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
Friday, December 9, 2016, 1:00 pm
Eun Ju Moon
"Control of magnetic oxide interfaces through engineering octahedral distortions"
Abstract: The distortions and rotations of the corner-connected BO6 octahedra in ABO3 perovskite heterostructures play a crucial role to design and to control multifunctional properties. However, isolating the effect of the subtle octahedral interface coupling is challenging and it is difficult to identify the length scale. Here I will discuss how magnetic behavior can be tailored by structural interfacial coupling of the BO6 octahedra. In epitaxial ultrathin manganite films, different substrate-induced octahedral distortions are shown to affect the magnetic and electronic properties of the ultrathin films. Isovalent manganite superlattices will be presented in which magnetic behavior can be spatially confined by tuning the superlattice period relative to the length scale of interfacial octahedral coupling. Next, I will demonstrate a structural “delta doping” approach, non-charge-based, for controlling magnetism in ultrathin layers within superlattices. Polarized neutron reflectivity and temperature dependent magnetization measurements was used to correlate enhanced magnetization with local regions of suppressed octahedral rotations in the heterostructures. The atomic-scale modulations of the magnetism in oxide interfaces derived solely from structural effects highlights the design of local rotational gradients as routes to spatial control over novel electronic or ferroic states in oxide superlattices.
 E. J. Moon, et al. Nature Communications, 5, 5710 (2014).
 E. J. Moon, et al. Physical Review Applied, 1 (5), 054006 (2014).
 E. J. Moon, et al. Nano Letters, 14 (5), 2509 (2014).
Friday, November 4, 2016, 1:00 pm
"Advanced accelerator concepts across the electromagnetic spectrum: from microwaves to laser beams"
Abstract: I will review several accelerator-related activities in our group that span a broad range of topics, from laser-plasma accelerators to surface-wave accelerators operating at mid-IR frequencies, to microwave-based accelerators. After reviewing the basics of laser-plasma acceleration, I will describe a new approach to electron acceleration in plasma that integrates direct laser acceleration (DLA) with laser wakefield acceleration (LWFA). This approach confers several benefits over both schemes taken separately . I will also describe our ongoing effort on making surface wave accelerator based on SiC (SWABSiC) that utilizes unique polaritonic properties of SiC: its negative dielectric permittivity around the 10 microns wavelength. SWABSiC is comprised of two slabs of SiC separated by a narrow (micron-scale) vacuum gap through which the accelerated electron bunches are propagated  and accelerated by mid-infrared surface waves. The surfaces waves can be either externally driven by a CO2 laser pulse, or internally excited by a short electron bunch (or sequence of bunches) in the wakefield geometry. Recent results obtained at the Advanced Test Facility (ATF) at Brookhaven will be discussed. Finally, I will review our work on microwave photonic topological isolators  and briefly describe the new concept that we are starting to pursue: a two-beam topological accelerator.
 X. Zhang, V. N. Khudik, and G. Shvets, Phys. Rev. Lett. 114, 184801 (2015).
 B. Neuner III, D. Korobkin, G. Ferro, and G. Shvets, PRSTAB 15, 031302 (2012).
 K. Lai, T. Ma, X. Bo, S. Anlage, and G. Shvets, "Experimental Realization of a Refections-Free Compact Delay Line Based on a Photonic Topological Insulator", Scientific Reports 6:28453 (2016).
Tuesday, October 18, 2016, 1:00 pm
"Longitudinal Beam Dynamics in the CERN Proton Synchrotron Booster after LS2"
Abstract: The Proton Synchrotron Booster (PSB), composed of four nearly identical superimposed rings, is the first synchrotron in the proton injection chain of the LHC. As part of the LHC Injectors Upgrade (LIU) project the PSB will be upgraded to produce higher brightness beams. Present operation has injection at a kinetic energy of 60 MeV, and extraction at 1.4 GeV, with β ranging from 0.3 to 0.9, and correspondingly a very large frequency swing of the RF from 0.6 MHz to 1.8MHz. After upgrades the injection energy will rise to 160 MeV, with extraction at 2 GeV.
