A nickel's worth of foil helps make antimatter

LOS ALAMOS, N.M., April 23, 2002 -- Making antimatter that can't be seen and that otherwise might not exist, filtering it through a nickel's worth of aluminum foil and then capturing it in a "trap" without walls, has the attention of Los Alamos National Laboratory physicist Michael Holzscheiter.

The outcome of work in this field could help shed new light on basic principles of physics and the Big Bang origin-of-the-universe theory. Or it could add new mystery to them.

Big Bang enthusiasts believe the Universe began in an explosion that created equal amounts of mater and antimatter. But if the matter and antimatter were exact mirrors of each other, they would have annihilated, or canceled out, one another. Some theorists say that was avoided because of a slight difference between the two. As a result, matter persisted while antimatter seems to have disappeared as a natural physical phenomenon.

Yet, Holzscheiter notes, antimatter can be a useful research tool. For example, some medical diagnostic procedures, such as Positron Emission Topography (PET) scanning, depend on certain types of antimatter. PET scanning works by attaching radioactive atoms that emit positrons, which are really anti-electrons, to biological tracer molecules. These molecules can be traced as they find their way to specific areas of the body under study.

Aside from positrons, which occur naturally, the only way to get other types of antimatter that could be useful is to make them. Though some types of antimatter have been made, the process has been inefficient and limited.

Holzscheiter reports that his group has made progress in accumulating positrons and antiprotons at low energy as the first step in the process of capturing antihydrogen atoms in large numbers. He belongs to an international collaboration helping feed techniques to the CERN Antimatter Laboratory in Geneva.

A major challenge, even in a controlled laboratory experiment, is to avoid the total annihilation and loss of all the antimatter particles that otherwise would occur when they collide with their normal matter counterparts. Holzscheiter has been able to slow down the burst of energy produced by the collision, enabling him to retain positrons and antiprotons for hours. His research team found that using a small amount of ordinary household aluminum foil gave them a tool that slowed down the high energy burst of antiprotons coming from the accelerator at CERN by a factor of 1,000, enabling them to capture the antimatter in an ultra-high vacuum trap.

Following additional work already underway, the team hopes that perhaps as early as next year they will be able to efficiently "hold on" to the antihydrogen produced from the ingredients in the trap by superimposing a magnetic bottle.

As basic science, antihydrogen research could improve understanding of the interaction of the antihydrogen atom with atoms like hydrogen and oxygen. This could lead to ways of finding whether antimatter galaxies exist somewhere in the universe. Advances in efficient production of antimatter should be useful also to researchers in industry and across different scientific fields.

Los Alamos National Laboratory is operated by the University of California for the National Nuclear Security Administration (NNSA) of the U.S. Department of Energy and works in partnership with NNSA's Sandia and Lawrence Livermore national laboratories to support NNSA in its mission.

Los Alamos enhances global security by ensuring the safety and reliability of the U.S. nuclear weapons stockpile, developing technical solutions to reduce the threat of weapons of mass destruction and solving problems related to energy, environment, infrastructure, health and national security concerns.