Speaker
Description
The LHCb experiment has been upgraded during the second long shutdown
of the Large Hadron Collider at CERN, and the new detector is currently
operating at the LHC. The Vertex Locator (VELO) is the detector
surrounding the interaction region of the LHCb experiment, responsible of
reconstructing the proton-proton collision (primary vertices) as well as
the decay vertices of long-lived particles (secondary vertices).
The VELO is composed by 52 modules with hybrid pixel detector technology,
operating at just 5.1 mm from the beams. The sensors consist of
200 $\mu$m thick n-on-p planar silicon sensors, read out via 3 VeloPix ASICs.
The sensors are attached to a 500 $\mu$m thick silicon plate, which embeds
19 micro-channels for the circulation of the CO$_2$ evaporative cooling.
The VELO operates in an extreme environment, which poses significant challenges
to its operation. During the lifetime of the detector, the sensors are foreseen
to accumulate an integrated fluence of up to $8\times10^{15}$ 1MeV n$_{\rm eq}$cm$^{-2}$,
roughly equivalent to a dose of 400 MRad. Moreover, due to the geometry
of the detector, the sensors will face a highly non-uniform irradiation,
with fluences in the hottest regions expected to vary by a factor 400 within the same sensor.
The highest occupancy ASICs foresee a maximum pixel hit rate of 900 Mhit/s and an output
data rate exceeding 15 Gbit/s. The design, operation and early results obtained during
the first year of commissioning will be presented.
