SLAC, a two-mile particle accelerator jutting west from Stanford University, pushes electrons near the speed of light. Back when it was still called the Stanford Linear Accelerator, SLAC was used for seminal particle physics discoveries decades ago.
It's now called the SLAC National Accelerator Laboratory, and its newer mission turns electrons into powerful X-ray lasers at a facility called LCLS (Linac Coherent Light Source). This tunnel links the two LCLS experimental chambers, with X-rays coasting along through the pipes after being generated upstream at a structure called the undulator.
Scientists prepare an experiment at the Soft X-ray Material Science instrument at SLAC's X-ray laser at the LCLS site, which has extended the useful life of the particle accelerator. These researchers are working on an experiment that uses X-ray scattering to study a copper oxide high-temperature superconductor.
SLAC's X-ray Pump Probe (XPP) experiment station uses optical laser light to excite materials that are then studied with X-ray laser pulses. The X-ray laser reveals behavior on ultrashort time scales. Most of the complex equipment in the center here is for the X-ray beam line; the unadorned pipe in the foreground carries another laser beam.
Purple tracks let researchers steer a camera at the X-ray Correlation Spectroscopy (XCS) experiment station through a wide range of angles and distances to measure light scattered off subjects blasted with X-ray lasers.
This section of SLAC shows the basic structure of a linear accelerator: modules built side by side, each giving electrons a bit more of a speed boost. SLAC uses two miles of copper cavities filled with radio waves to push electrons and their antiparticles, positrons, to high speed and high energy.
SLAC accelerates electrons and positrons with bursts of high-power microwave energy originating from dozens of devices called klystrons. Each one produces about 60,000 times the power of a kitchen microwave oven. Devices called waveguides, such as the one shown here, direct microwaves from the klystrons to the accelerating cavities.
SLAC's electron beam must travel through a vacuum, or else acceleration would be limited by short-circuit problems. SLAC operators test each junction carefully for leaks, and those that pass muster are marked with a foil wrapper, as on this vacuum piping. The vacuum has a pressure on the order of one hundred billionth of Earth's atmosphere.
One SLAC research area focuses on reconstructing the formation of the universe. We're familiar with galaxies, but this simulation shows strands of dark matter that lace the cosmos. Galaxies form at the brighter nodes where the density is highest.
In a project called FACET, SLAC is experimenting with the use of plasma to accelerate electrons. The plasma -- a high-energy gas made of atoms and their stripped-off electrons -- can be used to accelerate electrons 1,000 times more powerfully than conventional accelerators. This metal box itself is a powerful linear accelerator. SLAC just shut down FACET and is upgrading to FACET-II.
The original access ladders down to the linear accelerator chambers look like like they belong in a submarine. Nowadays, it's easier to get in, with stairways built in larger access routes that originally were used to lower hardware into the accelerator chamber.
This view shows SLAC's two-mile linear accelerator, looking east from the point where electrons begin their quick trip to near light speed. This end of the accelerator is being upgraded as part of a $1 billion project to boost SLAC's X-ray laser research abilities. In the distance are Stanford University's Hoover Tower and the southern tip of the San Francisco Bay.
This chamber, a vacuum that seals out air, holds samples probed by SLAC's Coherent X-ray Imaging (CXI) experiment station. It's mostly used to study protein crystals. Yes, somebody turned two of the observation ports into eyes for a face, with a grinning mouth below.
Aaron Roodman, an experimental cosmologist, explains SLAC's work on a multi-institution collaboration to build a massive telescope in Chile called the Large Synoptic Survey Telescope (LSST). The camera in the telescope is the size of a small car, and SLAC is building its image sensor. He stands in front of a clean room sealed to keep contaminants away from delicate electronics.
Here is an illustration of the wide swath of night sky the LSST will be able to photograph in a single image. It's big enough to photograph the entire sky every three or four nights, so astronomers and astrophysicists can track changes in the appearance and position of stars, galaxies and solar system objects. SLAC is assembling the camera's image sensor, made of 189 square, 16-megapixel sensors, each 42mm on edge.