Antimatter Breakthrough: Big Batch Created in Lab

Robert S. Boyd
Miami Herald

September 20, 2002

Scientists announced a major breakthrough in their long struggle to understand the weirdest stuff in the universe—antimatter, the mirror image of ordinary matter.

A team of European physicists reported the creation in a Swiss laboratory of at least 50,000 atoms of antihydrogen, the fictional fuel in Star Trek's imaginary "warp-drive."

It was the first time that a significant quantity of antiatoms, the looking-glass cousins of normal atoms, has been produced on Earth, according to a report published on the Internet by the British journal Nature.

Antimatter is composed of electrons and protons, the raw materials of atoms, but with a whopping difference—the electrical charge.

Battery Terminals

Like poles on a battery, a normal electron has a negative charge, while a proton is positively charged. In antimatter, however, the charges are reversed. The electron's antimatter counterpart, known as a positron, carries a positive charge. The antiproton has a negative charge.

Ordinary hydrogen, the simplest and most abundant element in the universe, consists of one electron orbiting one proton. Antihydrogen has one positron and one antiproton.

When matter and antimatter collide, they annihilate each other and emit a burst of electromagnetic energy. The Reagan administration's "Star Wars" project briefly toyed with the idea of using this force to destroy incoming Soviet missiles, but abandoned it as unworkable.

Since the first positrons (antielectrons) were detected in 1932, thousands of physicists have been laboring to create or collect antimatter, using the world's mightiest nuclear colliders, orbiting spaceships, and balloon-borne detectors.

"We spend all day making antimatter," said Nigel Lockyer, a physicist at the Department of Energy's Fermilab near Chicago, which churns out 50 billion antiprotons in an hour.

"Every year we check the latest data, hoping to find the first ambassador from the antiworld," said Jonathan Ormes, a physicist at NASA's Laboratory for High Energy Astrophysics in Greenbelt, Maryland. Ormes' group uses high-flying balloons to trap cosmic rays, looking for antimatter particles zooming in from outer space.

A NASA antimatter detector is scheduled to be boosted up to the International Space Station next year.

Researchers will be searching not only for antihydrogen, but also for larger antiatoms, such as antihelium, anticarbon, and antinitrogen.

Although antimatter sounds like science fiction, antielectrons are used every day in hospitals and clinics around the world. They are the key to the positron emission tomography, or PET, scans employed since 1950 to observe what's going on inside a human brain.

Positrons are found in cosmic rays and can be produced on Earth by bombarding ordinary atoms with protons, causing them to break up and emit various particles, including these useful bits of antimatter.

Other subatomic forms of antimatter, including antiquarks and antimesons—particles even smaller than protons—have been created in antimatter "factories" at Fermilab; at Stanford University in Stanford, California; near Osaka, Japan; and at the European Organization for Nuclear Research, known as CERN, in Geneva.

Moving Too Fast

A small number of antihydrogen atoms were produced in the mid-1990s at CERN and at Fermilab, but they were moving extremely fast and vanished before they could be analyzed.

This year's big new batch of antihydrogen was created at CERN by the ATHENA Experiment, a collaboration of physicists from 11 European universities.

Positrons and antiprotons were cooled to about 450 degrees below zero Fahrenheit to slow them down, and then combined in a magnetic trap. The magnetic force kept them briefly from colliding with the walls of the trap and obliterating themselves.

Their lives were short. Even at this temperature, antihydrogen lasts less than a hundredth of a second before it hits the wall, according to Jeffrey Hangst, physics coordinator of the ATHENA project, from the University of Aarhus at Denmark.

Before the antimatter vanished, it left a distinctive signature in a particle detector, demonstrating that it was antihydrogen, Hangst said.

Because it is so difficult and expensive to create and store antiatoms, scientists say it is impractical to use them as a power source.

All the antimatter produced at CERN in a year would light a 100-watt bulb for only 15 minutes, Hangst said.

Nevertheless, physicists expect the study of antimatter will help them understand the fundamental nature of matter and what happened during the first few seconds of the universe.

Copyright 2002 Miami Herald