Nuclear transparency

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

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

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