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Category: particle physics – Page 519

Meteorite contains the oldest material on Earth: 7-billion-year-old stardust

Stars have life cycles. They’re born when bits of dust and gas floating through space find each other and collapse in on each other and heat up. They burn for millions to billions of years, and then they die. When they die, they pitch the particles that formed in their winds out into space, and those bits of stardust eventually form new stars, along with new planets and moons and meteorites. And in a meteorite that fell fifty years ago in Australia, scientists have now discovered stardust that formed 5 to 7 billion years ago-the oldest solid material ever found on Earth.

“This is one of the most exciting studies I’ve worked on,” says Philipp Heck, a curator at the Field Museum, associate professor at the University of Chicago, and lead author of a paper describing the findings in PNAS. “These are the oldest solid materials ever found, and they tell us about how formed in our galaxy.”

Mars’s Water Is Evaporating Away Even Faster Than We Expected

Billions of years ago, Mars could have been a planet very like Earth with copious liquid water on its surface. But over time, that water rose into Mars’s thin atmosphere and evaporated off into space. There are only very small amounts of water vapor left in the atmosphere today, and a new study shows that vapor is being lost even faster than previously believed.

The research, published in the journal Science, used data from the Trace Gas Orbiter in orbit around Mars to see how water moved up and down through the layers of the Martian atmosphere in order to understand how fast it evaporates away. They found that the vapor changes through the seasons and that in the warmer months the atmosphere hosts a whole lot more water than expected, in a state called “supersaturation.”

When the atmosphere becomes supersaturated, this makes the evaporation of water happen even faster. “Unconstrained by saturation, the water vapor globally penetrates through the cloud level, regardless of the dust distribution, facilitating the loss of water to space,” the authors explain. Even when the density of dust or ice particles in the atmosphere changes, that still doesn’t stop supersaturation, so the evaporation of water continues at a brisk pace.

Scientists Have Successfully Built a Particle Accelerator Onto a Silicon Chip

Particle accelerators like the Large Hadron Collider (LHC) are incredibly useful – and usually incredibly huge – instruments for studying some of the fundamentals of particle physics. But now scientists have managed to squeeze one on to a silicon chip.

It’s nowhere near as powerful as the bigger versions, as you might expect, but the new particle accelerator chip could still be very helpful for researchers who aren’t able to access gigantic particle accelerator setups.

While this first model is only a prototype, the team behind it is hopeful that it’s a first step towards providing a more compact alternative to the well-known massive particle accelerators, including the LHC and the SLAC National Accelerator Laboratory.

‘Superdiamond’ carbon-boron cages can trap and tap into different properties

A long-sought-after class of “superdiamond” carbon-based materials with tunable mechanical and electronic properties was predicted and synthesized by Carnegie’s Li Zhu and Timothy Strobel. Their work is published by Science Advances.

Carbon is the fourth-most– in the universe and is fundamental to life as we know it. It is unrivaled in its ability to form stable structures, both alone and with other elements.

A material’s properties are determined by how its are bonded and the structural arrangements that these bonds create. For -based materials, the type of bonding makes the difference between the hardness of diamond, which has three-dimensional “sp3” bonds, and the softness of graphite, which has two-dimensional “sp2” bonds, for example.

Brookhaven Lab chosen as site for multibillion-dollar collider

A multibillion-dollar high-speed atom smasher — an electron-ion collider that is capable of dissecting the mysterious subatomic material that forms the basis of everything in the universe — will be built at Brookhaven National Laboratory in Upton, federal authorities announced Thursday.

The collider will be the first of its kind in the United States. Gov. Andrew M. Cuomo said it would create about 4,000 construction jobs, retain 1,000 existing jobs at the lab and generate billions of dollars in economic activity for Long Island.

Officials with the U.S. Department of Energy said construction of the federally funded collider — which would be 2.4 miles in circumference, or 60% larger than the 1.5-mile Belmont Park horse race track, and one story underground — would cost $1.6 billion to $2.6 billion and take about a decade.

False Alarm: The So-Called ‘Angel Particle’ Is Still a Mystery

A 2017 report of the discovery of a particular kind of Majorana fermion — the chiral Majorana fermion, referred to as the “angel particle” — is likely a false alarm, according to new research. Majorana fermions are enigmatic particles that act as their own antiparticle and were first hypothesized to exist in 1937. They are of immense interest to physicists because their unique properties could allow them to be used in the construction of a topological quantum computer.

A team of physicists at Penn State and the University of Wurzburg in Germany led by Cui-Zu Chang, an assistant professor of physics at Penn State studied over three dozen devices similar to the one used to produce the angel particle in the 2017 report. They found that the feature that was claimed to be the manifestation of the angel particle was unlikely to be induced by the existence of the angel particle. A paper describing the research appears on January 3, 2020 in the journal Science.

“When the Italian physicist Ettore Majorana predicted the possibility of a new fundamental particle which is its own antiparticle, little could he have envisioned the long-lasting implications of his imaginative idea.”

Scientists Find Evidence a Strange Group of Quantum Particles Are Basically Immortal

Nothing lasts forever. Humans, planets, stars, galaxies, maybe even the Universe itself, everything has an expiration date. But things in the quantum realm don’t always follow the rules. Scientists have found that quasiparticles in quantum systems could be effectively immortal.

That doesn’t mean they don’t decay, which is reassuring. But once these quasiparticles have decayed, they are able to reorganise themselves back into existence, possibly ad infinitum.

This seemingly flies right in the face of the second law of thermodynamics, which asserts that entropy in an isolated system can only move in an increasing direction: things can only break down, not build back up again.

Clusters of gold atoms form peculiar pyramidal shape

Clusters composed of a few atoms tend to be spherical. They are usually organized in shells of atoms around a central atom. This is the case for many elements, but not for gold! Experiments and advanced computations have shown that freestanding clusters of twenty gold atoms take on a pyramidal shape. They have a triangular ground plane made up of ten neatly arranged atoms, with additional triangles of six and three atoms, topped by a single atom.

The remarkable tetrahedral structure has now been imaged for the first time with a scanning tunnelling microscope. This high-tech microscope can visualise single atoms. It operates at extremely low temperatures (269 degrees below zero) and uses quantum tunnelling of an electrical current from a sharp scanning metallic tip through the cluster and into the support. Quantum tunnelling is a process where electrical current flows between two conductors without any physical contact between them.

The researchers used intense plasmas in a complex vacuum chamber setup to sputter gold atoms from a macroscopic piece of gold. “Part of the sputtered atoms grow together to small particles of a few up to a few tens of atoms, due to a process comparable with condensation of water molecules to droplets,” says Zhe Li, the main author of the paper, currently at the Harbin Institute of Technology, Shenzhen. “We selected a beam of clusters consisting of exactly twenty gold atoms. We landed these species with one of the triangular facets onto a substrate covered with a very thin layer of kitchen salt (NaCl), precisely three atom layers thick.”

The study also revealed the peculiar electronic structure of the small gold pyramid. Similar to noble gas atoms or aromatic molecules, the cluster only has completely filled electron orbitals, which makes them much less reactive than clusters with one or a few atoms more or less.

Gold clusters ranging from a few to several dozens of atoms in size are known to possess remarkable properties.

Freestanding clusters of twenty gold atoms take the shape of a pyramid, researchers discovered. This is in contrast with most elements, which organize themselves by forming shells around one central atom.