
Figure 12
RMS thermal slope (green line, left axis) error versus absorbed power at Bragg angle _{Bragg} = 16.2° for the LN2cooled silicon crystal for the ESRF UPBL06 beamline project. Different values of the (nonconstant) curvature are plotted (right axis): at the centre of the footprint, the maximum, minimum and average over the central cone illuminated half footprint length. Note that in the absorbed power range (225, 270) W the maximum curvature is positive (concave) whereas the minimum curvature is negative (convex). 