2017 March 15 - April 24
2017 May 17 - June 29
2017 BTR deadline: 04/17/17
2017 October 11 - December 21
2017 Proposal deadline: 08/01/17
2017 BTR deadline: 09/10/17
November 10, 2006
Sturt Manning, Director
Cornell Tree-Ring Laboratory and Professor, Department of Classics, Cornell University
"Extracting Information from Wood: Chronology, Climate and Environmental Impacts from Tree-rings"
Abstract: Tree-rings provide rich archives for the high-resolution (annual to sub-annual) study of the past - from dating ancient monuments and archaeological contexts (dendroarchaeology) through geomorphological processes (dendrogeomorphology) to the investigation of past climate analysis and its reconstruction (dendroclimatology) to chemical investigation and analysis of the traces of past pollution histories and environmental events (e.g. large volcanic eruptions) as recovered from the annual growth rings. This talk will consider the challenges and opportunities for sophisticated tree-ring based research, in particular focused on work involving the Cornell Tree-Ring Laboratory, and using the example of the attempts to date and resolve major volcanic eruptions in the past from tree-rings.
October 13, 2006
Gil Toombes, Graduate Student
Physics Department, Cornell University
"Holey Sheets and Crossed Concertinas: Sculpting Silica with ABC Block Copolymers"
Abstract: Organisms such as diatoms and sponges produce organic-silica composites with complex, hierarchical structures and outstanding material properties. Mimics of biological ceramics have been made using surfactants or amphipathic molecules to guide the structure of inorganic precursors. In a block copolymer, chemically dissimilar polymer chains (blocks) are covalently linked together. These blocks may micro-phase separate into nanometer-scale domains arranged in periodic lattices. By combining a silica sol with a block copolymer, the silica can be patterned with the domain structure of the block copolymer and several morphologies have been formed using AB di-block copolymers. For ABC tri-block copolymers, the third distinct block results in a zoo of interesting structures and we have recently confirmed that these structures can be formed in silica.
September 22, 2006
Arthur Woll, Staff Scientist
CHESS, Cornell University
"Quantitative Analysis and Software Tools for Confocal X-ray Fluorescence Data Analysis at CHESS"
September 8, 2006
Ken Finkelstein, Staff Scientist
CHESS, Cornell University
"X-ray Detected Magnetic Resonance: using x-rays scattered spins to measure magnetic and electronic properties of solid liquids, possibly under extreme conditions, very likely with the ERL"
September 1, 2006
Aram Amassian, Postdoctoral Research Associate
Cornell Center for Research, Cornell University
"Subplantation and Interface Modification During Ion Bombardment-assisted Deposition of Amorphous Oxides: In-situ Real-time Spectroscopic Ellipsometry and Monte-Carlo Simulation Study"
Abstract: Significant research effort has been devoted to linking plasma characteristics, ion-surface interactions, and film properties in physical vapour deposition (PVD), plasma-enhanced chemical vapour deposition (PECVD), and hybrid PECVD/PVD processes, leading to a qualitative understanding of surface processes and thin film growth mechanisms. In this talk, we report on new methodology used to gain a quantitative understanding of ion-surface interactions, including subplantation, during plasma treatment of surfaces and plasma deposition of thin films. Using in situ real-time spectroscopic ellipsometry (RTSE), we have obtained time-resolved quantitative information about depth-dependent modifications of c-Si(001) exposed to intense ion bombardment under conditions typically used for amorphous oxide deposition. The in situ experimental study was complemented by Monte-Carlo TRIDYN simulations, which were modified to calculate dynamic changes in the structure and composition of a target exposed to a broad-energy ion source (RF plasma source and corresponding ion energy distribution function) at high fluence. This novel approach has allowed us to obtain the first quantitatively accurate simulation results of ion bombardment-induced sub-surface oxygen incorporation on time-scales from << 1 s up to a few minutes.
This talk will illustrate some of the effects of subplantation with the use of practical examples, such as interface broadening in TiO2/SiO2 multilayer Bragg reflectors, porosity and interface control in dense-porous Si3N4 multilayer devices, and enhanced oxygen incorporation in bias-assisted magnetron sputtered ITO coatings. Additional examples of growth studies featuring in situ RTSE will be presented if the time allows it.
