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Stanford Linear Accelerator Center

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Stanford Linear Accelerator Center

"SLAC" redirects here. For other uses, see SLAC (disambiguation).

SLAC National Accelerator Laboratory
Established 1962
Research type Physical Sciences
Field of research Accelerator physics
Photon science
Director Chi-Chang Kao
Staff 1,700
Address 2575 Sand Hill Rd.
Menlo Park, CA 94025
Location Menlo Park,California, USA
Campus 426 acres
Nickname SLAC
Affiliations US Department of Energy
Stanford University
Nobel laureates Burton Richter
Richard E. Taylor
Martin L. Perl

SLAC National Accelerator Laboratory, originally named Stanford Linear Accelerator Center,[1][2] is a United States Department of Energy National Laboratory operated by Stanford University under the programmatic direction of the U.S. Department of Energy Office of Science.

The SLAC research program centers on experimental and theoretical research in elementary particle physics using electron beams and a broad program of research in atomic and solid-state physics, chemistry, biology, and medicine using synchrotron radiation.


Founded in 1962 as the Stanford Linear Accelerator Center, the facility is located on 426 acres (1.72 square kilometers) of Stanford University-owned land on Sand Hill Road in Menlo Park, California—just west of the University's main campus. The main accelerator is 2 miles long—the longest linear accelerator in the world—and has been operational since 1966.

Research at SLAC has produced three Nobel Prizes in Physics:

SLAC's meeting facilities also provided a venue for the Homebrew Computer Club and other pioneers of the home computer revolution of the late 1970s and early 1980s.

In 1984 the laboratory was named an ASME National Historic Engineering Landmark and an IEEE Milestone.[6]

SLAC developed and, in December 1991, began hosting the first World Wide Web server outside of Europe.[7]

In the early-to-mid 1990s, the Stanford Linear Collider (SLC) investigated the properties of the Z boson using the Stanford Large Detector.

As of 2005, SLAC employs over 1,000 people, some 150 of which are physicists with doctorate degrees, and serves over 3,000 visiting researchers yearly, operating particle accelerators for high-energy physics and the Stanford Synchrotron Radiation Laboratory (SSRL) for synchrotron light radiation research, which was "indispensable" in the research leading to the 2006 Nobel Prize in Chemistry.[8]

In October 2008, the Department of Energy announced that the Center's name would be changed to SLAC National Accelerator Laboratory. The reasons given include a better representation of the new direction of the lab and the ability to trademark the laboratory's name. Stanford University had legally opposed the Department of Energy's attempt to trademark "Stanford Linear Accelerator Center".[1][9]



The main accelerator is an RF linear accelerator that can accelerate electrons and positrons up to 50 GeV. At 2.0 miles (about 3.2 kilometers) long, the accelerator is the longest linear accelerator in the world, and is claimed to be "the world's straightest object."[10] The main accelerator is buried 30 feet (about 10 meters) below ground[11] and passes underneath Interstate Highway 280. The above-ground klystron gallery atop the beamline is the longest building in the United States.

Stanford Linear Collider

The Stanford Linear Collider was a linear accelerator that collided electrons and positrons at SLAC.[12] The center of mass energy was about 90 GeV, equal to the mass of the Z boson, which the accelerator was designed to study. Grad student Barrett D. Milliken discovered the first Z event on 12 April 1989 while poring over the previous day's computer data from the Mark II detector.[13] The bulk of the data was collected by the SLAC Large Detector, which came online in 1991. Although largely overshadowed by the Large Electron-Positron Collider at CERN, which began running in 1989, the highly polarized electron beam at SLC (close to 80%[14]) made certain unique measurements possible.

Presently no beam enters the south and north arcs in the machine, which leads to the Final Focus, therefore this section is mothballed to run beam into the PEP2 section from the beam switchyard.

SLAC Large Detector

The SLAC Large Detector (SLD) was the main detector for the Stanford Linear Collider. It was designed primarily to detect Z bosons produced by the accelerator's electron-positron collisions. The SLD operated from 1992 to 1998.


From 1999 to 2008, the main purpose of the linear accelerator was to inject electrons and positrons into the PEP-II accelerator, an electron-positron collider with a pair of storage rings 1.4 miles (2.2 km) in circumference. PEP-II was host to the BaBar experiment, one of the so-called B-Factory experiments studying charge-parity symmetry.

Stanford Synchrotron Radiation Lightsource

The Stanford Synchrotron Radiation Lightsource (SSRL) is a synchrotron light user facility located on the SLAC campus. Originally built for particle physics, it was used in experiments where the J/ψ meson was discovered. It is now used exclusively for materials science and biology experiments which take advantage of the high-intensity synchrotron radiation emitted by the stored electron beam to study the structure of molecules. In the early 1990s, an independent electron injector was built for this storage ring, allowing it to operate independently of the main linear accelerator.

Fermi Gamma-ray Space Telescope

SLAC plays a primary role in the mission and operation of the Fermi Gamma-ray Space Telescope, launched in August 2008. The principle scientific objectives of this mission are:

  • To understand the mechanisms of particle acceleration in AGNs, pulsars, and SNRs.
  • To resolve the gamma-ray sky: unidentified sources and diffuse emission.
  • To determine the high-energy behavior of gamma-ray bursts and transients.
  • To probe dark matter and fundamental physics.


The Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) is partially housed on the grounds of SLAC, in addition to its presence on the main Stanford campus.


The Linac Coherent Light Source (LCLS) is a free electron laser facility located at SLAC. The LCLS is partially a reconstruction of the last 1/3 of the original linear accelerator at SLAC, and can deliver extremely intense x-ray radiation for research in a number of areas. It achieved first lasing in April 2009.[15]

The laser uses hard X-rays, 109 times the relative brightness of traditional synchotron sources and is the most powerful x-ray source in the world. LCLS enables a variety of new experiments and provides enhancements for existing experimental methods. Often, x-rays are used to take "snapshots" of objects on the nearly atomic level before obliterating samples. The laser's wavelength is similar in width to an atom, providing extremely detailed images for objects previously unattainable.[16] Additionally, the laser is capable of capturing images with a "shutter speed" measured in femtoseconds, or million-billionths of a second, necessary because the intensity of the beam is such that it nearly instantly destroys its subject.[17]


The Stanford PULSE Institute (PULSE) is a Stanford Independent Laboratory located in the Central Laboratory at SLAC. PULSE was created by Stanford in 2005 to help Stanford faculty and SLAC scientists develop ultrafast x-ray research at LCLS. PULSE research publications can be viewed here.

Other discoveries

  • SLAC has also been instrumental in the development of the klystron, a high-power microwave amplification tube.
  • There is active research on plasma acceleration with recent successes such as the doubling of the energy of 42 GeV electrons in a meter-scale accelerator.
  • There was a Paleoparadoxia found at the SLAC site, and its skeleton can be seen at a small museum there in the Breezeway.[18]
  • The SSRL facility was used to reveal hidden text in the Archimedes Palimpsest. X-rays from the synchrotron radiation lightsource caused the iron in the original ink to glow, allowing the researchers to photograph the original document that a Christian monk had scrubbed off.[19]

See also


External links

  • SLAC official webpage
    • SLAC Today, SLAC's online newspaper, published weekdays
    • Fermilab

Coordinates: 37°24′53″N 122°13′18″W / 37.41472°N 122.22167°W / 37.41472; -122.22167

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