Experimental geometry for energy-dispersive radial diffraction. The ψ is the angle between the diamond cell stress axis and the diffraction plane normal. (a) ψ = 0°, diffraction plane normal parallel to the diamond cell stress axis; (b) ψ = 90°, diffraction plane normal perpendicular to stress axis. (c) Photograph of experimental setup at BSRF, a symmetric DAC is used.