The large frequency swing is currently achieved using tunable narrow-band ferrite cavities in three RF systems operating at 1st, 2nd and up to 10th harmonic. The 1st and 2nd harmonics are used for acceleration and bunch shaping, and the high harmonic is used for longitudinal emittance blow-up. During Long Shutdown 2 (LS2) the PSB will be upgraded to use an entirely Finemet RF system, comprised of three identical cavities per ring. The broad band impedance of the Finemet will allow voltage to be distributed across the harmonics in any desirable way and remove the need for tuning loops, increasing both flexibility and reliability, whilst reducing complexity.
This talk focuses on longitudinal beam dynamics in light of the planned upgrades. The present operation of the machine will be discussed, including measurements, simulations, and operational experience with a Finemet test cavity. The benefits of the new Finemet system, compared to the existing ferrite systems, will be analysed. Finally beam dynamics studies of expected operation after LS2 will be presented.
Friday, October 14, 2016, 1:00 pm
Illinois Institute of Technology
"The BioCAT facility for biological non-crystaline diffraction and scattering at the Advanced Photon Source"
Abstract: The BioCAT Biotechnology Research Resource operates X-ray beamline 18ID at the Advanced Photon Source, Argonne National Laboratory. Now in its 20th year of operation, it is a mature, productive facility with many capabilities unique in the USA, and, arguably, the world. The high flux and excellent beam quality delivered by Beamline 18ID when matched with BioCAT’s specialized X-ray detectors is ideal for static, time- and spatially-resolved fiber diffraction. Our muscle diffraction program addresses questions regarding basic mechanisms of muscle contraction and regulation but also the structural basis of cardiac muscle disease such as heart failure and various inherited cardiomyopathies. Our fiber crystallography program addresses such questions as structure of filamentous viruses, amyloids, prions, and fibrous collagens. Our scanning X-ray micro-diffraction capabilities can be combined with X-ray Fluorescent Microscopy (XFM) to study the distributions of metals and amyloid structures and their relation to neurodegenerative diseases. The high flux densities and high collimation of the X-ray beam combined with photon counting pixel array X-ray detectors is also ideal for small-angle X-ray scattering from macromolecules in solution. Our standard mode for equilibrium SAXS is in combination with inline size-exclusion chromatography allowing the study of large, biochemically unstable complexes such as nucleosomes and various macromolecular machines involved in DNA transduction that are recalcitrant to study by other biophysical techniques. Developments in time-resolved SAXS will extend available time regimes from microseconds to seconds. These techniques have been very valuable in addressing macromolecular folding studies. Recent major reductions in sample consumption, however, now allow us to extend these techniques to a much wider range of problems involving biochemical kinetics. In this talk I will provide a snapshot overview of BioCAT’s current capabilities and indicate some future directions. BioCAT is supported by 9 P41 GM103622.
Tuesday, September 20, 2016, 3:00 pm
"A Better Alternative to KB Mirror?"
Abstract: I will present the concept of a newly developed axially symmetric, submicron synchrotron x-ray mirror lenses that will provide immense advantages over Kirkpatrick-Baez mirror optics, particularly for microfocusing applications.
- These intrinsic and practical advantages include:
- >4X larger x-ray flux at focus (due to >2X larger numerical aperture)
- Potential for 2X higher spatial resolution (intrinsically 4nm!)
- Significantly relaxed angular vibration tolerance requirements of upstream beamline optical components, owing to shorter working distance in two orthogonal directions
- Achieving large demagnification of the source and thus small focus due to short working distance
- Substantially larger field of view to achieve high spatial resolution along the x-ray beam axis (e.g., developing super high resolution confocal microXRF)
- Light, low weight and compact form factor allows straightforward scanning of the mirror lens (particularly important when samples are difficult to scan)
- Less complex electro-mechanical system: 4 degrees of freedom instead of 8 or more
- Ease of alignment and to ensure optimal focusing
To accomplish this, Sigray has developed advanced manufacturing and metrology technology for producing axially symmetric mirror lenses. I will present the results of the x-ray mirror lens development. Also discussed will be the potential applications of the lenses and configurations for use at synchrotron sources for focusing and other exciting potential applications.
Acknowledgments go to the NSF, Division of Industrial Innovation & Partnerships for funding the development of x-ray mirror lens (IIP-1448727) and to the Department of Energy (DE-SC0015196) for their small business grants.
