Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Tiny Drops of Early Universe 'Perfect' Fluid

02.09.2015

First results from collisions of three-particle ions with gold nuclei reveal clear-cut evidence of primordial soup's signature particle flow

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.


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.


Relativistic Heavy Ion Collider's PHENIX detector

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). 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

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 the agencies and organizations listed here: https://www.bnl.gov/rhic/funding.asp.

***
SIDEBAR: RHIC's Versatility, Productivity Key to Discovery

The versatility and productivity of RHIC as a collider were essential to all these experiments. The collisions of helium-3 with gold in 2014 were conducted almost as a bonus part of that run, Nagle explained.

"The collider's luminosity, or collision rate, was so high earlier in the run that we had collected almost 40 percent more data than we'd set as our goal a few weeks before the run was over," Nagle said. "That gave us the opportunity to do these tests for the remaining weeks."

RHIC's ability to collide a wide variety of ions, and easily switch the ion species fed into the accelerator, were also essential to this success. This versatility stems from innovative accelerator components, including the Electron Beam Ion Source and the Laser Ion Source.

Finally, thanks to a new configuration of certain magnets that make up the 2.4-mile-circumference RHIC accelerator, protons collided with gold nuclei for the first time during the 2015 run. Results from those collisions are in the very early stages of analysis.

"Thanks to these capabilities, 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. "This is the way to do good basic science-change just one thing at a time, the number of particles in the ion smashing into the gold nucleus, to test for these interesting geometrical effects."

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.

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. Brookhaven is operated and managed for DOE's Office of Science by Brookhaven Science Associates, a limited-liability company founded by the Research Foundation for the State University of New York on behalf of Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit applied science and technology organization.

An electronic version of this news release with related graphics is posted online:
http://www.bnl.gov/newsroom/news.php?a=11749

Media contacts: Karen McNulty Walsh, (631) 344-8350, kmcnulty@bnl.gov, or Peter Genzer, (631) 344-3174, genzer@bnl.gov

Contact Information
Karen McNulty Walsh
Principal Media & Communications Specialist
kmcnulty@bnl.gov
Phone: 631-344-8350

Karen McNulty Walsh | newswise

Further reports about: Fluid Laboratory PHENIX Universe collisions droplets nuclei quark-gluon plasma

More articles from Physics and Astronomy:

nachricht NASA's Fermi catches gamma-ray flashes from tropical storms
25.04.2017 | NASA/Goddard Space Flight Center

nachricht DGIST develops 20 times faster biosensor
24.04.2017 | DGIST (Daegu Gyeongbuk Institute of Science and Technology)

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: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

NASA examines newly formed Tropical Depression 3W in 3-D

26.04.2017 | Earth Sciences

New High-Performance Center Translational Medical Engineering

26.04.2017 | Health and Medicine

NASA's Fermi catches gamma-ray flashes from tropical storms

25.04.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>