Researching the glue that holds the universe together

Sometimes I think I’m a little too focused in these column on the practical applications of recent scientific research. That’s understandable, since it’s through technology and new ways of doing things that science impacts on our everyday lives.

But underpinning all scientific advances is basic research: research conducted, not to enable us to make a better mousetrap, but to help us gain a better understanding of how the universe works.

A case in point: the research of Dr. Garth Huber, a physics professor at the University of Regina.

Dr. Huber’s work is focused on subatomic particles—which means I’d better do a quick recap of what we know about these wee beasties.

Atoms are made up of smaller particles, specifically protons (positively charged) and neutrons (no charge) in the nucleus, and electrons (much smaller and negatively charged) surrounding the nucleus. If you’re of a certain age, you may think those are the smallest particles we know of. Once that would have been true, but no longer.

In the 1960s scientists realized that there are even smaller particles, called quarks and leptons, that are truly (as far as we know now) elementary. There are six types of each, each with a corresponding antiparticle.

Quarks are almost always found in pairs or triplets with other quarks and antiquarks, producing larger particles called hadrons. The six quarks are called up, down, charm, strange, top (or truth), and bottom (or beauty). Protons and neutrons—and hence, all ordinary types of matter—are made up of up and down quarks: the up quark has a charge of +2/3 and the down quark has a charge of -1/3. A proton consists of two ups and one down, giving it a charge of +1, while a neutron consists of downs and an up, whose charges cancel each other out.

The best known lepton is the electron; the other five are the muon, the tau particle, and three matching neutrinos.

Other particles carry the forces through which particles interact with each other: specifically, gravitation, electromagnetism, the strong nuclear force and the weak nuclear force. Among these, it’s the strong nuclear force that binds protons and neutrons into an atomic nucleus—it’s the glue that literally holds everything together. And it’s this glue that Dr. Huber has been studying, in the form of the “pion,” or “pi meson.”

“The pion is usually pictured as a relatively simple system consisting of one quark and one anti-quark,” Dr. Huber says. But the precise structure isn’t well understood, for a couple of reasons: one, the pion, obviously, is incredibly small, and two, it has a very very very very short lifetime: on average, 26 billionths of a second.

To better understand pion structure, Dr. Huber and a group of 52 other scientists from more than dozen institutions around the world designed an experiment to take a snapshot of one. The work was carried out in 2003 at Thomas Jefferson National Accelerator Facility in Newport News, Virginia. Electrons were fired into a liquid hydrogen target, where they interacted with a cloud of virtual pions surrounding the hydrogen nucleus (a single proton). The escaping charged pions and scattered electrons were then detected at precisely the same moment.

Dr. Huber and his colleagues have been analyzing the data since then to develop a “numerical snapshot” of the pion at the instant of scattering. Last month their article was published in the prestigious journal Physical Review Letters. Dr. Huber is currently involved in plans to conduct additional experiments at Jefferson Lab.

Among those using the published data will be fellow U. of R. physics professor Dr. Randy Lewis, whose team is using something called Lattice Quantum Chromo-Dynamics to predict the properties of subatomic particles such as the pion. By comparing their theoretical predictions with the experimental measurements obtained by Dr. Huber and his team, Dr. Lewis’s team can refine our understanding of the subatomic glue that literally holds our world and everything in it together.

(Well, not “our” understanding, precisely. Ther title of the article published by Dr. Huber and his colleagues certainly puts me in my place, understanding-wise: it’s called “Determination of the Pion Charge Form Factor at Q2 = 1.60 and 2.45 (GeV/c)2,” to which my natural response is, “Hey, how about them Roughriders?”)

You can’t get much more basic than research into the underpinnings of the universe.

One might, in fact, call Dr. Huber and his colleagues “pion”eers.

If one were inclined to bad puns, that is.

Permanent link to this article:

Leave a Reply

Your email address will not be published.

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Easy AdSense Pro by Unreal