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| Home > Publications database > Commissioning of a cold test system for Outer Tracker Endcap half disks for the Phase-2 upgrade of the CMS experiment |
| Bachelor Thesis | PUBDB-2025-05376 |
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2025
Abstract: The Large Hadron Collider will be upgraded to extend its lifetime and improve various components. With the upgrade to the High-Luminosity-LHC the instantaneous luminosity will increaseto 5 · 1034 cm−2s−1 and the total integrated luminosity to at least 3000 fb−1. To deal with the increased luminosity, the detectors must be upgraded. At the CMS experiment almost the whole detector will be upgraded. This includes the Tracker, which tracks the trajectory of a particle and measures its momentum. To cope with the increased number of events per bunch crossing, the Outer Tracker will be included in the level-1 trigger system. The Outer Tracker consists of a Barrel part and two Endcaps. At the DESY in Hamburg in the CMS Tracker Upgrade group one of the new Outer Tracker Endcaps will be produced. All parts produced for the High-Luminosity-upgrade must be tested before they are installed at the LHC and taken into operation. These tests themselves must also be tested and commissioned.This Bachelor thesis describes how the temperature sensors of a Pixel-Strip-Silicon-sensor-module (PS-module) were calibrated and how a cold test system for Outer Tracker Endcap halfdisks, the so-called Sectortest, is taken into operation. The PS-module, whose sensors were calibrated, is a kick-off module and equipped with additional temperature sensors. This special PS-module is used to gain knowledge about the behaviour of PS-modules and the test setups and is named Galileo.The additional temperature NTC sensors were calibrated first in a temperature chamber. The internal temperature sensors of the PS-module were calibrated by fitting a linear function tothe temperatures of the additional glued sensors. As the linear function has a slope of 0.9, the temperature calibration would be off by approximately 5.5◦C if a constant offset were assumedand this offset was determined at room temperature. In the process of calibrating the PS-module it was observed that the PS-module needs 8 minutes to warm up when the power is turned on, while the Chiller used for cooling it down has an overshoot much smaller than the temperature difference due to the module warming up. The Galileo module cools down simultaneously with its carrier plate when the Burn-In gets cooled down. The Burn-In is a thermal test setup, where individual modules are tested. In the Burn-In tests for the production modules it will not be necessary to wait for the silicon sensor modules to thermalise.The drying and cooling of the Sectortest work well. During the commissioning test it was demonstrated that the Sectortest dries down to the required dew point within a few hours. Theexact time it takes to dry the Sectortest depends on the amount of dry air used. It was also shown that the required dew point was reached with comparatively low dry air flow indicating a good sealing of the box.Inside the Sectortest cooling box a temperature around −20◦C was achieved, which was the target temperature for this setup as this is also the target temperature for the conditions inside the detector. The process of the Sectortest cooling down was studied as well. 6 : 15 h after starting to cool down the Sectortest all sensors in the Sectortest show temperatures that are less than 0.5◦C away from their final temperature. After 13 : 30 h the temperatures are completely stable. When the temperature inside the Sectortest is stabilized, the temperature difference inside remains 7.4◦C. Therefore a fan system should be considered to ensure a more equal temperature distribution.
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