2 Materials

Materials in Radiant are defined by a Radiant.Material object. A material is characterized by an optional human-readable tag, a mass density, a state of matter and a list of elements with their corresponding mass weight fractions.

2.1 Instantiating a Material

A new material is instantiated with the Material constructor, which accepts an optional string tag used to identify the material. This tag must be unique within a calculation if more than one material is defined.

water = Material("water")          # Tagged constructor (recommended)
unnamed = Material()               # Tag can also be set later with set_tag(...)
unnamed.set_tag("aluminum")

2.2 Defining the Composition

Once a material is instantiated, elements are added with add_element. For each element, the chemical symbol and its mass weight fraction (between 0 and 1) are provided. The weight fractions across all the elements of a material must sum to at most 1.

water = Material("water")
water.set_density(1.0)             # Density in g/cm³
water.add_element("H",0.1111)      # Hydrogen with mass weight of 11.11 %
water.add_element("O",0.8889)      # Oxygen with mass weight of 88.89 %

For a monoelemental material, the weight fraction can be omitted; it defaults to 1.0 and the density is automatically set to the tabulated density of that element at 20°C:

al = Material("aluminum")
al.add_element("Al")               # 100 % Al, density set to 2.70 g/cm³

If set_density(...) is called later, it overrides this default value.

2.3 State of Matter

By default a material is "solid". The state of matter influences density-effect corrections in the inelastic-collision cross-sections. The accepted values are "solid", "liquid" and "gaz":

water.set_state_of_matter("liquid")

2.4 Inspecting a Material

Calling println(material) prints a summary of the material:

Material:
   Density (g/cm³):              1.0
   Elements in the compound:     ["h", "o"]
   Weight fractions:             [0.1111, 0.8889]
   State of matter:              liquid

A series of getter methods is also provided to retrieve individual fields:

water.get_tag()                    # "water"
water.get_density()                # 1.0
water.get_state_of_matter()        # "liquid"
water.get_number_of_elements()     # 2
water.get_atomic_numbers()         # [1, 8]
water.get_weight_fractions()       # [0.1111, 0.8889]

2.5 Summary of the Material API