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X-RAY RUNS: Apply for Beamtime

2017  Nov 1 - Dec 21
2017  Proposal/BTR deadline: 9/1/17

January 9th - Maury Tigner, Cornell University
January 15th - Dmitry Teytelman, Dimtel, Inc. - ~SPECIAL seminar~
January 16th - Xiaowei Dong, Argonne National Laboratory
January 30th - Alexander Romanenko, Cornell University
February 6th - Prof. Ulrich Wiesner, Cornell University ~380 Wilson Lab~
February 13th - Chae Un Kim, Cornell University
February 20th - Don Hartill, Cornell University
February 27th - Suntao Wang, Cornell University
March 6th - Arthur Woll, Cornell University
March 13th - Debashis Ghosh, Hauptman-Woodward Institute
March 20th - Spring Break
March 27th - Prof. Antje Baeumner, Cornell University
April 3rd - Prof. Richard Talman, Cornell University
April 17th - Lois Pollack, Cornell University
April 24th - Ivan Bazarov, Cornell University ~380 Wilson Lab~
May 1st - Matthias Liepe, Cornell University
May 22nd - John Hill, NSLS II ~380 Wilson Lab~
May 29th - Maury Tigner
July 10th - James Ellison, University of New Mexico
July 29th - Xiongwei Zhu and Shuhong Wang, Beijing ~SPECIAL seminar~
August 7th - Chad Mitchell, University of Maryland
August 13th - Mark Pfeifer, La Trobe University ~SPECIAL seminar~
August 26th - Hermann Schmickler, CERN Cedex France ~SPECIAL seminar~
September 4th - Changchun Sun, Duke University
September 8th - Xiaoxu Li, University of Central Florida  ~SPECIAL seminar~
September 10th - Chuyu Liu, Jefferson Lab  ~SPECIAL seminar~
September 11th - Dr. Alexey Lyashenko, Yale University
September 14th - James Taylor, University of Portsmouth  ~SPECIAL seminar~
September 15th - Kiran Sonnad, University of Karlsruhe  ~SPECIAL seminar~
September 18th - Yipeng Sun, CERN  ~SPECIAL seminar~
September 18th - Dr. Nikolay Malitsky, BNL
September 29th - Cesar Luna-Chavez, University of Illinois ~SPECIAL seminar~
October 2nd - Zhi Zhao, Oakridge National Lab
October 19th - Chris Jacobsen  ~SPECIAL seminar of Interest~ Clark Hall
October 30th - Mathew Maye, Syracuse University
November 6th - Available
November 13th - Richard Gillilan, Cornell University
November 17th - Nicholas Simos, Brookhaven National Lab ~SPECIAL seminar~
November 20th - Atoosa Meseck, Helmholtz-Zentrum-Berlin
November 23rd - Dr. Luca Cultrera, INFN, Italy  ~SPECIAL seminar~
November 27th - University Holiday
December 3rd - Chae Un Kim, Cornell University ~SPECIAL seminar~
December 4th - Ilan Ben-Zvi, Brookhaven National Lab
December 11th - Jay Yu Kim, University of Colorado
December 14th - Heinz Graafsma, Deutsches Elektronen  ~SPECIAL seminar~
December 15th - Elijah Omollo Ayieta, Indiana University  ~SPECIAL seminar~
December 16th - SangHoon Nam and Heung-Sik Kan, Pohang Light Source
                        ~SPECIAL seminar~

December 18th - Panakkal Job, Brookhaven National Lab
December 21 - Sven Stoltz, Harvard University ~SPECIAL seminar~
December 23rd - William Schaff, Cornell University ~SPECIAL seminar~
December 25th - University Holiday
January 1, 2010 - University Holiday

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~SPECIAL Seminar~ Note: Date and Time

Wednesday, December 23, 2009
Time: 11AM

William Schaff,
Cornell University

"The III-Nitride Materials System for Applications Including High Brightness Photocathodes"

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~SPECIAL Seminar~ Note: Date

Monday, December 21, 2009
Time: 1PM

Sven Stoltz,
Harvard University

"Experimental Studies of Liquid Metal Surfaces"

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Friday, December 18, 2009
Time: 1PM

Dr. Panakkal Job,
Brookhaven National Lab

"Radiological Design Considerations of Electron Storage Rings"

Abstract: Brookhaven National Laboratory is in the process of constructing a new Electron Synchrotron for scientific research using synchrotron radiation. This facility, called the "National Synchrotron Light Source II" (NSLS-II), will provide x-ray radiation of ultra-high brightness and exceptional spatial and energy resolution. It will also provide advanced insertion devices, optics, detectors, and robotics, and a suite of scientific instruments designed to maximize the scientific output of the facility. The project scope includes the design, construction, installation, and commissioning of the following accelerators: a 270 MeV linac, a booster accelerator operating from 270 MeV to 3.0 GeV, and the storage ring which stores 500 mA current of electrons at an energy of 3.0 GeV. It is planned to operate the facility primarily in a top-off mode, thereby maintaining the maximum variation in stored beam current to < 1%. Because of the very demanding requirements for beam emittance and synchrotron radiation brilliance, the beam life-time is expected to be quite low, on the order of 2 hours. This makes the radiological design and operational requirements of this facility very challenging. The characteristics of the accelerators, their operating modes and the impacts on bulk shielding assumptions are discussed in this talk.

