Performance of a beam-multiplexing diamond crystal monochromator at the Linac Coherent Light Source

Abstract

A double-crystal diamond monochromator was recently implemented at the Linac Coherent Light Source. It enables splitting pulses generated by the free electron laser in the hard x-ray regime and thus allows the simultaneous operations of two instruments. Both monochromator crystals are High-Pressure High-Temperature grown type-IIa diamond crystal plates with the (111) orientation. The first crystal has a thickness of ∼100 μm to allow high reflectivity within the Bragg bandwidth and good transmission for the other wavelengths for downstream use. The second crystal is about 300 μm thick and makes the exit beam of the monochromator parallel to the incoming beam with an offset of 600 mm. Here we present details on the monochromator design and its performance.

The X-ray Correlation Spectroscopy instrument at the Linac Coherent Light Source

“…) but most importantly allows multiplexing with another instrument located downstream in the FEH (Feng et al, 2013(Feng et al, , 2015Zhu et al, 2014). A detailed discussion concerning the effect of the monochromaticity on the intensity and longitudinal coherence properties of a FEL SASE beam is provided by Lee et al (2012).…”

“…For experiments that require a monochromatic beam [i.e. a larger longitudinal coherence length l = 2 =Á = ðE=ÁEÞ] but do not intend to scan broadly the incident energy, a custom-built (JJ X-ray, Denmark) largeoffset Double-Crystal Monochromator (DCM) (Zhu et al, 2014) is located 44 m upstream of the sample. In this configuration all components located downstream of the dashed line are translated 600 mm horizontally as displayed in Fig.…”

High-accuracy wavefront sensing for x-ray free electron lasers

“…[23]), with the XPP diamond monochromator inserted [24]. The use of the monochromator removes the chromaticity effect of the CRLs, with a tradeoff of reduced overall intensity as well as 100% intensity fluctuations due to the nature of the self-amplified spontaneous emission (SASE) spectrum.…”

Focus characterization at an X-ray free-electron laser by coherent scattering and speckle analysis

“…Pulseto-pulse intensity variations led to large imprint size variations (Lemke et al, 2013b;Zhu et al, 2014). The two single-shot imprints shown were among the smallest obtained on the target.…”