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R ADIOLOGICAL P ROTECTION S TUDIES FOR NGLS XTOD S HANJIE X IAO , M ARIO S ANTANA -L EITNER AND S AYED R OKNI SLAC N ATIONAL A CCELERATOR L ABORATORY R ICK D ONAHUE , P AUL E MMA , J AMES F LOYD AND T ONY W ARWICK L AWRENCE B ERKELEY N ATIONAL L ABORATORY SLAC-TN-13-003 LBNL-DOC-### December, 2013 P REPARED FOR THE D EPARTMENT OF E NERGY U NDER C ONTRACT N UMBER DE-AC02-76SF00515 & DE-AC02-05CH11231

The optical design of a two-dimensional imaging soft X-ray spectrometer is described. A monochromator will produce a dispersed spectrum in a narrow vertical illuminated stripe (∼2 µm wide by ∼2 mm tall) on a sample. The spectrometer will use inelastically scattered X-rays to image the extended field on the sample in the incident photon energy direction (vertical), resolving the incident photon energy. At the same time it will image and disperse the scattered photons in the orthogonal (horizontal) direction, resolving the scattered photon energy. The principal challenge is to design a system that images from the flat-field illumination of the sample to the flat field of the detector and to achieve sufficiently high spectral resolution. This spectrometer provides a completely parallel resonant inelastic X-ray scattering measurement at high spectral resolution (∼30000) over the energy bandwidth (∼5 eV) of a soft X-ray absorption resonance.

Super high quality aspherical x-ray mirrors with a residual slope error of ∼100 nrad (root-mean-square) and a height error of ∼1-2 nm (peak-to-valley), and even lower, are now available from a number of the most advanced vendors utilizing deterministic polishing techniques. The mirror specification for the fabrication is based on the simulations of the desired performance of the mirror in the beamline optical system and is normally given with the acceptable level of deviation of the mirror figure and finish from the desired ideal shape. For example, in the case of aspherical x-ray mirrors designed for the Advanced Light Source (ALS) QERLIN beamline, the ideal shape is defined with the beamline application (conjugate) parameters and their tolerances. In this paper, we first discuss an original procedure and dedicated software developed at the ALS X-Ray Optics Laboratory (XROL) for optimization of beamline performance of pre-shaped hyperbolic and elliptical mirrors. The optimization is based on results of ex situ surface slope metrology and consists in minimization of the mirror shape error by determining the conjugate parameters of the best-fit ideal shape within the specified tolerances. We describe novel optical metrology instrumentation, measuring techniques, and analytical methods used at the XROL for acquisition of surface slope data and optimization of the optic's beamline performance. The high efficacy of the developed experimental methods and data analysis procedures is demonstrated in results of measurements with and performance optimization of hyperbolic and elliptical cylinder mirrors designed and fabricated for the ALS QERLIN beamline.

High-resolution Resonance Inelastic X-ray Scattering (RIXS) is a technique that allows us to probe the electronic excitations of complex materials with unprecedented precision. However, the RIXS process has a low cross section, compounded by the fact that the optical spectrometers used to analyze the scattered photons can only collect a small solid angle and overall have a small efficiency. Here we present a method to significantly increase the throughput of RIXS systems, by energy multiplexing, so that a complete RIXS map of scattered intensity versus photon energy in and photon energy out can be recorded simultaneously1. This parallel acquisition scheme should provide a gain in throughput of over 100.. A system based on this principle, QERLIN, is under construction at the Advanced Light Source (ALS).

Multilayer coated blazed gratings with high groove density are the most promising candidate for ultra-high resolution soft x-ray spectroscopy. They combine the ability of blazed gratings to concentrate almost all diffraction energy in a desired high diffraction order with high reflectance soft x-ray multilayers. However in order to realize this potential, the grating fabrication process should provide a near perfect groove profile with an extremely smooth surface of the blazed facets. Here we report on successful fabrication and testing of ultra-dense saw-tooth substrates with 5,000 and 10,000 lines/mm.