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~SPECIAL seminar~ Note: Date

Wednesday, December 16, 2009
Time: 1PM

Dr. SangHoon Nam, Deputy Director,
Pohang Light Source

Dr. Heung-Sik Kan
Pohang Light Source

"PLS-II:  Pohang Light Source upgrade project and Sc RF system for PLS-II"

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~SPECIAL seminar~  Note: Date Change

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Tuesday, December 15, 2009
Time:
 1:00 PM

Elijah Omollo Ayieta
Indiana University

"Electronic Structure of Fe Atomic Chains on Pt(997)Surface"

 

Abstract: A variety of one dimensional atomic chains can be synthesized on stepped surfaces, which provide opportunities for systematically tailoring the surface properties. The electronic structure of the high vicinal surface plays an essential role to determine the physical properties of the atomic chains. We have used the surface analysis technique to study the surface of Pt(997) single crystal. The angle resolved ultra violet photoemission spectroscopy ARPES was performed to characterize the electronic states of Pt(997) surface by using synchrotron radiation light source. Different from the free electron model on the flat Pt(111) surface, electrons are observed with wave vectors perpendicular to the step direction. Fe was careful deposited on Pt(997) substrate at room temperature. The STM data shows that the Fe was formed along the step edges due to step decoration growth. The exchange splitting of Fe 3d bands is estimated according to the photoemission spectroscopy data of Fe/Pt.

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~SPECIAL seminar~  Note: Date and Time

Download talk:  PDF

Monday, December 14, 2009
Time: 3 PM

Dr. Heinz Graafsma
Deutsches Elektronen Synchrotron

"The European XFEL project and the associated detector developments"

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Friday, December 11, 2009
Time: 1PM

Dr. Jay Yu Kim, Postdoctoral Research Assoc
University of Colorado

"Electrochemical Atomic Layer Deposition (ALD) of Platinum, Copper, and Indium Telluride and Gas-Phase ALD of Tin Monosulfide"

 

Abstract: The first topic of my talk will be about electrochemical atomic layer deposition (ALD) by ultrahigh vacuum (UHV) surface analysis.  The purpose of electrochemical ALD is to form smooth thin films at room temperature.  Indium telluride (InTe) thin film was formed by alternative layer-by-layer growth of tellurium and indium atomic layers.  Platinum and copper thin films were grown on Au(111) substrate by the surface-limited redox replacements (SLRR).  In case of forming a platinum and copper atomic layer, a copper atomic layer or a lead atomic layer, as a sacrificial layer, was first formed by underpotential deposition (UPD) on the clean and annealed Au(111) single crystal.  Then, it was immersed in the platinum and copper solution at open circuit, then a desirable metal atomic layer was formed on the substrate.  My second topic will be about gas-phase ALD of tin monosulfide (SnS).  SnS is a possible luminescent solar concentrator (LSC) material.  SnS was grown by ALD using sequential exposures of Sn(acac)2 and H2S.  In-situ quartz crystal microbalance (QCM) studies shoed that the SNS growth per ALD cycle on gold was 0.20~0.25 Å at reactor temperatures of 175°C.  The in-situ QCM growth rate shoed that the SnS thin film ALD growth was self-limiting.  X-ray reflectivity (XRR) investigations were consistent with a growth per ALD cycle of 0.23 Å at 175°C and yielded a SnS ALD film density of ~5 g/cm3.  The SnS ALD films displayed a bandgap of ~1.87 eV and showed a weak and broad photoluminescence (PL) of 550~750 nm.

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Friday, December 4, 2009
Time: 1PM

Dr. Ilan Ben-Zvi,
Brookhaven National Lab

 

"ERL and SRF activities at BNL"

 

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~SPECIAL seminar~  Note: time and place

Thursday, December 3, 2009
Time: 1PM
374 Wilson Lab

Dr. Chae Un Kim, Staff Scientist
MacCHESS

"Advanced protein crystal cryopreservation opens new windows into structural biology"

 

Abstract: A novel high-pressure cryocooling technique for macromolecular crystallography has been developed and explored at the Macromolecular Diffraction Facility at the Cornell High Energy Synchrotron Source (MacCHESS). The method involves cooling macromolecular crystals to cryogenic temperatures (~ 100 K) in high-pressure Helium gas (up to 200 MPa). In the presentation, I will explain the underlying mechanism of the method, involving high-density amorphous ice. Then I will discuss its technical applications, such as crystal cryoprotection and diffraction phasing as well as scientific applications, including ligand-binding stabilization, entrapment of gas molecules in protein, and pressure studies on protein. This new protein crystal cryopreservation method opens new windows into structural biology.

 

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~SPECIAL seminar~  Note: time and day

Download talk:  PDF

Monday, November 23, 2009
Time: 11AM

Dr. Luca Cultrera
National Institute of Nuclear Physics, Italy

"Photoemission Studies on Metallic Thin Films for SPARX Photoinjector"

Abstract: SPARC FEL project at LNF-INFN has reached important milestones opening the way to realize an X-ray FEL with SPARX project. Within SPARX R&D activities we are going to develop technological improvement in order to increase the reliability of the photoelectron source. Metallic photocathodes are the best candidates for single bunch high brightness photoinjector. Despite their claimed contamination insensivity, even in UHV (10-9 mbar range) low work function metals as Mg, Y, but also the most used and inert Cu suffer from the contamination due to chemical species present in residual gases. Recent results on photoemission properties of Mg and Y thin film based photocathodes will be illustrated and discussed.

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Friday, November 20, 2009

Atoosa Meseck
Helmholtz-Zentrum-Berlin

 

"Seeding of free electron lasers by various techniques"

 

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~SPECIAL seminar~  Note: time and day

Download talk:  PDF PPT

Monday, November 17, 2009
Time: 1:00 pm

Dr. Nicholas Simos
NSLS II Project, Brookhaven National Laboratory

"Meeting Extreme Stability Requirements of Next Generation Light Sources - NSLS II Experience"

 

Abstract: Next generation light sources and relevant vibration sensitive facilities will rely on extreme stability of both the accelerator lattice and of the experimental station in order to meet the high performance requirements of nano-scale resolution. The different requirements and stability issues that define the performance of the various integrated elements of such facilities, from the electron beam lattice to the experimental end-station receiving x-ray beams, make the challenge more formidable. While past experience on previous generation machines can aid in the development of a system design that addresses stability issues, meeting of the stringent requirements requires an extra step.