August 25, 2006
Stefan Kycia, Professor of Physics
University of Guelph
"From the Brazilian Synchrotron to the Synchrotron in Saskat Dynamical X-ray Diffraction from Quasicrystals"
Abstract: I will first introduce the LNLS Brazilian Synchrotron and describe some of our recent achievements. Then an introduction of the CLS Canadian Light Source in Saskatchewan. This will include the proposed "Brockhouse Sector" for x-ray diffraction and scattering. Finally, our most recent results of dynamical x-ray diffraction and multiple beam diffraction from Al-Pd-Mn quasicrystals will be presented.
SPECIAL DATE & TIME
Tuesday, August 15, 2006
Professor Richard Jones, Professor of Physics
University of Connecticut
"Diamonds, High Energy Physics and X-rays"
Professor Jones is a high energy physicist who has been working on detector systems that utilize very high quality single crystal diamonds manufactured by De Beers in Europe. He has done x-ray characterization (topography) of diamonds at Daresbury and (since SRS is shutting down) is interested in finding another synchrotron source.
Professor Jones has agreed to describe for us his research, what he has done and what he would like to do on this project.
SPECIAL DATE & TIME
Tuesday, August 1, 2006
Professor Ajay Gupta, Center Director, UGC-DAE Consortium for Scientific Research, Indore, India
"Depth Resolved Structural Studies in Multilayer Nanostructures using X-Waves"
Abstract: Thin films and multilayers have emerged as an important class of nanostructured materials with immense possibilities of tailoring their properties in order to achieve the desired functionality. Interfacial region plays a dominant role in determining the properties of multilayers. Therefore, it is important to elucidate the interface structure in multilayers in order to understand their novel properties as well as to tailor the same through tailoring the interface structure. Since the width of the interfacial region ranges from a fraction of a nm to a few nm, it is necessary to use experimental techniques with a depth resolution of 1 nm or better. X-ray based techniques like fluorescence, XRD, SAFS, and Nuclear Resonance Scattering are powerful techniques for structural characterization. In general, x-rays being highly penetrating radiation, these techniques lack depth resolution. However, X-ray standing waves (XSW) formed by the superposition of two coherently coupled X-ray beams, make it possible to localize the X-ray intensity into anti-nodal regions of an XSW field, and thereby attain a spatially localized periodic probe with a length scale equivalent to the period of XSW.
In the present talk the use of XSW will be demonstrated in: i) determining elemental concentration profiles through fluorescence measurement, ii) measurement of concentration profile of a specific isotope (e.g. 57 Fe) by making use of nuclear resonance fluorescence, iii) depth resolved XAFS and nuclear forward scattering. The examples taken include, i) study of the effects of swift heavy ion irradiation on metal/silicon systems, ii) characterization of magnetic multilayers, and iii) measurement of self-diffusion of Fe in amorphous and nanocrystalline alloys.
SPECIAL DATE & TIME
Tuesday, July 18, 2006
Professor Melville P. Ulmer, Director, Astrophysics Program, Northwestern University
"Multilayers and Adaptive X-ray Optics: From Blue Sky to The Blue Planet"
Abstract: I will discuss the considerations that go into formulating X-ray optics designs for 20-70 keV X-ray telescopes. This will provide the background to allow you to understand why we X-ray astronomers want to put multilayers on the inside of replicated X-ray optics. And also why adaptive optics with novel magneto-strictive thin films is attractive to us. I then describe progress we have made, requirements for the Brookhaven NSLS2, and some ideas I have for synchrotron X-ray imaging that may or may not need multilayers and may or may not work!
July 14, 2006
Dr. Raimond Ravelli, Team Leader
European Molecular Laboratory, Grenoble France
May 5, 2006
Dr. Zhongwu Wang
Los Alamos National Lab
"Exploring the Pressure-induced Phenomena of Materials and Resulting Mechanisms"
High-pressure cells combined with a variety of in-situ probes have been developed to study the pressure-induced phenomena and resulting mechanism of materials. While new generation synchrotron radiation sources coupled with DAC enable one to perform a wide range of in-situ spectroscopic measurements at extreme P-T conditions, the newly developed carbon nanotube cell with High Resolution Transmission Electron Microscopy (HRTEM) allows one to directly observe and real time record the atomic movement of deformation and further phase transformation of materials under in-situ compression.