At the Advanced Light Source (ALS), we are developing broadly applicable, high-accuracy, in-situ, at-wavelength wavefront slope measurement techniques for Kirkpatrick-Baez (KB) mirror nano-focusing. In this paper, we report an initial cross-check of ex-situ and in-situ metrology of a bendable temperature stabilized KB mirror. This cross-check provides a validation of the in-situ shearing interferometry currently under development at the ALS.

We present details of design of elliptically bent Kirkpatrick-Baez mirrors developed and successfully used at the advanced light source for submicron focusing. A distinctive feature of the mirror design is an active temperature stabilization based on a Peltier element attached directly to the mirror body. The design and materials have been carefully optimized to provide high heat conductance between the mirror body and substrate. We describe the experimental procedures used when assembling and precisely shaping the mirrors, with special attention paid to laboratory testing of the mirror-temperature stabilization. For this purpose, the temperature dependence of the surface slope profile of a specially fabricated test mirror placed inside a temperature-controlled container was measured. We demonstrate that with active mirror-temperature stabilization, a change of the surrounding temperature by more than 3 K does not noticeably affect the mirror figure. Without temperature stabilization, the rms slope error is changed by approximately 1.5 μrad (primarily defocus) under the same conditions.

The purpose of this document is to outline the Advanced Light Source (ALS) approach for preventing a radiation accident scenario on the ALS experimental floor due to top-off operation. The document will describe the potential risks, the analysis, and the resulting specifications for the controls.

Two new soft X-ray scanning transmission microscopes located at the Advanced Light Source (ALS) have been designed, built and commissioned. Interferometer control implemented in both microscopes allows the precise measurement of the transverse position of the zone plate relative to the sample. Long-term positional stability and compensation for transverse displacement during translations of the zone plate have been achieved. The interferometer also provides low-distortion orthogonal x, y imaging. Two different control systems have been developed: a digital control system using standard VXI components at beamline 7.0, and a custom feedback system based on PC AT boards at beamline 5.3.2. Both microscopes are diffraction limited with the resolution set by the quality of the zone plates. Periodic features with 30 nm half period can be resolved with a zone plate that has a 40 nm outermost zone width. One microscope is operating at an undulator beamline (7.0), while the other is operating at a novel dedicated bending-magnet beamline (5.3.2), which is designed specifically to illuminate the microscope. The undulator beamline provides count rates of the order of tens of MHz at high-energy resolution with photon energies of up to about 1000 eV. Although the brightness of a bending-magnet source is about four orders of magnitude smaller than that of an undulator source, photon statistics limited operation with intensities in excess of 3 MHz has been achieved at high energy resolution and high spatial resolution. The design and performance of these microscopes are described.

The high brightness of the bend magnets at the Advanced Light Source has been exploited to illuminate a scanning transmission X-ray microscope (STXM). This is the first diffraction-limited scanning X-ray microscope to operate with a useful count rate on a synchrotron bend-magnet source. A simple dedicated beamline has been built covering the range of photon energy from 250 eV to 600 eV. The beamline is always available and needs little adjustment. Use of this facility is much easier than that of installations that share undulator beams. This facility provides radiation for C 1s, N 1s and O 1s near-edge X-ray absorption spectromicroscopy with STXM count rates in excess of 1 MHz and with spectral resolution typically 1:2000, limited to about 1:5000.

At the Advanced Light Source (ALS), we are developing broadly applicable, high-accuracy, in situ, at-wavelength wavefront slope measurement techniques for Kirkpatrick-Baez (KB) mirror nano-focusing. We describe here details of the metrology beamline endstation, the at-wavelength tests, and an original alignment method that have already allowed us to precisely set a bendable KB mirror to achieve a FWHM focused spot size of ~;;120 nm, at 1-nm soft x-ray wavelength.

