# File Interactions.hpp¶

namespace Acts

Note

This file is foreseen for the `Geometry` module to replace `Extent`

Functions

float computeEnergyLossBethe(const MaterialSlab &slab, int pdg, float m, float qOverP, float q = UnitConstants::e)

Compute the mean energy loss due to ionisation and excitation.

This computes the mean energy loss -dE(x) through a material with the given properties, i.e. it computes

```-dE(x) = -dE/dx * x
```

where -dE/dx is given by the Bethe formula. The computations are valid for intermediate particle energies.

Parameters
• slab – The traversed material and its properties

• pdg – Particle type PDG identifier

• m – Particle mass

• qOverP – Particle charge divided by absolute momentum

• q – Particle charge, only the magnitude is considered

float computeEnergyLossLandau(const MaterialSlab &slab, int pdg, float m, float qOverP, float q = UnitConstants::e)

Compute the most propable energy loss due to ionisation and excitation.

Compute the mean energy loss due to ionisation and excitation.

This computes the mean energy loss -dE(x) through a material with the given properties, i.e. it computes

```-dE(x) = -dE/dx * x
```

where -dE/dx is given by the Bethe formula. The computations are valid for intermediate particle energies.

This computes the most probable energy loss -dE(x) through a material of the given properties and thickness as described by the mode of the Landau-Vavilov-Bichsel distribution. The computations are valid for intermediate particle energies.

Parameters
• slab – The traversed material and its properties

• pdg – Particle type PDG identifier

• m – Particle mass

• qOverP – Particle charge divided by absolute momentum

• q – Particle charge, only the magnitude is considered

float computeEnergyLossLandauSigma(const MaterialSlab &slab, int pdg, float m, float qOverP, float q = UnitConstants::e)

Compute the Gaussian-equivalent sigma for the ionisation loss fluctuations.

This is the sigma paramter of a Gaussian distribution with the same full-width-half-maximum as the Landau-Vavilov-Bichsel distribution. The computations are valid for intermediate particle energies.

computeEnergyLossBethe for parameters description

float computeEnergyLossLandauSigmaQOverP(const MaterialSlab &slab, int pdg, float m, float qOverP, float q = UnitConstants::e)

Compute q/p Gaussian-equivalent sigma due to ionisation loss fluctuations.

Compute the mean energy loss due to ionisation and excitation.

This computes the mean energy loss -dE(x) through a material with the given properties, i.e. it computes

```-dE(x) = -dE/dx * x
```

where -dE/dx is given by the Bethe formula. The computations are valid for intermediate particle energies.

Parameters
• slab – The traversed material and its properties

• pdg – Particle type PDG identifier

• m – Particle mass

• qOverP – Particle charge divided by absolute momentum

• q – Particle charge, only the magnitude is considered

float computeEnergyLossMean(const MaterialSlab &slab, int pdg, float m, float qOverP, float q = UnitConstants::e)

Compute the combined mean energy loss.

This computes the combined mean energy loss -dE(x) including ionisation and radiative effects. The computations are valid over a wide range of particle energies.

Parameters
• slab – The traversed material and its properties

• pdg – Particle type PDG identifier

• m – Particle mass

• qOverP – Particle charge divided by absolute momentum

• q – Particle charge, only the magnitude is considered

float computeEnergyLossMode(const MaterialSlab &slab, int pdg, float m, float qOverP, float q = UnitConstants::e)

Compute the combined most probably energy loss.

Compute the combined mean energy loss.

This computes the combined mean energy loss -dE(x) including ionisation and radiative effects. The computations are valid over a wide range of particle energies.

Parameters
• slab – The traversed material and its properties

• pdg – Particle type PDG identifier

• m – Particle mass

• qOverP – Particle charge divided by absolute momentum

• q – Particle charge, only the magnitude is considered

float computeEnergyLossRadiative(const MaterialSlab &slab, int pdg, float m, float qOverP, float q = UnitConstants::e)

Compute the mean energy loss due to radiative effects at high energies.