I will briefly introduce the DAC and newly developed carbon nanotube pressure techniques with their applications, and further highlight our key research results. These include high pressure melting measurement and modeling, phase transformation and EOS of earth materials with application to the lower mantle and core-mantle boundary, superhard materials (hardness, yield strength, toughness of single crystal and tough composite), nanotechnology (morphology, interplay, stress and strain distribution, and mechanical performance with application in design strong nano-building blocks), energetic and future energy materials, and the carbon state under cosmic ray conditions.
April 28, 2006
Dr. Atsushi Kubo
"Post-perovskite Phase Transition at the Base of Earth's Lower Mantle and Pressure Scales to Megabar Range"
Abstract: Earth’s lower mantle is known as a monotonic region in terms of depth-variation of seismic wave speeds. However, at the base of the lower mantle, various types of seismic anomalies have been reported, and the reason for the anomaly has been enigmatic. Very recently, post-perovskite phase transition was discovered in MgSiO3 composition at ~120 GPa and ~2500 K by means of high-P/T in situ x-ray diffraction experiments using laser-heated diamond anvil cells. Because many seismic anomalies could be explained by physical properties of the layer-structured post-perovskite phase (CaIrO3-type structure, space group Cmcm), earth scientists are extensively working on this phase to determine precise location of phase boundary in P/T space, equation of state, and slip systems under plastic deformations.
Progress of the experimental study of the post-perovskite phase revealed inconsistency in the pressure scales (e.g. Au, Pt). The difference of pressure values at megabar pressure range could reach ~20 GPa at 150 GPa range. This has been preventing determination of accurate pressure of the post-perovskite phase boundary. In the talk, a brief review of progress of experimental studies on post-perovskite phase will be presented, and the direction to experimentally determine precise location of post-perovskite phase boundary will be discussed.
April 21, 2006
Dr. Haozhe Liu, HPCAT
Carnegie Institution of Washington
Advanced Photon Source
"In-situ X-ray Diffraction Studies for the Materials Under High Pressure"
Abstract: The current state-of-the-art diamond anvil cell (DAC) techniques combined with synchrotron x-ray techniques make x-ray diffraction (XRD) studies one of most active, burgeoning fields in the high pressure community. The equation of state, pressure induced phase transition (or amorphization, or crystallization), Rietveld structural refinement, elastic anisotropy, strain and stress, yield strength, preferred orientation etc. information can be obtained by using axis and radial diffraction techniques in DAC. The selected XRD researches under high pressure performed at ID-B diffraction station of HPCAT for various materials, such as earth materials, simple and complicated oxide compounds, nanostructural materials, metallic glass and amorphous materials, will be presented. The challenge and opportunity for the in situ XRD studies under high pressure will be discussed.
March 24, 2006
Dr. Lothar Strüdar
Max-Planck-Institut fur Extraterrestrische Physik
"High Speed Semiconductor Detectors for the Synchrotron Experiments at LCLS and XFEL"
Abstract: Silicon Drift Detector type detectors (SDDs, pnCCDs, CDDs and active pixel sensors(APS), DEPFETs) have been developed as high speed spectrometers for energies from 50 eV up to 50 keV in a single photon counting mode as well in an integration mode. They show high energy and high position resolution as well as high quantum efficiency for X-rays. Their full well capacities are larger than 105 electrons per pixel. The read noise close to room temperature is less than 10 electrons (rms) leading to Fano limited energy measurements at readout speeds of 108 pixels per second. Pixel sizes of 20 × 20 µm2 have been realized on 500 µm fully depleted silicon as well as pixel sizes up to 1 cm2. Typical formats being experimentally evaluated are 256 × 256 or 512 × 512 with pixel sizes from 35 µm to 75 µm. The typical sensitive detector thickness is 500 µm, a maximum detector thickness is technologically limited to 1.5 mm.
Special designs have been proposed for synchrotron applications complying with the time structure (bunch structure) conditions of the recently approved XFEL to be built at DESY. They are based on the concept of a (non-controlled) controlled drift detectors.
A detector system which satisfies the LCLS specifications is presented on the basis of fully depleted pnCCDs with a format of 1024 x 1024 and a pixel size of 50 µm and a readout rate of 250 Hz.
