Michael Witherell, from the the University of California, Santa Barbara, will succeed John Peoples as director of Fermilab on 1 July.
The search for a new Fermilab director began last year, when John Peoples announced his intention to step down on 30 June 1999.
Michael Witherell earned his PhD at Wisconsin in 1973. He was assistant professor at Princeton from 1975 to 1981 and then moved to the University of California, Santa Barbara, where he was appointed professor in 1986.
His work in the 1980s on a Fermilab charm experiment brought him the prestigious W K H Panofsky Prize in 1990. He was elected to the National Academy of Sciences last year. Since 1993 he has been working on the design and construction of the BaBar experiment at the Stanford Linear Accelerator Center, SLAC.
Over the past three years, Witherell has chaired the High-Energy Physics Advisory Panel (HEPAP), which advises the US Department of Energy on funding for particle physics.