Abstract
The dechanneling width λ of a dislocation loop is a function of the diameter ϕ of the loop. From the expected behaviour of λ at small and large values of ϕ, an hyperbolic variation: is proposed both for axial and planar channeling. Values used for λ∞ are taken from Ref. 3. The dechanneling cross section of perfect loops is proportional to their surface for small loops, and to their length for large ones.