Is the flavour experiment at the LHC. It is a forwards spectrometer featuring a precision vertex detector (VELO) with which I have been involved since 1997. The first VELO operated from 2008-2018.
Building on the PSI concept of an r-phi geometry (to enable triggering), and using all the detector technology at Liverpool, I led the design and construction of the original VELO modules. Less well known are two facts:
we built a complete spare velo using n+p technology
VELO modules, and (eventuallz)the original VELO halves, form part of the London Science Museum permanent collection.