APS User News-at-a-Glance
Issue 32: June 29, 2005


1. Message from Murray: XOR Tactical Plan Evolves; Three Upgrades Chosen
2. Science Highlight: Sequence to Structure in DNA
3. New Technique Captures Submicrosecond Images Using White Beam; Work Garners Argonne Award
4. Operating Mode Changes Decided for Summer Run
5. Proposal Deadlines Approaching: July 15
6. Crystallographic Exposure: APS at ACA
7. Four Elected to APS Users Organization Steering Committee
8. 2005 Users Meeting: A Rich Sampling of Science Past, Present, and Future

--Briefly Noted

--Dates and Deadlines


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1. Message from Murray: XOR Tactical Plan Evolves; Three Upgrades Chosen
(Contact: Murray Gibson, jmgibson@aps.anl.gov)

The "XOR Tactical Plan" (http://www.aps.anl.gov/Future/Reports/) has been evolving in the last few months, with the benefit of a lot of input from the user community. The plan aims to provide a blueprint for the optimization of our XOR beamlines by producing dedicated and state-of-the-art capabilities for our users. We also hope that this blueprint will encourage partner users to come forward to foster some of the activities and that, with the participation of the CATs, it can become a true APS Tactical Plan. Even though we do not have the resources to execute all of the XOR plan quickly, the blueprint will guide our investments in the right direction. Most recently, we solicited general comments on the plan, and more than 100 were received. These comments can be seen at  http://www.aps.anl.gov/Future/Comments/. While the great majority of the comments are very positive, it is clear that the optimum configuration needed for a few technical areas, especially the very important field of surface and interface scattering, needs further discussion and refinement. Nonetheless, the support for our plan encourages us to go ahead with some initial steps. I am happy to announce that we have committed to move forward using our equipment funds to begin three upgrade projects from the plan. Gabrielle Long provided the following descriptions of these three beamline upgrade projects.

Beamline 1-ID. We will begin to reconfigure beamline 1-ID into a dedicated high-brilliance, high-energy x-ray beamline that will be unique in the United States and highly competitive with other high-energy x-ray sources. It will enable significant research in stress/strain mapping in engineering materials, in high-resolution powder diffraction, and in spatially resolved small-angle x-ray scattering from gradient-layered materials. By making use of the latest developments in insertion devices (e.g., superconducting undulators) and optimized optics, the APS will ultimately deliver significant gains (50 to 100 times) over what is currently available. Contact: Dean Haeffner, haeffner@aps.anl.gov.

Beamline 12-ID. We will begin the re-instrumentation of beamline 12-ID to develop independent stations dedicated to small-angle x-ray scattering (SAXS) and ultra-small-angle x-ray scattering (USAXS). Capabilities will expand to include real-time and in situ measurements of structures that are fundamental to the function of modern materials systems. In the short term, beam time available for SAXS and USAXS will increase significantly. In the longer term, when a new home can be found for the 12-ID surface and interface experiments, sector 12 will become fully dedicated to SAXS and USAXS. Contact: Mark Beno, beno@anl.gov.

Beamline 32-ID. We will take the first steps toward the realization of a dedicated full-field imaging facility on beamline 32-ID for phase-contrast imaging, topography, tomography, and USAXS imaging. X-ray imaging is key to the investigation of nano- and microstructures to address issues such as fracture mechanics of composites and biological materials, materials microstructure/properties research, small animal and soft tissue physiology, the internal structures of micro-devices, electronic components and packaging, characterization of geological structures and microfossils, cement mortar research, structure and development of foams, and the granular packing of nonequilibrium systems. Contact: Qun Shen, qshen@aps.anl.gov


2. Science Highlight: Sequence to Structure in DNA
(Contact: P. Shing Ho, hops@onid.orst.edu)

Oregon State University researchers working at the BioCARS facility (sector 14) at the APS and at the Advanced Light Source (Lawrence Berkeley Laboratory) "have used X-ray crystallography to determine the three-dimensional structures of nearly all the possible sequences of a macromolecule, and thereby create a map of DNA structure," according to a press release issued by Oregon State University. The researchers note that understanding genetic structure is just as important as the understanding of genetic sequence that is gained through genome research. The possible structures represent three structural classes of DNA and include some conformations that bridge these classes. The resulting data set can show structural differences resulting from changing a single nucleotide in the sequence. These structural differences can now be examined for possible functional roles, for example, regulating gene expression.

