Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

'Perfect' Liquid Hot Enough to be Quark Soup

04.03.2010
Protons, neutrons melt to produce ‘quark-gluon plasma’ at RHIC

Recent analyses from the Relativistic Heavy Ion Collider (RHIC), a 2.4-mile-circumference “atom smasher” at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory, establish that collisions of gold ions traveling at nearly the speed of light have created matter at a temperature of about 4 trillion degrees Celsius — the hottest temperature ever reached in a laboratory, about 250,000* times hotter than the center of the Sun. This temperature, based upon measurements by the PHENIX collaboration at RHIC, is higher than the temperature needed to melt protons and neutrons into a plasma of quarks and gluons. Details of the findings will be published in Physical Review Letters.

These new temperature measurements, combined with other observations analyzed over nine years of operations by RHIC’s four experimental collaborations — BRAHMS, PHENIX, PHOBOS, and STAR — indicate that RHIC’s gold-gold collisions produce a freely flowing liquid composed of quarks and gluons. Such a substance, often referred to as quark-gluon plasma, or QGP, filled the universe a few microseconds after it came into existence 13.7 billion years ago. At RHIC, this liquid appears, and the quoted temperature is reached, in less time than it takes light to travel across a single proton.

“This research offers significant insight into the fundamental structure of matter and the early universe, highlighting the merits of long-term investment in large-scale, basic research programs at our national laboratories,” said Dr. William F. Brinkman, Director of the DOE Office of Science. “I commend the careful approach RHIC scientists have used to gather detailed evidence for their claim of creating a truly remarkable new form of matter.”

According to Steven Vigdor, Brookhaven’s Associate Laboratory Director for Nuclear and Particle Physics, who oversees the RHIC research program, “These data provide the first measurement of the temperature of the quark-gluon plasma at RHIC.”

Scientists measure the temperature of hot matter by looking at the color, or energy distribution, of light emitted from it — similar to the way one can tell that an iron rod is hot by looking at its glow. Because light interacts very little with the hot liquid produced at RHIC, it bears accurate witness to the early cauldron-like conditions created within.

Said Vigdor, “The temperature inferred from these new measurements at RHIC is considerably higher than the long-established maximum possible temperature attainable without the liberation of quarks and gluons from their normal confinement inside individual protons and neutrons.

“However,” he added, “the quarks and gluons in the matter we see at RHIC behave much more cooperatively than the independent particles initially predicted for QGP.”

Hot gas vs. hot liquid

Scientists believe that a plasma of quarks and gluons existed a few microseconds after the birth of the universe, before cooling and condensing to form the protons and neutrons that make up all the matter around us — from individual atoms to stars, planets, and people. Although the matter produced at RHIC survives for much less than a billionth of a trillionth of a second, its properties can be determined using RHIC’s highly sophisticated detectors to look at the thousands of particles emitted during its brief lifetime. The measurements provide new insights into Nature’s strongest force — in essence, what holds all the protons and neutrons of the universe together.

Predictions made prior to RHIC’s initial operations in 2000 expected that the quark-gluon plasma would exist as a gas. But surprising and definitive data from RHIC’s first three years of operation, presented by RHIC scientists in April 2005, showed that the matter produced at RHIC behaves as a liquid, whose constituent particles interact very strongly among themselves. This liquid matter has been described as nearly “perfect” in the sense that it flows with almost no frictional resistance, or viscosity. Such a “perfect” liquid doesn’t fit with the picture of “free” quarks and gluons physicists had previously used to describe QGP.

In the papers published in 2005, RHIC physicists laid out a plan of crucial measurements to clarify the nature and constituents of the “perfect” liquid. Measuring the temperature early in the collisions was one of those goals. Models of the evolution of the matter produced in RHIC collisions had suggested that the initial temperature might be high enough to melt protons, but a more direct measurement of the temperature required detecting photons — particles of light — emitted near the beginning of the collision, which travel outward undisturbed by their surroundings.

