High Energy Density Physics

We are involved in developing a strategy for NIF as a national HED Science user facility.

Our HEDP research comprises four groups dedicated to theoretical and experimental research in high energy density (HED) physics, astrophysics, and advanced diagnostic development, emphasizing areas important to major Laboratory programs. These groups pursue forefront research directed towards the development of experimentally validated models that describe the state of matter and the physics of matter/radiation interactions in high energy density plasmas, which contributes to our fundamental understanding of nuclear weapons, fusion plasmas, astrophysics, and planetary science. To advance HED research, enhance interactions with the international research community, and provide venues for training new scientists, we operate two intermediate scale facilities, the Jupiter Laser Facility and the Electron Beam Ion Trap.

Research Areas

The Astrophysics Group

The Electron Beam Ion Trap (EBIT)

The OPAL Opacity Code

The Radiative Properties Group

The Shock Physics Group

The Theory and Modeling Group

 
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Physicist Hui Chen sets up targets for the anti-matter experiment at the Jupiter laser facility.

LLNL Research on Positron Production from Short-pulse Laser Light

PLS researcher Hui Chen and her colleagues, S.C. Wilks, E. Liang, J. Myatt, K. Cone, L. Elberson, D.D. Meyerhofer, M. Schneider, R. Shepherd, D. Stafford, R. Tommasini, and P. Beiersdorfer, recently demonstrated experimentally the creation of a significant number of positrons from short-pulse laser light interacting with a gold target at the . The experiments were carried out using petawatt-class Titan short pulse/long pulse laser at LLNL's Jupiter Laser Facility (http://jlf.llnl.gov). The findings were reported at the American Physical Society's Division of Plasma Physics 2008 annual meeting (Nov 17 - 21) held in Dallas, TX.

We've detected far more anti-matter than anyone else has ever measured in a laser experiment," said Hui Chen, a Livermore researcher who led the experiment. "We've demonstrated the creation of a significant number of positrons using a short-pulse laser." Chen and her colleagues used a short, ultra-intense laser to irradiate a millimeter-thick gold target. "Previously, we concentrated on making positrons using paper-thin targets," said Scott Wilks, who designed and modeled the experiment using computer codes. "But recent simulations showed that millimeter-thick gold would produce far more positrons. We were very excited to see so many of them." "By creating this much anti-matter, we can study in more detail whether anti-matter really is just like matter, and perhaps gain more clues as to why the universe we see has more matter than anti-matter," said Peter Beiersdorfer, a lead Livermore physicist working with Chen.

Over the years, physicists have theorized about anti-matter, but it wasn't confirmed to exist experimentally until 1932. High-energy cosmic rays impacting Earth's atmosphere produce minute quantities of anti-matter in the resulting jets, and physicists have learned to produce modest amounts of anti-matter using traditional particle accelerators. Laser production of anti-matter isn't entirely new either. Livermore researchers detected anti-matter about 10 years ago in experiments on the since-decommissioned Nova "petawatt" laser - about 100 particles. But with a better target and a more sensitive detector, this year's experiments directly detected more than 1 million particles. From that sample, the scientists infer that around 100 billion positron particles were produced in total.