london

Scientists at the Stanford Linear Accelerator Center in California started a search on Tuesday (11 May) for evidence of short-lived subatomic particles known as B-mesons, from collisions of electrons and positrons.

The B-mesons and their anti-particles will be detected using a 1,200-tonne particle detector known as BaBar, positioned where the electron and positron beams meet. The experiment is designed to find clues as to why the Universe has more matter than antimatter.

Scientists believe that microseconds after the Big Bang, equal amounts of matter and anti-matter should have annihilated each other. “Mysteriously, a bit of matter was left over,” says Ken Peach of the UK Rutherford Appleton Laboratory, one of the centres involved in the experiment. “By studying particles and their anti-particles we hope to see the tiny differences in behaviour between matter and anti-matter, which will help explain the huge imbalance in the Universe,” adds Peach.

BaBar, which cost $300 million, is the result of collaborative work by more than 500 physicists and engineers from 10 countries.