Mass-Producing Positrons

摘要

How do black holes form? Where do gamma-ray bursts originate in space? Why does matter dominate over antimatter in the universe? No one really knows. However, through the study of positrons, the antiparticles of electrons, scientists believe they may gain insight into these complex astrophysical questions.rnPositrons are elementary particles whose physical properties, such as spin and mass, are the same as electrons, except that positrons have a positive charge. For years, scientists have theorized that lasers could be used to generate positrons in a laboratory by "zapping" an ultrathin micrometer-size foil target made of a high-atomic-number (high-Z) material, such as gold or tantalum. Researchers at Livermore recently showed that targets thicker than a few micrometers are a more efficient mechanism for positron generation.