Changeset 523 in svn for trunk/paper/CommPhysComp
- Timestamp:
- Jul 29, 2009, 3:07:21 PM (15 years ago)
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- trunk/paper/CommPhysComp
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trunk/paper/CommPhysComp/notes.tex
r522 r523 282 282 283 283 The smallest unit for geometrical sampling of the calorimeters is a \textit{tower}; it segments the $(\eta,\phi)$ plane for the energy measurement. No longitudinal segmentation is available in the simulated calorimeters. All undecayed particles, except muons and neutrinos deposit energy in a calorimetric tower, either in \textsc{ecal}, in \textsc{hcal} or \textsc{fcal}. 284 As the detector is assumed to be cylindrical (e.g.\ symmetric in $\phi$ and with respect to the $\eta=0$ plane), the detector card stores the number of calorimetric towers with $\phi=0$ and $\eta>0$ (default: $40$ towers). For a given $\eta$, the size of the $\phi$ segmentation is also specified. Fig.~\ref{fig:calosegmentation} illustrates the default segmentation of the $(\eta,\phi)$ plane.284 As the detector is assumed to be cylindrical (e.g.\ symmetric in $\phi$ and with respect to the $\eta=0$ plane), the detector card stores the number of calorimetric towers with $\phi=0$ and $\eta>0$ (default: $40$ towers). For a given $\eta$, the size of the $\phi$ segmentation is also specified. Fig.~\ref{fig:calosegmentation} illustrates the default calorimeter segmentation, which is common for the electromagnetic and hadronic sections at a given $(\eta,\phi)$. 285 285 286 286 \begin{figure}[!ht] … … 305 305 \caption{Default location of the very forward detectors, including \textsc{zdc}, \textsc{rp220} and \textsc{fp420} in the \textsc{lhc} beamline. 306 306 Incoming (beam 1, red) and outgoing (beam 2, black) beams on one side of the fifth interaction point (\textsc{ip}5, $s=0~\textrm{m}$ on the plot). 307 The Zero Degree Calorimeter is located in perfect alignment with the beamline axis at the interaction point, at $140~\textrm{m}$, the beam paths are separated. The forward taggers are near-beam detectors located at $220~\textrm{m}$ and $420~\textrm{m}$. Beamline simulation with \textsc{Hector}~\citep{bib:Hector}. }307 The Zero Degree Calorimeter is located in perfect alignment with the beamline axis at the interaction point, at $140~\textrm{m}$, the beam paths are separated. The forward taggers are near-beam detectors located at $220~\textrm{m}$ and $420~\textrm{m}$. Beamline simulation with \textsc{Hector}~\citep{bib:Hector}. All very forward detectors are located symmetrically around the interaction point. } 308 308 \label{fig:fdets} 309 309 \end{center} … … 406 406 Generator-level muons entering the detector acceptance are considered as candidates for the analysis level. 407 407 The acceptance is defined in terms of a transverse momentum threshold to be overpassed that should be computed using the chosen geometry of the detector and the magnetic field considered (default : $p_T > 10~\textrm{GeV}/c$) and of the pseudorapidity coverage of the muon system (default: $-2.4 \leq \eta \leq 2.4$). 408 The application of the detector resolution on the muon momentum depends on a Gaussian smearing of the $p_T$ variable\footnote{\texttt{[code]} See the \texttt{SmearMuon} method.}. Neither $\eta$ nor $\phi$ variables are modified beyond the calorimeters: no additional magnetic field is applied. Multiple scattering is neglected. This implies that low energy muons have in \textsc{Delphes} a better resolution than in a real detector. Furthermore, muons leave no deposit in calorimeters. 408 The application of the detector resolution on the muon momentum depends on a Gaussian smearing of the $p_T$ variable\footnote{\texttt{[code]} See the \texttt{SmearMuon} method.}. Neither $\eta$ nor $\phi$ variables are modified beyond the calorimeters: no additional magnetic field is applied. Multiple scattering is neglected. This implies that low energy muons have in \textsc{Delphes} a better resolution than in a real detector. Furthermore, muons leave no deposit in calorimeters. At last, the particles which might leak out of the calorimeters into the muon systems (\textit{punch-through}) will not be see 409 n as muon candidates in \textsc{Delphes}. 409 410 410 411 \subsubsection*{Charged lepton isolation} … … 510 511 $ \tau^- \rightarrow \mu^- \ \bar \nu_\mu \ \nu_\tau$ & $17.4\%$ \\ 511 512 \multicolumn{2}{l}{\textbf{Hadronic decays}}\\ 512 $ \tau^- \rightarrow h^-\ n\times h^\pm \ m\times h^0\ \nu_\tau$ & $64.7\%$ \\513 $ \tau^- \rightarrow h^-\ m\times h^0\ \nu_\tau$ & $50.1\%$ \\514 $ \tau^- \rightarrow h^-\ h^+ h^- m\times h^0\ \nu_\tau$ & $14.6\%$ \\513 $ \tau^- \rightarrow h^-\ (n\times h^\pm) \ (m\times h^0) \ \nu_\tau$ & $64.7\%$ \\ 514 $ \tau^- \rightarrow h^-\ (m\times h^0) \ \nu_\tau$ & $50.1\%$ \\ 515 $ \tau^- \rightarrow h^-\ h^+ h^- (m\times h^0) \ \nu_\tau$ & $14.6\%$ \\ 515 516 \hline 516 517 \end{tabular} … … 609 610 \end{equation} 610 611 The \textit{true} missing transverse energy, i.e.\ at generator-level, is calculated as the opposite of the vector sum of the transverse momenta of all visible particles -- or equivalently, to the vector sum of invisible particle transverse momenta. 611 In a real experiment, calorimeters measure energy and not momentum. Any problem affecting the detector (dead channels, misalignment, noisy towers, cracks) worsens directly the measured missing transverse energy $\overrightarrow {E_T}^\textrm{miss}$. In this document, \textsc{met} is based on the calorimetric towers and only muons and neutrinos are not taken into account for its evaluation\footnote{However, as tracks and calorimetric towers are available in the output file, the missing transverse energy can always be reprocessed a posteriori }:612 In a real experiment, calorimeters measure energy and not momentum. Any problem affecting the detector (dead channels, misalignment, noisy towers, cracks) worsens directly the measured missing transverse energy $\overrightarrow {E_T}^\textrm{miss}$. In this document, \textsc{met} is based on the calorimetric towers and only muons and neutrinos are not taken into account for its evaluation\footnote{However, as tracks and calorimetric towers are available in the output file, the missing transverse energy can always be reprocessed a posteriori. }: 612 613 \begin{equation} 613 614 \overrightarrow{E_T}^\textrm{miss} = - \sum^\textrm{towers}_i \overrightarrow{E_T}(i)
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