LHCb - The VELO Looks for Vertices but Who Looks after the VELO?

The Vertex Locator (VELO) is the innermost part of the LHCb detector, positioned around 3.5mm from the collision region, inside the LHC vacuum. For safety, both halves are held away from the beams during injection. Then, each half reconstructs the position of the primary vertices, allowing the VELO to close and centre around the colliding beams. The VELO closes in several stages, with safety criteria being automatically checked at each stage. The VELO was closed for the first time in Run 3 in October. Using initial data taken from the first closing, we can study the shape of the RF foil from hadronic interactions with the material. This can be compared to the design position, and can also be used to verify that the VELO is well centred around the beams