Hadronic Calorimetry
From PGSC Wiki
Recalling that the geometric cross section of a nucleus goes like <math>a_N^2</math> and that the nuclear radius goes like <math>a_N ~ A^{1/3}</math>, one can write the nuclear mean free path as:
<math>\lambda_I ~ [35 g/cm^2]A^{1/3}</math>
<math>\nu = x / \lambda_I</math>