DOWN to the WIRE TOM NAKASHIMA Building Fermilab'stevatron Accelerator BETTE REED Brought Science and Industry Together in a Unique Partnership

. CONTENTS ~~sr~GrsAMO

SPRING 1993 VOL. 23, NUMBER 1 FEATURES Editors RENE DONALDSON, MICHAEL RIORDAN 2 FROM THE EDITORS' DESK

Executive Editor 3 WHO NEEDS SCIENCE? BILL KIRK Curiosity about the natural world, pursued for its own sake, has always Guest Editor been a wellspring of innovation. DAVID HITLIN Frederick Reines

Editorial Advisory Board 6 LITTLE LINACS FIGHT CANCER Linear electron accelerators are used HITLIN JAMES BJORKEN, ROBERT N. CAHN, DAVID in medicine to treat millions of cancer STEWART C. LOKEN, RONALD RUTH patients every year. MARVIN WEINSTEIN, HERMAN WINICK John Ford Photographic Services 14 DOWN TO THE WIRE TOM NAKASHIMA Building Fermilab'sTevatron accelerator BETTE REED brought science and industry together in a unique partnership. Illustrations Judy Jackson TERRY ANDERSON, KEVIN JOHNSTON SYLVIA MACBRIDE, JIM WAHL 22 TECHNOLOGY TRANSFER AT SSRL From its inception, the Stanford Distribution Synchrotron Radiation Laboratory CRYSTAL TILGHMAN has worked closely with industry. Arthur Bienenstock

The Beam Line is published quarterly by the Stanford Linear Accelerator Center, 29 MICROWAVE TUBES P.O. Box 4349, Stanford, CA 94309. FOR SCIENCE & INDUSTRY Telephone: (415) 926-2585 INTERNET: [email protected] High power microwave sources developed BITNET: BEAMLINE@SLACVM for particle accelerators have potential FAX: (415) 926-4500 in emerging technologies. SLAC is operated by Stanford University under contract applications with the U.S. Department of Energy. The opinions of the George Caryotakis authors do not necessarily reflect the policy of the Stanford Linear Accelerator Center. 35 WHERE ARE THEY NOW? Cover: An EGS4 computer simulation of a cancer-therapy Six former high energy physicists who are accelerator operating in the electron mode. An initial group of 100 electrons (blue lines), each of 20 MeV, strike a scattering making their mark in the world. foil (dark blue and green), then pass through an ion chamber. Some x rays (yellow lines) are produced, and the beam is David Hitlin and Michael Riordan shaped by a succession of collimators. This simulation was created by Alex Bielajew and George Ding of the National 42 CONTRIBUTORS Research Council of Canada.

