Humans have always sought to understand the world around us in the simplest possible terms. The realization, over a hundred years ago, that the infinite variety of materials we encounter in everyday life can be explained in terms of a small number of different kinds of atoms, was a great achievement. Not only did this give us a simple explanation of the great diversity of materials, it also provided a framework for making predictions. A simple analogy is to think of Lego blocks. We know we can build a huge variety of structures even if we start with just a small selection of different blocks, and we can also predict the shapes we will end up with by stacking up various combinations of Legos.
It turns out that the same story is repeated inside the atom. The hundred or so different kinds of atoms we know about can all be explained in terms of just three smaller building blocks; the electron, the proton and the neutron. This magnificent realization tempted us briefly into thinking that we knew everything there was to know, but fortunately this notion was shattered by further experiments that showed that protons and neutrons are themselves composed of even smaller subatomic particles, called quarks.
After many years of experimentation and head scratching our picture of the micro-world is still incomplete. We have pretty good evidence that there are six different kinds of quarks, to which we have assigned the lighthearted names "up, down, charm, strange, top and bottom". We also believe we understand some of the laws that govern the combination of these quarks into larger objects like protons and neutrons. Just as those in everyday life, however, the subatomic laws seem to be full of fine print that is difficult to read and interpret. Given that these laws govern not only the composition of everything in the universe, but also the very creation of the universe itself, it is of considerable interest to try and understand them much better than we do at present. The field of study striving for this knowledge is called elementary particle physics, and has been my playground for the past 12 years.
It's a bit of a paradox, but it turns out that in order to make measurements of something that is very small, like subatomic particles, we need a very large experimental apparatus. In our experiment, which is called CLEO, we use a big ring-like machine about the size of a football field, called a synchrotron, to accelerate electrons and positrons to extremely high speeds. These tiny particles, to which our synchrotron has given an energy equivalent to about ten billion volts, are slammed together in head-on collisions, which in turn produce the quarks we use to study the fundamental laws.
We are used to the notion that very rare items are much more valuable than ones that are easy to find. This is certainly true in particle physics. During most of the collisions in CLEO nothing very interesting happens, however once in a while something useful to our study will occur. Unfortunately, is extremely rare that a profoundly interesting event is produced. It is, of course, the latter case that is of most interest to us. Searching for the most interesting events is like panning for gold. You need to sift through tons of sand to find the tiny gold nugget that makes it all worthwhile. Two things can increase your chances of finding gold: Looking at more sand, and getting a better sifter. In our experiment this is equivalent to creating more collisions (like sand) and building a better apparatus (sifter) to distinguish the interesting collisions from the non-interesting ones. I am presently working on designing and building a better sifter, or "trigger" as we call it, for the CLEO experiment. To better understand the challenge involved you need to know that electrons and positrons collide in CLEO about twenty million times every second. The job of the trigger is to constantly monitor all aspects of the experiment and to distinguish between interesting and non-interesting collisions, and obviously to do so very very quickly.
The punch line of this story is that designing an experiment, building it, and using it to explore the laws of nature is wonderful fun.