Nuclear transparency

 Nuclear transparency is the ratio of cross-sections for exclusive processes from the nuclei to those of the nucleons.

If a nuclear cross-section is denoted as ${\displaystyle \sigma _{N}}$ and free nucleon cross-section as ${\displaystyle \sigma _{0}}$, then nuclear transparency can be defined as
${\displaystyle T=\sigma _{N}/A\sigma _{0}}$, where ${\displaystyle \sigma _{N}}$ can be parameterized in terms of ${\displaystyle \sigma _{0}}$ as ${\displaystyle \sigma _{N}=A^{\alpha }\sigma _{0}}$.

Therefore, transparency can be expressed as ${\displaystyle T=A^{\alpha -1}}$.
Here, nucleon cross-section can be thought of as a hydrogen cross-section, and nuclei cross-section can be as for other targets.

This article uses material from the Wikipedia article  Metasyntactic variable, which is released under the  Creative Commons Attribution-ShareAlike 3.0 Unported License.