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Archives, History & Records Office

Hours: By appointment Monday-Friday during regular work hours.


Archives E-mail: slacarc[@]
RM E-mail: recordsmgt[@]
Phone: (650)926-3091
Post: SLAC Archives and History Office, M/S 82, 2575 Sand Hill Road, Menlo Park, CA 94025.

Office Location: Bldg.50, Rm.122

SLC and SLD (1980-1998)

In 1979 the "electroweak theory," predicting the existence of "neutral intermediate vector bosons" -- also called the "W" and "Z" particles -- won the Nobel Prize in Physics. This led to an international race to be the first to detect the predicted bosons and, once discovered, the first to explore their properties.

 Glashow Particle Chart, 1976
The known elementary particles in 1976
(chart by Sheldon Glashow)

The seminal event leading to the realization of the first linear collider – a machine where two linear accelerators face off and collide beams – was a workshop at Fermilab in 1978. Skrinsky from Novosibirsk, Tigner from Cornell, Richter from SLAC, and a few others holed up for two undistracted weeks and worked out all the important ideas.

first page of 1978 conference paper on colliders
First page of paper written at the 1978 conference

Later, Richter proposed the SLAC Linear Collider (SLC), which would use SLAC's existing single linac to accelerate both electrons and positrons and use a tennis racket shaped system of magnets to bring them together.

The arcs of the SLC “tennis racket” would be in a tunnel below the ground surface, following the terrain. This made the paths of the electrons and positrons rather complicated – the SLC was the first and probably the last terrain-following machine!

The SLC started with electrons which were accelerated to make positrons, and then more electrons and the positrons were accelerated down the 3-kilometer linac and split into the two arcs.

On their way to colliding at the center of the detector, the beams were focused to less than 0.5 micron high and few microns wide. After each collision, the beams continued into beam dumps, a process repeated 120 times per second

color drawing of SLC and SLD
Artist's conception of SLC & SLD on SLAC site

SLC schematic, 1983

The energy generated by colliding SLC beams was large enough to create Z particles.

SLC began operations using the existing MARK-II detector. To make the most of the properties of particle collisions at the SLC, a collaboration from 18 institutions designed and built a detector optimized for Z research, the SLAC Large Detector (SLD), which began taking data in 1991.

SLD, cutaway view

SLD under construction in Collider Hall
SLD under construction in the Collider Hall, December 21, 1987

SLD under construction in Collider Hall
Staff working inside the SLD, February 6, 1990

Although CERN’s Super Proton Synchrotron (SPS) in Europe first discovered the W and the Z in 1983 -- SLC and the round Large Electron Positron (LEP) at CERN had profound scientific careers in Z physics.

Z production chart, 1992
May 2, 1992 chart of Z particle production history

SLC's tiny electron beam had a unique feature: its bunches were polarized to be either left­-spinning or right­-spinning. The resulting asymmetry in how the left and right electrons behaved when coupling to the Z gave SLD the single best measurement of the "weak mixing angle."

During their seven-year lifetimes, SLC produced and SLD detected and studied several hundred thousand Z's, and correctly deduced the mass of the Higgs, later to be discovered in a gargantuan effort at CERN’s Large Hadron Collider – the LHC.

polarized beam source schematic
Polarized beam source schematic

Left and right asymmetry at the SLD
Left and right asymmetry at the SLD

In addition to studying Z bosons, SLD used its extremely precise vertex detection system to identify and study the electroweak interactions of the heavy charm and bottom quarks produced by SLC collisions.

SLC vertex detector
SLC vertex detector on display in former SLAC Visitors' Center

vertex detector assembly; klystron clean room assembly, 06/19/1987

Three Generations of Leptons and Quarks, 1980
What was known about leptons and quarks in 1980
(Illustration from March 1980 SLAC Beamline article on " The State of SLAC" by W. K. H. Panofsky)

Harvey Lynch photo of SLD and collaboration members
SLD and collaboration members in the Collider Hall pit, December 7, 1990 (Harvey Lynch photo)

SLC Technical Publications

Index entries in inSPIRE for SLC-related papers, most include links to online full-text versions.

SLD Technical Publications

Index entries in inSPIRE for SLD-related papers, most include links to online full-text versions.

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Last Updated: 07/11/2022