Performance prediction of cryogenically cooled silicon crystal monochromator

To predict the performance of the cryogenically cooled silicon crystal, intensive studies have been carried out to sort out the influences of various parameters, such as heat load power and power distribution, cooling coefficient, and beam size. The thermal slope error of the crystal is calculated by finite element modeling. Quadratic law was applied to calculate the rocking-curve width. Heat load tests were also performed with a channel-cut silicon monochromator on beamline ID09 at the European Synchrotron Radiation Facility (ESRF). The silicon crystal is indirectly cooled from the sides by liquid nitrogen. Measured rocking-curve widths are compared with those calculated by finite element modeling. When we include the broadening from the intrinsic rocking-curve width and mounting strain, the calculated rocking-curve width versus heat load is in excellent agreement with experiment.