Acts::PathSeeder Class Reference

Seeding algorigthm that extracts the IP parameters and sorts the source links into possible track candidates. More...

#include <Acts/Seeding/PathSeeder.hpp>

Classes
struct	Config
	The nested configuration struct. More...

Public Types
using	IntersectionLookup
	Delegate to find the intersections for the given pivot source link.
using	PathSeed = std::pair<BoundTrackParameters, std::vector<SourceLink>>
	Type alias for path seed consisting of track parameters and source links.
using	PathWidthLookup
	Delegate to provide the path width around the intersection point to pull the source links from the grid.
using	TrackEstimator
	Delegate to estimate the IP parameters and the momentum direction at the reference tracking layer.

Public Member Functions
	PathSeeder (const Config &config)
	Constructor.
	~PathSeeder ()=default
	Destructor.
template<Acts::detail::SourceLinkGrid grid_t, typename container_t>
void	findSeeds (const GeometryContext &gctx, const std::unordered_map< GeometryIdentifier, grid_t > &sourceLinkGridLookup, container_t &seedCollection) const
	Extract the IP parameters and sort the source links into the seeds.

Detailed Description

Seeding algorigthm that extracts the IP parameters and sorts the source links into possible track candidates.

The algorithm to convert the given source links into seeds – pairs of IP parameters and the corresponding source links – as follows: First the source links are sorted into a user-defined grid. Then, iteration over the source links is performed. If a source link is attached to a surface that is in the reference tracking layer, as defined by the user, the IP parameters are estimated and the tracking layers are intersected to construct the core of the "Path". The source links in the subsequent layers are then added to the seed if they lie within the path width of the core. Both the list of source links and the IP parameters are stored in the seed struct.

Template Parameters

axis_t

Type of the axis to bin the source links

Note

The algorithm is designed to be used in the context of a telescope-style geometry. The surfaces are assumed to be planar.

Handling of the rotated surfaces has to happen in the user-defined delegate functions.

Member Typedef Documentation

IntersectionLookup

using Acts::PathSeeder::IntersectionLookup

Initial value:

 
      Delegate<std::vector<std::pair<GeometryIdentifier, Vector2>>(
          const GeometryContext&, const BoundTrackParameters&)>

Delegate to find the intersections for the given pivot source link.

• The geometry context to use
• Track parameters at the reference tracking layer

Returns

Vector of pairs of the geometry identifier and the local intersection point

PathSeed

using Acts::PathSeeder::PathSeed = std::pair<BoundTrackParameters, std::vector<SourceLink>>

Type alias for path seed consisting of track parameters and source links.

PathWidthLookup

using Acts::PathSeeder::PathWidthLookup

Initial value:

 Delegate<std::pair<double, double>(
      const GeometryContext&, const GeometryIdentifier&)>

Delegate to provide the path width around the intersection point to pull the source links from the grid.

• The geometry context to use
• The geometry identifier to use if the path width is varied across different tracking layers

Returns

The path width in the bin0 and bin1 direction defined with respect to the surface normal

TrackEstimator

using Acts::PathSeeder::TrackEstimator

Initial value:

 
      Delegate<std::pair<BoundTrackParameters, BoundTrackParameters>(
          const GeometryContext&, const SourceLink&)>

Delegate to estimate the IP parameters and the momentum direction at the reference tracking layer.

• Geometry context to use
• Pivot source link

Returns

Pair of the track parameters at the IP and the reference tracking layer

Constructor & Destructor Documentation

PathSeeder()

Acts::PathSeeder::PathSeeder ( const Config & config )

explicit

Constructor.

Parameters

config

Configuration for the path seeder

~PathSeeder()

Acts::PathSeeder::~PathSeeder ( )

default

Destructor.

Member Function Documentation

findSeeds()

template<Acts::detail::SourceLinkGrid grid_t, typename container_t>

void Acts::PathSeeder::findSeeds	(	const GeometryContext &	gctx,
		const std::unordered_map< GeometryIdentifier, grid_t > &	sourceLinkGridLookup,
		container_t &	seedCollection ) const

Extract the IP parameters and sort the source links into the seeds.

Parameters

gctx	The geometry context
sourceLinkGridLookup	The lookup table for the source links
seedCollection	The collection of seeds to fill