@article{StreunBrandenburgBroekeletal.2004,
  author    = {Streun, M. and Brandenburg, G. and Br{\"o}kel, M. and Fuss, L. and Larue, H. and Parl, C. and Zimmermann, E. and Ziemons, Karl and Halling, H.},
  title     = {The ClearPET data acquisition},
  series = {2003 IEEE Nuclear Science Symposium Conference Record, Vol. 5},
  journal   = {2003 IEEE Nuclear Science Symposium Conference Record, Vol. 5},
  issn      = {1082-3654},
  pages     = {3097 -- 3100},
  year      = {2004},
  abstract  = {Within the Crystal Clear Collaboration a modular system for a small animal PET scanner (ClearPET™) has been developed. The modularity allows the assembly of scanners of different sizes and characteristics in order to fit the specific needs of the individual member institutions. Now a first demonstrator is being completed in Julich. The system performs depth of interaction detection by using a phoswich arrangement combining LSO and LuYAP scintillators which are coupled to multi-channel photomultipliers (PMTs). A free-running ADC digitizes the signal from the PMT and the complete scintillation pulses are sampled by an FPGA and sent with 20 MB/S to a PC for preprocessing. The pulse provides information about the gamma energy and the scintillator material which identifies the interaction layer. Furthermore, the exact pulse starting time is obtained from the sampled data. This is important as no hardware coincidence detection is implemented. All single events are recorded and coincidences are identified by software. An advantage of that is that the coincidence window and the dimensions of the field of view can be adjusted easily. The ClearPET™ demonstrator is equipped with 10240 crystals on 80 PMTs. This paper presents an overview of the data acquisition system.},
  language  = {en}
}
@article{StreunBrandenburgLarueetal.2003,
  author    = {Streun, M. and Brandenburg, G. and Larue, H. and Saleh, H. and Zimmermann, E. and Ziemons, Karl and Halling, H.},
  title     = {Pulse shape discrimination of LSO and LuYAP scintillators for depth of interaction detection in PET},
  series = {2002 IEEE Nuclear Science Symposium Conference Record, Vol. 3},
  journal   = {2002 IEEE Nuclear Science Symposium Conference Record, Vol. 3},
  issn      = {1082-3654},
  pages     = {1636 -- 1639},
  year      = {2003},
  abstract  = {A feasible way to gain the depth of interaction information in a PET scanner is the use of phoswich detectors. In general the layer of interaction is identified front the pulse shape of the corresponding scintillator material. In this work pulses from LSO and LuYAP crystals were investigated in order to find a practical method of distinguishing. It turned out that such a pulse processing could he kept simple due to an additional slow component in the light decay of the LuYAP pulse. At the same time the short decay time guarantees that the major amount of the light output is still collected within a short pulse recording time.},
  language  = {en}
}
@article{StreunBrandenburgLarueetal.2003,
  author    = {Streun, M. and Brandenburg, G. and Larue, H. and Saleh, H. and Zimmermann, E. and Ziemons, Karl and Halling, H.},
  title     = {Pulse shape discrimination of LSO and LuYAP scintillators for depth of interaction detection in PET},
  series = {IEEE Transactions on Nuclear Science},
  volume    = {50},
  journal   = {IEEE Transactions on Nuclear Science},
  number    = {3},
  isbn      = {0018-9499},
  pages     = {344 -- 347},
  year      = {2003},
  abstract  = {A feasible way to gain the depth of interaction information in a positron emission tomography scanner is the use of phoswich detectors. In general, the layer of interaction is identified from the pulse shape of the corresponding scintillator material. In this work, pulses from LSO and LuYAP crystals were investigated in order to find a practical method of distinguishing. It turned out that such a pulse processing could be kept simple because of an additional slow component in the light decay of the LuYAP pulse. At the same time, the short decay time guarantees that the major amount of the light output is still collected within a short pulse recording time.},
  language  = {en}
}
@article{StreunBrandenburgLarueetal.2002,
  author    = {Streun, M. and Brandenburg, G. and Larue, H. and Zimmermann, E. and Ziemons, Karl and Halling, H.},
  title     = {A PET system with free running ADCs},
  series = {Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment},
  volume    = {486},
  journal   = {Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment},
  number    = {1-2},
  issn      = {0168-9002},
  pages     = {18 -- 21},
  year      = {2002},
  abstract  = {A small PET system has been built up with two multichannel photomultipliers, which are attached to a matrix of 64 single LSO crystals each. The signal from each multiplier is being sampled continuously by a 12 bit ADC at a sampling frequency of 40 MHz. In case of a scintillation pulse a subsequent FPGA sends the corresponding set of samples together with the channel information and a time mark to the host computer. The data transfer is performed with a rate of 20 MB/s. On the host all necessary information is extracted from the data. The pulse energy is determined, coincident events are detected and multiple hits within one matrix can be identified. In order to achieve a narrow time window the pulse starting time is refined further than the resolution of the time mark (=25 ns) would allow. This is possible by interpolating between the pulse samples. First data obtained from this system will be presented. The system is part of developments for a much larger system and has been created to study the feasibility and performance of the technique and the hardware architecture.},
  language  = {en}
}
@article{StreunBrandenburgLarueetal.2002,
