Study of the material of the ATLAS inner detector for Run 2 of the LHC
- Aaboud, Morad et al
- arXiv:1707.02826CERN-EP-2017-081
| The $r$--$z$ cross-section view of the layout of a quadrant of the ATLAS inner detector for Run~2. The top panel shows the whole inner detector, whereas the bottom-left panel shows a magnified view of the pixel detector region. Compared to Run~1, the IBL (shown in red in the bottom-left panel) and its services, together with the new beam pipe, were added. |
| $r < 600$ \millimeter$20~\millimeter< r < 75$ \millimeter |
| The differential number of radiation lengths as a function of the radius, $\varDelta N_{X_{0}}/\varDelta r$, averaged over $|z|<300$~\millimeter \subref{fig:GeoModelMap:matmap_unzoom} for $r < 600$ \millimeter and \subref{fig:GeoModelMap:matmap_zoom} for $20~\millimeter< r < 75$ \millimeter for the \emph{original} geometry and the \emph{updated} geometry. The simulated material is sampled for each $z$-position along a straight radial path (perpendicular to the beam line).Caption not extracted |
| Beam PipeIPT |
| IBLIST |
| Number of radiation lengths as a function of the $z$-coordinate for different radial sections for the \emph{original} geometry and the \emph{updated} geometry.Caption not extracted |
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| The $r$--$z$ distribution of the differential number of radiation lengths, $\varDelta N_{X_{0}}/\varDelta r$, for the \emph{updated} geometry model of a quadrant of the inner detector barrel region of the pixel detector and the SCT. The simulated material is sampled for each $z$-position along a straight radial path (perpendicular to the beam line). |
| The amount of material associated with nuclear interactions, $N_{\lambda_{I}} = \int\!{\mathrm d}s\,\lambda_{I}^{-1}$, averaged over $\phi$, as a function of $\eta$ in the positive $\eta$ range integrated up to $r=250~\millimeter$ for the \emph{updated} geometry model. The simulated material is sampled from $z=0$ along a straight path with fixed $\phi$. The material within the inner detector is shown separately for the regions $r<27~\millimeter$, $27~\millimeter<r<45~\millimeter$, $45~\millimeter<r<150~\millimeter$ and $150~\millimeter<r<250~\millimeter$, corresponding approximately to the beam pipe, IBL, pixel barrel and pixel service region, respectively. The statistical uncertainty in each bin is negligible. |
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| Distribution of hadronic-interaction vertex candidates in $|\eta|<2.4$ and $|z|<400~\millimeter$ for data and the \textsc{Pythia~8} MC simulation with the \emph{updated} geometry model. \subref{fig:hadInt_data_map_XY_zoom}, \subref{fig:hadInt_py8_map_XY_zoom} The $x$--$y$ view zooming-in to the beam pipe, IPT, IBL staves and IST, and \subref{fig:hadInt_data_map_XY}, \subref{fig:hadInt_py8_map_XY} of the pixel detector. Some differences between the data and the \textsc{Pythia~8} MC simulation, observed at the position of some of the cooling pipes in the next-to-innermost layer (PIX1), are due to mis-modelling of the coolant fluids, as discussed in Ref.~\cite{PERF-2011-08}.Caption not extracted |
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| \subref{fig:bp_prof} The $r$--$\phi$ profile of hadronic interaction candidates at the beam pipe, fitted with a sinusoidal curve to determine the shift of the pipe from the origin of the ATLAS coordinate system in the $x$--$y$ plane. In the ratio plot in the bottom panel, a small sinusoidal deviation in data from the fit is observed. This may be reflect a slight misalignment of the beam pipe with respect to the $z$-axis, but this does not affect the result of the analysis. \subref{fig:compare_R_corr_twoMCs_IBL_2} Comparison of the radial distribution of hadronic interaction candidates to the \textsc{Epos} \emph{updated} geometry model before and after the radial offset correction to the data for each barrel layer within $20~\millimeter<r<45~\millimeter$.Caption not extracted |
| Comparison of the $z$-distribution of the rate of hadronic interaction candidates at the beam pipe in data and \textsc{Epos} MC simulation with the \emph{updated} geometry model. The band shown in the bottom panel indicates statistical uncertainty of the MC simulation. |
| Comparison of the $z$-distribution of the rate of hadronic interaction candidates at the beam pipe in data and \textsc{Epos} MC simulation with the \emph{updated} geometry model. The band shown in the bottom panel indicates statistical uncertainty of the MC simulation.$-400~\millimeter < z < -40~\millimeter$Comparison of the $z$-distribution of the rate of hadronic interaction candidates at the beam pipe in data and \textsc{Epos} MC simulation with the \emph{updated} geometry model. The band shown in the bottom panel indicates statistical uncertainty of the MC simulation.$|z| < 40~\millimeter$ |