SPECIAL DATE & TIME
Monday, March 20, 2006
Fabio Malavasi, M.D., Professor of Medical Genetics
Laboratory of Immunogenetics and Research Center on Experimental Medicine, University of Torino Medical School, Torino, Italy
"Intragrating Basic Science into Clinical Diagnosis and Prognosis. The Example of the Human CD38 Gene Family"
Human CD38 is the mammalian prototype of a family of phylogenetically conserved proteins which share structural similarities and enzymatic activities involved in the production of an intracellular second messenger with calcium mobilizing effects. Engagement of CD38 by agonistic monoclonal antibodies and the CD31 ligand initiates a cytoplasmic signaling cascade involving tyrosine phosphorylation of the proto-oncogene c-cbl and of the extracellular regulated kinase 1/2 complex. Further requirements for signal transduction include a privileged localization within the cholesterol-rich areas of the plasma membrane and physical association with specialized surface receptors. CD38-mediated signals are crucial in heterotypic cell adhesion and migration as well as in the activation of proliferation / survival programs by normal and neoplastic cells. Disease models showing an involvement of CD38 and CD157 will be used an analytical tool for investigating the role played /in vivo/ by these molecules: the model adopted is the B cell chronic lymphocytic leukemia (B-CLL). The most recent literature will be reviewed in order to formulate a single model reconciling the enzymatic and receptorial activities of CD38.
March 3, 2006
Department of Materials Science and Engineering, Lawrence Berkeley National Laboratory
"Magnetism at Surfaces and Interfaces of Oxide Thin Films"
Abstract: Surfaces and interfaces of ferromagnetic materials often exhibit properties not found in the bulk. In particular, the surfaces and interfaces of complex oxides materials provide a rich playground for the exploration of novel magnetic properties not found in the bulk constituents but also for the development of functional interfaces to be incorporated into technological applications. Through oxide nanostructure and magnetic tunnel junction studies, we have probed the role of surface and interfaces in highly spin polarized materials. The first part of my talk will focus on oxide nanostructures in which the geometric confinement increases the surface area to volume ratio and alters the strain state of the film. We use photoemission electron microscopy (PEEM) and MFM to probe the magnetism in submicron (La,Sr)MnO3 islands within a non-magnetic matrix patterned by a novel approach of e-beam lithography and ion implantation. PEEM and MFM images reveal that the domain structure in the islands depends predominantly on the shape of the islands, with the magnetocrystalline and magnetoelastic energies contributing secondary effects. We have also studied epitaxial oxide trilayer junctions composed of magnetite (Fe3O4) and doped perovskite manganite (La,Sr)MnO3 ferromagentic electrodes. In these structures, we have varied the composition, hence the Curie temperature, of the barrier layer in order to determine the tunneling mechanism and the origin of the anomalous temperature dependence of the magnetoresistance. Our incorporation of CoCr2O4, NiMn2O4, FeGa2O4 as well as nonmagnetic Mg2TiO4 suggests that conduction is dominate by elastic tunneling at low biases and inelastic hopping at higher biases. We have also taken a closer look at the electrode/barrier interface by X-ray Magnetic Circular Dichroism (XMCD), X-ray Absorption Spectroscopy (XAS) and PEEM and found that long range magnetic order is induced in the barrier by the electrodes, suggesting that a spin filter-magnetic tunnel junction may be a more accurate model for our junctions.
SPECIAL DATE & TIME
February 22, 2006
Materials Science and Technology of Polymers Science and Technology Department, University of Twente
"Nanofabrication of Functional Ordered and Oriented Platforms with Organometallic Block Copolymers"
(M. Roerdink, M. A. Hempenius, and G. J. Vancso)
February 3, 2006
Joel Bernier, Postdoctoral Research Associate
"Quantitative Stress Analysis Using Area Detectors"
Abstract: The more recent availability of high-brilliance, high-energy synchrotron sources and large area detectors has had a significant impact on experimental materials science. In particular, the unique combination of penetration depth, rapid collection times and large area detectors facilitates the characterization of microstructure and micromechanical state in bulk polycrystalline samples subject to thermo-mechanical processing in situ. Distributions of intergranular orientation and stress over the diffraction volume, as well as their evolution with external loading, are available from powder diffraction images. These data are invaluable to the understanding of deformation mechanics and enhancement of structure-based material models.