Friday, August 5, 2016, 1:00 pm
Tomsk State University
"Current and future directions of R&D activities in the field of chromium-compensated GaAs X-ray Sensors"
Abstract: The report provides an overview of the current state of technology and scientific investigations in the field of GaAs: Cr X-ray sensors. The analysis of the test results of pixel GaAs: Cr sensors are demonstrated. It is shown that the sensors are promising for the development of modern X-ray imaging systems. The directions of further R&D dedicated to the technology optimization and the performance improvement of GaAs: Cr sensors are proposed.
V. Novikov, A. Zarubin, A. Lozinskaya, O. Tolbanov, A. Tyazhev
Functional Electronics Laboratory of Tomsk State University, Tomsk, Russia
Thursday, July 14, 2016, 2:00 pm
Lawrence Livermore National Laboratory
"Utilizing Large High-Energy Diffraction Microscopy Data Sets to Study the Mechanical Response of Structural Materials"
Abstract: High-energy X-ray diffraction techniques capable of measuring the elastic strain in hundreds of grains simultaneously have promised to change how micromechanical models are calibrated and advanced. In practice, using such large, high-dimensional data sets for model development has proven to be difficult. Establishing new methods to link high-energy diffraction microscopy (HEDM) data and micromechanical models is crucial for optimal use of these data. The presentation will focus on two novel applications of far-field HEDM data. First, results are presented from a combined X-ray diffraction / micro-tomography experiment during the uniaxial compression of a collection of spherical, sapphire single grains. The evolution of grain stresses of ~500 grains in the assembly are shown and related to local contact geometry. The interface of this data with large numerical simulations will be discussed. Next, a method to extract the evolution of slip system strengths from different families of slip systems from HEDM data is presented. The method is used to quantify the evolution of slip system strengths in α–Phase Ti-7Al. The slip system strength data is then used to inform a micromechanical strength model. Lastly, the presentation will conclude with a discussion of implementation of new X-ray diffraction techniques at CHESS to study in-situ material evolution at smaller size and faster time scales.
This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Friday, July 8, 2016, 1:00 pm
"(GI)SAXS/WAXS applications in advanced materials: from organic electronics to nanomaterials NODE"
Abstract: Synchrotron-based x-ray scattering techniques, including Small and Wide angle x-ray scattering (SAXS/WAXS) and their grazing incidence geometry, have been broadly employed to observe the large range of d-spacing from angstroms to hundreds and characterize various materials from organic small molecule to nanoparticles and polymers. Not limited to the static status of materials, the dynamic processes have been in situ investigated to expand the new horizon to understand how and why materials nucleate, change and form under various environments, such as high pressure, high temperature, solution environment, etc. That brings the challenges to make the proper designs in beamlines and improve the analysis methods for big data.
In this talk, I will present two examples to use (GI)SAXS/WAXS techniques to characterize advanced materials and the related processes. One is to characterize the roll-to-roll manufacture of organic transistors in high spatial and time resolution. The full scenario of the crystallization processes are presented at different coating speeds to control the film growth from anisotropic to isotropic modes, which reveal the relationship between the microstructure, morphology and device performance. The other is to reconstruct the structure of supercrystals assembled by nanocrystals. The approach yields into a new method called ‘supercrystallography’, which includes the growth of large size single supercrystal, SAXS/WAXS data collection and structural reconstruction from atomic through nano to mesoscale. That enables to accurately determine the translational and orientational orderings of nanocrystals in superlattice and present an unprecedented level of inter-particle structural details. The comparison of supercrystals made by Pt nanocubes and P3Ni nano-octahedra reveals the packing geometries determined by the entropy-driven forces, which could help find feasible ways to design and fabricate supercrystals with desired properties for applications. In the end, I will illustrate some possible works in near future.
Wednesday, July 6, 2016, 10:00 am
Lawrence Berkeley National Laboratory
"Probing Condensed Matter Topology With X-rays"
Abstract: Topology studies the geometric features of objects, and their spatial relations, that are stable against continuous distortions. The topology of a condensed matter system, such as the “connectedness” of the medium or defects in an order parameter field, plays a key role in determining the system’s macroscopic properties.
