A5019327211- Particle Accelerators and Free-Electron Lasers
- Particle accelerators and beam dynamics
- Photocathodes and Microchannel Plates
- Gyrotron and Vacuum Electronics Research
- Superconducting Materials and Applications
- Electron and X-Ray Spectroscopy Techniques
- Particle Detector Development and Performance
- Plasma Diagnostics and Applications
- Advanced X-ray Imaging Techniques
- Advanced Electron Microscopy Techniques and Applications
- Radiation Therapy and Dosimetry
- Nuclear and radioactivity studies
- Magnetic confinement fusion research
- Advancements in Photolithography Techniques
- Atomic and Molecular Physics
- Reliability and Maintenance Optimization
- Graphite, nuclear technology, radiation studies
- Integrated Circuits and Semiconductor Failure Analysis
- Astrophysics and Cosmic Phenomena
- Plant Pathogens and Resistance
- Advanced Thermodynamic Systems and Engines
- Scientific Measurement and Uncertainty Evaluation
- Cyclone Separators and Fluid Dynamics
- Plant Disease Resistance and Genetics
- Powdery Mildew Fungal Diseases
Xelera Research (United States)
2016-2024
Cornell University
2012-2022
Brookhaven National Laboratory
2018-2021
Thomas Jefferson National Accelerator Facility
2019
We present a detailed study of the six-dimensional phase space electron beam produced by Cornell Energy Recovery Linac Photoinjector, high-brightness, high repetition rate (1.3 GHz) DC photoemission source designed to drive hard x-ray energy recovery linac (ERL). A complete simulation model injector has been constructed, verified measurement, and optimized. Both horizontal vertical 2D transverse spaces, as well time-resolved (sliced) space, were simulated directly measured at end for 19 77...
We present the results of transverse emittance and longitudinal current profile measurements high bunch charge (≥100 pC) beams produced in DC gun-based Cornell energy recovery linac photoinjector. In particular, we show that cathode thermal core beam emittances dominate final 95% measured at 9–9.5 MeV. Additionally, demonstrate excellent agreement between optimized 3D space simulations measurement, quality laser distribution limits optimal simulated emittances. These results, previously...
Energy recovery has been achieved in a multipass linear accelerator, demonstrating technology for more compact particle accelerators operating at higher currents and reduced energy consumption. delivered to the beam during first four passes through accelerating structure was recovered subsequent decelerating passes. High-energy efficiency by use of superconducting cavities permanent magnets. The fixed-field alternating-gradient optical system used return loop successfully transported...
Characterization of 9--9.5 MeV electron beams produced in the dc-gun based Cornell photoinjector is given for bunch charges ranging from 20 pC to 2 nC. Comparison measured emittances and longitudinal current profiles optimized 3D space charge simulations yields excellent agreement up 1 nC when laser distribution used generate initial particle distributions simulation. Analysis scaling emittance with shows that scales roughly as square root 300 pC, above which trend becomes linear. These...
We measure the tradeoff between quantum efficiency and intrinsic emittance from a NaKSb photocathode at three increasing wavelengths (635, 650, 690 nm) or below energy of bandgap plus electron affinity, hν≤Eg+Ea. These measurements were performed using high voltage dc gun for varied surface fields 1.4−4.4 MV/m. Measurements are two different methods found to agree. At longest wavelength available, nm, was 0.26 μm/mm-rms with ∼10−4. The suitability emitting threshold various low applications...
RNA sequencing (RNA-seq) and genotyping-by-sequencing (GBS) were used for single nucleotide polymorphism (SNP) identification from two economically important obligate plant pathogens, Pseudoperonospora cubensis P. humuli. Twenty isolates of 19 humuli genotyped using RNA-seq GBS. Principle components analysis (PCA) each data set showed genetic separation between the species. Additionally, results supported previous findings that squash are genetically distinct cucumber cantaloupe isolates. A...