The present focus is the measurement of lattice strain pole figures using hard, monochromatic x-rays and area detectors. The salient features of currently implemented experimental techniques as well as methods for data analysis are presented along with sample results for a recrystallized Cu sample examined at both CHESS and APS. Given the relative novelty of these measurements, both the experimental hardware and data analysis techniques remain in the early stages of development. The central challenge involves maximizing reciprocal space coverage as well as the accuracy of each scattering vector measurement. In addition, the convenience of a dedicated setup is unlikely in the near future, which limits throughput. The goal is to generate a discussion to identify the current limitations of the instrument and data analysis methods, and to formulate strategies for improving both aspects to better serve the user community.
Joel V. Berniera*, Jun-Sang Parkb and Matthew P. Millerb
aAdvanced Photon Source, Argonne National Laboratory, Argonne, IL 60439
bSibley School of Mechanical & Aerospace Engineering, Cornell University, Ithaca, NY 14853
*corresponding author's email: email@example.com
January 27, 2006
Paul Fenter, Group Leader for Interfacial Processes
Advanced Photon Source, Argonne National Laboratory
"Imaging Structures and Processes at the Mineral-Water Interface with High Resolution X-ray Scattering"
Abstract: The mineral-water interface is the primary site of low-temperature geochemical processes and exerts a strong influence over our environment. Yet our inability to ‘see’ the associated structures and processes in-situ through an aqueous phase strongly impairs our understanding of these systems. X-ray scattering techniques, originally developed to study metal and semiconductor surfaces, offer many new and powerful capabilities to understand these processes in-situ at the mineral-water interface. I will discuss opportunities in this area derived from the application and development of advanced X-ray scattering techniques that incorporate additional elemental and chemical sensitivities with surface specificity and Å-scale resolution, effectively transforming X-ray scattering to an molecular-scale imaging technique. Examples include the determination of interfacial water structure and interfacial ion distributions at mineral-water interfaces with both elemental and chemical sensitivities.
*Supported by the US Department of Energy (BES, Division of Chemical Sciences, Geosciences, and Biosciences)
Atomic and molecular scale phenomena at solid-liquid interfaces, surfaces and other complex interfaces, with an emphasis on in-situ measurements. Specific areas of interest include:
* structure of mineral-water interfaces
* adsorption/association of ions at charged interfaces (electrical double-layer structure)
* structure and growth of organic thin-film structures
* real-time studies of mineral growth and dissolution
January 20, 2006
Remy Tumbar, Senior Research Associate, Department of Molecular Biology and Genetics, Cornell University
"Interferometric Sampling Optical Field Sensors"
Imaging is one of the main methods of data gathering for scientific investigation and in everyday life applications. By far, the biggest challenge is posed by reliably detecting the phase of the field at frequencies within the optical spectrum and higher. Detecting/controlling the phase is key to imaging, a simple result of the Fourier transform relationship between the source distribution and the propagated/received field.
Having reliable phase estimates permits fully digital, quantitative, computational imaging (as in RADAR and ultrasound). It allows information-theoretic-based, automated, target detection, recognition, classification, and tracking. Not having access to the phase has forced us to produce some of the most exquisite and expensive collections of polished glass (e.g. your typical $10,000 microscope objectives), which are, basically, the equivalents of perfect antennas. Furthermore, we need different objectives/lenses for different imaging situations (e.g. field of view, magnification, etc.). Finally, the lack of phase information prevents fully computational imaging, thus preventing the application, in a general fashion, of the powerful information theoretic methods enumerated above.
I will describe a new type of interferometric optical amplitude, phase and polarization sensor, the Sampling Field Sensor (SFS). It combines the highly desirable traits of accuracy and resolution, characteristic to interferometers, with straightforward implementation, compactness, and, most importantly, vibration insensitivity, a world's first for an optical interferometer. I will comment on different physical implementations, some of them applicable outside the visible spectrum (e.g. X-ray). The characteristics of the SFS, enumerated above, allow its use outside the optical lab, wherever imaging is required. Thus, this approach has the potential to morph optical imaging into a truly digital, computational, modality. I will describe some of my past and current efforts in that direction and comment on some of the challenges I have encountered.