A5008389421- Advanced X-ray Imaging Techniques
- Particle Detector Development and Performance
- Advanced X-ray and CT Imaging
- Advanced Semiconductor Detectors and Materials
- Metal and Thin Film Mechanics
- Medical Imaging Techniques and Applications
- High-pressure geophysics and materials
- Microstructure and mechanical properties
- Diamond and Carbon-based Materials Research
- Adhesion, Friction, and Surface Interactions
- Cardiac, Anesthesia and Surgical Outcomes
- Advanced Materials Characterization Techniques
- Hip and Femur Fractures
- Digital Holography and Microscopy
- Titanium Alloys Microstructure and Properties
- Ancient Egypt and Archaeology
- High Temperature Alloys and Creep
- Magnesium Alloys: Properties and Applications
- Image Processing Techniques and Applications
- Advanced Condensed Matter Physics
- Tribology and Wear Analysis
- High-Velocity Impact and Material Behavior
- Surface Roughness and Optical Measurements
- Water Systems and Optimization
- Historical and Architectural Studies
Cornell University
2013-2021
Cornell High Energy Synchrotron Source
2014
Heidelberg University
2009
University Hospital Heidelberg
2009
Yale University
2000
Swiss Federal Institute of Aquatic Science and Technology
1991
ABB (Switzerland)
1989
The routine atomic resolution structure determination of single particles is expected to have profound implications for probing structure-function relationships in systems ranging from energy-storage materials biological molecules. Extremely bright ultrashort-pulse X-ray sources - free-electron lasers (XFELs) provide X-rays that can be used probe ensembles nearly identical nanoscale particles. When combined with coherent diffractive imaging, these objects imaged; however, as the images...
We have developed two techniques for time-resolved x-ray diffraction from bulk polycrystalline materials during dynamic loading. In the first technique, we synchronize a fast detector with loading of samples at strain rates ∼103–104 s−1 in compression Kolsky bar (split Hopkinson pressure bar) apparatus to obtain situ patterns exposures as short 70 ns. This approach employs moderate energies (10–20 keV) and is well suited weakly absorbing such magnesium alloys. The second technique useful...
A wide-dynamic-range imaging X-ray detector designed for recording successive frames at rates up to 10 MHz is described. with frame of 6.5 have been experimentally verified. The pixel design allows 8-12 be stored internally high speed before readout, which occurs a 1 kHz rate. An additional mode operation the integration capacitors re-addressed repeatedly readout can enhance signal-to-noise ratio cyclical processes. This detector, along modern storage ring sources provide short (10-100 ps)...
Pixel Array Detectors (PADs) consist of an x-ray sensor layer bonded pixel-by-pixel to underlying readout chip. This approach allows both the and custom pixel electronics be tailored independently best match imaging requirements. Here we present characterizations CdTe sensors hybridized with two different charge-integrating chips, Keck PAD Mixed-Mode (MM-PAD), developed previously in our laboratory. The architecture each these PADs extends instantaneous counting rate by many orders magnitude...
Several charge integrating CMOS pixel front-ends utilizing removal techniques have been fabricated to extend dynamic range for x-ray diffraction applications at synchrotron sources and free electron lasers (XFELs). The pixels described herein build on the Mixed Mode Pixel Array Detector (MM-PAD) framework, developed previously by our group perform high imaging. These new boast several orders of magnitude improvement in maximum flux over MM-PAD, which is capable measuring a sustained excess...
Abstract Actinide materials exhibit strong spin–lattice coupling and electronic correlations, are predicted to host new emerging ground states. One example is piezomagnetism magneto-elastic memory effect in the antiferromagnetic Mott-Hubbard insulator uranium dioxide, though its microscopic nature under debate. Here, we report X-ray diffraction studies of oriented dioxide crystals pulsed magnetic fields. In state a [888] Bragg peak follows bulk magnetostriction that expands Upon reversal...
We have developed calibration and data processing techniques optimized specifically for photon-integrating pixel array detectors (PADs). Primary effects to be calibrated are gain variation area variation. Gain variations originate in electronics may corrected via a multiplicative factor. In contrast, result from doping inhomogeneities the sensor diode, which induce lateral fields that disturb path of charge carriers as they traverse resulting mapped each pixel, depending on x-ray energy....