| Comparison of the $z$-distribution of the rate of hadronic interaction candidates at the beam pipe in data and \textsc{Epos} MC simulation with the \emph{updated} geometry model. The band shown in the bottom panel indicates statistical uncertainty of the MC simulation.$40~\millimeter < z < 400~\millimeter$Comparison of the $z$-distribution of the rate of hadronic interaction candidates at the beam pipe in data and \textsc{Epos} MC simulation with the \emph{updated} geometry model. The band shown in the bottom panel indicates statistical uncertainty of the MC simulation.Comparison between data and simulation of the $r$-distribution of the hadronic interaction candidates at the beam pipe ($22.5~\millimeter<r<26.5~\millimeter$) in different $z$ sections. The MC simulation is normalised to the data using the rate at $|z|>40~\millimeter$. An excess is observed at the outer surface of the beam pipe for $|z|<40~\millimeter$. |
| Comparison of the $z$-distribution of the rate of hadronic interaction candidates at the beam pipe in data and \textsc{Epos} MC simulation with the \emph{updated} geometry model. The band shown in the bottom panel indicates statistical uncertainty of the MC simulation.Caption not extracted |
| $20~\millimeter<r<75$~\millimeter$45$~\millimeter$<r<150$~\millimeter |
| Comparison of the radial distribution of hadronic interaction candidates between data and simulation (\emph{original} and \emph{updated} simulations) for \subref{fig:compare_R_corr_twoMCs_IBL} $20$~\millimeter$ < r < 75$ mm and \subref{fig:compare_R_corr_twoMCs_Pixel} $45$~\millimeter $< r <$ 150 mm.Caption not extracted |
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| Conversion vertex position distributions for \textsc{Pythia~8} simulation with the \emph{updated} geometry model compared to data, including \subref{fig:conv:bp_z} the conversion vertex $z$-position distribution in the beam-pipe radial region and the conversion vertex radial distributions in \subref{fig:conv:bp_r} the beam-pipe and IBL region, \subref{fig:conv:pix_r} region up to and including the third pixel layer and \subref{fig:conv:sct_r} region between the PSF second SCT layer.Caption not extracted |
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| Track-extension efficiency as a function of \subref{fig:SCTExt_Eta_DataEposPythia_Diff} $\eta$ and \subref{fig:SCTExt_Pt_DataEposPythia_Diff} $\pt$ of the tracklets in a comparison between data, \textsc{Pythia~8} and \textsc{Epos}.Caption not extracted |
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| Distribution of the vertex vectorial sum of \pt in hadronic interaction candidates \subref{fig:compare_h1_sumpT_BP_all} at the beam pipe in $22.5~\millimeter<r<26.5~\millimeter$, and \subref{fig:compare_h1_sumpT_BLayer_all} at the innermost pre-existing pixel layer (PIX1) in $45~\millimeter<r<75~\millimeter$. \subref{fig:compare_R_SCT_Epos} Radial distribution of hadronic interaction candidates in $150~\millimeter<r<400~\millimeter$. Background rates are not weighted for the \textsc{Epos} MC simulation. \subref{fig:compare_h1_minOpAng_gap1_all_Epos} Distribution of the cosine of the opening angle between two tracks in the laboratory frame $\cos(\theta_{\mathrm{op}})$ for hadronic interaction candidates within the material gap at $73~\millimeter<r<83~\millimeter$ (Gap1) where fake vertices and in-flight decays are enhanced. Background rates are not weighted for the \textsc{Epos} MC simulation. The band shown in \subref{fig:compare_h1_sumpT_BP_all}, \subref{fig:compare_h1_sumpT_BLayer_all} and \subref{fig:compare_h1_minOpAng_gap1_all_Epos} indicates the statistical uncertainty of the MC simulation.Caption not extracted |
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| \subref{fig:effratio} The estimated data-to-MC ratio of reconstruction efficiency and its uncertainty as a function of vertex radius. \subref{fig:compare_R_corr_distorted} Radial distribution of hadronic interaction candidates at the IBL region ($30~\millimeter<r<40~\millimeter$) for the data and the \textsc{Pythia~8} MC simulation with the \emph{updated} geometry model, together with the ``IBL $+10\%$'' and ``IBL $-10\%$'' distorted geometry samples listed in Table~\ref{tbl:mc_lists}.Caption not extracted |
| The sum of \NormSctExtEff (normalised track-extension efficiency in the nominal geometry and in the modified geometries) and $\varDelta{N}^{\mathrm{mod-nom}}_{\lambda_{I}}$ (number of nuclear interaction lengths in the nominal geometry and in the modified geometries). A modified geometry results in different values of $\varDelta{N}^{\mathrm{mod-nom}}_{\lambda_{I}}$ over several $\eta$ bins. The solid red lines are envelopes described by the curves $\pm (0.004 + 0.04 \cdot \varDelta{N}^{\mathrm{mod-nom}}_{\lambda_{I}})$. |
