Tantalus Recieves Its Place In History
As the thirty year anniversary of the use of Synchrotron Radiation (SR) at SRC for research approaches, a
cornerstone of this technology, the Tantalus electron storage ring, is to become a Smithsonian National
Museum of American History exhibit. The 240 MeV ring, which is less than a mile from Aladdin, has
been used only sparingly since 1987 when the 1 GeV Aladdin facility was fully opened to research.
Ed Rowe stands in front of the birthplace of SR research, the Tantalus Electron Storage Ring.
The story of the storage ring begins with the Midwestern University Research Associations (MURA)
curiosity with particle accelerators. MURA had planned to build a large (12.5
GeV) proton accelerator in
the field across from the current Physical Sciences Laboratory, but in 1964 that project fell through. In
early 1965 the research group began another project to continue fundamental studies of particle
accelerators. This project would include the construction of a small (240 MeV) electron storage ring.
During that same year, The National Academy of Science formed a subcommittee on the use of
synchrotron radiation for condensed matter research chaired by Professor Frederick C. Brown of the
University of Illinois. The subcommittee learned of the storage ring project and knew that electron
storage rings would emit SR during operation. In March of 1966, the two organizations agreed to
cooperate in the construction to achieve their different, but related goals.
During the next two years, the structure of the scientific community that MURA had created drastically
changed. Particle accelerator research funds became scarce, and in 1967 the University of Wisconsin-
Madison absorbed the research center and created the Physical Sciences Laboratory (PSL). Although
many of the scientists from MURA continued working, the mission of the organization changed. The
Physical Sciences Laboratory was to be a service organization for UW-Madison, providing scientific and
engineering research to programs on campus. The budget for PSL did not include completing the
construction of the electron storage ring, so the scientists chose to name their incomplete machine
Tantalus, in reference to the Greek King who was punished with thirst and hunger in view of unreachable
water and fruit.
To survive, the Tantalus project had to be adapted to the ever growing and changing scientific interests of
the time. By late 1967 several SR research scientists had substantial investments in the Tantalus project
and funding was found to complete the first ever dedicated synchrotron radiation source. In early 1968
the ring was complete, and in August of that year, the first data was collected by Dr. Ulrich Gerhardt. By
1973, Tantalus had become an operational extension of the University of Wisconsin-Madison providing a
SR research facility that produced more than 100 journal articles a year, a substantial feat for those days
considering there were only four beamlines in operation until 1974.
As interest for SR research grew, the demand for a brighter light bulb, as current Associate Director Ed
Rowe says, by far exceeded the supply. In 1977 construction of the much larger Aladdin electron storage
ring began and as the new facility prepared for its first users in 1983, the Synchrotron Radiation Center
separated from PSL.
Although Tantalus continued to be available for research while Aladdin was brought up to full capacity in
1987, researchers lost interest in Tantalus as both beam energy, current, and reliability in the Aladdin ring
grew. Research on the Tantalus ring was discontinued at the beginning of 1987 and in late 1993, it
became apparent that Tantalus would be decommissioned and dismantled. This was not a satisfactory end
to the project, in the opinion of the first SRC director, Ed Rowe.
Rowe wanted to save the machine where SR research had started, so he contacted the Smithsonian
National Museum of American History about their interest in acquiring this piece of history. Dr. Paul
Forman, the curator for the Electricity and Modern Physics Collection at the museum responded to
Rowes inquiry. Dr. Forman thought the project sounded interesting, so the two of them began the task of
convincing the museums acquisition committee of the historical importance of Tantalus. After gathering
evidence, it was clear to both Dr. Forman and the committee that this was truly a piece of history worth
saving. Not only was the machine a true innovation in electron storage ring use, but it was an ideal size
for an exhibit, Dr. Forman summarized. Most accelerator research projects of this quality are much too
large for display.
Dr. Forman visited SRC in April and got a chance to see the storage ring operate, maybe for its last time.
It has not yet been determined when or how this piece of history is to be displayed, but Dr. Forman hopes
to have one half of the 3 meter ring, including the RF cavity, dismantled and shipped to the Smithsonian
some time this fall.
When asked when Tantalus would go on display, Dr. Forman said, this exhibit, like most exhibits, is for
posteritys benefit and will not be displayed for some time. Although scientists who use SR radiation
may consider Tantalus history already, one must consider that the current displays include the telegraph
and the first telephone invented by Alexander Graham Bell. These pieces were saved for over one
hundred years before attaining historical status in the eyes of the Smithsonian. While in storage,
Tantalus will share quarters with such distinguished innovations as the Carnegie Van de Graaff
Accelerator and Ed McMillans Electron Synchrotron, until the proper time comes for public display.
Aladdin-Editor Brian Tonner email@example.com