A grand challenge in soft x-ray spectroscopy is to drive the resolving power of monochromators and spectrometers from the 10(4) achieved routinely today to well above 10(5). This need is driven mainly by the requirements of a new technique that is set to have enormous impact in condensed matter physics, Resonant Inelastic X-ray Scattering (RIXS). Unlike x-ray absorption spectroscopy, RIXS is not limited by an energy resolution dictated by the core-hole lifetime in the excitation process. Using much higher resolving power than used for normal x-ray absorption spectroscopy enables access to the energy scale of soft excitations in matter. These excitations such as magnons and phonons drive the collective phenomena seen in correlated electronic materials such as high temperature superconductors. RIXS opens a new path to study these excitations at a level of detail not formerly possible. However, as the process involves resonant excitation at an energy of around 1 keV, and the energy scale of the excitations one would like to see are at the meV level, to fully utilize the technique requires the development of monochromators and spectrometers with one to two orders of magnitude higher energy resolution than has been conventionally possible. Here we investigate the detailed diffraction characteristics of multilayer blazed gratings. These elements offer potentially revolutionary performance as the dispersive element in ultra-high resolution x-ray spectroscopy. In doing so, we have established a roadmap for the complete optimization of the grating design. Traditionally 1st order gratings are used in the soft x-ray region, but we show that as in the optical domain, one can work in very high spectral orders and thus dramatically improve resolution without significant loss in efficiency.

A new beam line (beam line 11.0) at the Advanced Light Source has been designed to employ an SX700 (Peterson, Opt. Commun. 40 (1982) 402) style variable-included-angle plane-grating-monochromator. The extended range available from a specific grating is exploited to cover energies from the carbon 1 s absorption edge to the oxygen 1 s absorption edge with two different gratings (150 and 1200 lines/mm) with dispersion different by a factor of three. The phase space of a zone plate microscope can then be efficiently filled either at low or high resolution (R=2500 and 7500). At the same time the monochromator is designed to cover the energy range from 75 to 1500 eV using the same two gratings at high resolution for spectroscopy. A deformable mirror pair will re-focus to a monochromatic spot 5×10 μm, matched into the acceptance of a fluorescence spectrometer. The monochromator will operate in vertically collimated light and the free choice of focussing parameter provides a guarantee of high resolution even when the power loading is high. However, we will provide a thermally engineered pre-mirror so that the high resolution requirement at low photon energy can be met without loss of efficiency.

MAESTRO, the Microscopic and Electronic STRucture Observatory, currently under construction at the Advanced Light Source (ALS), will be a world premier facility for the study of electronic and structural properties of in situ grown crystals. The new facility will be comprised of several end-stations, including angle-resolved photoemission spectroscopy, μARPES and nARPES end-stations, and a photoemission electron microscope combined with a lowenergy electron microscope (PEEM/LEEM). Redirection of the x-ray beam between the μARPES and PEEM/LEEM end-stations, which are longitudinally separated by 2.5 meters, uses a system of two bendable mirrors, placed in Kirkpatrick-Baez configuration designed for two foci. Here we present the details of the mirrors’ design and report on the characterization of the mirrors carried out at the ALS X-ray optical laboratory (XROL). Optimal tuning and calibration of the mirrors was performed using a technique recently developed at the OML [Opt. Eng. 48(8), 083601 (2009)]. The technique is based on regression analysis of surface slope data obtained with a long trace profiler (LTP). We provide results of tests of temporal and temperature stabilities of the shape of the mirrors. High reliability of the optical metrology with the mirrors has become possible due to a modification of the tuning procedure described in the present article. The modification allows accounting for the gravity sag effect, as well as the LTP systematic error in measurements with significantly curved x-ray optics.

X-ray fluorescence of condensed ${\mathrm{C}}_{60}$ has been recorded in high resolution using monochromatic synchrotron radiation excitation. Strong intensity modulation of constituent spectral features is observed with varying excitation energy up to 10 eV above threshold. The energy dependence is interpreted as due to resonant inelastic x-ray scattering, leading to symmetry selection rules governing the two-photon process in the fully symmetric molecule.

