Diamond Channel-Cut Crystals for High-Heat-Load, Beam-Multiplexing, Narrow-Band X-ray Monochromators

TL;DR

This paper demonstrates the use of monolithic diamond channel-cut crystals as high-heat-load, beam-multiplexing, narrow-band x-ray monochromators suitable for high-power XFEL facilities, enabling stable, efficient, and versatile x-ray optics.

Contribution

It introduces a novel diamond channel-cut crystal design for high-power, narrow-band x-ray monochromators with minimal absorption and high mechanical stability at XFELs.

Findings

Successfully fabricated and characterized diamond channel-cut crystals.

Achieved high stability with less than 2% absorption of 100-W x-ray beams.

Demonstrated monochromators directing specific x-ray energies with minimal losses.

Abstract

Next-generation, high-brilliance x-ray photon sources call for new x-ray optics. Here we demonstrate the feasibility of using monolithic diamond channel-cut crystals as high-heat-load, beam-multiplexing, narrow-band, mechanically-stable x-ray monochromators with high-power x-ray beams at cutting-edge, high-repetition-rate x-ray free-electron laser (XFEL) facilities. The diamond channel-cut crystals fabricated and characterized in these studies are designed as two-bounce Bragg reflection monochromators directing 14.4-keV or 12.4-keV x-rays within a 15-meV-bandwidth to $^{57}$Fe or $^{45}$Sc nuclear resonant scattering experiments, respectively. The crystal design allows out-of-band x-rays within a $\simeq 1$-eV XFEL bandwidth to be transmitted with minimal losses to alternative simultaneous experiments. Only $\lesssim 2$\% of the incident $\simeq 100$-W x-ray beam is absorbed in a 50-$\mu$m-thick first diamond crystal reflector, ensuring that the monochromator crystal is highly stable. Other x-ray optics applications of diamond channel-cut crystals are anticipated.