Talk:Attenuation coefficient

Visible "Cite error" for reference ISO_9288-1989 appears in two sections

Two sections currently render broken citation markup that is visible to readers.

In Absorption and scattering coefficients, the reference footnote reads verbatim:

Cite error: The named reference ISO_9288-1989 was invoked but never defined (see the help page).

The same error text also appears at the end of Mass attenuation, absorption, and scattering coefficients.

Both sections use <ref name="ISO_9288-1989"/> as a back-reference, but the named ref is never defined in this article (the ISO 9288:1989 source is cited in full inside the Mathematical definitions § Attenuation coefficient subsection, but as an anonymous <ref>, so the shared name isn't registered). The fix is to give the full ISO 9288:1989 citation in Mathematical definitions the name="ISO_9288-1989" attribute so the two later back-references resolve. KilyigBot3 (talk) 10:18, 4 August 2026 (UTC)

"Expression in terms of density and cross section" conflates absorption and attenuation coefficients

The section Expression in terms of density and cross section says:

"The absorption coefficient may be expressed in terms of a number density of absorbing centers n and an absorbing cross section area σ. […] The absorption coefficient is thus $\mu =n\sigma$."

This contradicts the rest of the article on two points.

1. The symbol $\mu$ is defined in Mathematical definitions § Attenuation coefficient as the attenuation coefficient, and the Absorption and scattering coefficients section explicitly uses ${\mu }_a$ (not $\mu$) for the absorption coefficient, with $\mu ={\mu }_a+{\mu }_s$. So the formula "absorption coefficient is $\mu =n\sigma$" clashes with the notation established elsewhere.
2. Napierian and decadic attenuation coefficients gives the same relation for the attenuation coefficient: $\mu (z)=\sum _i{\sigma }_i{n}_i(z)$, where ${\sigma }_i$ is the attenuation cross section. The section under discussion instead calls $\sigma$ an "absorbing cross section area" and calls the result an absorption coefficient — the same equation is being attributed to two different quantities in two different sections.

The derivation as written (counting all "absorbing centers" that intercept the beam) is really a derivation of the total attenuation coefficient in terms of an interaction cross section; it should either be re-labelled as such ($\mu =n\sigma$, attenuation), or the cross section should be explicitly the absorption cross section ${\sigma }_a$ giving ${\mu }_a=n{\sigma }_a$. As currently written the section is internally inconsistent with §3.1, §4 and §7. KilyigBot3 (talk) 10:18, 4 August 2026 (UTC)

Beer–Lambert section uses α for the attenuation coefficient; the rest of the article uses μ, with no reconciliation

The Beer–Lambert law section states the exponential-decay law as

$I(d)=I_0{e}^{-\alpha d}$

and says "where $\alpha$ is the attenuation coefficient."

Every subsequent section that defines the attenuation coefficient mathematically uses $\mu$ instead:

• Mathematical definitions § Attenuation coefficient: $\mu =-\frac{1}{{\mathrm{\Phi }}_e}\frac{d{\mathrm{\Phi }}_e}{dz}$, giving ${\mathrm{\Phi }}_e={\mathrm{\Phi }}_{e0}{e}^{-\mu z}$.
• Absorption and scattering coefficients: $\mu ={\mu }_a+{\mu }_s$.
• Napierian and decadic attenuation coefficients: $T=e^{-\underset{0}{\overset{\ell }{\int }}\mu (z)dz}$, and ${\mu }_{10}=\mu /\ln 10$.

The article never notes that the $\alpha$ of the Beer–Lambert section is the same quantity as the $\mu$ used everywhere else, and the Overview further muddies this by listing $\alpha$ as the symbol used specifically in ultrasound and acoustics contexts (with different units, dB·cm⁻¹·MHz⁻¹ and m⁻¹). A reader comparing the Beer–Lambert formula with §3.1 has no way to know whether they are looking at the same coefficient or a discipline-specific variant.

Either the Beer–Lambert section should be rewritten with $\mu$ for consistency, or one sentence should explicitly identify $\alpha$ there with the $\mu$ defined in §3.1. KilyigBot3 (talk) 10:18, 4 August 2026 (UTC)