Realizing the experimental potential of high-brightness, next generation synchrotron and free-electron laser light sources requires the development of reflecting x-ray optics capable of wavefront preservation and high-resolution nano-focusing. At the Advanced Light Source (ALS) beamline 5.3.1, we are developing broadly applicable, high-accuracy, in situ, at-wavelength wavefront measurement techniques to surpass 100-nrad slope measurement accuracy for diffraction-limited Kirkpatrick-Baez (KB) mirrors. The at-wavelength methodology we are developing relies on a series of wavefront-sensing tests with increasing accuracy and sensitivity, including scanning-slit Hartmann tests, grating-based lateral shearing interferometry, and quantitative knife-edge testing. We describe the original experimental techniques and alignment methodology that have enabled us to optimally set a bendable KB mirror to achieve a focused, FWHM spot size of 150 nm, with 1 nm (1.24 keV) photons at 3.7 mrad numerical aperture. The predictions of wavefront measurement are confirmed by the knife-edge testing. The side-profiled elliptically bent mirror used in these one-dimensional focusing experiments was originally designed for a much different glancing angle and conjugate distances. Visible-light long-trace profilometry was used to pre-align the mirror before installation at the beamline. This work demonstrates that high-accuracy, at-wavelength wavefront-slope feedback can be used to optimize the pitch, roll, and mirror-bending forces in situ, using procedures that are deterministic and repeatable.

Nano-focusing and brightness preservation for ever brighter synchrotron radiation and free electron laser beamlines require surface slope tolerances of x-ray optics on the order of 100 nrad. While the accuracy of fabrication and ex situ metrology of x-ray mirrors has improved over time, beamline in situ performance of the optics is often limited by application specific factors such as x-ray beam heat loading, temperature drift, alignment, vibration, etc. In the present work, we discuss the recent results from the Advanced Light Source developing high accuracy, in situ, at-wavelength wavefront measurement techniques to surpass 100-nrad accuracy surface slope measurements with reflecting x-ray optics. The techniques will ultimately allow closed-loop feedback systems to be implemented for x-ray nano-focusing. In addition, we present a dedicated metrology beamline endstation, applicable to a wide range of in situ metrology and test experiments. The design and performance of a bendable Kirkpatrick-Baez (KB) mirror with active temperature stabilization will also be presented. The mirror is currently used to study, refine, and optimize in situ mirror alignment, bending and metrology methods essential for nano-focusing application.

We report on the design and construction of a higher energy Scanning Transmission X‐ray Microscope on a new bend magnet beam line at the Advanced Light Source. Previously we have operated such an instrument on a bend magnet for C, N and O 1s NEXAFS spectroscopy. The new instrument will have similar performance at higher energies up to and including the S 1s edge at 2472eV. A new microscope configuration is planned. A more open geometry will allow a fluorescence detector to count emitted photons from the front surface of the sample. There will be a capability for zone plate scanning in addition to the more conventional sample scanning mode. This will add the capability for imaging a massive sample at high resolution over a limited field of view, so that heavy reaction cells may be used to study processes in‐situ, exploiting the longer photon attenuation length and the longer zone plate working distances available at higher photon energy. The energy range will extend down to include the C1s edge at 300eV, to allow high energy NEXAFS microscopic studies to correlate with the imaging of organics in the same sample region of interest.

There is a need for higher resolution spectrometers as a tool for inelastic x‐ray scattering. Currently, resolving power around R = 10,000 is advertised. Measured RIXS spectra are often limited by this instrumental resolution and higher resolution spectrometers using conventional gratings would be prohibitively large. We are engaged in a development program to build blazed multilayer grating structures for diffracting soft x‐rays in high order. This leads to spectrometers with dispersion much higher than is possible using metal coated‐gratings. The higher dispersion then provides higher resolution and the multilayer gratings are capable of operating away from grazing incidence as required. A spectrometer design is presented with a total length 3.8 m and capable of 105 resolving power.

We report on the current state of surface slope metrology on deformable mirrors for soft x-rays at the Advanced Light Source (ALS). While we are developing techniques for in situ at-wavelength tuning, we are refining methods of ex situ visible-light optical metrology to achieve sub-100-nrad accuracy. This paper reports on laboratory studies, measurements and tuning of a deformable test-KB mirror prior to its use. The test mirror was bent to a much different optical configuration than its original design, achieving a 0.38 micro-radian residual slope error. Modeling shows that in some cases, by including the image conjugate distance as an additional free parameter in the alignment, along with the two force couples, fourth-order tangential shape errors (the so-called bird shape) can be reduced or eliminated.

