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Structural studies of intercalants

Description: The structure of stage 2 potassium intercalated graphite, KC/sub 24/, is discussed in both the ordered and disordered phases. A one-dimensional model is used to illustrate the qualitative features of the KC/sub 24/ diffraction patterns.
Date: January 1, 1981
Creator: Hastings, J.B.
Partner: UNT Libraries Government Documents Department

X-ray Free-electron Lasers

Description: In a free-electron laser (FEL) the lasing medium is a high-energy beam of electrons flying with relativistic speed through a periodic magnetic field. The interaction between the synchrotron radiation that is produced and the electrons in the beam induces a periodic bunching of the electrons, greatly increasing the intensity of radiation produced at a particular wavelength. Depending only on a phase match between the electron energy and the magnetic period, the wavelength of the FEL radiation can be continuously tuned within a wide spectral range. The FEL concept can be adapted to produce radiation wavelengths from millimeters to Angstroms, and can in principle produce hard x-ray beams with unprecedented peak brightness, exceeding that of the brightest synchrotron source by ten orders of magnitude or more. This paper focuses on short-wavelength FELs. It reviews the physics and characteristic properties of single-pass FELs, as well as current technical developments aiming for fully coherent x-ray radiation pulses with pulse durations in the 100 fs to 100 as range. First experimental results at wavelengths around 100 nm and examples of scientific applications planned on the new, emerging x-ray FEL facilities are presented.
Date: February 23, 2007
Creator: Feldhaus, J.; /DESY; Arthur, J.; Hastings, J.B. & /SLAC
Partner: UNT Libraries Government Documents Department

National synchrotron light source. Activity report, October 1, 1995--September 30, 1996

Description: The hard work done by the synchrotron radiation community, in collaboration with all those using large-scale central facilities during 1995, paid off in FY 1996 through the DOE`s Presidential Scientific Facilities Initiative. In comparison with the other DOE synchrotron radiation facilities, the National Synchrotron Light Source benefited least in operating budgets because it was unable to increase running time beyond 100%-nevertheless, the number of station hours was maintained. The major thrust at Brookhaven came from a 15% increase in budget which allowed the recruitment of seven staff in the beamlines support group and permitted a step increment in the funding of the extremely long list of upgrades; both to the sources and to the beamlines. During the December 1995 shutdown, the VUV Ring quadrant around U10-U12 was totally reconstructed. New front ends, enabling apertures up to 90 mrad on U10 and U12, were installed. During the year new PRTs were in formation for the infrared beamlines, encouraged by the investment the lab was able to commit from the initiative funds and by awards from the Scientific Facilities Initiative. A new PRT, specifically for small and wide angle x-ray scattering from polymers, will start work on X27C in FY 1997 and existing PRTs on X26C and X9B working on macromolecular crystallography will be joined by new members. Plans to replace aging radio frequency cavities by an improved design, originally a painfully slow six or eight year project, were brought forward so that the first pair of cavities (half of the project for the X-Ray Ring) will now be installed in FY 1997. Current upgrades to 350 mA initially and to 438 mA later in the X-Ray Ring were set aside due to lack of funds for the necessary thermally robust beryllium windows. The Scientific Facilities Initiative allowed purchase of all 34 ...
Date: May 1, 1997
Creator: Rothman, E.Z. & Hastings, J.B.
Partner: UNT Libraries Government Documents Department

In vacuum undulator task force report

Description: Historically the NSLS has been active in R&D for state-of-the-art electron beams, photon beams and x-ray optics. One of the available straight sections has therefore been dedicated to insertion device R&D. Over the past five to seven years a program aimed at exploiting the very small vertical {beta} function in the straight sections has yielded first a prototype small gap undulator (PSGU) and then an in-vacuum undulator (IVUN). The IVUN sources attain a brightness similar to the existing hybrid wigglers in X21 and X25. They radiate significantly lower total power than the wigglers but produce higher power densities. They provide undulator rather than wiggler spectra. Because of the small gaps and small periods there is not much tunability in these devices and they will have to be purpose-built for a specific scientific program. The original IVUN parameters were chosen for in-elastic x-ray scattering, similar to the scientific program on X21. This put the fundamental at 4.6 keV and the third harmonic at 13.8 keV. The question that this new possible insertion device poses is what science programs can best take advantage of this new insertion device source? To answer this, a task force was formed by M. Hart, NSLS Department Chair and charged with identifying viable scientific programs that could seek outside funding to construct IVUN beamlines. The task force concentrated on experimental programs that are presently being pursued on new insertion devices worldwide. For example, x-ray photon correlation spectroscopy, which takes advantage of the large coherent flux from undulator sources, was considered. However, this program was not considered as the highest priority. The general area of protein crystallography, however, is ideal for the IVUN source. The unique electron beam optics that makes the IVUN possible in the first place also makes the IVUN ideal as a source for microdiffraction.
Date: June 1, 1998
Creator: Hastings, J.B.; Kao, C.C. & Stefan, P.
Partner: UNT Libraries Government Documents Department

