Class Particle¶

Defined in File Particle.hpp

Class Documentation¶

class ActsFatras::Particle¶

Particle identity information and kinematic state.

Also stores some simulation-specific properties.

Public Types

using Scalar = Acts::ActsScalar ¶

using Vector3 = Acts::ActsVector<3>¶

using Vector4 = Acts::ActsVector<4>¶

Public Functions

Particle() = default¶: Construct a default particle with invalid identity.

Particle(Barcode particleId, Acts::PdgParticle pdg, Scalar charge, Scalar mass)¶

Construct a particle at rest with explicit mass and charge.

Warning

It is the users responsibility that charge and mass match the PDG particle number.

Parameters

particleId: Particle identifier within an event
pdg: PDG id
charge: Particle charge in native units
mass: Particle mass in native units

Particle(Barcode particleId, Acts::PdgParticle pdg)¶

Construct a particle at rest from a PDG particle number.

Charge and mass are retrieved from the particle data table.

Parameters

particleId: Particle identifier within an event
pdg: PDG particle number

Particle(const Particle&) = default¶

Particle(Particle&&) = default¶

constexpr Scalar absoluteMomentum() const¶: Absolute momentum.

constexpr Scalar charge() const¶: Particle charge.

Particle &correctEnergy(Scalar delta)¶

Change the energy by the given amount.

Energy loss corresponds to a negative change. If the updated energy would result in an unphysical value, the particle is put to rest, i.e. its absolute momentum is set to zero.

Scalar energy() const¶: Total energy, i.e. norm of the four-momentum.

Vector4 fourMomentum() const¶: Energy-momentum four-vector.

constexpr const Vector4 &fourPosition() const¶: Space-time position four-vector.

constexpr Scalar mass() const¶: Particle mass.

constexpr operator bool() const¶: Check if the particle is alive, i.e. is not at rest.

constexpr bool operator!() const¶: Check if the particle is dead, i.e is at rest.

Particle &operator=(const Particle&) = default¶

Particle &operator=(Particle&&) = default¶

constexpr Barcode particleId() const¶: Particle identifier within an event.

constexpr Scalar pathInL0() const¶: Accumulated path within material measured in interaction lengths.

constexpr Scalar pathInX0() const¶: Accumulated path within material measured in radiation lengths.

constexpr Acts::PdgParticle pdg() const¶: PDG particle number that identifies the type.

auto position() const¶: Three-position, i.e. spatial coordinates without the time.

constexpr ProcessType process() const¶: Which type of process generated this particle.

constexpr Scalar properTime() const¶: Proper time in the particle rest frame.

Particle &setAbsoluteMomentum(Scalar absMomentum)¶: Set the absolute momentum.

Particle &setDirection(const Vector3 &direction)¶: Set the direction three-vector.

Particle &setDirection(Scalar dx, Scalar dy, Scalar dz)¶: Set the direction three-vector from scalar components.

constexpr Particle &setMaterialPassed(Scalar pathInX0, Scalar pathInL0)¶

Set the accumulated material measured in radiation/interaction lengths.

Parameters

pathInX0: accumulated material measured in radiation lengths
pathInL0: accumulated material measured in interaction lengths

Particle &setPosition4(const Vector4 &pos4)¶: Set the space-time position four-vector.

Particle &setPosition4(const Vector3 &position, Scalar time)¶: Set the space-time position four-vector from three-position and time.

Particle &setPosition4(Scalar x, Scalar y, Scalar z, Scalar time)¶: Set the space-time position four-vector from scalar components.

Particle &setProcess(ProcessType proc)¶: Set the process type that generated this particle.

constexpr Particle &setProperTime(Scalar properTime)¶

Set the proper time in the particle rest frame.

Parameters

properTime: passed proper time in the rest frame

Scalar time() const¶: Time coordinate.

Scalar transverseMomentum() const¶: Absolute momentum in the x-y plane.

const Vector3 &unitDirection() const¶: Unit three-direction, i.e. the normalized momentum three-vector.

Particle withParticleId(Barcode particleId) const¶

Construct a new particle with a new identifier but same kinematics.

Note: This is intentionally not a regular setter. The particle id is used to identify the whole particle. Setting it on an existing particle is usually a mistake.