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Archive for the ‘particle physics’ category: Page 89

Feb 10, 2023

MIT Engineers Grow “Perfect” Atom-Thin Materials

Posted by in categories: computing, particle physics

Adhering to Moore’s Law, the number of transistors on a microchip has doubled annually since the 1960s, but this growth is expected to reach its limit as silicon, the foundation of modern transistors, loses its electrical properties when devices made from it dip below a certain size.

Enter 2D materials — delicate, two-dimensional sheets of perfect crystals that are as thin as a single atom.

An atom is the smallest component of an element. It is made up of protons and neutrons within the nucleus, and electrons circling the nucleus.

Feb 9, 2023

Atom-thin walls could smash size, memory barriers in next-gen devices

Posted by in categories: computing, neuroscience, particle physics

For all of the unparalleled, parallel-processing, still-indistinguishable-from-magic wizardry packed into the three pounds of an adult human brain, it obeys the same rule as the other living tissue it controls: Oxygen is a must.

So it was with a touch of irony that Evgeny Tsymbal offered his explanation for a technological wonder—movable, data-covered walls mere atoms wide—that may eventually help computers behave more like a brain.

“There was unambiguous evidence that oxygen vacancies are responsible for this,” said Tsymbal, George Holmes University Professor of physics and astronomy at the University of Nebraska–Lincoln.

Feb 9, 2023

Searching for Ghost Particles with a Mechanical Sensor

Posted by in categories: nanotechnology, particle physics, quantum physics

Researchers have learned much about neutrinos over the past few decades, but some mysteries remain unsolved. For example, the standard model predicts that neutrinos are massless, but experiments say otherwise. One possible solution to this mass mystery involves another group of neutrinos that does not interact directly via the weak nuclear force and is therefore extremely difficult to detect. David Moore of Yale University and his colleagues have proposed a way to search for these so-called sterile neutrinos using a radioactive nanoparticle suspended in a laser beam [1].

Moore and his colleagues suggest levitating a 100-nm-diameter silica sphere in an optical trap and cooling it to its motional ground state. If the nanoparticle is filled with nuclei that decay by emitting neutrinos—such as certain argon or phosphorous isotopes—then electrons and neutrinos zipping from decaying nuclei should give it a momentum kick. By measuring the magnitude of this kick, the team hopes to determine the neutrinos’ momenta. Although most of these neutrinos will be the familiar three neutrino flavors, sterile neutrinos—if they exist—should also occasionally be emitted, producing unexpectedly small momentum kicks. Moore says that monitoring a single nanoparticle for one month would equate to a sterile-neutrino sensitivity 10 times better than that of any experiment tried so far.

Moore and his team are currently working on a proof-of-principle experiment using alpha-emitting by-products of radon, which result in a larger momentum kick. Once the techniques are optimized, they expect that switching to beta-decaying isotopes will let them see heavy sterile neutrinos in the 0.1–1 MeV mass range. Introducing more quantum tricks to manipulate the nanoparticle’s quantum state will make future experiments sensitive to even lighter sterile neutrinos.

Feb 8, 2023

Breaking: Researchers at CERN break “The Speed of Light”

Posted by in category: particle physics

Scientists said on Thursday they recorded particles travelling faster than light – a finding that could overturn one of Einstein’s fundamental laws of the universe. Antonio Ereditato, spokesman for the international group of researchers, saidthat measurements taken over three years showed neutrinos pumped from CERN near Geneva to Gran Sasso in Italy had arrived 60 nanoseconds quicker than light would have done.

“We have high confidence in our results. We have checked and rechecked for anything that could have distorted our measurements but we found nothing,” he said. “We now want colleagues to check them independently.”

If confirmed, the discovery would undermine Albert Einstein’s 1905 theory of special relativity, which says that the speed of light is a “cosmic constant” and that nothing in the universe can travel faster. That assertion, which has withstood over a century of testing, is one of the key elements of the so-called Standard Model of physics, which attempts to describe the way the universe and everything in it works. The totally unexpected finding emerged from research by a physicists working on an experiment dubbed OPERA run jointly by the CERN particle research center near Geneva and the Gran Sasso Laboratory in central Italy.

Feb 8, 2023

Supercooled Drops Have Rocket-Like Propulsion

Posted by in categories: chemistry, particle physics, space travel

Claudiu Stan of Rutgers University—Newark, New Jersey, and his colleagues were watching moving drops of supercooled water spontaneously freeze when they noticed something unexpected: drops kept suddenly disappearing. Initially they thought that the lost drops had shattered as they froze. But, on closer inspection, they found that the icy drops were still there, they had just moved out of view. The team has now developed a quantitative model for this behavior, attributing it to a rocket-like propulsion mechanism induced by the freezing process [1]. Stan says that the finding could inspire scientists to design self-propelled systems powered by such phase transitions.

The team’s results add to a growing body of work on self-propelled drops. The mechanisms behind such motion vary wildly, but Stan notes that they all involve symmetry breaking. For the freezing drops, this symmetry breaking arises when the ice nucleation starts off-center. When ice nucleates, the change in structure releases latent heat, causing the local evaporation rate to suddenly increase, and if the nucleation is off-center, this enhanced evaporation occurs unevenly over the drop’s surface. Like a rocket ejecting a propellant heated by a chemical reaction, this asymmetrical evaporation increases the drop’s momentum, with the team’s model predicting peak velocities of nearly 1 m/s.