We studied the properties of chromium compensated GaAs when coupled to charge integrating ASICs as a function detector temperature, applied bias and X-ray tube energy. The material is photoresistor can be biased collect either electrons or holes by pixel circuitry. Both are here. Previous studies have shown substantial hole trapping. This trapping other sensor give rise several non-ideal effects which include an extended point spread function, variations in effective size, rate dependent...
A theory for obtaining meniscus forces and profiles any given liquid-mediated interface is presented that includes the effects of surface interactions, adsorption evaporation liquid films. The force obtained from derivative total free energy interface, which requires profile to be known. solution a second-order differential equation, as derived Pascal’s law static incompressible liquids with inclusion interactions. For nonvolatile films, amount at conserved quantity, whereas volatile...
CdTe is increasingly being used as the x-ray sensing material in imaging pixel array detectors for x-rays, generally above 20 keV, where silicon sensors become unacceptably transparent. Unfortunately suffers from polarization, which can alter response of over time and with accumulated dose. Most prior studies long integration times or that was not hole-collecting Schottky type. We investigated temporal type on timescales ranging tens nanoseconds to several seconds. found shows signal...
Modern storage rings are readily capable of providing intense x-ray pulses, tens picoseconds in duration, millions times per second. Exploiting the temporal structure these sources opens avenues for studying rapid structural changes materials. Many processes (e.g. crack propagation, deformation on impact, turbulence, etc.) differ detail from one sample trial to next and would benefit ability record successive images with single sensitivity while framing at 5 10 MHz rates. To this end, we...
The objective of this paper is to demonstrate, from experiments and modeling, how why molecular orientation functional end groups perfluoro-polyether (PFPE) lubricants play an important role in the tribological performance thin film magnetic disks. These disks typically have amorphous carbon overcoat upon which a lubricant layer deposited using dip-coating technique. Glancing-angle FTIR (Fourier Transform Infra-Red Spectrometry) used for measuring planer groups. A index (MOI) was defined as...
Experiments at storage ring light sources as well next-generation increasingly require detectors capable of high dynamic range operation, combining low-noise detection single photons with large pixel depth. XFEL in particular provide pulse intensities sufficiently that a purely photon-counting approach is impractical. The High Dynamic Range Pixel Array Detector (HDR-PAD) project aims to extending from single-photon sensitivity 106 photons/pixel while maintaining the ability tolerate...
The objective is to route sewage through a combined sewer by means of real time control system. task formulated as mathematical network optimization problem. system simplified be set linearly operating nodes and arcs. Tests indicate that the results obtained are comparable linear programming solutions. However, much larger systems can handled. algorithm fast enough have it applied on AT-PC's for world systems.
There is a compelling need for high frame rate imaging detector with wide dynamic range, from single x-rays/pixel/pulse to >106 x-rays/pixel/pulse, that capable of operating at both x-ray free electron laser (XFEL) and 3rd generation sources sustained fluxes > 1011 x-rays/pixel/s [1, 2, 3]. We propose meet these requirements the High Dynamic Range Pixel Array Detector (HDR-PAD) by (a) increasing speed charge removal strategies [4], (b) integrator range implementing adaptive gain [5], (c)...
Pixel Array Detectors (PADs) consist of an x-ray sensor layer bonded pixel-by-pixel to underlying readout chip. This approach allows both the and custom pixel electronics be tailored independently best match imaging requirements. Here we describe hybridization CdTe sensors two different charge-integrating chips, Keck PAD Mixed-Mode (MM-PAD), developed previously in our laboratory. The architecture each these PADs extends instantaneous counting rate by many orders magnitude beyond that...
New and improved synchrotron radiation sources enable experiments that demand the ability to acquire successive hard (e.g., 10 keV) x-ray images at sub-microsecond rates or quickly patterns encompassing intensities vary by 10^6 more across single images. We describe two novel integrating Pixel Array Detectors (PADs) developed Cornell University accomplish these objectives. The Mixed-Mode PAD (MM-PAD) frames > 1 KHz can readily detect signals within a image ranging from x-rays over 107...