The LHCb VELO Upgrade detector: design, construction and installation

<!--HTML--><p class="MsoPlainText">During the Long Shutdown 2 of the LHC, LHCb installed a new VErtex LOcator (VELO), which replaced the one operated during Run 1 and Run 2 of the LHC. The upgraded detector consists of 52 hybrid silicon pixel modules, placed along the beam axis and divided into 2 retractable halves. The detector operates in a secondary vacuum, separated from the beam vacuum by a 150<span style="font-family:Symbol;mso-ascii-font-family:Calibri;mso-char-type:symbol;mso-hansi-font-family:Calibri;mso-symbol-font-family:Symbol;">m</span>m custom-made Aluminium foil. Each VELO modules is equipped with 4 p-on-n silicon pixel sensors, read out by 3 VeloPix ASICs with 55<span style="font-family:Symbol;mso-ascii-font-family:Calibri;mso-char-type:symbol;mso-hansi-font-family:Calibri;mso-symbol-font-family:Symbol;">m</span><span style="font-family:&quot;Calibri&quot;,sans-serif;font-size:11.0pt;mso-ansi-language:EN-GB;mso-ascii-theme-font:minor-latin;mso-bidi-font-family:&quot;Times New Roman&quot;;mso-bidi-language:AR-SA;mso-bidi-theme-font:minor-bidi;mso-fareast-font-family:Calibri;mso-fareast-language:EN-US;mso-fareast-theme-font:minor-latin;mso-hansi-theme-font:minor-latin;">m²&nbsp;</span> pixels. The new detector has also been moved closer to the beam line by a factor of 1.6, with the innermost active region now at only 5.1mm from the beams. The module assembly has started in July 2020 and completed in December 2021. The detector was then installed in the LHCb cavern during the first half of 2022 and it is currently being commissioned. The assembly of the VELO modules required high precision in many aspects. Extensive procedures for its quality assurance have been deployed. In this seminar, the challenges faced during production will be discussed, as well as the work carried out during the installation and integration in the LHCb cavern.</p>