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Category: particle physics – Page 12

Protein-like nanoparticles sort themselves inside growing crystals, enabling controlled release

The tiny bones in your fingers withstand countless taps and swipes thanks to a precise blend of materials. Flexible collagen fibers form the framework, reinforced by hard calcium phosphate hydroxyapatite crystals. This is just one of countless examples in which living organisms weave organic materials directly into inorganic crystals with exquisite precision. In a recent study published in Nature Communications, scientists attempted to recreate such precise spatial arrangements in biomimetic composite materials.

The researchers made two types of tiny diblock copolymer nanoparticles designed to mimic pseudo-proteins. The first consisted of solid spheres about 100 nanometers big, with a poly(benzyl methacrylate) core and a shell of sulfate-containing chains tagged with a red fluorescent dye. The second consisted of hollow, bubble-like particles about 300 nanometers across. They had the same polymer core but a carboxylate-rich outer shell tagged with a green fluorescent dye.

These tiny polymer nanoparticles, engineered with different sizes and compositions, much like protein molecules, sorted themselves naturally as growing calcite crystals trapped them. Instead of mixing randomly, the two types ended up in separate regions of the crystal, creating an artificial biomineral with a distinctly organized structure—all driven by differences in the nanoparticles’ surface chemistry.

Muon g-2 experiment places new constraints on a forbidden property of muons

A year after its final muon magnetic anomaly announcement, the Muon g-2 collaboration reports a new measurement of a different property of the muon: its electric dipole moment. The work is published on the arXiv preprint server.

Based on an analysis of 25% of Fermilab’s experimental data, this is the most sensitive direct search for a muon EDM ever accomplished. It is the first direct search for the muon EDM conducted at the U.S. Department of Energy’s Fermi National Accelerator Laboratory and only the third search worldwide in the past 50 years.

Searches for EDMs play a vital role in particle physics; detecting an EDM could be key to better understanding the matter-antimatter asymmetry required to explain the universe we see around us. This new result shows that if a muon EDM exists, it must be smaller than what the Muon g-2 experiment can currently detect.

Thermal detection of single photons using Dirac fermions

Single photon detectors are essential for various quantum and imaging applications. Here, the authors report graphene bolometers able to detect single near-infrared photons at temperatures up to 1.2 K with intrinsic quantum efficiency up to 87%, dark count  < 1 per second and effective noise equivalent power down to 2 × 10−22 W/ $$\sqrt{{{{\rm{Hz}}}}}$$ Hz.

Scientists Discover a Hidden Problem in Decades of Spacecraft Data

Different processes can produce similar spacecraft observations, making it difficult to determine how particles move through Earth’s radiation belt.

A spacecraft passing through Earth’s radiation belts can record particle behavior that looks random even when the underlying motion is highly organized. New research suggests that the limited resolution of spacecraft measurements can hide fine structures in high-energy particle populations, making predictable movement resemble diffusion.

The International Space Science Institute (ISSI) research team, led by the University of Birmingham and the Czech Academy of Science, reports in Physical Review Research that distinctly structured particle motion can produce observations nearly indistinguishable from patterns usually attributed to random scattering.

Scientists Detect a Nuclear Reactor’s Ghostly Signal After Shutdown

Antineutrinos from residual radioactive decay can reveal activity inside nuclear reactors even after they have been shut down.

A nuclear reactor does not become completely silent when it shuts down. Long after power production stops, radioactive, long-lived fission products continue decaying for months or years, releasing a faint stream of particles called antineutrinos. (Anti)neutrinos are the lightest and among the most elusive particles known in the Universe, passing through reactor structures and shielding with little obstruction.

The Double Chooz collaboration has now directly measured this lingering antineutrino emission for the first time. Led by Anthony Onillon and Thierry Lasserre of the Max-Planck-Institut für Kernphysik (MPIK) in Heidelberg, Germany, the research was recently published in Physical Review Letters.

MIT Physicists Zapped a Quantum Crystal With Lasers — and Discovered Something Surprising

MIT physicists have uncovered a surprising split in the behavior of electrons inside a quantum material: two nearly identical electronic patterns rebuild themselves in fundamentally different ways.

Electrons inside a solid do not always behave like independent particles. Under the right conditions, enormous numbers of them can reorganize together, producing entirely new states of matter with properties that the original material did not appear to possess.

MIT physicists have now watched that collective reorganization unfold in unusual detail. Their experiments reveal that two electronic phases occupying the same quantum material can form through fundamentally different mechanisms, even though both involve the same underlying type of electron order.

X-rays: Beyond the Nobel Prize limit

When certain atoms are irradiated with laser light, they can produce a very different kind of laser light: laser pulses with extremely high frequencies in the X-ray range. These laser pulses, which helped achieve record-breaking results at TU Wien in the 1990s, were the subject of the 2023 Nobel Prize in Physics.

However, the theoretical model of this effect makes a clear prediction: There is an upper limit to the energy, depending on the properties of the laser beam directed at the atoms. Above a certain value, known as the energy cutoff, hardly any X-rays are produced.

Now, however, a new experiment jointly performed by teams at TU Wien and the University of California San Diego has succeeded in overcoming this textbook cutoff rule: Using helium atoms, the researchers reached a much higher energy range than standard theory would allow. The reason lies in the interaction between the two electrons in the helium atom: They can release their energy simultaneously.

New CERN measurement challenges conventional models of how gluons behave inside atomic nuclei

A University of Kansas physicist played a leading role in a CERN study showing that two rival explanations for how gluons behave inside atomic nuclei can now be experimentally distinguished.

The research, carried out within the ALICE experiment at CERN’s Large Hadron Collider and published in Physical Review Letters, reports the first multidimensional measurement of incoherent J/ψ (pronounced “JAY-sigh”) photonuclear production as a function of both interaction energy and momentum transfer. The measurement gives scientists their clearest view yet of how gluons, the particles that bind quarks together, are arranged inside atomic nuclei at high energies.

“Although quarks are often described as the fundamental building blocks of matter, nearly all the mass of the visible universe—from the atoms in our bodies to the matter inside stars—actually comes from the energy carried by gluons and the strong force that binds quarks together,” said nuclear physicist Daniel Tapia Takaki, professor of physics & astronomy at KU and member of the ALICE collaboration. “Understanding how gluons behave inside nuclei is therefore essential to understanding how matter itself acquires its mass and structure.”

‘Flying focus’ laser overcomes key limitation in plasma-based particle accelerators

In a new Nature Physics study, researchers accelerated electrons to more than twice the energy predicted by the traditional dephasing limit for laser-plasma accelerators operating over the same distance. This was made possible by a specially engineered laser pulse called a flying focus, which counteracts a longstanding limitation known as “dephasing.”

Laser-plasma accelerators use an intense, ultrashort laser pulse to drive a wave of charge through a plasma. In principle, this makes it possible to accelerate particles to very high energies over just centimeters, rather than kilometers.

The problem is that the accelerating plasma wave cannot keep pace with the electrons riding it. The electrons move at speeds close to the speed of light, but the laser pulse driving the wave travels slightly slower. Over distance, the electrons manage to outrun the plasma wave. This dephasing causes the electrons to stop gaining energy, thereby affecting the amount of energy such accelerators can deliver.

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