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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.

Data scientists and developers at Jefferson Lab are exploring some of the latest artificial intelligence techniques to help make high-performance computers more reliable and less costly to run. The study deploys machine learning models that are trained to monitor and predict the behavior of a scientific computing cluster. The goal is to help system administrators quickly identify and respond to troublesome computing jobs or hardware behavior, reducing downtime for scientists processing data from their experiments.

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.

Jefferson Lab’s heating, ventilation and air conditioning professionals ensure optimal operation of operational and scientific facilities through their technical expertise.

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.

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.

The year 2025 has been proclaimed the International Year of Quantum Science and Technology by the United Nations, recognizing 100 years since the initial development of quantum mechanics. Now, Jefferson Lab, MIT and Sputnik Animation unveil “Visualizing the Nucleus,” a new animation of the particles and forces that dominate the quantum world and an accompanying website exhibit featuring the visualization of the structure of matter throughout history.

For nearly half a century, Robert D. “Bob” McKeown has probed nuclear particles and educated rising generations of physicists. Now, the former deputy director for science at the U.S. Department of Energy’s Thomas Jefferson National Accelerator Facility is being honored for his outstanding career contributions with the 2024 American Physical Society’s Division of Nuclear Physics (DNP) Distinguished Service Award.

Jefferson Lab announces its newest slate of projects to receive Laboratory Directed Research & Development (LDRD) program funding for 2025. In its 12th year, the LDRD program will split $3 million among 13 different projects.