Date of Award

12-2024

Degree Name

Doctor of Philosophy

Department

Physics

First Advisor

Clement Burns, Ph.D.

Second Advisor

Lisa Paulius, Ph.D.

Third Advisor

Zbigniew Chajecki, Ph.D.

Fourth Advisor

Yuri Shvyd’ko, Ph.D.

Abstract

The Cavity-Based X-ray Free Electron Laser (CBXFEL) is a possible future direction in the development of fully coherent hard X-ray sources of high spectral brilliance, a narrow spectral bandwidth of ≃ 1 − 100 meV, and a high repetition rate of ≃ 1 MHz. A diagnostic tool is required to measure CBXFEL spectra with a meV resolution on a shot-to-shot basis.

The CBXFEL hard X-ray spectrograph is designed to image 9.831 keV X-rays in a ≃ 200 meV spectral window and with a spectral resolution of a few meV using an LCLS XFEL (Linac Coherent Light Source X-ray Free Electron Laser) source at the SLAC National Laboratory. We use Bragg reflecting Ge crystals (C1 and C2) arranged in an asymmetric scattering geometry with cumulative asymmetry parameter b∪n = b1b2 = 1 as the dispersing elements, a Be compound refractive lenses (CRL) as focusing element, and YAG-scintillator-based μm-resolution X-ray imagers.

The test experiments are performed at the Advanced Photon Source (APS) beamline 1BM-B. The spectrograph operates close to design specification featuring a 200 meV (FWHM) spectral window of imaging and a 1.4 μm/meV linear dispersion rate. A 40 meV broad reference absorption line produced by an X-ray transparent diamond crystal in the 440 Bragg backreflection is imaged by the spectrograph as a 43 meV broad absorption feature, indicating a ≃ 16 meV spectrograph spectral resolution.

Access Setting

Dissertation-Open Access

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