F.A. Hays et al., "How sequence defines structure: A crystallographic map of DNA structure and conformation," Proc. Nat. Acad. Sci. 102 (20), 7157 (2005).

3. New Technique Captures Submicrosecond Images Using White Beam; Work Garners Argonne Award
(Contact: Jin Wang, wangj@aps.anl.gov, and Wah-Keat Lee, wklee@aps.anl.gov)

APS scientists Jin Wang and Wah-Keat Lee have developed a technique using phase-contrast methods to make images using the APS white beam with exposure times on the order of submicroseconds. This imaging technique has many possible applications, and it is expected to have a significant impact on a variety of scientific areas. For example, this novel method was used to image the micromotion of a pintle (plunger) behind a 200-µm orifice enclosed in a millimeters-thick steel injector housing. The images were taken in real time during a submillisecond injection process. The results from these novel experiments allow the correlation of in-nozzle pintle motion with out-of-nozzle jet flow and spray formation, and they provide a wealth of information that can be used to design more effective nozzles. The white-beam, phase-contrast imaging technique has many possible applications, and it is expected to have a significant impact on a variety of scientific areas.

On June 16, Wang and Lee received a 2005 Distinguished Performance Award from the University of Chicago Board of Governors for Argonne National Laboratory. The award recognizes outstanding scientific or technical achievements, in this case Wang and Lee's pioneering new applications of synchrotron x-rays. Their work has opened many new avenues for APS users.

Dr. Wang and Dr. Lee (both in the Experimental Facilities Division) joined the Laboratory in 1995, and 1990, respectively. Jin Wang is a world-renowned expert in the application of x-ray scattering to a wide variety of problems in materials science problems. He is best known for his research into the dynamics of fuel sprays, where he applied an innovative research approach and achieved absolutely unique results. Wah-Keat Lee, after many years of developing successful high-heat load x-ray optics, switched fields and became an expert in phase-contrast x-ray imaging. The results of his "in-vivo" imaging of breathing insects have been acclaimed worldwide. The two scientists currently collaborate on projects that use their combined expertise to great effect, such as the white-beam imaging technique.


4. Operating Mode Changes Decided for Summer Run
(Contact: John Quintana, jpq@aps.anl.gov)

The APS Operations Directorate, after discussions with beamline staff in April, made two changes in operating modes, one of which is permanent.

1. The hybrid mode (Mode 1) has been redefined to allow an increased current in the single bunch used for timing experiments; thus, experimenters using the timing aspects of the hybrid mode will benefit from increased flux. APS has found that the timing bunch current can be increased to 12 mA, but the top-up interval must be reduced from two minutes to one minute to support this current. Another consequence is that the 12-mA timing bunch will decay faster than the previous 8-mA bunch. The one-minute top-up interval will now be a permanent feature of the hybrid fill mode. The top-up interval is unchanged in other modes.

2. To further exploit the usefulness of top-up mode, which has had a large impact on facilities operations, the first week of Run 2005-2 was converted to this mode.

In Issue 31 of User News, we reported another change for August: The interval August 9 to August 15 will be run in 24-singlet top-up mode (low emittance). "Higher current" operation had previously been propoed for this interval.

The Operations Directorate, which meets weekly, consists of Murray Gibson (Associate Laboratory Director), Dennis Mills (Deputy Associate Laboratory Director), John Quintana (Associate Division Director for Operations), the three APS division directors (Rod Gerig, ASD; Efim Gluskin, XFD; and Bill Ruzicka, AOD), and designated representatives from the Partner User Council and the APS Users Organization (currently, Paul Zschack and Mark Rivers, respectively).

Current schedule:
Revised fill pattern descriptions:
Upcoming schedule (Run 2005-3):

5. Proposal Deadlines Approaching: July 15

Proposals for APS General User and Partner User beam time are due July 15 for experiments in the 2005-3 cycle (October 4 to December 21, 2005). General User proposals will be reviewed on August 4 and the allocation committees will meet on August 18.

