Archive for the ‘particle physics’ category: Page 312

Nov 5, 2019

Space craft

Posted by in categories: particle physics, space travel

The second objective is propulsion. This is achieved by emitting pulsed cathode rays out of one end of the craft tuned to the rate of change of jet stream particles surrounding the bubble. At the other end of the craft, cations are emitted at the same rate of change. This creates a push/pull effect, doubling the ship’s acceleration and velocity capabilities.

Nov 5, 2019

Detection of a strange particle

Posted by in category: particle physics


In 1947, scientists found a previously unseen particle, which is now called a neutral kaon. This work led to the discovery of elementary particles known as quarks, and ultimately to the establishment of the standard model of particle physics. From the observation of a neutral kaon to the standard model.

Nov 5, 2019

Suspended layers make a special superconductor

Posted by in categories: materials, particle physics

In superconducting materials, an electric current will flow without any resistance. There are quite a few practical applications of this phenomenon; however, many fundamental questions remain as yet unanswered. Associate Professor Justin Ye, head of the Device Physics of Complex Materials group at the University of Groningen, studied superconductivity in a double layer of molybdenum disulfide and discovered new superconducting states. The results were published in the journal Nature Nanotechnology on 4 November.

Superconductivity has been shown in monolayer crystals of, for example, molybdenum disulphide or tungsten disulfide that have a thickness of just three atoms. “In both monolayers, there is a special type of in which an protects the from external magnetic fields,” Ye explains. Normal superconductivity disappears when a large external magnetic field is applied, but this Ising superconductivity is strongly protected. Even in the strongest static magnetic field in Europe, which has a strength of 37 Tesla, the superconductivity in tungsten disulfide does not show any change. However, although it is great to have such strong protection, the next challenge is to find a way to control this protective effect, by applying an electric field.

Nov 4, 2019

Determining the shapes of atomic clusters

Posted by in categories: mathematics, nanotechnology, particle physics, robotics/AI

Too large to be classed as molecules, but too small to be bulk solids, atomic clusters can range in size from a few dozen to several hundred atoms. The structures can be used for a diverse range of applications, which requires a detailed knowledge of their shapes. These are easy to describe using mathematics in some cases; while in others, their morphologies are far more irregular. However, current models typically ignore this level of detail; often defining clusters as simple ball-shaped structures.

In research published in The European Physical Journal B, José M. Cabrera-Trujillo and colleagues at the Autonomous University of San Luis Potosí in Mexico propose a new method of identifying the morphologies of atomic clusters. They have now confirmed that the distinctive geometric shapes of some clusters, as well as the irregularity of amorphous structures, can be fully identified mathematically.

The insights gathered by Cabrera-Trujillo’s team could make it easier for researchers to engineer atomic clusters for specific applications. These could include nanoparticles containing two different metals, which are highly effective in catalysing chemical reactions. Their updated methods provided new ways to determine the structural properties of clusters, the ways in which they convert energy to different forms, and the potential forces between atoms. The technique was also able to distinguish the surrounding environments of atoms in the cores of clusters, and on their surfaces. Ultimately, this allowed the researchers to distinguish between distinctive shapes, including icosahedrons, octahedrons, and simple pancakes. They were also able to identify amorphous shapes, which contain no discernible mathematical order.

Nov 3, 2019

Using an accurate measurement of the parameters of planetary bodies to constrain the mass of the graviton

Posted by in categories: information science, particle physics

A team of researchers affiliated with several institutions in France has revisited the idea of improving on estimates of the upper limit of the mass of a graviton. In their paper published in the journal Physical Review Letters, the group describes their accurate measurement of the parameters of planetary bodies and what they found.

Einstein’s suggests that the gravity of large masses that warps spacetime comes from a theoretical massless particle called the graviton. Scientists have been trying for many years to either prove the theory correct or disprove it by finding a way to show that it has . One approach to such a proof involves studying the speed of the expansion of the universe—this approach has suggested that if the graviton does have a mass, its upper limit would be approximately 10 −32 electron-volts. Unfortunately, this result is based on a lot of assumptions, many of which are still controversial. Another way to do it is by studying planetary orbital deviations that could only come from a nonzero graviton mass—and starting with the assumption that if a graviton has zero mass, then like the photon, it should travel at the speed of light. In this new effort, the researchers have found a way to improve the accuracy of this approach.

The work involved temporarily freezing the motion of the stars and planets at different points in time—the first was the year 2000. The researchers found the masses, positions and speed of the sun, the planets and several asteroids for that year. They then ran equations that allowed them to roll forward in time to 2017 and back to 1913 and forward again as needed. These time periods were chosen because the team was able to find usable data for them. In running the calculations, the researchers found that they were able to come up with an estimation for the upper limit of the graviton of 6.76 × 10 −23—with a probability of 90 percent. The researchers note that their number was very close to that found by a team using data from the LIGO interferometers, but suggest that any similarities were purely coincidence.

