Characterization of cryogenically cooled dual symmetric silicon geometry, Si(111)/Si(311), for the double-crystal monochromator on BL11XU at SPring-8

Tozawa, Kazukiyo*; Kiriyama, Koji*; Mitsui, Takaya; Shiwaku, Hideaki   ; Harami, Taikan

Liquid-N-cooled Si crystals replaced water-cooled diamond crystals for the double-crystal monochromator on BL11XU at SPring-8. To use the whole energy from 6keV to 70keV, we adopted the system of alternative dual symmetric Si geometry, Si(111)/Si(311), which can be switched by a horizontal translation (X) stage perpendicular to the beam axis. Before the experiment on BL11XU, the off-line evaluation was performed to estimate the degree of the crystal strain, which may arise from the way of assembling. With MoK, rocking curves from the crystals were measured for the second crystal of the double-crystal diffractometer of parallel setting. Each of the observed FWHM was almost constant and identical to the calculated value wherever X-rays hit on the crystal surface. By the use of synchrotron radiation from the undulator the crystals were tested and then the characterization was performed. The observed intensities and rocking curves resulted in that each crystal was good for BL11XU and that the performance of X-ray reflection was improved.