Recent advances in soft x-ray scattering instrumentation at the national synchrotron light source

Description: For the study of condensed matter systems x-ray scattering experiments are often the best choice as they have several desirable features including complete conservation of momentum in the incident and detected particles, well characterized initial and final electronic states, and insensitivity of photon transport to external electric and magnetic fields (as compared to photoelectrons for example). To extend these techniques to the soft x-ray region ({Dirac h}v < 1keV) the lack of suitable detectors, and the difficulties associated with performing scattering experiments in vacuum must be overcome. In this paper we provide details of our instrumental development program, and show some representative examples of experiments we have performed to date. 7 refs., 4 figs.
Date: January 1, 1991
Creator: Johnson, E.D.; Kao, Chi-Chang & Hastings, J.B.
Partner: UNT Libraries Government Documents Department

Optical design and performance of the X25 hybrid wiggler beam line at the NSLS

Description: The X25 beam line at the National Synchrotron Light Source (NSLS) began full-power commissioning in 1990. It extracts radiation from a 27 pole hybrid wiggler, which produces up to 1.8 kW of total power with a peak horizontal density of 450 W/mrad and critical energy of 4.6 keV. The design and performance of the beam line optics are described, in particular the cooling of the first monochromator crystal. 28 refs., 5 figs.
Date: January 1, 1991
Creator: Berman, L.E.; Hastings, J.B.; Oversluizen, T. & Woodle, M.
Partner: UNT Libraries Government Documents Department

Surface extended x-ray absorption fine structure of low-Z absorbates using fluorescence detection

Description: Comparison of x-ray fluorescence yield (FY) and electron yield surface extended x-ray absorption fine structure spectra above the S K-edge for c(2 x 2) S on Ni(100) reveals an order of magnitude higher sensitivity of the FY technique. Using FY detection, thiophene (C/sub 4/H/sub 4/S) chemisorption on Ni(100) is studied with S coverages down to 0.08 monolayer. The molecule dissociates at temperatures as low as 100K by interaction with fourfold hollow Ni sites. Blocking of these sites by oxygen leaves the molecule intact.
Date: May 1, 1985
Creator: Stoehr, J.; Kollin, E.B.; Fischer, D.A.; Hastings, J.B.; Zaera, F. & Sette, F.
Partner: UNT Libraries Government Documents Department

X-ray monochromator geometry for focusing synchrotron radiation above 10 keV

Description: The relative merits of crystals versus mirrors for focusing synchrotron radiation at energies above 10 keV are explored. As mirrors have critical angles of reflection typically 1/20 of the Bragg scattering angles for crystals, large mirror surface areas are required. Sagittal focusing is weak for mirrors and limits the amount of radiation intercepted. Crystals bent to a simple cylindrical curvature are shown to accept large divergences of radiation for sagittal focusing. At a magnification near 1/3, the cylindrically curved crystals are shown to make the proper Bragg angle for energies above 5 keV and for divergences larger than 10 mrad and to produce x-ray beams which are approximately focused.
Date: January 1, 1979
Creator: Sparks, C.J. Jr.; Borie, B.S. & Hastings, J.B.
Partner: UNT Libraries Government Documents Department

Report from the NSLS workshop: Sources and applications of high intensity uv-vuv light

Description: A workshop was held to evaluate sources and applications of high intensity, ultra violet (UV) radiation for biological, chemical, and materials sciences. The proposed sources are a UV free electron laser (FEL) driven by a high brightness linac and undulators in long, straight sections of a specially designed low energy (400 MeV) storage ring. These two distinct types of sources will provide a broad range of scientific opportunities that were discussed in detail during the workshop.
Date: January 1, 1990
Creator: Johnson, E.D. & Hastings, J.B. (eds.)
Partner: UNT Libraries Government Documents Department

