Berkeley Lab
Bringing Science Solutions to the World

Nuclear Science Division

Raúl Briceño awarded the Presidential Early Career Award for Scientists and Engineers (PECASE)

Raúl Briceño, a faculty scientist in the Nuclear Sciences Division’s Nuclear Theory Group and an assistant professor of physics at UC Berkeley, is one of three Berkeley Lab scientists to receive the Presidential Early Career Award for Scientists and Engineers (PECASE), the highest honor bestowed by the U.S. government on outstanding scientists and engineers early in their careers.

NSD Hosts 15th Workshop on Critical Point Onset of Deconfinement (CPOD2024)

In May, NSD hosted the 15th Workshop on Critical Point and Onset of Deconfinement (CPOD2024) at LBNL.  CPOD is a series of international meetings which focus on the physics of the QCD phase structure in high-energy nuclear collisions, especially in the region of high baryon density where a possible phase transition and a critical point are conjectured to be located.

A total of 95 participants enjoyed an exciting scientific program that included experimental and theoretical topics.  Many experimental results were reported by international collaborations including ALICE at CERN, HADES at GSI, SHIAN(NA61) at SPS and STAR at BNL. The STAR experiment released the awaited new results on higher moments of the proton and anti-proton distributions from the RHIC beam energy scan phase II. The proton(anti-proton) high order correlations are believed to be sensitive to the QCD critical point. At the center of collision energy of 20 GeV, the experiment observed a 4-5sigma deviation of the data from known non-critical model calculations. The data points to the change of structure of the medium created in the heavy-ion collisions. The new results have stimulated engaged discussions during the workshop and on the internet.

Theorists also presented predictions on the location of the QCD critical point. Calculations from Lattice Gauge Theory, Functional Method, Holographic and Thermodynamic approaches were presented and, interestingly, all results point to the high baryon density regions around the baryon chemical potential of mu_B ~ 600 MeV and the temperature of T ~ 100 MeV. Recent theoretical progress regarding the inner structure of compact stars and its relation to high-energy nuclear collisions are also discussed in the meeting.NSD scientists Xin Dong, Volker Koch, Grazyna Odynier, and Nu Xu were the local organizers of the workshop.

Figure 1.  Attendees at the CPOD2024 workshop hosted at LBNL.

NSD’s Wick Haxton elected to the American Philosophical Society

The American Philosophical Society in May announced its Members elected to the Society in 2024. Election to the American Philosophical Society honors extraordinary accomplishments in all fields. The APS is unusual among learned societies because its Membership is composed of top scholars from a wide variety of academic disciplines. Wick Haxton was elected as part of the Mathematical and Physical Sciences class.

Wick C. Haxton
Distinguished Professor of Physics, University of California, Berkeley;
Senior Faculty Scientist, Lawrence Berkeley National Laboratory;
Professor Emeritus, University of Washington

Xin-Nian Wang receives 2024 Humboldt Research Award

Xin-Nian Wang, a senior scientist in the Nuclear Theory Program, has received a prestigious 2024 Humboldt Research Award.

Wang’s main research interests lie in theoretical high-energy nuclear physics to explore a new state of matter in ultra-relativistic heavy-ion collisions at the Relativistic Heavy-ion Collider (RHIC) at the Brookhaven National Lab and the Large Hadron Collider (LHC) at CERN. Quark-gluon plasma (QGP) is a state of matter that is believed to have existed in the early universe only a few microseconds after the Big Bang and is thought to currently exist at the core of some of our Universe’s compact stellar objects such as neutron stars. With fellow Berkeley Lab physicist Miklos Gyulassy, he pioneered the study of QGP properties using energetic particles referred to as “jets,” which are produced together with QGP in high-energy heavy-ion collisions. His recent work focuses on developing a technique called jet tomography, which uses jets and the supersonic sound waves they generate to shed light on the thermodynamic and transport properties of QGP. Together with their collaborators, Wang’s team also predicted the spin polarization of particles due to the vortical flow in QGP in noncentral heavy-ion collisions. This phenomenon was observed by the STAR Collaboration, revealing that the QGP in noncentral heavy-ion collisions is the most vortical fluid in nature. Wang is also interested in using jets to study the properties of cold nuclei at high energy in the future Electron-Ion Collider (EIC), to be built at the Brookhaven National Lab.

Lattice QCD Calculation of Electroweak Box Contributions to Superallowed Nuclear and Neutron Beta Decays

In a recent publication in Physical Review Letters, an international collaboration including NSD’s Keh-Fei Liu and Bi-Gebg Wang used Lattice QCD – a numerical approach that allows the theoretical exploration of the interactions between quarks and gluons – to shed new light on superallowed nuclear and neutron beta-decay.  This work reduces the theoretical uncertainty in extracting the flavor-changing weak interaction matrix element in neutron beta-decay.