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Category: particle physics – Page 410

Scientists at the US Department of Energy’s Argonne National Laboratory have found a way to use diamonds and graphene to create a new material combination that demonstrates so-called superlubricity.

Led by nanoscientist Ani Sumant of Argonne’s Center for Nanoscale Materials (CNM) and Argonne Distinguished Fellow Ali Erdemir of Argonne’s Energy Systems Division, the Argonne team combined diamond nanoparticles, small patches of graphene, and a diamond-like carbon material to create superlubricity, a highly-desirable property in which friction drops to near zero.

According to Erdemir, as the graphene patches and diamond particles rub up against a large diamond-like carbon surface, the graphene rolls itself around the diamond particle, creating something that looks like a ball bearing on the nanoscopic level.

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Circa 2017

Data storage technology continues to shrink in size and grow in capacity, but scientists have just taken things to the next level — they’ve built a nanoscale hard drive using a single atom.

By magnetising an atom, cooling it with liquid helium, and storing it in an extreme vacuum, the team managed to store a single bit of data (either a 1 or a 0) in this incredibly miniscule space.

Continue reading “IBM Seriously Just Turned an Atom Into The World’s Smallest Hard Drive” | >

Researchers from the UK’s Durham University and Germany’s Fraunhofer Institute claim they’ve come up with the world’s first manufactured non-cuttable material, just 15 percent the density of steel, which they say could make for indestructible bike locks and lightweight armor.

The material, named Proteus, uses ceramic spheres in a cellular aluminum structure to foil angle grinders, drills and the like by creating destructive vibrations that blunt any cutting tools used against it. The researchers took inspiration from the tough, cellular skin of grapefruit and the hard, fracture-resistant aragonite shells of molluscs in their creation of the Proteus design.

An angle grinder or drill bit will cut through the outer layer of a Proteus plate, but once it reaches the embedded ceramic spheres, the fun begins with vibrations that blunt the tool’s sharp edges, and then fine particles of ceramic dust begin filling up gaps in the matrix-like structure of the metal. These cause it to become even harder the faster you grind or drill “due to interatomic forces between the ceramic grains,” and “the force and energy of the disc or the drill is turned back on itself, and it is weakened and destroyed by its own attack.”

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In recent years, several research teams worldwide have been trying to develop a new class of devices known as spintronics or spin transport electronics. These devices can encode, store, process and transmit data using the spin of electrons in certain materials.

The operation of spintronics relies on magneto-transport effects, such as (GMR) and tunneling (TMR), which enable the transport of electrons through a given material in the form of a magnetic field. A device is generally made of two conductive ferromagnetic layers separated by a non-magnetic metal layer (i.e., a spin valve) or an insulator layer (i.e., a ).

Magneto-transport effects, which occur in a device’s spin valves and magnetic tunnel junctions, result in a relatively low resistance when the two magnetic layers are parallel and a relatively high resistance state when they are not. These effects are crucial to the functioning of many contemporary storage devices, including and magnetic random access memories (MRAMs).

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The Fermilab magnet team has done it again. After setting a world record for an accelerator magnet in 2019, they have broken it a year later.

In a June 2020 test, a demonstrator magnet designed and built by the magnet team at the Department of Energy’s Fermilab achieved a 14.5-tesla field strength for an accelerator steering dipole magnet, surpassing their previous record of 14.1 T.

This test is an important step toward addressing the demanding magnet requirements of a future hadron collider under discussion in the particle physics community. If built, such a collider would be four times larger and almost eight times more powerful than the 17-mile-circumference Large Hadron Collider at the European laboratory CERN, which operates at a steering field of 7.8 T. Current future-collider designs estimate the field strength for a steering magnet — the magnet responsible for bending particle beams around a curve — to be up to 16 T.

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Magnetically separating waste particles makes it possible to reclaim a variety of raw materials from waste. Using a magnetic fluid, a waste flow can be separated into multiple segments in a single step. Researchers from Utrecht and Nijmegen have now succeeded in creating a magnetic fluid that remains stable in extremely strong magnetic fields, which makes it possible to separate materials with a high density, such as electronic components. The results have recently been published in The Journal of Physical Chemistry Letters.

