Institute of Radiation Physics y Roland Hannaske y www.fzd.de y Member of the Leibniz Association Nuclear Safety Research Fast Digitizing and Digital Signal Processing of Detector Signals Diploma Thesis of Roland Hannaske, TU Dresden Content: 1. Fast-Digitizer Data Acquisition 2. Pulse-Height Analysis of HPGe Preamplifier Signals 3. Time Resolution of Fast Scintillation Detectors Seminar IKTP, TU Dresden, 20.11.2008
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Institute of Radiation Physics Roland Hannaske www.fzd.de Member of the Leibniz Association
Nuclear Safety Research
Fast Digitizing and Digital Signal Processing of Detector SignalsDiploma Thesis of Roland Hannaske, TU Dresden
Content: 1. Fast-Digitizer Data Acquisition2. Pulse-Height Analysis of HPGe Preamplifier Signals3. Time Resolution of Fast Scintillation Detectors
Seminar IKTP, TU Dresden, 20.11.2008
Institute of Radiation Physics Roland Hannaske www.fzd.de 20.11.2008
Nuclear Safety Research
2
What means digitizing?
Fast Digitizing and Digital Signal Processing of Detector Signals 1. Fast-Digitizer Data Acquisition
digitizing = converting an analog voltage signal to a discrete signal(both in amplitude and time)
Institute of Radiation Physics Roland Hannaske www.fzd.de 20.11.2008
Nuclear Safety Research
3
+ resolution better energy and time resolution compared to analog systems
+ versatility digitized, recorded signals can be analyzed several times with different methods, application of digital methods
Fast-Digitizer Data Acquisition System (FDDAS)
Fast-Digitizer Data Acquisition
Fast Digitizing and Digital Signal Processing of Detector Signals 1. Fast-Digitizer Data Acquisition
PC/serverDSP
(online/offline)
recorder(embedded PC)
fast digitizer(flash ADC)
- trigger preselection of signals (eventually by external trigger)
- hardware requirements transfer at very high data rates, storage and analysis of huge amounts of data
storage area network (SAN)
detector
Institute of Radiation Physics Roland Hannaske www.fzd.de 20.11.2008
Nuclear Safety Research
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HPGe
high-purity Germanium detector (preamplifier signal)• rise time ≈
Institute of Radiation Physics Roland Hannaske www.fzd.de 20.11.2008
Nuclear Safety Research
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nELBE: a neutron time-of-flight
Fast Digitizing and Digital Signal Processing of Detector Signals 3. Time Resolution of Fast Scintillation Detectors
• neutron cross section measurements (relevant for the transmutation of minor actinides in nuclear waste and for application to fission and fusion reactors)→
transmission, inelastic scattering• neutrons from (γ,n) reactions of bremsstrahlung in liquid-lead radiator
experiment at ELBE*
Electron Linac for beams with high Brilliance and low Emittance
Institute of Radiation Physics Roland Hannaske www.fzd.de 20.11.2008
Nuclear Safety Research
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Comparison of timing methods
Fast Digitizing and Digital Signal Processing of Detector Signals 3. Time Resolution of Fast Scintillation Detectors
• LET, ELET → not competitive• ZCT, ZCCFT → improved time resolution with BaF2 detectors• CFT, FCFT → best time resolution with both detector types
Institute of Radiation Physics Roland Hannaske www.fzd.de 20.11.2008
Nuclear Safety Research
15
Summary
Fast Digitizing and Digital Signal Processing of Detector Signals
The fast-digitizer data acquisition system (10 bit, 2 GS/s) of the nELBE experiment was tested successfully with different detector types and a self- developed analysis program.
Using digital timing methods (constant-fraction timing) the time resolution of BaF2 and plastic scintillation detectors improved compared to a state-of-the-art analog signal-processing system.
In pulse-height analysis of HPGe preamplifier signals, the ballistic deficit was corrected with the moving window deconvolution algorithm. The energy resolution of analog signal processing using a 14-bit ADC was not reached.
Publication: R. Hannaske, Wissenschaftlich-Technische Berichte, Forschungszentrum Dresden-Rossendorf, FZD-510, 2009
Institute of Radiation Physics Roland Hannaske www.fzd.de 20.11.2008
Nuclear Safety Research
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Acknowledgement
Prof. R. Sauerbreysupervising professor and first reviewer
Prof. T. Cowansecond reviewer
Dr. A. Wagnersupervisor
Dr. A. Junghansproject leader nELBE
R. Beyer, Dr. P. Crespo, A. Dammrau, M. Fauth, Prof. E. Grosse, Dr. A. Matic, Dr. R. Schwengner
Nuclear Physics Division, Institute of Radiation Physics
Fast Digitizing and Digital Signal Processing of Detector Signals