# Propagation Modules¶

group Propagation

Modules that propagate a Candidate.

class DiffusionSDE : public Module
#include <DiffusionSDE.h>

Propagates candidates as pseudo(!)-particles. The time integration of SDEs is used to solve the transport equation. Here an Euler-Mayurama integration scheme is used. The diffusion tensor can be anisotropic with respect to the magnetic field line coordinates. The integration of field lines is done via the CK-algorithm.

class PropagationBP : public Module
#include <PropagationBP.h>

Propagation through magnetic fields using the Boris method.

This module solves the equations of motion of a relativistic charged particle when propagating through a magnetic field.

It uses the Boris push integration method.

It can be used with a fixed step size or an adaptive version which supports the step size control. The step size control tries to keep the relative error close to, but smaller than the designated tolerance. Additionally a minimum and maximum size for the steps can be set. For neutral particles a rectilinear propagation is applied and a next step of the maximum step size proposed.

class PropagationCK : public Module
#include <PropagationCK.h>

Rectilinear propagation through magnetic fields using the Cash-Karp method.

This module solves the equations of motion of a relativistic charged particle when propagating through a magnetic field.

It uses the Runge-Kutta integration method with Cash-Karp coefficients.

The step size control tries to keep the relative error close to, but smaller than the designated tolerance. Additionally a minimum and maximum size for the steps can be set. For neutral particles a rectilinear propagation is applied and a next step of the maximum step size proposed.

class SimplePropagation : public Module
#include <SimplePropagation.h>

Simple rectilinear propagation in absence of magnetic fields.

This module implements rectilinear propagation. The step size is guaranteed to be larger than minStep and smaller than maxStep. It always proposes a next step size of maxStep.