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Category: particle physics

Physicists observe rare nuclear isomer in ytterbium-150 for first time

Nuclear isomers are crucial probes for studying the structure of nuclei. Unlike chemical isomers—which have the same chemical formula but different arrangements of atoms—nuclear isomers are nuclei that exist in a long-lived and relatively stable excited state.

Normally, an atomic nucleus resides in its lowest-energy state, known as the ground state. Under external perturbations, such as nucleus-nucleus collisions, however, a nucleus can be excited to a higher-energy state.

While most excited nuclear states are extremely short-lived and rapidly decay back to the ground state, some nuclei remain “trapped” in an excited state for a remarkably long time. Such isomeric states help reveal the structure of the nucleus due to its high sensitivity to the underlying shell structure as well as to changes in single-particle levels.

Emergent topological semimetal from quantum criticality

Consider a material that doesn’t just “have” a certain property, but spontaneously creates it out of total chaos. That is the essence of what researchers found in a recent study on a specific metal called CeRu4Sn6.

This isn’t just a lab curiosity. By proving that quantum fluctuations (the tiny, frantic jitters of atoms) can work together with a material’s symmetry to create new phases, the researchers have provided a new “treasure map.”

Key Takeaway: You don’t always need solid building blocks (quasiparticles) to build a structure; sometimes, the “jitter” of quantum physics is enough to weave a new reality.

Examples of materials with non-trivial band topology in the presence of strong electron correlations are rare. Now it is shown that quantum fluctuations near a quantum phase transition can promote topological phases in a heavy-fermion compound.

Jupiter’s Galilean moons may have gained life’s building blocks at birth

Southwest Research Institute was part of an international team that demonstrated how complex organic molecules (COMs), key chemical precursors to life, could have been incorporated into Jupiter’s Galilean moons during their formation. The team’s findings have resulted in complementary studies published in The Planetary Science Journal and Monthly Notices of the Royal Astronomical Society, offering new insights into the potential for life in the Jovian system.

How complex organics can form Carbon-rich compounds containing oxygen, nitrogen and other elements are necessary for living matter to form. Laboratory experiments have shown that COMs can form when icy grains containing methanol or mixtures of carbondioxide and ammonia are exposed to either ultraviolet radiation or moderate heating under conditions found in protoplanetary disks. These disks of gas and dust surround newly formed stars that eventually form planets.

“By combining disk evolution with particle transport models, we could precisely quantify the radiation and thermal conditions the icy grains experienced,” said Dr. Olivier Mousis of SwRI’s solar system science and exploration division, who is lead author of one of the two studies. “Then we directly compared our simulations with other laboratory experiments that produce COMs under realistic astrophysical conditions. The results showed that COM formation is possible in both the protosolar nebula environment and Jupiter’s circumplanetary disk.”

Asymmetric spin torque unlocks deterministic control of antiferromagnetic memory

A research team led by Prof. Shao Dingfu from the Hefei Institutes of Physical Science, Chinese Academy of Sciences, has proposed a universal mechanism that enables deterministic electrical control of collinear antiferromagnets—overcoming a long-standing bottleneck in antiferromagnetic spintronics. The study is published in Physical Review Letters.

Palm-sized superconducting magnet achieves 42 tesla, rivaling the world’s biggest

When we think of powerful magnets used in particle accelerators or for NMR (nuclear magnetic resonance), we often envision bulky machines, sometimes the size of buildings. But in an extraordinary breakthrough for physics, scientists at ETH Zurich have created magnets that are small enough to fit in the palm of your hand yet powerful enough to rival some of the world’s most powerful magnets.

Atom-thin material could help solve chip manufacturing problem

Making computer chips smaller is not just about better design. It also depends on a critical step in manufacturing called patterning, where nanoscale structures are carved into materials to form the circuits inside everything from smartphones to advanced sensors.

To create these patterns, engineers use a hard mask, a thin, durable material layer that protects selected regions while the exposed areas are etched away.

“As chips get smaller, the manufacturing process becomes much more demanding,” said Saptarshi Das, Penn State Ackley Professor of Engineering Science and professor of engineering science and mechanics. “The mask used to define these patterns must survive extremely harsh processing conditions. If the mask degrades, the patterns cannot be transferred reliably.”

Cosmic microwave background

(CMB, CMBR), or relic radiation, is microwave radiation that fills all space in the observable universe. With a standard optical telescope, the background space between stars and galaxies is almost completely dark. However, a sufficiently sensitive radio telescope detects a faint background glow that is almost uniform and is not associated with any star, galaxy, or other object. This glow is strongest in the microwave region of the electromagnetic spectrum. Its energy density exceeds that of all the photons emitted by all the stars in the history of the universe. The accidental discovery of the CMB in 1964 by American radio astronomers Arno Allan Penzias and Robert Woodrow Wilson was the culmination of work initiated in the 1940s.

