Function beer_lambert 

pub fn beer_lambert(cross_sections: &[f64], thickness: f64) -> Vec<f64>

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

T(E) = exp(-thickness × σ(E))

Arguments

• cross_sections — Total cross-sections in barns at each energy point.
• thickness — Areal density in atoms/barn (= number_density × path_length).

Returns

Transmission values (0 to 1) at each energy point.