Nov 1, 2019

Sean Carroll: Quantum Mechanics and the Many-Worlds Interpretation

Posted by in categories: cosmology, mathematics, particle physics, quantum physics, robotics/AI, space travel, time travel

Sean Carroll is a theoretical physicist at Caltech and Santa Fe Institute specializing in quantum mechanics, arrow of time, cosmology, and gravitation. He is the author of several popular books including his latest on quantum mechanics (Something Deeply Hidden) and is a host of a great podcast called Mindscape. This conversation is part of the Artificial Intelligence podcast.

This is the second time Sean has been on the podcast. You can watch the first time here:

Continue reading “Sean Carroll: Quantum Mechanics and the Many-Worlds Interpretation” »

Oct 31, 2019

Evading Heisenberg isn’t easy

Posted by in categories: particle physics, quantum physics

EPFL researchers, with colleagues at the University of Cambridge and IBM Research-Zurich, unravel novel dynamics in the interaction between light and mechanical motion with significant implications for quantum measurements designed to evade the influence of the detector in the notorious ‘back action limit’ problem.

The limits of classical measurements of mechanical motion have been pushed beyond expectations in recent years, e.g. in the first direct observation of , which were manifested as tiny displacements of mirrors in kilometer-scale optical interferometers. On the microscopic scale, atomic- and magnetic-resonance force microscopes can now reveal the atomic structure of materials and even sense the spins of single atoms.

But the that we can achieve using purely conventional means is limited. For example, Heisenberg’s uncertainty principle in implies the presence of “measurement backaction”: the exact knowledge of the location of a particle invariably destroys any knowledge of its momentum, and thus of predicting any of its future locations.

Oct 30, 2019

US dark-matter detector heads underground

Posted by in category: particle physics

The main component of the LUX-ZEPLIN dark-matter detector has been installed at the Sanford Underground Research Facility in Lead, South Dakota.

The central cryostat for the experiment, which weighs about 2200 kg, was successfully lowered some 1500 m underground last week. Over the coming months, the detector will be wrapped in layers of insulation and then next year be filled with around 10 tonnes of ultra-pure liquid xenon.

LUX-ZEPLIN is expected to begin operation in July 2020 when it will become the largest direct detection dark-matter experiment in the US. It will search for weakly interacting massive particles – a leading dark-matter candidate – with scientists hoping to capture flashes of light that are produced when dark-matter particles interact with the heavy xenon atoms.

Oct 30, 2019

Is a New Particle Changing the Fate of the Universe?

Posted by in categories: particle physics, space

A brand-new particle has possibly emerged and is altering the future destiny of our entire cosmos, a physicist says.

Oct 30, 2019

Dielectric metasurfaces for next-generation holograms

Posted by in categories: computing, holograms, information science, nanotechnology, particle physics, transportation

Metasurfaces are optically thin metamaterials that can control the wavefront of light completely, although they are primarily used to control the phase of light. In a new report, Adam C. Overvig and colleagues in the departments of Applied Physics and Applied Mathematics at the Columbia University and the Center for Functional Nanomaterials at the Brookhaven National Laboratory in New York, U.S., presented a novel study approach, now published on Light: Science & Applications. The simple concept used meta-atoms with a varying degree of form birefringence and angles of rotation to create high-efficiency dielectric metasurfaces with ability to control optical amplitude (maximum extent of a vibration) and phase at one or two frequencies. The work opened applications in computer-generated holography to faithfully reproduce the phase and amplitude of a target holographic scene without using iterative algorithms that are typically required during phase-only holography.

The team demonstrated all-dielectric holograms with independent and complete control of the amplitude and phase. They used two simultaneous optical frequencies to generate two-dimensional (2-D) and 3D holograms in the study. The phase-amplitude metasurfaces allowed additional features that could not be attained with phase-only holography. The features included artifact-free 2-D holograms, the ability to encode separate phase and amplitude profiles at the object plane and encode intensity profiles at the metasurface and object planes separately. Using the method, the scientists also controlled the surface textures of 3D holographic objects.

Light waves possess four key properties including amplitude, phase, polarization and optical impedance. Materials scientists use metamaterials or “metasurfaces” to tune these properties at specific frequencies with subwavelength, spatial resolution. Researchers can also engineer individual structures or “meta-atoms” to facilitate a variety of optical functionalities. Device functionality is presently limited by the ability to control and integrate all four properties of light independently in the lab. Setbacks include challenges of developing individual meta-atoms with varying responses at a desired frequency with a single fabrication protocol. Research studies previously used metallic scatterers due to their strong light-matter interactions to eliminate inherent optical losses relative to metals while using lossless dielectric platforms for high-efficiency phase control—the single most important property for wavefront control.