This computes the mean energy loss -dE(x) using an approximative formula. Bremsstrahlung is always included; direct e+e- pair production and photo-nuclear interactions only for muons.

Parameters
• slab – The traversed material and its properties

• pdg – Particle type PDG identifier

• m – Particle mass

• qOverP – Particle charge divided by absolute momentum

• q – Particle charge, only the magnitude is considered

float computeMultipleScatteringTheta0(const MaterialSlab &slab, int pdg, float m, float qOverP, float q = UnitConstants::e)

Compute the core width of the projected planar scattering distribution.

Parameters
• slab – The traversed material and its properties

• pdg – Particle type PDG identifier

• m – Particle mass

• qOverP – Particle charge divided by absolute momentum

• q – Particle charge, only the magnitude is considered

float deriveEnergyLossBetheQOverP(const MaterialSlab &slab, int pdg, float m, float qOverP, float q = UnitConstants::e)

Derivative of the Bethe energy loss with respect to q/p.

Compute the mean energy loss due to ionisation and excitation.

This computes the mean energy loss -dE(x) through a material with the given properties, i.e. it computes

```-dE(x) = -dE/dx * x
```

where -dE/dx is given by the Bethe formula. The computations are valid for intermediate particle energies.

Parameters
• slab – The traversed material and its properties

• pdg – Particle type PDG identifier

• m – Particle mass

• qOverP – Particle charge divided by absolute momentum

• q – Particle charge, only the magnitude is considered

float deriveEnergyLossLandauQOverP(const MaterialSlab &slab, int pdg, float m, float qOverP, float q = UnitConstants::e)

Derivative of the most probable ionisation energy loss with respect to q/p.

Compute the mean energy loss due to ionisation and excitation.

This computes the mean energy loss -dE(x) through a material with the given properties, i.e. it computes

```-dE(x) = -dE/dx * x
```

where -dE/dx is given by the Bethe formula. The computations are valid for intermediate particle energies.

Parameters
• slab – The traversed material and its properties

• pdg – Particle type PDG identifier

• m – Particle mass

• qOverP – Particle charge divided by absolute momentum

• q – Particle charge, only the magnitude is considered

float deriveEnergyLossMeanQOverP(const MaterialSlab &slab, int pdg, float m, float qOverP, float q = UnitConstants::e)

Derivative of the combined mean energy loss with respect to q/p.

Compute the combined mean energy loss.

This computes the combined mean energy loss -dE(x) including ionisation and radiative effects. The computations are valid over a wide range of particle energies.

Parameters
• slab – The traversed material and its properties

• pdg – Particle type PDG identifier

• m – Particle mass

• qOverP – Particle charge divided by absolute momentum

• q – Particle charge, only the magnitude is considered

float deriveEnergyLossModeQOverP(const MaterialSlab &slab, int pdg, float m, float qOverP, float q = UnitConstants::e)

Derivative of the combined most probable energy loss with respect to q/p.

Compute the combined mean energy loss.

This computes the combined mean energy loss -dE(x) including ionisation and radiative effects. The computations are valid over a wide range of particle energies.

Parameters
• slab – The traversed material and its properties

• pdg – Particle type PDG identifier

• m – Particle mass

• qOverP – Particle charge divided by absolute momentum

• q – Particle charge, only the magnitude is considered

float deriveEnergyLossRadiativeQOverP(const MaterialSlab &slab, int pdg, float m, float qOverP, float q = UnitConstants::e)

Derivative of the mean radiative energy loss with respect to q/p.

Compute the mean energy loss due to radiative effects at high energies.

This computes the mean energy loss -dE(x) using an approximative formula. Bremsstrahlung is always included; direct e+e- pair production and photo-nuclear interactions only for muons.

Parameters
• slab – The traversed material and its properties

• pdg – Particle type PDG identifier

• m – Particle mass

• qOverP – Particle charge divided by absolute momentum

• q – Particle charge, only the magnitude is considered