The design of VUV beamlines for the Advanced Light Source is discussed. Features of the design serve to illustrate the careful attention required in order to preserve the performance of the low emittance “third-generation” storage ring, operating with insertion devices.

The U8 is a beam line under construction at the Advanced Light Source (ALS). The beam line will be described along with calculations of its performance and its current status. An 8 cm period undulator is followed by two spherical collecting mirrors, an entrance slit, spherical gratings having a 15{degree} deviation angle, a moveable exit slit, and refocusing and branching mirrors. Internal water cooling is provided to the metal M1 and M2 mirrors as well as to the gratings. Calculations have been made of both the flux output and the resolution over its photon energy range of 20--300 eV. The design goal was to achieve high intensity, 10{sup 12} photons/sec, at a high resolving power of 10,000. The U8 Participating Research Team (PRT) is planning experiments involving the photoelectron spectroscopy of gaseous atoms and molecules, the spectroscopy of ions and actinide spectroscopy.

Design criteria are described, and test results are presented, for prototype undulator beam position monitors at the Advanced Light Source (ALS). The design is based on monitors presently in use at the National Synchrotron Light Source, Brookhaven National Laboratory, with modifications to account for the widely varying and large K values of the undulators to be installed at the ALS. In particular, we have modified the design to simplify the thermal engineering and we have explored techniques to suppress the response of the monitors to soft photons, below 100 eV, so that the beam position can be determined by measuring the higher energy photons which are better collimated.

We have studied the effects of temperature fluctuations on the Advanced Light Source (ALS). By modeling the storage ring support structure, we find that fluctuations of ± 2 to 3°C in the tunnel will cause photon beam motion of the order of the beam size. Temperature stabilization at this level will allow the residual motion of the photon beams to be reduced by a second level of active feedback, operating on signals from photon beam position monitors. Air temperature in the experimental area and the temperature of cooling water serving the beamlines should be constant to ± 1°C. This will provide a suitable environment for experiments.

The Advanced Light Source is currently being upgraded for top-off operation. This major facility upgrade will provide an improvement in brightness from soft x-ray undulators of about one order of magnitude and keep the ALS competitive with the newest intermediate energy light sources. Major components of the upgrade include making the booster synchrotron capable of full energy operation, radiation safety studies, improvements to interlocks and collimation systems, diagnostics upgrades as well as emittance improvements in the main storage ring. Most hardware necessary as part of the upgrade has been installed and commissioned. The radiation safety studies are making good progress and have passed a first outside peer review succesfully. ©2007 IEEE.

The next generation of synchrotrons and free electron lasers requires x-ray optical systems with extremely high-performance, generally, of diffraction limited quality. Fabrication and use of such optics requires highly accurate metrology. In the present paper, we discuss a way to improve the performance of the Long Trace Profiler (LTP), a slope measuring instrument widely used at synchrotron facilities to characterize x-ray optics at high-spatial-wavelengths from approximately 2 mm to 1 m. One of the major sources of LTP systematic error is the detector. For optimal functionality, the detector has to possess the smallest possible pixel size/spacing, a fast method of shuttering, and minimal nonuniformity of pixel-to-pixel photoresponse. While the first two requirements are determined by choice of detector, the non-uniformity of photoresponse of typical detectors such as CCD cameras is around 2-3%. We describe a flat-field calibration setup specially developed for calibration of CCD camera photo-response and dark current with an accuracy of better than 0.5%. Such accuracy is adequate for use of a camera as a detector for an LTP with performance of ~0.1 microradian (rms). We also present the design details of the calibration system and results of calibration of a DALSA CCD camera used for upgrading our LTP-II instrument at the ALS Optical Metrology Laboratory.

