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@PHDTHESIS{Mehta:361551,
      author       = {Mehta, Shaifali},
      othercontributors = {Schmidt, Hans-Rudolf},
      title        = {{I}nvestigation of thermal and structural integrity of
                      modules and ladders of {S}ilicon {T}racking {S}ystem of the
                      {CBM} experiment},
      school       = {Eberhard Karls Universität Tübingen},
      type         = {Dissertation},
      address      = {Tübingen},
      publisher    = {Universität Tübingen},
      reportid     = {GSI-2025-00978},
      pages        = {171 p.},
      year         = {2025},
      note         = {Dissertation, Eberhard Karls Universität Tübingen, 2024},
      abstract     = {The Compressed Baryonic Matter (CBM) at the Facility for
                      Antiproton and Ion Research (FAIR) is a fixed target
                      experiment designed to investigate the properties of
                      strongly interacting matter in the region of high net-baryon
                      density. The Silicon Tracking System (STS) is the core
                      detector of the CBM experiment and aims to track and measure
                      the momentum of the charged particles. The STS detector
                      comprises of 876 double sided silicon micro-strip sensors
                      connected via micro cables to the Front-End Boards (FEBs)
                      which are kept outside the detector acceptance of 2.5° to
                      25°. These sensors are mounted on 106 carbon fiber ladders
                      which includes standard ladders and central ladders with an
                      opening for the beam-pipe. For good particle tracking
                      accuracy in the CBM, the silicon sensors must be mounted on
                      the ladders with extremely high precision, minimizing
                      misalignment and optimizing the spatial resolution of the
                      detector. The experimental operating conditions of STS
                      present challenges to the electronics due to a highly
                      variable thermal environment. A significant portion of the
                      thesis focuses on the thermal studies of the STS components.
                      This involves a detailed investigation of the requirements
                      for thermal interface materials (TIMs) between the FEBs and
                      the cooling shelves. The study includes optimization
                      techniques for adhesive application and thermal testing to
                      ensure the effectiveness of the TIMs. To ensure the reliable
                      functioning of FEBs under significant temperature
                      variations, thermal cycling tests were conducted, and
                      potential failure scenarios have been analyzed. The main
                      focus of the thesis is the understanding of the structural
                      integrity of the STS detector. It is investigated how the
                      STS ladders, essential for supporting the silicon sensors,
                      are put together and how they perform. The design and
                      quality assurance processes for carbon fiber ladders are
                      examined, followed by a step-by-step description of the
                      ladder assembly procedure. The evolution of the ladder
                      assembly procedures, from initial prototypes to fully
                      functional ladders with the required mounting precision are
                      highlighted. The developed procedure is designed to be
                      iterative and easily adaptable for producing 106 STS
                      ladders. The final section of the thesis addresses the
                      vibration challenges encountered by the STS ladders due to
                      air cooling, which is essential for maintaining the sensor
                      performance. It describes the experimental setups used to
                      measure the eigenfrequencies and vibrations on the sensor
                      surface under airflow conditions. The study uses a
                      perforated tube to direct airflow onto the sensor surfaces
                      and highlights the performance differences between the
                      standard and central ladders. Through the analysis of
                      vibration magnitude, the impact of airflow on the stability
                      of the silicon sensors once they are mounted on the ladders,
                      is evaluated. These findings underline the significance of
                      effective vibration control to maintain sensor stability.
                      This thesis provides a comprehensive understanding of both
                      thermal management and structural integrity of the STS.
                      Through extensive testing of TIM and thermal cycling of the
                      FEBs, the last step of the module assembly process has been
                      optimized, resulting in a reliable TIM now used in the
                      series production of the modules. Along this work,
                      significant progress has been made in developing the ladder
                      assembly procedure, which is now being implemented for all
                      the ladders, with series production already underway. The
                      central ladder assembly procedure has been optimized and
                      validated with a prototype ladder. The vibration
                      measurements have established the boundary conditions for
                      airflow through the perforated tube, ensuring the mechanical
                      integrity and necessary cooling to prevent thermal runaway.},
      keywords     = {530 (Other)},
      cin          = {CBM@FAIR},
      cid          = {I:(DE-Ds200)Coll-FAIR-CBM},
      pnm          = {612 - Cosmic Matter in the Laboratory (POF4-612)},
      pid          = {G:(DE-HGF)POF4-612},
      experiment   = {EXP:(DE-Ds200)FAIR-Facility},
      typ          = {PUB:(DE-HGF)11},
      urn          = {urn:nbn:de:bsz:21-dspace-1633592},
      doi          = {10.15496/PUBLIKATION-104689},
      url          = {https://repository.gsi.de/record/361551},
}