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2014

Aug 21
Thursday

X-ray Imaging of Ultrafast Phase Separation in Magnetite and Spin Injection into Copper

Speaker: Roopali Kukreja, Stanford University
XSD Presentation
432/C010 @ 10:00 AM
View Description
In recent years, there has been a renewed interest in magnetic materials and correlated oxides due to major advance in thin-film growth technology. Materials showing metal insulator transition with orders of magnitude drop in conductivity, have become a potential candidate for novel electronics and photonics devices. While in data storage, the discovery of the Giant Magnetoresistance (GMR) effect has revolutionized read head technology of the hard disk drives. The subsequent discovery of the Spin Transfer Torque phenomenon, where a spin current is used to switch the magnetization, promises to be a good candidate for Magnetic Random Access Memory devices.

In the first part of my talk I will focus on the metal insulator transition (verwey transition) in magnetite triggered by optical excitation. Magnetite (Fe3O4), is the first oxide where a relationship between electrical conductivity and fluctuating/localized charges was observed, with a drop in conductivity by two orders of magnitude at TV=123K. The Verwey transition is also accompanied by a structural change from monoclinic to cubic symmetry. Despite decades of research and indications that charge and orbital ordering play an important role, the mechanism behind the Verwey transition remains unclear. Recently, three-Fe-site lattice distortions called trimerons have been identified as the true microscopic face of electronic order in the low temperature-insulating phase. I have studied the real time response of insulating magnetite to optical excitation with ultrafast soft X-ray scattering as well as optical pump probe experiments and discovered this to be a two-step process. After an initial femtosecond (~300fs) destruction of individual trimerons in the corresponding lattice, a phase separation into residual insulating trimeron and cubic metallic phases on a 1.5 picosecond timescale is observed.

The second part of my talk involves understanding spin transport into the non-magnetic metal Cu from an adjacent Co ferromagnet. It has been predicted that a small non-equilibrium magnetization due to spin accumulation, builds up in Cu near the interface due to differential spin transport across the interface. I have developed an extremely sensitive detection method based on element specific x-ray magnetic circular dichroism microscopy coupled with synchronizing electrical and synchrotron pulses at MHz rates. The sensitivity of this technique has allowed me to detect the extremely small transient Cu magnetization of < 0.0001 B/atom and to show that its sign is the same as that in Co.
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Aug 20
Wednesday

Approaching Protein Dynamics with Coherent X-ray Scattering

Speaker: Dr. Luxi Li
XSD Presentation
436/C010 @ 11:00 AM
View Description
The diffuse scattering of protein crystals contains the information of dynamic disorders (e.g. the atomic and molecular fluctuations) and static disorders (e.g. mosaicity) in the crystals. The biological functions of proteins are related to the intramolecular motions, such as domain fluctuations. This work presents the first approach to protein dynamics in single crystals using X-ray Speckle Visibility Spectroscopy combining with the photon statistics analysis (XSVS-PS). The XSVS-PS technique was benchmarked with the well-known X-ray Photon Correlation Spectroscopy (XPCS) method on the study of Brownian motions in 1% Silica suspension [1]. XSVS is a single-shot technique, which is essential for samples suffering from radiation damage, especially for biological materials. The XSVS measurement on the Concanavalin A (ConA) crystal was performed at the APS 34-ID-C beamline with the fully coherent X-ray beam at room temperature. The diffuse scattering patterns about single Bragg peaks were recorded with a series of different integration times. The diffuse component about a [h0l] reflection peak of the ConA crystal indicates a static disorder on the surface of the crystal with a visibility around 0.6 independent of the integration time. The result supports that the XSVS-PS method is feasible for studying the collective motion of proteins in single crystals. However, the approaching of protein dynamics will need an increase of the X-ray coherent flux by one to two orders of magnitude, which will be achieved by the future MBA upgrade of APS.

[1] Luxi Li, P. Kwasniewski, D. Orsi, L. Wiegart, L. Cristofolini, C. Charona, A. Fluerasu, “Photon Statistics and Speckle Visibility Spectroscopy with Partially Coherent X-rays", J. Synchrotron Rad., accepted, 2014.
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Aug 19
Tuesday

Developing Insights into Catalytic Processes Through in situ Studies: Investigations of Size Selected Clusters and Solution Synthesized Nanoparticles

Speaker: Eric Tyo, Argonne National Laboratory, Material Science Division
XSD Presentation
401/A1100 @ 1:00 PM
View Description
To develop catalytic processes with higher selectivity and activity, fundamental insights need to be gained into the active site specific mechanisms occurring. The most effective way of gathering such insights is by performing in situ studies of well-defined systems. Soft-landed, size and composition selected subnanometer Ag clusters are active for the selective partial oxidation of propylene at relatively low temperatures. Temperature programmed reactivity (TPRx) was performed with in situ synchrotron X-ray characterization, Grazing Incidence Small Angle X-ray Scattering (GISAXS) and X-ray Absorption Spectroscopy (XAS), to determine structural morphology and oxidation state during catalytic activity. Au doped Cu3O4 nanoparticles are also investigated, in a similar method, for the oxidative dehydrogenation of cyclohexane. Significant influence in catalytic activity is observed due to the particle size and doping of Au. These investigations illustrate the power of in situ studies towards developing the fundamental understanding necessary for the directed design of next generation catalysts.
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Aug 19
Tuesday

High-pressure Single-crystal Neutron Scattering Study of the 245 Superconductor

Speaker: Wei Bao, Renmin University of China
XSD Presentation
401/A1100 @ 10:00 AM
View Description
The iron vacancy order and the block antiferromagnetic order exist in the new iron 245 superconductors [1,2]. The appearance of the superconductivity crucially depends on the perfectness of the vacancy order [3]. The magnetic and vacancy orders in superconducting (Tl,Rb)2Fe4Se5 (245) single-crystals were investigated using high-pressure neutron diffraction technique [4]. Similar to the temperature effect, the block antiferromagnetic order gradually decreases upon increasing pressure while the Fe vacancy superstructural order remains intact before its precipitous drop at the critical pressure Pc =8.3 Gpa. Combining with previously determined Pc for superconductivity, our phase diagram under pressure reveals an intimate connection among the block antiferromagnetic order, the Fe vacancy order and superconductivity for the 245 superconductor.

[1] W. Bao, Q. Huang, G-F. Chen et al., Chin. Phys. Lett. 28, 086104 (2011).
[2] F. Ye, S. Chi, W. Bao et al. Phys. Rev. Lett. 107, 137003 (2011).
[3] W. Bao, G-N Li, Q. Huang et al., Chin. Phys. Lett. 30, 027402 (2013).
[4] F. Ye, W. Bao, S. Chi et al., arXiv:1405.4020 (2014).
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Aug 18
Monday

Heterogenous Processing of Imaging Data Sets for High-throughout, Single Cell Characterization

Speaker: Dr. David Kissick, Univ. of Illinois at Urbana-Champaign
XSD Presentation
436/C010 @ 11:00 AM
View Description
Cell-to-cell variability and functional heterogeneity are integral features of multicellular organisms. Assays to elucidate these vital chemical variations are best performed with single cell samples because tissue homogenates average the biochemical composition of many cells and oftentimes include extracellular components. Numerous single cell microanalysis techniques have been developed, but many rely on molecular probes that often produce limited throughput or information. Mass spectrometry (MS) is an untargeted, multiplexed and sensitive analytical method that is well-suited for studying chemically complex single cells that have low analyte content. In this work, both Aplysia californica neurons and rat pituitary cells have beenare analyzed using optical microscopy-guided matrix-assisted laser desorption / ionization time-of-flight (MALDI-TOF) MS. The cells are dispersed onto a microscope slide to generate a sample where potentially hundreds to thousands of cells are separately located. Optical imaging is used to determine the cell coordinates on the slide, and the locations are used to automate MS analysis to each cell. While larger neurons can be directly localized, for the pituitary cells, the cells were labeled with a nuclear dye and dispersed onto a microscope slide, generating a sample where hundreds to thousands of cells were separately via fluorescent imaging to determine the cell coordinates on the slide, with the locations used to automate the MS analysis specifically to target each cell. The assay yielded a large amount of data, which was statistically analyzed using a heterogeneous computing module that parallelizes calculations to reduce processing time. For the pituitary cells, principal component analysis (PCA) was also applied to several thousand cells, with the results highlighting distinct cell types such as melanotrophs, originating from functionally different pituitary regions of the pituitary. Rare cells within the population were also found using a modified PCA method that focuses on signals described by the lower principal components. We demonstrate that the single cell MALDI-TOF MS approach described here can be used to achieve high-throughput analyses of cellular populations.
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Aug 15
Friday