Initial Search for 9-keV XTR from a 28-GeV Beam at SPPS

Description: The potential to use x-ray transition radiation (XTR) as a beam diagnostic and coherent XTR (CXTR) as a gain diagnostic in an x-ray FEL was proposed previously. At that time we noted that the unique configuration of the SLAC Sub-picosecond Photon Source (SPPS) with its known x-ray wiggler source, a special three-element x-ray monochromator, x-ray transport line, and experimental end station with x-ray detectors made it an ideal location for an XTR feasibility experiment. Estimates of the XTR compared to the SPPS source strength were done, and initial experiments were performed in September 2005. Complementary measurements on optical transition radiation (OTR) far-field images from a 7-GeV beam are also discussed.
Date: April 16, 2007
Creator: Lumpkin, A.H.; /Argonne; Hastings, J.B.; /SLAC; Rule, D.W. & Ctr., /Naval Surface Warfare
Partner: UNT Libraries Government Documents Department

Inelastic x-ray scattering at the National Synchrotron Light

Description: The research program at the inelastic x-ray scattering beamline at the National Synchrotron Light Source is focused on the study of elementary excitations in condensed matter with total energy resolution on the order of 0.1 eV to 1.0 eV. Results from selected experiments are reported to demonstrate the capability of the beamline as well as the information can be obtained from inelastic x- ray scattering experiments.
Date: December 31, 1995
Creator: Kao, C.-C.; Caliebe, W.A.; Hastings, J.B.; Hamalainen, K. & Krisch, M.H.
Partner: UNT Libraries Government Documents Department

Nuclear Bragg x-ray scattering of synchrotron radiation by sup 57 Fe sub 2 O sub 3

Description: A program of studies of nuclear Bragg x-ray scattering with {sup 57}Fe{sub 2}O{sub 3} at the National Synchrotron Light Source at Brookhaven National Laboratory and at the Cornell University CHESS facility is reviewed. Two main areas, instrumentation development and studies of dynamical diffraction processes, are described. The latter area has included: measurements of the temporal behaviour of nuclear collective decay mode and direct observation of polarization mixing. 7 refs., 5 figs.
Date: January 1, 1989
Creator: Haustein, P.E.; Berman, L.E.; Faigel, G.; Grover, J.R.; Hastings, J.B. & Siddons, D.P.
Partner: UNT Libraries Government Documents Department

BNL Activities in Advanced Neutron Source Development: Past and Present

Description: Brookhaven National Laboratory has been involved in advanced neutron sources almost from its inception in 1947. These efforts have mainly focused on steady state reactors beginning with the construction of the first research reactor for neutron beams, the Brookhaven Graphite Research Reactor. This was followed by the High Flux Beam Reactor that has served as the design standard for all the subsequent high flux reactors constructed worldwide. In parallel with the reactor developments BNL has focused on the construction and use of high energy proton accelerators. The first machine to operate over 1 GeV in the world was the Cosmotron. The machine that followed this, the AGS, is still operating and is the highest intensity proton machine in the world and has nucleated an international collaboration investigating liquid metal targets for next generation pulsed spallation sources. Early work using the Cosmotron focused on spallation product studies for both light and heavy elements into the several GeV proton energy region. These original studies are still important today. In this report we discuss the facilities and activities at BNL focused on advanced neutron sources. BNL is involved in the proton source for the Spallation Neutron source, spectrometer development at LANSCE, target studies using the AGS and state-of-the-art neutron detector development.
Date: June 14, 1998
Creator: Hastings, J.B.; Ludewig, H.; Montanez, P.; Todosow, M.; Smith, G.C. & Larese, J.Z.
Partner: UNT Libraries Government Documents Department

