Numerical values of collision lengths neutrons

Values of bcoh,bcoh2 and rinc are listed below (see Table 6.2), for nuclei usually found in polymers. The unity of area is the barn (1 barn = 10 24 cm2). We note that the incoherent scattering cross-section is relatively very large. This is the main origin of the experimental random noise . 

Let us also recall (see Section 4.4.1.2) that the coherent collision length associated with a proton belonging to a target made up of polarized protons is 

4 Simple scattering of light by an assembly of polarizable elements 

A propagating electric field °E(r, t) acts on an assembly of polarizable elements, bound to an orthogonal reference system OX, O Y, OZ. Let us calculate the value of the scattered field at a point of position vector r. To express the components of this field, we shall use the orthogonal system Ox(r), Ov(r), Oz(r) where Oz(f) has the same direction as r and where Ox(r) coincides with Ox (see Fig. 6.1). We shall study the scattering in the plane OF, OZ. For a target 

For a set of N elements, with position vectors rj(j = 1,. . ., TV), and, in the simple collision approximation, the scattered field is given by the sum 

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