In my talk, I will describe three systems that are greatly influenced by their topologies. One of my topics will be “skyrmion” defects with topologically twisted spin textures in magnetic materials, which give rise to novel Hall effects and, during electrical transport, are resistant to defect pinning. This is in contrast to defects without such topological twists, called magnetic bubbles, can be pinned by interactions with defects or destroyed by other small deformations of their spin textures. In addition, I will discuss the behavior of artificial spin ices, the topologies of which are engineered to mimic the frustration of natural spin ices, such as holmium titanate. These artificial spin ices form “magnetic monopole”-like defects. Finally, I will show recent progress in creating topological defects, i.e. orbital angular momentum (OAM), in x-ray beams. Though not a condensed matter system, electronic transitions caused by absorption of OAM x-rays obey different selection rules than those caused by non-OAM x-rays. This feature may lead to new probes of electronic structure.
Friday, July 1, 2016, 1:00 pm
SUNY Polytechnic Institute
"SYNCHROTRON X-RAY BASED METROLOGY FOR PROCESS DEVELOPMENT FOR SEMICONDUCTOR DEVICES BELOW THE 10nm TECHNOLOGY NODE"
Abstract: Continual miniaturization across the advanced technology nodes has led to the construction of very small feature sizes in semiconductor devices. Developing and improving chemical vapor deposition (CVD) and atomic layer deposition (ALD) based processes are becoming increasingly critical at such nano-length-scales for growing highly conformal and thin layered structures. For further performance improvements, researchers are either introducing or considering use of FinFETs, nanowires, dielectric materials with engineered properties, high mobility channel materials such as Ge and III-V (InGaAs, GaAs), and ultrathin and conformal metal nitride based diffusion barriers for Cu and/or Ru based metal interconnects, in conjunction with the ALD and CVD grown conformal nanostructures.
Manufacturing at this scale requires processes with control at the atomic level. Understanding the physicochemical properties of the interfacial layers, void and defect formation at the interfaces, and structure of the interfaces and the thin film layers are extremely important as they are affecting the performance of the devices like never before. The laboratory-based metrology has not been able to keep up with the sa pace and developing more easily accessible new synchrotron based characterization techniques are essential at this point.
In the first part of this presentation, the use of synchrotron grazing incidence x-ray reciprocal space maps for ALD process development for high- and higher-k phase engineering of HfO2 and ZrO2 based films deposited on Ge and Si substrates will be discussed. Next, recent rapid thermal anneal x-ray diffraction studies for finding barrier failure temperatures and activation energies of Cu-diffusion across ultra-thin ALD TaN and Ta1-xAlxNy barrier films for sub-10nm interconnect technology will be reviewed. The talk will conclude with a discussion on the requirement for non-destructive depth resolved high energy x-ray photoelectron/photoemission spectroscopy for probing properties of buried interface layers in device-grade structures. The need for employing multiple synchrotron based techniques at the same time will also be discussed.
Thursday, June 23, 2016, 9:30 am
Argonne National Laboratory
"Xray diffraction imaging at the nextgeneration synchrotrons and outlook on presentday challenges in Xray studies of mesoscopic dynamics"
Abstract: X-ray diffraction imaging if understood in a broad sense comprises a range of methods and techniques employed and under development at X-ray light source facilities. The main goal of the development is to image matter at the nanoscale with progressively improving time resolution to capture the dynamics of electrons, atoms, molecules/clusters or cells at relevant time scales. A broad range of materials containing mesoscopic objects with limited long range order remains unexplored to a large extent. Among the relevant problems, to name just a few, are atomic dynamics of amorphous solids, dynamics of biological objects, structure and dynamics of defects in crystals.
To improve properties of X-rays as a probe of mesoscopic dynamics primary attention and effort of the X-ray community are directed towards the development of X-ray sources. Remarkable results have been demonstrated recently including progress on diffraction limited sources, generation of fully coherent X-rays and pulse durations on the femtosecond timescale. At the same time, X-ray optics, metrology and related instrumentation are somewhat lagging behind which impedes realization of several core methods to study mesoscopic dynamics, methods that rely on preservation of radiation wavefront and availability of specialized instrumentation such as spectrographs for x-ray absorption spectroscopy, X-ray split-delay lines for pump-probe studies, and ultra-high-resolution inelastic X-ray spectrometers.
