The Superconducting Super Collider was designed to allow scientists to conduct a new class of experiments in particle physics to test theories of subatomic structure and the nature of matter.
In June, 1987, President Ronald Reagan approved the recommendations of prominent physicists, leaders in the U.S. Congress, and other federal officials that the United States should construct a gigantic particle accelerator called the Superconducting Super Collider (SSC). After protracted discussion and lobbying by many states, in November, 1988, President Reagan approved a construction site near Waxahachie, Texas, in Ellis County, about 50 kilometers (roughly 31 miles) south of Dallas. The SSC—a near-circular tunnel 87 kilometers (about 54 miles) in circumference housing thousands of superconducting magnets—was designed to generate collisions of proton beams at energies up to 40 trillion electronvolts (40 TeV), energy levels twenty times greater than can be produced by the most powerful particle accelerator in operation in 1990.
Accelerators are the engines that drive research in elementary particle physics—the study of the basic nature of matter, energy, space, and time. They have produced fundamental changes in how scientists view these phenomena as well as the very nature of the universe. Until about 1960, matter was understood to consist simply of protons, neutrons, and electrons, the building blocks of atoms. As physicists attempted to learn about the forces binding these particles into atoms and nuclei, by driving them to high-energy collisions in small accelerators, or cyclotron rings, they discovered more than one hundred previously unknown particles. Most of these particles had properties similar to those of neutrons and protons, and are collectively classified as hadrons. Hadrons, in turn, appear to be composed of even more elementary particles called quarks. Although electrons appear to be elementary particles themselves, there are about six electron-like particles known as leptons.
Miners move through the tunnel of the Superconducting Super Collider near Waxahachie, Texas, in 1993, the year Congress aborted the costly project.
Physicists also have identified four forces involved in organizing matter. Three of these forces—electromagnetism, the weak force (involved in certain types of radioactive decay), and gravitation—act on both hadrons and leptons. The fourth force, however, known as the strong force, appears to bind quarks together to form hadrons
In the late twentieth century, physicists actively pursued attempts to devise a grand unified theory
Most early accelerators were linear machines in which magnets drove particle beams in a straight line to collisions with fixed targets. Although linear accelerators can achieve energy levels in the billions of electronvolts, much energy is lost in colliding with a fixed target. Ring colliders, which are essentially circular accelerators, can achieve much higher energy levels and thus reveal the presence of higher-energy particles. Rather than focusing a beam on a fixed target, a ring collider focuses two beams in opposite directions from a source point. The beams then collide with each other at very high energy levels, just as a head-on collision of two automobiles is more “energetic”—and therefore more destructive—than the impact of an automobile against a tree.
Particles are driven to high energy levels in ring colliders by magnets. The larger the circumference of the ring and the more powerful the magnets, the higher the energy levels that are produced in the particle beams. The largest existing rings—at the Fermi National Accelerator Laboratory near Chicago (Fermilab)
The SSC not only would be the largest ring collider facility in the world by a large margin but also would employ about eight thousand sophisticated magnets using superconductivity technology. Superconductivity is a phenomenon in which certain materials, when bathed in liquid helium or otherwise lowered in temperature to a point close to absolute zero, conduct electromagnetic force with almost 100 percent efficiency. Each superconducting magnet in the SSC, as originally designed, was to be about 17 meters (about 56 feet) in length. The particle beams were to be driven through one magnet after another until their energy levels became so great that particle velocities approached the speed of light. These magnets were the most costly component of the SSC project, the total initial estimated cost of which was $4.5 billion, making it second only to the Apollo manned lunar project as the costliest scientific enterprise funded by the federal government. The magnets also proved extremely troublesome and forced numerous delays in the project schedule. Although the advanced cryogenics for supercooling worked well, and shorter versions of the magnet assembly worked perfectly, scaling up the technology to the 17-meter length required in the SSC created difficulties. In effect, the longer magnets introduced a “bend” in the beam, resulting in lower energy levels.
