3 Particles

In Radiant, particles are represented by the Radiant.Particle object. There are two primary ways to instantiate such an object:

Using Reserved Particle Constructors: Reserved constructors are designed for predefined particles with known mass and charge. Each of these generates a Radiant.Particle object preloaded with the physical properties specific to that particle type.

photon     = Photon()
electron   = Electron()
positron   = Positron()
proton     = Proton()
antiproton = Antiproton()
alpha      = Alpha()
muon       = Muon()
antimuon   = Antimuon()

Optionally, a string tag can be provided to the constructor:

e_beam = Electron("primary_electron")

Setting an explicit tag is recommended when several Particle objects of the same kind are used in a single calculation, since the tag is used to distinguish them.

Using the General Constructor: The general constructor allows the creation of user-defined particles. The tag is mandatory; the mass (in MeV) and the charge are optional.

heavy_ion = Particle("heavy_ion",1.0e3,2.0)   # tag, mass [MeV], charge

The default reserved particles use the following properties:

3.1 Inspecting a Particle

Getter methods give access to a particle's properties and can be used to test its type:

get_tag(electron)         # "electron"
get_mass(electron)        # 0.51099895069
get_charge(electron)      # -1
get_type(electron)        # Electron (abstract type)

is_photon(electron)       # false
is_electron(electron)     # true
is_positron(electron)     # false
# Similarly: is_proton, is_antiproton, is_alpha, is_muon, is_antimuon

The tag of a particle can be reassigned at any time using set_tag(particle,new_tag).

3.2 Reserved vs Custom Particles

The reserved particle types (Photon, Electron, Positron, ...) can only be instantiated through their dedicated constructors. This guarantees that interactions and cross-section models (e.g. Compton scattering for photons, Møller for electrons) recognize the particle and apply the appropriate physics. Particles created with the general Particle(tag, ...) constructor have type Custom_Particle and cannot trigger the built-in physics models.

3.3 Summary of the Particle API