  author    = {Streun, M. and Brandenburg, G. and Larue, H. and Zimmermann, E. and Ziemons, Karl and Halling, H.},
  title     = {Coincidence detection by digital processing of free-running sampled pulses},
  series = {Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment},
  volume    = {487},
  journal   = {Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment},
  number    = {3},
  isbn      = {0168-9002},
  pages     = {530 -- 534},
  year      = {2002},
  abstract  = {Coincident events in two scintillator crystals coupled to photomultipliers (PMT) are detected by processing just the digital data of the recorded pulses. For this purpose the signals from both PMTs are continuously sampled by free-running ADCs at a sampling rate of 40 MHz. For each sampled pulse the starting time is determined by processing the pulse data. Even a fairly simple interpolating algorithm results in a FWHM of about 2 ns.},
  language  = {en}
}
@article{StreunBrandenburgLarueetal.2002,
  author    = {Streun, M. and Brandenburg, G. and Larue, H. and Zimmermann, E. and Ziemons, Karl and Halling, H.},
  title     = {A PET system based on data processing of free-running sampled pulses},
  series = {2001 IEEE Nuclear Science Symposium Conference Record, Vol. 2},
  journal   = {2001 IEEE Nuclear Science Symposium Conference Record, Vol. 2},
  issn      = {1082-3654},
  pages     = {693 -- 694},
  year      = {2002},
  abstract  = {Within the developments for the Crystal Clear small animal PET project (CLEARPET) a dual head PET system has been established. The basic principle is the early digitization of the detector pulses by free running ADCs. The determination of the γ-energy and also the coincidence detection is performed by data processing of the sampled pulses on the host computer. Therefore a time mark is attached to each pulse identifying the current cycle of the 40 MHz sampling clock. In order to refine the time resolution the pulse starting time is interpolated from the samples of the pulse rise. The detector heads consist of multichannel PMTs with a single LSO scintillator crystal coupled to each channel. For each PMT only one ADC is required. The position of an event is obtained separately from trigger signals generated for each single channel. An FPGA is utilized for pulse buffering, generation of the time mark and for the data transfer to the host via a fast I/O-interface.},
  language  = {en}
}
@article{StreunBrandenburgLarueetal.2001,
  author    = {Streun, M. and Brandenburg, G. and Larue, H. and Zimmermann, E. and Ziemons, Karl and Halling, H.},
  title     = {Pulse recording by free-running sampling},
  series = {IEEE Transactions on Nuclear Science},
  volume    = {48},
  journal   = {IEEE Transactions on Nuclear Science},
  number    = {3},
  isbn      = {0018-9499},
  pages     = {524 -- 526},
  year      = {2001},
  abstract  = {Pulses from a position-sensitive photomultiplier (PS-PMT) are recorded by free-running ADCs at a sampling rate of 40 MHz. A four-channel acquisition board has been developed which is equipped with four 12-bit ADCs connected to one field programmable gate array (FPGA). The FPGA manages data acquisition and the transfer to the host computer. It can also work as a digital trigger, so a separate hardware trigger can be omitted. The method of free-running sampling provides a maximum of information, besides the pulse charge and amplitude also pulse shape and starting time are contained in the sampled data. This information is crucial for many tasks such as distinguishing between different scintillator materials, determination of radiation type, pile-up recovery, coincidence detection or time-of-flight applications. The absence of an analog integrator allows very high count rates to be dealt with. Since this method is to be employed in positron emission tomography (PET), the position of an event is also important. The simultaneous readout of four channels allows localization by means of center-of-gravity weighting. First results from a test setup with LSO scintillators coupled to the PS-PMT are presented here},
  language  = {en}
}
@article{StreunBrandenburgLarueetal.2000,
  author    = {Streun, M. and Brandenburg, G. and Larue, H. and Zimmermann, E. and Ziemons, Karl and Halling, H.},
  title     = {Pulse recording by free-running sampling},
  series = {2000 IEEE Nuclear Science Symposium Conference Record, Vol. 2},
  journal   = {2000 IEEE Nuclear Science Symposium Conference Record, Vol. 2},
  issn      = {1082-3654},
  pages     = {9/179 -- 9/181},
  year      = {2000},
  abstract  = {Pulses from a position-sensitive photomultiplier (PS-PMT) are recorded by free running ADCs at a sampling rate of 40 MHz. A four-channel acquisition-board has been developed which is equipped with four 12 bit-ADCs connected to one FPGA (field programmable gate array). The FPGA manages data acquisition and the transfer to the host computer. It can also work as a digital trigger, so a separate hardware-trigger can be omitted. The method of free running sampling provides a maximum of information, besides the pulse charge and amplitude also pulse shape and starting time are contained in the sampled data. These informations are crucial for many tasks such as distinguishing between different scintillator materials, determination of radiation type, pile-up recovery, coincidence detection or time-of-flight applications. The absence of an analog integrator allows coping with very high count rates. Since this method is going to be employed in positron emission tomography (PET), the position of an event is another important information. The simultaneous readout of four channels allows localization by means of center-of-gravity weighting. First results from a test setup with LSO-scintillators coupled to the PS-PMT are presented},
  language  = {en}
}