High-Energy Physics at LLNL

LLNL’s High-Energy Physics (HEP) program supports fundamental research in advanced detector development, dark matter searches, the properties of neutrinos, and the search for the Higgs boson and supersymmetry. We are also conducting cutting-edge accelerator development and theoretical investigations of physics beyond the standard model.

The work we do for the Office of Science’s HEP program has synergy and overlaps with the Laboratory’s national security mission. The scientists engaged in HEP research apply their skills and expertise across the span of programmatic work at LLNL, which includes nonproliferation, stockpile stewardship, homeland security, National Ignition Facility, and high-performance computing facilities.

Researchers hold an optical filter
LLNL researchers designed the primary optics for the camera system at the Vera C. Rubin Observatory, including the world’s largest optical lens and six optical filters.

Cosmic Frontier

Axion Dark Matter Experiment (ADMX)

ADMX is the U.S. flagship search for dark matter axion particles. It uses a microwave cavity in a high field magnet solenoid to search for axions converting to detectable photons. The ADMX experiment is the only operating axion dark matter direct search sensitive to the quantum chromodynamics (QCD) axion in the most likely mass range (approximately a few to tens of microeV). The discovery of the axion would solve several longstanding mysteries in physics such as the nature of dark matter and the strong Charge+Parity (CP) problem (or the curious absence of a measurable electric-dipole in the neutron).

Capabilities Unique to LLNL: ADMX was originally constructed at LLNL in the 1990s before moving to the University of Washington in 2010. At LLNL we have unique facilities for microwave cavity construction on onsite copper plating and cryogenic testing systems. In addition, LLNL has millikelvin refrigerators to test and verify the quantum amplifier packages used.

Collaborators: University of Washington, University of Florida, Fermi National Laboratory, Pacific Northwest National Laboratory, University of California at Berkeley, Washington University in St. Louis, Sheffield University, and the National Radio Astronomy Observatory.

Liquid Underground Xenon (LUX) Dark Matter Experiment

LUX consisted of a large (370 kg) dual-phase liquid xenon that set some of the leading sensitivity limits for WIMP dark matter and has laid the groundwork for the next-generation LZ experiment. The LZ experiment represents the flagship direct search for WIMP dark matter particles in the standard mass range (ten GeV to TeV mass). LUX has made some of the world-leading sensitivity measurements in its search for WIMP dark matter and the data continues to be analyzed to inform future experiments based on dual-phase liquid xenon, such as the LZ experiment (the direct successor to LUX).

Capabilities Unique to LLNL: LLNL has developed ultralow-background test stands to explore the ultimate background resolution and energy threshold for liquid xenon-based detectors. This includes taking advantage of both the expertise at LLNL in rare event detection and in taking advantage of unique LLNL facilities such as the Center for Accelerator Mass Spectrometry (CAMS).

Collaborators: The Liquid Underground Xenon (LUX) experiment collaboration was composed of over 100 scientists and engineers across 27 institutions in the U.S. and Europe. The LZ experiment is an international collaboration that consists of 250 scientists and engineers from 37 institutions.

Vera Rubin Observatory Legacy Survey of Space and Time (LSST) Camera

The LSST is a unique telescope that will survey the entire night sky every few days, generating 500 petabytes of images and data to study the structure of the universe. LLNL's major hardware deliverable is the optics systems for the LSST camera system, one of the largest camera systems in the world. LLNL is also leading a team of scientists to develop advanced algorithms for reduction of systematic errors in weak gravitational lensing. The LSST will bring optical astronomy squarely into the age of Big Data. It will aim to answer questions on the structure of the universe and on the nature of dark energy and dark matter as well as exploring galaxy formation and solar system objects.

Capabilities Unique to LLNL: LLNL leveraged expertise developed in designing and fabricating large-scale optical systems for the National Ignition Facility for this basic science project, capabilities that are directly applicable to LLNL’s space security mission. We are also leveraging LLNL’s technical expertise in space situational awareness and systematic error reduction and quantification, including the development of advanced data pipelines for studying dark energy as well as searching for transient events such as microlensing or potentially hazardous asteroids.

Collaborators: The Vera Rubin Observatory LSST Project collaboration and the Dark Energy Science Collaboration.