User Science Seminar

APS Seminar
401/A1100 @ 12:00 PM
Aug 14
Thursday

Direct and sequential multi-photon ionization of rare-gas atoms in the XUV

Speaker: Tommaso Mazza, European X-Ray Free Electron Laser Facility GmbH
XSD Seminar
401/A1100 @ 11:00 AM
View Description
The interaction of individual atoms with intense short-wavelength radiation is a fundamental issue in particular for atomic physics, but also in general for many other areas of FEL-based science. To understand the ionization dynamics and the role of sequential and direct multi-photon absorption processes, relevant information can be obtained experimentally from both ion and electron spectroscopy, supported by theoretical approaches. In this report the results of a broad investigation are presented, performed at different XUV photon energies delivered by the Free electron LASer in Hamburg (FLASH), on systems with electronic structures of different complexities (Ar and Xe atoms). At first, unexpectedly high charge states are reported for Argon at different photon energies. The comparison of the intensity dependent ion yield spectra with the results of rate equation calculations reveals the importance of excited states during the different steps of the ionization ladder. In addition, electron spectroscopy is used in combination to ab-initio calculations to provide a quantitative insight into the relevance of direct multi-photon absorption in the ionization process. The more complex and intriguing case of Xe shows, in contrast to the case of Ar, a more pronounced and photon energy dependent production of highly charged ions. The role of collective electronic response in the multiphoton ionization will be discussed considering the one photon and two-photon direct 4d electron emissions with respect to their dependence on the photon energy tuning in the region of the 4d->εf giant resonance.
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Aug 13
Wednesday

Bonding of Copper and Glidcop to Stainless Steel - New Applications for Known Techniques

Speaker: Bran Brajuskovic, AES / MED Group
AES Seminar
401/B3100 @ 10:00 AM
Aug 12
Tuesday

The Physics Endstation at the High Energy Beamline P07 at PETRA III

Speaker: Uta Rütt, Petra III Synchrotron, DESY
XSD Presentation
431/C010 @ 2:00 PM
View Description
The high energy materials science beamline at PETRA III (P07) is designed to cover photon energies from 50 to 200 keV. This beamline is jointly operated by Helmholtz Centre Geesthacht (2/3) and DESY (1/3), which is responsible for a triple axis diffractomer in the physics endstation. The instrument is designed for a broad variety of diffraction experiments covering scattering on surfaces as well as powder diffraction up to single crystal crystallography in different sample environments. The instrument is equipped with a sample stage for High Energy Micro Diffraction (HEMD), which allows highly precise positioning of the sample in real and angular space. In addition an Eulerian cradle is available to be mounted for crystallographic work on single crystals. For heavy components, like magnet cryostats, a different sample stage can be mounted in parallel to the HEMD sample stage. It´s able to carry components up to 350 kg. The beam can be focused by compound refractive lenses down to 2 μm x 40 μm at the sample position. For fast experiments with less resolution the setup behind the sample can easily be switched to a flat panel detector placed on the same stage as the point detector with analyzer. The detector to sample distance can be varied during the experiment between 0.5 and 3.5 m. Examples of the latest experiments will be presented and discussed.
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Aug 12
Tuesday

FTIR Spectral Micro-Tomography in Full Color

Speaker: C.J. Hirschmugl, University of Wisconsin-Milwaukee
XSD Presentation
401/A1100 @ 10:00 AM
View Description
The holy grail of chemical imaging is to provide spatially and temporally resolved information about heterogeneous samples on relevant scales. Synchrotron-based Fourier Transform infrared imaging1 combines rapid, non-destructive chemical detection with morphology at the micrometer scale, to provide value added results to standard analytical methods. Hyperspectral cubes of (x,y, z, Abs (l)) are obtained employing spectromicrotomography2, a label free approach, it inherently evaluates a broad array of wide organic materials, with minimal sample preparation and modification. Examples presented here (polymer composites, single cells and colonies of cells) demonstrate the broad applicability of this approach to detect complex chemical information of intact samples.
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Aug 8
Friday

User Science Seminar

APS Seminar
401/A1100 @ 12:00 PM
Aug 8
Friday

Flexural Nanopositioning Stages Design for Synchrotron Radiation Applications at the APS

Speaker: Deming Shu, APS-AES
ASD Seminar
401/A1100 @ 9:00 AM
View Description
With brighter upgraded APS x-ray sources and more advanced x-ray optics, scientists at the APS will need more customized novel instruments. Nanopositioning techniques present a significant opportunity to support the state-of-the-art synchrotron radiation instrumentation research at the APS upgrade project. This seminar summarizes the design and development of flexural nanopositioning stages for synchrotron radiation applications at the APS. It includes:

  • Stages design for Argonne CNM hard x-ray nanoprobe at the APS;
  • Stages design for APS high-energy-resolution monochromators and analysers;
  • Monochromator stages design for SLAC/LCLS beamlines and self-seeding project, as well as Argonne WFO project for European-XFEL.

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Aug 6
Wednesday

Directed Self-Assembly of Block Copolymers: A Platform for Nanomanufacturing

Speaker: Paul F. Nealey, University of Chicago and Argonne National Laboratory
APS Colloquium
402/AUD @ 3:00 PM
Aug 5
Tuesday

The Sirius Project

Speaker: Harry Westfahl, Jr., Brazilian Synchrotron Light Laboratory, Campinas, Brazil
XSD Seminar
401/A1100 @ 11:00 AM
View Description
The Brazilian Synchrotron Light Laboratory has started the construction of Sirius, a 3 GeV and 0.28 nm rad emittance storage ring. In this talk I will present some of the main aspects of this new storage ring and its first and second phase beamlines, as well as the current status of the project.
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Aug 1
Friday

User Science Seminar

APS Seminar
401/A1100 @ 12:00 PM
Aug 1
Friday

In situ x-ray diffraction applied to the study of metal oxide and carbide catalysts

Speaker: Wenqian Xu
XSD Seminar
Advanced Photon Source, Argonne, IL
401/A1100 @ 11:00 AM
View Description
In situ x-ray diffraction (XRD) is nowadays widely applied in physical science to study material structures under desired conditions. In the field of catalysis, it is of key interest to know how a catalyst functions and how its structure related to its catalytic property. Probing the catalyst with x-ray at its working state is helpful in providing such information. In this talk, two studies are presented. In the first one, a Ni/CeO2 catalyst for ethanol steam reforming (ESR) is investigated with both in situ XRD and in situ infrared spectroscopy. Ethoxyl, acetate, carbonate and hydroxyl species are identified as surface intermediates that appear during the reaction process. The synergy between metallic Ni and the CeO2 support is revealed. The second study is on carburization of molybdenum oxide by temperature-programmed reduction in hydrocarbons. Formation of either the cubic or the hexagonal carbide phase is found to be affected by both concentration and speciation of the hydrocarbons as well as the heating procedures. Close examination of the XRD and the pair distribution function (PDF) profile of the cubic carbide phase shows the presence of stacking faults in its structure.
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Aug 1
Friday

Nanofabrication of Diffractive X-ray Optics for Applications at Synchrotrons and XFELs

Speaker: Christian David, Paul Scherrer Institut, Villigen, Switzerland
XSD Seminar
438/C010 @ 10:00 AM
View Description
I present recent developments in nanolithography to produce diffractive x-ray optics, and experimental results obtained with these devices. For the use at synchrotrons we at PSI have developed a new generation of Fresnel zone plates produced by a line doubling approach. Used in a scanning microscope, these lenses can resolve features down to 9 nm in the soft x-ray range and down to 15 nm in the multi keV range. To improve the efficiency for hard x-rays, a fabrication strategy was developed to produce two stacked zone plate structures on both sides of the support membrane. A diffraction of close to 10% was obtained at 9 keV photon energy for a zone plate with 30 nm zone width. A similar technique can be applied to produce blazed zone plates with diffraction efficiencies of 50% providing 100 nm spot size.