| The difference between the track-extension efficiency measured in data and in simulation, $\varDelta\SctExtEff^{\mathrm{Data}-\mathrm{MC}}(\eta)$, is shown together with the uncertainties. The total uncertainty includes the uncertainty from fake tracklets, the uncertainty from the particle composition and $\pt$-dependence, and the statistical uncertainty; these are all summed in quadrature. The particle composition uncertainty overwhelmingly dominates the total uncertainty and thus the vertical extent of its uncertainty band is very close to that of the total uncertainty. |
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| Unfolded transverse impact parameter resolution measured in data as a function of $\pt$, compared to the simulation using the \emph{original} and \emph{updated} geometry models. Uncertainties are only statistical. |
| The excess amount of material between the pixel and SCT detector associated with nuclear interactions in data, $\varDelta N_{\lambda_{I}}^{\mathrm{Data-MC}}$, based on the track-extension efficiency measurement. The uncertainties shown include the uncertainty from fake pixel-tracklets, the uncertainty from the particle composition and $\pt$-dependence, the uncertainty from the material location and the statistical uncertainties. |
| The $r$--$z$ distribution of differential number of nuclear interaction length, $\varDelta N_{\lambda_{I}}/\varDelta r$, for the \emph{updated} geometry model of the quadrant of the inner detector barrel region of the pixel detector and the SCT. |
| The amount of material associated to electromagnetic interactions, $N_{X_{0}} = \int\!{\mathrm d}s\,X_{0}^{-1}$ as a function of $\eta$ in the positive $\eta$ range integrated up to $r=250~\millimeter$ of the \emph{updated} geometry model. Regions are categorised into $r<27~\millimeter$, $27~\millimeter<r<45~\millimeter$, $45~\millimeter<r<150~\millimeter$ and $150~\millimeter<r<250~\millimeter$, corresponding to the beam pipe, IBL, pixel barrel and pixel service region, respectively. |
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| Distribution of the hadronic-interaction vertex candidates within $|\eta|<2.4$ and $|z|<400~\mathrm{mm}$ in $r$--$z$ view for \subref{fig:hadInt_data_map_RZ} data and \subref{fig:hadInt_py8_map_RZ} \textsc{Pythia~8} simulation with the \emph{updated} geometry model. The integral path is taken in the radial direction for each $z$-position. The vertex radius is corrected for the radial offset for the data.Caption not extracted |
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| Distribution of hadronic-interaction vertex candidates within $|\eta|<2.4$ and $|z|<400~\mathrm{mm}$, without radial offset correction in $r$--$\phi$ view for \subref{fig:hadInt_data_map_Rphi} data and \subref{fig:hadInt_py8_map_Rphi} \textsc{Pythia~8} simulation with the \emph{updated} geometry model. The vertex radius is not corrected for the radial offset for the data.Caption not extracted |
| Distribution of hadronic-interaction vertex candidates in $\phi$ at the beam pipe ($22.5~\millimeter<r<26.5~\millimeter$) in data compared to the \textsc{Epos} MC simulation sample for the \emph{updated} geometry. The band in the ratio plots in the bottom panel indicates statistical uncertainty of the MC simulation samples. |
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| Distribution of hadronic-interaction vertex candidates in $z$ and $\phi$ at the IPT ($28.5~\millimeter<r<30.0~\millimeter$) in data compared to the \textsc{Epos} MC simulation sample for the \emph{updated} geometry. The band in the ratio plots in the bottom panel indicates statistical uncertainty of the MC simulation samples. |
| Distribution of hadronic-interaction vertex candidates in $z$ and $\phi$ at the IBL ($30~\millimeter<r<40~\millimeter$) in data compared to the \textsc{Epos} MC simulation sample for the \emph{updated} geometry. The band in the ratio plots in the bottom panel indicates statistical uncertainty of the MC simulation samples. |
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| Distribution of hadronic-interaction vertex candidates in $z$ and $\phi$ at the IST ($41.5~\millimeter<r<45~\millimeter$) in data compared to the \textsc{Epos} MC simulation sample for the \emph{updated} geometry. The band in the ratio plots in the bottom panel indicates statistical uncertainty of the MC simulation samples. The deficit of the data at $z=0~\mathrm{mm}$ is due to difference of classification of radial sections between data and the MC simulation reflecting the radial offset. The counterpart yield is observed in Figure~\ref{fig:compare_h1_Z_IBL_all}. |