July 15 is also the deadline for the third call for early-access proposals for the Center for Nanoscale Materials. (Note change from deadline reported in issue 31 of User News.) Please note that if a proposed CNM project involves General User access to the APS, an APS proposal must be submitted as well.

Many x-ray users are finding that neutron studies complement their work at APS, and vice versa. Unfortunately, a proposal deadline at Argonne's Intense Pulsed Neutron Source has just passed. The next deadline is November 15 for work to be performed between February 14 and June 15, 2006.

APS: Contact: Elane Streets, estreets@aps.anl.gov. Policies and guidance: http://www.aps.anl.gov/Users/Scientific_Access/. Proposal system: http://beam.aps.anl.gov/pls/apsweb/gup0005.start_page

CNM: Contact: Jill Morgenthaler, jill@anl.gov. Policies and guidance: http://nano.anl.gov

IPNS: Contact: Maria Heinig, mheinig@anl.gov. Facility and proposal process: http://www.pns.anl.gov/proposalcall/.

6. Crystallographic Exposure: APS at ACA
(Contact: Elane Streets, estreets@aps.anl.gov)

The APS partnered with GM/CA-CAT and SGX-CAT to exhibit at the 2005 American Crystallography Association Meeting held May 28 to June 2 in Orlando, Florida. Other APS sectors that support crystallography also participated. We hope you had a chance to stop by and say hello!

7. Four Elected to APS Users Organization Steering Committee
(Contact: Susan Strasser, strasser@aps.anl.gov)

In an election held in conjunction with the Users Meeting, users elected four new members to the APS Users Organization Steering Committee. The new members are, in alphabetical order, Simon Billinge, a professor at Michigan State with interests in condensed matter physics; Millie Firestone, a chemist at Argonne National Laboratory working with soft materials, nanostructures, and biomembranes; Barbara Golden, an associate professor of biochemistry at Purdue, specializing in RNA; and David Reis, an assistant professor at University of Michigan, whose interests include the physics of ultrafast x-ray scattering. The new incumbents will serve for three years. Carol Thompson assumes leadership of the committee, and Mark Rivers continues, ex officio, as the past president.

The only outgoing member was past president Steve Durbin. The committee currently has 14 members, as a consequence of the transition to annual elections, which began in 2003. The 2006 election will complete the transition, with six members rotating off and four being elected, so that the committee will return to its steady state of 12 members. More information on the committee and its members is at

8. 2005 Users Meeting: A Rich Sampling of Science Past, Present, and Future
(Contact: Susan Strasser, strasser@aps.anl.gov)

The 2005 Users Meeting was in every way a celebration of science: past, present, and future! Highlights included a retrospective look by David Moncton on the impact of the APS on current and future synchrotron sources; insights from Senator Dick Durbin of Illinois (the Senate Minority Whip) on Washington's view of current funding for science; and the cornerstone ceremony for the Center for Nanoscale Materials (Argonne's newest user facility) attended by Secretary of Energy Samuel W. Bodman and Illinois Governor Rod Blagojevich.

Attendees for the week-long event were able to hear outstanding science talks, view more than 140 posters, choose among nine half- or full-day workshops, and attend a number of social functions, including the traditional mid-week banquet--a "Celebration of Light" commemorating the tenth anniversary of first light at the APS and the first light on the nanoprobe beamline (achieved in early March). For those unable to attend, a limited number of program books are available on request; please write to apsuser@aps.anl.gov.

For the second year, the week's events began with a day focused on the Center for Nanoscale Materials (CNM), with science talks, a poster session, a reception, and dinner. Tuesday's agenda included three joint APS/CNM workshops: "Nanoscale Bio-Hybrid Materials," "Advanced Nanopatterning," and " Scientific Applications of the Hard X-ray Nanoprobe." (Summaries of several workshops are given at the end of this issue.)