These next generation light sources as well as electron microscopy facilities are subject to natural as well as cultural noise environments which, for the most part, are unique to each facility. Therefore, to aid their design a full understanding and characterization of the respective noise environments must be achieved and integrated into the process.

The thought process behind stability of large accelerator machines as well as sensitive experimental end-stations and its integration into the design of the NSLS II light source will be presented in this talk. In particular, the close association of field measurements and high-fidelity simulations of the interaction of the accelerator with the vibration environment, currently afforded by the advancements in computational science, will be emphasized. Further, experience from other facilities aiming at high levels of vibration stability, including light sources and electron microscopes, will be addressed.

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Friday, November 13, 2009

Richard Gillilan
Sr. Research Associate
MacCHESS, Cornell University

 

 

"Structure from Solution.  Biological Small-Angle X-ray Scattering"

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Friday, October 30, 2009

Mathew Maye, Asst. Professor
Dept of Chemistry
Syracuse University

 

"SAXS For Probing Interparticle Spatial Properties in 3D Nanoparticle Assemblies"

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~SPECIAL seminar of Interest~

Monday, October 19, 2009
Location: 700 Clark Hall
Time:  12:45pm

Chris Jacobsen
SUNY Stony Brook

"Small Wavelengths and Big Problems: Nanoscale Studies Using X-ray Microscopy"

Abstract: Advances in the nanofabrication of x-ray optics are leading to new opportunities for studies of structure, chemical speciation, and elemental distribution, and with samples too thick to view using electron microscopy. By overcoming challenges in optics fabrication and specimen freezing, and employing emerging high brightness x-ray sources, one can contribute to the understanding of big problems like fuel production from biomass, global carbon cycling, and biochemical speciation in cells.

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Friday, October 2, 2009

Zhi Zhao
Oakridge National Lab

"Cavity Enhancement of Picosecond Optical Pulses for Laser Stripping"

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~SPECIAL seminar~  Note: change of day

Tuesday, September 29, 2009

Cesar Luna-Chavez
University of Illinois at Urbana-Champaign

"Biophysical Studies of Membrane Protein Complexes: Protein-Protein Interaction, Microheterogeneity, Oligomerization, Solubility and their influential role in protein characterization and crystallization"

Abstract: Results from several biophysical techniques that have provided insights into the structures of biological macromolecules will be presented in an effort to propose a downstream process that would be universally useful for the structure-function study of membrane proteins. Currently, high-resolution structural studies of Integral Membrane Proteins (IMPs) have been hindered by their recalcitrance to be expressed, purified, and/or characterized to produce crystals suitable for diffraction studies. One main difficulty associated with their crystallization is the tendency of IMPs to aggregate during crystallization. Another important factor governing crystallization is the choice of detergent used during solubilization of the cell membranes to release the protein of interest. These amphiphiles can also interfere with the structural properties of the proteins and together with the loss of surrounding lipid can promote denaturation and aggregation or sometimes interfere with the IMP characterization. Even when large crystals of these biological macromolecules are obtained, they diffract poorly due to internal disorder and mostly due to the microheterogeneity contamination in the sample. Even though an estimated 30-40% of all genes code for IMPs and they constitute more than 60% of all drug targets, during the past decade, barely one hundred unique IMP structures have been solved and each structure has made a major contribution in its area of science. That translates to < 1% of the structures currently deposited in the PDB site are of membrane proteins. I will present improved or newly developed strategies for protein engineering, expression of proteins, purification, assay development and kinetic characterization of IMPs from projects involving recombinant IMPs from E. coli and projects focused on development of an integrated set of high throughput strategies to identify and characterize novel multi IMP supercomplexes in large scale natively purified from two hyperthermophilic organisms. Some of these techniques provide insights into the structures of macromolecules at high resolution and those which have not been probed by or remain intractable to atomic resolution have been characterized by SAXS which may be powerfully combined with information from crystallographic resolution and computational structure prediction methods.

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Friday, September 18, 2009

Dr. Nikolay Malitsky
Brookhaven National Lab

"EPICS-DDS: Rationale, Status, and Applications"

Abstract: EPICS-DDS is an open source implementation of the Object Management Group (OMG) Data Distribution Service (DDS) middleware based on the Channel Access protocol of the Experimental Physics and Industrial Control System (EPICS). The talk considers the different features of the EPICS-DDS project in the context of the NSLS-II high level application environment, presents its current scope, including key middle layer servers, such as Machine, Online Model and Virtual Accelerator, and discusses future directions.

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~SPECIAL seminar~  Note: change of time

Download talk:  PDF

Friday, September 18, 2009
Time:
 10:00 AM

Yipeng Sun
CERN

"Beam Dynamics Aspects of Crab Cavities in the Large Hadron Collider"

Abstract: Modern colliders bring into collision a large number of bunches to achieve a high luminosity. The long-range beam-beam effects arising from parasitic encounters at such colliders are mitigated by introducing a crossing angle. Under these conditions, crab cavities (CC) can be used to restore effective head-on collisions and thereby to increase the geometric luminosity. Such crab cavities have been proposed for both linear and circular colliders. The crab cavities are RF cavities operated in a transverse dipole mode, which imparts on the beam particles a transverse kick that varies with the longitudinal position along the bunch. The use of crab cavities in the Large Hadron Collider (LHC) may not only raise the luminosity, but it could also complicate the beam dynamics, e.g. crab cavities might not only cancel synchro-betatron resonances excited by the crossing angle but they could also excite new ones, they could reduce the dynamic aperture for off-momentum particles, they could influence the aperture and orbit, also degrade the collimation cleaning efficiency, and so on. In this paper, we explore the principal feasibility of LHC crab cavities from beam-dynamics point of view. The implications of the crab cavities for the LHC optics, analytical and numerical luminosity studies, dynamic aperture, aperture and beta-beating, emittance growth, beam-beam tune shift, long-range collisions, and synchro-betatron resonances, crab dispersion and collimation efficiency will be discussed.