The CMB is the key experimental evidence of the Big Bang theory for the origin of the universe. In the Big Bang cosmological models, during the earliest periods, the universe was filled with an opaque fog of dense, hot plasma of sub-atomic particles. As the universe expanded, this plasma cooled to the point where protons and electrons combined to form neutral atoms of mostly hydrogen. Unlike the plasma, these atoms could not scatter thermal radiation by Thomson scattering, and so the universe became transparent. Known as the recombination epoch, this decoupling event released photons to travel freely through space. However, the photons have grown less energetic due to the cosmological redshift associated with the expansion of the universe. The surface of last scattering refers to a shell at the right distance in space so photons are now received that were originally emitted at the time of decoupling.

The CMB is very smooth and uniform, but maps by sensitive detectors detect small but important temperature variations. Ground and space-based experiments such as COBE, WMAP and Planck have been used to measure these temperature inhomogeneities. The anisotropy structure is influenced by various interactions of matter and photons up to the point of decoupling, which results in a characteristic pattern of tiny ripples that varies with angular scale. The distribution of the anisotropy across the sky has frequency components that can be represented by a power spectrum displaying a sequence of peaks and valleys. The peak values of this spectrum hold important information about the physical properties of the early universe: the first peak determines the overall curvature of the universe, while the second and third peak detail the density of normal matter and so-called dark matter, respectively.

Fluid simulation at unprecedented scale provides toolkit for fundamental physics and applied fluid engineering

What governs the speed at which raindrops fall, sediment settles in river estuaries, and matter is ejected during a supernova? These questions circle around one, deceitfully simple factor: the rate at which a fluid filled with particles mixes with a particle-free one. Raindrops travel from one layer of air to another; sediment falls from river to seawater, and ejecta travels from the exploding star through the surrounding dust cloud. The same principle dictates sediment mixing in rising smoke, dust storms, nuclear explosions, hydrocarbon refining, metal smelting, wastewater treatment, and more.

New simulations have now provided researchers and engineers with unprecedented access to these fundamental fluid mechanics. While plainly visible in everyday life, the phenomenon has eluded scientific scrutiny due to their complexity. For the first time, researchers have derived a general formulation of how layers of heavy particles mix and described the common characteristics of the phenomena.

Simone Tandurella, study first author and Ph.D. student in the Complex Fluids and Flows Unit at OIST, explains, “Both the simulations and the model we obtain enable exciting research into a wide range of fundamental physics phenomena, as well as applied research in fluid engineering. They provide the basic puzzle pieces that can help us understand fluid-particle instabilities at large scales.”

Titanium complexes cleanly edit the core skeleton of highly stable organic compounds

Multi-titanium hydrides can selectively snip the strong structural bonds of stable organic molecules called pyridines, RIKEN researchers have shown. This discovery could guide designing catalysts for applications in multiple branches of industrial chemistry, from oil refining to the synthesis of functional organic molecules. The findings are published in the Journal of the American Chemical Society.

Pyridines are stable aromatic molecules characterized by a ring consisting of one nitrogen atom and five carbon atoms. They are a common structural motif in complex organic molecules such as pharmaceuticals. They are also a component of crude oil that needs to be removed during refining.

“The removal of nitrogen-containing impurities such as pyridines from crude oil is an important industrial process in petroleum refining,” notes Zhaomin Hou of the RIKEN Organometallic Chemistry Laboratory and the RIKEN Advanced Catalysis Research Group.

Compact vacuum ultraviolet laser may improve nanotechnology and power nuclear clocks

Physicists at the University of Colorado Boulder have demonstrated a new kind of vacuum ultraviolet laser that is 100 to 1,000 times more efficient than existing technologies of its kind. The researchers say the device could one day allow scientists to observe phenomena currently out of reach for even the most powerful microscopes—such as following fuel molecules in real time as they undergo combustion, spotting incredibly small defects in nanoelectronics and more.

The new laser might also allow for practical, ultraprecise nuclear clocks that rely on an energy transition in the nuclei of thorium atoms. These long sought-after devices could, theoretically, allow researchers to robustly track time with unprecedented precision.

The group is led by physicists Henry Kapteyn and Margaret Murnane, fellows of JILA, a joint research institute between CU Boulder and the U.S. National Institute of Standards and Technology (NIST). Jeremy Thurston, who earned his doctorate in physics from CU Boulder in 2024, spearheaded work on the new laser.

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