Donald Arthur Glaser, a professor of physics and of molecular and cell biology at the University of California, Berkeley, and the inventor of the bubble chamber, for which he received the Nobel Prize, died at his home in Berkeley on 28 February 2013.
Glaser was born on 21 September 1926 in Cleveland, Ohio, and grew up there. After high school he attended the Case Institute of Technology (now Case Western Reserve University) in Cleveland; he earned his BS degree in physics and mathematics in 1946. While he was a college student there, he also played the viola in the Cleveland Philharmonic Orchestra. He then went to Caltech, where he earned his PhD in 1950 as a student of Carl Anderson. His thesis research was a cloud-chamber study of the momentum spectrum of high-energy cosmic rays at sea level. He joined the University of Michigan physics department faculty in 1949 to work with Wayne Hazen on cosmic rays.
In those days, the only detectors for particle-physics studies that provided a visual image of the events were nuclear emulsions and cloud chambers. At Michigan, Glaser conceived the idea of the bubble chamber as a device that could be used at particle accelerators and, compared with the cloud chamber, could provide better images of particle interactions and trajectories.
The basic idea was to have a liquid under pressure, then to suddenly drop the pressure so that it was above the boiling point (superheated); the ionization of the fluid molecules by a charged particle passing through would then trigger bubble formation, and the bubbles would record the particle’s track. It was, of course, necessary to properly time the pressure drop, the passage of the charged particles, and a photographic flash within milliseconds to obtain the photograph of the particle tracks. Glaser’s original chambers, created in 1952, were thumb-sized Pyrex glass cylinders filled with diethyl ether. A popular myth is that he got the idea for the bubble chamber by observing the bubbles form and rise in a glass of beer, but Glaser denied that. He also later learned that Enrico Fermi had “proven” that the bubble chamber would not work.
Glaser soon built a 15-cm propane bubble chamber that he took to the Brookhaven National Laboratory with graduate student David Rahm in 1954. Donald Meyer and Martin Perl joined them there, and they used Glaser’s chamber to study pion physics at the 3-GeV Cosmotron. Perl went on to receive the Nobel Prize in Physics in 1995 for the discovery of the tau lepton.
The 6-GeV Bevatron at the Berkeley Radiation Laboratory was completed and began operating in 1954; Glaser and his Michigan group built a 30-cm xenon bubble chamber with which they studied the production and decay modes of kaons at the Bevatron in 1959. Among his group were Byron Roe, Jack van der Velde, George Trilling, and Dan Sinclair. Also in 1959 Glaser, followed by Trilling, joined the physics department faculty at the University of California, Berkeley. A year later he was awarded the Nobel Prize in Physics; at age 34 he was among the youngest Nobel laureates.
The bubble chamber became a dominant tool for elementary-particle physics research during the 1960s and 1970s. Luis Alvarez at Berkeley built on Glaser’s bubble-chamber concept; he constructed large liquid hydrogen bubble chambers, which were ideal for studying fundamental particle interactions because the target particles in the chambers were only protons. Hydrogen bubble chambers were employed at the next generation of accelerators, including the Brookhaven and CERN proton synchrotrons of about 30 GeV. For his development of the hydrogen bubble chamber, Alvarez was awarded the Nobel Prize in Physics in 1968.
Bubble chambers contributed greatly to the understanding of elementary-particle interactions and to the discovery of a plethora of particles and resonant states. Of course, the physics results required the analysis of the bubble-chamber photographs, which was done by teams of manual scanners. Within the past 30 to 40 years, though, totally electronic detector matrices have evolved; high-density multiwire arrays and other devices have replaced the bubble chamber, although some groups searching for dark matter have recently adopted the bubble chamber as their search detector.
In 1961 Glaser turned his attention from elementary-particle physics to molecular biology. He had always had an interest in the biological sciences, and he preferred to work by himself or in small groups rather than on the large teams that bubble-chamber programs had become. As a molecular biologist, he worked in Berkeley’s virus laboratory, where he studied bacteria, bacterial viruses (phages), bacterial evolution, and regulation of cell growth. He also studied how skin cancer develops in mammals. In 1971 he joined with two colleagues, Ronald Cape and Peter Farley, to found Cetus Corp, the first biotechnology company to apply the new discoveries in molecular biology research to medicine and agriculture. In 1983 Kary Mullis, a researcher at Cetus, pioneered the polymerase chain reaction, for which he received the Nobel Prize in Chemistry in 1993.
In the 1980s Glaser turned his attention to neurobiology, another of his long-term interests. He spent a semester at Edwin Land’s Rowland Institute for Science in Cambridge, Massachusetts, where he undertook psychophysics experiments in human vision to understand how the brain processes visual indicators of motion. At Berkeley he continued his study of the human visual system, including developing computational models that have yielded descriptions of the perception of motion and depth.
Glaser was a remarkably creative, productive scientist who was always interested in the problems and puzzles of nature. His move from particle-physics detector technology to neurobiology illustrated his broad range of talents and interests.