Printedon Recycled Paper4 44 DATES TO REMEMBER HE FIRSI I ticket and early ones in the sat.... There was National A cable an ti modationls the world' five millior In the proc| tivity like I materials sI that fast-fol industry to market cre< ventional I proton 4a: Ring ...... b.. e...E r, Because electric current that flows conducting magnets, the technology through superconducting wire of manufacturing superconducting doesn't lose energy to resistance, wire and cable was still "exotic," as magnets made with such wire use Leon Lederman, who became less electric power to achieve the Director of Fermilab in 1978 after high magnetic fields required by par- Wilson resigned, has written. ticle accelerators. It does take energy "Somewhere between magic and to cool the magnets, however, so the witchcraft," is where University of net reduction in power use is less Wisconsin metallurgist David than 100 percent. Larbalestier places it. Shortly after Heike Kamerlingh Using his own brand of magic, Onnes discovered superconductiv- Wilson brought together his avail- ity in 1911, he also discovered the able sources of expertise in super- bane of superconducting materials: conducting technology for the task quenching. This phenomenon occurs of designing and making the wire Above: Charles Laverick, left, Argonne when a superconducting material and cable. Fermilab physicists Wil- National Laboratory, and William Fowler reaches a certain critical current, liam Fowler, Paul Reardon and Russ of Fermilab during a 1974 conference temperature or magnetic field; it sud- Huson and metallurgist Bruce Strauss on applications of superconductivity. denly "goes normal," that is, returns had gotten their feet wet in super- to its nonsuperconducting state, re- conducting technology by building leasing its stored energy-and some- magnets for the 15-foot bubble cham- times melts. His discovery of this ber. John Purcell, a physicist from phenomenon also quenched Kamer- Argonne National Laboratory lingh Onnes's enthusiasm for the brought to the project his experience practical uses of superconductivity. in building its 12-foot bubble cham- It was not until the late 1960s that ber. superconducting technology reached The Applied Superconductivity the stage where it began to interest Laboratory at the University of the builders of particle accelerators. Wisconsin gave Fermilab another entree into the field of superconductivity. Attracted partly by the BETWEEN MAGIC wire-fabricating facilities designed AND WITCHCRAFT by specialist Remsbottom, Larbales- tier had come to Wisconsin from Many have credited Wilson with a Britain's Rutherford Laboratory, genius for bringing the right people- where he had worked on supercon- with the right skills and knowledge- ducting materials in the effort to together at the right time in order to understand how they work at a accomplish scientific goals that were, microscopic and molecular level. to say the least, challenging. He never "Larbalestier was our mentor in used this talent to better effect than superconductivity," says retired in the design and building of the Fermilab Associate Director J. Doubler. Ritchie Orr. "He made it his business In the mid- 19 70s, when physicists to understand how it really worked. " and engineers at Fermilab began try- Sixty years after Kamerlingh ing to design and build super- Onnes's disheartening discovery,

16 SPRING 1993 Engineer Willard Hanson and metallurgist Bruce Strauss test an early superconducting magnet.

quenching still caused problems for magnet builders at Fermilab, explains physicist Alvin Tollestrup, who, along with Orr and Fermilab physicists Richard Lundy and Helen Edwards, received the 1989 National Medal of Technology for their con- tributions to the Tevatron. A superconducting magnet uses coils of cable made of strands of superconducting wire to induce a magnetic field. The performance of a magnet made of such wire-its ability to reach and maintain a prescribed magnetic field without quenching-depends on right configuration, with the right approach had made enough progress many factors but fundamentally on materials on the surface of the strands to fix important wire and cable speci- the critical current of the supercon- and on the cable itself to achieve the fications. The cable would be a 23- ductor, that is, on the amount of highest critical current and appro- strand, flat, twisted "Rutherford current the wire can conduct, at its priate mechanical properties so that cable." The superconductor itself operating temperature and field, it can be wound into magnet coils. would be an alloy of 53.5 percent without quenching. Thus, says What kind of cable works best in niobium and 46.5 percent titanium, Tollestrup, the object of making su- superconducting magnets? Particle proportions chosen to be non- perconducting wire is to achieve accelerators have lived and died by proprietary and in the middle of the workable wire-that bends easily, the answer to that question. For range of proprietary alloys of the for example, and has precise dimen- years, magnet builders at Brookhaven various wire vendors. (Later research sions-with a high critical current. National Laboratory struggled to would show that the exact ratio of build superconducting magnets for niobium to titanium was not critical the ISABELLE collider using not flat in wire performance.) The work of IT'S NOT SO EASY cable but a braid of superconducting Fermilab physicists Fowler, Reardon wire. Many point to this choice of and Donald Edwards, metallurgist The would-be wire maker must com- braided cable as a fatal flaw that led Strauss, technical consultant Rems- bine the right alloy of the right su- to ISABELLE's demise when the De- bottom, and others ultimately pro- perconducting materials in the right partment of Energy withdrew fund- duced not simply a set of speci- configuration with a conventional ing for the project in 1983. fications for superconducting wire conductor, such as copper; then find These were problems that but a sort of "build-by-numbers" the right methods of heating and members of Wilson's Doubler group wire-making assembly, the so-called drawing the materials into wire, in took on in the early 1970s. "When it Fermilab Kit. order to achieve the requisite critical comes to making superconducting current and mechanical properties magnets," says metallurgist Strauss, that will allow the wire to be formed "a let's-try-it" approach works better BY THE TON? into cables. Finally, those materials than a theoretical one based on and methods must be adapted for calculations alone. If you think about As the needs of the magnet- mass-production of wire of uniform superconductivity too long, you'll development program increased, quality. The problem to solve in ca- realize it won't work. " By early 1975, Fermilab researchers began looking bling the wire is to find the right Fermilab's highly systematic and for manufacturers who could work number of strands of wire, in the tightly organized "let's-try-it" with them to supply large quantities

