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File indexing completed on 2025-10-17 07:58:53
0001 // This file is part of the ACTS project. 0002 // 0003 // Copyright (C) 2016 CERN for the benefit of the ACTS project 0004 // 0005 // This Source Code Form is subject to the terms of the Mozilla Public 0006 // License, v. 2.0. If a copy of the MPL was not distributed with this 0007 // file, You can obtain one at https://mozilla.org/MPL/2.0/. 0008 0009 #pragma once 0010 0011 #include "Acts/EventData/TrackParameters.hpp" 0012 #include "Acts/MagneticField/MagneticFieldContext.hpp" 0013 #include "Acts/Utilities/Result.hpp" 0014 #include "Acts/Vertexing/AdaptiveGridTrackDensity.hpp" 0015 #include "Acts/Vertexing/DummyVertexFitter.hpp" 0016 #include "Acts/Vertexing/IVertexFinder.hpp" 0017 #include "Acts/Vertexing/Vertex.hpp" 0018 #include "Acts/Vertexing/VertexingOptions.hpp" 0019 0020 #include <unordered_map> 0021 0022 namespace Acts { 0023 0024 /// @class AdaptiveGridDensityVertexFinder 0025 /// @brief Vertex finder that makes use of a track density grid. 0026 /// Each single track is modelled as a 2-dim Gaussian distribution grid 0027 /// in the d0-z0 plane, but only the overlap with the z-axis (i.e. a 1-dim 0028 /// density vector) needs to be calculated. All track contributions along the 0029 /// beam axis (main density vector) are superimposed and the z-value of the bin 0030 /// with the highest track density is returned as a vertex candidate. 0031 /// Unlike the GridDensityVertexFinder, this seeder implements an adaptive 0032 /// version where the density grid grows bigger with added tracks. 0033 class AdaptiveGridDensityVertexFinder final : public IVertexFinder { 0034 public: 0035 /// Type alias for the density map used in adaptive grid vertex finding 0036 using DensityMap = AdaptiveGridTrackDensity::DensityMap; 0037 0038 /// @brief The Config struct 0039 struct Config { 0040 ///@param gDensity The grid density 0041 explicit Config(const AdaptiveGridTrackDensity& gDensity) 0042 : gridDensity(gDensity) {} 0043 0044 // The grid density object 0045 /// Grid density calculator for track density estimation 0046 AdaptiveGridTrackDensity gridDensity; 0047 0048 // Cache the main grid and the density contributions (trackGrid and z-bin) 0049 // for every single track. 0050 // This option enables the possibility to calculate the entire main grid 0051 // only once in the first iteration. If tracks are removed from the track 0052 // collection, the individual track density contributions to the main grid 0053 // can just be removed without calculating the entire grid from scratch. 0054 /// Flag to enable caching of grid state for efficient track removal 0055 bool cacheGridStateForTrackRemoval = true; 0056 0057 // Maximum d0 impact parameter significance to use a track 0058 /// Maximum d0 impact parameter significance threshold 0059 double maxD0TrackSignificance = 3.5; 0060 // Maximum z0 impact parameter significance to use a track 0061 /// Maximum z0 impact parameter significance threshold 0062 double maxZ0TrackSignificance = 12.; 0063 // The actual corresponding cut values in the algorithm 0064 /// Squared d0 significance cut value for track selection 0065 double d0SignificanceCut = maxD0TrackSignificance * maxD0TrackSignificance; 0066 /// Squared z0 significance cut value for track selection 0067 double z0SignificanceCut = maxZ0TrackSignificance * maxZ0TrackSignificance; 0068 /// Flag indicating whether to estimate seed width 0069 bool estimateSeedWidth = false; 0070 0071 // Function to extract parameters from InputTrack 0072 /// Function to extract track parameters from InputTrack 0073 InputTrack::Extractor extractParameters; 0074 }; 0075 0076 /// @brief The State struct 0077 /// 0078 /// Only needed if cacheGridStateForTrackRemoval == true 0079 struct State { 0080 // Map from the z bin values to the corresponding track density 0081 /// Main density map storing cumulative track density per z-bin 0082 DensityMap mainDensityMap; 0083 0084 // Map from input track to corresponding track density map 0085 /// Map storing individual track density contributions 0086 std::unordered_map<InputTrack, DensityMap> trackDensities; 0087 0088 // Store tracks that have been removed from track collection. These 0089 // tracks will be removed from the main grid 0090 /// Vector of tracks to be removed from density calculation 0091 std::vector<InputTrack> tracksToRemove; 0092 0093 /// Flag indicating whether the state has been initialized 0094 bool isInitialized = false; 0095 }; 0096 0097 /// @brief Function that finds single vertex candidate 0098 /// 0099 /// @param trackVector Input track collection 0100 /// @param vertexingOptions Vertexing options 0101 /// @param anyState The state object to cache the density grid 0102 /// and density contributions of each track, to be used 0103 /// if cacheGridStateForTrackRemoval == true 0104 /// 0105 /// @return Vector of vertices, filled with a single 0106 /// vertex (for consistent interfaces) 0107 Result<std::vector<Vertex>> find( 0108 const std::vector<InputTrack>& trackVector, 0109 const VertexingOptions& vertexingOptions, 0110 IVertexFinder::State& anyState) const override; 0111 0112 IVertexFinder::State makeState( 0113 const Acts::MagneticFieldContext& /*mctx*/) const override { 0114 return IVertexFinder::State{State{}}; 0115 } 0116 0117 void setTracksToRemove( 0118 IVertexFinder::State& anyState, 0119 const std::vector<InputTrack>& removedTracks) const override { 0120 auto& state = anyState.template as<State>(); 0121 state.tracksToRemove = removedTracks; 0122 } 0123 0124 /// @brief Constructor for user-defined InputTrack type 0125 /// 0126 /// @param cfg Configuration object 0127 explicit AdaptiveGridDensityVertexFinder(const Config& cfg) : m_cfg(cfg) {} 0128 0129 private: 0130 /// @brief Checks if a track passes the selection criteria for seeding 0131 /// 0132 /// @param trk The track 0133 /// 0134 /// @return Bool track passes selection 0135 bool doesPassTrackSelection(const BoundTrackParameters& trk) const; 0136 0137 // The configuration object 0138 const Config m_cfg; 0139 }; 0140 0141 } // namespace Acts
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