The content of this presentation is two-fold. While a part of it is devoted to discussion of some present-day challenges in X-ray science, the other part describes several existing gaps in X-ray optics/instrumentation development. Possible solutions to help remove these gaps are illustrated. In particular, X-ray diffraction imaging and X-ray flux monitoring optical elements are discussed as at-wavelength metrology concepts to facilitate development of novel X-ray instruments, instruments which can address the unresolved problems in mesoscopic dynamics.
Wednesday, June 22, 2016, 10:00 am
Simon Fraser University
"Peaceful Coexistence: A retrospective of the PNCSRF and Canadian activities at APS Sector 20"
Abstract: The Pacific Northwest Consortium Synchrotron Radiation Facility (PNCSRF), established as the Canadian-funded (NSERC) arm of the PNC Collaborative Access Team, survived funding changes to its US partners that saw it become partnered directly with the APS. It thrived, not just ‘survived’. PNCSRF staff helped build the beamlines and continued to develop, upgrade and assist in the operations of the sector. While primarily focused on Canadian research, as an integral part of the sector, an international clientele was supported. New capabilities were realized under the auspices of Partner User agreements, in parallel with growing communities to utilize them. The success of the PNCSRF is reflected in the contributions by members to sector publications, doing so at over twice the percentage of beamtime set aside for the PNCSRF.
Thursday, June 16, 2016, 3:30 pm
Brookhaven National Laboratory
"NSLS-II, the new synchrotron light source at Brookhaven Natl. Laboratory"
Abstract: The design and performance of the NSLS-II, the new 3rd generation light source at Brookhaven National Laboratory will be presented. The 3 GeV NSLS-II storage ring with 792 m circumference is designed for a peak brightness of 1022 photons sec-1mm-2mrad-2 (0.1%BW)-1 enabled by a beam energy of 3 GeV, a maximum design beam current of 500 mA and a horizontal beam emittance of 0.9 nm rad. Orbital stabilization systems are designed to maintain the beam position within 300 nm (< 10% of the vertical beam size). These performance parameters allow extending the investigation of the structure of matter by X-ray imaging to a spatial resolution of 1 nm and an energy resolution of 0.1 meV. The accelerator complex was constructed between 2009 and 2014 and was commissioned in 2014. The storage ring started to deliver photons to the first of the six project beamlines in October 2014. The NSLS-II project was completed in 2015 and NSLS-II is now in its 2nd year of operations. All design parameters have been demonstrated and are achieved in routine operation except for total beam current which is presently (May 2016) at 80% of the design value. The presentation will emphasize commissioning and present performance.
Friday, May 6, 2016, 1:00 pm
Aaron D. Finke
Swiss Light Source, Paul Scherrer Institute
"Recent Advances in Anomalous Phasing at the Swiss Light Source"
Abstract: Native SAD (Single-wavelength anomalous diffraction) is a powerful technique for de novo experimental phasing, which exploits the anomalous signal of atoms naturally present in biological macromolecules. However, because the element edges of common heavy atoms such as S, P, Cl, and Ca are not accessible at most beamlines, the attainable anomalous signal is very weak. We have developed a data collection strategy for collecting “true” high-multiplicity datasets on any number of crystal entities, increasing the precision of measured anomalous differences and greatly facilitating native SAD solution. In addition, recent advancements at the PX beamlines at the Swiss Light Source have facilitated and improved data collection, including the introduction of the new Dectris EIGER detector, optics upgrades, and multi-axis goniometers. The role of each of these new technologies as applied to the anomalous phasing experiment will be discussed.
Wednesday, April 27, 2016, 1:00 pm
Dr. Biao Deng
"SSRF X-ray imaging beamline and its applications"
Abstract: X-ray imaging beamline (BL13W1) is one of the seven initial beamlines at Shanghai Synchrotron Radiation Facility (SSRF) and was formally opened to users on May 6, 2009. In order to meet different requirements from the users, several experimental methods, such as micro-tomography, quantitative imaging, dynamic tomography and X-ray fluorescence tomography(XFT), have been developed, and nearly 60 papers related to those developments for this beamline have been published. The beamline will offered the user beamtime of >4000h every year and more than 300 user papers have been published in the last 6 years. The quantity and quality of the user paper outcome keep a steady increase. Some typical user experimental results will be introduced.
