Double-crystal diffractive modulator of synchrotron radiation

Abstract

The efficiency of time-modulation of synchrotron radiation by a double-crystal monochromator periodically curved by pulsed surface acoustic waves has been studied both experimentally and theoretically. It has been shown that the efficiency of such a system is significantly higher as compared to x-ray modulation by surface acoustic waves applied to x-ray mirrors—that is under the conditions of total external reflection. Possible modifications and improvement of a synchrotron radiation double-crystal diffractive modulator are discussed. The experiments were done at the diffraction beamline at the Brazilian National Synchrotron Light Laboratory (LNLS).

Coherent and diffuse X-ray scattering in crystals modulated by a surface acoustic wave

“…To the best of our knowledge, all previously developed theories describing the interaction of X-rays with ultrasound, including X-ray diffraction in the volume of the sample (Kö hler et al, 1974;Entin, 1988) and on its surface (Gabrielyan & Aslanian, 1988;Polikarpov et al, 1998;Schelokov et al, 2004), are restricted to the case of ideal (defect free) crystals. Furthermore, there is still no theory of X-ray diffraction in crystals modulated by a SAW, applicable to a high-resolution triple-crystal diffractometer (Iida & Kohra, 1979;Nesterets & Punegov, 2000).…”

Bulk strains in Si induced by thickness mode ultrasonic waves and analysed with x-ray Bragg diffraction

“…In the case of a strong ultrasonic field it is possible not only to modulate the crystal lattice but also to change the structural phase of materials. The crystal lattice modulation can be used on x-ray optical switches [8][9][10][11][12] and stroboscopic gradient monochromators [13,14]. At each specific depth, by varying the phase of the ultrasonic standing wave, it is possible to select different crystal lattices.…”

“…SAW devices have been used as stroboscopic synchrotron monochromators exploiting relative variations ( d/d) in the lattice parameter (d) close to the surface [9,27].…”

Ultrasound adjustable Laue-Laue double-crystal x-ray monochromator

“…An application of ultrasonic wave (USW) to nearly prefect crystals in combination with x-ray diffraction attracts growing attention due to the possibility, to introduce in a crystal, a periodic deformation variable in a pre-defined reproducible way. This approach is considered promising in application to x-ray diffraction studies of electronic materials [2,3], measurements of weak acoustic fields in acoustooptical devices [4][5][6], construction of synchrotron radiation monochromators [7,8], diffraction modulators [9], quarterwave plates [10] and for control of x-ray beams in time and § Corresponding author.…”