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Category: particle physics – Page 10

Scientists Reveal Hidden Structure of a Quantum Fluid

Bose-Einstein Condensates (BECs) are often described as a “fifth state of matter”: a quantum state in which many particles lose their individual identities and behave as one collective object. For more than 60 years, researchers have sought to create such condensates from excitons — electron-hole pairs — as a solid-state route to macroscopic quantum coherence, which is useful for quantum technologies. This has been difficult to realize in controllable semiconductor devices because optically generated excitons have very short lifespans of around a billionth of a second, and BECs are normally attained with supercold gasses in a vacuum.

But now, a team led by Lawrence Berkeley National Laboratory (Berkeley Lab) has observed a tunable BEC of excitons at high temperature in an atomically thin semiconductor. The findings, published in Nature, reveal not only that the excitons form a BEC, but also that the condensate has an internal structure that can be switched by a magnetic field.

Magnetic dopants help quantum dots use light for chemical reactions

Scientists at Los Alamos National Laboratory have demonstrated a new quantum-dot mechanism that could significantly expand the reach of light-driven chemistry. By introducing magnetic manganese dopants into semiconductor quantum dots, the team created an ultrafast spin-exchange pathway that captures hot-electron energy before it is lost as heat and uses it to drive chemical reduction.

The work, published in Nature Communications, provides a direct demonstration that magnetic dopants can enable efficient hot-electron reduction in quantum dots. Using methyl viologen as a model molecular acceptor, the researchers showed that manganese-doped quantum dots can transfer electrons significantly faster than undoped particles and can drive reduction even when conventional band-edge energetics are unfavorable.

“Our study shows that magnetic dopants can do much more than modify the optical properties of quantum dots,” says Victor Klimov, laboratory fellow at Los Alamos and principal investigator on the project. “They can capture hot-exciton energy on ultrafast time scales and redirect it into useful chemistry, which opens a fundamentally new route to high-energy photoreduction.”

Chinese observatory identifies most powerful cosmic particle accelerator ever detected

Researchers working at the Large High Altitude Air Shower Observatory (LHAASO) in China’s Sichuan Province have discovered that the unique binary system Cygnus X-3, located in the constellation Cygnus, is the most powerful particle accelerator known to date. The findings were reported by Xinhua News Agency, a TV BRICS partner, citing the Institute of High Energy Physics of the Chinese Academy of Sciences.

Cygnus X-3 is a binary system consisting of either a black hole or a neutron star and a massive companion star. The compact object actively accretes material from the powerful stellar wind of its companion, accelerating particles to extremely high energies.

Scientists had previously believed that charged particles within the Milky Way could reach energies of around one petaelectronvolt (PeV). However, a detailed analysis of ultra-high-energy gamma-ray emissions enabled LHAASO researchers to determine that Cygnus X-3 is capable of accelerating cosmic rays to energies of at least 30 petaelectronvolts. The team also detected a periodic ultra-high-energy gamma-ray signal with a cycle of 4.8 hours and established that the particle acceleration region is located approximately three solar radii from the source of the radiation.

Ultrafast X-ray flashes partially reverse the damage they cause, enabling brighter, more accurate imaging

The interaction between X-rays and matter can be actively controlled, according to an international research team led by the University of Hamburg and SLAC National Accelerator Laboratory that has succeeded in producing bright X-ray images with significantly less damage. In an article published in Nature Communications, the researchers report using ultrafast pulses that partially reverse the damage they generate.

X-rays are ionizing radiation and can damage virtually all matter. That is why radiologists strive to keep the X-ray dose in imaging as low as possible. At the same time, they must ensure the image is bright enough and contains sufficient detail for diagnosis. This trade-off has shaped X-ray imaging for decades.

Researchers who want to image chemical reactions in individual molecules and nanoparticles face a far more extreme version of the same problem. To capture something as small and fleeting as a reaction within a cluster of atoms, they must illuminate the sample with a large number of X-ray photons in an extremely short burst. The most advanced tools for this—X-ray free-electron lasers (XFELs)—produce flashes short enough to “outrun” the physical destruction of the sample.

Scientists reveal the hidden force driving the universe’s hottest fluid

When atomic nuclei crash into one another at nearly the speed of light, they briefly produce quark-gluon plasma, an extraordinarily hot state of matter in which quarks and gluons can move freely. This exotic material behaves like an almost perfect fluid and offers scientists a way to study conditions similar to those that existed shortly after the Big Bang.

Researchers have devoted considerable attention to the plasma’s intense swirling motion and powerful electromagnetic fields. Its acceleration, however, has received far less scrutiny, even though it directly contributes to the fireball’s rapid expansion. In hydrodynamics, acceleration is considered just as fundamental as vorticity, much as electric and magnetic fields are treated as equally important parts of electromagnetism.

CERN Experiments Detect Signs of the Universe’s Primordial Matter

All four major LHC experiments have found new evidence that collisions between oxygen and neon may produce the extreme state of matter that existed during the first microseconds after the Big Bang.

Inside the Large Hadron Collider (LHC), collisions between relatively light oxygen and neon nuclei may be producing matter from the earliest moments of the Universe. One year after the collider’s first oxygen runs, all four major LHC experiments, ALICE, ATLAS, CMS, and LHCb, have reported signs of quark–gluon plasma (QGP).

QGP forms under immense pressure at temperatures more than 100,000 times hotter than the center of the Sun. In these conditions, composite particles break apart into quarks and the gluons that normally bind them together. This state of matter is thought to have filled the Universe during the first millionths of a second after the Big Bang. Nearly 14 billion years later, physicists can briefly recreate it through high-energy nuclear collisions at the LHC.

Randomly mixed atoms arranged in rows and columns for sustainable catalysis

The energy system of the future will require sustainable catalysts that, for example, enable the efficient production of green hydrogen. Materials consisting of mixtures of five chemical elements show great promise for enabling ideal catalysts in the future.

Magnetic nanoparticles remove forever chemicals from water

PFAS, otherwise known as forever chemicals, have become commonplace in numerous everyday and industrial products. At the same time, they are some of the most problematic pollutants of our times: They are extremely durable, accumulate in the environment and in organisms and can only be removed from water with difficulty.

A team of researchers from FAU, Uniklinikum Erlangen and the Bavarian Health and Food Safety Authority led by Prof. Dr. Marcus Halik from the Chair of Polymer Materials at FAU have developed a procedure to efficiently remove a wide range of different PFAS from water using functionalized magnetic nanoparticles. They have published their findings in the journal Materials Today.

Johannes Voß and Linda Rockmann from Halik’s team developed functionalized iron oxide nanoparticles with unique magnetic properties, whose surface was specifically adapted to bind to various PFAS. Once they are attached to the iron oxide, i.e. rust particles, the PFAS can simply be removed from the water using a magnet.

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