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~SPECIAL seminar~  Note: change of day

Tuesday, September 15, 2009

Dr. Kiran Sonnad
Laboratory for Applications of Synchrotron Radiation
University of Karlsruhe

 

"Electron Clouds: Their Diagnostics and Simulation of their Effects"

Abstract: Electron clouds are known to have detrimental effects over the quality of the beam. They are foreseen to pose problems in several future accelerator facilities and proposed upgrades of existing ones. This presentation will cover aspects of two key areas of electron cloud studies. Their diagnostics using the microwave transmission method and calculation of their effects on the beam. The first part of this talk will discuss the microwave transmission experiments conducted at PEP II, emphasizing on the theory and simulation work that accompanied these experiments. Some attempts at repeating this experiment at the ANKA storage ring will also be discussed. The second part will deal with calculations of emittance growth due to electron cloud effects. This part will show results of a study done for the planned upgrade of the Fermilab main injector and also some studies on comparison of results obtained from different codes

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~SPECIAL seminar~  Note: change of day

Monday, September 14, 2009

James Taylor
Research Fellow, Inst. of Biomedical and Biomolecular Science,
University of Portsmouth

 

 

"Low-resolution Shape Determination of Large Multi-subunit Complexes of the Restriction-modification System EcoR124I"

J. Taylor1, A. Swiderka1, P. Callow2, and G. Kneale1

1Institute of Biomedical and Biomolecular Sciences, University of Portsmouth, UK
2Partnership for Structural Biology, Institut Laue Langevin, 38042 Grenoble, France

Email: james.taylor@port.ac.uk Website: taylorj.co.uk

Type I restriction-modification (R-M) systems are comprised of three genes HsdS, HsdM and HsdR. The R-M system EcoR124I, is composed of two multi-subunit complexes, the 162 kDa methyltransferase (MTase), responsible for methylation of DNA and the 400 kDa restriction endonuclease (ENase), responsible for DNA cleavage. I will describe our use of small-angle neutron scattering complemented by other low-resolution techniques such as analytical ultracentrifugation and high-resolution techniques such X-ray crystallography, to describe the subunit assembly and structural changes that occur when the methyltransferase is switched to an endonuclease through the addition of two R subunits. Small-angle neutron scattering data was collected at ILL, Grenoble. The resulting scattering profiles and distance distribution functions of the genetically engineered MTase were similar to those both for the wild-type MTase and related methyltransferase, M.AhdI1. Next, the restriction endonuclease R.EcoR124I, was reconstituted both as a R1 and R2 complex (having either one or two copies of the R subunit) and neutron scattering data was collected in the absence and presence of DNA. Ab initio methods have been used to determine the shape of R, which was used as a constraint for determining a high resolution model2. Furthermore, the ab initio model of R has assisted the determination of the position of each R subunit when bound to the MTase, to form the ENase. This has been achieved by using contrast variation, whereby, scattering measurements of ENase (composed of deuterated R and protonated MTase) were made in a range of D2O/H2O ratios. Finally, rigid-body modelling has been used to construct a high-resolution model of the location of each R subunit. This has revealed for the first time, how the endonuclease domains of each R subunit could cause single-stranded DNA breaks on each strand of foreign DNA from bacteriophage and viruses, thus protecting the host cell.

[1] P. Callow, A. Sukhodub, J.E. Taylor, and G.G. Kneale; "Shape and Subunit Organisation of the DNA Methyltransferase M. AhdI by Small-angle Neutron Scattering", Journal of Molecular Biology 369, 177-185 (2007)

[2] A. Obarska-Kosinska*, J.E. Taylor*, P. Callow, J. Orlowski, J.M. Bujnicki, and G.G. Kneale, "HsdR Subunit of the Type I Restriction-modification Enzyme EcoR124I: biophysical characterisation and structural modeling", Journal of Molecular Biology 376, 438-452, * joint first authors (2008)

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Friday, September 11, 2009

Dr. Alexey Lyashenko
Yale University

 

 

"Alkali-antimonide Photocathodes for Gas-Avalanche Photomultipliers"

Abstract: We summarize the development of visible-sensitive gaseous photomultipliers, combining a semitransparent bialkali photocathode with a state-of-the-art cascaded electron multiplier. The latter has high photoelectron collection efficiency and a record ion blocking capability. We describe in details the system and methods of photocathode production and characterization, their coupling with the electron multiplier and the gaseous-photomultiplier operation and characterization in a continuous mode.

We present results on the properties of laboratory-produced K2CsSb, Cs3Sb and Na2KSb photocathodes and report on their stability and QE in gas; K2CsSb photocathodes yielded QE values in Ar/CH4(95/5) above 30% at wavelengths of 360-400 nm. The novel gas photomultiplier yielded stable operation at gains of 105, in continuous operation mode, in 700 Torr of this gas. The photomultiplier's sensitivity to single photons was demonstrated in pulsed operation mode. Other properties are described. The successful detection of visible light with this gas-photomultiplier pave ways towards further development of large-area sealed imaging detectors, of flat geometry, insensitive to magnetic fields, which might have significant impact on light detection in numerous fields.

