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01/10/05 11:35:54 (20 years ago)
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  • trunk/MagicSoft/TDAS-Extractor/Algorithms.tex

    r5759 r5763  
    280280
    281281\begin{description}
    282 \item[Time Extraction Type:\xspace] The position of the maximum can be chosen or the
    283 position of the half maximum at the rising edge of the pulse (default).
    284 \item[Charge Extraction Type:\xspace] The amplitude of the maximum can be chosen (default) or the
    285 integrated spline between maximum position minus rise time (default: 1.5 slices) and maximum position plus
    286 fall time (default: 4.5 slices). The low-gain signal integrates half a slice more at the rising
    287 falling part of the
    288 signal.
     282\item[Charge Extraction Type:\xspace] The amplitude of the spline maximum can be chosen while the position
     283of the maximum is returned as arrival time. This type is fast. \\
     284Otherwise, the integrated spline between maximum position minus rise time (default: 1.5 slices)
     285and maximum position plus fall time (default: 4.5 slices) is taken as signal and the position of the
     286half maximum is returned as arrival time (default).
     287The low-gain signal stretches the rise and fall time by a stretch factor (default: 1.5). This type
     288is slower, but more precise. The charge integration resolution is 0.1 FADC slices.
    289289\item[Rise Time and Fall Time:\xspace] Can be adjusted for the integration charge extraction type.
    290290\item[Resolution:\xspace] Defined as the maximum allowed difference between the calculated half maximum value and
    291291the computed spline value at the arrival time position. Can be adjusted for the half-maximum time extraction
    292292type.
     293\item[LoGainSignalStretch:\xspace] Can be adjusted to account for the bigger rise and fall time in the
     294low-gain as compared to the high gain pulses (default: 1.5)
    293295\end{description}
    294296
     
    305307\item{The normalized signal shape has to be independent of the signal amplitude.}
    306308\item{The noise properties have to be independent of the signal amplitude.}
     309\item{The noise auto-correlation matrix does not change its form significantly with time.}
    307310\end{itemize}
    308311
     
    313316\end{equation}
    314317
    315 where $b(t)$ is the time dependent noise distribution. For small time shifts $\tau$ the time dependence can be linearized by the use of a Taylor expansion:
     318where $b(t)$ is the time dependent noise distribution. For small time shifts $\tau$ (usually smaller than
     319one FADC slice width),
     320the time dependence can be linearized by the use of a Taylor expansion:
    316321
    317322\begin{equation} \label{shape_taylor_approx}
     
    350355\end{equation}
    351356
    352 Taking into account that $\boldsymbol{B}$ is a symmetric matrix, this leads to the following two equations for the estimated amplitude $\overline{E}$ and the estimation for the product of amplitude and time offset $\overline{E\tau}$:
     357Taking into account that $\boldsymbol{B}$ is a symmetric matrix, this leads to the following
     358two equations for the estimated amplitude $\overline{E}$ and the estimation for the product of amplitude
     359and time offset $\overline{E\tau}$:
    353360
    354361\begin{eqnarray}
     
    369376
    370377
    371 Thus $\overline{E}$ and $\overline{E\tau}$ are given by a weighted sum of the discrete measurements $y_i$ with the digital filtering weights for the amplitude, $w_{\text{amp},i}$, and time shift, $w_{\text{time},i}$.
    372 
    373 Because of the truncation of the Taylor series in equation (\ref{shape_taylor_approx}) the above results are only valid for vanishing time offsets $\tau$. For non-zero time offsets one has to iterate the problem using the time shifted signal shape $g(t-\tau)$.
     378Thus $\overline{E}$ and $\overline{E\tau}$ are given by a weighted sum of the discrete measurements $y_i$
     379with the digital filtering weights for the amplitude, $w_{\text{amp},i}$, and time shift, $w_{\text{time},i}$.
     380
     381Because of the truncation of the Taylor series in equation (\ref{shape_taylor_approx}) the above results are
     382only valid for vanishing time offsets $\tau$. For non-zero time offsets one has to iterate the problem using
     383the time shifted signal shape $g(t-\tau)$.
    374384
    375385The covariance matrix $\boldsymbol{V}$ of $\overline{E}$ and $\overline{E\tau}$ is given by:
    376386
    377387\begin{equation}
    378 \left(\boldsymbol{V}^{-1}\right)_{i,j}=\frac{1}{2}\left(\frac{\partial^2 \chi^2(E, E\tau)}{\partial \alpha_i \partial \alpha_j} \right) \quad \text{with} \quad \alpha_i,\alpha_j \in {E, E\tau} \ .
     388\left(\boldsymbol{V}^{-1}\right)_{i,j}=\frac{1}{2}\left(\frac{\partial^2 \chi^2(E, E\tau)}{\partial \alpha_i \partial \alpha_j} \right) \quad \text{with} \quad \alpha_i,\alpha_j \in \{E, E\tau\} \ .
    379389\end{equation}
    380390
     