Stan says that this propulsion mechanism has a unique feature that could make it attractive for applications: unlike most self-propelled particles, it requires no surfaces and no surrounding fluid (the experiments were done under vacuum). But, for him, the findings have another bonus: “I am a fan of space exploration, so it was exciting to realize that [we could] draw an analogy between these tiny droplets and rockets,” he says.

Feb 8, 2023

How Sea Spray Might Disperse Large Particles

Posted by in category: particle physics

Experiments reveal new details of the process by which contaminants in the ocean could reach the atmosphere through the bursting of bubbles in foam.

The bursting bubbles in ocean foam produce a mist of droplets that can contain enhanced concentrations of ocean pollutant particles. In single-bubble lab experiments, researchers have now shown that the inclusion of a particular particle in an airborne droplet depends on some details of the fluid motion that occurs when the droplet forms [1]. The researchers measured the efficiency with which particles are transferred to droplets and also ran simulations of the fluid motion. Their model predicts that the airborne droplets should contain more large particles, such as microplastics, and fewer smaller particles, such as viruses, than expected based on previous theories.

The droplets produced by bursting air bubbles in ocean foam provide the atmosphere’s main source of ocean-originated particles, including pollutants and bacteria, and environmental scientists want to understand this ocean-to-atmosphere transfer process in detail. Experiments in the 1970s showed that bursting bubbles transport pathogens into the environment and also that the droplets produced contain these particles at high concentrations.

Feb 7, 2023

New horizons for organoboron and organosilicon chemistry with triple elementalization

Posted by in categories: chemistry, particle physics

In recent years, organic chemicals containing boron (B) and silicon (Si) have found applications in various fields, including optoelectronics and pharmaceuticals. Moreover, they can also serve as building blocks for complex organic chemicals. As a result, scientists are actively looking for new ways to leverage these versatile chemical tools as well as produce more kinds of organosilicon and organoboron compounds.

One limitation of the synthesis methods currently available for these chemicals is that we cannot introduce multiple B-and Si-containing groups in aromatic heterocycles, i.e., carbon rings in which one of the is replaced by a nitrogen atom. If we could produce and freely transform such molecules, it would unlock the synthesis of several compounds relevant in medicinal chemistry.

Fortunately, a research team including Assistant Professor Yuki Nagashima from Tokyo Institute of Technology (Tokyo Tech), Japan has found a straightforward way around this limitation. As explained in their most recent study published in Nature Communications, the team has developed a method that allows them to modify quinolines, small organic molecules with an aromatic nitrogen heterocycle, with B-, Si-, and carbon-containing groups simultaneously.

Feb 7, 2023

Watch nuclear fusion reactor form plasma: “You can’t take your eyes off it”

Posted by in categories: nuclear energy, particle physics, space travel

What does the inside of a nuclear fusion reactor look like?

“It looks like the future,” Stuart White, head of communications at Tokamak Energy, told Newsweek. “A spaceship. It’s extremely striking, powerful and exciting. You can’t take your eyes off it.”

Nuclear fusion is a technology that creates energy in the same way as the sun: it occurs when two atoms are thrust together with such force that they combine into a single, larger atom and release huge amounts of energy in the process.

Feb 7, 2023

Underdog technologies gain ground in quantum-computing race

Posted by in categories: computing, particle physics, quantum physics

Individual atoms trapped by optical ‘tweezers’ are emerging as a promising computational platform.

Feb 7, 2023

Rabi oscillations in a stretching molecule

Posted by in categories: particle physics, quantum physics

Over eighty years ago, Rabi oscillations were proposed to describe the strong coupling and population transfer in a two-level quantum system exposed to an oscillatory driving field. As compared to atoms, molecules have an extra degree of vibration, which adds an additional knob to the Rabi oscillations in light-molecule interactions. However, how such a laser-driven Rabi oscillation during the stretching of molecular bonds determines the kinetic energy release (KER) spectrum of dissociative fragments is still an open question.

In a new article published in Light: Science & Applications, a joint team of scientists, led by Professor Feng He from Shanghai Jiao Tong University and Professor Jian Wu from East China Normal University has investigated Rabi oscillations in a stretching molecule and discovered the strong-field-induced dissociation dynamics beyond the well-accepted resonant one-photon dissociation scenario. During the dissociation of the simplest molecular ion of H2+, coupled with the laser field, the electron hops between the 1sσg and 2pσu states, forming the Rabi oscillations.

The ionization-created nuclear wave packet (NWP) may propagate alternatively along the two potential energy curves towards a larger internuclear distance monotonically, termed as the rolling process, or may propagate outwards along the 2pσu curve followed by the inward propagation in the 1sσg curve and then be relaunched to 2pσu state again followed by subsequent dissociation, termed as the looping process. The rolling and looping dissociation pathways lead to different KERs of the ejected dissociative fragments, which have been verified by comparing experimental measurements with quantum simulation results.

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