@article{ChristHollendungLarueetal.2004,
  author    = {Christ, D. and Hollendung, A. and Larue, H. and Parl, C. and Streun, M. and Weber, S. and Ziemons, Karl and Halling, H.},
  title     = {Homogenization of the MultiChannel PM gain by inserting light attenuating masks},
  series = {2003 IEEE Nuclear Science Symposium Conference Record, Vol. 4},
  journal   = {2003 IEEE Nuclear Science Symposium Conference Record, Vol. 4},
  issn      = {1082-3654},
  pages     = {2382 -- 2385},
  year      = {2004},
  abstract  = {MultiChannel Photomultipliers (PM), like the R7600-00-M64 or R5900-00-M64 from Hamamatsu, are often chosen as photodetectors in high-resolution positron emission tomography (PET). A major problem of this PM is the nonuniform channel gain. In order to solve this problem, light attenuating masks were created. The aim of the masks is a homogenization of the output of all 64 channels using different hole sizes at the channel positions. The hole area, which is individually defined for the different channels, is inversely proportional to the channel gain. The measurements by inserting light attenuating masks improved a homogenization to a ratio of 1:1.2.},
  language  = {en}
}
@article{BeerStreunHombachetal.2010,
  author    = {Beer, S. and Streun, M. and Hombach, T. and Buehler, J. and Jahnke, S. and Khodaverdi, M. and Larue, H. and Minwuyelet, S. and Parl, C. and Roeb, G. and Schurr, U. and Ziemons, Karl},
  title     = {Design and initial performance of PlanTIS: a high-resolution positron emission tomograph for plants},
  series = {Physics in Medicine and Biology},
  volume    = {55},
  journal   = {Physics in Medicine and Biology},
  number    = {3},
  publisher = {IOP},
  address   = {Bristol},
  issn      = {1361-6560},
  doi       = {10.1088/0031-9155/55/3/006},
  pages     = {635 -- 646},
  year      = {2010},
  abstract  = {Positron emitters such as 11C, 13N and 18F and their labelled compounds are widely used in clinical diagnosis and animal studies, but can also be used to study metabolic and physiological functions in plants dynamically and in vivo. A very particular tracer molecule is 11CO2 since it can be applied to a leaf as a gas. We have developed a Plant Tomographic Imaging System (PlanTIS), a high-resolution PET scanner for plant studies. Detectors, front-end electronics and data acquisition architecture of the scanner are based on the ClearPET™ system. The detectors consist of LSO and LuYAP crystals in phoswich configuration which are coupled to position-sensitive photomultiplier tubes. Signals are continuously sampled by free running ADCs, and data are stored in a list mode format. The detectors are arranged in a horizontal plane to allow the plants to be measured in the natural upright position. Two groups of four detector modules stand face-to-face and rotate around the field-of-view. This special system geometry requires dedicated image reconstruction and normalization procedures. We present the initial performance of the detector system and first phantom and plant measurements.},
  language  = {en}
}