And a dedicated full field X-ray nano-imaging beamline based on bending magnet will be built in the SSRF phase-II project. The beamline aims at the 3D imaging of the nano-scale inner structures. The photon energy range is of 5-14keV. The design goals with the FOV of 20 microns and a spatial resolution of 20nm are proposed. The key component of TXM endstation such as the capillary condenser is a technical challenges in the beamline. SSRF is cooperating with Beijing Normal University to develop the capillary condenser.
Monday, April 18, 2016, 1:00 pm
"PIP-II Transfer Lines Design"
Abstract: Abstract: To support a world-leading neutrino program over the next two decades, Fermilab envisions a major overhaul of its injector chain. The project, dubbed Proton Improvement Plan-II (PIP-II) aims at enhancing the capabilities of the existing accelerator complex while simultaneously providing a flexible platform for future upgrades. The central element of PIP-II is a new 800 MeV superconducting linac. New transfer lines will also be needed to deliver beam to the downstream accelerators and facilities. I will discuss the principles that guided the design of the transfer lines, focusing on the constraints and requirements imposed by the existing accelerator complex. I will also present modifications implemented to comply with further requirements that emerged during the development of the project.
Friday, April 15, 2016, 2:00 pm, Room 301
MS Applied Physics
Advisor: Joel Brock
Committee Members: Ivan Bazarov, David Sagan and Ulrich Wiesner
"DYNAMICAL DIFFRACTION AS AN ANGULAR SLIT OPTICAL ELEMENT"
Abstract: X-rays have wavelength comparable to typical inter atomic spacing, which makes them useful for probing the structure of matter on atomic length scales via diffraction. Upcoming developments in x-ray sources and optics promise more coherent flux and smaller beam spots. Focusing a coherent beam to smaller size increases its angular divergence. This thesis investigates diffraction of coherent, wide angle x-ray beams of ideal crystals using numerical simulations. Detailed calculations of the dynamical diffraction of a Gaussian beam show that new effects like diffraction fringes, increased emittance, and movement of the focal plane occur when the angular opening of the beam becomes comparable to the crystal’s Darwin width. Simulation of dynamical diffraction of Gauss-Schell beams shows that the diffraction fringes are rapidly smeared out by partial coherence. Further, dynamical diffraction of partially coherent beams may lead to spatial filtering, increasing the reflected beam’s coherent fraction and decreasing its emittance. The novel effects described herein are a consequence of dynamical diffraction being equivalent to a slit in angular space.
Friday, April 15, 2016, 1:00 pm
SUNY Stony Brook
"New paradigm for the design of hybrid polymer/solid interfaces"
Abstract: The topic of this talk, ultrathin polymer films on solids, has been of vital interest in many traditional technologies as well as in new emerging nanotechnologies such as organic photovoltaics, semiconductor chips, and biosensors. There is now growing evidence that polymer chains irreversibly adsorb even onto weakly attractive solid surfaces, forming several nanometer-thick adsorbed polymer layers (“adsorbed nanolayers”). I present our recent X-ray and neutron scattering results on the structure and dynamics of the adsorbed nanolayers composed of various polymers (amorphous, semicrystalline, and blockpolymers) and their equilibrium pathway/conformation at planar and curved solid surfaces [1-7]. In addition, we found that the effects of the adsorbed nanolayers propagate into the film interior, resulting in long-range perturbations of the local structure/dynamics/property of ultrathin polymer films [1-3]. Furthermore, we have revealed that the adsorbed nanolayers play a vital role in the macroscopic stability of ultrathin polymer films . Finally, I highlight the structure and dynamics of the adsorbed nanolayers formed onto nanoparticle surfaces that play crucial roles in the rheological and mechanical properties of polymer nanocomposites .
 P. Gin et al., Phys. Rev. Lett., 109, 265501 (2012).
 N. Jiang et al., Macromolecules, 47, 2682 (2014).
 M. Asada et al., Soft Matter, 34, 6392 (2014).
 N. Jiang et al., Macromolecules 48, 1795 (2015).
 N. Jiang et al., ACS Macro Letter, 4, 838 (2015).
 M. Sen et al., ACS Macro Letter, 5, 504 (2016).
 N. Jiang et al., Soft Matter, 2016, 12, 1801 (2016).
Tuesday, March 15, 2016, 1:00 pm
"The LHeC: An electron-proton and electron-ion beam collider study at CERN"
Abstract: The presentation describes the ongoing activities at CERN for extending the physics reach of the LHC to include collisions with an additional, external electron beam. Such an extension of the LHC, the so called LHeC, could provide electron-proton collisions in the TeV centre of mass regime, opening a rich spectrum of new physics and providing the world's best resolution microscope. The presentation will address the technological and logistical challenges for such an extension and discuss the required technology R&D and test program over the coming years.
