Probing the Quirks of Quarks - Getting Down to Basics (Rensselaer Magazine)

Mirror, mirror: One of the Rensselaer-built Cerenkov detectors shown being installed in the Hall B spectrometer.
Enlarged version of photo.

Probing the Quirks of Quarks

The lab is a complex assembly of high-tech hardware and electronics stretching through an oval underground tunnel almost a mile around. Not so much an atom-smasher as a gigantic electron microscope, the Jefferson Lab offers an unprecedented combination of high energy levels and detailed views of the subatomic realm. With it, scientists can discern fundamental particle structures and effects with unparalleled precision and clarity. Designed with maximum efficiency and productivity in mind, it is the first large-scale electron accelerator that uses superconducting technology to accelerate the electrons, meaning it uses a fraction of the electricity otherwise needed.

Getting Down to Basics

Scientists need such facilities even in times of relative fiscal austerity because the work performed there helps to answer basic questions about the nature of the universe, an inquiry that has been conducted in many different ways from the earliest days of human history. But equally important are the practical applications of such basic research. For example, when J.J. Thomson discovered the "corpuscle," as he first called the electron, he couldn't possibly foresee the revolutionary technologies that would come from putting it to productive use, among them the transistor, computer, television, and laser.

"Quarks" deserve a few words of explanation. You can think of an atom as a kind of miniature solar system, with electrons orbiting a nucleus much as planets orbit the sun. The motion of the electrons gives an atom its overall size, but the nucleus gives each atom its special properties. The nucleus is made up of protons and neutrons, particles that in recent years were shown to have their own subunits. These subunits are the quarks. Quarks are thought to be indivisible, fundamental particles held together by gluons or gluonic force (the terms are used interchangeably).

A definitive quark-based understanding of protons and neutrons, and the nucleus they comprise, will be as important scientifically as the understanding built up since the 1930s of how a nucleus and electrons comprise an atom. For this reason, two quark-related branches of physics are evolving. One branch is in the area of high-energy physics, where particles are accelerated to billions of electron-volts to understand the quark itself. The other is called quark physics, a blend of nuclear and high-energy physics aimed at studying how quarks and gluons make up the protons, neutrons, and nucleus. Jefferson Lab is designed for quark physics.

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