AbstractAlpha particles with energies on the order of megaelectronvolts will be the main source of plasma heating in future magnetic confinement fusion react… See more.
Experiments at the Joint European Torus tokamak show improved thermal ion confinement in the presence of highly energetic ions and Alfvénic instabilities in the plasma.
An investigation into a neutron-rich isotope of indium using a cutting-edge nuclear physics technique has begun to unravel the mysteries of how single particles behave inside the nucleus.
We have known that a nucleus is comprised of protons, which give an element its atomic number, and neutrons since the early 1930s. But how an individual proton or neutron behaves inside the heart of an atom is still poorly understood. Now, an international collaboration including scientists from Canada, China, Finland, France, Germany, Poland, Sweden, Switzerland, the UK and US has taken a step closer to understanding these complex interactions.
Nuclear physics researchers often look at elements with so-called ‘magic numbers’ of protons or neutrons, which are exceptionally well bound and thus highly stable. However, to learn about nuclear structure, nuclides with one fewer proton are used, known as a single proton hole. By investigating the electronic transitions, researchers can study the atomic, hyperfine structure of individual particles due to the interactions between electrons and the nucleus. This gives clues as to the nucleus’ magnetic and electric characteristics, which can then give a complete picture of how all protons and neutrons are distributed and interact inside a nucleus.
How did the Arava, a punishingly hot and arid desert, become one of Israel’s breadbaskets? It’s a story of determination and thinking outside the box.
The discovery could inform the design of practical superconducting devices. When it comes to graphene, it appears that superconductivity runs in the family. Graphene is a single-atom-thin 2D material that can be produced by exfoliation from the same graphite that is found in pencil lead. The u.
The discovery could inform the design of practical superconducting devices.
When it comes to graphene.
Graphene is an allotrope of carbon in the form of a single layer of atoms in a two-dimensional hexagonal lattice in which one atom forms each vertex. It is the basic structural element of other allotropes of carbon, including graphite, charcoal, carbon nanotubes, and fullerenes. In proportion to its thickness, it is about 100 times stronger than the strongest steel.
The sterile neutrino, if it truly exists, only answers to gravity.
Physicists are spelunking the complex findings from an experimental particle reactor found a mile below the surface in the mountains of Russia. What they found has the potential to send an earthquake through the bedrock of the standard model of physics itself: the results could confirm a new elementary particle, called a “sterile neutrino,” or demonstrate a need to revise a portion of the standard model.
The research comes from New Mexico’s Los Alamos National Laboratory in collaboration with the Baksan Neutrino Observatory near the Georgia border in far southwestern Russia. The scientists outlined their findings in two new papers published last month in the journals Physical Review Letters and Physical Review C.
To understand the team’s findings, we need to talk about neutrinos, the most common and least massive of the massive particles (the particles that have any mass at all). They were first theorized decades ago and only interact through gravity and the “weak force” of the standard model of physics, which means that, like dark matter, neutrinos can just pass through us and our planet and space however they want; they interact with almost nothing. Over the decades, scientists have developed ways to measure neutrinos by tracing their effect on what’s around them.
Ten years ago this week, two international collaborations of groups of scientists, including a large contingent from Caltech, confirmed that they had found conclusive evidence for the Higgs boson, an elusive elementary particle, first predicted in a series of articles published in the mid-1960s, that is thought to endow elementary particles with mass.
Fifty years prior, as theoretical physicists endeavored to understand the so-called electroweak theory, which describes both electromagnetism and the weak nuclear force (involved in radioactive decay), it became apparent to Peter Higgs, working in the UK, and independently to François Englert and Robert Brout, in Belgium, as well as U.S. physicist Gerald Guralnik and others, that a previously unidentified field that filled the universe was required to explain the behavior of the elementary particles that compose matter. This field, the Higgs field, would lead to a particle with zero spin, significant mass, and have the ability to spontaneously break the symmetry of the earliest universe, allowing the universe to materialize. That particle became known as the Higgs boson.
Over the decades that followed, experimental physicists first devised and then developed the instruments and methods required to detect the Higgs boson. The most ambitious of these projects was the Large Hadron Collider (LHC), which is operated by the European Organization for Nuclear Research, or CERN. Since the planning of the LHC in the late 1980s, the U.S. Department of Energy and the National Science Foundation have worked in collaboration with CERN to provide funding and technology know-how, and to support thousands of scientists helping to search for the Higgs.
Scientists at Tokyo Institute of Technology designed a new type of molecular wire doped with organometallic ruthenium to achieve unprecedentedly higher conductance than earlier molecular wires. The origin of high conductance in these wires is fundamentally different from similar molecular devices and suggests a potential strategy for developing highly conducting “doped” molecular wires.
Since their conception, researchers have tried to shrink electronic devices to unprecedented sizes, even to the point of fabricating them from a few molecules. Molecular wires are among the building blocks of such minuscule contraptions, and many researchers have been developing strategies to synthesize highly conductive, stable wires from carefully designed molecules.
A team of researchers from Tokyo Institute of Technology, including Yuya Tanaka, designed a novel molecular wire in the form of a metal electrode-molecule-metal electrode (MMM) junction including a polyyne, an organic chain-like molecule, “doped” with a ruthenium-based unit Ru(dppe)2. The proposed design, featured in the cover of the Journal of the American Chemical Society, is based on engineering the energy levels of the conducting orbitals of the atoms of the wire, considering the characteristics of gold electrodes.
A major goal in the field of molecular electronics, which aims to use single molecules as electronic components, is to make a device where a quantized, controllable flow of charge can be achieved at room temperature. A first step in this field is for researchers to demonstrate that single molecules can function as reproducible circuit elements such as transistors or diodes that can easily operate at room temperature.
A team led by Latha Venkataraman, professor of applied physics and chemistry at Columbia Engineering and Xavier Roy, assistant professor of chemistry (Arts & Sciences), published a study in Nature Nanotechnology that is the first to reproducibly demonstrate current blockade—the ability to switch a device from the insulating to the conducting state where charge is added and removed one electron at a time—using atomically precise molecular clusters at room temperature.
Bonnie Choi, a graduate student in the Roy group and co-lead author of the work, created a single cluster of geometrically ordered atoms with an inorganic core made of just 14 atoms—resulting in a diameter of about 0.5 nanometers—and positioned linkers that wired the core to two gold electrodes, much as a resistor is soldered to two metal electrodes to form a macroscopic electrical circuit (e.g. the filament in a light bulb).
The ability to turn superconductivity off and on with a literal flip of a switch in so-called “magic-angle twisted graphene” has allowed engineers at Caltech to observe an unusual phenomenon that may shed new light on superconductivity in general.
The research, led by Stevan Nadj-Perge, assistant professor of applied physics and materials science, was published in the journal Nature on June 15.
Magic-angle twisted graphene, first discovered in 2018, is made from two or three sheets of graphene (a form of carbon consisting of a single layer of atoms in a honeycomb-like lattice pattern) layered atop one another, with each sheet twisted at precisely 1.05 degrees in relation to the one below it. The resulting bilayer or trilayer has unusual electronic properties: for example, it can be made into an insulator or a superconductor depending on how many electrons are added.