For use at x-ray free-electron laser (XFEL) sources, diffractive optics must be capable of withstanding extreme radiation loads. We show how diffractive optics made of diamond can be used for various applications including nanofocusing, beam-splitting, spectral monitoring and ultrafast time resolved studies
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Jul 25
Friday

User Science Seminar

APS Seminar
401/A1100 @ 12:00 PM
Jul 24
Thursday

Japanese Activity in Industry-Academia Cooperation Towards ILC

Speaker: Masanori Matsuoka, Mitsubishi Heavy Industries, Ltd.
APS Seminar
360/A-224 @ 3:00 PM
View Description
The advanced accelerator association promoting science and technology (AAA) was established in June 2008 to study how to reach a consensus to realize ILC in Japan. We promote and seek various industrial applications of advanced accelerators and technologies derived from R&D on accelerators. Our activities facilitating an active industry-government-academia collaboration will be presented.
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Jul 24
Thursday

Improved Performance of the Vortex Silicon Drift Detector

Speaker: Shaul Barkan, Hitachi High-Technologies Science America, INC.
APS Seminar
Advanced Protein Crystallization Facility
446/AUD @ 1:00 PM
View Description
We have improved the resolution, high count-rate performance and quantum efficiency (QE) of the Vortex silicon drift detector (SDD) by integrating it with new front-end electronics and by increasing the thickness from 0.5 mm to 1.0 mm. A series of tests indicates excellent results: a QE that matches theoretical values and enhancement of the throughput at practical dead time (DT) operation. An output count rate of 1.6 Mcps at 2.0 Mcps input count rate (20% DT) using the “Quantum Detectors” Xpress3 processor is achieved with an energy resolution of ~200 eV.
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Jul 18
Friday

User Science Seminar

APS Seminar
401/A1100 @ 12:00 PM
Jul 16
Wednesday

Polyhedral Crystalline Membranes

Speaker: Monica Olvera de la Cruz, Northwestern University
APS Colloquium
402/AUD @ 3:00 PM
Jul 16
Wednesday

Reconstructing Diet in Fossil Humans: How Synchrotrons Can Help

Speaker: Callum Ross, University of Chicago
XSD Presentation
431/C010 @ 11:00 AM
View Description
Changes in human diet have had a profound influence on the design (form-function relationships) of the human feeding system. Dental design is not only important because it is sensitive to both changes in the material properties of food and feeding behavior, but also because teeth are well represented in the fossil record. I will review recent work on the evolution of feeding system design in primates, with special emphasis on fossil humans, and discuss the roles of synchrotron-based measurement of enamel micro-structure and finite element modeling of dental form for understanding the evolution of human feeding systems.
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Jul 11
Friday

New Techniques for Probing and Controlling Nonadiabatic Molecular Dynamics

Speaker: Vladimir S. Petrovic, Stanford University, PULSE Institute for Ultrafast Energy Science
XSD Presentation
401/A1100 @ 2:00 PM
View Description
On the molecular level the conversion of energy from one form to another occurs via nonadiabatic interactions that govern the exchange of energy between different degrees of freedom. Often this exchange occurs on fast timescales, which makes time-resolved pump-probe techniques suitable for studying it. In the first part of the talk I will report on using time-resolved dissociative ionization to probe structural changes that result from nonadiabatic interactions. This technique relies on the characterization of the dissociation-formed fragments, their correlations, or their coincidences. I will discuss complementary methods of initiating dissociative ionization via weak-field x-ray absorption or strong-field IR absorption for investigation of nonadiabatic processes that lead to unimolecular isomerizations in small hydrocarbons. In particular, dynamics at conical intersections can be studied and controlled using short-pulse x-ray and intense IR radiation. In addition, I will discuss more recent experiments performed at Linac Coherent Light Source that investigate ultrafast x-ray initiated molecular dynamics. In the second part of the talk I will talk about plans to extend the application of these techniques to more complex multi-electron and aqueous systems. These experiments seek to generate insight relevant for optimizing conditions for diffraction-before-destruction techniques in biologically relevant systems.
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Jul 11
Friday

User Science Seminar

APS Seminar
401/A1100 @ 12:00 PM
Jul 11
Friday

Current Status of the APS Linac and SR/Booster Klystron High-Voltage Power Supplies and the 352-MHz RFTS

Speaker: Gian Trento, ASD-RF
ASD Seminar
401/A1100 @ 9:30 AM
View Description
The present Radio Frequency (RF) Group machine operation goals are to help maintain APS mean time between faults at 100 hours or better and maintain injector, storage ring (SR), and x-ray production availability at 97% or better. To continue to meet these goals, an aggressive approach was instigated to combat parts obsolescence and aging of the accelerator systems. The latest improvements to the linac and SR/booster klystron high-voltage power supplies will be discussed. The APS 352-MHz RF Test Stand (RFTS) was constructed to test and condition booster and SR rf cavity components. The adaptation of a pulsed rf conditioning method was introduced and tested. This methodology and performance of the RFTS will be discussed.
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Jul 10
Thursday

Colossal Magneto-resistant Materials: The key role of phase separation

Speaker: M. Baldini, HPSynC Carnegie Institution of Washington
XSD Presentation
401/A1100 @ 11:00 AM
Jul 9
Wednesday

MOSFET-based Inductive Adder for On-axial Injection Strip-line Kicker

Speaker: Dr. Jinhui Chen, Accelerator Research Center, IHEP, CAS, Beijing, China
ASD Seminar
401/B4100 @ 11:00 AM
View Description
A Low emittance ring with limited dynamic aperture needs ultra-fast kickers for an on-axial injection system. A set of short 2-electrode strip-line kickers driven independently by bipolar HV ultra-fast pulsed power supplies are able to meet the on-axial injection requirements.

MOSFET-based inductive adder is one of the potential approaches for a HV ns-fast pulser. Power MOSFETs are the fastest regular commercial semiconductor switches and can turn on in 1-2 ns with an appropriate driver. Inductive adders are one of pulsed power superposition topologies. A compact coaxial transformer structure is the key to a fast inductive adder.

An inductive adder prototype with 10 ns FWHM 5kV into 50Ω was developed at IHEP and a higher voltage adder design is under consideration. In the meantime, we are focusing on DSRD-based transmission-line modulator technology which has amazing performance compared with MOSFET-based inductive adders.
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Jul 3
Thursday

New Tools and New Insights Into Bioinorganic Chemistry

Speaker: Simon James, Australia Synchrotron
XSD Presentation
438/C010 @ 2:00 PM
View Description
Transition metals imbibe biology with impressive catalytic flexibility and serve as stabilizing structural foundations for the macromolecules of the cell. Coordination chemistry defines the biological utility of transition metals but remains under studied due to a lack of suitable probes. To be useful, such probes must meet a number of demanding challenges, including minimal preparation requirements, extremely high sensitivity, high spatial resolution, and minimal disturbance to both elemental distribution and chemical speciation. When used alongside protocols which limit preparation artefacts, these requirements are satisfied by the combination of scanning X-ray fluorescence microscopy (sensitivity and spatial resolution) and X-ray Absorption Near Edge Structure (XANES; to determine speciation). In the past such an approach was prohibitively time consuming but recent developments in energy-dispersive detector technology have enabled a step change in efficiency of previously limiting parameters such as sensitivity and speed. These gains have been exploited to develop 2- and 3-dimensional scanning X-ray fluorescence XANES and used to map the native metalloarchitecture throughout intact multi-cellular organisms. The development of these techniques for visualizing the 3-dimensional distribution of coordination sites within intact whole animals promises to provide key insights into cell function and bioinorganic chemistry driving health and disease.
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Jun 30
Monday

ICMS Upgrade Orientation

APS Presentation
401/A1100 @ 10:00 AM
View Description
A new version of the ICMS is going to be put in place over the weekend of July 4. Every effort is being made to keep the appearance the same, to ensure that the system works the same for users and to preserve all the documents and information which exist in the current ICMS. There are some minor changes, the purpose of this session is to explain these changes to all parties who wish to know in advance.

