  The thermal properties of the LHCb Vertex Locator (VELO) are studied using
the real-time detector alignment procedure. The variation of the position and
orientation of the detector elements as a function of the operating temperature
of the VELO is presented. This study uses a dataset collected by the LHCb
experiment during a VELO temperature scan performed at the end of LHC Run 2
(October 2018). Significant shrinkage of the VELO modules is observed at the
operating temperature of $-30^\circ$ compared to the laboratory measurements on
a single module taken at a range of temperatures from $+45^\circ$ to
$-25^\circ$. The thermal shrinkage expected from the extrapolation of
laboratory measurements to lower temperatures, and the results of this
alignment study are in good agreement.