Wednesday's focus was on the APS. The morning began with news from Washington (delivered by Senator Durbin and Pedro Montano from DOE/Basic Energy Sciences), followed by update presentations from APS Director Murray Gibson and CNM Director Eric Isaacs. Also included was the presentation of the prestigious APS Compton Award to Günter Schmahl and Janos Kirz for pioneering work in the field of x-ray microscopy using Fresnel zone plates. Concluding the morning session was a talk by David Moncton commemorating the tenth anniversary. Wednesday afternoon was a sampler of APS science, with talks by Simon Bare ("Uniform Catalytic Site in Sn-beta Zeolite Determined Using X-ray Absorption Fine Structure"), Peggy O'Day ("It's Not As Easy As It Looks: Application of Synchrotron-Based Techniques to the Analysis of Environmental Contaminants"), Brian Newbury ("The APS and Archaeometallurgy: Studying the Alloys and Forming Techniques of the Medieval Brass Industry"), and Alfonso Mondragon ("Structural Studies of Catalytic RNA Molecules"). A poster session and "Celebration of Light" banquet rounded out the day. (See photo gallery to get a flavor of the week's events.)

Thursday morning's continuation of the APS science sampler included talks by Peter Abbamonte ("Imaging Electronic Motion in Water with Attosecond Time Resolution"), Michael Borland ("A Survey of Possible Near-Term Accelerator Improvements"), and Aled Edwards ("Structural Biology and Genomes.) The announcement of student poster prize winners (Jeremy Robinson from UC Berkeley for "Metal-Induced Assembly of a Semiconductor-Island Lattice: Ge Islands on Au-Patterned Si"; Anthony Escuadro of Northwestern U. for "XSW Imaging of Submonolayer Vanadium Oxides on alpha-Fe 2 O 3 (0001)"; and Marcus Young of Northwestern U. for "Internal Strain Measurements in Ultrahigh-Carbon Steels"), and newly elected APS Users Organization Steering Committee members (see preceding story) concluded the morning.

The parade of workshops continued on Thursday afternoon with the first sessions of "The Art of Collecting Good Diffraction Data" and " Scattering from Liquid Surfaces and Interfaces." (The concluding sessions of these two workshops were held on Friday morning.) The two additional workshops on Thursday afternoon were " Metals and Metalloids in Cell Biology" and "Deep X-ray Lithography and LIGA."

Users Meeting week ended on an extremely high note with the placing of seals in the cornerstone for the Center for Nanoscale Materials on Friday morning. Master of Ceremonies Robert Rosner, Director of Argonne National Laboratory, welcomed the 100 or so invited guests, then introduced Don Randel (President, The University of Chicago), Raymond Orbach (Director, Office of Science, DOE), The Honorable Judy Biggert (Congresswoman, U.S. Congress, Illinois District 13), The Honorable Rod Blagojevich (Governor, State of Illinois), and The Honorable Samuel Bodman (Secretary of Energy, U.S. Department of Energy), each of whom spoke briefly and offered congratulations to the project team. Following the ceremony, Secretary Bodman toured parts of the APS. The Secretary's visit concluded with an "all-hands" meeting with Argonne employees. More details about the ceremony are at http://www.anl.gov/news-room/News/2005/news050506.html.

The remainder of on Friday was also forward-looking with the final workshops, " Applications of Grazing Incidence Small-Angle X-ray Scattering" and "Generation and User of Short X-ray Pulses at the APS."

The meeting web site is http://www.aps.anl.gov/Users/Meeting/2005/.


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-- Neutron macromolecular crystallography conference at SNS
A conference entitled "Frontiers of Neutron Macromolecular Crystallography at the SNS" will be held at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory on July 12-13, 2005. Registration information is at http://www.sns.gov/mandi2005/.

The Conference will focus on the role of hydrogen atoms in biological structure and function and will highlight the contributions that next-generation neutron macromolecular crystallography instruments can make in defining accurate hydrogen atom positions, protonation states, and hydration states in biological macromolecules.  A limited number of scholarships will be available to support young researchers to attend the meeting.

-- Interested in Surfaces and Interfaces? Mark Your Calendars for September
APS users are organizing a workshop on " In situ Characterization of Surface and Interface Structures and Processes," to be held September 8-9, 2005, at the Advanced Photon Source. Paul Zschack, Paul Fenter, and Paul Fuoss are the local organizing committee. Further details will be provided in a future issue.

