Performance analysis of cryogenic silicon Laue monochromators at APS undulators

摘要

We investigated the performance of a cryogenically cooled silicon monochromator crystal exposed to high power x-ray undulator radiation. The heat transfer in this nonlinear material was studied analytically by approximating the thermal conductivity and then scaling relations for the temperature distributions with the cooling temperature and the power load were found. The strain distributions in this nonlinear material were studied analytically by approximating the thermal expansion coefficient. The broadening of the rocking curve was found to be determined, to the first order, by the maximum temperature and a load factor $gamma which is determined by the properties of the source and the crystal, and independent of the optical geometry. Major conclusions were verified through numerical analysis with the program ANSYS. We concluded that cryogenically cooled silicon Laue monochromator should work with Undulator A at the Advanced Photon Source.