The repeatedly poor performance of prototype magnets led the U.S. Department of Energy
Just as it had been during the furious lobbying by several states to decide on a site, the SSC became a major political issue again because of the magnet problems. The alternatives were to accept a somewhat less powerful SSC, leave the magnet design in place, and proceed with construction, or to redesign the magnets and possibly the ring itself. Physicists throughout the world argued against acceptance of a power loss as unacceptable in the light of the enormous expense involved in building and operating the SSC. At 40 TeV, the ring provided a margin of power of critical importance for certain experiments; even a 10 percent decrease would mean the loss of that margin.
The SSC central design group recommended the second alternative: design changes to overcome the problem of power loss in the magnets, including shortened magnets of about 16 meters (about 52 feet), a larger number of magnets, possible extension of the ring circumference by about 3 kilometers (almost 2 miles), and upgrading of the linear booster accelerator to inject protons into the ring at about 1 TeV. The problem with such basic design changes was cost. Some analysts estimated that they would result in a cost overrun of more than $2 billion, raising the overall cost of the SSC by almost 50 percent.
Recommendations for design changes came on the heels of some second thoughts in an austerity-minded Congress. Despite an increased appropriation of $200 million in fiscal 1990, scrutiny of the SSC project by the administration of President George H. W. Bush
In 1993, Congress finally aborted funding of the SSC, effectively calling a halt to the project. The economic and financial aspects of the SSC had, perhaps inevitably, occupied everyone in the siting, design, and planning stages. The SSC was to have a community of three thousand scientists and engineers and an annual operating budget of nearly $300 million. The staff would have required housing and conveniences; the collider itself would have consumed enormous amounts of power.
Given that one of the criteria in site choice was the proximity of a network of universities and laboratories, the SSC was expected to have a synergistic effect on the development of high-technology industry and research.
The SSC would also have ensured U.S. primacy over Europe in the race to find the final answers in elementary particle research. One of the most dramatic science projects in history, the SSC had the potential to rival in importance the space program that placed the first human on the Moon. However, the rising budget deficit and the political concerns surrounding an economic recession dealt a death blow to the project.
The SSC represented a huge step beyond the current frontiers of high-energy physics. Despite the project’s failure, physicists remain hopeful that someday the elusive Higgs boson,
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Fisher, Arthur. “The World’s Biggest Machine: Superconducting Super Collider.” Popular Science 230 (June, 1987): 56-62. Provides informative discussion of the principles of particle physics experiments envisioned for the SSC and describes the project for general readers. -
Halzen, Francis, and Alan D. Martin. Quarks and Leptons: An Introductory Course in Modern Particle Physics. New York: John Wiley & Sons, 1984. Textbook addresses the main developments and research foci of particle physics. Assumes that readers have extensive mathematical background (as do all textbooks in this field). Includes bibliography. -
Levi, Barbara Goss, and Bertram Schwarzschild. “Super Collider Magnet Program Pushes Toward Prototype.” Physics Today 41 (April, 1988): 17-21. Clearly written, illustrated summary of the technology and manufacturing procedures committed to the controversial first generation of SSC magnets. Includes discussion of the causes of disappointing test results. -
National Research Council. Physics Survey Committee. Physics Through the 1990’s. Washington, D.C.: National Academy Press, 1986. Presents the proceedings and recommendations of the NRC panel that outlined priorities for research in elementary particle physics in the United States through the early twenty-first century. The panel recommended construction of the SSC as the highest national priority, central to the future of American research and leadership in the field. -
Ne’eman, Yuval, and Yoram Kirsh. The Particle Hunters. 2d ed. New York: Cambridge University Press, 1996. Provides a historical account of the process of particle discoveries at ever-increasing energy levels, leading to the need for more powerful accelerators. Includes particularly good discussion of particle properties and basic forces in language suitable for general readers. -
Okun, L. B. Particle Physics: The Quest for the Substance of Substance. Translated by V. I. Kisin. New York: Harwood Academic, 1985. Discusses theoretical issues in particle physics. Rather technical in places but informative and readable for individuals with some mathematical and scientific background. Includes an extensive glossary and one of the most extensive bibliographies on particle physics available outside of specialized publications. -
Perkins, Donald H. Introduction to High Energy Physics. 4th ed. New York: Cambridge University Press, 2000. Textbook presents detailed mechanical and operational descriptions of accelerators and other experimental equipment. For readers with mathematics and physics background. Includes glossary, bibliography, and index.
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