Speaker
Description
Authors: Mighty Tracker Collaboration
Corresponding authors: joanna.liberadzka-porret@epfl.ch, gauri.napoletano@epfl.ch
Abstract:
In view of LHCb Upgrade II, taking place during Long Shutdown 4, the detector is going to be modified to operate at a several times higher instantaneous luminosity compared to Upgrade I. The Mighty-Tracker, which replaces the present Scintillating Fibre (SciFi) Tracker, will be composed of an inner pixel detector, called Mighty-Pixel, and an outer one consisting of scintillating fibres, known as Mighty-SciFi. A major challenge for the Mighty-SciFi is the operation of the Silicon PhotoMultipliers (SiPMs) in the radiation environment. To mitigate the increased level of radiation due to higher luminosity in Run 5, the photo-detectors are cooled to approximately 100 K to guarantee low noise (dark-count rate).
Dedicated vacuum insulated coldboxes have been designed, that integrate into the support C-Frame and SciFi mat modules. They house the 2K SiPM readout channels that allow for a spatial hit resolution of 100 µm. The coldbox design is optimised to provide low thermal contact between the SiPMs and SciFi mats on one side and the readout electronics outside the vacuum boxes on the other. With the help of the vacuum insulation and the thermal design optimisation, a total of less than 10 W of cooling power is required for a full box.
Two full-scale demonstrator setups cooled with liquid nitrogen have been built and operated confirming the thermal simulations. The operation of the Mighty-SciFi demonstrators allowed to confirm the expected detector response using signal injection with an electron source. Details of the mechanical design along with the cooling strategy, obtained temperatures and photo-detector response are presented.