DAVID ROBERT NYGREN
Distinguished Scientist - Lawrence Berkeley National Laboratory
David Nygren's inventions and innovations in radiation detection have transformed research in particle and nuclear physics and cosmology. His ingenious designs, of striking simplicity and unprecedented resolution, have enabled a broad range of measurements, from the imaging of complex events at high luminosity colliders to searches for the rarest low energy phenomena, as well as the observation of very high energy neutrino interactions in the world’s oceans and deep within Antarctic ice.
Dave, with a PhD from the University of Washington, started his scientific career in 1967, as a Research Associate at Columbia University’s Nevis Laboratory, under the direction of and in collaboration with Jack Steinberger, and later with Bill Carithers. At Nevis, Dave observed, and measured, effects of CP violation in the decay of KL mesons. Early in that work he and others at Nevis built what was then the world’s largest multi-wire proportional counter, an important advance in particle-detector instrumentation.
In 1973 Dave left Columbia and joined Lawrence Berkeley Laboratory as a Division Fellow. Soon afterwards, in 1974, he invented the Time Projection Chamber (TPC), an entirely new, distinctive, and extraordinarily powerful device to detect, identify, and track multitudes of charged particles in three dimensions. The first large TPC was the heart of the PEP-4 experiment, operated from 1981-1989 at the SLAC Positron Electron Collider. Since that time, the TPC has been variously developed to become the internationally preferred detector in a wide range of elementary-particle and nuclear physics experiments. Large TPCs were central to the ALEPH and DELPHI detectors at CERN's Large Electron Positron collider (LEP). Between 1989 and 2001, these detectors studied the Z and W bosons and established the validity of the Standard Model of particle physics through a series of precision measurements. Since 2000, the STAR-TPC, at the Relativistic Heavy Ion Collider (RHIC) at the Brookhaven National Laboratory, has studied collisions of matter at high energy density, and probed the fundamental interactions of quarks and gluons. Images of the gold-on-gold collisions from RHIC have graced the front page of The New York Times, as well as several book covers. The ALICE detector, which is used to study heavy ion collisions at the Large Hadron Collider (LHC) at CERN, relies on a TPC to measure these interactions at even higher energy. The TPC has proved to be invaluable not only in experiments where there are frequent, and complex, multiparticle events, but also in rare-event experiments. The TPC in the ICARUS experiment in the Gran Sasso Laboratory (LNGS), in Italy, uses liquid argon in place of gas to measure high-energy neutrino interactions with a beam generated at CERN. Liquid-xenon filled TPCs are now a primary means of searching for WIMP dark matter particles, where the recoil energies are measured in tens of keV. From keVs to TeVs, TPCs are still at the forefront of particle and nuclear physics research, some forty years after their invention.
Dave was named Senior Physicist at LBNL in 1975; in 1986, he became a Fellow of the American Physical Society; in 2000 he was inducted as a member of the National Academy of Sciences. Dave’s work has been honored with acclaim; he has received: the DOE’s E. O. Lawrence Award, 1985, “For the development of experimental techniques in particle physics and especially for the invention of the Time Projection Chamber." In 1998 he was awarded the American Physical Society’s W.K.H. Panofsky Prize, "For the concept, development, and application of the time projection chamber (TPC), enabling unprecedented studies of complex topologies of charged particles produced in high-energy collisions of interest to both high energy and nuclear physics.” In 1995 Dave was promoted to the rare Distinguished Scientist classification at LBNL for his “sustained history of distinguished scientific and technical achievements,” and in 2013 he received the Director's Lifetime Achievement Award, “for Exceptional Achievement.”
In the late 1980s, with the planned Superconducting Super Collider (SSC) under construction, Dave and collaborators pursued a variety of electronics-based approaches to particle detection and measurement. Dave initiated a research path at LBNL aimed at developing smart-pixel arrays. This work led to the LBNL pixel system based on a column-architecture concept, and was realized by a team led by Kevin Einsweiler. Today this system provides precision tracking for the ATLAS experiment at the LHC. Another result of this was a suggestion by Dave for the development at LBNL of fully depleted CCDs. The realization by Steve Holland was a great success and these are now widely used in astronomical imaging and spectroscopy.
In the 1990s Dave pioneered the application of fast waveform sampling and digitization techniques while he was a Distinguished Visiting Scientist at the Jet Propulsion Laboratory, Pasadena, California (1995-1997). His work detecting neutrinos led first to the KAMLAND neutrino detector in Japan and then to his transformation of the ICECUBE array in Antarctica and its spectacular discoveries, noted recently as the “2013 Breakthrough of the Year” by Physics World. A graphic of the array graced the cover of the November 22, 2013 issue of Science.
Dave’s creative particle detection schemes have transformed other fields as well. By turning silicon strip detectors, designed for particle physics, on their ends, he created detectors with superb spatial resolution able to count individual x-rays for medical applications. This low-dose system produces data superior to that of previous methods used clinically in mammographic radiology, thereby sparing women both additional testing and excessive dose. Dave’s concept was later developed commercially in Sweden, and now is the most widely used method for digital mammographic screening in Europe, Japan, Australia, and is currently making headway in the Middle East and North America.
Most recently, Dave has been pioneering new high-pressure xenon-gas detection TPC methods for double-beta decay and dark-matter searches as a member of the NEXT collaboration.
Dave has yet to indicate what will be his next act, something that we all should eagerly await. It is sure to come.