Improvement in Stability of SPring‐8 Standard X‐Ray Monochromators with Water‐Cooled Crystals

SPring‐8 standard double‐crystal monochromators containing water‐cooled crystals were stabilized to a sufficient level to function as a part of optics components to supply stable microfocused x‐ray beams, by determining causes of the instability and then removing them. The instability was caused by two factors—thermal deformation of fine stepper stages in the monochromator, which resulted in reduction in beam intensity with time, and vibrations of coolant supply units and vacuum pumps, which resulted in fluctuation in beam intensity. We remodeled the crystal holders to maintain the stage temperatures constant with water, attached x‐ray and electron shields to the stages in order to prevent their warming up, introduced accumulators in the water circuits to absorb pressure pulsation, used polyurethane tubes to stabilize water flow, and placed rubber cushions un der scroll vacuum pumps. As a result, the intensity reduction rate of the beam decreased from 26% to 1% per hour and the intensity fluctuation from ...