High Energy Physics (HEP) began at UC Davis in 1967. The first faculty was Richard Lander. Shortly thereafter David Pellett was recruited, and an experiment was begun in collaboration with others at what is now the Lawrence Berkeley National Laboratory. There was no extramural funding at that time, and Lander and Pellett commuted to Berkeley to carry out what was then called a "counter experiment," so named because it involved particle counters and other electronic detectors such as wire spark chambers, the latter now "ancient history" devices. The other kind of HEP approach was called a "bubble chamber" experiment, since the technique was to photograph trails of small bubbles left in the path of elementary particles as they traversed a large volume of superheated liquid hydrogen. That instrument, too, has also long since been retired from the field – it is rate limited, and the interactions of interest today occur far too frequently for a bubble chamber to be useful.
The bubble chamber was in its heyday at the time, however, and while the counter experiment was going on, plans were made to use the "startup" funds to build instruments to allow the scanning and measurement of such photographs. This technique allowed most of the work (scanning and measuring the photos) to be done on campus, an important advantage to a small group without funding that would allow research physicists and graduate students to reside at distant accelerator laboratories.
At about that time, Philip Yager was recruited to the group and assigned a basement office in Young Hall. Shortly thereafter the first extramural contract with what was then the Atomic Energy Commission (later ERDA and now the Department of Energy) was obtained. Funding allowed the recruitment of Winston Ko as the first postdoctoral researcher, as well as support of graduate students for full time research. For the next several years, the group carried out bubble chamber experiments, studying the properties of the many new particles, called "resonances," that were being discovered at that time. The group became a world leader at the time in the study of what Richard Feynman had dubbed "inclusive reactions." Feynman's approach allowed the inference of the nature of fundamental forces from the study of only one or a few of the many particles emanating from an interaction. This bubble chamber work made use of the accelerators at Berkeley and Brookhaven, and later at Fermilab when that laboratory began operating in the 1970s. Later a hybrid experiment was carried out at Stanford using a combination of the bubble chamber and electronic apparatus. That was the last of our bubble chamber experiments. The work thereafter centered on electronics experiments, which by then required collaborations by several institutions in order to have enough personnel to carry them out.
The switch back to "counter" experiments in 1979 saw a division in the interests within the group, as Professor Yager had recently joined with outside groups to develop an experiment at Fermilab studying the production of neutral K mesons and L baryons. His Fermilab research became exclusively "fixed target," where high energy particles extracted from an accelerator impinge on a stationary target and the products of the collision are recorded in downstream detectors. With a research physicist and students, he concentrated on a detailed study of the production and decay of charm particles. This program has to a considerable degree written the book on charm.
The other approach, colliding two beams of particles from opposite directions, increasingly occupied the rest of the group. With Winston Ko (by now a professor) and two research physicists on board, we joined in a successful proposal to study electron-positron interactions at Stanford's PEP accelerator, the highest energy machine of its kind in the world. Here we hoped to see evidence of the new physics phenomenon that we knew had to exist at some high energy, the top quark. As it turned out, that important object had to await the running of the Tevatron at Fermilab, and was seen only in 1996. The PEP data were still quite interesting, though, and allowed a much better understanding of a number of phenomena, including collisions of two high energy "particles" of light – photon-photon interactions. The Davis group was in the forefront of this kind of study. After PEP, we moved onto the TRISTAN e+e- collider of the Ko Energy Kenkyusho (KEK) in Japan, which then had the highest energy in the world, twice that of PEP.
Naturally, since the forefront accelerators we used were located elsewhere (Palo Alto, New York, Illinois, Japan) and "our" computer was in Berkeley, travel was very much in order, and often a challenge. Before the current Sacramento airport was completed, the only service was out of the Executive Airport, and it was pretty exclusively limited to Pacific Southwest Airlines. Not bad if your destination was in California. With the new field, our range was extended, but getting to the airport involved using the Elkhorn Ferry. When the Sacramento River was too high this would lead to a race east along the levee road to cross at Broderick, then up old 99 and back west to our "international" airport. The university's excellent auto and truck fleet served us for more local travel. The high point of summer trips to Lawrence Berkeley Lab was on the north edge of Vacaville, where the odor from the onion drying sheds would cure any summer cold in seconds. The UC Davis experiment at the Stanford Accelerator coincided with the gasoline crisis. Topping off the vehicle at the central garage would yield exactly two round trips, and more than once, slightly less than two!
The period from 1971 to 1976 represented the time the group truly established its reputation in the high energy community. We were publishing a paper every quarter in Physical Review Letters on inclusive reactions. It was quite remarkable that during that period there was not a single high energy theorist on the UCD faculty! There was an infectious excitement about building a strong program from scratch, which served our students well. Several examples can be cited. In 1977 (20 years ago!), we, particularly our graduate student Joe Erwin, made the first application of the Intel microprocessor to control the automatic scanning and measuring of bubble chamber pictures. Joe went to industry after graduating to further pioneer microprocessor applications. During this period another graduate student, Richard Kass, did his thesis work on charged and neutral particle productions from 400 GeV/c proton proton collisions. He is now a full professor at the Ohio State University. Roger McNeil, who did his thesis on the photon structure function, is now an associate professor at Louisiana State University. Gary Shoemaker wrote his Ph.D. thesis on our final bubble chamber experiment at Stanford and is now a full professor at California State University, Sacramento. John Pearson is a group leader at Lawrence Livermore Laboratory. Steve Gourlay was just appointed head of the superconducting magnet group at Lawrence Berkeley Laboratory. These magnets are crucial to the Large Hadron Collider, the biggest, newest accelerator, now under construction in Europe. David Stuart is now a research associate at Fermilab in charge of the highly successful silicon vertex detector of the CDF experiment. He did his thesis work on the forward-backward charge asymmetry of quark pairs produced at the KEK e+e- collider TRISTAN. Many other students are equally engaged in industry, research and academic positions, but that would be another story.
All in all, it was a great time!
| Previous Article | Home | Next Article | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||