Module transmission 

Transmission forward model via the Beer-Lambert law.

Computes theoretical neutron transmission spectra from resonance parameters, applying cross-section calculation, Doppler broadening, resolution broadening, and the Beer-Lambert attenuation law.

Beer-Lambert Law

For a single isotope: T(E) = exp(-n·d·σ(E))

For multiple isotopes: T(E) = exp(-Σᵢ nᵢ·dᵢ·σᵢ(E))

where n is number density (atoms/cm³), d is thickness (cm), and σ(E) is the total cross-section in barns (1 barn = 10⁻²⁴ cm²).

In practice, the product n·d is expressed as “areal density” in atoms/barn, so T(E) = exp(-thickness × σ(E)) with thickness in atoms/barn.

SAMMY Reference

• cro/ and xxx/ modules — cross-section to transmission conversion
• Manual Section II (cross-section theory); transmission experiments Section III.E.1

Structs

InstrumentParams

Optional instrument resolution parameters.

SampleParams

Sample description for the forward model.

WorkingGridLayout

The working energy grid used for broadening, plus the map back to the data grid.

WorkingGridXs

Working-grid Doppler-broadened cross-sections plus the data-grid map.

WorkingGridXsWithDerivative

Working-grid Doppler-broadened cross-sections and their analytical temperature derivative, plus the data-grid map.

Enums

SampleParamsError

Errors from SampleParams construction.

TransmissionError

Errors from the transmission forward model.

Functions

beer_lambert

Compute transmission from cross-sections via Beer-Lambert law.

beer_lambert_multi

Compute transmission for multiple isotopes.

broadened_cross_sections

Compute Doppler-broadened cross-sections for each isotope.

broadened_cross_sections_for_transmission

Compute Doppler+resolution-broadened cross-sections using SAMMY’s Beer-Lambert-aware pipeline for transmission data.

broadened_cross_sections_from_base

Compute Doppler-broadened cross-sections from precomputed unbroadened cross-sections.

broadened_cross_sections_from_base_on_working_grid

Like broadened_cross_sections_from_base but returns the Doppler-broadened σ on the working grid (auxiliary extended grid when Gaussian resolution is active, else the data grid) together with the WorkingGridLayout.

broadened_cross_sections_on_working_grid

Like broadened_cross_sections but returns the Doppler-broadened σ on the working grid (auxiliary extended grid when Gaussian resolution is active, else the data grid) together with the WorkingGridLayout.

broadened_cross_sections_with_analytical_derivative_from_base

Compute Doppler-broadened cross-sections and their analytical temperature derivative from precomputed unbroadened cross-sections.

broadened_cross_sections_with_analytical_derivative_from_base_on_working_grid

Like broadened_cross_sections_with_analytical_derivative_from_base but returns σ and ∂σ/∂T on the working grid (auxiliary extended grid when Gaussian resolution is active, else the data grid) together with the WorkingGridLayout.

forward_model

Compute a complete theoretical transmission spectrum.

forward_model_from_base_xs

Compute a transmission spectrum from precomputed unbroadened cross-sections.

resolution_working_grid

Compute the working-grid layout for (energies, instrument, resonance_data).

resonance_center_energies

Distinct resonance center energies (eV) across every isotope and formalism, sorted ascending.

unbroadened_cross_sections

Compute unbroadened (raw Reich-Moore) cross-sections for each isotope.

Type Aliases

BroadenedXsWithDerivative

Broadened cross-sections and their temperature derivative.