News By Location

The nuclear reactions that power stellar explosions involve short-lived nuclei that are hard to study in the laboratory. Researchers used a combination of methods to measure a reaction where a neutron from a deuterium target is exchanged with a proton from a radioactive projectile, a reaction equivalent to a process in exploding stars. The results shed light on how stellar explosions shape the universe and the elements.

Researchers have discovered a way to tune some semiconductors to reduce the amount of energy needed to eject electrons. The approach works by placing a bilayer coating of an insulator and graphene on top of the semiconductor then applying a voltage between the semiconductor and graphene. This bilayer approach could improve the efficiency of electromechanical devices and electron accelerators.

For the first time, scientists have direct evidence of an exotic state of ice that may form inside Uranus, Neptune, and other water-rich gas giants due to extreme temperatures and pressures. The research shows that this phase, Ice XIX, has oxygen atoms packed in a body-centered cubic structure but hydrogen atoms that move freely like a fluid, increasing electrical conductivity. This may explain Voyager II’s observations of these planets’ magnetic fields.

Researchers mapped the locations of 1,034 proteins inside the chloroplast of the unicellular green alga Chlamydomonas. This map is a spatial atlas of the chloroplast proteome—all of the proteins that the organism can produce in the algae’s structure that drives photosynthesis. The results will help scientists advance their understanding of the chloroplast function, enabling them to  design bioenergy crops with improved photosynthetic capacity.

Using a combination of experimental facilities, researchers directly measured a key reaction that takes place in the explosions on the surfaces of neutron stars. This is the first-ever measurement of this reaction. Contrary to expectation, the experimental data agreed with predictions from a common theoretical model used to calculate reaction rates.

When a muon binds with a deuteron, it forms a system with two neutrons in a process analogous to proton-proton fusion. Nuclear theorists examined this muon capture process to quantify theoretical uncertainty relevant for comparison with experimental data and to test predictions involving proton-proton fusion. The study supports ongoing efforts to enhance the accuracy of muon capture measurements and to apply the same theoretical framework to other processes.

Theorists have successfully calculated the “heavy quark diffusion coefficient,” which describes how quickly a melted soup of quarks and gluons transfers its momentum to heavy quarks. The results show this transfer is very fast—at the limit of what quantum mechanics will allow. The calculations show that the quarks and gluons liberated in these collisions have so many short-range, strong interactions with the heavier quarks that they pull the boulder-like particles along.