"Great Gravity" is featured every edition of God & Nature Magazine, and tells the story of BNL physicist Bill Morse's journey through the world of muons and quarks, colliders and bubble chambers, with the heart of a committed Catholic and longtime-teacher of Sunday school. Read the first post in this series here.
BNL 1976 – 2000 (Part 1)
by Bill Morse
I came to BNL in June 1976. BNL had built the AGS (Alternating Gradient Synchrotron) accelerator in the 1960s. The AGS accelerates protons through 28 billion volts so they are going very close to the speed of light. When the proton hits a target, which it sees as neutrons and protons, it produces mass by E=mc2 (as you may recall, energy equals mass times the speed of light squared, which means the more energy the protons have when they hit the target, the more mass—matter—will be produced in the collisions). This is the opposite of a nuclear reactor, by the way, which changes matter into electrical energy. At the AGS, scientists turn electrical energy into matter, and anti-matter. We create neutrons and anti-neutrons, muons and anti-muons, etc. A beam-line then picks out the particles which you want to study.
At BNL I would be working in a collaboration led by Professor Bob Adair from Yale University and Larry. Larry was a whiz at electronics; he was one of the driving forces in the new electronic detectors which were rapidly making the bubble chamber obsolete. Bob was a real “physicist’s physicist”—he just knew everything there was to know about the weak interaction, and I had decided that the weak interaction was much more interesting than the strong interaction, which is what I had done my thesis research on. They had proposed an experiment to the AGS Physics Advisory Committee (PAC), which had approved it. Since the end of World War II, physics research facilities too large for a single University are built at the National Labs. University professors such as Bob then make proposals for experiments which use these facilities, such as the AGS.
I worked on several weak interaction experiments at the AGS in the late 1970s into the 1980s. The last one, called E845, was to search for a rare result from these mass-creating collisions, a then-only-theorized type of particle decay, called a neutral K-meson decay. Particle “decay” is not your average kind of decay. This term refers to the spontaneous process whereby one elementary particle will transform into other types of elementary particles. The particles we were creating in the AGS started off with very high energy and would be therefore unstable in the low-energy environment of our world—so immediately after being created, they transform into particles that have less energy and are more stable. What we were looking for is a unique type of decay that theory told us would only happen once in every ten billion decays.
Now, the problem was this: Sometimes one kind of decay looks an awful lot like another kind of decay. When you’re sifting through millions and billions of data points and the unique one you’re looking for might be masked by a more ordinary type of data that looks just like it, then you might be looking for a very long time.
Another interesting occurrence around this time was the fact that a competing group of scientists at Fermilab, near Chicago, proposed a more ambitious experiment that was looking at the same decay mode we were studying. The race was on. However, we discovered the problem of this “background” data first, since our experiment came online first. Some of the folks at Fermilab invited us to a workshop to give a talk about our results. We described the background to them. This took away some of our competitive advantage, as they could now study how to minimize this background for their detector.
You may ask why we went to their workshop and described the background. Of course, we were in competition with them, but the real competition is with Nature. We would prefer that we beat both them and Nature, but we would greatly prefer that one of us beats Nature rather than Nature winning. Nature won this time: the background got in the way of what we were looking for.
Another collaboration began thinking about doing the same physics by measuring the neutral K meson decay to a neutral pion and a neutrino and anti-neutrino. Although technically much more challenging, it doesn’t have the “Greenlee” background, named after our post-doc Herb Greenlee, who did the definitive study of this background. Herb got a Physicist job at Fermilab after our experiment was completed. It looks like a sensitive experiment on this decay will be done in the future at the Japanese National Elementary Particle Physics Lab. Although we didn’t make a big discovery in our experiment, I’m proud of the work that we did, as it led the way to what will hopefully be a discovery at the Japanese National Lab.
In 1989 I was in a quandary about what to do next. I was in a car pool with Derek Lowenstein, the chairman of the AGS Department. He asked me “Why don’t you look into the muon g-2 experiment.” I didn’t want to get involved with the muon g-2 experiment. Let me tell you what it is and then what happened.
(Stay tuned for Part 2 of Bill’s BNL journey in Fall 2014!)