The session will be held at 10am on Monday, June 30 in Room A1100. The presentation should take less than 30 minutes and we will be available for questions afterward.

The same information that will be presented is available in a document in the ICMS. Its id is APS_1445875 and a pdf is located here (ICMS login required):

https://icmsdocs.aps.anl.gov/docs/groups/aps/documents/manual/aps_1445875.pdf
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Jun 27
Friday

User Science Seminar

APS Seminar
438/C010 @ 12:00 PM
View Description
Speakers for June 27:

1) Johan van Lierop,
Dept. of Physcis, University of Manitoba, "Curious Interplay Between Core and Shell Transition metal Oxide Nanoparticles"

2) Paul Fenter
Chemical Sciences & Engineering, ANL "Structural Origins of Potential Dependent Hysteresis at the Electrified Graphene/Ionic Liquid Interface"

Lunches will be available from the 401 Grill, located on the lower level of Bldg. 401, just below A1100. The Grill is open from 11:00 a.m. to 2:00 p.m. Please view the menu at:

http://www.aps.anl.gov/Guest_House/Dining/401_Grill/menu.htm
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Jun 20
Friday

User Science Seminar

APS Seminar
438/C010 @ 12:00 PM
Jun 17
Tuesday

Resonant Soft X-ray Scattering for Soft Materials

Speaker: Dr. Cheng Wang, Advanced Light Source, Lawrence Berkeley National Laboratory
XSD Presentation
401/E1100 @ 10:00 AM
View Description
To meet the challenge of investigating new and complex materials that are relevant to mesoscale energy science, it is essential to connect microscopic dynamical processes to activated kinetic processes and macroscopic function in diverse soft and hard materials. We need sharper tools in order to discover, understand, and control mesoscale phenomena and architectures. Over the past a few years, we have developed Resonant Soft X-ray Scattering (RSoXS) and constructed the first dedicated resonant soft x-ray scattering beamline at the Advanced Light Source, LBNL. RSoXS combines soft x-ray spectroscopy with x-ray scattering thus offers statistical information for 3D chemical morphology over a large length scale range from nanometers to micrometers. Using RSoXS to characterize multi-length scale soft materials with heterogeous chemical structures, we have demonstrated that soft x-ray scattering is a unique complementary technique to conventional hard x-ray and neutron scattering. Its unique chemical sensitivity, large accessible size scale, molecular bond orientation sensitivity with polarized x-rays and high coherence have shown great potential for chemical/morphological structure characterization for many classes of materials. Some recent development of in situ soft x-ray scattering with in-vacuum sample environment will be discussed. In order to study sciences in naturally occurring conditions, we need to overcome the sample limitations set by the low penetration depth of soft x-rays and requirement of high vacuum. Adapting to the evolving environmental cell designs utilized increasingly in the Electron Microscopy community, customized designed liquid/gas environmental cells will enable soft x-ray scattering experiments on biological, electro-chemical, self-assembly, and hierarchical functional systems in both static and dynamic fashion. Initial RSoXS results of solar fuel membrane assembly/fuel-cell membrane structure in wet cell will be presented.
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Jun 14
Saturday

National School on Neutron and X-ray Scattering

APS Course
Argonne National Laboratory/Oak Ridge National Laboratory
Jun 13
Friday

User Science Seminar

APS Seminar
401/A1100 @ 12:00 PM
Jun 9
Monday

Maia Driven X-ray Fluorescence Imaging: Capturing Challenging Detail in Natural Samples

Speaker: Chris Ryan, CSIRO Earth Science and Resource Engineering
APS Presentation
431/C010 @ 11:00 AM
View Description
Capturing exquisite fine detail in scanning fluorescence X-ray microscopy on a wide range of spatial scales in many natural materials has motivated the development of the Maia detector system and its integrated FPGA based real-time processor. Using a large detector array and an event-by-event acquisition mode to eliminate readout overheads enables transit time per pixel down to the microsecond scale and pixel or voxel count exceeding 100M. Real-time spectral deconvolution in the FPGA enables real-time display of deconvoluted element images to users to help guide the experiment. This talk will provide an update on recent Maia developments and applications at the Australian Synchrotron including the location and depth mapping of rare precious metal phases in mantle rocks.
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Jun 6
Friday

User Science Seminar

APS Seminar
401/A1100 @ 12:00 PM
Jun 2
Monday

Evolution of Wakefield Excitation in a Dielectric Waveguide by a Sequence of Relativistic Electron Bunches

Speaker: Prof. Ivan Onishchenko, Ukraine KIPT
APS Seminar
360/A224 @ 3:00 PM
View Description
The results of theoretical and experimental studies of wakefield excitation in a dielectric waveguide of a finite length by a long sequence of relativistic electron bunches have been carried out. They reveal the possibility of wakefield amplitude enhancement at summing coherent fields of separate bunches when the bunch repetition frequency coincides with the excited field frequency. It has been theoretically shown that the number of bunches whose wakefields give growth of the total wakefield amplitude is restricted and depends on values of waveguide length and the group velocity of excited wave. For experimental verification of this result, a facility has been created in which a long sequence of electron bunches produced by linear resonant accelerator has been used to excite the wakefield in dielectric waveguides of various lengths. In accordance with the theory, the stepwise increased dependence of the wakefield amplitude upon the dielectric waveguide length has been obtained. Such behavior of the dependence gives evidence of the coherent wakefield gain from each bunch determined by the above number.
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May 23
Friday

Experimental Calibration of Rectangular Gradient Bending Magnet Models

Speaker: Kent Wootton, University of Melbourne and Australian Synchrotron
APS Seminar
401/B2100 @ 2:30 PM
View Description
Modern storage ring light sources are designed and constructed with a strategy to minimize the horizontal emittance. Towards this goal, rectangular bending magnets with a defocusing gradient are used in the storage ring lattices of the 3 GeV Australian Synchrotron and SPEAR3 storage rings.

We have performed measurements that confirm our approach to modeling these rectangular gradient magnets. Resonant spin depolarization was used at both rings as a precision beam energy measurement.

We find that numerical evaluation of the trajectory is a better description than the usual hyperbolic cosine trajectory through the bending magnet. This numerical modeling approach could be directly useful to the design of future storage rings.
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May 22
Thursday

Virtualization and Cloud Computing for Scientific Applications

Speaker: Kate Keahey, Mathematics and Computer Science Division, Argonne National Laboratory
APS Seminar
401/A5000 @ 2:00 PM
May 22
Thursday

The Power and Flexibility of X-Ray Scattering as a Probe of Magnetic Systems: KCuF3 and Fe/Gd Thin Films

Speaker: James C. T. Lee, Advanced Light Source, LBNL
XSD Presentation
431/C010 @ 10:00 AM
View Description
X-ray scattering is an excellent tool for studying both the crystal structure and, via resonant scattering, the electronic structure of the magnetic state. To illustrate the power and flexibility of x-rays as a probe, I will discuss magnetism in orbitally ordered KCuF3 single crystals and Fe/Gd thin films exhibiting perpendicular anisotropy.

Due to its simplicity, KCuF3 is the ideal system of orbital physics, which plays an integral part in many exotic phenomena like colossal magnetoresistance. The basis for nearly all theories of orbital physics Kugel–Khomskii model, being the first to explain the symmetry of orbital and magnetic order in KCuF3. However, no refinement of the Kugel-Khomskii model heretofore could account for other prominent features of KCuF3, such as the disparity of its orbital and spin ordering energy scales. Based on x-ray scattering (done in part at Sector 4ID-D, APS) and Raman scattering experiments, we have found that the missing piece of the puzzle is a direct orbital exchange interaction. This mechanism may play a crucial role in other orbitally active materials. Unlike KCuF3, the magnetic order in Fe/Gd thin films exists over mesoscopic scales. These systems display complex domain structures and phase diagrams. Judiciously made films with large perpendicular anisotropy may show novel domain structures and spin textures. Resonant soft x-ray scattering (RSXS) at the Fe L3 and Gd M5 edges was performed at Beamline 12.0.2.2, ALS, to probe the domain structure with evolving applied magnetic field and sample temperature. Ordered arrays of stripe domains appear well below saturation. As the applied magnetic field increases, a metamagnetic transition occurs and the stripe array smoothly transforms into a hexagonal bubble lattice. The bubble domains may display a skyrmionic spin texture.