-- Synchrotron Environmental Science III to be held September 19-21 at Brookhaven
SES III will bring together the diverse community of scientists who apply synchrotron-based radiation techniques to study the biological and geochemical aspects of both local and global environmental issues. Environmental science researchers new to synchrotron radiation are encouraged to attend. Contributed talks are due July 15; poster abstracts and preregistration are due August 5. For more information, see http://www.cems.stonybrook.edu/ses-iii.

-- Pittsburgh Diffraction Conference, November 3-5 at Argonne
The 63rd Pittsburgh Diffraction Conference will be held at Argonne National Laboratory on November 3-5, 2005. It will be hosted by the Intense Pulsed Neutron Source (IPNS) and will feature a full-day session on frontiers in neutron scattering, as well as tours of the IPNS and APS. Details will be forthcoming at this site: http://www.pittdifsoc.org/63rd_PDS_announce.htm.

-- Just Finished Your Dissertation?? Send Us the Info!
First of all, congratulations! When you've recovered (from the work--and/or the party!), please send us the details (of the dissertation, not the party) so we can add it to our publication database. Send the following information to Marlene Nowartowski (nova@aps.anl.gov): your name, the title of the dissertation, the institution awarding it, the year, the degree (Ph.D. or master's), and--very important!--the beamline(s) and sector(s) where you did the work.


Regularly scheduled technical meetings -- http://www.aps.anl.gov/News/Meetings/
Proposal system -- http://beam.aps.anl.gov/pls/apsweb/gup0005.start_page
Ops. Monthly meetings -- http://www.aps.anl.gov/News/Meetings/Monthly_Meetings/
User calendar (admin. meetings, reviews) -- http://www.aps.anl.gov/Users/General_Reference/Calendar/

*New entry since last issue

July 1 Application deadline, crystallography summer school
July 13 APS/Users' Operations Monthly Meeting
July 14 APSUO Steering Committee Meeting
*July 15 General User and Partner User proposals due
*July 15 CNM proposals due
July 15 Partner User Council Meeting
July 18 - 30 Crystallography summer school
July 26 - 29 XAFS summer school
*August 8 Proposal Review Panels meet
August 14 - 28 Neutron & x-ray summer school
*August 17

APS/Users' Operations Monthly Meeting

*August 18

Beamtime Allocation Committees meet

August 25 End of Run 2005-2
*September 14 APS/Users' Operations Monthly Meeting
September 15 Review - Sector 9 (CMC/XOR)
September 16 Review - Sector 6 (MU-CAT)
*October 4 Start of Run 2005-3
October 17 Review - Sector 5 (DND-CAT)
October 18 Review - Sector 8-BM and 24 (NE-CAT)
October 27 APSUO Steering Committee Meeting
October 28 Partner User Council Meeting
*December 21 End of Run 2005-3
*January 24-26 Scientific Advisory Committee meetin
*January 25 Cross-Cut Review meeting (topic TBD)
May 1-6 2006 Users Meeting
*May 7-11 2007 Users Meeting




2005 APS/CNM Users Meeting Summary
Workshop 3: Scientific Applications of the Hard X-ray Nanoprobe
Organized by Jörg Maser (maser@aps.anl.gov), Brian Stephenson, Paul Evans

The workshop on "Scientific Applications of the Hard X-ray Nanoprobe" highlighted the rapidly evolving impact of hard x-ray nanoprobes and x-ray microscopy. Developments around the world in this area have resulted in dramatic improvements in x-ray optics and instrumentation and a variety of new scientific techniques. Shigeru Kimura of SPring-8 and Jean Susini of the European Synchrotron Radiation Facility described major nanoprobe initiatives at those facilities, including x-ray optics developments that have yielded spot sizes of 30 nm. The CNM/APS X-ray Nanoprobe, discussed by Jörg Maser, will be a unique user facility allowing widespread access to both focused-beam and full-field imaging approaches to microscopy. The wide potential of these emerging tools was demonstrated in a series of scientific presentations that ranged from biological applications to materials sciences. They included nanometer-scale imaging based on the inversion of coherent diffraction patterns (Ian Robinson, U. of Illinois), the integration of semiconducting nanoparticles in biological systems (Gayle Woloschak, Northwestern U. and Tijana Rajh, Argonne), and novel uses of the unique time structure and structural and magnetic sensitivity of hard x-ray synchrotron radiation (Cev Noyan, Columbia U.; Martin Holt, APS; Carol Thompson, Northern Illinois U.; Paul Evans, U. of Wisconsin; and George Srajer, APS). The workshop as a whole reflected the continuing scientific impact of the work of Janos Kirz and Günter Schmahl, who were presented with the Compton Award at the APS User Meeting.