Micro-focusing is widely applied at soft and hard x-ray wavelengths. One typical method, in addition to zone plates, is to split the focusing in the tangential and sagittal directions into two elliptically cylindrical reflecting elements, the so-called Kirkpatrick-Baez (KB) pair. In the simplest case each optic is made by grinding and polishing a flat, and applying unequal bending couples to each end. After briefly reviewing the nature of the bending, we show two new methods for optimal adjustment of these mirror systems using our surface normal slope measuring instrument, the long trace profiler (LTP). First, we adapt a method previously used to adjust mirrors on synchrotron radiation beamlines. We measure the slope of the surface before and after a single small adjustment of each bending couple. This permits an approximation to the functional dependence of slope on the adjustments, and allows, by applying the results of a simple matrix calculation, direct adjustment to a nearly final setting. Typically, the near linearity of the problem determines a very fast convergence of the adjustment procedure. Second, we subdivide the slope data from the LTP into three regions on the mirror, and fit a circle to each sub-region by regression. This method also allows rapid iterative adjustment of both bending couples. We show that this method is a particular case of the first one. As an overall indicator of predicted performance, we ray trace, using profiler data, predicting the exact optical performance to be expected during use of the system.

An ultra‐high resolution beamline is being constructed at the Advanced Light Source (ALS) for the study of low energy excitations in strongly correlated systems with the use of high‐resolution inelastic scattering and angle‐resolved photoemission. This new beamline, given the acronym Merlin (for meV resolution line), will cover the energy range 10–150 eV. The monochromator has fixed entrance and exit slits and a plane mirror that can illuminate a spherical grating at the required angle of incidence (as in the SX‐700 mechanism). The monochromator can be operated in two different modes. In the highest resolution mode, the energy scanning requires translating the monochromator chamber (total travel 1.1 m) as well as rotating the grating and the plane mirror in front of the grating. The resolution in this mode is practically determined by the slits width. In the second mode, the scanning requires rotating the grating and the plane mirror. This mode can be used to scan a few eV without a significant resolution loss. The source for the beamline is a 1.9 m long, 90 mm period quasi periodic EPU. The expected flux at the sample is higher than 1011 photons/s at a resolving power of 5 × 104 in the energy range 16–130 eV. A second set of gratings can be used to obtain higher flux at the expense of resolution.

As the emittance of SR rings approaches the diffraction limit for soft x‐rays, one requires not only excellence in design and performance of the optical elements, but also precision and performance of mechanical components, such as mirror manipulators, monochromator scanners and exit slits. We will present simple but efficient solutions for the mechanical systems of this type, commonly encountered in soft x‐ray beamlines. These solutions have been implemented and their performance evaluated with test results from the spectromicroscopy beamline at the Canadian Light Source.

A new strategic plan is in place to upgrade the ALS so it can continue to address fundamental questions, such as size-dependent and dimensional-confinement phenomena at the nanoscale; correlation and complexity in physical, biological, and environmental systems; and temporal evolution, assembly, dynamics and ultrafast phenomena. Moreover, the growing number of ALS users (now exceeding 2,000 per year) requires increased attention. Accordingly, our plan concentrates on projects that will continue to make it possible for ALS users to address grand scientific and technological challenges with incisive world-class tools and quality user support. Our highest priority is to begin top-off operation, in which electrons are injected into the storage ring at intervals of approximately 1 minute. The combination of top-off and concurrent development of small-gap in-vacuum undulators and superconducting undulators will allow an increase in brightness from eight to more than 100 times, depending on the specific undulators and photon energy range. As part of our core mission in the VUV and soft x-ray regions, we plan to exploit these accelerator developments to extend our capabilities for high spatial and temporal resolution and utilize the remarkable coherence properties of the ALS in a new generation of beamlines. Ranked by priority, several proposed beamlines will follow completion of five new beamlines already under construction or funded. The intellectual excitement of the ALS has been a powerful tool in the recruitment and retention of outstanding staff, but additional sustained efforts are required to increase diversity both in gender and in underrepresented groups. To this end, we intend to expand the ALS Doctoral Fellowship Program by giving special emphasis to underrepresented groups. We also envision a distinguished postdoctoral fellowship program with the same emphasis, to increase and diversify our pool of candidates for beamline scientist positions.

