Dancoff's Solution for the Number of Collisions Necessary to Slow Down

A succession of authors, following in the footsteps of Glasstone and Edlund, have perpetuated the same estimate for the number of collisions to slow down. Investigation of the slowing down distribution by Dancoff and others has been shown to correspond to a more meaningful estimate. Dancoff's treatment, probably the most concise of any thus far proposed, is discussed in detail.