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 σ N {\displaystyle \sigma _{N}} and free nucleon cross-section as σ 0 {\displaystyle \sigma _{0}} , then nuclear transparency can be defined as
T = σ N / A σ 0 {\displaystyle T=\sigma _{N}/A\sigma _{0}} , where σ N {\displaystyle \sigma _{N}} can be parameterized in terms of σ 0 {\displaystyle \sigma _{0}} as σ N = A α σ 0 {\displaystyle \sigma _{N}=A^{\alpha }\sigma _{0}} . Therefore, transparency can be expressed as T = A α − 1 {\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.
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