2005 APS/CNM Users Meeting Summary
Workshop 5: Scattering from Liquid Surfaces and Interfaces
Organized by Binhua Lin (lin@cars.uchicago.edu), Ivan Kuzmenko

The Liquid Surface Workshop held at the 2005 APS User Meeting impressively demonstrated the broad scope of important and fundamental scientific problems related to liquid interfaces. Scientific topics included surface layering and in-plane structure of liquid metals and some other liquids (P. Pershan, Harvard U., and S.A. Rice, U. of Chicago), studies of fluctuations on thin films of polymer melts (S. Sinha, Los Alamos and M. Rafailovich, SUNY Stony Brook ), high-energy X-ray studies of buried organic films (molecular junctions) at silicon-mercury interface (B. Ocko, BNL) dynamics of liquid-liquid interfaces (M. Schlossman, U. of Illinois at Chicago, and I. Benjamin, UCSC), structure of inorganic films on liquids (P. Dutta, Northwestern U. and E. Dimasi, BNL), studies of cholesterol/phospholipids interactions in biologically relevant films (K.Y.C. Lee, U. of Chicago) and of amphiphilic 4-helix bundle peptides (J. Strzalka, U. of Pennsylvania) A significant portion of the experiments reported at the workshop were carried out at APS.


2005 APS/CNM Users Meeting Summary
Workshop 6: Metals and Metalloids in Cell Biology
Organized Gayle Woloschak (g-woloschak@northwestern.edu), Dina F. Mandoli

Metals and metalloids are essential co-factors in many proteins and correlate with disease states. Not surprisingly then, superoptimal or suboptimal metal levels in the environment are problematic. The workshop opened with an overview of methods, in particular, hard x-ray fluorescence microscopy (Stefan Vogt, Barry Lai, Jörg Maser) and ways of integrating x-ray techniques with other kinds of microscopy (Peter Ingram). Koichi Iwasaki discussed metal and metalloid homeostasis in ion channels in C. elegans, a worm. Defects in magnesium regulation cause sterility in both worms and humans and also mediate nickel toxicity in the worm. David Eide uses molecular genetics and molecular biology to study the genes and gene products that regulate all aspects of zinc metabolism. Gayle Woloshak discussed the uses of TiO 2 -DNA nanocomposites in mammalian cells. Imaging shows that specific DNA sequences can be cleaved and that these nanocomposites can be loaded into nuclei. Dina F. Mandoli reported that, using XANES and XAFS at APS, they have been able to quantify and localize arsenicals to specific subcellular regions in Acetabularia acetabulum, a giant uninucleate, unicellular model system. Mary Corbett described an elegant application of x-ray absorption spectroscopy to probe metalocluster biosynthesis in a portion of the nitrogenase complex. Benjamin Twining has used x-ray fluorescence to visualize iron within algae taken from the water column in the Southern Ocean Iron Experiment (SoFeX) to reveal the environmental and ecological consequences of iron availability in the Earth's oceans.


2005 APS/CNM Users Meeting Summary
Workshop 8: Applications of Grazing-incidence Small-angle X-ray Scattering
Organized by Jin Wang (wangj@aps.anl.gov), Randall Winans

As an increasingly important structural-characterization technique, grazing-incidence small-angle scattering (GISAXS) finds vast application in nanostructures and nanocomposites at surfaces and interfaces. Most significantly, as a complementary method to conventional surface-sensitive tools such as scanning probe microscopy and electron microscopy, GISAXS can be used in situ and in real time to monitor the formation of the nanostructure or nanocomposite, which makes it most suitable for studying the kinetics of nanoassembly processes. This workshop focused on the applications of GISAXS and the current technical capability at the APS to support general users in this area. To better help current and potential APS users to integrate GISAXS experiments in their research, Jin Wang of the APS and Randall Winans of Argonne's Chemistry Division organized this workshop as a part of the 2005 Users Meeting for the Advanced Photon Source and the Center for Nanoscale Materials.