    388398
    389399\begin{equation}\label{of_noise_time}
    390 E^2 \cdot \sigma_{\tau}^2=\boldsymbol{V}_{E,E\tau}=\frac{{\boldsymbol{g}}^T\boldsymbol{B}^{-1}{\boldsymbol{g}}}{(\boldsymbol{g}^T \boldsymbol{B}^{-1} \boldsymbol{g})(\dot{\boldsymbol{g}}^T\boldsymbol{B}^{-1}\dot{\boldsymbol{g}}) -(\dot{\boldsymbol{g}}^T\boldsymbol{B}^{-1}\boldsymbol{g})^2} \ .
     400E^2 \cdot \sigma_{\tau}^2=\boldsymbol{V}_{E\tau,E\tau}=\frac{{\boldsymbol{g}}^T\boldsymbol{B}^{-1}{\boldsymbol{g}}}{(\boldsymbol{g}^T \boldsymbol{B}^{-1} \boldsymbol{g})(\dot{\boldsymbol{g}}^T\boldsymbol{B}^{-1}\dot{\boldsymbol{g}}) -(\dot{\boldsymbol{g}}^T\boldsymbol{B}^{-1}\boldsymbol{g})^2} \ .
    391401\end{equation}
    392402
     
    419429
    420430
    421 Using the average reconstructed pulpo pulse shape, see figure \ref{fig:pulpo_shape_low}, and the reconstructed noise autocorrelation matrix from a pedestal run with random triggers, the digital filter weights are computed. Figures \ref{fig:w_time_MC_input_TDAS} and \ref{fig:w_amp_MC_input_TDAS} show the parameterization of the amplitude and timing weights for the MC pulse shape as a function of the ...
    422 
     431Using the average reconstructed pulpo pulse shape, as shown in figure \ref{fig:pulpo_shape_low}, and the
     432reconstructed noise autocorrelation matrix from a pedestal run with random triggers, the digital filter
     433weights are computed. Figures \ref{fig:w_time_MC_input_TDAS} and \ref{fig:w_amp_MC_input_TDAS} show the
     434parameterization of the amplitude and timing weights for the MC pulse shape as a function of the ...
     435
     436\par
     437\ldots {\textit{\bf MISSING END OF SENTENCE }} \ldots
     438\par
    423439
    424440\begin{figure}[h!]
     
    441457
    442458\begin{equation}
    443 e_{i_0}=\sum_{i=i_0}^{i=i_0+n-1} w_{\mathrm{amp}}(t_i)y(t_{i+i_0}) \qquad (e\tau)_{i_0}=\sum_{i=i_0}^{i=i_0+n-1} w_{\mathrm{time}}(t_i)y(t_{i+i_0})
     459e_{i_0}=\sum_{i=i_0}^{i_0+n-1} w_{\mathrm{amp}}(t_i)y(t_{i+i_0}) \qquad (e\tau)_{i_0}=\sum_{i=i_0}^{i_0+n-1} w_{\mathrm{time}}(t_i)y(t_{i+i_0})
    444460\end{equation}
    445461
     