Friday, March 4, 2016, 1:00 pm
Paul Scherrer Institut
Hosted by: Bruce Dunham
"A Genetic Algorithm for Chromaticity Correction in Diffraction Limited Storage Rings"
Abstract: Multi-objective genetic algorithms are a machine learning technique that has found much success providing non-intuitive solutions to problems that are not adequately solved by analytic methods. In this talk, we will introduce genetic algorithms and apply them to the problem of chromaticity correction in diffraction limited storage rings (DLSR). The standard perturbation theory approach to this problem becomes unwieldy for the strong nonlinearities encountered in a DLSR. The genetic algorithm presented here was developed for the Swiss Light Source upgrade and reliably develops optimal chromaticity correction schemes on a time scale of a few days using moderate computing resources.
Friday, February 26, 2016, 1:00 pm
Carnegie Institution of Washington
"New Findings in Materials Under Pressure"
Abstract: Extreme conditions, and in particular extreme pressures and temperatures, produce profound effects on condensed matter and materials -- from structure, bonding, and chemical reactivity to bulk transport properties. It is now possibly to generate multimegabar pressures (e.g., >300 GPa) and temperatures from millikelvins to thousands of degrees in the laboratory under static conditions. A broad range of novel phenomena and materials are being observed, including unusual transitions between insulating and metallic phases, new superconductors and ferroelectrics, and novel structural and superhard materials. Of particular interest have been pressure-induced transitions in simple elemental and molecular systems such as hydrogen. Altogether, these studies have implications for problems in physics and chemistry, planetary science, geoscience, astrophysics, and even soft matter and biology, and the new materials being discovered may find potential applications in energy and other technologies. In this effort, large experimental facilities such as accelerator-based x-ray, neutron scattering, and large laser sources are allowing new types of measurements to be made as well as still more extreme environments to be reached in the laboratory.
Thursday, February 25, 2016, 1:00 pm
"Beam Dynamics in LCLS-II"
Abstract: LCLS-II is a proposal for a high repetition rate (1MHz) FEL, based on a CW, superconducting linac. In this talk I will review the challenge physics in the linac design. Both space charge and coherent synchrotron radiation (CSR) play important roles in affecting the beam quality by inducing spike beam, large distortion in longitudinal phase space and micro-bunch. A Fast Particle Tracking (FPT) code is developed to speed-up the optimization of the linac design. A multi-objective genetic optimizer is implemented for different bunch charges, corresponding to different operating modes, are presented.
Friday, February 19, 2016, 1:00 pm
Hosted by: Bruce Dunham
"The Cornell High Brightness Photoinjector: From Commissioning to CBETA"
Abstract: Currently, the Cornell high brightness injector holds the world record for high average current from a photoinjector with cathode lifetimes suitable for an operating user facility, as well as the record for lowest demonstrated emittance from a DC gun-based photoinjector at bunch charges on the order of up to 1 nC. In this talk I will emphasize the commissioning work and simulation tools which went into producing the low emittances measured in this machine. Additionally, I will discuss how these tools have been used in other areas, such as the Low Energy RHIC electron Cooling (LEReC) project and Ultra-fast Electron Diffraction (UED) simulations. Finally, I will highlight ongoing simulations of the injector and the Main Linac Cryomodule, as envisioned for the CBETA machine now under design and construction at Cornell.
Friday, February 12, 2016, 1:00 pm
Dr. David Douglas
"ERLs Around the World and Across Time"
Abstract: We will hold an informal town-hall-style exchange on the status of various energy-recovering linac (ERL) concepts and projects. Information from this discussion will be used in an assessment of the maturity and degree of difficulty of various ERL-related technologies. Key design and operational issues encountered to date - such as halo in high-power beams, management of collective effects, beam stability, preservation of beam quality during recirculation and conditioning for user service, and magnetic transport component field quality - will be highlighted.
Tuesday, January 19, 2016, 1:00 pm
"The SRF R&D program at CERN"