BEAM LINE 17 produced since the beginning of time. Niobium is mined in only a few places on earth-Brazil, Canada and China. In the 1970s China was not a practical source, and the ores with the highest concentration came from Brazil. Most of Fermilab's niobium alloy came from Brazilian ores until climbing export taxes sent Wah Chang to Canadian sources. In the spring of 1974, Reardon, Above left: Each wire strand contained of superconducting wire and cable Strauss and contracts manager Ed- 2100 filaments of superconductor. The that would meet the specifications ward West made a trip, legendary in New England Electric Wire Company of the evolving magnet design. Fermilab lore, to the Northwest to wove the wire into 23-strand, flat Having previously served as buy niobium-titanium from Wah Rutherford cable which was wrapped in Kapton insulatingmaterial. Above Fermilab's business manager, Chang. "How much is it by the ton? " right: Paul Reardon, right, at a 1974 Reardon played a central role in Reardon is supposed to have asked. conference in Illinois. Opposite left: putting together the collaboration Strauss remembers him explaining, The "Fermilab Kit" for making between the laboratory and the "If we order it by the pound, they'll superconducting wire comprised a manufacturers of superconducting never learn how to make it in quan- copper can filled with 2100 niobium- alloy, of wire and of cable to produce tity." That early decision to buy a titanium rods in hexagonal copper the materials the project required. large amount of niobium (an initial capped with a tubes (foreground), Orr sees Reardon as another of pounds) proved tailpiece and a nose piece. Employees order of about 15,000 of Intermagnetics General Corporation Wilson's strategic choices, another significant in defining the relation- assemble the kit. Opposite right: A person with the right skills at the ships Fermilab established with the Fermilabmachinist winds supercon- right time, a man with "organiza- companies that made the alloy into ducting cable to form the outer shell of tional brilliance and guts. He didn't superconducting wire. a Doubler magnet coil. mind gambling a little with the taxpayers' money when he believed it would mean substantial benefits FROM MINE TO MAGNET in the end." Reardon's gambles usually paid off for Fermilab. Fermilab requested delivery of the Niobium-titanium is an alloy alloy from Wah Chang as straight 24- formed at high temperatures by inch rods, an eighth of an inch in melting in a vacuum with an electron diameter. The rods were the first beam. In 1974, when Fermilab first piece of the Fermilab Kit, which con- went looking for superconducting sisted of a "billet" of 2100 niobium- alloy, the Teledyne Wah Chang titanium rods inserted into hexago- Albany Corporation in Oregon was nal oxygen-free, high-conductivity the major supplier of niobium- copper tubes with round bores, all titanium in the United States-and packed into a 10-inch diameter cop- the Laboratory was virtually the only per "can." Nose and tail pieces were buyer. Strauss and Reardon once welded onto the can. The niobium- constructed a bar chart showing that titanium rods came from Wah Chang. Fermilab had bought 95 percent of The Small Tubes Products Company all the niobium-titanium ever made the hexagonal copper tubes.

