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6.2 MAGNET FABRICATION

During Phase I, development work on the dipole magnets for the collider rings has been emphasized. Dipole magnet models have been assembled at the Laboratories using industrial methods and industrially supplied components. Essential parts of the associated technology have been transferred to industry. These steps will enable the laboratories and industry to plan for a very early and rapid tooling up and start of magnet production early in the construction project. The accomplishments of the Phase I R&D work will also provide assurance that the SSC organization will be able to release the major contracts for material purchases and magnet assembly contracts that are indicated on the schedule shown on Fig. 6-3. The overall magnet production plan summary described in Fig. 6-3 shows the main dipole magnet fabrication plans along with the quadrupole magnet, spool piece, and other special magnet fabrication and installation plans.

The fabrication and installation of the main collider ring magnets has received considerable attention during the planning studies. The magnet production plan assumes that two (or more) industrial firms will manufacture the nearly 8000 dipole magnets required and ship them to the SSC for final testing and installation. The peak production rate of approximately 600 dipole units per quarter requires an efficient and aggressive work plan. Preliminary manufacturing studies by two industrial firms are already being reviewed, and the phased steps leading to authorized manufacturing contracts by several qualified vendors in early FY1988 are now being planned. Figure 6-3 shows the major dipole fabrication extending from mid-FY1989 (after production tooling is fabricated and installed from April 1988 through March 1989) through approximately May 1993, a period of approximately four years. The fabrication of the quadrupoles and spool pieces starts approximately one year later, in April 1989, and the installation of the half-cell units (each comprised of five dipoles, one quadrupole, and one spool) also commences in mid 1989.

6.3 INJECTOR SYSTEMS

Although the initial emphasis in the construction plan centers on the Collider Ring (the overall critical path track), a comprehensive start on the "Injector Systems" is also planned. While the overall start of the injector construction will necessarily await finalization of the detail siting studies and optimizations for the collider ring specification, an early start on the first injector system is planned such that an efficient stepwise "installationtest-acceptance" sequence follows for each of the Linac, Low Energy Booster, Medium Energy Booster, and High Energy Booster accelerators respectively, as indicated in Fig. 6-1.

6.4 COMMENTS

The information presented here is a preliminary summary-level schedule of major SSC systems. More complete and lower level details are being developed in the current activities leading to the SSC Conceptual Design Report (April 1986). Final schedule details for both technical and conventional systems will be provided in that document.

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In concert with the detailed construction schedules, the Conceptual Design Report will provide a comprehensive construction plan including all cost estimates, cost and manpower profiles, milestone charts, and critical path añalyses. The manpower projections will identify staffing requirements for management, design, and fabrication efforts during construction.

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Chapter 7

SUMMARY AND CONCLUSIONS

The Superconducting Super Collider or SSC is a proposed high-luminosity proton-proton accelerator and storage ring complex with beams of 20 TeV energy. The magnetic confinement system makes use of the phenomenon of superconductivity to produce high magnetic fields (and so smaller size) and to reduce greatly the electric power needed to operate the facility. Physically the SSC consists mainly of an underground tunnel 83 km (52 miles) in circumference around which protons circulate in opposite directions within two evacuated beam pipes inside separate rings of magnets. At six points the beams are made to intersect almost head-on. The interpenetrating bunches of protons produce only a few very high energy collisions at each crossing and so can repeatedly collide without degradation. Nevertheless, because oppositely moving bunches pass through each other every hundred millionth of a second, the experimenters studying the reactions have a very large data rate in their detectors. From the myriad of electronic signals recorded from a collision, the experimenters are able to identify the emerging particles and explore the inner dynamics of matter at distances a ten billion billion times smaller than human size.

The experimental discoveries and theoretical developements of the past 20 years have led physicists to a comprehensive description of matter as composed at the elementary level of quarks and leptons interacting via the exchange of force (gauge) particles. In the energy or mass region up to 0.1 TeV (100 GeV), this so-called standard model provides a remarkably successful framework consistent with all known observations. For all its noteworthy triumphs, the standard model still leaves many questions unanswered. It contains a large number (approximately 20) empirical parameters a reflection of its failure to explain the origin and pattern of particle masses, the observed groupings of quarks and leptons, the reason for the handedness of weak interactions, to name a few.