| Distribution of hadronic-interaction vertex candidates in $z$ and $\phi$ at the PIX1 ($45~\millimeter<r<75~\millimeter$) in data compared to the \textsc{Epos} MC simulation sample for the \emph{updated} geometry. The band in the ratio plots in the bottom panel indicates statistical uncertainty of the MC simulation samples. |
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| Distribution of hadronic-interaction vertex candidates in $z$ and $\phi$ at the PIX2 ($83~\millimeter<r<110~\millimeter$) in data compared to the \textsc{Epos} MC simulation sample for the \emph{updated} geometry. The band in the ratio plots in the bottom panel indicates statistical uncertainty of the MC simulation samples.Caption not extracted |
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| Distribution of hadronic-interaction vertex candidates in $z$ and $\phi$ at the PIX3 ($118~\millimeter<r<145~\millimeter$) in data compared to the \textsc{Epos} MC simulation sample for the \emph{updated} geometry. The band in the ratio plots in the bottom panel indicates statistical uncertainty of the MC simulation samples. |
| Distribution of hadronic-interaction vertex candidates in $z$ and $\phi$ at the PSF ($180~\millimeter<r<225~\millimeter$) in data compared to the \textsc{Epos} MC simulation sample for the \emph{updated} geometry. The band in the ratio plots in the bottom panel indicates statistical uncertainty of the MC simulation samples. |
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| Distribution of hadronic-interaction vertex candidates in $z$ and $\phi$ at the PST ($225~\millimeter<r<240~\millimeter$) in data compared to the \textsc{Epos} MC simulation sample for the \emph{updated} geometry. The band in the ratio plots in the bottom panel indicates statistical uncertainty of the MC simulation samples.Caption not extracted |
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| Distribution of hadronic-interaction vertex candidates in $z$ and $\phi$ at the SCT-ITE ($245~\millimeter<r<265~\millimeter$) in data compared to the \textsc{Epos} MC simulation sample for the \emph{updated} geometry. The band in the ratio plots in the bottom panel indicates statistical uncertainty of the MC simulation samples. |
| Distribution of hadronic-interaction vertex candidates in $z$ and $\phi$ at the SCT1 ($276~\millimeter<r<320~\millimeter$) in data compared to the \textsc{Epos} MC simulation sample for the \emph{updated} geometry. The band in the ratio plots in the bottom panel indicates statistical uncertainty of the MC simulation samples. |
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| Distribution of hadronic-interaction vertex candidates in $z$ and $\phi$ at the SCT2 ($347~\millimeter<r<390~\millimeter$) in data compared to the \textsc{Epos} MC simulation sample for the \emph{updated} geometry. The band in the ratio plots in the bottom panel indicates statistical uncertainty of the MC simulation samples.Caption not extracted |
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| Conversion vertex $z$-position distributions for \textsc{Pythia~8} simulation compared to data in the PSF and PST radial region. |
| Track-extension efficiency as a function of $\phi$ of the tracklets in a comparison between data, \textsc{Pythia~8} and \textsc{Epos}. |
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| Track-extension efficiency as a function of $\eta$ and $\phi$ of the tracklets in a comparison between \subref{fig:SCTExt_EtaPhi_DataPythia_Diff} data and \textsc{Pythia~8} and between \subref{fig:SCTExt_EtaPhi_DataEpos_Diff} data and \textsc{Epos}.Caption not extracted |
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| Track-Extension efficiency exclusive for pions, protons, kaons, electrons, muons, weakly decaying strange baryons ($\Sigma^{\pm}$, $ \Xi^{-}$, $\Omega^{-}$ and their antiparticles) or fake tracklets as a function of \subref{fig:SCTExt_Particles_Pythia_Eta} $\eta$ and \subref{fig:SCTExt_Particles_Pythia_Pt} $\pt$ in simulation.Caption not extracted |
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| Fraction of reconstucted tracklets associated with pions, protons, kaons, electrons, muons, weakly decaying strange baryons ($\Sigma^{\pm}$, $ \Xi^{-}$ and $\Omega^{-}$) or fake tracklets with respect to the total number of reconstructed tracklets as a function of \subref{fig:TrackletFraction_Pythia_Eta} $\eta$ and \subref{fig:TrackletFraction_Pythia_Pt} $\pt$ in the \textsc{Pythia~8} simulated sample. |
| Fraction of reconstucted tracklets associated with {pions}, {protons}, {kaons}, {electrons}, {muons}, {weakly decaying strange baryons} ($\Sigma^{\pm}$, $ \Xi^{-}$ and $\Omega^{-}$) or {fake tracklets} with respect to the total number of reconstructed tracklets as a function of \subref{fig:TrackletFraction_Epos_Eta} $\eta$ and \subref{fig:TrackletFraction_Epos_Pt} $\pt$ in the \textsc{Epos} simulated sample. |
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