Physicists Successfully Trap a Single Antimatter Particle for Months

Isolating a Solitary Positron

Physicists have successfully captured and contained a single subatomic particle of antimatter for months at a time. Studying antimatter is notoriously difficult because it typically annihilates instantly upon coming into contact with normal matter.

Led by Northwestern University physicist Gerald Gabrielse, a research team achieved this isolation to better examine the quantum states of the material. Their findings were recently reported in Physical Review Letters.

The Trapping Process

To acquire the antimatter, the researchers started with sodium 22, a radioactive isotope possessing a half-life of approximately two and a half years. When these atoms decay, they release positrons, which serve as the antimatter counterparts to ordinary electrons.

The primary challenge involved slowing down and capturing these fast-moving particles. By guiding the positrons through the crystal lattice of a cold tungsten sliver, the team forced the particles to lose energy. Surviving particles were then channeled via electromagnetic fields into a vacuum container positioned just fractions of a degree above absolute zero.

Within this vacuum, electric fields on the top and bottom combined with magnetic fields on the sides to hold the solitary particle inside a container devoid of physical walls.

Future Research Goals

By isolating a single positron for an extended period, scientists hope to perform precise measurements of its magnetic moment. Researchers intend to determine the energy required to flip the direction of the positron's spin as well as the energy needed to drive a jump from its ground state to its first excited state.

Comparing these measurements against equivalent data gathered from standard electrons will allow researchers to test predictions outlined by the Standard Model of particle physics. If a discrepancy emerges, it could offer vital clues regarding why the observable universe consists primarily of matter rather than antimatter.

Sources: Scientific American, American Physical Society, Phys.org.