LCLS Overview Image

LCLS Overview

LCLS takes X-ray snapshots of atoms and molecules at work, providing atomic resolution detail on ultrafast timescales to reveal fundamental processes in materials, technology and living things. Its snapshots can be strung together into “molecular movies” that show chemical reactions as they happen.

With over 13,000 scientific user visits in its first 10 years of operation, researchers from around the world have conducted groundbreaking experiments in fields as diverse as chemical catalysis, human health, quantum materials science, and the physics of planetary formation. Data from LCLS experiments have generated over 1450 articles in peer-reviewed scientific publications, with a quarter of them appearing in prominent journals like Science and Nature.​

Since the start of operations in 2009:


3,000+   Unique users 
900+       Experiments
1450+    Publications


A Broad Reach

LCLS is enabling pioneering research across many fields:

How It Works

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LCLS was the first laser in the world, and one of just two now in operation, to produce "hard," or very-high-energy X-rays. The process of producing X-ray pulses starts in a section of SLAC's linear accelerator.

First a drive laser generates a precise pulse of ultraviolet light, which travels to an injector "gun" and strikes the surface of a copper plate. The plate responds by releasing a burst of electrons, which are accelerated by a series of devices to boost their energy.

The electron pulses then enter the LCLS Undulator Hall, the heart of LCLS, where they are put to work generating X-ray laser light.

Overview Image
Overview Image

The Undulator Hall houses thousands of special magnets, spaced a few millimeters apart and arrayed so their north-south magnetic poles alternate. The poles alternately attract and repel passing electron bunches, which swerve back and forth in an undulating motion that forces them to give off X-rays.

As each electron bunch travels with its associated X-rays, they start to interact with each other. The electrons arrange themselves in parallel sheets; this causes the waves of X-ray light to line up so their crests and troughs match, creating “coherent” or laser light and greatly boosting the power of the X-ray pulses. At this point the electrons are no longer needed; they are safely discarded, and the X-ray laser pulses continue in a straight line to LCLS experiments, arriving at a rate of up to 120 pulses per second.

X-rays are delivered to any of seven specialized experimental stations, and in some cases to multiple stations simultaneously. Each station has a dedicated team of scientists and support staff who spearhead R&D efforts, engage in innovative research and assist users with experiments.

Each station is equipped with a suite of instruments that use specialized techniques to gather data, from telltale signatures of electrons and ions to the intricate patterns left by crystallized samples struck by the X-ray laser.

What's Next

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A major upgrade to the facility, known as LCLS-II, is underway. This will provide a revolutionary leap in capability by increasing the X-ray pulse repetition rate from 120 pulses per second to 1 million pulses per second!

LCLS-II will be a transformative tool for energy science, qualitatively changing the way that X-ray imaging, scattering and spectroscopy can be used to study how natural and artificial systems function. It will enable new ways to capture rare chemical events, study quantum materials with unprecedented resolution, and track the behavior of fluctuation biological systems.

With LCLS-II, SLAC will continue to advance the frontiers of X-ray research, keeping the United States at the forefront of this very competitive international arena and supporting transformational science for the coming decade.

LCLS-II: The Next Leap for X-ray Science

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Further Exploration