18 SPRING 1993 I m .f

The Phelps-Dodge Company fur- of the insulating material Kapton. treatments, and "cold-working," nished copper for the cans, which Tollestrup had discovered that wrap- drawing the wire into ever-finer were made by the Janney Manufac- ping with Kapton not only elimi- diameters. No single step is more turing Company. nated short circuits in the cable but crucial in determining the critical Fermilab bought all these kit insulated the superconductor against current than the heat treatment the materials for delivery to the wire thermal transference that led to wire receives. How hot should the manufacturers, whose task was to quenching. Both Fermilab inven- wire be heated? For how long? At push and pull each 10-inch billet of tions-keystoning and the Kapton what wire diameter should the heat copper-tubed niobium-titanium into wrap-played significant parts in the treatment occur? Each wire company a strand of superconducting wire 27 success of the Doubler magnets. had its own proprietary recipe. thousandths of an inch in diameter. New England Electric Wire deliv- Fermilab dealt with four manu- Each strand would thus contain 2100 ered the cable to Fermilab's Magnet facturers of superconducting wire- filaments of copper-coated niobium- Fabrication Facility for winding into Magnet Corporation of America, titanium superconductor. Theoreti- coils for magnets. Each magnet used Supercon, Airco and Intermagnetics cally, each billet would produce 110,400 feet of wire, twisted into General Corporation (IGC). The first 220,000 feet of superconducting wire. 4,800 feet of cable. The 796 dipole orders gave only a few billets to a In practice, Fermilab paid a premium magnets and 224 quadrupoles in the manufacturer to make into wire. for any usable lengths over 210,000 Doubler used enough wire to circle Fermilab would test it, rejecting wire feet that met specifications. the earth 2.3 times, says contracts below a certain level of performance. After the wire had been tested for manager Lawrence Vonasch. In ad- The vendors' early efforts yielded dimension and superconducting dition, prototype and experimental wildly erratic results. As a company's properties, it went to the New En- magnets used millions more feet of performance improved and the needs gland Electric Wire Company, where wire. of the magnet program increased, it was formed into flat 23-strand "We had learned very early," says Fermilab furnished more billets. By Rutherford cable. Fermilab magnet Larbalestier, "that the properties of the project's end in 1982, IGC-the builders worked with the cable the conductor determined the remaining wire vendor-was process- manufacturer to develop tooling and properties of the magnet." The ing 150-billet orders into highly uni- methods to "keystone" the cable, process of making 10-inch billets into form wire. slightly changing its shape to fit the 0.027-inch wire takes many steps, Close communication between curve required by magnet design. To including an initial extrusion into Fermilab and the manufacturers the finished cable they added a wrap two-inch diameter rods, various heat influenced the success of the

BEAM LINE 19 working relationships that evolved. These decisions had important and controversial consequences, worth examining for their effect on the success and the limitations-of Fermilab's major procurement of superconducting wire in creating and encouraging the superconducting wire industry in the United States. The greatest cost component in Above: Billets at Intermagnetics General Laboratory-industry collaborations, producing superconducting wire is Corporation (IGC), manufacturer of most says physicist Lundy, who put the cost of the alloy. It was of the wire for the Energy Doubler. Each together and ran its mass-production expensive-about $100,000 a ton 10 inch billet yielded about 200,000 feet assembly line for superconducting when Fermilab began buying it in wire, on of 0.027 inch superconducting 1974. For large corporations with spools in background. Opposite: IGC magnets. Wisconsin's Remsbottom, employee winds superconducting wire a skilled hands-on veteran in the deep enough pockets to assume the onto a spool. superconducting field who, says level of financial risk required to buy Lundy, "knew as much about how to large quantities of alloy, the Doubler make superconducting wire as represented a relatively limited anyone in the world," spent most of market that did not justify the his time on the road, traveling from necessary investment in research and Wah Chang to IGC to New England retooling. They just weren't Electric Wire and back again. "If you interested. Smaller, specialized were a Fermilab vendor, you knew companies that did find the Doubler that every two weeks or so, Bob would market worth pursuing lacked the show up." Often Lundy, who was financial resources to buy large himself a practical and inventive quantities of alloy. From Fermilab's engineer as well as a high-energy point of view, the Laboratory's physicist, accompanied him on these purchase of alloy helped the fledgling trips. "They let me in because I was industry by assuming one of the with Bob," he says. These personal major financial risks for these small visits provided a direct channel for manufacturers, that operated, recalls the back-and-forth flow of informa- Orr, "on the ragged edge of nothing." tion that helped improve the quality "Sure they took away some of the of the wire. risk," says Carl Rosner, president of IGC, the manufacturer that ultimately supplied most of the wire. ASSUMING THE RISKS- "They also took away most of the AND CUTTING THE PROFIT profit. By refusing to allow us to buy the alloy ourselves, to our own speci- Fermilab's decisions not only to fications, and mark it up, they took purchase the raw materials for the away our major opportunity to make superconducting wire but to require any money on the contract." the wire manufacturers to use the "It's true we didn't have the cash Fermilab Kit were key factors in on hand to buy niobium," he adds determining the nature of the "but with an order from Fermilab we

