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 2 (transmission definition), Section 5 (experimental corrections)

Structs

InstrumentParams

Optional instrument resolution parameters.

SampleParams

Sample description for the forward model.

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_with_analytical_derivative_from_base

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

forward_model

Compute a complete theoretical transmission spectrum.

forward_model_from_base_xs

Compute a transmission spectrum from precomputed unbroadened cross-sections.

unbroadened_cross_sections

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

Type Aliases

BroadenedXsWithDerivative

Broadened cross-sections and their temperature derivative.