impact parameter, \(b\)

https://doi.org/10.1351/goldbook.I02987
In simple hard sphere @C01170@ the distance of closest approach that would result for two particles in a collision if the particle trajectories were undeflected by the collision.
Sources:
Green Book, 2nd ed., p. 56 [Terms] [Book]
PAC, 1991, 63, 1541. (Recommendations for nomenclature and symbolism for mass spectroscopy (including an appendix of terms used in vacuum technology). (Recommendations 1991)) on page 1555 [Terms] [Paper]
PAC, 1996, 68, 149. (A glossary of terms used in chemical kinetics, including reaction dynamics (IUPAC Recommendations 1996)) on page 168 [Terms] [Paper]