Not just limited to single crystals and thin films, RSXS is also an ideal tool for studying lithographically made systems engineered to display exotic magnetism (e.g. nanodot arrays displaying spin ice behavior). The power of RSXS can also be deepened by using x-ray photon correlation spectroscopy to characterize the dynamics of magnetic materials. Such demonstrations of the flexibility and power of x-ray scattering will be made at the new RSXS end station at Sector 29.
[ Hide ]
May 21
Wednesday

Electronic Transitions, Coherence, and Hybridization: A Spectroscopic Study of Unusual Electronic Properties in Strongly Correlated Materials

Speaker: Fanny Rodolakis Simoes, University of Illinois-Chicago
XSD Presentation
431/C010 @ 11:00 AM
View Description
Understanding phase transition induced by strong electronic correlations represents one of the major challenges in condensed matter physics. Phenomena presenting great interest both from point of view of basic science and of their potential technological applications, like metal-insulator transitions and high temperature superconductivity, are typical examples of effects determined by collective electronic excitations. On the theoretical side, development of Dynamical Mean Field Theory provided a powerful conceptual approach to interpret these phenomena. On the experimental side, one of the main challenges for the study of strongly correlated materials is the development of techniques giving access to the electronic structure of these systems while tuning external parameters (temperature, pressure, electric field, etc.) across their often complicated thermodynamic phase diagrams.

In this talk I will present an investigation of some of the most remarkable manifestations of strong correlations in materials by using different spectroscopic techniques such as high-resolution X-ray absorption (PFY-XAS) and angular resolved photoemission spectroscopy (ARPES): the metal-insulator transition in the transition metal oxide (V1-xCrx)2O3, the Kondo effect in the heavy fermion compound Ce2RhIn8, and high Tc superconductivity in copper oxide Bi2Sr2CaCu2O8+δ. By shedding the light on their electronic structures, those measurements combined with LDA+DMFT calculation reveal an even more intricate behavior like the inequivalence of temperature, doping and pressure in the vanadium sesquioxide phase diagram, or multiple energy scales in Ce2RhIn8.
[ Hide ]
May 20
Tuesday

Correlating Interfacial and Bulk Nanostructure with Performance of Organic Electronic Devices: The Usefulness of Soft X rays

Speaker: Hongping Yan, High-Pressure Collaborative Access Team (HP-CAT), Geophysical Laboratory, Carnegie Institution of Washington
XSD Presentation
431/C010 @ 10:00 AM
View Description
Soft matter systems often consist of multiple components and are naturally or synthetically nanostructured for optimal properties and performance. Near an absorption edge (e.g. carbon 1s), the high energy-dependence of absorption coefficient and index of refraction provides tunable contrast between functional moieties of polymer thin films for improved soft x-ray scattering and reflectivity characterization capability.

In this presentation, the usefulness of resonant soft x-ray reflectivity (R-SoXR) and scattering (R-SoXS) in revealing interfacial width and bulk nanomorphology of organic electronics, including organic solar cells and organic field effect transistors, are demonstrated with corresponding study cases. The morphology characterizations are correlated to device performance for better understanding the impact of processing method on nanomorphology and hence the performance of these organic electronic devices. A practical and accurate method to obtain the complex index of refraction, especially the decrement δ, accross the carbon 1s absorption edge is demonstrated, which is expected to greatly improve the simulation and interpretation of R-SoXR and R-SoXS data.
[ Hide ]
May 16
Friday

COMSOL Multiphysics Molecular Flow & Heat Transfer Seminar

Speaker: James Ransley and Mian Qin, COMSOL
AES Seminar
401/A1100 @ 10:00 AM
View Description
This seminar offers a live demonstration of the COMSOL Multiphysics modeling environment and the unique opportunity to work with molecular flow & heat transfer applications. This is the perfect occasion to ask questions and participate in the modeling process. No prior experience is needed. All attendees will receive a free 2-week trial.

Details & Registration: http://www.comsol.com/events/cm44w/30479/
[ Hide ]
May 7
Wednesday

Laser Particle Acceleration with Femtosecond PW Lasers

Speaker: Chang Hee Nam, Institute for Basic Energy Science and Gwangju Institute of Science and Technology
APS Seminar
401/B2100 @ 3:30 PM
View Description
The research on laser-matter interactions has entered a new era in the relativistic regime thanks to the recent rapid progress in ultrashort high-power laser technology. High-power femtosecond lasers, producing outputs of 1 PW and 1.5 PW at 30 fs from two beamlines, have been developed at GIST. Using this PW laser facility, the Center for Relativistic Laser Science (CoReLS), a research center of Institute for Basic Science (IBS), works on experimental and theoretical investigations of relativistic laser-matter interactions. Using the PW laser we succeeded in generating multi-GeV electrons through two stages of amplification and in producing protons with energy of 45 MeV. Further improvements in laser particle acceleration have been achieved by controlling experimental parameters such as spectral phase, polarization, and target geometry. Ultra-intense laser pulses, as the primary source, or short-wavelength radiation and relativistic charged particles, as the secondary source, can expose matter under extreme conditions. The exploration of such extreme physical conditions will bring new outcomes in fundamental physics of laser-matter interactions.
[ Hide ]
May 6
Tuesday

A Look at ParaView for 3D Data Visualization

Speaker: Joe Insley, Mathematics and Computer Science Division, Argonne National Laboratory
APS Seminar
431/C010 @ 3:00 PM
May 6
Tuesday

The Xraylib Software Package for X-ray Science Applications

Speaker: Tom Schoonjans, University of Sassari, Italy
APS Seminar
431/C010 @ 9:30 AM
Apr 18
Friday

User Science Seminar

APS Seminar
401/A1100 @ 12:00 PM
Apr 16
Wednesday

APS/Users Operations Monthly Meeting

APS Meeting
402/AUD @ 2:30 PM
Apr 16
Wednesday

Sensors and Systems for Digital Radiography

Speaker: Vivek V. Nagarkar, RMD Inc.
XSD Presentation
401/A1100 @ 1:30 PM
View Description
At RMD we have developed modular digital imaging detectors for applications ranging from hypervelocity projectile tracking and ballistic impact analysis to medical X-ray CT and time-resolved diffraction studies. These systems benefit from recently discovered binary and ternary phase inorganic scintillators and novel ceramic scintillators that demonstrate unprecedented emission efficiencies (70,000 to 100,000 ph/MeV), high densities (5 to 9 g/cc), high effective atomic numbers (Z~50 to 70), and radiate in 450 to 650 nm range with fast decay. These recently discovered scintillators are being fabricated at RMD for use in digital radiography by novel processes like physical vapor deposition (PVD) or laser processing. Our advanced PVD techniques results in the formation of structured scintillators in microcolumnar and/or macrocolumnar format, while our laser processing techniques using solid state laser are capable of forming structured scintillators of arbitrary shapes.

Here we will present novel scintillators fabricated in microcolumnar or pixelated form that minimize the traditional tradeoff between spatial resolution and detector efficiency and are suitable for imaging low (8 keV) to high (450 kVp) energy X-rays and/or thermal neutrons. Performance characteristics of radiographic imaging detectors and systems will also be discussed.
[ Hide ]
Apr 16
Wednesday

The High Energy Density Science Instrument at European XFEL: Application and Status

Speaker: Thomas Tschentscher, European XFEL
APS Presentation
401/A1100 @ 11:00 AM
View Description
The High Energy Density science (HED) instrument at the European XFEL will provide unique possibilities for the investigation of near solid density matter at states of extreme excitation. European XFEL is a large research infrastructure currently under construction in the Hamburg metropol region, North Germany. It will provide researchers with free-electron laser radiation in the x-ray range from 0.25 to 25 keV and six initial science instruments dedicated to a variety of x-ray techniques and applications. First experiments are scheduled for 2016. At the HED instrument intense, coherent, and ultrashort x-ray pulses can be applied to obtain structural and electronic properties of highly excited condensed matter in extreme conditions. Excitations will be driven using a variety of optical laser systems. Also pulsed magnetic and electric fields are considered. In addition, the intense FEL pulses can be used for excitation, too. The major science areas addressed by the HED instrument are condensed matter at extreme excitation, solid density plasmas and quantum states of matter.

