A5103151655- Electron and X-Ray Spectroscopy Techniques
- Photocathodes and Microchannel Plates
- Advanced Electron Microscopy Techniques and Applications
- Particle Accelerators and Free-Electron Lasers
- Atomic and Molecular Physics
- Transition Metal Oxide Nanomaterials
- Biofield Effects and Biophysics
- Electromagnetic Fields and Biological Effects
- X-ray Spectroscopy and Fluorescence Analysis
- Ga2O3 and related materials
- Particle accelerators and beam dynamics
- Gyrotron and Vacuum Electronics Research
- Machine Learning in Materials Science
- Human Health and Disease
- Atomic and Subatomic Physics Research
- Cold Atom Physics and Bose-Einstein Condensates
Cornell University
2020-2023
University of Chicago
2021-2022
We report the design and performance of a time-resolved electron diffraction apparatus capable producing intense bunches with simultaneously single digit micrometer probe size, long coherence length, 200 fs rms time resolution. measure 5d (peak) beam brightness at sample location in micro-diffraction mode to be 7×1013 A/m2 rad2 . To generate high bunches, system employs efficiency, low emittance semiconductor photocathodes driven wavelength near photoemission threshold repetition rate up 250...
Ultrafast electron diffraction (UED) is a technique in which short-pulse beams can probe the femtosecond-scale evolution of atomic structure matter driven far from equilibrium. As an accelerator physics challenge, UED imposes stringent constraints on brightness beam. The low normalized emittance employed UED, often at 10 nm scale and below, particularly sensitive to both applied field aberrations space charge effects. role increasingly important small systems that feature multiple orders...
Reducing the intrinsic emittance of photocathodes is one most promising routes to improving brightness electron sources. However, when growth occurs during beam transport (for example, due space charge), it possible that this overwhelms contribution photocathode, and, thus, in case source improvements are not beneficial. Using multiobjective genetic optimization, we investigate role plays determining final several space-charge-dominated photoinjectors, including those for...
In an effort to increase spatial and temporal resolution of ultrafast electron diffraction microscopy, ultrahigh-brightness photocathodes are actively sought improve beam quality. Beam dynamics codes often approximate the Coulomb interaction with mean-field space charge, which is a good approximation in traditional beams. However, point-to-point effects, such as disorder-induced heating (DIH) Boersch effect, cannot be neglected cold, dense beams produced by photocathodes. this paper, we...
We report the design and performance of a time-resolved electron diffraction apparatus capable producing intense bunches with simultaneously single digit micron probe size, long coherence length, $200$ fs rms time resolution. measure 5d (peak) beam brightness at sample location in micro-diffraction mode to be $7 \times 10^{13} \ \mathrm{A}/\text{m}^2\text{-rad}^2$. To generate high bunches, system employs efficiency, low emittance semiconductor photocathodes driven wavelength near...
The application of Multiobjective Genetic Algorithm optimization (MOGA) to photoemission based ultrafast electron diffraction (UED) beamlines featuring extremely low cathode mean transverse energies has lead designs with emittances as 1 nm for sub-picosecond bunches 10⁵ electrons*. Analysis these results shows significant emittance growth during transport: dilution high a factor 200-4000% various and optics settings. In this study we quantify model the individual sources (slice mismatches...