LLNL physicists, chemists, and engineers leverage powerful tools in the accelerator complex to address evolving national security challenges.
Nuclear physics research at LLNL encompasses a broad range of experimental capabilities, where researchers study subatomic particles that play a key role in our national security mission. LLNL’s investigators design, test, and refine new tools that enable them to detect isotopes; explore the structure of unstable nuclei; confine and measure radioactive ions; analyze fission reactions; and understand neutron scattering.
Our teams continue expanding and enhancing our suite of world-class instruments, offering new research opportunities at the frontier of nuclear and particle physics.
Our neutron imaging system is based on a deuterium-deuterium fusion reaction, where fast neutrons are produced through deuteron bombardment. The radiographic technique is used to penetrate thick, dense objects and produce images of interior features—offering a robust, non-destructive evaluation tool.
In addition, the system’s neutron source capability plays a key role in research involving nuclear cross-section measurements, material assay via gamma-ray spectroscopy, and studies of radiation effects on material performance.
The state-of-the-art, fast neutron source includes two deuteron ion accelerators, a fully instrumented beamline, an advanced optics system, and high-power neutron production targets. It fits in a 5,000-square-foot space and offers powerful, sub-millimeter radiographic imaging.
LLNL’s Photonuclear Reactions for Isotopic Signature Measurements (PRISM) accelerator provides unique experimental capabilities in experimental nuclear physics, accelerator physics, detector development, and nuclear reaction modeling. Coupled with a bremsstrahlung converter, PRISM operates as a high-energy, high-intensity photon source for a range of applications. In support of stockpile stewardship and national security missions, LLNL scientists can use the PRISM system to measure photo-nuclear cross sections and infer quantities of interest for a variety of nuclear materials. The system’s flexibility for measurements at lower energies supports important physics research that addresses both programmatic and fundamental science needs.
PRISM generates high-energy x-rays, which then interact with nuclei. Detectors measure particles generated by the neutron-induced reactions. For example, PRISM’s photofission-based neutron source can be used to:
PRISM can accelerate electrons up to 25 MeV. However, by tuning the accelerator to low-electron energy, it can also be used to study radiation effects, support radiochemistry research, or analyze medical isotope production.
MEGa-ray is a state-of-the-art electron accelerator developed as a Laser-Compton light source using a high-gradient X-band, photoinjector-based accelerator. Originally used for Laser-Compton experiments and related research, LLNL scientists adapted the technology to support a broader range of physics research and applications.
The system begins with short, picosecond laser pulses that produce short electron bunches on the photocathode, with the X-band accelerator boosting the energy of the electrons. These highly energetic electron bunches collide with separate laser photons, which gain energy from their Compton-scattering interaction. This scattered x-ray radiation is Doppler upshifted in energy and directed forward in a narrow-bandwidth photon beam.
The light source can be tuned to different wavelengths so that it predominantly interacts with only one kind of material—in a process known as isotope-specific nuclear photonics. The beam can penetrate through lead and other thick containers, enabling researchers to non-destructively detect, image, and assay specific objects of interest, such as nuclear waste canisters, nuclear fuel rods, and other objects that might house uranium or plutonium.