The talk will provide an update on the status of European XFEL, the HED instrument design and describe the scientific applications to be carried out at the HED instrument.
[ Hide ]
Apr 15
Tuesday

Exchange Email Service Town Hall Meeting

Speaker: CIS
APS Meeting
401/A1100 @ 3:00 PM
View Description
CIS will be hosting an Exchange Email Service Town Hall meeting on Tuesday April 15, from 3:00-4:00 pm in room A1100. We are holding this meeting to provide information around the migration to Exchange, lessons learned during the migration, and to allow APS users of the system a chance to provide feedback on the email and calendar service.
[ Hide ]
Apr 11
Friday

User Science Seminar

APS Seminar
401/A1100 @ 7:42 AM
Apr 4
Friday

User Science Seminar

APS Seminar
401/A1100 @ 12:00 PM
Apr 3
Thursday

Liquid Nitrogen Storage Tank Replacement Planning Meeting

APS Meeting
401/A1100 @ 1:00 PM
View Description
During the upcoming April-May maintenance shutdown, the storage tanks for modules B and C (Sector 10 through 27) of the Liquid Nitrogen Distribution System (LNDS) will be replace with new larger tanks.

The tanks will be a significant improvement to the LNDS; increasing the reliability of the LN2 supply to our beamlines.

There are potential risks for ALL the beamlines, not just for the Sector 10-27 beamlines that are directly effected. User input is desired.
[ Hide ]
Apr 2
Wednesday

Exploring the Physical Properties of Matter in Extreme Conditions

Speaker: Siegfried H. Glenzer, SLAC National Accelerator Laboratory
APS Colloquium
402/AUD @ 3:00 PM
Mar 31
Monday

MAX IV Magnet Design and Storage Ring Magnet Status

Speaker: Martin Johansson, MAX IV Laboratory
APS Upgrade Seminar
401/A1100 @ 1:30 PM
View Description
Martin will present a general introduction to the MAX IV magnet block design concept. He will also present the current production status, specific field measurement results and alignment of magnet elements within magnet blocks.

Following the talks Martin will be available for a question and answer session until 4:00 PM.
[ Hide ]
Mar 27
Thursday

Optimum Performance of the Novel Accelerator for Iterative Phase Retrieval in the Fresnel Region Applied to X-ray Phase Contrast Imaging

Speaker: Nghia Vo, Diamond Light Source
XSD Presentation
431/C010 @ 3:00 PM
View Description
Iterative phase retrieval in the Fresnel region based on Gerchberg-Saxton algorithm suffers from slow convergence and stagnation. Recently, a novel accelerator, named random signed feedback (RSF), was proposed (http://dx.doi.org/10.1063/1.4769046) which shows a superior performance compared with other traditional techniques: hybrid input output (HIO) and conjugate gradient search (CGS). Its feasibility is confirmed by applying on X-ray phase contrast tomographic data, collected at beamline I12 Diamond Light Source, which shows promising results. In this talk, I will present how I investigated the RSF accelerator under various conditions to obtain its optimum performance.
[ Hide ]
Mar 27
Thursday

X-ray Diffraction from Perfect Crystals - the 100th Anniversary of the First Calculations by C.G. Darwin

Speaker: Denny Mills, Advanced Photon Source
XSD Presentation
401/A1100 @ 11:00 AM
View Description
In 1914, C. G. Darwin published two papers* that established some of the basic features of x-ray diffraction in perfect crystals. One of those features was near-unity reflectivity over a narrow angular range at the Bragg condition, a phenomenon that is still known as the “Darwin width” of the reflection. The talk will briefly describe his calculational approach to scattering in perfect crystals, impact of those calculations, and other aspects of Darwin’s life and work.

*"The Theory of X-ray Reflexion", by C. G. Darwin, Philosophical Magazine, 27, (1914), p313-333 and “The Theory of X-ray Reflexion Part II”, by C. G. Darwin, Philosophical Magazine, 27, (1914), p675-690.
[ Hide ]
Mar 26
Wednesday

APS/Users Operations Monthly Meeting

APS Meeting
402/AUD @ 9:30 AM
Mar 21
Friday

Hybrid Pixel Array Detectors Enabling New Science

Speaker: Clemens Schulze-Briese, Dectris Ltd.
XSD Presentation
401/A1100 @ 2:00 PM
View Description
PILATUS single photon counting Hybrid Pixel Device (HPD) detectors have transformed synchrotron research by enabling new data acquisition modes and even novel experiments. At the same time data quality has improved due to noise-free operation and direct conversion of the X-rays. Millisecond readout times and high-frame rates allow for hitherto unknown speed and efficiency of data acquisition.

At cryogenic temperatures, PILATUS allows to acquire data of optimal quality by collecting high multiplicity data at low dose rate, referred to as dose slicing. Monitoring data quality indicators as a function of frame number reveals the optimal data quality for a given crystal. This overcomes the problem of traditional data collection, where radiation damage may affect data accuracy before a complete data set is collected. In contrast, dose-sliced data collection always enables the exploration of the full diffraction potential of the crystal. The noise-free counting of PILATUS detectors allows the dose per frame to be reduced without loss of data accuracy due to read-out noise. Furthermore, high frame rates enable acquisition of optimally fine f-sliced, high multiplicity data in short time.

In room temperature data collection, the high frame rates featured by PILATUS3 detectors allow for outrunning of radiation damage. Recent experiments demonstrate a systematic increase in the dose tolerance of protein and virus crystals as a function of dose rate. PILATUS3 detectors allow even higher frame rates and further push the boundaries of this successful experimental strategy. Latest results obtained with PILATUS3 reveal a departure from a linear or exponential intensity decay in the diffracting power of protein crystals as a function of absorbed dose. A lag phase observed in these experiments raises the possibility of collecting substantially more data from crystals held at room temperature before a critical intensity decay is reached.

The new EIGER detector series presents a leap in HPD detector technology. Featuring 75 µm pixel size and frame rates up to 3000 Hz in combination with continuous read-out, EIGER detectors will open up new opportunities for advanced dose optimized data acquisition techniques.

HPD detectors with CdTe sensors extend the range of high quantum efficiency to 80 keV. This will allow to fully exploit the potential of new high energy and brightness undulator beamlines at unprecedented signal-to-noise ratios and data acquisition speeds.

An overview of the salient detector properties will be given and illustrated by experimental results in various applications.
[ Hide ]
Mar 21
Friday

User Science Seminar

APS Seminar
401/A1100 @ 12:00 PM
Mar 17
Monday

Development and Production of NSLS-II by AES MOM Vacuum Group

Speaker: John Zientek, APS-AES
ASD Seminar
401/A1100 @ 1:30 PM
View Description
An overview of the role that the AES-MOM vacuum group contributed to the NSLS II project. A 6-year project started with contributing to final designs focused to weld joints and vacuum certification. Our group then focused on automated weld development, pre-production welding, Q/A measurement, cleaning and testing. After several full size pre-production vacuum chambers we completed and vacuum certified, the group then went into full production of NSLS II completing an average of 8 chambers a month on time and under budget. NSLS II is in last phase of construction and be ready for operation in 2015.
[ Hide ]
Mar 17
Monday

Silicon and Germanium Detector Developments at BNL

Speaker: Peter Siddons, Brookhaven National Laboratory
APS Upgrade Seminar
401/A1100 @ 11:00 AM
View Description
The talk will outline several x-ray detector developments at BNL, including spectroscopy and position-sensing projects. Our recent advances in combining BNL-designed ASICs with monolithic segmented germanium detectors from Semikon Detectors GmBH will be described in some detail.
[ Hide ]
Mar 14
Friday

