Inexpensive, Minimally Invasive Fluorescent Imaging of the X-Ray Beam with Simultaneous Flux Measurement

X-ray beamlines at user facilities dynamically change their beam parameters – flux, size, shape and x-ray energy – to meet user needs, often through the use of dynamic focusing elements such as toroidal mirrors. In such cases, the beam optimization procedure is often time consuming and complex, requiring several iterations before the desired beam parameters are obtained. There is a need for beam monitoring devices with fast feedback, calibrated flux response and wide dynamic range, which are capable of imaging the x-ray beam in real time for efficient beam optimization. Specifically, beam profile and flux monitors that absorb less than 10% of the beam energy are needed for online diagnostics. Euclid Techlabs proposes to use commercially available diamond scintillator screens with a standard thickness of 50 microns to record beam fluorescence with camera. Modern scientific cameras with 95% quantum efficiencies achieve an impressive 90 dB dynamic range. This covers reduced signal from ultrathin scintillators. For flux monitoring we propose a more sensitive measurement that is based on a change of the microwave coupling to a high-quality-factor resonator due to x-ray induced conductivity in a scintillator screen. Such measurements were demonstrated recently by Euclid at the Cornell High Energy Synchrotron Source. In Phase I, we will produce a proof-of-principle prototype: a microwave resonator with a fluorescent diamond film inside. The diamond film will be cut to a thickness of 20–50 microns to minimally intercept x-rays. We will measure fluorescence with camera on sample diamond films of various thicknesses to estimate the sensitivity requirements for beam profile measurement. Schedule permitting, we will perform flux measurement with a resonator. The proposed approach is plug and play and can be employed in a large number of x-ray beamlines all over the world. This non-contact flux measurement can potentially eliminate dedicated x-ray flux monitors, which occupy space and block the beam. Beam profile measurement provides an additional functionality for positional feedback. This technology will increase the efficiency of x-ray utilization, simplify sample management, and help with beam delivery and alignment.