BNL ACTIVITIES IN ADVANCED NEUTRON SOURCE DEVELOPMENT: PAST AND PRESENT

Description: Brookhaven National Laboratory has been involved in advanced neutron sources almost from its inception in 1947. These efforts have mainly focused on steady state reactors beginning with the construction of the first research reactor for neutron beams, the Brookhaven Graphite Research Reactor. This was followed by the High Flux Beam Reactor that has served as the design standard for all the subsequent high flux reactors constructed worldwide. In parallel with the reactor developments BNL has focused on the construction and use of high energy proton accelerators. The first machine to operate over 1 GeV in the world was the Cosmotron. The machine that followed this, the AGS, is still operating and is the highest intensity proton machine in the world and has nucleated an international collaboration investigating liquid metal targets for next generation pulsed spallation sources. Early work using the Cosmotron focused on spallation product studies for both light and heavy elements into the several GeV proton energy region. These original studies are still important today. In the sections below the authors discuss the facilities and activities at BNL focused on advanced neutron sources. BNL is involved in the proton source for the Spallation Neutron source, spectrometer development at LANSCE, target studies using the AGS and state-of-the-art neutron detector development.
Date: June 14, 1998
Creator: HASTINGS,J.B.; LUDEWIG,H.; MONTANEZ,P.; TODOSOW,M.; SMITH,G.C. & LARESE,J.Z.
Partner: UNT Libraries Government Documents Department

Ultrafast Time-Resolved Electron Diffraction with Megavolt Electron Beams

Description: An rf photocathode electron gun is used as an electron source for ultrafast time-resolved pump-probe electron diffraction. We observed single-shot diffraction patterns from a 160 nm Al foil using the 5.4 MeV electron beam from the Gun Test Facility at the Stanford Linear Accelerator. Excellent agreement with simulations suggests that single-shot diffraction experiments with a time resolution approaching 100 fs are possible.
Date: October 24, 2006
Creator: Hastings, J.B.; /SLAC; Rudakov, F.M.; U., /Brown; Dowell, D.H.; Schmerge, J.F. et al.
Partner: UNT Libraries Government Documents Department

Precision Measurement of the Undulator K Parameter using Spontaneous Radiation

Description: Obtaining precise values of the undulator parameter, K, is critical for producing high-gain FEL radiation. At the LCLS [1], where the FEL wavelength reaches down to 1.5 {angstrom}, the relative precision of K must satisfy ({Delta}K/K){sub rms} {approx}&lt; 0.015% over the full length of the undulator. Transverse misalignments, construction errors, radiation damage, and temperature variations all contribute to errors in the mean K values among the undulator segments. It is therefore important to develop some means to measure relative K values, after installation and alignment. We propose a method using the angle-integrated spontaneous radiation spectrum of two nearby undulator segments, and the natural shot-to-shot energy jitter of the electron beam. Simulation of this scheme is presented using both ideal and measured undulator fields. By ''leap-frogging'' to different pairs of segments with extended separations we hope to confirm or correct the values of K, including proper tapering, over the entire 130-m long LCLS undulator.
Date: April 17, 2007
Creator: Welch, J.J.; Arthur, J.; Emma, P.; Hastings, J.B.; Huang, Z.; Nuhn, H.D. et al.
Partner: UNT Libraries Government Documents Department

Matter in Extreme Conditions Instrument - Conceptual Design Report

Description: The SLAC National Accelerator Laboratory (SLAC), in collaboration with Argonne National Laboratory (ANL), Lawrence Livermore National Laboratory (LLNL), and the University of California at Los Angeles (UCLA), is constructing a Free-Electron Laser (FEL) research facility. The FEL has already met its performance goals in the wavelength range 1.5 nm - 0.15 nm. This facility, the Linac Coherent Light Source (LCLS), utilizes the SLAC 2-Mile Linear Accelerator (linac) and will produce sub-picosecond pulses of short wavelength X-rays with very high peak brightness and almost complete transverse coherence. The final one-third of the SLAC linac is used as the source of electrons for the LCLS. The high energy electrons are transported across the SLAC Research Yard, into a tunnel which houses a long undulator. In passing through the undulator, the electrons are bunched by the force of their own synchrotron radiation and produce an intense, monochromatic, spatially coherent beam of X-rays. By varying the electron energy, the FEL X-ray wavelength is tunable from 1.5 nm to 0.15 nm. The LCLS includes two experimental halls as well as X-ray optics and infrastructure necessary to create a facility that can be developed for research in a variety of disciplines such as atomic physics, materials science, plasma physics and biosciences. This Conceptual Design Report, the authors believe, confirms the feasibility of designing and constructing an X-ray instrument in order to exploit the unique scientific capability of LCLS by creating extreme conditions and study the behavior of plasma under those controlled conditions. This instrument will address the Office of Science, Fusion Energy Sciences, mission objective related to study of Plasma and Warm Dense Matter as described in the report titled LCLS, the First Experiments, prepared by the LCLS Scientific Advisory Committee (SAC) in September 2000. The technical objective of the LCLS Matter in Extreme Conditions (MEC) ...
Date: December 9, 2009
Creator: Boyce, R.F.; Boyce, R.M.; Haller, G.; Hastings, J.B.; Hays, G.; Lee, H.J. et al.
Partner: UNT Libraries Government Documents Department

