The Large Hadron Collider (LHC), a 17-mile particle accelerator buried under the French-Swiss border, has achieved the centuries-old dream of alchemists: transforming lead into gold. However, this accomplishment was not without its limitations – it happened within a fraction of a second. The scientists reported their results in Physical Reviews.

The achievement was made possible by the sophisticated and sensitive detector called ALICE, which is roughly the size of a McMansion. It was scientists from the University of Kansas, working on the ALICE experiment, who developed the technique that tracked “ultra-peripheral” collisions between protons and ions that resulted in gold creation at the LHC.

According to Daniel Tapia Takaki, professor of physics and leader of KU’s group at ALICE, these ultra-peripheral collisions involve near misses between particles. The ions racing around the LHC tunnel are heavy nuclei with many protons, each generating powerful electric fields. When accelerated, these charged ions emit photons – they shine light.

“When you accelerate an electric charge to near light speeds, it starts shining,” Tapia Takaki said. “One ion can shine light that essentially takes a picture of the other. When that light is energetic enough, it can probe deep inside the other nucleus, like a high-energy flashbulb.”

During these ultra-peripheral collisions, surprising interactions can occur, including the creation of gold through photon-photon collisions. These events are incredibly clean, with almost nothing else produced. They contrast with typical collisions where sprays of particles flying everywhere.

However, the ALICE detector and the LHC were designed to collect data on head-on collisions that result in messy sprays of particles. These clean interactions were hard to detect with earlier setups.

Tapia Takaki’s KU co-authors on the paper are graduate student Anna Binoy; graduate student Amrit Gautam; postdoctoral researcher Tommaso Isidori; postdoctoral research assistant Anisa Khatun; and research scientist Nicola Minafra. The KU team at the LHC ALICE experiment plans to continue studying the ultra-peripheral collisions.

Tapia Takaki said that while the creation of gold fascinated the public, the potential of understanding the interactions goes deeper. This light is so energetic, it can knock protons out of the nucleus, sometimes one, sometimes two, three or even four protons. We can see these ejected protons directly with our detectors.

Each proton removed changes the elements: One gives thallium, two gives mercury, three gives gold. These new nuclei are very short-lived, they decay quickly, but not always immediately. Sometimes they travel along the beamline and hit parts of the collider – triggering safety systems.

That’s why this research matters beyond the headlines. With proposals for future colliders even larger than the LHC – some up to 100 kilometers in Europe and China – you need to understand these nuclear byproducts. This ‘alchemy’ may be crucial for designing the next generation of machines.

This work was supported by the U.S. Department of Energy Office of Science, Office of Nuclear Physics.

As scientists continue to push the boundaries of what is possible, they stumble upon unexpected discoveries that challenge our understanding of the world. A recent breakthrough at the SLAC National Accelerator Laboratory has revealed the secret chemistry of gold, a metal once thought to be unreactive and boring. Researchers have successfully formed solid binary gold hydride, a compound made exclusively of gold and hydrogen atoms, under extreme conditions.

The team led by Mungo Frost, staff scientist at SLAC, was studying how hydrocarbons form diamonds under high pressure and heat. In their experiments at the European XFEL in Germany, they embedded gold foil into the samples to absorb X-rays and heat the weakly absorbing hydrocarbons. To their surprise, they not only observed the formation of diamonds but also discovered the formation of gold hydride.

“It was unexpected because gold is typically chemically very boring and unreactive — that’s why we use it as an X-ray absorber in these experiments,” said Mungo Frost. “These results suggest there’s potentially a lot of new chemistry to be discovered at extreme conditions where the effects of temperature and pressure start competing with conventional chemistry, and you can form these exotic compounds.”

The research team used a diamond anvil cell to squeeze hydrocarbon samples to pressures greater than those within Earth’s mantle and then heated them to over 3,500 degrees Fahrenheit using X-ray pulses from the European XFEL. This allowed them to resolve the structural transformations within the samples and observe how the gold lattice scattered X-rays.

The team found that under these extreme conditions, hydrogen was in a dense, superionic state, flowing freely through the gold’s rigid atomic lattice and increasing its conductivity. This phenomenon is not directly accessible through other experimental means, but studying it could provide new insights into nuclear fusion processes inside stars like our sun and help develop technology to harness fusion energy on Earth.

The discovery of gold hydride also opens up new avenues for exploring chemistry at extreme conditions. Gold, once thought to be unreactive, was found to form a stable compound with hydrogen under high pressure and temperature. This suggests that more research is needed to understand the properties of materials under these extreme conditions.

In addition to their findings on gold hydride, the team also developed simulation tools that could model other exotic material properties in extreme conditions. These tools have the potential to be applied beyond this specific study, offering new opportunities for researchers to explore and understand complex phenomena.

The research was conducted by an international team of scientists from SLAC National Accelerator Laboratory, European XFEL, DESY, Rostock University, Frankfurt University, Bayreuth University, Carnegie Institution for Science, Stanford University, and the Stanford Institute for Materials and Energy Sciences (SIMES). The work was supported by the DOE Office of Science.

The article begins by highlighting the pressing issue of petroleum-derived plastic pollution and the detrimental effects of microplastics on our food and water supplies. In response to this problem, researchers have been developing biodegradable versions of traditional plastics, or “bioplastics.” However, current bioplastics face challenges as they are not as strong as petrochemical-based plastics and only degrade through a high-temperature composting system.

Enter researchers at Washington University in St. Louis, who have solved both problems with inspiration from the humble leaf. The team decided to introduce cellulose nanofibers to the design of bioplastics, creating a multilayer structure where cellulose is in the middle and the bioplastics are on two sides. This unique biomimicking design allows for broader bioplastic utilization, addressing the limitations of current versions.

The researchers emerged from working with two high-production bioplastics today: polyhydroxybutrate (PHB) and polylactic acid (PLA). They used a variation of their leaf-inspired cellulose nanofiber structure to improve the strength and biodegradability of these plastics. The optimized bioplastic, called Layered, Ecological, Advanced and multi-Functional Film (LEAFF), turned PLA into a packaging material that is biodegradable at room temperature.

The researchers’ innovation was in adding the cellulosic structure that replicates cellulose fibrils embedded within the bioplastics. This unique design allows for critical properties such as low air or water permeability, helping keep food stable, and a surface that is printable. Additionally, the LEAFF’s underlying cellulose structure gives it a higher tensile strength than even petrochemical plastics like polyethylene and polypropylene.

The researchers hope this technology can scale up soon and seek commercial and philanthropic partners to help bring these improved processes to industry. They believe the United States is uniquely positioned to dominate the bioplastics market and establish a “circular economy” wherein waste products are reused, fed back into systems instead of left to pollute the air and water or sit in landfills.

The article concludes by highlighting the potential for the U.S. to create jobs and new markets through the development and implementation of this sustainable technology. The researchers also emphasize the importance of circular reuse in turning waste into useful materials.