# File Interactions.hpp

namespace Acts

Note

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

Functions

float computeEnergyLossBethe(const MaterialSlab &slab, float m, float qOverP, float absQ)

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

• m – Particle mass

• qOverP – Particle charge divided by absolute momentum

• absQ – Absolute particle charge

float computeEnergyLossLandau(const MaterialSlab &slab, float m, float qOverP, float absQ)

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

• m – Particle mass

• qOverP – Particle charge divided by absolute momentum

• absQ – Absolute particle charge

float computeEnergyLossLandauFwhm(const MaterialSlab &slab, float m, float qOverP, float absQ)

Compute the full with half maximum of landau energy loss distribution.

computeEnergyLossBethe for parameters description

float computeEnergyLossLandauSigma(const MaterialSlab &slab, float m, float qOverP, float absQ)

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

This is the sigma parameter 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, float m, float qOverP, float absQ)

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

• m – Particle mass

• qOverP – Particle charge divided by absolute momentum

• absQ – Absolute particle charge

float computeEnergyLossMean(const MaterialSlab &slab, PdgParticle absPdg, float m, float qOverP, float absQ)

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

• absPdg – Absolute particle type PDG identifier

• m – Particle mass

• qOverP – Particle charge divided by absolute momentum

• absQ – Absolute particle charge

float computeEnergyLossMode(const MaterialSlab &slab, PdgParticle absPdg, float m, float qOverP, float absQ)

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

• absPdg – Absolute particle type PDG identifier

• m – Particle mass

• qOverP – Particle charge divided by absolute momentum

• absQ – Absolute particle charge

float computeEnergyLossRadiative(const MaterialSlab &slab, PdgParticle absPdg, float m, float qOverP, float absQ)

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

• absPdg – Absolute particle type PDG identifier

• m – Particle mass

• qOverP – Particle charge divided by absolute momentum

• absQ – Absolute particle charge

float computeMultipleScatteringTheta0(const MaterialSlab &slab, PdgParticle absPdg, float m, float qOverP, float absQ)

Compute the core width of the projected planar scattering distribution.

Parameters
• slab – The traversed material and its properties

• absPdg – Absolute particle type PDG identifier

• m – Particle mass

• qOverP – Particle charge divided by absolute momentum

• absQ – Absolute particle charge

float deriveEnergyLossBetheQOverP(const MaterialSlab &slab, float m, float qOverP, float absQ)

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

• m – Particle mass

• qOverP – Particle charge divided by absolute momentum

• absQ – Absolute particle charge

float deriveEnergyLossLandauQOverP(const MaterialSlab &slab, float m, float qOverP, float absQ)

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

• m – Particle mass

• qOverP – Particle charge divided by absolute momentum

• absQ – Absolute particle charge

float deriveEnergyLossMeanQOverP(const MaterialSlab &slab, PdgParticle absPdg, float m, float qOverP, float absQ)

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

• absPdg – Absolute particle type PDG identifier

• m – Particle mass

• qOverP – Particle charge divided by absolute momentum

• absQ – Absolute particle charge

float deriveEnergyLossModeQOverP(const MaterialSlab &slab, PdgParticle absPdg, float m, float qOverP, float absQ)

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

• absPdg – Absolute particle type PDG identifier

• m – Particle mass

• qOverP – Particle charge divided by absolute momentum

• absQ – Absolute particle charge

float deriveEnergyLossRadiativeQOverP(const MaterialSlab &slab, PdgParticle absPdg, float m, float qOverP, float absQ)

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

• absPdg – Absolute particle type PDG identifier

• m – Particle mass

• qOverP – Particle charge divided by absolute momentum

• absQ – Absolute particle charge