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Diamond-based particle detector captures one-picosecond electron bursts for high-rate beam diagnostics

Physicists at UC Santa Cruz and other institutes across California and New Mexico have developed a detection system that will allow next-generation particle accelerators to better reveal fundamental biological and chemical processes, as well as advance critical areas such as materials science and energy research.

The Advanced Accelerator Diagnostics Collaboration, a group of two University of California campuses and three U.S. national laboratories, came together to solve a growing need for high-rate beam diagnostics. These accelerators will now jump from 120 pulses a second to 1 million pulses a second, straining current beam diagnostic systems. The results are now published in the journal Physical Review Accelerators and Beams.

“It really highlights the power of collaboration between universities and national laboratories,” said Bruce Schumm, the Long Family Professor of Experimental Physics. “If you took away Lawrence Berkeley Lab, if you took away Los Alamos, if you took away UC Davis, any of those, the whole thing would have fallen apart.”

How do flocking birds and schools of fish move? New research offers crystal-clear answer

Flocking birds and schools of fish are a familiar sight. While previous research has uncovered the broad dynamics driving these movements, their underlying intricacies remain a mystery. Now a study by a team of New York University mathematicians offers new insights into these phenomena. It reveals that flocks and schools behave in ways similar to a soft crystalline material, with individual birds and fish serving as “atoms” that are evenly spaced in a lattice-like formation.

The findings, reported in the journal Physical Review Fluids, offer detailed insights into the hydrodynamic and aerodynamic interactions crucial in aerospace and automotive engineering, robotics and energy harvesting.

“Our findings offer a new way to understand how animal collectives coordinate movement and respond to their environment,” says Christiana Mavroyiakoumou, a researcher at NYU’s Courant Institute School of Mathematics, Computing, and Data Science at the time of the study and now a fellow at Oxford University’s Mathematical Institute. “More specifically, lines of birds or fish behave like an elastic material with regularly spaced individuals held together by flexible, or spring-like, bonds—akin to soft crystalline substances in which atoms are arranged in an orderly, repeating pattern.”

How to train your magnet: Excitons as a new knob for magnetic control

Scientists can learn a lot about a quantum material by watching how it responds to light. In magnetic semiconductors, one especially useful messenger is the exciton: a pairing of a negatively charged electron and the positively charged “hole” it leaves behind. Until now, excitons in magnetic materials have mostly been used as reporters. They could reveal how spins were arranged or how magnetic waves moved through a material. But Cornell researchers have shown that excitons can do more than observe magnetism. They can actively steer it.

In the paper “Excitonic Spin Torque in a Magnetic Semiconductor,” published June 15 in Nature Materials, Youn Jue (Eunice) Bae, assistant professor of chemistry and chemical biology in the College of Arts and Sciences, and colleagues report that excitons created by light can exert a spin torque in the two-dimensional magnetic semiconductor chromium sulfide bromide, or CrSBr. The finding establishes excitons as a new way to control magnetic motion with light.

“Excitons have been very useful for watching what spins are doing in magnetic materials,” Bae said. “What we show here is that excitons can also act back on the spins. They are not just spectators; they can help drive the magnetic motion.”

Electrically tunable spin polarization in graphene opens path toward low-power spintronic devices

Researchers at the National Graphene Institute, in collaboration with the National University of Singapore, have shown that the magnetic behavior of electrons in graphene can be precisely controlled using electricity, revealing unusually large spin signals in a carefully engineered graphene system.

The study, published in Nature Communications, demonstrates how placing graphene close to a magnetic material can influence the spin of electrons without permanently altering graphene itself. By combining this magnetic proximity effect with graphene superlattices and operating at very low charge densities, the researchers were able to strongly tune how spins move through the material.

“This work shows that by combining graphene with nearby magnetic materials, we can gain a high level of control over electron spin using electrical signals alone,” said Dr. Daniel Burrow, from the University of Manchester. “In simple terms, we are learning how to pass information through graphene using the spin of electrons rather than their electrical charge.”

Circular polarization could cut laser backscatter in fusion experiments

Experiments at Lawrence Livermore National Laboratory’s National Ignition Facility (NIF) require breathtaking precision. Each of the 192 lasers is focused to a width of a few millimeters to enter a 3-millimeter hole at the top or bottom of a 2-centimeter (0.8-inch) gold canister known as a hohlraum.

As they enter, the beams intersect in plasma and transfer power, a process known as crossed-beam energy transfer (CBET). In designing a NIF inertial confinement fusion (ICF) experiment, scientists precisely tune the beams’ wavelengths to balance power via CBET and achieve better symmetry.

Small changes in wavelength have delivered big results—CBET is one key factor in achieving ignition on NIF. But what would be the effect of a more significant change in the laser architecture, namely its polarization state? LLNL scientists have calculated that this change would make the optics more resilient to filamentation damage.

Laser pulses set layered metals vibrating 1 trillion times per second, revealing electron-driven motion

How does light turn into motion within a metal? A team of researchers from European XFEL, the University of Potsdam and other participating institutions has shown that ultrashort optical laser pulses can trigger extremely rapid lattice vibrations in periodically layered metal structures—not primarily by heating the atomic lattice, but through the pressure exerted by hot electrons. The results are published in Nature Communications.

In the study, platinum and copper layers just a few nanometers (millionths of a millimeter) thick were stacked to form an artificial metal lattice. After being excited by a laser pulse, the artificial crystal lattice began to oscillate at around one terahertz: At a rate of roughly one trillion times per second, the platinum nanolayers expand and squeeze the copper layers. The oscillation, which begins immediately, is too rapid to be explained by conventional lattice heating via heat transfer from the electrons.

“That surprised us,” says Jan-Etienne Pudell of European XFEL. “The oscillation is not caused by the pressure of the heated lattice, but by electron pressure, particularly in the platinum layers.”

Scientists Let People Play Video Games Using Only Their Thoughts

Researchers developed a brain-controlled gaming system that learns from the brain’s natural wiring, enabling fast BCI training and potentially transforming medicine, mental health, and human-computer interaction. It may not be long before video game controllers become optional. Researchers at

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