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Category: particle physics – Page 100

Tuning magnetism with voltage opens a new path to spintronic neuromorphic circuits

A team of researchers has discovered a new way to control the magnetic behavior of quantum materials using applied voltages. Specifically, the material lanthanum strontium manganite (LSMO), which is magnetic and metallic at low temperatures but non-magnetic and insulating when relatively warm, can be influenced by voltage.

The work is published in the journal Nano Letters.

Quantum materials like LSMO are materials that possess special properties because of the rules of quantum mechanics. Researchers discovered that applying voltage to LSMO in its magnetic phase causes the material to split into regions with distinct magnetic properties. The magnetic properties of these regions depend on the applied voltage. This is important because normally, don’t respond to voltage.

ALICE finds first ever evidence of the antimatter partner of hyperhelium-4

CERN discovers antihyperhelium-4, the heaviest antimatter particle to date.

Scientists at CERN’s Large Hadron Collider have discovered the heaviest antimatter particle ever observed: antihyperhelium-4.

This exotic particle, the antimatter counterpart of hyperhelium-4, contains two antiprotons, an antineutron, and an antilambda particle. The breakthrough offers insights into the extreme conditions of the early universe and sheds light on the baryon asymmetry problem — why our universe is dominated by matter despite matter and antimatter being created in equal amounts during the Big Bang.

The discovery was made using lead-ion collisions at the LHC, recreating the hyper-hot environment of the newborn universe. Machine learning models analyzed the data, identifying antihyperhelium-4 particles and precisely measuring their masses.

While the experiment confirmed that matter and antimatter are created in equal portions, the mystery of what tipped the cosmic balance remains unsolved. With ongoing upgrades to the LHC, more groundbreaking discoveries in antimatter research could be on the horizon.

Illustration of the production of antihyperhelium-4 (a bound state of two antiprotons, an antineutron and an antilambda) in lead–lead collisions. (Image: J. Ditzel with AI-assistance) Collisions between heavy ions at the Large Hadron Collider (LHC) create quark–gluon plasma, a hot and dense state of matter that is thought to have filled the Universe around one millionth of a second after the Big Bang. Heavy-ion collisions also create suitable conditions for the production of atomic nuclei and exotic hypernuclei, as well as their antimatter counterparts, antinuclei and antihypernuclei. Measurements of these forms of matter are important for various purposes, including helping to understand the formation of hadrons from the plasma’s constituent quarks and gluons and the matter–antimatter asymmetry seen in the present-day Universe.

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Fresh, direct evidence for tiny drops of quark-gluon plasma

A new analysis of data from the PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC) reveals fresh evidence that collisions of even very small nuclei with large ones might create tiny specks of a quark-gluon plasma (QGP). Scientists believe such a substance of free quarks and gluons, the building blocks of protons and neutrons, permeated the universe a fraction of a second after the Big Bang.

RHIC’s energetic smashups of gold ions—the nuclei of gold atoms that have been stripped of their electrons—routinely create a QGP by “melting” these nuclear building blocks so scientists can study the QGP’s properties.

Physicists originally thought that collisions of smaller ions with large ones wouldn’t create a QGP because the small ion wouldn’t deposit enough energy to melt the large ion’s protons and neutrons. But evidence from PHENIX has long suggested that these small collision systems generate particle flow patterns that are consistent with the existence of tiny specks of the primordial soup, the QGP.

Continuous cryogenic pellet injection system developed for tokamak fueling

A joint research team from Hefei Institutes of Physical Science of the Chinese Academy of Sciences has successfully developed a continuous cryogenic pellet injection system for tokamak fueling. This innovative system addresses key technical challenges associated with cryogenic ice formation, pellet cutting, and launching.

Cryogenic pellet injection is a state-of-the-art technique in fusion research. It involves condensing hydrogen isotopic gases into solid ice pellets, which are then accelerated and injected into plasma. This method allows for deep particle and high fueling efficiency, making it crucial for the future of fusion reactors.

It is recognized as a critical fueling technology for next-generation fusion devices, including the International Thermonuclear Experimental Reactor (ITER), the China Fusion Engineering Test Reactor (CFETR), and the European Demonstration Fusion Reactor (EU-DEMO).

A Geometric Theory of Everything

Deep down, the particles and forces of the universe are a manifestation of exquisite geometry.

By A. Garrett Lisi & James Owen Weatherall

Modern physics began with a sweeping unification: in 1687 Isaac Newton showed that the existing jumble of disparate theories describing everything from planetary motion to tides to pendulums were all aspects of a universal law of gravitation. Unification has played a central role in physics ever since. In the middle of the 19th century James Clerk Maxwell found that electricity and magnetism were two facets of electromagnetism. One hundred years later electromagnetism was unified with the weak nuclear force governing radioactivity, in what physicists call the electroweak theory.

Neutron star measurements place limits on color superconductivity in dense quark matter

At extremely high densities, quarks are expected to form pairs, as electrons do in a superconductor. This high-density quark behavior is called color superconductivity. The strength of pairing inside a color superconductor is difficult to calculate, but scientists have long known the strength’s relationship to the pressure of dense matter. Measuring the size of neutron stars and how they deform during mergers tells us their pressure and confirms that neutron stars are indeed the densest visible matter in the universe.

In a recent study, researchers used neutron star observations to infer the properties of quark matter at even higher densities where it is certain to be a color superconductor. This yields the first empirical upper bound on the strength of color superconducting pairing.

The work is published in the journal Physical Review Letters.

Quasiparticle research unlocks new insights into tellurene, paving the way for next-gen electronics

To describe how matter works at infinitesimal scales, researchers designate collective behaviors with single concepts, like calling a group of birds flying in sync a “flock” or “murmuration.” Known as quasiparticles, the phenomena these concepts refer to could be the key to next-generation technologies.

In a recent study published in Science Advances, a team of researchers led by Shengxi Huang, associate professor of electrical and computer engineering and materials science and nanoengineering at Rice, describe how one such type of quasiparticle—polarons—behaves in tellurene, a nanomaterial first synthesized in 2017 that is made up of tiny chains of tellurium atoms and has properties useful in sensing, electronic, optical and .

“Tellurene exhibits dramatic changes in its electronic and optical properties when its thickness is reduced to a few nanometers compared to its bulk form,” said Kunyan Zhang, a Rice doctoral alumna who is a first author on the study. “Specifically, these changes alter how electricity flows and how the material vibrates, which we traced back to the transformation of polarons as tellurene becomes thinner.”

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