Science Highlights

Two experiment collaborations, the g2p and EG4 collaborations, combined their complementary data on the proton’s inner structure to improve calculations of a phenomenon in atomic physics known as the hyperfine splitting of hydrogen. An atom of hydrogen is made up of an electron orbiting a proton. The overall energy level of hydrogen depends on the spin orientation of the proton and electron. If one is up and one is down, the atom will be in its lowest energy state. But if the spins of these particles are the same, the energy level of the atom will increase by a small, or hyperfine, amount. These spin-born differences in the energy level of an atom are known as hyperfine splitting.

An early-career physicist mathematically connects timelike and spacelike form factors, opening the door to further insights into the inner workings of the strong force. A new lattice QCD calculation connects two seemingly disparate reactions involving the pion, the lightest particle governed by the strong interaction. One reaction is known as the spacelike process, where an electron is bounced off a pion. The second reaction, known as the timelike process, is when an electron and antielectron collide, annihilate each other, and produce two pions. The lattice QCD numerical calculation is simultaneously able to describe the spacelike and timelike processes, demonstrating the interconnectedness of different reactions described by QCD. While this connection had been observed experimentally, now physicists have the math to corroborate it.

Quantum information scientists at the Department of Energy’s Oak Ridge National Laboratory successfully demonstrated a device that combines key quantum photonic capabilities on a single chip for the first time.

Researchers have been working for decades to understand the details of where the proton gets its intrinsic angular momentum, otherwise referred to as its spin. Recently, there have been indications that the spin contribution of the gluons could either be positive or negative. Now, a new approach that avoids assumptions and re-analyzes observational data with lattice quantum chromodynamics points strongly toward a positive gluon spin contribution, ∆g, to the proton spin.

Researchers at Argonne have discovered that superconducting nanowire photon detectors can also be used as highly accurate particle detectors, and they have found the optimal nanowire size for high detection efficiency.

Physicists know from previous experiments that what happens at the nuclear scale to protons and neutrons also affects their constituent quarks and gluons. A novel new framework has tapped on short-range correlations – brief pairings of protons and neutrons - to decipher the particles’ choreography and reveal this connection.

New studies have found that using louvers at the bottom of a fusion device creates local conditions that can reduce the temperature of the edge plasma, ensuring the plasma is not hot enough to damage the device. Specifically, the louvers allow the hot plasma to “detach” from the walls of the device, spreading out the heat. The work, on the SPARC machine, aids in progress toward fusion energy production.