Class Acts::ElementFraction

class ElementFraction

Memory-efficient storage of the relative fraction of an element.

This can be used to define materials that are compounds of multiple elements with varying fractions. The element is identified by its atomic number stored as a single byte (allows up to 256 elements; more than we need). Its fraction is also stored as a single byte with values between 0 and

  1. This gives an accuracy of 1/256 ~ 0.5 %.

The element fraction allows you to store element composition in merged materials with a large number of bins. Depending on the detector and the description granularity this can be a lot of information and thus requires the reduced memory footprint. This is really only needed for nuclear interaction in the fast simulation where the reduced fractional accuracy is not a problem. The fractional accuracy should be much better than the parametrization uncertainty for hadronic interactions.

Public Functions

ElementFraction() = delete

Must always be created with valid data.

ElementFraction(const ElementFraction&) = default
ElementFraction(ElementFraction&&) = default
inline constexpr ElementFraction(unsigned int e, float f)

Construct from atomic number and relative fraction.

  • e – is the atomic number of the element

  • f – is the relative fraction and must be a value in [0,1]

inline explicit constexpr ElementFraction(unsigned int e, unsigned int w)

Construct from atomic number and integer weight.

  • e – is the atomic number of the element

  • w – is the integer weight and must be a value in [0,256)

~ElementFraction() = default
inline constexpr uint8_t element() const

The element atomic number.

inline constexpr float fraction() const

The relative fraction of this element.

ElementFraction &operator=(const ElementFraction&) = default
ElementFraction &operator=(ElementFraction&&) = default