Linearly polarized soft x-rays are converted to elliptical polarization at the Fe L3 line (707 eV) using magnetic circular dichroism (MCD) on transmission through thin Fe films. A linear polarizer measured the transmitted polarization at different incidence angles to vary as expected from a model for in-plane magnetization, and also to exhibit a weak MCD effect at normal incidence interpreted to originate from perpendicular interface anisotropy. An MCD signal from a downstream Fe film was produced by switching the helicity of x-rays transmitted through an upstream circular polarizer. Practical considerations for optimizing the production of circular polarization are discussed, and synchrotron radiation applications using these circular polarizing filters are suggested.

The consistency of different instruments and methods for measuring two-dimensional (2D) power spectral density (PSD) distributions are investigated. The instruments are an interferometric microscope, an atomic force microscope (AFM) and the X-ray Reflectivity and Scattering experimental facility, all available at Lawrence Berkeley National Laboratory. The measurements were performed with a gold-coated mirror with a highly polished stainless steel substrate. It was shown that these three techniques provide essentially consistent results. For the stainless steel mirror, an envelope over all measured PSD distributions can be described with an inverse power-law PSD function. It is also shown that the measurements can be corrected for the specific spatial frequency dependent systematic errors of the instruments. The AFM and the X-ray scattering measurements were used to determine the modulation transfer function of the interferometric microscope. The corresponding correction procedure is discussed in detail. Lower frequency investigation of the 2D PSD distribution was also performed with a long trace profiler and a ZYGO GPI interferometer. These measurements are in some contradiction, suggesting that the reliability of the measurements has to be confirmed with additional investigation. Based on the crosscheck of the performance of all used methods, we discuss the ways for improving the 2D PSD characterization of X-ray optics.

General purpose refocus mirrors using Kirkpatrick-Baez geometry have been designed, built and installed at a new undulator beam-line facility to provide spot sizes smaller than 10 microns for specialized spectroscopy experiments at the Advanced Light Source. All the available flux is focused and the focal length is adjustable. The mirrors are fully computer controlled and can be detuned to create a spot as big as 500 microns.

The spectromicroscopy beamline (SM) at the Canadian Light Source (CLS) will provide 100 – 2000 eV photons in a high brightness, high flux, medium resolution and small spot size beam. The beamline consists of an advanced elliptically polarized undulator (EPU) source and a novel entrance slit‐less plane grating monochromator which feeds two branch lines, one optimized for scanning transmission X‐ray microscopy (STXM), the other for X‐ray photoemission electron microscopy (X‐PEEM). This article outlines the beamline design strategy, and discusses the design optimization relative to the requirements for state‐of‐the‐art STXM and X‐PEEM.

Position monitors are implemented in three undulator beamlines at the ALS. Their performance has been studied carefully on one of these lines and is reviewed. The monitors work as expected and show the ALS to be an exceptionally stable source of synchrotron radiation.

A new facility is described that is being constructed for coherent scattering and microscopy at the Advanced Light Source. The undulator beamline delivers maximum coherent flux to two experiment programs. One is for soft x-ray coherent scattering and correlation studies, the other is for soft x-ray diffractive imaging using ptychographic reconstruction techniques. The energy resolution is sufficient for NEXAFS spectroscopy with full polarization control, from below the carbon edge to 2500eV. New instrumentation is planned for wavelength limited 2D imaging and 3D imaging at spatial resolution better than 10nm and for coherent scattering studies with a variety of sample environments including strong magnetic fields and cryogenic temperatures. High speed CCD detectors will make optimum use of the available flux on dedicated data transmission networks.

The ratio of double to single ionization of He by 85--400 eV photons has been measured using cold target recoil ion momentum spectroscopy. This technique allows the elimination of all possible systematic errors discussed so far in the literature on this subject. We find the ratio in this energy range to be about 25% lower than previously assumed.

