Lifeboat Foundation

Adjusting experimental methods achieved the first “single-shot” diagnosis of electron acceleration through a laser wakefield accelerator along a curved trajectory, according to a recent study led by University of Michigan researchers. The findings are published in the journal Physical Review Letters.

This optical-based technique could help engineers develop more powerful electron accelerators for fundamental studies of quantum and particle physics —or more compact accelerators for use in medicine and industry.

Compared to traditional accelerators which can be kilometers long, laser wakefield accelerators can apply 1,000 times more energy per meter, allowing a vastly more compact design able to fit into a large room.

Scientists at the University of Konstanz in Germany have advanced ultrafast electron microscopy to unprecedented time resolution. Reporting in Science Advances, the research team presents a method for the all-optical control, compression, and characterization of electron pulses within a transmission electron microscope using terahertz light. Additionally, the researchers have discovered substantial anti-correlations in the time domain for two-electron and three-electron states, providing deeper insight into the quantum physics of free electrons.

Ultrafast electron microscopy is a cutting-edge technique that combines the spatial resolution of traditional electron microscopy with the temporal resolution of ultrafast femtosecond laser pulses. This powerful combination allows researchers to observe atoms and electrons in motion, capturing dynamic processes in materials with unparalleled clarity. By visualizing these rapid events in space and time, scientists can gain deeper insights into the fundamental mechanisms that govern material properties and transitions, helping to create advancements in research fields such as nanotechnology, optics, materials science, and quantum physics.

Although ultrafast electron microscopy enables, in principle, the observation of atomic and electronic motions on fundamental spatial and temporal scales, capturing these rapid dynamics has remained challenging due to the limitations in electron pulse duration. The current standard electron pulses, lasting about 200 femtoseconds, are too long to resolve many fundamental reaction processes in materials and molecules. Pulses ten times shorter would be required to observe basic reaction paths and collective atomic motions, so-called phonon modes, in real time.

During electron-impact ionization (EII), high-energy electrons collide with atoms, knocking away one or more of their outer electrons. To calculate the probability that ionization will occur during these impacts, researchers use a quantity named the “ionization cross-section.” EII is among the main processes affecting the balance of charges in hot plasma, but so far, its cross-section has proven incredibly difficult to study through theoretical calculations.

Through new research published in The European Physical Journal D, Stefan Schippers and colleagues at Justus-Liebig University of Giessen, Germany, present new calculations for the EII cross-section, which closely match with their experimental results. Their discoveries could provide useful new insights in many fields of research where hot plasma is studied, including astrophysics and controlled nuclear fusion.

So far, EII cross-sections have proven especially challenging to calculate for two key reasons: the complex interactions that can emerge between the electrons involved in the process, and the wide array of possible electron configurations in the atoms being impacted.

As lasers go, those made of Titanium-sapphire (Ti: sapphire) are considered to have “unmatched” performance. They are indispensable in many fields, including cutting-edge quantum optics, spectroscopy, and neuroscience. But that performance comes at a steep price. Ti: sapphire lasers are big, on the order of cubic feet in volume. They are expensive, costing hundreds of thousands of dollars each. And they require other high-powered lasers, themselves costing $30,000 each, to supply them with enough energy to function.

As a result, Ti:sapphire lasers have never achieved the broad, real-world adoption they deserve—until now. In a dramatic leap forward in scale, efficiency, and cost, researchers at Stanford University have built a Ti: sapphire laser on a chip. The prototype is four orders of magnitude smaller (10,000x) and three orders less expensive (1,000x) than any Ti: sapphire laser ever produced.

“This is a complete departure from the old model,” said Jelena Vučković, the Jensen Huang Professor in Global Leadership, a professor of electrical engineering, and senior author of the paper introducing the chip-scale Ti: sapphire laser published in the journal Nature.

Abstract We have analytically determined the refractive index for the mechanical refraction of a relativistic particle for its all possible speeds. We have critically analysed the importance of Descartes’ metaphysical theory and extended it in this regard. We have considered the conservation of the tangential component of the relativistic momentum and the relativistic energy of the particle in the process of the mechanical refraction within the optical-mechanical analogy. Our result for the mechanical refractive index exactly matches with the forms of both the Fermat’s result on Snell’s law of optical refraction at the ultra-relativistic limit and the Descartes’ metaphysical result on the pseudo-Snell law of optical refraction at the non-relativistic limit. Graphic abstract Mechanical refraction from medium-1 to medium-2 for $$U2U1$$ U 2 U 1.

An international joint research team led by the Photonic Network Laboratory of Japan’s National Institute of Information and Communications Technology (NICT) has demonstrated a record-breaking aggregate optical transmission bandwidth of 37.6 THz to enable a new data-rate record of 402 terabits per second in a standard commercially available optical fiber.

This record was achieved by constructing the first optical transmission system covering all the transmission bands (OESCLU) of the low-loss window of standard optical fibers. The system combined various amplification technologies, some developed for this demonstration, including six kinds of doped fiber optical amplifiers and both discrete and distributed Raman amplification.

Novel optical gain equalizers also allowed access to new wavelength bands that are not yet utilized in deployed systems. The newly developed technology is expected to make a significant contribution to expanding the communication capacity of the optical communication infrastructure as future data services rapidly increase demand.

Most of us are familiar with the classic example of a liquid-gas moving contact line on a solid surface: a raindrop, sheared by the wind, creeps along a glass windscreen. The contact line’s movements depend on the interplay between viscous and surface tension forces—a relationship that has been thoroughly investigated in experimental fluid mechanics.

In a study published in The European Physical Journal Special Topics, Harish Dixit, of the Indian Institute of Technology Hyderabad, and his colleagues now examine the movements of a contact line formed at the interface between two immiscible liquids and a solid. The experiments fill a gap in fluid dynamics and suggest a mechanism for an imposed boundary condition that eludes mathematical description.

According to theory, the movement of a liquid-liquid contact line should be governed entirely by the liquids’ viscosity ratio and the angle at which the liquid interface meets the solid. To examine this in a real-world system, Dixit and his colleagues filled a rectangular tank with two liquid layers—silicone oil atop sugar water—with similar densities but significantly different viscosities. The researchers placed a glass slide at the edge of the tank, which they could slide vertically to create a moving contact line.

Advanced Materials, one of the world’s most prestigious journals, is the home of choice for best-in-class materials science for more than 30 years.

Two asteroids, including the newly detected 2024 MK, will pass Earth safely this week, coinciding with Asteroid Day. The event highlights efforts such as ESA’s asteroid deflection mission and their new Flyeye telescope system aimed at improving our detection and response to these celestial threats.

Two large asteroids will safely pass Earth this week, a rare occurrence perfectly timed to commemorate this year’s Asteroid Day. Neither poses any risk to our planet, but one of them was only discovered a week ago, highlighting the need to continue improving our ability to detect potentially hazardous objects in our cosmic neighborhood.