The Large Hadron Collider at CERN
The LHCb collaboration at CERN has made its first observations of matter – antimatter asymmetry in the decays of the particle known as the B0s.
Matter and antimatter are thought to have existed in equal amounts at the beginning of the universe, but today the universe appears to be composed essentially of matter.
Subtle differences
By studying subtle differences in the behaviour of particle and antiparticles, experiments at the LHC are seeking to cast light on this dominance of matter over antimatter.
The LHCb experiment has observed a preference for matter over antimatter known as CP-violation in the decay of neutral B0s particles – only the fourth subatomic particle known to exhibit such behaviour.
The VELO sub-detector is key to selecting Bs mesons from all other particles produced inside LHCb. It has 42 modules containing half-moon-shaped silicon detectors, which were designed, assembled and tested at the University.
The detectors can locate particles to within a hundredth of a millimeter, within millionths of a second. It is this precision that allows physicists to reconstruct the very short flight distance characteristic of a Bs meson, on a timescale that allows this signature to be recognised in real time, so that the data is recorded to make the measurement.
One step further
Professor Tara Shears, part of the LHCb team at the University’s Department of Physics, said: “This new discovery reveals another layer in our search to understand what makes antimatter that little bit different to normal matter.
“It shows us that our understanding of how matter and antimatter behave is remarkably consistent – but also that the differences we’ve seen between them are too small to explain why we live in a universe dominated by matter.
“Understanding the nature of antimatter is still very much an open and important question, and today’s discovery takes us one step further towards our goal.”