IN VACUUM UNDULATOR TASK FORCE REPORT

Description: The Green-Chasman lattice, which is the basis for both NSLS storage rings, was conceived with insertion devices in mind. Long, field-free straight sections were provided in the design. The electron optics were chosen so that these sections had zero dispersion and the effects of new magnetic structures placed in these regions would have minimal effect on the emittance of the electron beam. This design concept has been followed by all high-brightness rings which were built subsequent to the NSLS. The X-Ray Ring straight sections also have a very small vertical {beta} function, in addition to the zero dispersion. This was done to optimize the brightness of wiggler sources. There is a further benefit however. The {beta} function determines the beam size and divergence at a particular point in the storage ring lattice. The size is proportional to {radical}{beta} and the divergence is proportional to 1/{radical}{beta}. Thus the electron beam is very small at the center of the X-Ray Ring straight sections. In the initial development of the insertion device program, no specific advantage was taken of this feature. Of the eight straight sections in the X-Ray Ring lattice, five are readily available for magnetic insertion devices and the remaining three are dedicated to radio-frequency drive cavities (2) and injection (1).
Date: June 1, 1998
Creator: HASTINGS,J.B.; KAO,C.C.; STEFAN,P.; BURLEY,S.; CARGILL,G.S.; CHANCE,M. et al.
Partner: UNT Libraries Government Documents Department

Soft x-ray resonant magnetic scattering study of thin films and multilayers

Description: A brief review of using soft x-ray resonant magnetic scattering in the study of magnetic thin films and multilayers is given. Results from recent studies of thin Fe films and Fe/Gd multilayers are used as examples to demonstrate the information can be obtained and the unique features of this technique. Comparison is also made with related techniques: magneto-optical Kerr effect, Faraday effect, and magnetic circular dichroism. 9 refs., 4 figs.
Date: January 1, 1991
Creator: Kao, C.C.; Johnson, E.D.; Hastings, J.B.; Siddons, D.P. (Brookhaven National Lab., Upton, NY (United States)) & Vettier, C. (European Synchrotron Radiation Facility, 38 - Grenoble (France))
Partner: UNT Libraries Government Documents Department

Effects of the hyperfine interactions on the decay of the collective nuclear excited states in. alpha. -hematite

Description: In this paper the time dependence of the coherent decay of nuclear excited state in an {alpha}-{sup 57}Fe{sub 2}O{sub 3} single crystal is presented. The experiment was carried out in diffraction geometry. A highly monocromatized and collimated beam of synchrotron radiation was used for the excitation of nuclear levels. Quantum beat spectra taken below and above the (7,7,7) pure nuclear reflection of hematite show a characteristic pattern corresponding to the magnetic and quadrupole hyperfine interactions. 16 refs., 1 fig.
Date: January 1, 1989
Creator: Faigel, G.; Berman, L.E.; Grover, J.R.; Hastings, J.B.; Haustein, P.E.; Siddons, D.P. (Hungarian Academy of Sciences, Budapest (Hungary). Central Research Inst. for Physics et al.
Partner: UNT Libraries Government Documents Department

A three-crystal spectrometer for 150 KeV synchrotron radiation

Description: A triple axis spectrometer for high energy ({ge}150 keV) synchrotron radiation has been constructed and characterized. The reciprocal space resolution function of this instrument has been measured using perfect silicon crystals as monochromator, sample, and analyzer. It was found to have dimensions of 1.0 {times} 10{sup {minus}5}{angstrom}{sup {minus}1} and 2.3 {times} 10{sup {minus}4}{angstrom}{sup {minus}1} in the directions perpendicular and parallel to the momentum transfer {rvec Q} respectively, comparable to those achievable using standard 8 keV triple axis instruments. The large penetration depths of high energy x-ray photons, combined with the high instrumental resolution, opens new possibilities in the study of truly bulk condensed matter systems. 7 refs., 5 figs.
Date: January 1, 1988
Creator: Hastings, J.B.; Siddons, D.P.; Berman, L.E.; Schneider, J.R. (Brookhaven National Lab., Upton, NY (USA) & Hahn-Meitner-Institut Berlin G.m.b.H. (Germany, F.R.))
Partner: UNT Libraries Government Documents Department