SingleLinearBreitWheelerCollisionEvent.H File Reference

#include "LinearBreitWheelerCrossSection.H"
#include "Particles/Collision/BinaryCollision/BinaryCollisionUtils.H"
#include "Utils/WarpXConst.H"
#include <AMReX_Algorithm.H>
#include <AMReX_Random.H>
#include <AMReX_REAL.H>
#include <cmath>

Go to the source code of this file.

Functions
template<typename index_type>
AMREX_GPU_HOST_DEVICE AMREX_INLINE void	SingleLinearBreitWheelerCollisionEvent (const amrex::ParticleReal &u1x, const amrex::ParticleReal &u1y, const amrex::ParticleReal &u1z, const amrex::ParticleReal &u2x, const amrex::ParticleReal &u2y, const amrex::ParticleReal &u2z, amrex::ParticleReal w1, amrex::ParticleReal w2, const amrex::Real &dt, const amrex::ParticleReal &dV, const int &pair_index, index_type *AMREX_RESTRICT p_mask, amrex::ParticleReal *AMREX_RESTRICT p_pair_reaction_weight, const amrex::ParticleReal &event_multiplier, const int &multiplier_ratio, const amrex::ParticleReal &probability_threshold, const amrex::ParticleReal &probability_target_value, const amrex::RandomEngine &engine)
	This function computes whether the collision between two photons results in a pair-producing (electron and positron) event, using the algorithm described in Higginson et al., Journal of Computational Physics 388, 439-453 (2019). If the electron-positron pair is produced, the mask is set to true for that given pair of macrophotons and the weight of the produced particles is stored in p_pair_reaction_weight.

Function Documentation

SingleLinearBreitWheelerCollisionEvent()

template<typename index_type>

AMREX_GPU_HOST_DEVICE AMREX_INLINE void SingleLinearBreitWheelerCollisionEvent	(	const amrex::ParticleReal &	u1x,
		const amrex::ParticleReal &	u1y,
		const amrex::ParticleReal &	u1z,
		const amrex::ParticleReal &	u2x,
		const amrex::ParticleReal &	u2y,
		const amrex::ParticleReal &	u2z,
		amrex::ParticleReal	w1,
		amrex::ParticleReal	w2,
		const amrex::Real &	dt,
		const amrex::ParticleReal &	dV,
		const int &	pair_index,
		index_type *AMREX_RESTRICT	p_mask,
		amrex::ParticleReal *AMREX_RESTRICT	p_pair_reaction_weight,
		const amrex::ParticleReal &	event_multiplier,
		const int &	multiplier_ratio,
		const amrex::ParticleReal &	probability_threshold,
		const amrex::ParticleReal &	probability_target_value,
		const amrex::RandomEngine &	engine )

This function computes whether the collision between two photons results in a pair-producing (electron and positron) event, using the algorithm described in Higginson et al., Journal of Computational Physics 388, 439-453 (2019). If the electron-positron pair is produced, the mask is set to true for that given pair of macrophotons and the weight of the produced particles is stored in p_pair_reaction_weight.

Note that the word 'pair' sometimes refers to the electron-positron products of the collision, sometimes to the macrophotons that are paired to collide in a cell according to the algorithm. It should be clear from the context.

Template Parameters

index_type

type of the index argument

Parameters

[in]	u1x,u1y,u1z	momentum components of the first colliding particle
[in]	u2x,u2y,u2z	momentum components of the second colliding particle
[in]	w1,w2	effective weight of the colliding particles
[in]	dt	is the time step length between two collision calls.
[in]	dV	is the volume of the corresponding cell.
[in]	pair_index	is the index of the colliding pair
[out]	p_mask	is a mask that will be set to true if pair (electron-positron) production occurs for that pair of macrophotons
[out]	p_pair_reaction_weight	stores the weight of the product particles
[in]	event_multiplier	factor used to increase the number of pair-production events by decreasing the weight of the produced particles
[in]	multiplier_ratio	factor used to take into account unsampled pairs (i.e. the fact that a particle only collides with one or few particles of the other species)
[in]	probability_threshold	probability threshold above which we decrease the event multiplier
[in]	probability_target_value	if the probability threshold is exceeded, this is used to determine by how much the event multiplier is reduced
[in]	engine	the random engine.