User Science Seminar

APS Seminar
401/A1100 @ 12:00 PM
Mar 12
Wednesday

High Frequency Effects of Impedance and Coatings in the CLIC Damping Rings

Speaker: Eirini Koukovini-Platia, CERN
APS Seminar
401/B4100 @ 11:00 AM
View Description
Single bunch instability thresholds and the associated coherent tune shifts have been evaluated in the transverse plane for the damping rings (DR) of the Compact Linear Collider (CLIC). A multi-kick version of the HEADTAIL code was used to study the instability thresholds in the case where different impedance contributions are taken into account such as the broad-band resonator model in combination with the resistive wall contribution from the arcs and the wigglers of the DR. Preliminary studies on the impact of the strip-line kickers are also addressed. Coating materials will be used in the CLIC DR to suppress two-stream effects. In particular, NEG coating is necessary to suppress fast beam ion instabilities in the electron damping ring (EDR). The EM characterization of the material properties up to high frequencies is required for the impedance modeling of the CLIC DR components. The EM properties in the frequency range 9 - 12 GHz are determined with the waveguide method, based on a combination of experimental measurements of the complex transmission coefficient S21 and CST 3D EM simulations. The results obtained from a NEG coated copper (Cu) and a stainless steel waveguide are presented.
[ Hide ]
Mar 11
Tuesday

APS Web Help Desk

APS Workshop
401/A1100 @ 2:00 PM
Mar 11
Tuesday

Physics and Chemistry of Vacancy Defects in Graphene Layers: Scanning Tunneling Microscopy and Density Functional Theory Study

Speaker: Maxim Ziatdinov , Tokyo Institute of Technology
XSD Presentation
431/C010 @ 11:00 AM
Mar 7
Friday

User Science Seminar

APS Seminar
401/A1100 @ 12:00 PM
Mar 6
Thursday

Synthesis of ITO Nanoparticles with Shape Control and their Assembly for Solution-Processed Transparent Electrodes

Speaker: Jonghun Lee, Brown University
XSD Presentation
432/C010 @ 2:30 PM
Mar 5
Wednesday

Multiphysics Simulations of Beam Dynamics, Synchrotron and Free Electron Laser Radiation

Speaker: Ilya Agapov, European XFEL
ASD Seminar
401/A1100 @ 2:30 PM
View Description
In this talk I will present the newly developed software framework for multiphysics simulations of charged particle beam dynamics, synchrotron radiation, and free electron laser radiation. The following practical applications will be discussed:
  • Prediction of radiation properties at the European XFEL.
  • Nonlinear dynamics studies in synchrotrons, influence of insertion devices on dynamic aperture, on the example of PETRAIII.
  • Potential of a longitudinally focusing insertion for short bunches and free electron lasing in a synchrotron.

[ Hide ]
Feb 28
Friday

User Science Seminar

APS Seminar
401/A1100 @ 12:00 PM
Feb 21
Friday

User Science Seminar

APS Seminar
401/A5000 @ 12:00 PM
Feb 14
Friday

User Science Seminar

APS Seminar
401/A1100 @ 12:00 PM
Feb 13
Thursday

A Large Area CMOS Detector for Shutterless Collection of X-ray Diffraction Data

Speaker: Ed Westbrook, Research Detectors Inc.
APS Presentation
401/A1100 @ 10:30 AM
View Description
Driven by enormous market potential in medical imaging, recent developments in CMOS devices have improved their radiation hardness, response linearity, readout noise, thermal noise, and dynamic range, such that they are now suitable for x-ray crystallography detectors. Large (14.8 x 9.4 cm) CMOS sensors with a pixel size of 100 x100 microns are now available that can be butted together on three sides. We have fabricated a 6-tile system in a 2x3 array with a 29.5 x 28.2 cm continuous imaging area. To make an x-ray detector the CMOS sensor is covered with a 3 mm flat fibre-optic plate (for radiation protection) and a Gd2O2S:Tb phosphor screen. A special feature of these systems is that they can be read out continuously at up to 30 frames/sec with excellent dynamic range, without interrupting data collection.We have installed this system on beamline 4.2.2 of the Advanced Light Source synchrotron. Excellent data sets are now routinely recorded with this system. Typical data sets are recorded without an x-ray shutter, rotating the crystal sample continuously with an exposure time of 0.1 sec/frame and a rotation speed of 1°/sec over a 180° range. Such 1,800-frame datasets are easily processed with standard data analysis programs (e.g. D*TREK, XDS). Experimental anomalous dispersion phases are determined in the Phoenix program suite. The crystallographic results are typically significantly better than equivalent data recorded on a conventional CCD system, due to the 10X finer angular resolution of the recorded data.Very large CMOS systems (active areas up to 56 x 59 cm2 with 33 x 106 pixels) can now also be made.

Development of this technology has been supported by NIH General Medical Sciences grants R43 GM085937-01, R44 GM085937-02, and R43 GM100648-01.
[ Hide ]
Feb 10
Monday

Elucidating the Structure-Performance Relationship in Organic Photovoltaics (OPVs) by Grazing Incidence X-Ray Scattering

Speaker: Joseph Strzalka, X-ray Science Division/Time Resolved Research
XSD Presentation
401/A1100 @ 2:00 PM
View Description
Since the introduction of the Bulk Heterojunction (BHJ) architecture in the mid- 90s, organic photovoltaic devices have made steady progress toward improved power conversion efficiency, and are now poised to move from niche products to large scale commercial applications. In the BHJ, the photoactive layer consists of electron donor and acceptor materials in a bicontinuous phase blended on the nanoscale. Grazing incidence x-ray scattering, capable of characterizing thin film nanomorphology of surfaces and interfaces, has emerged as a key technique for investigating OPV materials. The hierarchical variety of lengthscales present in OPV materials requires both grazing incidence small- and wide-angle x-ray scattering, the latter recently enabled by improvements to the GISAXS instrument at 8-ID-E. I will describe grazing-incidence studies at 8-ID-E that have contributed toward unraveling the complex relationship between OPV materials, processing and performance.
[ Hide ]
Feb 7
Friday

User Science Seminar

APS Seminar
401/A1100 @ 12:00 PM
Feb 5
Wednesday

Putting the Squeeze on Biology: Biomolecules Under Pressure

Speaker: Sol M. Gruner, Cornell University
APS Colloquium
402/AUD @ 3:00 PM
Feb 4
Tuesday

Solving the Phase Diagram of the Model Quantum Magnet SrCu2(BO3)2

Speaker: Sara Haravifard, Argonne National Laboratory & The University of Chicago
XSD Presentation
432/C010 @ 2:00 PM
View Description
Low dimensional quantum magnets provide a framework for exotic phase behavior in new materials, with high temperature superconductivity being the most appreciated example. SrCu2(BO3)2 (SCBO), is a rare example of a quasi two-dimensional quantum magnet for which an exact theoretical solution exists. It serves as an experimental realization of the Shastry-Sutherland model for interacting S=1/2 dimers. The ratio of the intra and inter-dimer exchange interactions in this compound is close to a quantum critical point, where the ground state is predicted to transform from a gapped, non-magnetic singlet state to a gapless long-range ordered antiferromagnetic state as a function of the ratio of the strength of the magnetic interactions. We conducted high resolution neutron scattering measurements on SCBO in its singlet ground state which identified the most prominent features of the spin excitation spectrum, including the presence of one and two triplet excitations and weak dispersion characteristic of sub-leading terms in the spin Hamiltonian. Additionally, we investigated the pressure-driven quantum phase transition in SCBO using synchrotron X-ray diffraction and neutron scattering. In these studies we were able to investigate the evolution of both the magnetic and structural properties of SCBO up to pressures of 6 Gpa, following the development and evolution of long-range magnetic order. Moreover, the resemblance between the spin gap behavior in the Mott insulator SCBO and that associated with high temperature superconductors motivated us to explore the significance of doping on the phase diagram.
[ Hide ]
Jan 28
Tuesday

