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Category: particle physics – Page 388

In a study recently published in Nature Nanotechnology, a research group led by Prof. Du Haifeng and Dr. Tang Jin from High Magnetic Field Laboratory, Hefei Institutes of Physical Science (HFIPS), reported a scientific breakthrough after they found skyrmion bundles, a new family member of topological magnetic structures.

With the help of Lorentz transmission electron microscopy (Lorentz-TEM), the research group clarified, for the first time, a type of magnetic quasiparticles with arbitrary topological charges Q, and then further realized current driven dynamic motion of bundles.

Skyrmion, a vortex-like localized chiral topological magnetic structure, has a potential to be the information carrier applied in future high-performance spintronic devices. The topological charge is a fundamental parameter of magnetic domains and determines their topology-related properties. Among the topological structures including skyrmions, merons, vortex, and skyrmion bubbles, the topological charges are both one or smaller than one. Although theory has proposed “skyrmion bags” and “high-order skyrmions” as multi-Q topological magnetic structures, their experimental observations remain elusive.

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Scientists at DESY have built a compact electron camera that can capture the inner, ultrafast dynamics of matter. The system shoots short bunches of electrons at a sample to take snapshots of its current inner structure. It is the first such electron diffractometer that uses Terahertz radiation for pulse compression. The developer team around DESY scientists Dongfang Zhang and Franz Kärtner from the Center for Free-Electron Laser Science CFEL validated their Terahertz-enhanced ultrafast electron diffractometer with the investigation of a silicon sample and present their work in the first issue of the journal Ultrafast Science, a new title in the Science group of scientific journals.

Electron diffraction is one way to investigate the inner structure of matter. However, it does not image the structure directly. Instead, when the electrons hit or traverse a solid sample, they are deflected in a systematic way by the electrons in the solid’s inner lattice. From the pattern of this diffraction, recorded on a detector, the internal lattice structure of the solid can be calculated. To detect dynamic changes in this inner structure, short bunches of sufficiently bright electrons have to be used. “The shorter the bunch, the faster the exposure time,” says Zhang, who is now a professor at Shanghai Jiao Tong University. “Typically, ultrafast electron diffraction (UED) uses bunch lengths, or exposure times, of some 100 femtoseconds, which is 0.1 trillionths of a second.”

Such short electron bunches can be routinely produced with high quality by state-of-the-art particle accelerators. However, these machines are often large and bulky, partly due to the radio frequency radiation used to power them, which operates in the Gigahertz band. The wavelength of the radiation sets the size for the whole device. The DESY team is now using Terahertz radiation instead with roughly a hundred times shorter wavelengths. “This basically means, the accelerator components, here a bunch compressor, can be a hundred times smaller, too,” explains Kärtner, who is also a professor and a member of the cluster of excellence “CUI: Advanced Imaging of Matter” at the University of Hamburg.

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Nobel laureate Steven Weinberg was one of the world’s foremost theoretical physicists and a passionate advocate for science. Among his many influential contributions is the co-discovery of the electroweak theory that unifies electromagnetism and the weak nuclear force, a central pillar in the Standard Model of Particle Physics. Join Brian Greene and physicist John Preskill as they pay tribute to Steven Weinberg and his profound contributions to science.

This program is part of the Big Ideas Series, made possible with support from the John Templeton Foundation.

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A new study by scientists has demonstrated how researchers may be able to create an accelerating jet of antimatter from light.

A team of physicists has shown that high-intensity lasers can be used to generate colliding gamma photons – the most energetic wavelengths of light – to produce electron-positron pairs. This, they say, could help us understand the environments around some of the Universe’s most extreme objects: neutron stars.

The process of creating a matter-antimatter pair of particles – an electron and a positron – from photons is called the Breit-Wheeler process, and it’s extremely difficult to achieve experimentally.

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Last month, Indiana’s Department of Transport (INDOT) announced a collaboration with Purdue University and German company Magment to test out whether cement with embedded magnetized particles could provide an affordable road-charging solution.

Most wireless vehicle charging technologies rely on a process known as inductive charging, where electricity pumped into a wire coil creates a magnetic field that can induce an electric current in any other nearby wire coil. The charging coils are installed at regular intervals under the road, and cars are fitted with a receiver coil that picks up the charge.

But installing thousands of miles of copper under the road is obviously fairly costly. Magment’s solution is to instead embed standard concrete with recycled ferrite particles, which are also able to generate a magnetic field but are considerably cheaper. The company claims its product can achieve transmission efficiency of up to 95 percent and can be built at “standard road-building installation costs.”

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A new way to probe exotic matter aids the study of atomic and particle physics.

Physicists have created a new way to observe details about the structure and composition of materials that improves upon previous methods. Conventional spectroscopy changes the frequency of light shining on a sample over time to reveal details about them. The new technique, Rabi-oscillation spectroscopy, does not need to explore a wide frequency range so can operate much more quickly. This method could be used to interrogate our best theories of matter in order to form a better understanding of the material universe.

Though we cannot see them with the naked eye, we are all familiar with the atoms that make up everything we see around us. Collections of positive protons, neutral neutrons and negative electrons give rise to all the matter we interact with. However, there are some more exotic forms of matter, including exotic atoms, which are not made from these three basic components. Muonium, for example, is like hydrogen, which typically has one electron in orbit around one proton, but has a positively charged muon particle in place of the proton.

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Majoranas particles found.

Majorana particles have been getting bad publicity: a claimed discovery in ultracold nanowires had to be retracted. Now Leiden physicists open up a new door to detecting Majoranas in a different experimental system, the Fu-Kane heterostructure, they announce in Physical Review Letters.

Majorana particles are quasiparticles: collective movements of particles (electrons in this case) which behave as single particles. If detected in real life, they could be used to build stable quantum computers.

“Majoranas are quantum mechanical superpositions,” explains Gal Lemut. This superposition, a special kind of combination, comprises an electron and a hole (a place in a crystal where an electron is missing.

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Scientists have created key parts of synthetic brain cells that can hold cellular “memories” for milliseconds. The achievement could one day lead to computers that work like the human brain.

These parts, which were used to model an artificial brain cell, use charged particles called ions to produce an electrical signal, in the same way that information gets transferred between neurons in your brain.

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