The half-day workshop started promptly at 8:30 on Friday morning, the last day of the Users Meeting. Seven speakers from universities, national labs, and government research institutes were invited to present their research experience with GISAXS and their visions on future applications of the technique. Among the speakers, two were beamline scientists who gave tutorial-style presentations to illustrate methods for quantitatively analyzing GISAXS data collected from samples with buried structures.

Professor Edward Kramer (University of California, Santa Barbara) opened the workshop with a highlight presentation titled "The Science and Technology of Self-Assembly of Block Copolymer Thin Films." Ordered block copolymer thin films now hold great potential for use as templates for nanolithography on length scales well below those of current optical lithography. Through years of research, it is now possible to produce two-dimensionally (2D) ordered nanostructure in crystalline form on an entire substrate wafer. These structures will have great potential in applications of high-density data storage, gate structures in memory devices, and spintronics. Interesting scientific and practical problems involved in the nanoassembling process can be effectively probed by surface-sensitive x-ray techniques such as GISAXS in a nondestructive fashion.

Dr. Ben Ocko, a physicist from Brookhaven National Laboratory (BNL) gave a talk on the current GISAXS activities at X22B beamline at the National Synchrotron Light Source in BNL. He described the GISAXS studies of nanoscale liquids and block copolymer thin films on nanostructured and flat substrates. One of the distinct advantages of using GISAXS is that the samples can be under both equilibrium and nonequilibrium conditions due to the temporal resolution afforded by the method and the ability to maintain a flexible sample environment. One of the examples is highly time-resolved: block copolymers can become much more ordered during the solvent evaporation with a small amount of salt, which induces changes in the ordering behavior, leading to defect-free and large crystalline domains.

Mr. Yao Lin, a senior graduate student from Professor Tom Russell's group at the University of Massachusetts, gave a talk on using nanoparticles to change block copolymer phase and ordering behaviors. By integrating nanoparticles into the copolymer matrix, the interactions between self-organizing particles and the self-assembling matrix materials can lead to hierarchically ordered structure that can not be accessed without the nanoparticles. This has also been demonstrated with bionanoparticles. GISAXS, as well as scanning force and electron microscopic techniques, has provided the much needed tools to gain insight into the nature of the self-assembly processes.

Dr. Dong-Ryeol Lee, a physicist at the APS, presented a detailed method using distorted-wave Born approximation (DWBA) to analyze GISAXS data obtained from buried nanoparticles diffusing in polymer thin films. The quantitative analysis of the GISAXS data has been difficult. Only recently, the application of the DWBA method has made such analysis possible. The breakthrough will have a great impact on the application of GISAXS to complex nanostructures. As the analysis method continues to be a challenge, more effort will be spent on scattering theory in the grazing-incidence geometry.

The next group of speakers shifted gears to GISAXS applications in nonpolymeric samples. In the spirit of the workshop, Dr. Wen-li Wu, a chief scientist from National Institute of Standards and Technology, presented several challenging cases in the application of GISAXS to characterize supported nanoporous films. The rich phase behavior of the nanoporous materials in thin films can make remarkable but difficult scattering patterns that cannot readily be understood. Echoing the previous speakers, his talk highlighted the complexity of GISAXS analysis.

Dr. David Babonneau from Université de Poitiers of France , gave a presentation discussing three examples of GISAXS applications in materials research. The materials include nanostructures buried in thin films and ion-implanted layers: analysis of metallic nanoclusters, encapsulated in a host matrix; self-organized C/FePt granular multilayer studied during annealing; and nanocavities and defects induced by helium implantation in silicon. We observed that the utility of GISAXS to study hard condensed matter surfaces is far ahead of that in the United States.

The last talk was given by Dr. Byeongdu Lee, from the APS. In his talk, he demonstrated that anomalous GISAXS (AGISAXS) is a powerful method to analyze and interpret GISAXS patterns containing mixed scattering from surface roughness and from supported Pt particles down to the sub-nanometer scale. Particle scattering is well separated from that of surface roughness, as well as from particle fluorescence . The background free particle scattering intensities obtained by the anomalous technique can then fitted to models with DWBA-based theory. This approach is useful for in situ studies on the reactivity of very small metal clusters (5 - 300) atoms.