Novel Industrial Ultrafast Lasers and their Applications in Free Electron Lasers and Synchrotrons

Speaker: Yoann A. Zaouter, Amplitude Systemes
XSD Presentation
433/C010 @ 10:00 AM
View Description
he aim of this presentation is to introduce the novel industrial ultrafast laser technologies that are developed at Amplitude Systemes. These lasers benefit from several technological breakthroughs such as direct diode pumping and novel laser architectures, and gain media that allow the laser to operate simultaneously at high energies, average powers and therefore repetition rates. We will also specifically show where they are used in FEL and synchrotron and how they advantageously can replace ageing laser technologies and improve the reliability of photoinjectors, minimize the down times, improve signal to noise ratio of measurements, etc.
[ Hide ]
Jan 20
Monday

Vacuum Group UHV Support and Services to APS, Argonne and National Laboratories

Speaker: John Hoyt and John Zientek, APS-AES
ASD Seminar
401/A1100 @ 1:30 PM
View Description
The Vacuum Group at Argonne National Laboratory delivers engineering support to the Advanced Photon source, beamline users, Argonne and its sister laboratories. The Vacuum Group has been at Argonne since the APS was being built. The group has aided in design and manufacture of the APS and many other accelerator systems. The continued focus is the maintenance and upgrade of the APS by utilizing new UHV technology and practices.

The group also pursues R&D activities for future accelerator and beamline components. All new UHV designs need to be tested and that is where this group comes in. We have the facilities and knowledge to aid in the design and completion of UHV systems.
[ Hide ]
Jan 15
Wednesday

Wave Propagation Through Random Media: Branched Flow from Acoustics to Ocean Waves

Speaker: Eric Heller, Harvard University
APS Colloquium
402/AUD @ 3:00 PM
Jan 13
Monday

Probing the Metal-Insulator Transition in Engineered NdNiO3

Speaker: Mary H. Upton, Inelastic X-ray & Nuclear Resonant Scattering (IXN)
XSD Presentation
401/A1100 @ 2:00 PM
View Description
NdNiO3, along with other rare earth nickelates, has been the focus of intense research in the last decade due to its metal-insulator transition (MIT), occurring at ~210 K in NdNiO3. The transition temperature can be tuned (or suppressed) with strain giving rise to the possibility of engineered heterostructures. There are many competing models of the MIT, of which the true nature is not known. It has been suggested that the MIT results from the emergence of a low temperature charge ordered state involving the d electrons. Alternately, it may result from the opening of a charge transfer gap between the Ni d and O p electrons. We report on the effect of epitaxial strain and temperature on d-electrons in NdNiO3 as measured by bulk-sensitive resonant inelastic x-ray scattering.
[ Hide ]
Jan 13
Monday

Engineering the Elasticity of Soft Colloidal Materials Through Surface Modification and Shape Anisotropy

Speaker: Lillian C. Hsiao, University of Michigan, Ann Arbor
XSD Presentation
401/A1100 @ 11:00 AM
View Description
Designing complex fluids has always involved the arduous manipulation of system-specific parameters. Recently, we developed a general correlation to predict the flow behavior of a range of soft matter based on their microstructure. By applying the framework of structural rigidity at the macroscale (bridges, buildings, domes) to the microscale, we are able to explain the nonlinear elasticity of colloids flowing at high rates that are typical of industrial processing. In particular, we explore the idea that colloidal gels can be designed with better mechanical properties and stability without resorting to a greater quantity of materials, simply by incorporating particles with different shapes, sizes, and roughness. Biphasic particles with metallic facets have also been proposed to provide extraordinary structural strength due to their interaction anisotropy. We test these ideas by synthesizing monophasic and biphasic colloids of controlled roughness in various ellipsoidal shapes, dispersing the particles in refractive-index matched solvents, and inducing self-assembly and gelation with a measurable and tunable depletion attraction. To quantify their flow properties, rheological measurements are carried out in conjunction with microscopy experiments and direct force measurements using optical tweezers. Our understanding of gel physics and rheology shows that the trial-and-error engineering of viscoelasticity can be mitigated by applying the principle of structural rigidity to material design; for example, engineers can incorporate smaller ellipsoidal particles to increase yield stress without a significant increase in the production cost.
[ Hide ]
Jan 10
Friday

Light-X-ray Scattering and Rheology of Soft Matter

Speaker: Yu-Ho Wen, Cornell University
XSD Presentation
401/A1100 @ 11:00 AM
View Description
Soft matter is an important class of molecular materials, typically composed of polymers, colloids, and other mesoscopic constituents. They are indispensible in contemporary technological applications—for example, solid electrolytes in rechargeable lithium batteries and solution-cast thin film in polymer light-emitting diodes (PLEDs). Herein we report on the dynamics and structure of the two advanced materials—nanoparticle salts and conjugated polymers. The nanoparticle salts are created by cofunctionalization of metal oxide nanoparticles with tethered salts and neutral organic ligands, and are shown to exhibit equilibrium, Newtonian flow behaviors. We find that ionic cross-links between the salts can be created/weakened by variations of counterion size and dielectric medium. Scrutiny into the SAXS structure factors and plateau moduli further disclosed that nanoscale interparticle spacing imposed on tethered molecules produces topological constraints analogous to those in entangled polymers, uncovering the molecular origin of a similar plateau modulus shared with polymer-tethered nanoparticles and entangled polymer melts. Time-composition superposition of linear viscoelastic data further indicates stricking dynamical similarities between the two systems. In the second part, we propose a self-consistent formulation for analyzing the dynamic structure factor of aggregate species in conjugated polymer solutions, where a wide size distribution and unknown aggregate morphology, as well as pronounced interferences between translational and interior segmental motions of aggregate clusters have posed stringent challenges for conventional light-scattering analyses. Additionally, in situ rheological and turbidity measurements reveal that an externally imposed flow can result in instant and/or persistent changes in the bulk aggregation state of the precursor solutions.
[ Hide ]
Jan 9
Thursday

Hierarchical Semiconductor, Metal and Hybrid Nanostructures and the Study of their Light-Matter Interactions

Speaker: Anna Lee, University of Toronto
XSD Presentation
401/A1100 @ 2:00 PM
View Description
The interdisciplinary work during my Ph.D. and post-doctoral studies (Dept. of Chemistry and Dept. of Electrical Engineering, University of Toronto) explore the optical properties of hierarchical structures composed of nanoscale building blocks ranging from metals to semiconductors and composites, organized through bottom-up design methods.

This talk is comprised of three main research projects for which the common thread is the rational design of nanoscale assembled structures and their interactions with light.

Recent advances in spectrally tunable solution-processed metal nanoparticles have provided unprecedented control over light at the nanoscale. The plasmonic properties of metal nanoparticles have been explored as optical signal enhancers for applications ranging from sensing to nanoelectronics. Specifically, (1) by following the dynamic generation of hot spots in self-assembled chains of gold nanorods (NRs), we have established a direct correlation between ensemble-averaged surface- enhanced Raman scattering (SERS) and extinction properties of these nanoscale chains in a solution state. Experimental results were supported by comprehensive finite-difference time-domain simulations. Building from this, (2) we studied an alternate geometry, namely side-by-side assembled NRs. There is a general misconception that aggregates of metal nanoparticles are more efficient SERS probes than individual nanoparticles, due to the enhancement of the electric field in the interparicle gaps. However, we have shown through theoretical and experimental analyses that this is not the case for side-by-side assembled gold NRs. (3) Progress in colloidal quantum dot photovoltaics offers the potential for low-cost, large-area solar power; however, these devices suffer from poor quantum efficiency in the more weakly-absorbed near infrared portion of the sun’s spectrum. Here, I will talk about a plasmonic-excitonic solar cell that combines two jointly-tuned solution processed infrared materials. We show through experiment and theory that a plasmonic- excitonic design using gold nanoshells with optimized single-particle scattering-to- absorption cross section ratios leads to a strong enhancement in near-field absorption and resultant photocurrent in the performance-limiting near infrared spectral region. The present work offers guidance towards the establishment of “design rules” for the development of colloidal nanoparticle assembled systems for plasmonic sensing applications.
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