A5022959401- Diamond and Carbon-based Materials Research
- Laser-Plasma Interactions and Diagnostics
- Particle Accelerators and Free-Electron Lasers
- Particle accelerators and beam dynamics
- Semiconductor materials and devices
- Electron and X-Ray Spectroscopy Techniques
- Photocathodes and Microchannel Plates
- Laser-induced spectroscopy and plasma
- Electronic and Structural Properties of Oxides
- Semantic Web and Ontologies
- Laser-Matter Interactions and Applications
- Advanced Database Systems and Queries
- Laser Design and Applications
- Integrated Circuits and Semiconductor Failure Analysis
- Gyrotron and Vacuum Electronics Research
- Service-Oriented Architecture and Web Services
- Magnetic confinement fusion research
- Plasma Diagnostics and Applications
- Ga2O3 and related materials
- GaN-based semiconductor devices and materials
- Advanced Surface Polishing Techniques
- Radiation Effects in Electronics
- Spectroscopy and Laser Applications
- Advanced Semiconductor Detectors and Materials
- VLSI and Analog Circuit Testing
Los Alamos National Laboratory
2021-2025
Arizona State University
2021
Cornell University
2021
George Washington University
2021
Tech-X Corporation (United States)
2006-2017
Lawrence Berkeley National Laboratory
2004-2017
Brookhaven National Laboratory
2009-2017
BAE Systems (Sweden)
2009
University of Arkansas at Fayetteville
2008
Tech-X (United Kingdom)
2007
The pursuit to operate photocathodes at high accelerating gradients increase brightness of electron beams is gaining interests within the accelerator community, particularly for applications such as free lasers (FEL) and compact accelerators. Cesium telluride (Cs2Te) a widely used photocathode material it presumed offer resilience higher because its wider band gap compared other semiconductors. Despite advantages, crucial properties Cs2Te remain largely unknown both in theory experiments. In...
High quantum yield, low transverse energy spread, and prompt response time make GaAs activated to negative electron affinity an ideal candidate for a photocathode in high brightness photoinjectors. Even after decades of investigation, the exact mechanism emission from is not well understood. Here, photoemission such photocathodes modeled using detailed Monte Carlo transport simulations. Simulations show quantitative agreement with experimental results efficiency, distributions emitted...
Plasma-based accelerators can sustain accelerating gradients on the order of 100 GV/m. If plasma is not fully ionized, fields this magnitude will ionize neutral atoms via electron tunneling, which completely change dynamics wake. Particle-in-cell simulations a high-field wakefield accelerator, using OOPIC code [D. L. Bruhwiler et al., Phys. Rev. ST Accel. Beams 4, 101302 (2001)], includes field-induced tunneling ionization Li gas, show that presence even moderate gas density significantly...
The diamond amplifier (DA) is a new device for generating high-current, high-brightness electron beams. Our transmission-mode tests show that, with single-crystal, high-purity diamonds, the peak current density greater than 400 mA/mm², while its average can be more 100 mA/mm². gain of primary electrons easily exceeds 200, and independent their within practical range DA applications. We observed emission. maximum emission measured was 40, bunch charge 50 pC/0.5 mm². There 35% probability an...
A promising new concept of a diamond-amplified photocathode for generation high-current, high-brightness, and low thermal emittance electron beams was recently proposed is currently under active development. Detailed understanding physical processes with multiple energy time scales required to design reliable efficient diamond-amplifier cathodes. We have implemented models, within the VORPAL computational framework, simulate secondary charge transport in diamond order facilitate...
<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> When evaluating sub-100 nm circuits for hardness to Single Event Transients (SETs), the choice of strike model is shown have a notable effect upon observed upsets. A method utilizing distributed charges strikes adjacent devices illustrated and utilized compare kernel models in such Charge Sharing SETS (CSSETS). Bias-dependent are more accurately predict expected physical observations Technology...
A hydrogen-terminated diamond is a proven efficient electron emitter that can support emission of high average current. Several factors dictate the amplifier's gain: number secondary electrons created at their point entry into diamond, fraction transmitted to emitting face, and emitted. In this paper, we present model detailing impact charge trapping surface on instantaneous electric field inside its effect transmission gain. The ratio emitted depends electron's energy distribution barrier....
In this work we adapt an efficient information integration algorithm to identify the minimal set of potentially relevant Semantic Web data sources for a given query. The vast majority these are files written in RDF or OWL format, and must be processed their entirety. Our adaptation includes enhancing with taxonomic reasoning, defining using mapping language purpose aligning heterogeneous ontologies, introducing concept source relevance reduce number that need consider After selection...
