FACET-II

FACET-II is a premier national user facility for advanced accelerator science located at the SLAC National Accelerator Laboratory in Menlo Park, California. It is a major upgrade to the original FACET facility, designed to provide the world's highest-energy and highest-quality beams of Electrons and Positrons for pioneering experiments. The facility enables research into novel particle acceleration techniques and advanced radiation sources, supporting the long-term goals of projects like the International Linear Collider and advancing fundamental plasma physics.

Overview

FACET-II represents a significant evolution in the United States Department of Energy's portfolio of accelerator test facilities, building upon the legacy of its predecessor and the historic Stanford Linear Collider. Its primary mission is to explore revolutionary methods for accelerating particles using Plasma wakefield acceleration and Dielectric laser acceleration, which promise to make future colliders like the Compact Linear Collider more powerful and affordable. The facility operates as an open-access resource for the global scientific community, hosting researchers from institutions like the University of California, Los Angeles, the University of Oxford, and the Deutsches Elektronen-Synchrotron. This collaborative environment is managed under the auspices of the DOE Office of Science.

Technical specifications

The heart of the facility is a dedicated segment of the original two-mile-long SLAC linac, capable of delivering electron beams up to 10 GeV and high-density positron beams. A key feature is its ability to produce ultra-short, high-current electron bunches with unprecedented brightness, which are essential for driving intense plasma waves. The beamline incorporates advanced systems for diagnostics and manipulation, including sophisticated Laser systems for precision timing and injection. Critical infrastructure, such as the state-of-the-art Control room and Cryogenic plants, supports continuous operation. The design also integrates flexible experimental areas like the End Station A to accommodate a wide array of specialized instrumentation.

Research capabilities

The core experimental program focuses on Plasma wakefield acceleration, where a driver beam creates a wake in a plasma that can accelerate a trailing witness beam to high energies over very short distances. Complementary research explores Dielectric laser acceleration using micro-fabricated structures powered by intense Laser pulses. The facility also pioneers the generation of novel radiation sources, such as intense X-ray pulses via Free-electron laser mechanisms and Terahertz radiation for material studies. These capabilities enable investigations into high-field Quantum electrodynamics and support the development of advanced concepts for future light sources like the Linac Coherent Light Source II.

Experimental achievements

Since its commissioning, the facility has demonstrated groundbreaking results, including the stable acceleration of electrons in a plasma wakefield with high energy transfer efficiency. Notable experiments have shown successful positron acceleration in plasma, a significant challenge for the field. Researchers have also achieved record-breaking gradients in dielectric structures and produced bright, tunable beams of Terahertz radiation for probing materials. These milestones provide critical validation for theoretical models developed at institutions like the Lawrence Berkeley National Laboratory and inform the design of proposed future machines, contributing to the broader goals of the Particle physics community.

Collaboration and operation

FACET-II operates as a fully international user facility under the management of SLAC National Accelerator Laboratory, with guidance from the DOE Office of Science and support from the National Science Foundation. Its user program is overseen by a scientific advisory committee with members from global partners like CERN, the University of Tokyo, and the Rutherford Appleton Laboratory. Proposals are selected through a peer-review process, and teams from universities, national laboratories, and international consortia conduct experiments. The facility plays a central role in training the next generation of accelerator scientists and maintains strong ties with adjacent projects at SLAC, including the Linac Coherent Light Source. Category:Particle accelerators Category:Research facilities in California Category:SLAC National Accelerator Laboratory