“This was an extraordinarily challenging measurement,” explained Barbara Jacak, a professor of physics at Stony Brook University and spokesperson for the PHENIX collaboration. “There are many ways that photons can be produced in these violent collisions. We were able to ‘eliminate’ the contribution from these other sources by exploiting RHIC’s flexibility to measure them directly and to make the same measurement in collisions of protons, rather than of gold nuclei. Thus we could pin down excess production in the gold-gold collisions, and determine the temperature of the matter that radiated the excess photons. By matching theoretical models of the expanding plasma to the data, we can determine that the initial temperature of the ‘perfect’ liquid has reached about four trillion degrees Celsius.”

Moving forward

The discoveries at RHIC have led to compelling new questions in the field of quantum chromodynamics (QCD), the theory that describes the interactions of the smallest known components of the atomic nucleus. To probe these and other questions and conduct detailed studies of the plasma, Brookhaven physicists are planning to upgrade RHIC over the next few years to increase its collision rate and detector capabilities.

“These technical improvements will facilitate studies of rare signals providing measurements of even better precision on temperature, viscosity, and other basic properties of the nearly perfect liquid quark-gluon plasma created at RHIC,” Vigdor said.

Research at RHIC is funded primarily by the U.S. Department of Energy's Office of Science and by various national and international collaborating institutions.

*corrected calculation

RHIC and the LHC

The research program at RHIC will be complemented by studies soon to get underway at the Large Hadron Collider (LHC), a 17-mile-circumference particle accelerator beginning operations in Europe. The LHC will devote a month each year to colliding heavy nuclei at energies much higher than RHIC’s — extending the exploration of matter one step farther back in time toward the birth of the universe. Calculations of quantum chromodynamics now predict that as temperatures increase significantly, quark-gluon matter should slowly evolve from RHIC’s perfect liquid to an ideal gas. The LHC will provide the first opportunity to observe this evolution as collision temperatures increase by a factor of 2 to 3 in its own heavy-ion experiments, set to begin in late 2010.

At the same time, RHIC’s upgrades and flexible operations will allow scientists to quantify particle interactions inside the perfect liquid and explore the phase diagram of nuclear matter. “RHIC and the LHC will work together in complementary ways to broaden our understanding of the basic constituents of our universe and the forces that shape them,” Vigdor said.

Saeko Okada | Research asia research news
Further information:
http://www.bnl.gov/bnlweb/pubaf/pr/PR_display.asp?prID=1074
http://www.researchsea.com

More articles from Physics and Astronomy:

nachricht MSU astronomers discovered supermassive black hole in an ultracompact dwarf galaxy
14.08.2018 | Lomonosov Moscow State University

nachricht ASU astrophysicist helps discover that ultrahot planets have starlike atmospheres
13.08.2018 | Arizona State University

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

Im Focus: Lining up surprising behaviors of superconductor with one of the world's strongest magnets

Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur

What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...

Im Focus: World record: Fastest 3-D tomographic images at BESSY II

The quality of materials often depends on the manufacturing process. In casting and welding, for example, the rate at which melts solidify and the resulting microstructure of the alloy is important. With metallic foams as well, it depends on exactly how the foaming process takes place. To understand these processes fully requires fast sensing capability. The fastest 3D tomographic images to date have now been achieved at the BESSY II X-ray source operated by the Helmholtz-Zentrum Berlin.

Dr. Francisco Garcia-Moreno and his team have designed a turntable that rotates ultra-stably about its axis at a constant rotational speed. This really depends...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

2018 Work Research Conference

25.07.2018 | Event News

 
Latest News

'Building up' stretchable electronics to be as multipurpose as your smartphone

14.08.2018 | Information Technology

During HIV infection, antibody can block B cells from fighting pathogens

14.08.2018 | Life Sciences

First study on physical properties of giant cancer cells may inform new treatments

14.08.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>