ActsFatras::Hit Class Reference

A simulation hit on a surface. More...

#include <ActsFatras/EventData/Hit.hpp>

Public Member Functions
	Hit ()=default
	Construct default hit with (mostly) invalid information.
	Hit (Acts::GeometryIdentifier geometryId, Barcode particleId, const Acts::Vector4 &pos4, const Acts::Vector4 &before4, const Acts::Vector4 &after4, std::int32_t index_=-1)
	Construct from four-position and four-momenta.
	Hit (const Hit &)=default
	Copy constructor.
	Hit (Hit &&)=default
	Move constructor.
double	depositedEnergy () const
	Energy deposited by the hit.
Acts::Vector3	direction () const
	Average normalized particle direction vector through the surface.
Acts::Vector3	directionAfter () const
	Normalized particle direction vector the hit.
Acts::Vector3	directionBefore () const
	Normalized particle direction vector before the hit.
const Acts::Vector4 &	fourPosition () const
	Space-time position four-vector.
constexpr Acts::GeometryIdentifier	geometryId () const
	Geometry identifier of the hit surface.
constexpr std::int32_t	index () const
	Hit index along the particle trajectory.
const Acts::Vector4 &	momentum4After () const
	Particle four-momentum after the hit.
const Acts::Vector4 &	momentum4Before () const
	Particle four-momentum before the hit.
Hit &	operator= (const Hit &)=default
	Copy assignment operator.
Hit &	operator= (Hit &&)=default
	Move assignment operator.
constexpr Barcode	particleId () const
	Particle identifier of the particle that generated the hit.
auto	position () const
	Three-position, i.e.
double	time () const
	Time coordinate.

Detailed Description

A simulation hit on a surface.

This is the undigitized, truth hit, i.e. just a recording of the particle state at the surface intersection. Since Fatras is surface-based, the hit position is always constrained to a surface. Depending on the simulated interactions the momentum state before and after might differ and is thus stored as two separate four-vectors.

Constructor & Destructor Documentation

Hit() [1/4]

ActsFatras::Hit::Hit ( )

default

Construct default hit with (mostly) invalid information.

Hit() [2/4]

ActsFatras::Hit::Hit	(	Acts::GeometryIdentifier	geometryId,
		Barcode	particleId,
		const Acts::Vector4 &	pos4,
		const Acts::Vector4 &	before4,
		const Acts::Vector4 &	after4,
		std::int32_t	index_ = -1 )

Construct from four-position and four-momenta.

Parameters

geometryId	Geometry identifier of the surface
particleId	Particle identifier of the particle that created the hit
pos4	Particle space-time four-vector on the surface
before4	Particle four-momentum before the interaction
after4	Particle four-momentum after the interaction
index_	Hit index along the particle trajectory

All quantities are given in the global coordinate system. It is the users responsibility to ensure that the position correspond to a position on the given surface.

Hit() [3/4]

ActsFatras::Hit::Hit ( const Hit & )

default

Copy constructor.

Hit() [4/4]

ActsFatras::Hit::Hit ( Hit && )

default

Move constructor.

Member Function Documentation

depositedEnergy()

double ActsFatras::Hit::depositedEnergy

(

)

const

Energy deposited by the hit.

Return values

positive	if the particle lost energy when it passed the surface
negative	if magic was involved

direction()

Acts::Vector3 ActsFatras::Hit::direction

(

)

const

Average normalized particle direction vector through the surface.

Returns

Average normalized direction vector of particle momentum before and after

directionAfter()

Acts::Vector3 ActsFatras::Hit::directionAfter

(

)

const

Normalized particle direction vector the hit.

Returns

Normalized three-dimensional direction vector after interaction

directionBefore()

Acts::Vector3 ActsFatras::Hit::directionBefore

(

)

const

Normalized particle direction vector before the hit.

Returns

Normalized three-dimensional direction vector before interaction

fourPosition()

const Acts::Vector4 & ActsFatras::Hit::fourPosition

(

)

const

Space-time position four-vector.

Returns

Reference to four-vector containing position and time coordinates

geometryId()

Acts::GeometryIdentifier ActsFatras::Hit::geometryId ( ) const

constexpr

Geometry identifier of the hit surface.

Returns

GeometryIdentifier of the surface where the hit occurred

index()

std::int32_t ActsFatras::Hit::index ( ) const

constexpr

Hit index along the particle trajectory.

Return values

negative

if the hit index is undefined.

momentum4After()

const Acts::Vector4 & ActsFatras::Hit::momentum4After

(

)

const

Particle four-momentum after the hit.

Returns

Reference to four-momentum vector after interaction

momentum4Before()

const Acts::Vector4 & ActsFatras::Hit::momentum4Before

(

)

const

Particle four-momentum before the hit.

Returns

Reference to four-momentum vector before interaction

operator=() [1/2]

Hit & ActsFatras::Hit::operator= ( const Hit & )

default

Copy assignment operator.

Returns

Reference to this hit after copying

operator=() [2/2]

Hit & ActsFatras::Hit::operator= ( Hit && )

default

Move assignment operator.

Returns

Reference to this hit after moving

particleId()

Barcode ActsFatras::Hit::particleId ( ) const

constexpr

Particle identifier of the particle that generated the hit.

Returns

Barcode identifier of the particle that created this hit

position()

auto ActsFatras::Hit::position

(

)

const

Three-position, i.e.

spatial coordinates without the time.

Returns

Three-dimensional position vector (x,y,z)

time()

double ActsFatras::Hit::time

(

)

const

Time coordinate.

Returns

Time of the hit occurrence