Changeset 6273

Timestamp:

02/04/05 21:03:11 (20 years ago)

Author:

gaug

Message:

*** empty log message ***

File:

• trunk/MagicSoft/TDAS-Extractor/Algorithms.tex (modified) (3 diffs)

trunk/MagicSoft/TDAS-Extractor/Algorithms.tex

@@ -197 +197 @@
 As it does not correct for the clock-noise, only an even number of samples is allowed.
 For a high intensity calibration run causing high-gain saturation in the whole camera, this 
-extractor apparently fails since only dead pixels which cannot produced a saturated signal, are taken into account 
-in the peak search. For this special case, we modified {\textit{\bf MExtractFixedWindowPeakSearch}} 
+extractor apparently fails since only dead pixels are taken into account in the peak search
+ which cannot produce a saturated signal. 
+For this special case, we modified {\textit{\bf MExtractFixedWindowPeakSearch}} 
 such to define the peak search window as the one starting from the mean position of the first saturating slice.
 \par
@@ -703 +704 @@
 \label{fig:dfsketch}
 \end{figure}
+
+\subsubsection{Digital Filter with Global Peak Search}
+
+This extractor is implemented in the MARS-class {\textit{\bf MExtractTimeAndChargeDigitalFilterPeakSearch}}.
+
+The idea of this extractor is to combine {\textit{\bf MExtractFixedWindowPeakSearch}} and 
+{\textit{\bf MExtractTimeAndChargeDigitalFilter}} in order to correct for coherent movements in arrival time 
+for all pixels and still use the digital filter fit capabilities. 
+ \par
+
+In a first loop, it fixes a reference point defined as the highest sum of 
+consecutive non-saturating FADC slices in a (smaller) peak-search window.
+\par
+In a second loop over the pixels, 
+it uses the digital filter algorithm within a reduced extraction window. 
+It loops twice over all pixels in every event, because it has to find the reference point, first. 
+
+As in the case of  {\textit{\bf MExtractFixedWindowPeakSearch}}, for a high intensity calibration run 
+causing high-gain saturation in the whole camera, this 
+extractor apparently fails since only dead pixels
+are taken into account in the peak search  which cannot produce a saturated signal. 
+
+\par
+For this special case, the extractor then defines the peak search window 
+as the one starting from the mean position of the first saturating slice.
+\par
+The following  adjustable parameters have to be set from outside, additionally to the ones to be 
+set in {\textit{\bf MExtractTimeAndChargeDigitalFilter}}: 
+\begin{description}
+\item[Peak Search Window:\xspace] Defines the ``sliding window'' size within which the peaking sum is 
+searched for (default: 2 slices)
+\item[Offset left from Peak:\xspace] Defines the left offset of the start of the extraction window w.r.t. the 
+starting point of the obtained peak search window (default: 3 slices)
+\item[Offset right from Peak:\xspace] Defines the right offset of the  of the extraction window w.r.t. the 
+starting point of the obtained peak search window (default: 3 slices)
+\item[Limit for high gain failure events:\xspace] Defines the limit of the number of events which failed 
+to be in the high-gain window before the run is rejected.
+\item[Limit for low gain failure events:\xspace] Defines the limit of the number of events which failed 
+to be in the low-gain window before the run is rejected.
+\end{description}
+
+In principle, the ``offsets'' can be chosen very small, because both showers and calibration pulses spread 
+over a very small time interval, typically less than one FADC slice. However, the MAGIC DAQ produces 
+artificial jumps of two FADC slices from time to time\footnote{in 5\% of the events per pixel in December 2004}, 
+so the 3 slices are made in order not to reject these pixels already with the extractor.  
 
 \subsubsection{Real Fit to the Expected Pulse Shape }
@@ -804 +850 @@
 \item SetWeightsFile(``calibration\_weights4\_blue\_logaintest.dat'');
 \suspend{enumerate}
+\item[MExtractTimeAndChargeDigitalFilterPeakSearch]: with the following initialization:
+\resume{enumerate}
+\item SetWeightsFile(``calibration\_weights\_UV.dat'');
+\suspend{enumerate}
 \item[``Real Fit'']: (not yet implemented, one try)
 \resume{enumerate}