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~SPECIAL seminar~  Note: change of day & time

Download talk:  PDF

Thursday, September 10, 2009
Time:
2:30PM

Chuyu Liu,
Center for Advanced Studies of Accelerators
Jefferson Lab

 

 

"Laser System for Compton Polarimeter and ODR Beam Size Measurement"

Abstract:  The laser system designed for Compton palarimeter features high repetition rate (499MHz), short pulses (~20ps), high power (>10W) and high energy (532nm). In the talk, a prototype laser system, which is composed of a gain-switched diode laser (fiber-coupled), fiber amplifier and frequency doubling system will be presented. The pulse picking and pulse forming techniques were demonstrated on the gain-switched diode seed, which makes gain-switched diode seed an excellent candidate for short pulse drive laser with flexible rep rate. Two issues pertaining to laser beam shaper design will be discussed and a new single element shaper design will be presented. In the end, optical diffraction radiation electron beam size measurement will be mentioned.

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~SPECIAL seminar~  Note: change of day & time

Tuesday, September 8, 2009
Time:
1:30PM

Xiaoxu Li,
Optical Fiber Communications,
CREOL, University of Central Florida

 

 

"Wavelength-division-multiplexed Transmission using Semiconductor Optical Amplifiers and Electronic Impairments Compensation"

Abstract:  Over the last decade, the rapid growth in the demand of novel broad-band services keeps stimulating research on increasing transmission capacity in fiber-optic communication systems. Wavelength division multiplexing (WDM) technology has been widely used in fiber-optic systems to fully utilize the transmission bandwidth. Among the optical amplifiers for WDM transmission, semiconductor optical amplifier (SOA) is a promising candidate, thanks to its broad bandwidth, compact size, and low cost.

In this dissertation, WDM transmissions using SOAs are first demonstrated in the 1310 nm window to investigate the feasibility of increasing the capacity of existing telecommunication network. An error-free transmission of 4 × 10 Gbit/s differential phase-shift keying signals over 540 km standard single mode fiber (SSMF) is achieved.

To look into its applications for WDM transmission, a novel SOA based on quantum-dot (QD) structure is studied theoretically. The QD-SOA is modeled with the assumption of overall charge neutrality. Static gain is calculated and optical modulation response and nonlinear phase noise are studied semi-analytically based on small-signal analysis. The quantitative studies show that an ultrafast gain recovery time of ~0.1 ps can be achieved when QD-SOAs are under high current injection, which leads to high saturation output power however more nonlinear phase noise when the QD-SOAs are used in the transmission systems operating at 10 Gbit/s or 40 Gbit/s.

In WDM systems using SOAs, due to the large noise figure of the SOAs, high signal launching powers are required to assure reasonable optical signal-to-noise ratio of the received signals. Hence the SOAs are operated in the saturated region and the signals will suffer from the SOA impairments including self-gain modulation effect, self-phase modulation (SPM) effect, and inter channel crosstalk effects such as cross-phase modulation (XPM) and four-wave mixing (FWM). In order to increase the transmission reach of such WDM systems, those SOA impairments need to be compensated. In this proposal, an electronic post-compensation scheme for SOA impairments is proposed using coherent detection and digital signal processing (DSP) techniques. An on-off keying (OOK) transmission over 100 km SSMF and three SOAs are demonstrated experimentally with SOA IC. The data pattern effect of OOK signal is compensated effectively. Both optimum launching power and Q-factor are improved by 8 dB.

In addition to the SOA impairments, fiber impairments in the WDM systems need to be compensated because the signals are distorted by the fiber dispersion and nonlinearities such as SPM, XPM, and FWM as well. The proposed fiber IC is based on coherent detection and backward propagation method. The corresponding DSP implementation is described and the required calculations and system latency are derived. A WDM transmission of 10 × 10 Gbit/s binary phase-shift keying signals over 800 km dispersion shifted fiber with fiber IC is simulated. The results show that the FWM from fiber is compensated effectively and the transmission distance is increased by 60%. Due to the common nature of the post-compensation, the fiber IC and the SOA IC can be implemented simultaneously using coherent detection and DSP and thus the impairments in such WDM systems can be compensated thoroughly.

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Friday, September 4, 2009

Changchun Sun
Grad Student
Duke University

"Characterizations of a Compton Scattering Gamma-ray Beam and Diagnostics of an Electron Beam"

Abstract:  Compton scattering of a laser beam with a relativistic electron beam can be used to generate a high-energy gamma-ray beam, as well as to non-destructively diagnose the electron beam. In this work, we report on the characterizations of a Compton scattering gamma-ray beam. To study this gamma-ray beam, an end-to-end spectrum reconstruction method and a CCD based gamma-ray imaging system have been developed. Using Compton scattering technique, the energy of an electron beam in the Duke storage ring was accurately measured. Using Touschek lifetime technique, the radioactive polarization of the electron beam was also successfully observed.

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~SPECIAL seminar~  Note: change of day, time and PLACE

Download talk:  PDF    PPT

WEDNESDAY, August 26, 2009
PLACE:  300 Wilson Lab

Time: 10AM

Hermann Schmickler
CERN
Cedex France

"Using the CESR-TA beam to sense nanometer-size mechanical vibrations"

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~SPECIAL seminar~  Note: change of day and time

Download talk:  PDF

Thursday, August 13, 2009
Time: 11AM

Dr. Mark Pfeifer
Research Fellow
La Trobe University, Australia

"Bringing Structure and Order to Coherent X-ray Diffraction"

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Friday, August 7, 2009

Chad Mitchell
Postdoctoral Research Associate,
University of Maryland

"Computation of Transfer Maps from Surface Data with Applications to LHC Quadrupoles and ILC Damping Ring Wigglers"

PDF of talk available here

Abstract: Transfer maps for magnetic elements in storage and damping rings can depend sensitively on nonlinear fringe-field and high-order-multipole effects. The inclusion of these effects requires a detailed and realistic model of the interior and fringe magnetic fields, including their high spatial derivatives. A collection of surface fitting methods has been developed for extracting this information accurately from 3-dimensional magnetic field data on a grid, as provided by various 3-dimensional finite element field codes. The virtue of surface methods is that they exactly satisfy the Maxwell equations and are relatively insensitive to numerical noise in the data. These techniques can be used to compute, in Lie-algebraic form, realistic transfer maps for LHC final-focus quadrupoles and for the proposed ILC Damping Ring wigglers. An exactly-soluble but numerically challenging model field is used to provide a rigorous collection of performance benchmarks.

