Chemical News | Actualité chimique
Fundamentals
Antimatter Containment: Not Just for Warp Drives Anymore
Maximilien Brice
Experiments to create antihydrogen and hold it in a magnetic trap were run on the antihydrogen laser physics apparatus (ALPHA, left) at CERN. The diagrams above show untrapped antihydrogen atoms annihilating on the inner surface of the ALPHA trap.
Fans of Star Trek’s various TV incarnations will recall the fictional antimatter-powered warp drive, which threatened to catastrophically spill its contents about every other episode. As it turns out, real antimatter can indeed be quite difficult to contain, which is one of the reasons it’s so hard to study. Now, thanks to an international research team of 42 scientists, including 15 Canadians, science is one big step closer to getting a good look at antihydrogen. Since antimatter obliterates itself the second it contacts matter, researchers must use powerful magnetic fields to hold it in place. This works well for charged particles like antiprotons and positrons. Antihydrogen, however, is a neutral molecule, with only a weak dipole moment to hold onto. “You have to make them with very, very low energy,” says Scott Menary of York University, who was part of the team. “That’s the real technical challenge.”
The researchers at CERN (the European Organization for Nuclear Research) managed to create low-energy plasmas of antiprotons and positrons, cooling them to near absolute zero before bringing them together in a vacuum chamber. Only the most lethargic anti-atoms were caught in the magnetic traps. They stayed there until the fields were turned off, at which point the team detected 38 annihilation events, proving that they had caught their elusive quarry. The team is now working on capturing enough atoms of antihydrogen to compare its properties to normal hydrogen. “There’s not really a limit to how long we can hold it,” says Menary. “At this point, it’s not obvious exactly how many we need. But it certainly isn’t millions; hundreds to maybe a thousand should be just fine.”
Earth Chemistry
Ocean Phosphorus Boom Could Have Sparked Animal Life For most of its 4.5 billion year history, the Earth was inhabited by only the hardiest of microorganisms. It was only 580 million years ago that oxygen levels became high enough to support animal life. New research suggests that the trigger for this event may have been fluctuating phosphorus levels in ancient oceans. Kurt Konhauser, a geomicrobiologist at the University of Alberta, and his PhD student Stefan Lalonde, were part of an international team that gathered more than 700 samples of rocks known as banded iron formations (BIFs) spanning almost 3 billion years of earth’s history. By measuring the levels of phosphorus in these rocks, the team was able to infer what levels of the element were like in the oceans that surrounded them. “We thought they were pretty much stable through time,” says Konhauser. “Then we
suddenly saw this big spike, around 700630 million years ago, something we never anticipated.” That spike corresponds to a period known as “snowball earth.” Glaciers almost encircled the planet, grinding down mountains and enriching the oceans with phosphorus from their dust. The extra phosphorus would have caused huge blooms of algae, which in turn would have rapidly raised oxygen levels. “Prior to that there presumably wasn’t enough oxygen in the oceans to allow animals to evolve,” says Konhauser. “That event probably kickstarted the evolutionary process.”
January 2011 CAnadian Chemical News 11