Intensity Frontier


The Precision Oscillation and Spectrum Experiment (PROSPECT) is a short-baseline anti-neutrino detector that is searching for possible short-range neutrino oscillations that could indicate the presence of a new sterile neutrino. This above-ground segmented detector is also providing precision tests of our understanding of nuclear fission products. PROSPECT has released some of the most precise measurements of the anti-neutrino flux and energy spectrum from very short (7–9 meters) distance from the compact High Flux Isotope Reactor core at Oak Ridge National Laboratory.

Capabilities Unique to LLNL: LLNL has a long track record of designing and deploying ultrasensitive neutrino detectors with discrimination capabilities that allow them to make precise measurements above ground where there is a high background from cosmic rays.

Collaborators: Brookhaven National Laboratory, Drexel University, Georgia Institute of Technology, Illinois Institute of Technology, Le Moyne College, National Institute of Standards and Technology, Oak Ridge National Laboratory, Temple University, College of William and Mary, University of Wisconsin, and Yale University.

Advanced Detectors

Advanced Instrument Testbed (AIT) WATCHMAN Project

The AIT WATCHMAN project is a water-based antineutrino detector specifically designed to study the feasibility of using antineutrinos, which are impossible to shield but also extremely difficult to detect, as a method to search for clandestine nuclear reactors. LLNL is leading the effort to characterize the scattering. The Laboratory has developed unique capabilities from building and deploying antineutrino detectors near to nuclear reactors.

Liquid Noble Detector Research and Development

The Liquid Noble Detector Research and Development project is focused on discovering the causes of low-energy noise in ultrasensitive detectors such as those that use noble liquids and high voltage to detect neutrinos and ionizing radiation from nuclear material. Understanding the processes for low-energy noise will lead LLNL scientists to methods to mitigate such backgrounds and increase detector sensitivity. LLNL has a long history of developing detector technology for pushing the thresholds of sensitivity, which complements ongoing work for other high-energy physics projects and national security needs.

Accelerator Stewardship

Ultrafast Fiber Lasers

Laser-based particle accelerators could represent a paradigm shift and obtain energies much higher than currently attainable with present accelerator technology. LLNL is a world leader in high-power laser systems and is leading the development of the novel pulse-stacking method to amplify the laser power with the goal of creating a high-repetition-rate high-power laser system based on fiber-optics.

Capabilities Unique to LLNL: This work leverages the facilities and expertise developed at LLNL for the National Ignition Facility project.

Collaborators: Lawrence Berkeley National Laboratory and the University of Michigan.

Big Aperture Thulium Lasers

LLNL has developed a novel new laser architecture, dubbed Big Aperture Thulium (BAT), that can provide a leap in power and repetition rate for laser-based accelerators. This novel laser optical material holds the promise of orders-of-magnitude improvements in performance.

Capabilities Unique to LLNL: The BAT leverages LLNL's expertise with the most powerful laser system in the world—National Ignition Facility (NIF)—to push the envelope for new laser-based accelerators. This includes the engineering and materials capabilities to handle the extreme thermal loads for large optics (specifically the helium gas cooling system developed at LLNL for previous high-power lasers such as HAPLS and Mercury).

Collaborator: The Big Aperture Thulium Laser is a potential technology for the k-BELLA upgraded laser facility at Lawrence Berkeley National Laboratory.


Lattice for Beyond the Standard Model Physics

LLNL high energy theory uses supercomputers to calculate interactions and parameters for theories that require discrete, nonperturbative approaches, such as lattice quantum chromodynamics. LLNL scientists have led the developments of new “composite” dark matter candidates and specifically the idea of “stealth” dark matter in which quarks are bound by new strong interactions. These quarks would form composite particles hundreds of times heavier than a proton and their production in the early universe may be imprinted on gravity waves. They have also developed and computed key parameters of a composite Higgs model.

Capabilities Unique to LLNL: LLNL is using some of the world’s largest supercomputers in the world and applying massive computing power to efficiently run the complex calculations for lattice quantum chromodynamics (QCD) measurements.

Collaborator: Lattice Strong Dynamics Collaboration


Gianpaolo Carosi

Lab Program Coordinator for HEP at LLNL

carosi2 [at] llnl.gov (carosi2[at]llnl[dot]gov)