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~SPECIAL seminar~  Note: change of day

Wednesday, July 29, 2009

Xiongwei Zhu and Shuhong Wang
Institute of High Energy Physics, Beijing

Accelerator Activities at IHEP-ppt.pdf
Cornell Talk.pdf

"Design Studies on the FEL-ERL Test Facility at IHEP, Beijing"

Abstract:  A preliminary plan on the Beijing Advanced Photon Sources (BAPS) is proposed at IHEP. The 1st phase of the BAPS is a 5 GeV SR facility with ~1 nm emittance, which will be the central experimental facility for the planed Beijing Comprehensive Research Center hosted by the CAS. The 2nd and 3rd phases of the BAPS will be a XFEL based on a 6~8 GeV L-band SC linac and a 5 GeV ERL, respectively. The SC linac is planed to provide the different beams both for XFEL and ERL simultaneously. For the 2nd and 3rd phases, a FEL-ERL test facility is proposed. Some design studies on this test facility are discussed in this talk.

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Friday, July 10, 2009

James Ellison
Dept. of Mathematics & Statistics
University of New Mexico

 

"Self Consistent Mean Field Approach to CSR from Arbitrary Planar Orbits: Application to Microbunching Instability in Bunch Compressors"

Abstract:  CSR is important for many of today's electron accelerators like ERL's and X-ray FELs and its copious production is indeed the aim of most proposed light sources. On the other hand CSR can be detrimental in the functioning of these accelerators, e.g., in the bunch compressors of an FEL. We report here on the application of our accurate parallel Monte Carlo Particle (MCP) algorithm and code, which is based on a 2D Vlasov Maxwell model, to the Microbunching Instability in a Bunch Compressor. To set the stage, the bunch compression without self fields will be reviewed as well as the Vlasov Impedance, Coasting Beam Model of Heifets, Stupakov, Krinsky, and Huang, Kim (H2SK2) (PRST-AB 2002) where they introduce a "Gain Function" as a figure of merit for the instability. We then discuss the microbunching instability, which is a potentially detrimental effect of CSR, in the context of the longitudinal spatial density using our MCP code. This gives a deeper understanding of the gain function and shows that the gain function is only part of the story.

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Friday, May 29, 2009

Maury Tigner, Director
Cornell Laboratory for Accelerator-based Sciences and Education
Cornell University

 

"Advanced Accelerator Research at Fermilab"

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Friday, May 22, 2009

John Hill, Division Director for Experimental Facilities
Brookhaven National Lab
National Synchrotron Light Source II

 

"Watching Electron Dynamics with X-rays: Resonant Scattering Studies of Magnetic and Orbital Excitations in Cuprates"

Abstract:  Measurements of the electronic excitation spectrum can provide an important test of our understanding of strongly correlated electron systems. Here I discuss how the technique of Resonant Inelastic X-ray Scattering (RIXS) can provide momentum-resolved measurements of such excitations. I present two recent examples of this in cuprates. In the first, measurements in La2-xSrxCuO4 revealed a new mode at 500 meV. On the basis of its momentum, doping and temperature dependence, this is identified with two magnon scattering – the first such observation with hard x-rays. In the second example, I will discuss the search for the “orbiton” a putative excitation associated with orbital order. Recent results in KCuF3 will be presented. Finally, I will briefly discuss NSLS-II, the new synchrotron under construction at BNL.

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Friday, May 1, 2009

Asst. Prof. Matthias Liepe
Physics, Cornell University

 

 

"First Results from the Cornell High-Current ERL Injector SRF Module"

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Friday, April 24, 2009

Prof. Ivan Bazarov
Physics, Cornell University

 

 

"Initial Beam Results from the Cornell High-Current ERL Injector Prototype"

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Friday, April 17, 2009

Prof. Lois Pollack
Applied & Engineering Physics, Cornell University

 

 

"Using X-rays to Probe Light-induced Conformational Changes of Proteins"

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Friday, April 3, 2009

Prof. Richard Talman
Physics Department,
Cornell University

 

"How Best to Produce Hard Monochromatic X-rays from an Electron Beam"

Abstract:  X-ray beam production from a linac beam is investigated, especially emphasizing the optical matching flexibility that is possible with an external beam but not with a storage ring. Compared to existing storage ring light sources, a high energy linac (with or without recirculation) can produce monochromatic hard x-ray beams having comparable flux density and far higher brilliance, than are available with existing storage rings.

A dual-mode reconfiguration of CESR to exploit this capability is described. In low current, external beam mode, electrons are recirculated up to high energy (e.g. 8GeV) and used to produce very hard monochromatic (e.g. >30keV) x-rays of unprecedentedly high brilliance. In a high current, internal beam ERL mode at lower energy (e.g. 3 GeV) high flux beams of less-hard x-ray are produced.