We developed modeling capabilities, within the Vorpal particle-in-cell code, for three-dimensional simulations of surface effects and electron emission from semiconductor photocathodes. They include calculation probabilities using general, piece-wise continuous, space-time dependent potentials, effective mass, band bending field effects. applied these models, in combination with previously implemented capabilities charge generation transport diamond, to investigate dependence on electric...
Detailed measurements of momentum distributions emitted electrons have allowed the investigation thermal limit transverse emittance from metal photocathodes. Furthermore, recent developments in material design and growth resulted photocathodes that can deliver high quantum efficiency are sufficiently robust to use electric field gradient photoinjectors free electron lasers. The process usually produces photoemissive layers with rough surface profiles lead accelerating fields possible work...
The anticorrelation between quantum efficiency (QE) and electron spin polarization (ESP) from a p-doped GaAs activated to negative affinity is studied in detail using an ensemble Monte Carlo approach. photoabsorption, momentum relaxation during transport, tunneling of electrons through the surface potential barrier are modeled identify fundamental mechanisms, which limit spin-polarized sources. In particular, we study response QE ESP various parameters, such as photoexcitation energy, doping...
Diffractive spreading of a laser pulse imposes severe limitations on the acceleration length and maximum electron energy in wake field accelerator (LWFA). Optical guiding via plasma channels can extend laser-plasma interaction distance over many Rayleigh lengths. Energy efficient coupling pulses into through is very important for optimal LWFA performance. Results from simulation parameter studies channel using particle-in-cell (PIC) code VORPAL [C. Nieter J. R. Cary, Comput. Phys. 196, 448...
Diamond is a unique material for x-ray energy conversion. Its high thermal conductivity and low coefficient of expansion make it ideal heat load environments. High strength transmission also are potentially useful features certain applications in science. However, its large bandgap, while offering insensitivity to visible light, makes charge trapping more likely (thermal detrapping less likely) than silicon; conversion efficiency 3-4 times even under the best conditions. Limitations...
The Relativistic Heavy Ion Collider (RHIC) contributes fundamental advances to nuclear physics by colliding a wide range of ions. A novel electron cooling section, which is key component the proposed luminosity upgrade for RHIC, requires acceleration high-charge bunches with low emittance and energy spread. promising candidate source recently developed concept high quantum efficiency photoinjector diamond amplifier. We have started implement algorithms, within VORPAL particle-in-cell...
The physics interest in a luminosity upgrade of RHIC requires the development cooling-frontier facility. Detailed calculations were made electron cooling stored beams. This has been followed by beam dynamics simulations to establish feasibility creating necessary beam. accelerator will be superconducting Energy Recovery Linac (ERL). An intensive experimental R&D program engages various elements accelerator, as described 24 contributions 2007 PAC.
Views Icon Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Twitter Facebook Reddit LinkedIn Tools Reprints and Permissions Cite Search Site Citation Erik M. Muller, Mengjia Gaowei, Ilan Ben-Zvi, Dimitre A. Dimitrov, John Smedley; Carbon edge response of diamond devices. Appl. Phys. Lett. 3 March 2014; 104 (9): 093515. https://doi.org/10.1063/1.4868135 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks...
As the demand for complex functions to be performed in harsh environments such as space applications converges with continually diminishing IC feature sizes, traditional methods of circuit design and evaluation break down. The flow is mostly concerned electrical interactions, some cases considering power thermal effects. Proposed a method integrating radiation expertise into this flow. Specifically, effect ionizing upon transient performance digital analog circuits targeted. questions...
Separate data sources on related domains of knowledge generally contain different but complementary information. There are queries that can only be answered with pieces information from some the separate sources. Thus, it is considerable interest to enable query answering based searching in an integrated collection However, independently developed and evolved use schemas represent their data. This makes difficult search way. To address this problem, we have end-to-end integration system...
We present an efficient search approach for selecting all potentially relevant data sources a conjunctive Semantic Web query. use map ontologies to align heterogeneous domain ontologies. This allows us select that may be the query but generally do not describe their directly in terms of ontology The "goal node search" algorithm is significant improvement on our original source selection algorithm. new more expressive knowledge representation language and it about three times than when...
We present ISENS, a distributed, end-to-end, ontology-based information integration system. In response to user's query, our system is capable of retrieving facts from data sources that are found in the surface semantic Web as well inthe Deep Web. Furthermore, it retrieves where not directly described terms query ontology. Instead, its ontology can be translated using mapping axioms. solution, we use concept source relevance summarize content source. Our then this select needed answer given...
Abstract The LANSCE accelerator facility has been in operation for 50 years performing important scientific support national security. unique feature of the is multi-beam operation, delivering beams to five experimental areas. To reduce long-term operational risks and realize future beam performance goals laboratory missions, we are developing a novel high-brightness Front End injector. proposed injector includes two independent low-energy transports H + - merging at entrance single RFQ....