by Sharon Butler

Michael Witherell, a professor at the University of California, Santa Barbara, with a distinguished career in experimental particle physics, has been named to succeed Fermilab Director John Peoples.

Congratulating Witherell on his appointment, Secretary of Energy Bill Richardson noted that Witherell is a leader in his field and will be taking on the directorship of the Laboratory at a time of extraordinary opportunities for new discoveries in the fundamental nature of matter and its forces.

"We here at the Department of Energy look forward to working closely with Dr. Witherell to ensure that the U.S. remains a world leader in particle physics research," Richardson said.

"The Fermilab community is very fortunate to have Mike Witherell for its fourth director," Peoples said, "because, having worked at the Laboratory as an experimenter, he already knows us. The U.S. particle physics community is also fortunate because, as chairman of the High-Energy Physics Advisory Panel, he has guided the formulation of the advice that has shaped the field’s research program. Finally, he is no stranger to difficult choices. As chairman of the 1992 HEPAP subpanel, he led his colleagues to present clear options for the future without ducking the difficult issue of a shrinking budget."

The search for a new director began last year, when Peoples announced his intention to retire on June 30, 1999. Universities Research Association, Inc., which operates Fermilab, formed a committee of respected physicists to canvas the world for candidates. On March 5, URA announced Witherell’s appointment, effective July 1.

URA President Fred Bernthal commented, "With his broad knowledge and experience, Mike is a perfect choice to lead the Lab and the high-energy physics community into the next millennium."

Bernthal added, "We are grateful to George Trilling, chair of the Search Committee, and his committee colleagues for their thorough and conscientious effort in helping us reach this very successful outcome."

When Witherell conducted experiments at Fermilab from 1978 to 1990, he never dreamed that one day he would be the Laboratory’s director. "My career just didn’t seem to be pointed in that direction," he said.

Indeed, since earning his Ph.D. from the University of Wisconsin in 1973, Witherell has pursued an academic career, working at every major particle physics laboratory in the country. He was an assistant professor at Princeton University and then moved to the University of California, Santa Barbara, where he was appointed professor in 1986.

Witherell’s work on experiment E691 at Fermilab from 1983 to 1990 brought him the prestigious W.K.H. Panofsky Prize in Experimental Particle Physics, awarded in 1990, and election to the National Academy of Sciences last year, one of the highest honors accorded a scientist in the United States.

The goal of E691 was to study particles containing charm quarks. The E691 collaboration proposed adding to the existing Tagged Photon Spectrometer, built for the E516 experiment, two components based on newly developed technologies: a silicon vertex detector and a high-speed data acquisition system. The success of this strategy was evident almost immediately: In data from the first five percent of the run, Witherell remembers seeing a charm signal larger than any in earlier experiments. The full experiment identified about 10,000 charm events, while similar previous experiments had collected no more than 100. The higher statistics guaranteed more compelling scientific results than any to date.

In electing Witherell a member in 1998, the National Academy of Sciences noted that his pioneering work in the application of silicon vertex detectors and high-speed data acquisition systems "profoundly influenced all subsequent experiments aimed at the study of heavy-quark states."

Indeed, both technologies are far more advanced now than they were in the mid-1980s and are extensively used at Fermilab. Witherell noted with amusement that E691 used only nine silicon sensors. By comparison, the upgraded CDF detector will have well over 1,000. But some things haven’t changed. Just as the CDF and DZero collaborations are now impatiently awaiting fabrication of their silicon strips at Micron Semiconductor, so Witherell remembers collaboration members back in 1984 flying to England to prod the same manufacturer into hurrying delivery of the new technology.

More recently, Witherell’s research has focused on understanding the source of the asymmetry between matter and antimatter known as CP violation. Since 1993, Witherell has been working on the design and construction of the BaBar experiment at the Stanford Linear Accelerator Center. The experiment, to begin operating this year, will measure the asymmetry in decays of B mesons, particles composed of a B and an anti-B. Although CP violation was first discovered in neutral kaons, scientists expect the effect to be multiplied many times over in certain decay modes of the B meson. With far more data to analyze, physicists hope to gain further insight into the phenomenon.

Over the last three years, Witherell has been chairing HEPAP, which advises DOE on funding priorities for high-energy physics. Witherell was also a member of the recent HEPAP subpanel chaired by Fred Gilman, which was charged with recommending a scenario for an optimal and balanced high-energy physics program over the next decade, with new facilities to address physics opportunities beyond the Large Hadron Collider. When completed, the LHC, currently under construction in Europe, will take over the energy frontier from Fermilab.

Witherell expects his job as director to involve three responsibilities: overseeing this large and diverse laboratory so that operations run smoothly and efficiently; working with the larger high-energy physics community to shape the future direction of the field (an area where laboratory directors play a special role, he said); and winning support from funding agencies and elected officials in Washington.

"The Laboratory is in a strong position," he said, citing the increases in luminosity the accelerator will achieve in Run II, enabling experimenters to accumulate more data than ever before. "In addition, exciting new physics results from past runs have recently been announced." For the long term, though, he recognizes that there will be challenges.

"We will require new facilities to address pressing scientific questions if the field of particle physics is going to remain vital," Witherell said, adding, "I didn’t take this job because I thought it would be easy."