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Friday, March 27, 2009

Prof. Antje Baeumner
Biological and Environmental Engineering,
Cornell University

"Biosensors, Microfluidics, Liposomes:  How to Best Detect Nucleic Acids and Proteins"

Abstract:  Biosensors in the format of lateral-flow assays and of microfluidic systems have been developed detecting specific nucleic acid sequences and proteins of pathogenic organisms that are present in food, the environment or that are important in clinical diagnostics. Engineering and biochemical design are used for the development of rapid and simple, yet highly specific biosensors with low limits of detection for field tests or for application in the point of care setting. The resulting lateral flow assays and microfluidic biosensors have either fluorescent or electrochemical detection, use liposomes for signal amplification and provide extremely low limits of detection in the low fmol to amol range, with yet high assay and storage stability.

Typically, pathogenic organisms are identified via their mRNA molecules to provide information of their viability status. However, also rRNA and viral RNA have been used and more recently antibody and receptor-based approaches are applied to the quantification of toxins and cell surfaces. Analytes of interest have so far included B. anthracis, C. parvum, Dengue virus, E. coli, S. pyogenes, as well as cholera toxin and CD4+ T-lymphocytes relevant in HIV/AIDS diagnostics. Signal amplification is accomplished in general using liposomes entrapping sulforhodamine B or a redox couple. Liposomes were shown to provide limits of detection orders of magnitude lower than colloidal gold, fluorescein, quantum dots and enzyme amplification strategies.

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Friday, March 13, 2009

Debashis Ghosh, Ph.D.
Senior Research Scientist,
Hauptman-Woodward Institute

 

 

"Nuts and Bolts of the Estrogen Factory"

Abstract:  The molecular details of Aromatase, the key enzyme required for the body to make estrogen, are no longer a mystery thanks to the structural biology work done by the Ghosh lab at the Hauptman-Woodward Medical Research Institute (HWI) in Buffalo, New York. Dr. Debashis Ghosh's solution of the three-dimensional structure of aromatase is the first time that scientists have been able to visualize the mechanism of synthesizing estrogen. In fact, the Ghosh lab has determined the structures of all three of the enzymes involved in controlling estrogen levels that can serve as drug targets for estrogen-dependent tumors in breast cancer. This work is so significant, the world-renowned journal Nature will be publishing the structure of aromatase at 2.90 angstrom resolution in an upcoming issue. The other two enzyme structures determined by the Ghosh lab as part of this project were estrone sulfatase (2003) and 17beta-hydroxysteroid dehydrogenase type 1 (1996). All three enzymes control the levels of estradiol in different tissues. "This is a dream come true," Dr. Debashis Ghosh, a HWI senior research scientist and a principal investigator who also holds a joint faculty appointment at the Roswell Park Cancer Institute (RPCI), said. "Scientists worldwide have been trying for 35 years to crystallize this membrane-bound enzyme and we are the first to succeed. Now that we know the structures of all three key enzymes implicated in estrogen-dependant breast cancers, our goal is to have a personalized cocktail of inhibitors customized to the specific treatment needs of each patient. Our knowledge about these three enzymes will enable us to develop three mutually exclusive inhibitors customized to each patient's needs which will work in harmony together with minimal side effects."

For more information please see:

http://www.lightsources.org/cms/?pid=1003215 http://www.nature.com/nature/journal/v457/n7226/abs/nature07614.html http://www.hwi.buffalo.edu/Newsroom/Press_Release_09/January/1_8_09.pdf

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Friday, March 6, 2009

Arthur Woll, Staff Scientist
CHESS, Cornell University

 

"Coordination-dependent Surface Atomic Contraction in Nanocrystals Revealed by Coherent [electron] Diffraction"
Huang WJ, Sun R, Tao J, Menard LD, Nuzzo RG, and Zuo JM., Nature Materials, Vol. 7, 308 (2008) http://www.nature.com/nmat/journal/v7/n4/full/nmat2132.html

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Friday, February 27, 2009

Suntao Wang, Post-doc
LASSP Department, Cornell University

 

"Making Porous Materials with Block Copolymers"

Abstract:  Block copolymers are fascinating self-assembly materials which exhibit exotic mesophases and can form ordered nanostructures. By selective removal of one component from a self-assembled block copolymer, porous materials with ordered and nanoscale pores can be generated. These nanoporous materials have shown great potential applications in nanotechnology, such as separation, filtration, catalysis, and template. Over past several decades, tremendous amount of experimental efforts have been put on making porous materials with different block copolymer using different approaches. In this talk, I will give a general introduction on how to make these porous materials. Different etching techniques, characterization tools, and future challenges will be discussed as well.

References:
(1) F.S. Bates and G.H. Fredrickson; "Block Copolymer Thermodynamics: theory and experiment", Annu. Rev. Phys. Chem. 41, 525-557 (1990)
http://arjournals.annualreviews.org/doi/abs/10.1146/annurev.pc.41.100190.002
(2) F.S. Bates and G.H. Fredrickson; "Block Copolymers, Designer Soft Materials", Physics Today 52, 32-38 (1999)
http://adsabs.harvard.edu/abs/1999PhT....52b..32B
(3) F.S. Bates; "Network Phases in Block Copolymer Melts", MRS bulletin 30, 525-532 (2005)
http://www.mrs.org/s_mrs/sec_subscribe.asp?CID=3677&DID=159567&action=detail
(4) M.A. Hillmyer; "Nanoporous Materials from Block Copolymer Precursors", Adv. Polym. Sci. 190, 137-181 (2005)
http://www.springerlink.com/content/e91mp5xq1au8kt4t/
(5) D.A. Olson, L. Chen, and M.A. Hillmyer; "Templating Nanoporous Polymers with Ordered Block Copolymers", Chem. Mater. 20, 869-890 (2008)
http://pubs.acs.org/doi/abs/10.1021/cm702239k?prevSearch=templating+nanoporo

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Friday, February 20, 2009

Prof. Don Hartill
Physics, Cornell University

 

