Absorption Corrections for a Four-Quadrant SuperX EDS Detector

Consider a four-quadrant detector consisting of four circular active regions of area Aq each, placed symmetrically around the sample, as shown schematically in Fig. 1(a). The sample holder is inserted from the right, and the quadrants are 90° apart, oriented symmetrically at ±45° with respect to the primary tilt axis. The specimen tilt angles are labeled  and β, with positive angles corresponding to counterclockwise rotations. Each detector quadrant is located above the plane of the specimen and is tilted from the vertical plane by an angle d; the angle between the line connecting the center of a quadrant D with the eucentric point S and the horizontal plane is labeled d (Fig. 1(b)). The active circular regions have a radius of Rd, and a distance to the eucentric point of rd; the detector opening angle is R = Rd/rd. When R is not negligible, as is the case for a SuperX detector, then the x-ray photon path length inside the sample becomes a function of the position on the detector where the pho-ton hits; the absorption correction factor must thus involve an integration over the detector surface area.