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Past Winner
2008 E.W.R. Steacie Memorial Fellowship

Carl E. Svensson


University of Guelph

Carl E. Svensson
Carl E. Svensson

Carl Svensson is searching for a previously unknown force of nature, and if he finds it, he will stand some of the current laws of physics on their head. That’s because the force he’s looking for behaves in a fundamentally different way from the ones we already know: their effects do not depend on the direction of time.

Dr. Svensson has carved out an enviable reputation in the rarefied world of subatomic physics for both his experimental work and his leadership in designing and building the tools needed to probe the inner workings of atoms. His contributions have earned him an NSERC E.W.R. Steacie Memorial Fellowship.

The four forces we currently know about – gravity, electromagnetism, and the strong and weak nuclear forces – behave symmetrically, that is, if time were reversed they would cause exactly the same effect on objects. For example, the law of gravity would still make the earth orbit the sun in exactly the same path if time were reversed, just in the opposite direction. The force he is looking for, which exists only in theory at the moment, flouts that rule.

Part of the reason Dr. Svensson believes these unknown forces exist has to do with the fact that the universe is filled with matter. Anti-matter, composed of positively charged electrons and negatively charged protons, can be created in the laboratory but does not appear to exist in large quantities in the universe. If the universe is governed only by the four currently known forces, however, he says the Big Bang should have created equal amounts of matter and anti-matter.

While most people are content to simply accept the fact that there are no roving pieces of anti-matter floating around to annihilate matter that we hold dear, Dr. Svensson wants to understand why this is true. “Looking at the universe and seeing that it is all made of matter with almost no anti-matter, tells us that these forces have to be out there. We just haven’t found them yet,” he says, adding that some of the theoretical frameworks developed by physicists to explain all forces also predict the existence of more forces.

“If they do exist, there are very clear predictions as to some of the phenomena that will be produced because of those effects,” he continues. “If these theories are right, there may, in fact, be only one force, and the things that we think of as the strong nuclear force and electromagnetism, for example, may actually just be different aspects of the same interaction.”

Not surprisingly, the effects of this unknown force are not readily observable. The most promising option is to look for a phenomenon called an intrinsic electric dipole moment (EDM) in an atom, something that cannot exist under the current laws of physics. Normally, we think of the centre of the group of electrons in an atom as precisely in the centre of that atom’s nucleus. An EDM would correspond to those two centres being slightly separated.

As often happens in subatomic physics, Dr. Svensson’s quest for new knowledge led to the need to design and build new tools. That meant playing a lead role in the design and construction of TIGRESS (TRIUMF-ISAC Gamma-Ray Escape Suppressed Spectrometer), the best facility of its kind in the world.

Housed at TRIUMF (the Tri-University Meson Facility, Canada’s national laboratory for nuclear and particle physics research in Vancouver) and built with the help of more than a dozen institutions, TIGRESS is effectively a giant microscope that allows scientists to study the nucleus of an atom. It detects gamma rays (very high frequency light) with unprecedented sensitivity, measuring not only the energy of the light but pinpointing their direction of travel as well.

Started in 2003, TIGRESS will be completed in 2009, but enough components have been up and running since 2006 for research to be in full swing. “It’s very much a collaborative effort,” Dr. Svensson says. “It takes quite a number of people with different expertise to put such a facility together.”

The fact that he helped build TIGRESS doesn’t grant him any special privileges. “Beam time” at TRIUMF is in high demand from physicists around the world, and he has to justify his proposed research to an evaluation committee along with everyone else.

Justifying his research was not hard in this case – the EDM experiment has been described as one of the most important experiments planned at TRIUMF in the coming decade. If Dr. Svensson succeeds in finding experimental evidence of new forces, it will revolutionize physics and help us understand the fundamental process of how matter originated in the universe.

His work has already led to significant advances in technology that can peer into an atom’s inner workings. But, despite the fact that TIGRESS is tops in its class, continued progress in physics requires researchers to continue pushing the technology envelope. “We build new detectors, and we answer some of the questions that existed when we designed them, but we inevitably create more questions than we answer,” he says. “That leads to new developments in theory, which point us in the direction we should develop the technology. It’s a continuous cycle.”