File NuclearInteraction.hpp¶

namespace ActsFatras

struct NuclearInteraction¶

#include <ActsFatras/Physics/NuclearInteraction/NuclearInteraction.hpp>

This class provides a parametrised nuclear interaction.

The thereby required parametrisation needs to be set and is not provided by default.

Note

This class differs between two different processes labelled as nuclear interaction. Either the initial particle survives (soft) or it gets destroyed (hard) by this process.

Public Types

using Scalar = Particle::Scalar ¶

Public Functions

template<typename generator_t> inline std::pair<Scalar, Scalar> generatePathLimits(generator_t &generator, const Particle &particle) const¶

This method evaluates the nuclear interaction length L0.

Template Parameters

generator_t – The random number generator type

Parameters

generator – [inout] The random number generator
particle – [in] The ingoing particle

Returns

valid X0 limit and no limit on L0

template<typename generator_t> inline bool run(generator_t &generator, Particle &particle, std::vector<Particle> &generated) const¶

This method performs a nuclear interaction.

Template Parameters

generator_t – The random number generator type

Parameters

generator – [inout] The random number generator
particle – [inout] The ingoing particle
generated – [out] Additional generated particles

Returns

True if the particle was killed, false otherwise

Public Members

detail::MultiParticleNuclearInteractionParametrisation multiParticleParameterisation¶: The storage of the parameterisation.

unsigned int nMatchingTrials = 100¶: The number of trials to match momenta and inveriant masses.

unsigned int nMatchingTrialsTotal = 1000¶

Private Functions

template<typename generator_t> std::vector<Particle> convertParametersToParticles(generator_t &generator, const std::vector<int> &pdgId, const Acts::ActsDynamicVector &momenta, const Acts::ActsDynamicVector &invariantMasses, Particle &initialParticle, float parametrizedMomentum, bool soft) const¶

Converter from sampled numbers to a vector of particles.

Template Parameters

generator_t – The random number generator type

Parameters

generator – [inout] The random number generator
pdgId – [in] The PDG IDs
momenta – [in] The momenta
invariantMasses – [in] The invariant masses
initialParticle – [in] The initial particle
parametrizedMomentum – [in] Momentum of the parametrisation
soft – [in] Treat it as soft or hard nuclear interaction

Returns

Vector containing the final state particles

unsigned int finalStateMultiplicity(double rnd, const detail::NuclearInteractionParameters::CumulativeDistribution &distribution) const¶

Evaluates the multiplicity of the final state.

Parameters

rnd – [in] Random number
distribution – [in] The multiplicity distribution

Returns

The final state multiplicity

const detail::NuclearInteractionParameters &findParameters(double rnd, const detail::NuclearInteractionParametrisation &parametrisation, float particleMomentum) const¶

Retrieves the parametrisation for the particle.

Parameters

rnd – [in] A random number
parametrisation – [in] The storage of parametrisations
particleMomentum – [in] The particles momentum

Returns

The parametrisation

std::pair<ActsFatras::Particle::Scalar, ActsFatras::Particle::Scalar> globalAngle(ActsFatras::Particle::Scalar phi1, ActsFatras::Particle::Scalar theta1, float phi2, float theta2) const¶

Converts relative angles to absolute angles wrt the global coordinate system.

Note

It is assumed that the angles of the first particle are provided in the context of the global coordinate system whereas the angles of the second particle are provided relatively to the first particle.

Parameters

phi1 – [in] The azimuthal angle of the first particle
theta1 – [in] The polar angle of the first particle
phi2 – [in] The azimuthal angle of the second particle
theta2 – [in] The polar angle of the second particle

Returns

Azimuthal and polar angle of the second particle in the global coordinate system

bool match(const Acts::ActsDynamicVector &momenta, const Acts::ActsDynamicVector &invariantMasses, float parametrizedMomentum) const¶

Tests whether the final state momenta and invariant masses are matching to each other to allow the evaluation of particle directions.

Parameters

momenta – [in] The final state momenta
invariantMasses – [in] The final state invariant masses
parametrizedMomentum – [in] The momentum of the parametrized particle

Returns

Decision whether the parameters can be matched to each other or not.

Scalar sampleContinuousValues(double rnd, const detail::NuclearInteractionParameters::CumulativeDistribution &distribution, bool interpolate = false) const¶

This function performs an inverse sampling to provide a continuous value from a distribition.

Parameters

rnd – [in] A random number in [0,1]
distribution – [in] The distribution to sample from
interpolate – [in] Flag to steer whether an interpolation between neighbouring bins should be performed instead of a bin lookup

Returns

The sampled value

unsigned int sampleDiscreteValues(double rnd, const detail::NuclearInteractionParameters::CumulativeDistribution &distribution) const¶

This function performs an inverse sampling to provide a discrete value from a distribution.

Parameters

rnd – [in] A random number in [0,1]
distribution – [in] The distribution to sample from

Returns

The sampled value

template<typename generator_t> Acts::ActsDynamicVector sampleInvariantMasses(generator_t &generator, const detail::NuclearInteractionParameters::ParametersWithFixedMultiplicity &parametrisation) const¶

Evaluates the final state invariant masses.

Template Parameters

generator_t – The random number generator type

Parameters

generator – [inout] The random number generator
parametrisation – [in] Parametrisation of kinematic properties

Returns

Vector containing the invariant masses

template<typename generator_t> std::optional<std::pair<Acts::ActsDynamicVector, Acts::ActsDynamicVector>> sampleKinematics(generator_t &generator, const detail::NuclearInteractionParameters::ParametersWithFixedMultiplicity &parameters, float momentum) const¶

This method samples the kinematics of the final state particles.

Template Parameters

generator_t – The random number generator type

Parameters

generator – [inout] The random number generator
parameters – [in] The parametrisation
momentum – [in] The momentum of the parametrisation

Returns

The final state momenta and invariant masses

template<typename generator_t> Acts::ActsDynamicVector sampleMomenta(generator_t &generator, const detail::NuclearInteractionParameters::ParametersWithFixedMultiplicity &parametrisation, float initialMomentum) const¶

Evaluates the final state momenta.

Template Parameters

generator_t – The random number generator type

Parameters

generator – [inout] The random number generator
parametrisation – [in] Parametrisation of kinematic properties
initialMomentum – [in] The initial momentum

Returns

Vector containing the momenta

template<typename generator_t> std::vector<int> samplePdgIds(generator_t &generator, const detail::NuclearInteractionParameters::PdgMap &pdgMap, unsigned int multiplicity, int particlePdg, bool soft) const¶

Evaluates the final state PDG IDs.

Template Parameters

generator_t – The random number generator type

Parameters

generator – [inout] The random number generator
pdgMap – [in] The branching probability map
multiplicity – [in] The final state multiplicity
particlePdg – [in] The PDG ID of the initial particle
soft – [in] Treat it as soft or hard nuclear interaction

Returns

Vector containing the PDG IDs

inline bool softInteraction(double rnd, float probability) const¶

Estimates the interaction type.

Parameters

rnd – [in] Random number
probability – [in] The probability for a soft interaction

Returns

True if a soft interaction occurs