@article{HeinrichsPietrzykZiemons2003,
  author    = {Heinrichs, U. and Pietrzyk, Uwe and Ziemons, Karl},
  title     = {Design optimization of the PMT-ClearPET prototypes based on simulation studies with GEANT3},
  series = {2002 IEEE Nuclear Science Symposium Conference Record, Vol. 3},
  journal   = {2002 IEEE Nuclear Science Symposium Conference Record, Vol. 3},
  issn      = {1082-3654},
  pages     = {682 -- 686},
  year      = {2003},
  abstract  = {Within the Crystal Clear Collaboration four centres are developing 2nd generation high performance small animal PET scanners for different kinds of animals and medical applications. The first prototypes are PMT-based systems including depth of interaction (DOI) detection by using a phoswich layer of LSO and LuYAP. The aim of these simulation studies is to optimize sensitivity and spatial resolution of given designs, which vary in FOVs caused by different detector configurations (ring/octagon) and sizes. For this purpose the simulation tool GEANT3 (CERN) was used. The simulations have shown that all PMT designs with one-to-one coupling of crystals have a very nonlinear axial sensitivity profile. By shifting every other PMT 1/4 of a PMT length in axial direction the sampling of the FOVs became more homogeneous. At an energy threshold of 350keV the regression coefficient increases from 0.818 for the non-shifted to 0.993 for the shifted design. Simulations of a point source centred in the FOV (threshold: 350keV) resulted in sensitivities of 4.2\% for a 4×20PMT (LSO/LuYAP a 10mm) and 3.8\% for a 4×16PMT (LSO/LuYAP a 8mm) ring design. The 3D-MLEM reconstruction of a point source shows the enormous improvement of resolution using a crystal double layer with DOI (3.1mm at 40mm from CFOV) instead of a 20mm single layer (11.9mm).},
  language  = {en}
}
@article{LustfeldPithanReissel2012,
  author    = {Lustfeld, Hans and Pithan, C. and Reißel, Martin},
  title     = {Metallic electrolyte composites in the framework of the brick-layer model},
  series = {Journal of the European Ceramic Society},
  volume    = {32},
  journal   = {Journal of the European Ceramic Society},
  number    = {4},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0955-2219},
  doi       = {10.1016/j.jeurceramsoc.2011.10.017},
  pages     = {859 -- 864},
  year      = {2012},
  abstract  = {It is well known that the already large dielectric constants of some electrolytes like BaTiO₃ can be enhanced further by adding metallic (e.g. Ni, Cu or Ag) nanoparticles. The enhancement can be quite large, a factor of more than 1000 is possible. The consequences for the properties will be discussed in the present paper applying a brick-layer model (BLM) for calculating dc-resistivities of thin layers and a modified one (PBLM) that includes percolation for calculating dielectric properties of these materials. The PBLM results in an at least qualitative description and understanding of the physical phenomena: This model gives an explanation for the steep increase of the dielectric constant below the percolation threshold and why this increase is connected to a dramatic decrease of the breakdown voltage as well as the ability of storing electrical energy. We conclude that metallic electrolyte composites like BaTiO₃ are not appropriate for energy storage.},
  language  = {en}
}