wang

    Employing this model for the quark-gluon plasma expansion and jet propagation, the researchers analyzed combined data from the PHENIX and STAR experiments at RHIC and the ALICE and CMS experiments at LHC since each accelerator created quark-gluon plasma at different initial temperatures. The team determined one particular property of the quark-gluon plasma, called the jet transport coefficient, which characterizes the strength of interaction between the jet and the ultra-hot matter. “The determined values of the jet transport coefficient can help to shed light on why the ultra-hot matter is the most ideal liquid the universe has ever seen,” Wang says.

    BNL Phenix

    BNL Star
    STAR at BNL


    CERN CMS New
    CMS at CERN

    Peter Jacobs, head of the experimental group at Berkeley Lab that carried out the first jet and flow measurements with the STAR Collaboration at RHIC, says the new result is “very valuable as a window into the precise nature of the quark gluon plasma. The approach taken by the JET Collaboration to achieve it, by combining efforts of several groups of theorists and experimentalists, shows how to make other precise measurements of properties of the quark gluon plasma in the future.”

    The team’s next steps are to analyze future data at lower RHIC energies and higher LHC energies to see how these temperatures might affect the plasma’s behavior, especially near the phase transition between ordinary matter and the exotic matter of the quark-gluon plasma.

    This work was supported by the DOE Office of Science, Office of Nuclear Physics and used the facilities of the National Energy Research Scientific Computing Center (NERSC) located at Berkeley Lab.

    See the full article here.

    A U.S. Department of Energy National Laboratory Operated by the University of California

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  • richardmitnick 4:33 pm on August 25, 2014 Permalink | Reply
    Tags: , , , , Quark-gluon plasma,   

    From Livermore Lab: “Calculating conditions at the birth of the universe” 

    Lawrence Livermore National Laboratory

    Anne M Stark, LLNL, (925) 422-9799, stark8@llnl.gov

    Using a calculation originally proposed seven years ago to be performed on a petaflop computer, Lawrence Livermore researchers computed conditions that simulate the birth of the universe.

    When the universe was less than one microsecond old and more than one trillion degrees, it transformed from a plasma of quarks and gluons into bound states of quarks – also known as protons and neutrons, the fundamental building blocks of ordinary matter that make up most of the visible universe.

    The theory of quantum chromodynamics (QCD) governs the interactions of the strong nuclear force and predicts it should happen when such conditions occur.

    In a paper appearing in the Aug. 18 edition of Physical Review Letters, Lawrence Livermore scientists Chris Schroeder, Ron Soltz and Pavlos Vranas calculated the properties of the QCD phase transition using LLNL’s Vulcan, a five-petaflop machine. This work was done within the LLNL-led HotQCD Collaboration, involving Los Alamos National Laboratory, Institute for Nuclear Theory, Columbia University, Central China Normal University, Brookhaven National Laboratory and Universität Bielefed in Germany.

    A five Petaflop IBM Blue Gene/Q supercomputer named Vulcan

    This is the first time that this calculation has been performed in a way that preserves a certain fundamental symmetry of the QCD, in which the right and left-handed quarks (scientists call this chirality) can be interchanged without altering the equations. These important symmetries are easy to describe, but they are computationally very challenging to implement.

    “But with the invention of petaflop computing, we were able to calculate the properties with a theory proposed years ago when petaflop-scale computers weren’t even around yet,” Soltz said.

    The research has implications for our understanding of the evolution of the universe during the first microsecond after the Big Bang, when the universe expanded and cooled to a temperature below 10 trillion degrees.

    Below this temperature, quarks and gluons are confined, existing only in hadronic bound states such as the familiar proton and neutron. Above this temperature, these bound states cease to exist and quarks and gluons instead form plasma, which is strongly coupled near the transition and coupled more and more weakly as the temperature increases.

    “The result provides an important validation of our understanding of the strong interaction at high temperatures, and aids us in our interpretation of data collected at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory and the Large Hadron Collider at CERN.” Soltz said.

    Brookhaven RHIC
    RHIC at Brookhaven

    CERN LHC Grand Tunnel
    LHC at CERN

    Soltz and Pavlos Vranas, along with former colleague Thomas Luu, wrote an essay predicting that if there were powerful enough computers, the QCD phase transition could be calculated. The essay was published in Computing in Science & Engineering in 2007, “back when a petaflop really did seem like a lot of computing,” Soltz said. “With the invention of petaflop computers, the calculation took us several months to complete, but the 2007 estimate turned out to be pretty close.”

    The extremely computationally intensive calculation was made possible through a Grand Challenge allocation of time on the Vulcan Blue Gene/Q Supercomputer at Lawrence Livermore National Laboratory.

    See the full article here.

    Operated by Lawrence Livermore National Security, LLC, for the Department of Energy’s National Nuclear Security
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  • richardmitnick 2:33 pm on December 6, 2013 Permalink | Reply
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    From Brookhaven Lab: “Tiny Drops of Hot Quark Soup—How Small Can They Be?” 

    Brookhaven Lab

    New analyses of deuteron-gold collisions at RHIC reveal that even small particles can create big surprises

    December 6, 2013
    Karen McNulty Walsh

    Scientists designed and built the Relativistic Heavy Ion Collider (RHIC) at the U.S. Department of Energy’s Brookhaven National Laboratory to create and study a form of matter that last existed a fraction of a second after the Big Bang, some 13.8 billion years ago. The early-universe matter is created when two beams of gold nuclei traveling close to the speed of light slam into one another. The high-speed particle smashups pack so much energy into such a tiny space that the hundreds of protons and neutrons making up the nuclei “melt” and release their constituent particles—quarks and gluons—so scientists can study these building blocks of matter as they existed at the dawn of time.

    Components of the PHENIX detector at Brookhaven’s Relativistic Heavy Ion Collider (RHIC). PHENIX weighs 4,000 tons. It has large steel magnets and a dozen detector sub-systems that bend and track a wide range of particles while measuring their properties (e.g., momentum and energy) as they emerge from collisions. No image credit.

    Collisions between gold nuclei and deuterons—much smaller particles made of just one proton and one neutron—weren’t supposed to create this superhot subatomic soup known as quark-gluon plasma (QGP). They were designed as a control experiment, to generate data to compare against RHIC’s gold-gold smashups. But new analyses indicate that these smaller particle impacts may be serving up miniscule drops of hot QGP—a finding consistent with similar results from Europe’s Large Hadron Collider (LHC), which can also collide heavy nuclei.

    “Considering that the quark-gluon plasma we create in gold-gold collisions at RHIC fills a space that is approximately the size of the nucleus of a single gold atom, the possible hot spots we’re talking about in these deuteron-gold collisions are much, much smaller—and an intriguing surprise,” said Dave Morrison, a physicist at Brookhaven and co-spokesperson for RHIC’s PHENIX collaboration. The collaboration describes their results in two papers just published by Physical Review Letters, one of which is highlighted by the journal.

    The findings at RHIC and the LHC have triggered active debate about their interpretation. Said PHENIX co-spokesperson Jamie Nagle of the University of Colorado, “There isn’t yet universal agreement about what we’re seeing in these small systems, but if indeed nearly perfect fluid droplets of quark-gluon plasma are being formed, this may be a perfect testing ground for understanding the essential conditions for creating this remarkable state of matter.”

    See the full article here.

    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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