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@INPROCEEDINGS{Guthoff:598020,
      author       = {Guthoff, Moritz and Agah, Abbas and Zuber, Adam and Velyka,
                      Anastasiia and Mussgiller, Andreas and Muhl, Carsten and
                      Pacifico, Nicola and Reichelt, Oskar and Wang, Qun and
                      Stever, Reimer and Waldych, Sarah},
      title        = {{R}adiation qualification of thermal interface materials
                      for detector cooling},
      reportid     = {PUBDB-2023-06707},
      year         = {2023},
      abstract     = {Silicon sensor based particle detectors operated in an
                      hadronic radiation environment need to be cooled to
                      counteract the radiation induced leakage current and prevent
                      thermal runaway. To achieve this most efficiently, a low
                      thermal resistance is required between the detector modules
                      and the cooling structures. In many cases dry thermal
                      contacts are sufficient, but especially for large area
                      contact so-called thermal interface materials (TIM) - of
                      which many products are available on the market - are the
                      preferred choice. However, in the use case for detector
                      cooling there are many requirements, such as no liquid, no
                      heat cure, low thermal impedance, no compression force,
                      radiation hardness, making it more difficult to find a
                      suitable TIM. An example use case is the cooling of the CMS
                      Phase-2 Outer Tracker PS modules. Its entire underside of 5
                      x 13 cm must be thermally coupled to the mechanics. The
                      current candidate materials are room temperature curing two
                      component thermal gap fillers.The contribution will outline
                      the measurements and highlight the results to qualify gap
                      filler materials to the radiation dose expected for the
                      lifetime of the CMS Outer Tracker. Three different types
                      have been tested thermally and mechanically in this
                      campaign.The thermal test setup determines the thermal
                      conductivity of a test sample by measuring the temperature
                      gradient with a controlled amount of heat flow through a
                      sample. The development and calibration of this custom
                      thermal conductivity measurement setup is detailed in a
                      separate contribution to this conference.Mechanical tests
                      are needed to ensure structural integrity of the thermal
                      interface even when under some extent of thermal stress.
                      Since the gap fillers can not be considered glues in
                      classical sense, the standard lap shear and peel tests can't
                      be used for qualification. Resembling the style of an ISO
                      4587 lap shear test, and an ISO 25217 mode-1 fracture test,
                      test samples were made with a large 5 x 5 cm adhesion
                      overlap using plasma cleaned carbon fibre plates to have a
                      surface comparable to its intended use case. The testing
                      method developed for this study will be presented and
                      motivated.After testing of unirradiated samples, they have
                      been irradiated to 600 kGy. The measured mechanical and
                      thermal properties will be presented and the results before
                      and after irradiation will be compared. We found that the
                      gap filler material hardens significantly, however its
                      thermal and adhesive properties are maintained. The
                      hardening reduces the cohesion failure, leading to an
                      increased mechanical strength.},
      month         = {Aug},
      date          = {2023-08-21},
      organization  = {European Physical Society Conference
                       on High Energy Physics 2023, Hamburg
                       (Germany), 21 Aug 2023 - 25 Aug 2023},
      cin          = {CMS},
      cid          = {I:(DE-H253)CMS-20120731},
      pnm          = {611 - Fundamental Particles and Forces (POF4-611)},
      pid          = {G:(DE-HGF)POF4-611},
      experiment   = {EXP:(DE-MLZ)NOSPEC-20140101},
      typ          = {PUB:(DE-HGF)24},
      url          = {https://bib-pubdb1.desy.de/record/598020},
}