In autumn 2013 an exhibition about the LHC will open in the Science Museum, and we’re currently scouting out objects and stories for the show. This post is the first in a series about the exhibition. Myself and Harry Cliff from the LHC exhibition team ventured to Liverpool to take a closer look at the detector that sits at the heart of the LHCb experiment.
The Oliver Lodge building, home to the Universityof Liverpool particle physics department, is a typically plain post-war block. But inside, technicians and researchers constructed one of the most beautiful parts of the Large Hadron Collider (LHC): the LHCb Vertex Locator or “VELO”.
The VELO is a precision engineered piece of equipment, and we had to put on teletubby-style outfits to enter the clean room where the modules were painstakingly put together. A peek through a microscope at a spare module revealed the intricate detail in each board; hundreds of perfectly aligned connections, delicate strips of silicon and tiny computer chips.
But once assembled, the modules are surprisingly hardy. Some were taken to the LHC in Geneva in hand baggage on an easyJet flight; brave researchers drove the rest through the Channel tunnel in a hire car. Once they arrived, this incredibly intricate device was carefully put in position. It sits just millimetres from awesome power of the LHC’s proton beams, enduring high levels of radiation for years on end without missing a beat.
Most of media flurry about the LHC has concentrated on the hunt for the Higgs boson. LHCb has a different mission. As Dr Tara Shears explained, our universe is made of normal matter, not its mirror image, antimatter, and at LHCb scientists are attempting to find out where the antimatter has gone.
The LHC collides protons at near light speed. The energy of the crash creates new particles that spray out in all directions. Our host at Liverpool, Dr Girish Patel, explained that the VELO comprises 42 modules, which are lined up in pairs to form circular detectors – the proton beams travel through the hole in the centre of each pair. The pairs are lined up along the beam to record the trajectory of the new particles.
The VELO allows scientists to work out precisely where particles were created, to within a hundredth of a millimetre. It is surrounded by much larger detectors that identify what types of particle were made in each collision. LHCb is looking for a type of particle known as a bottom quark. It doesn’t detect the bottom particles directly, because they decay into other particles before they reach VELO. LHCb tracks these other particles, looking for the fingerprint of the bottom quark among the mass of data.
Thanks to everyone at Liverpool for a fascinating day, particularly Girish, Tara and Themis. For more info on the VELO, take a look at the LHCb website.
Image courtesy of CERN