The intrinsic emittance of electron beams generated from a multi-alkali photocathode operated in high voltage DC gun is reported. showed sensitivity extending to the infrared part spectrum up 830 nm. measured emittances with light having wavelength longer than 800 nm are approaching limit imposed by thermal energy electrons at room temperature quantum efficiencies comparable metallic photocathodes used operation modern photoinjectors.
We present the results of multiobjective genetic algorithm optimizations a single-shot ultrafast electron diffraction beam line utilizing 225 kV dc gun with novel cryocooled photocathode system and buncher cavity. Optimizations transverse projected emittance as function bunch charge are presented discussed in terms scaling laws derived saturation limit. Additionally, optimization coherence length final rms at sample location have been performed for three different radii: 50, 100, $200\text{...
We present a comparison between space charge calculations and direct measurements of the transverse phase dominated electron bunches from high voltage dc photoemission gun followed by an emittance compensation solenoid magnet. The were performed using double-slit measurement system over range bunch current values. data are compared with detailed simulations 3D codes GPT Parmela3D. initial particle distributions generated measured temporal laser beam profiles at photocathode. brightness as...
Multiobjective genetic algorithm optimizations of a single-shot ultrafast electron diffraction beam line comprised $100\text{ }\text{ }\mathrm{MV}/\mathrm{m}$ 1.6-cell normal conducting rf (NCRF) gun, as well nine-cell $2\ensuremath{\pi}/3$ bunching cavity placed between two solenoids, have been performed. These include optimization the normalized transverse emittance function bunch charge, coherence length rms at sample location for fixed charge $1{0}^{6}$ electrons. Analysis resulting...
This design report describes the construction plans for world's first multi-pass SRF ERL. It is a 4-pass recirculating linac that recovers beam's energy by 4 additional, decelerating passes. All beams are returned deceleration in single beam pipe with large-momentum-aperture permanent magnet FFAG optics. Cornell University has been pioneering new class of accelerators, Energy Recovery Linacs (ERLs), characteristic set parameters. Technology prototyped essential any high brightness electron...
High quantum efficiency alkali antimonide photocathodes have been grown over both stainless steel and glass substrates using sequential evaporation of Sb, K, Rb, Cs. Quantum efficiencies well above 25% measured at 400 nm. A bi-alkali Rb-K-Sb photocathode on a substrate has installed in high voltage DC gun Cornell University the intrinsic electron beam emittance was different photon energies.
Cornell University has prototyped technology essential for any high brightness electron ERL. This includes a DC gun and an SRF injector Linac with world-record current normalized in bunch train, high-current CW cryomodule, high-power beam stop, several diagnostics tools high-brightness beams, e.g. slid measurements 6-D phase-space densities, fast wire scanner profiles, loos diagnostics. All these are now available to equip one-cryomodule ERL, laboratory space been cleared out is radiation...
We present the design of a high repetition rate MeV energy ultrafast electron diffraction instrument based on dc photoelectron gun and an superconducting rf (SRF) linac with multiple independently controlled accelerating bunching cavities. The is existing Cornell photoinjector, which can readily be applied to presented findings. Using particle tracking simulations in conjunction multiobjective genetic algorithm optimization, we explore smallest bunch lengths, emittance, probe spot sizes...
We present a new method for computing the transverse transfer matrix superimposed axisymmetric rf and solenoid field maps. The algorithm constructs directly from one-dimensional maps without numerical derivatives or eigenfunction expansions of map data. In addition, this accurately describes dynamics low energy particles starting solenoid-immersed cathode, allowing to simulate transport through both electrostatic guns. Comparison particle tracking with matrix, direct integration equations...
Advanced simulation codes now exist that can self-consistently solve Maxwell's equations for the combined system of an rf cavity and a beam bunch. While these simulations are important complete understanding dynamics in cavities, they require significant time computing power. These techniques therefore not readily included real useful to physicist during operations. Thus, there exists need simplified algorithm which simulates realistic fields significantly faster than self-consistent codes,...
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...