Digital Pulse Processor for processing signal from radiation detectors.pptx

Mowing window deconvolution. digital filters

1. Digital Pulse Processor Moving Window Deconvolution (MWD)

2.   PPC – Pra-ampfifier Peka Cas (Charge Sensitive Preamp.) A = Amplitude,  = Time constant MCA

3. Digital Pulse Shaper => Trapezoidal Shaper Why? : Superior noise figure (High resolution), reduces ballistic deficit & excellent baseline stabilitiy @ high count-rate. Algorithm: Moving-Window Deconvolution (MWD) – Georgiev & Gast 1992, Jordanov & Knoll (1993), Martin Lauer (2004) Initial Pulse amplitude can be obtained at Amplitude at any point within the signal by knowing the decay time & starting point of the signal Analogue domain   = Amplitude at time, ,     = sampling time  

4. Digital Pulse Shaper => Trapezoidal Shaper   = sampling time   Differentiation of (2) with moving window with width M yield MWD equation: = With Deconvolution & Moving window Eq.(3) deduced to:- MWD does not filter the noise? Need low-pass filter i.e., Moving Average with sampling L ( ). Pulse , if L = M -> Triangular Shaper, L  M  Trapezoid Shaper (Flat top width = M-L)  

5. Digital Pulse Shaper => Trapezoidal Shaper: Principle of operation Preamp Pulse (Digitised pulse) After Deconvolution, ( )   After Moving-Window, ( )   After Moving Average Filter,    

6. Useful readings: Jordanov, V., dan G. F. Knoll. 1993 . Digital pulse processor using moving average technique. Nuclear Science, IEEE Transactions on 40 (4):764-769 Georgiev, A., dan W. Gast. 1992 . Digital pulse processing in high-resolution, high-throughput, gamma-ray spectroscopy . Nuclear Science Symposium and Medical Imaging Conference, 1992., Conference Record of the 1992 IEEE, 25-31 Oct 1992. Lauer, Martin. 2004. PhD Thesis, Digital Signal Processing for segmented HPGe Detectors: Preprocessing Algorithms and Pulse Shape Analysis , Max-Planck-Insitut für Kernphysik, University of Heidelberg, Heidelberg.