Magnetic density separation

When you drop a stone and a wooden ball into a basin of , the stone will sink while the ball floats on the surface. This is because the two objects have different densities: the stone is more dense than the water, while the wood is less dense. That principle is also used in magnetic density separation (MDS), except that instead of using water—which has a fixed density—it uses a magnetic fluid with an effective density that can change in relation to its distance from a magnet: it has a higher apparent density at less distance to the magnet. As a result, waste particles of different densities float at different depths in the fluid.

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This is the third in a series. Read part 1 here and part 2 here.

One of the most notable features of Eric Lerner’s approach to fusion using the Dense Plasma Focus (DPF), presented in Part 1 and Part 2 of this series, lies in the possibility of using hydrogen and boron as a fuel. This property is shared by the hydrogen-boron laser fusion reactor, which I discussed in a previous series of articles in Asia Times.

Among other things, the fusion reaction between nuclei of hydrogen and boron is aneutronic: no neutrons are produced, but only charged alpha particles. This gives the DPF enormous potential advantages over the mainline fusion technologies, which are all designed to employ a mixture of the hydrogen isotopes deuterium (D) and tritium (T) as their fuel.

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A new device that relies on flowing clouds of ultracold atoms promises potential tests of the intersection between the weirdness of the quantum world and the familiarity of the macroscopic world we experience every day. The atomtronic Superconducting QUantum Interference Device (SQUID) is also potentially useful for ultrasensitive rotation measurements and as a component in quantum computers.

“In a conventional SQUID, the quantum interference in electron currents can be used to make one of the most sensitive detectors,” said Changhyun Ryu, a physicist with the Material Physics and Applications Quantum group at Los Alamos National Laboratory. “We use rather than charged electrons. Instead of responding to magnetic fields, the atomtronic version of a SQUID is sensitive to mechanical rotation.”

Although small, at only about 10 millionths of a meter across, the atomtronic SQUID is thousands of times larger than the molecules and atoms that are typically governed by the laws of quantum mechanics. The relatively large scale of the device lets it test theories of macroscopic realism, which could help explain how the world we are familiar with is compatible with the quantum weirdness that rules the universe on very small scales. On a more pragmatic level, atomtronic SQUIDs could offer highly sensitive rotation sensors or perform calculations as part of quantum computers.

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The researchers used powerful laser flashes to irradiate thin, films of crystalline materials. These laser pulses drove crystal electrons into a fast wiggling motion. As the electrons bounced off with the surrounding electrons, they emitted radiation in the extreme ultraviolet part of the spectrum. By analyzing the properties of this radiation, the researchers composed pictures that illustrate how the electron cloud is distributed among atoms in the crystal lattice of solids with a resolution of a few tens of picometers which is a billionth of a millimeter.

The experiments pave the way towards developing a new class of laser-based microscopes that could allow physicists, chemists, and material scientists to peer into the details of the microcosm with unprecedented resolution and to deeply understand and eventually control the chemical and the electronic properties of materials.

For decades scientists have used flashes of laser light to understand the inner workings of the microcosm. Such lasers flashes can now track ultrafast microscopic processes inside solids. Still they cannot spatially resolve electrons, that is, to see how electrons occupy the minute space among atoms in crystals, and how they form the chemical bonds that hold atoms together. The reason is long known. It was discovered by Abbe more than a century back. Visible light can only discern objects commensurable in size to its wavelength which is approximately few hundreds of nanometers. But to see electrons, the microscopes have to increase their magnification power by a few thousand times.

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To calculate the most stable atomic configuration, as well as estimate its hardness, the team relied on a computational method called density functional theory (DFT). DFT has been successfully used throughout chemistry and solid-state physics to predict the structure and properties of materials. Keeping track of the quantum states of all the electrons in a sample, and their interactions, is usually an intractable task. Instead, DFT uses an approximation that focuses on the final density of electrons in space orbiting the atoms. This simplifies the calculation to make it suitable for computers, while still providing very precise results.

Based on these calculations, the scientists found that the Young’s modulus, a measure of hardness, for pentadiamond is predicted to be almost 1700 GPa – compared with about 1200 GPa for conventional diamond.

“Not only is pentadiamond harder than conventional diamond, its density is much lower, equal to that of graphite,” explains co-author Professor Mina Maruyama.

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