20 SPRING 1993 could have gone to the bank for a loan. That's how it's supposed to work. " By furnishing kits to the wire manufacturers, Fermilab eliminated many technical variables in an en- terprise in which systematic control of the parameters of superconducting magnets was absolutely crucial to success. But the kits also took away most of the opportunities for the partnership engendered. What business to get egos into play. But vendors to use their own proprietary tradition is more hallowed in science the question is, 'Will the game be materials and methods-and thus than the free dissemination of the played in an honest fashion?' "It's even more of the opportunities to results of scientific investigation? not a trivial thing-simply to under- profit. What commodity is more precious stand," he adds, "In the long run in "Fermilab helped us enor- to a technology-based company than this country, we need a long-term mously, " says Rosner. "They forced hard-won technical secrets? To commitment to understanding." us to accelerate our learning curve in Fermilab scientists, it seemed only Successful companies in the col- superconducting technology. But our natural and ethical to share what laboration had the motivation to in- experience making wire for the Dou- they learned about superconducting novate and experiment and invest bler should have positioned us as a wire with the world. To the wire resources to supply the materials to world leader in superconducting makers, it seemed like giving away build the world's highest-energy par- technology." Instead, he believes, the farm. From their point of view, ticle accelerator, and in doing so they Fermilab's refusal to allow vendors the scientific community simply built a new industry. High-energy to profit left U.S. superconductor handed foreign firms a state-of-the physics did not invent MRI, but it did manufacturers like IGC ill equipped art recipe for making supercon- push superconducting technology to compete in the world market that ducting wire, effectively eliminating out of the nest so that when MRI took off in the 1980s with the advent the leg up that U.S. companies had came along, the industry was ready of magnetic resonance imaging. gained from their fast and arduous to fly. For the future, we can't predict Maybe so, says Bruce Chrisman, scramble up the learning curve. the exact flight plan, but we can be Fermilab's Associate Director. "But If "The Case of the Superconduct- sure that superconducting technol- if we had let those guys mark up the ing Wire" raises difficult questions, ogy has just begun to soar. In the niobium, it would have sent the cost it also shows that science and indus- words of the late Robert Marsh, of of the Doubler up so high that DOE try can find common ground where Teledyne Wah Chang, still the would have told us to forget it. The both can thrive. Although it didn't world's largest supplier of supercon- Doubler would never have been built, work perfectly, the collaboration ducting alloys, "Every program in and there wouldn't be any market to between Fermilab and the supercon- superconductivity that there is to- talk about today." ducting technology industry did in- day owes itself in some measure to deed work. the fact that Fermilab built the Asked why, Wisconsin's David Tevatron and it worked." WHY IT WORKED Larbalestier says, "I think it came down to honesty-good old- 0 Another thorny issue in this rocky fashioned intellectual honesty. In all marriage between science and the organizations, there were people commerce concerned who would who could focus on the things that have custody of the information that were real. It's all too easy in this

BEAM LINE 21