TY - JOUR A1 - Auffray, E. A1 - Bruyndonckx, P. A1 - Devroede, O. A1 - Fedorov, A. A1 - Ziemons, Karl T1 - The ClearPET project JF - Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment N2 - The Crystal Clear Collaboration has designed and is building a high-resolution small animal PET scanner. The design is based on the use of the Hamamatsu R7600-M64 multi-anode photomultiplier tube and a LSO/LuYAP phoswich matrix with one to one coupling between the crystals and the photo-detector. The complete system will have 80 PM tubes in four rings with an inner diameter of 137 mm and an axial field of view of 110 mm. The PM pulses are digitized by free-running ADCs and digital data processing determines the gamma energy, the phoswich layer and even the pulse arrival time. Single gamma interactions are recorded and coincidences are found by software. The gantry allows rotation of the detector modules around the field of view. Simulations, and measurements a 2×4 module test set-up predict a spatial resolution of 1.5 mm in the centre of the field of view and a sensitivity of 5.9% for a point source in the centre of the field of view. Y1 - 2004 SN - 0168-9002 N1 - Proceedings of the 2nd International Conference on Imaging Technologies in Biomedical Sciences VL - 527 IS - 1-2 SP - 171 EP - 174 ER - TY - JOUR A1 - Streun, M. A1 - Christ, D. A1 - Hellendung, A. A1 - Larue, H. A1 - Ziemons, Karl A1 - Halling, H. T1 - Effects of crosstalk and gain nonuniformity using multichannel PMTs in the Clearpet® scanner JF - Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment N2 - The ClearPET® scanners developed by the Crystal Clear Collaboration use multichannel PMTs as photodetectors with scintillator pixels coupled individually to each channel. In order to localize an event each channel anode is connected to a comparator that triggers when the anode signal exceeds a common predefined threshold. Two major difficulties here are crosstalk of light and the gain nonuniformity of the PMT channels. Crosstalk can generate false triggering in channels adjacent to the actual event. On the one hand this can be suppressed by sufficiently increasing the threshold, but on the other hand a threshold too high can already prevent valid events on the lower gain channels from being detected. Finally, both effects restrict the dynamic range of pulse heights that can be processed. The requirements to the dynamic range are not low as the ClearPET® scanners detect the depth of interaction by phoswich pixels consisting of LSO and Lu0.7Y0.3AP, two scintillators with different light yields. We will present a model to estimate the achievable dynamic range and show solutions to increase it. Y1 - 2005 SN - 0168-9002 N1 - Proceedings of the 7th International Conference on Inorganic Scintillators and their Use in Scientific and Industrial Applications VL - 537 IS - 1-2 SP - 402 EP - 405 ER - TY - JOUR A1 - Ziemons, Karl A1 - Auffray, E. A1 - Barbier, R. A1 - Brandenburg, G. A1 - Bruyndonckx, P. T1 - The ClearPET™ project: Development of a 2nd generation high-performance small animal PET scanner JF - Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment N2 - Second generation high-performance PET scanners, called ClearPET™1, have been developed by working groups of the Crystal Clear Collaboration (CCC). High sensitivity and high spatial resolution for the ClearPET camera is achieved by using a phoswich arrangement combining two different types of lutetium-based scintillator materials: LSO from CTI and LuYAP:Ce from the CCC (ISTC project). In a first ClearPET prototype, phoswich arrangements of 8×8 crystals of 2×2×10 mm3 are coupled to multi-channel photomultiplier tubes (Hamamatsu R7600). A unit of four PMTs arranged in-line represents one of 20 sectors of the ring design. The opening diameter of the ring is 120 mm, the axial detector length is 110 mm.The PMT pulses are digitized by free-running ADCs and digital data processing determines the gamma energy, the phoswich layer and even the exact pulse starting time, which is subsequently used for coincidence detection. The gantry allows rotation of the detector modules around the field of view. Preliminary data shows a correct identification of the crystal layer about (98±1)%. Typically the energy resolution is (23.3±0.5)% for the luyap layer and (15.4±0.4)% for the lso layer. early studies showed the timing resolution of 2 ns FWHM and 4.8 ns FWTM. the intrinsic spatial resolution ranges from 1.37 mm to 1.61 mm full-width of half-maximum (FWHM) with a mean of 1.48 mm FWHM. further improvements in image and energy resolution are expected when the system geometry is fully modeled. Y1 - 2005 SN - 0168-9002 N1 - Proceedings of the 7th International Conference on Inorganic Scintillators and their Use in Scientific and Industrial Applications VL - 537 IS - 1-2 SP - 307 EP - 311 ER - TY - JOUR A1 - Ziemons, Karl T1 - Jet production and fragmentation properties in deep inelastic muon scattering JF - Zeitschrift für Physik C : Particles and Fields Y1 - 1987 SN - 0170-9739 N1 - European Muon Collaboration VL - 36 IS - 4 SP - 527 EP - 543 ER - TY - JOUR A1 - Ziemons, Karl T1 - A measurement of the spin asymmetry of the structure function g1 in deep inelastic muon-proton scattering JF - Physics Letters B N2 - The spin asymmetry in deep inelastic scattering of longitudinally polarised muons by longitudinally polarised protons has been measured over a large x range (0.01