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Category: particle physics – Page 20

Just as sailboats are powered by the wind, space scientists and engineers dream of a day when spacecraft can be powered by solar sails

How would this work? The Sun blasts out radiation all the time. Radiation that strikes a large, shiny, sail-like structure would push on it, much as the wind pushes on a sailboat. Although the push would be very gentle, it would be constant. Over time, the spacecraft would be going very, very fast, using no fuel at all!

You may have heard of the “solar wind.” Solar wind is made of particles blasted out from the Sun. Solar sails do not “catch the solar wind.” Instead, solar sails use the force of the light itself. This force is much stronger than the force from the solar wind.

Mysterious Cygnus Bubble may trace back to microquasar, astronomers suggest

Astronomers have proposed a new explanation for the mysterious Cygnus Bubble, a vast cloud of ultra-high-energy gamma rays stretching thousands of light-years across the sky. While the bubble has generally been linked to the Cygnus X star-forming region, the new study argues that a microquasar more naturally explains its highest-energy emission. The results were published in a paper in The Astrophysical Journal Letters on July 21.

For years, astronomers have puzzled over the sources of the highest-energy cosmic rays in our galaxy—particles accelerated to a quadrillion electron volts, or a petaelectronvolt (PeV; that’s 15 zeros after 1). These sources are called Galactic PeVatrons, and they are notoriously hard to pin down. In principle, all kinds of astrophysical objects violent enough to accelerate particles to extreme energies could be PeVatrons: supernova remnants, pulsar wind nebulae, star clusters or binary star systems.

The accelerated particles travel outward and light up with ultra-high-energy gamma rays wherever they eventually slam into ambient gas, sometimes hundreds to thousands of light-years from their true source. One of the most striking gamma-ray structures in the sky, the “Cygnus Bubble,” has long been attributed to a nearby cluster of massive, young stars in the Cygnus X star-forming region, some 4,600 light-years away.

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.

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