Notes

¹Provided that the gauge dimension along the beam direction is significantly shorter than the attenuation length, the scattered signal is dependent only on the sampling volume V_v, independent of the gauge shape; otherwise the level of scattering is shape dependent. This can be important especially when considering X-rays, in which case V_v can be replaced by V_eff to account for attenuation within the gauge. In the following discussion, it is the sampling volume rather than the shape which is important.