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Category: particle physics – Page 390

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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Circa 2020

The basic idea behind all nuclear power plants is the same: Convert the heat created by nuclear fission into electricity. There are several ways to do this, but in each case it involves a delicate balancing act between safety and efficiency. A nuclear reactor works best when the core is really hot, but if it gets too hot it will cause a meltdown and the environment will get poisoned and people may die and it will take billions of dollars to clean up the mess.

The last time this happened was less than a decade ago, when a massive earthquake followed by a series of tsunamis caused a meltdown at the Fukushima Daiichi power plant in Japan. But a new generation of reactors coming online in the next few years aims to make these kinds of disasters a thing of the past. Not only will these reactors be smaller and more efficient than current nuclear power plants, but their designers claim they’ll be virtually meltdown-proof. Their secret? Millions of submillimeter-size grains of uranium individually wrapped in protective shells. It’s called triso fuel, and it’s like a radioactive gobstopper.

Triso— short for “tristructural isotropic”—fuel is made from a mixture of low enriched uranium and oxygen, and it is surrounded by three alternating layers of graphite and a ceramic called silicon carbide. Each particle is smaller than a poppy seed, but its layered shell can protect the uranium inside from melting under even the most extreme conditions that could occur in a reactor.

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Physicists at the National Institute of Standards and Technology (NIST) have linked together, or “entangled,” the mechanical motion and electronic properties of a tiny blue crystal, giving it a quantum edge in measuring electric fields with record sensitivity that may enhance understanding of the universe.

The quantum sensor consists of 150 beryllium ions (electrically charged atoms) confined in a magnetic field, so they self-arrange into a flat 2D crystal just 200 millionths of a meter in diameter. Quantum sensors such as this have the potential to detect signals from dark matter — a mysterious substance that might turn out to be, among other theories, subatomic particles that interact with normal matter through a weak electromagnetic field. The presence of dark matter could cause the crystal to wiggle in telltale ways, revealed by collective changes among the crystal’s ions in one of their electronic properties, known as spin.

As described in the August 6, 2021, issue of Science, researchers can measure the vibrational excitation of the crystal — the flat plane moving up and down like the head of a drum — by monitoring changes in the collective spin. Measuring the spin indicates the extent of the vibrational excitation, referred to as displacement.

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2D form of carbon transforms into a high-temperature superconductor if placed near a Bose-Einstein condensate, say theorists.

Graphene can be made to superconduct by placing it next to a Bose-Einstein condensate – a form of matter in which all the atoms are in the same quantum state. According to the theorists who discovered it, this new type of superconductivity stems from interactions between the electrons in graphene and quasiparticles called “bogolons” in the condensate. If demonstrated experimentally, the work could make it possible to develop new types of hybrid superconducting devices for applications in quantum sensing and quantum computing.

Conventional superconductivity occurs when phonons – quasiparticles that arise from vibrations in a material’s crystal lattice – cause electrons in the material to pair up despite their mutual electromagnetic repulsion. If the material is cooled to sufficiently low temperatures, these paired electrons (known as Cooper pairs) can travel through it without any resistance.

Bose-Einstein condensates (BECs) form when bosons, or particles with integer quantum spin, are cooled until they are all in the same quantum state. Within this special “fifth state of matter”, quasiparticles called Bogoliubov excitations can develop. Named after the Russian physicist Nikolaï Bogoliubov, who was the first to provide a theoretical description of them, these quasiparticles are usually known as bogolons. Ivan Savenko, who led the research at the Institute for Basic Science (IBS) in Korea, explains that bogolons are similar to phonons in the sense that they also serve as mediators for electron-electron attractions.

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The scientists found evidence that “beauty” quarks do not decay in the way they should following the Standard Model.

Beauty quarks, particles similar to but heavier than electrons, interact with all forces in the same way, so they should decay into muons and electrons at the same rate.

However, the data collected by the LHCb seems to show that these quarks are decaying into muons less often than they decay into electrons, which should only be possible if unknown particles are interfering and making them more likely to decay into electrons.

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One of the biggest factors affecting consumer adoption of electric vehicles (EVs) is the amount of time required to recharge the vehicles—usually powered by lithium-ion batteries. It can take up to a few hours or overnight to fully recharge EVs, depending on the charging method and amount of charge remaining in the battery. This forces drivers to either limit travel away from their home chargers or to locate and wait at public charging stations during longer trips.

Why does it take so long to fully charge a battery, even those used to power smaller devices, such as mobile phones and laptops? The primary reason is that devices and their chargers are designed so the rechargeable lithium-ion batteries charge only at slower, controlled rates. This is a safety feature to help prevent fires, and even explosions, due to tiny, rigid tree-like structures, called dendrites, that can grow inside a lithium battery during fast charging and induce short-circuits inside the battery.

To address the need for a more practical lithium-ion battery, researchers from the University of California San Diego (UC San Diego) worked with scientists at Oak Ridge National Laboratory (ORNL) to conduct neutron scattering experiments on a new type of material that could be used to make safer, faster-charging batteries. The researchers produced samples of lithium vanadium oxide (Li3V2O5), a “disordered rock salt” similar to table salt but with a certain degree of randomness in the arrangement of its atoms. The samples were placed in a powerful neutron beam that enabled observing the activity of ions inside the material after a voltage was applied.

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Particle accelerators are hugely important in the study of the matter of the Universe, but the ones we think of tend to be gigantic instruments – surrounding cities in some cases. Now scientists have made a much smaller version to power an advanced laser, a setup that could be just as useful as its larger counterparts.

The particle accelerator in question is a plasma wakefield accelerator, which generates short and intense bursts of electrons, and the laser it’s powering is what’s known as a free-electron laser (FEL), which uses its light to analyze atoms, molecules, and condensed matter in incredibly high resolutions.

While this scenario has been tried before, the resulting laser light hasn’t been intense enough to be useful at smaller scales. Here, the researchers were able to keep the setup enclosed in few normal-sized rooms while amplifying the final electron beam produced by the laser, increasing the intensity by 100 times in the last step of the process.

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