This workshop benefited from a lively discussion session after all the informative and interesting talks. The discussion focused on what the current challenges are with the GISAXS method and applications, such as scattering theory, coherence of the x-ray beam, and data analysis. One point raised at the workshop is that this technique can be a double-edged sword: the scattering patterns contain as much information as 3D holography, while the samples behave as the beam optics so the analysis can be very complex to obtain all the quantitative information on the nanostructure. While the challenges require a coordinated effort in the synchrotron community to solved, the discussion identified that there are urgent needs in developing a theoretical framework for streamlined data analysis procedures as well as dedicated GISAXS beamlines at the APS for better user access to this novel technique, especially in this age of nanoscience and nanotechnology. The latter need was partially addressed by a newly installed dedicated GISAXS beamline at the Sector 8ID E-station. The workshop concluded with a tour to several APS GISAXS facilities at 1BM, 8ID, and 12ID beamlines. Despite the being held on the last day of the users meeting and the constantly changing workshop schedule due to some special events, the attendance was more than 40 during most of the workshop, which shows the great enthusiasm from the user community.


2005 APS/CNM Users Meeting Summary
Workshop 9: Generation and Use of Short X-ray Pulses at APS
Organized by K.-J. Kim and D. M. Mills

The purpose of this workshop was to present preliminary results of accelerator and optics calculations to produce short (approx. 1 ps) x-ray pulses from the APS storage ring. In addition to the presentations pertaining to the generation of short pulses, a presentation summarizing the science driving this project was also made. National and international experts were invited to listen to the presentations and provide critical comments regarding all aspects of our proposal.

The basic element of the short-pulse production scheme is a pair of special RF cavities at both ends of a section of the APS ring. The first cavity imparts a position-dependent, vertical deflection (chirp) to the APS bunches, while the second cavity cancels the chirp. X-ray pulses from undulators between the deflecting cavities can then be compressed by special x-ray optics. The design of the short pulse system is constrained by the requirement that the beam property degradation in the rest of the APS ring (due to an imperfect cancellation of the deflection) be at an acceptable level. Extensive beam dynamics and optics studies have shown that the APS pulses can be shortened to 1-2 ps by this scheme.

Coming into this workshop a considerable effort had already been expended on a scheme where the RF cavity was envisioned to be operated in a CW mode so that when energized it would chirp all the bunches in the storage ring between the two cavities. Such a CW system (due to power requirements) would almost certainly be based on a superconducting radio frequency (SCRF) cavity. SCRF technology has seen a tremendous progress recently; however, an SCRF cavity for transverse chirp is more challenging due to the need to remove the lower-order modes (LOMs) as well as the higher-order modes.

A suggestion was brought to our attention that a pulsed, room-temperature cavity may also be consistent with the needs of the users since in many (but not all) cases, a laser is used as the pump beam for pump/probe experiments and lasers with adequate power typically have repetition rates of a few kilohertz (or perhaps a few tens of kilohertz at the maximum). In addition, a pulsed system may provide a larger chirp to the beam (yet to be determined) that might be of value for making the compression optics easier. Therefore, if a room-temperature cavity can be implemented more quickly, this may be an interesting short-term solution. Clearly more work is required to sort out the RT cavity options and to more carefully weigh the advantages and disadvantages of the warm cavity over a superconducting cavity.

Another concern brought forth at the workshop was that of focusing the centimeter-sized (in the vertical) chirped x-ray beam. Since high-speed mechanical choppers are often used to isolate a single x-ray pulse from the pulse-train of x-rays, small beams are needed--from 1 to 0.050 millimeters--depending on the required opening and closing time of the chopper window. While 1-millimeter-sized focal spots seemed achievable and would probably be compatible with isolating the lone bunch in our hybrid filling mode, beams of less than 100 microns for choppers that might be used in 24-bunch mode would be necessary.

In conclusion, a special insertion at the APS for 1-2 ps x-ray pulses is feasible and offers unprecedented opportunities for probing picosecond dynamics. The next step will be to decide whether an SCRF or an RT cavity will be adopted, as well as other parameters such as cavity frequency, gradient, and number of the APS sectors to be included