To address these and other unanswered questions, more powerful instruments are needed. A decade ago plans were laid to move beyond present capabilities. The Tevatron collider at Fermilab, the SLC at Stanford University, and LEP at the European Laboratory for Particle Physics (CERN) will soon begin to explore the edges of the new energy domain. But there are compelling reasons why, even as these facilities commence operation, a new instrument is required. The electron-positron colliders (SIC, LEP) will study the Z mass region of 0.1 TeV in detail. The Tevatron, with its colliding 1 TeV protons and anti

protons, will reach 0.3 TeV.

The standard model has so many correct aspects that one can tell with considerable certainty at what mass scale its obscurities will surely be illuminated. That mass is 1 TeV or greater. Only a high-luminosity multi-TeV hadron collider such as the SSC has the capacity to explore this mass range. The spectrum of predicted new particles and forces can be used to delimit the required parameters. Beam energies of 20 TeV and a luminosity of 1033 cm 25-1 are pinpointed as appropriate for the SSC.

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Despite its unprecedented size, the SSC is a natural and modest extension of existing accelerator technology and practice. Its technical basis lies in the cascaded synchrotrons of the world's major high energy physics laboratories, of which Fermilab in the U.S., CERN in Europe, and Serpukhov in the U.S.S.R. are examples. Fermilab is particularly relevant because of its pioneering use of superconducting accelerator magnets in the Tevatron.

Four years ago it was appreciated that the SSC was technologically feasible, with the Tevatron pointing the way. Two years ago, after a number of workshops and studies and a recommendation from the High Energy Physics Advisory Panel, the U.S. Department of Energy (DOE) initiated research and development activities to sharpen the design criteria and cost estimate of the SSC, as well as address identified technical problems. The R&D effort put major emphasis on superconducting magnets, the costliest single technical component of the system. An extensive model magnet program at Brookhaven National Laboratory, Fermilab, Lawrence Berkeley Laboratory and the Texas Accelerator Center has been remarkably successful. Enough high quality models have been made to establish one magnet style as superior and to assure that reproducible magnets of excellent field quality, field strength, and reliability can be built with methods that are applicable to large-scale industrial production.

Other aspects of the R&D program concerning the cost have been the development of improved superconducting wire in cooperation with industry, a study of beam dynamics to establish the smallest prudent transverse size of the magnets, and experiments on cold evacuated beam pipes in the presence of synchrotron radiation to assess the pumping needs for the SSC vacuum.

The two-year R&D effort has shown that the components of the SSC are thoroughly understood and that a reliable cost estimate and sensible construction plan for the complete facility can be developed. The Conceptual Design Report, of which this is a preview, will provide that information.

The general features of the SSC, both physically and technically, are described in Chapters 4 and 5. Briefly, the facility is mostly underground. Its 83 km tunnel is to be accessed only occasionally along its length. The oval shape of the ring is 28 km (17 miles) by 23 km (14 miles). On opposite sides are two clusters of interaction regions and other facilities. Apart from these areas and in a 200 meter wide path above the tunnel, the land encompassed by the SSC is undisturbed and available for normal use. The clusters have complexes of experimental support buildings, the cascade of smaller accelerators of the injector, and the central laboratory and office

area.

The largest number of the technical components are distributed in the tunnel. There are two complete beam pipes and magnetic confinement systems, consisting of regular arrays of bending and focusing magnets, nearly 10,000 in all, interrupted eight times around the tunnel by special sets of magnets for the interaction regions or the injection and abort sections. There are ten main refrigeration stations around the ring to provide the liquid helium and nitrogen to cool the magnets to their superconducting state. Elaborate distributed controls systems are provided to maintain the beams in proper paths through the evacuated beam pipes for a day or more before refilling.