    453469
    454470\begin{equation}
    455 E=\sum_{i=i_0^*}^{i=i_0^*+n-1} w_{\mathrm{amp}}(t_i - \tau)y(t_{i+i_0^*}) \qquad E \theta=\sum_{i=i_0^*}^{i=i_0^*+n-1} w_{\mathrm{time}}(t_i - \tau)y(t_{i+i_0^*}) \ .
     471E=\sum_{i=i_0^*}^{i_0^*+n-1} w_{\mathrm{amp}}(t_i - \tau)y(t_{i+i_0^*}) \qquad E \theta=\sum_{i=i_0^*}^{i_0^*+n-1} w_{\mathrm{time}}(t_i - \tau)y(t_{i+i_0^*}) \ .
    456472\end{equation}
    457473
     
    478494%\frac{\sigma^2(b_i)}{\sigma_E^2} = \sum_{i=1}^{n}{g_i^2} - \frac{\sum_{i=1}^{n}{g_i \dot{g}_i}}{\sum_{i=1}^{n}{\dot{g}_i^2}} \ .
    479495%\end{equation}
    480 
    481 
    482 
    483 
    484 
    485496
    486497
     
    490501\includegraphics[totalheight=7cm]{time_sliding.eps}
    491502\end{center}
    492 \caption[Digital filter weights applied.]{Digital filter weights applied to the recorded FADC time slices of one calibration pulse. The left plot shows the result of the applied amplitude weights $e(t_0)=\sum_{i=0}^{i=n-1} w_{\mathrm{amp}}(t_0+i \cdot T_{\text{ADC}})y(t_0+i \cdot T_{\text{ADC}})$ and the right plot shows the result of the applied timing weights $e\tau(t_0)=\sum_{i=0}^{i=n-1} w_{\mathrm{time}}(t_0+i \cdot T_{\text{ADC}})y(t_0+i \cdot T_{\text{ADC}})$ .} \label{fig:amp_sliding}
    493 \end{figure}
    494 
    495 
    496 Figure \ref{fig:shape_fit_TDAS} shows the FADC slices of a single MC event together with the result of a full fit of the input MC pulse shape to the simulated FADC samples together with the result of the numerical fit using the digital filter.
     503\caption[Digital filter weights applied.]{Digital filter weights applied to the recorded FADC time slices of
     504one calibration pulse. The left plot shows the result of the applied amplitude weights
     505$e(t_0)=\sum_{i=0}^{i=n-1} w_{\mathrm{amp}}(t_0+i \cdot T_{\text{ADC}})y(t_0+i \cdot T_{\text{ADC}})$ and
     506the right plot shows the result of the applied timing weights
     507$e\tau(t_0)=\sum_{i=0}^{i=n-1} w_{\mathrm{time}}(t_0+i \cdot T_{\text{ADC}})y(t_0+i \cdot T_{\text{ADC}})$ .}
     508\label{fig:amp_sliding}
     509\end{figure}
     510
     511
     512Figure \ref{fig:shape_fit_TDAS} shows the FADC slices of a single MC event together with the result of a full
     513fit of the input MC pulse shape to the simulated FADC samples together with the result of the numerical fit
     514using the digital filter.
    497515
    498516
     
    501519\includegraphics[totalheight=7cm]{shape_fit_TDAS.eps}
    502520\end{center}
    503 \caption[Shape fit.]{Full fit to the MC pulse shape with the MC input shape and a numerical fit using the digital filter.} \label{fig:shape_fit_TDAS}
    504 \end{figure}
    505 
    506 
    507 
    508 
    509 
     521\caption[Shape fit.]{Full fit to the MC pulse shape with the MC input shape and a numerical fit using the
     522digital filter.} \label{fig:shape_fit_TDAS}
     523\end{figure}
    510524
    511525
     
    533547\includegraphics[totalheight=7cm]{probability_fit_0ns.eps}
    534548\end{center}
    535 \caption[Fit Probability.]{Probability of the fit with the input signal shape to the simulated FADC samples including electronics and NSB noise.} \label{fig:w_amp_MC_input_TDAS.eps}
     549\caption[Fit Probability.]{Probability of the fit with the input signal shape to the simulated FADC samples
     550including electronics and NSB noise.} \label{fig:w_amp_MC_input_TDAS.eps}
    536551\end{figure}
    537552
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