"Prospects for the Large Hadron Collider (LHC)"

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Friday, February 13, 2009

Chae Un Kim, Research Associate
MacCHESS, Cornell University

 

"Phase Behavior of Water inside Protein Crystals"

Abstract:  Protein crystals typically consist of 40 ~ 60 % water and the internal water forms solvent channels (2 ~ 4 nm in diameter) inside the crystals. We have studied the phase behavior of water inside protein crystals using a novel crystal freezing method, high-pressure cryocooling. Using X-ray diffraction, we demonstrated that the high-density amorphous (HDA) ice induced inside the high-pressure cryocooled protein crystal undergoes a first order phase transition to low-density amorphous (LDA) ice as the crystal is warmed from 80 to 170 K. More surprisingly, we found evidence for a liquid state of water during the ice transition by analyzing the protein crystallographic data. In this talk, I will first explain the procedure of high pressure cryocooling method and then I will present the experimental results on the water confined in protein crystals.

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~NOTE: Held in 380 Wilson Lab~

Friday, February 6, 2009

Ulrich Wiesner, Spencer T. Olin Professor of Engineering
Materials Science and Engineering Department,
Cornell University

 

 

"Combining Polymer Science with Inorganic Chemistry into New Materials"

Abstract:  In the second half of the 90’s the Wiesner group successfully transferred concepts developed in the field of polymer science to structure amorphous aluminosilicates on the tens of nanometer scale.[1] By using thermodynamic principles established for block copolymers, inorganic sol-nanoparticles were structure directed into well defined morphologies. Burning out of the organic compounds resulted in nanoporous materials with ordered and uniform pores and hexagonal as well as bicontinuous cubic pore structures. In 2004 similar concepts were employed successfully to generate the first ordered nanoporous non-oxide type ceramics stable up to 1500°C from block copolymer assembly.[2] Similar approaches can be applied to crystalline oxides. Using a combination of soft and hard (CASH) chemistries approach, the Cornell team was able to directly access thermally stable and highly crystalline nanoporous transition metal oxides with uniform pores.[3] These studies have demonstrated relatively facile “one-pot” type synthesis approaches to nanostructured and nanoporous materials, a requirement that should facilitate translation of research results into industrial settings. More recently, for silica-type sols the Cornell team experimentally revealed the existence of a critical sol nanoparticle size relative to the size of the block copolymer required to obtain the desired structure control.[4] These results suggested that besides enthalpic contributions, entropy has to be carefully considered when mixing inorganic nanoparticles into block copolymers. The work further suggested that the same structure control should be obtained independent of the nature of the core of the nanoparticles, as long as corona chemistry and particle size are properly taken into account. For example, these results together with the development of particular charged ligand structures and use of the CASH method enabled synthesis of the first nanoporous Pt metal structures from block copolymer assembly in the bulk (see Figure 1).[5] The present talk will describe, and give a perspective of, these approaches for future materials development with emphasis on energy generation and storage as well as nanophotonics/plasmonics applications and will discuss the important role of scattering experiments for structural materials characterization.

Fig 1 schematic
Figure 1:  Schematic of metal
nanoparticle-block copolymer derived
nanoporous metals (pore size ~20nm)

References:
[1] M. Templin, A. Franck, A. Du Chesne, H. Leist, Y. Zhang, R. Ulrich, V. Schädler, and U. Wiesner; "Organically Modified Aluminosilicate Mesostructures from Block Copolymer Phases", Science 278, 1795-1798 (1997)

[2] M. Kamperman, C. B. W. Garcia, P. Du, H. Ow, and U. Wiesner; "Ordered Mesoporous Ceramics Stable up to 1500°C from Diblock Copolymers", J. Am. Chem. Soc. 126, 14708-14709 (2004)

[3] J. Lee, M. C. Orilall, S. C. Warren, M. Kamperman, F. J. DiSalvo, and U. Wiesner; "Direct Access to Thermally Stable and Highly Crystalline Mesoporous Transition Metal Oxides with Uniform Pores", Nature Mater. 7, 222-228 (2008)

[4] S. C. Warren, F. J. DiSalvo, and U. Wiesner; "Nanoparticle-tuned Assembly and Disassembly of Mesostructured Silica", Nature Mater. 6, 156-161 (2007)

[5] S. C. Warren, L. C. Messina, L. S. Slaughter, M. Kamperman, Q. Zhou, S. M. Gruner, F. J. DiSalvo, and U. Wiesner; "Ordered Mesoporous Materials from Metal Nanoparticle-block Copolymer Self-assembly", Science 320, 1748-1752 (2008)

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Friday, January 30, 2009

Alexander Romanenko, Ph.D.
Physics Department, Cornell University

 

"High Field Q Degradation in SRF Cavities:  hunt for the culprit"

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Friday, January 16, 2009

Xiaowei Dong
Argonne National Laboratory

 

"Simulation Study on the Mechanism of Electron Cloud Formation and Related Instabilities"

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SPECIAL Seminar  -
NOTE: Day, time, and place

Thursday, January 15, 2009
301 Wilson Lab - 4PM

Dmitry Teytelman
Dimtel, Inc.

"Measurements of the Electron Cloud Driven Instabilities in DAFNE"

Abstract:  Historically, very fast horizontal coupled-bunch instabilities have been observed in the positron ring of DAFNE. Characterization of these instabilities using a mix of old and new diagnostic techniques has allowed us to eliminate all possible sources, except for the electron cloud. I will present the above-mentioned measurement methods and illustrate them with DAFNE data.

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Friday, January 9, 2009

Maury Tigner, Director
Cornell Laboratory for Accelerator-based Sciences and Education
Cornell University

 

"CLIC, Plasmas, and all that..."

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