Manufacturing Bits: Feb. 14

Making quark soup
CERN, the European Organization for Nuclear Research, recently presented its latest results on quark-gluon plasma, or quark soup, a state of matter that supposedly existed during the early formation of the universe.

For this, CERN used the Large Hadron Collider (LHC), the world’s most powerful particle accelerator. The LHC is situated in a tunnel 100 meters underground on the Franco-Swiss border near Geneva, Switzerland.

Researchers recreated conditions similar to those just after the big bang. In the LHC, it created collisions with lead nuclei, generating temperatures more than 100,000 times hotter than the center of the sun.

As a result, protons and neutrons that make up the lead ions melted, thereby freeing quarks from their bonds with gluons. This, in turn, allowed researchers to study quark-gluon plasma or quark soup. Quarks and gluons are sub-atomic particles, which are among the basic building blocks of matter.

Heavy ions (Source: CERN)

Many believe the universe was in a quark–gluon plasma state during a few milliseconds after the big bang. Studying quark-gluon plasma can help explain the particles that make up the universe and matter.

In the experiment at CERN, the ion collisions create only a small droplet of quark-gluon plasma. Researchers found that “heavy quarks directly ‘feel’ the shape and size of the quark-gluon-plasma droplet created within the region of the collision,” according to CERN. “This means that even the heaviest quarks move with the plasma, which is primarily formed of light quarks and gluons.”

The findings will help with the understanding of Quantum Chromodynamics (QCD). This is the force that describes the interactions between quarks and gluons. “Quark matter demonstrates the wealth of physics results on a topic, which is inherently very complex, heavy ion physics,” said Eckhard Elsen, director for research and computing at CERN. “With the LHC performing so well and in so many different beam constellations, we have the experimental tools at hand to shed light on the state of matter that dominated in the early beginning of our universe.”

Developing stable helium
The Skolkovo Institute of Science and Technology, the Moscow Institute of Physics and Technology and Stony Brook University have produced a stable helium compound.

Helium, the second most abundant element in the universe after hydrogen, is typically inert and doesn’t easily form compounds with other elements. Helium has no known stable compounds, according to the Deutsches Elektronen-Synchrotron (DESY), a research center of the Helmholtz Association.

To search for stable helium compounds, researchers used a crystal structure predicting tool. The tool, dubbed USPEX, uncovered two candidates. One was Na2He, a compound of sodium (Na) and helium (He). The other was Na2HeO, which also contains oxygen (O).

First, researchers synthesized a Na2He compound. This was done using a diamond anvil cell that produced the compound at pressures of about 1.1 million times Earth’s atmospheric pressure. Evidence of the compound was found using X-ray diffraction experiments at DESY. The experiments were conducted at DESY’s X-ray source, dubbed PETRA III.

Crystal structure of Na2He. (Credit: Artem R. Oganov/Skoltech)

The second compound, Na2HeO, is predicted to be stable in the pressure range from 0.15 to 1.1 million atmospheres, according to DESY. “The compound that we discovered is very peculiar: helium atoms do not actually form any chemical bonds, yet their presence fundamentally changes chemical interactions between sodium atoms, forces electrons to localize inside cubic voids of the structure and makes this material insulating,” said Xiao Dong, a researcher.

The second compound, Na2HeO, is predicted to be stable in the pressure range from 0.15 to 1.1 million atmospheres, according to DESY. “This study shows how new surprising phenomena can be discovered by combination of powerful theoretical methods and state-of-the-art experiments,” said Artem Oganov, at researcher at the Skolkovo Institute of Science and Technology.

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