The SpectroMicroscopy Facility at the Advanced Light Source is based on a high brightness, high‐resolution beamline, and includes a collection of projects designed to exploit the unique characteristics of the soft x‐ray beam. The beamline itself is comprised of a 5‐m long, 5‐cm‐period undulator, a spherical‐grating monochromator with water‐cooled gratings. Adaptive optics refocus the monochromatic beam to two ‘‘microfocus’’ experimental stations with spot sizes less than 50 μm diameter and a third ‘‘nanofocus’’ station uses a zone‐plate lens to further demagnify the microfocus spot. Experimental stations include an ‘‘ultraESCA’’ spectrometer for small‐area spectroscopy and photoelectron diffraction, a scanning transmission x‐ray microscope, and photoelectron microscopes. Commissioning experiments of microscopic actinide photoemission, surface‐core‐level photoelectron diffraction, and high‐resolution soft x‐ray fluorescence demonstrate dramatic improvements in sensitivity due to the high brightness and sma...

We describe a technique to optimally tune and calibrate bendable X-ray optics for submicron focusing. The focusing is divided between two elliptically cylindrical reflecting elements, a Kirkpatrick-Baez pair. Each optic is shaped by applying unequal bending couples to each end of a flat mirror. The developed technique allows optimal tuning of these systems using surface slope data obtained with a slope-measuring instrument, the long trace profiler. Because of the near linearity of the problem, the minimal set of data necessary for the tuning of each bender consists of only three slope traces measured before and after a single adjustment of each bending couple. The data are analyzed with software realizing a method of regression analysis with experimentally found characteristic functions of the benders. The resulting approximation to the functional dependence of the desired shape provides nearly final settings. Moreover, the characteristic functions of the benders found in the course of tuning can be used for retuning to a new desired shape without removal from the beamline and remeasuring. We perform a ray trace using profiler data for the finally tuned optics, predicting the performance to be expected during use of the optics on the beamline.

A new facility for microdiffraction strain measurements and microfluorescence mapping has been built on beamline 12.3.2 at the advanced light source of the Lawrence Berkeley National Laboratory. This beamline benefits from the hard x-radiation generated by a 6 T superconducting bending magnet (superbend). This provides a hard x-ray spectrum from 5 to 22 keV and a flux within a 1 microm spot of approximately 5x10(9) photons/s (0.1% bandwidth at 8 keV). The radiation is relayed from the superbend source to a focus in the experimental hutch by a toroidal mirror. The focus spot is tailored by two pairs of adjustable slits, which serve as secondary source point. Inside the lead hutch, a pair of Kirkpatrick-Baez (KB) mirrors placed in a vacuum tank refocuses the secondary slit source onto the sample position. A new KB-bending mechanism with active temperature stabilization allows for more reproducible and stable mirror bending and thus mirror focusing. Focus spots around 1 microm are routinely achieved and allow a variety of experiments, which have in common the need of spatial resolution. The effective spatial resolution (approximately 0.2 microm) is limited by a convolution of beam size, scan-stage resolution, and stage stability. A four-bounce monochromator consisting of two channel-cut Si(111) crystals placed between the secondary source and KB-mirrors allows for easy changes between white-beam and monochromatic experiments while maintaining a fixed beam position. High resolution stage scans are performed while recording a fluorescence emission signal or an x-ray diffraction signal coming from either a monochromatic or a white focused beam. The former allows for elemental mapping, whereas the latter is used to produce two-dimensional maps of crystal-phases, -orientation, -texture, and -strain/stress. Typically achieved strain resolution is in the order of 5x10(-5) strain units. Accurate sample positioning in the x-ray focus spot is achieved with a commercial laser-triangulation unit. A Si-drift detector serves as a high-energy-resolution (approximately 150 eV full width at half maximum) fluorescence detector. Fluorescence scans can be collected in continuous scan mode with up to 300 pixels/s scan speed. A charge coupled device area detector is utilized as diffraction detector. Diffraction can be performed in reflecting or transmitting geometry. Diffraction data are processed using XMAS, an in-house written software package for Laue and monochromatic microdiffraction analysis.

Two new scanning x-ray transmission microscopes are being built at beamline 5.3.2 and beamline 7.0 of the Advanced Light Source that have novel aspects in their control and acquisition systems. Both microscopes use multiaxis laser interferometry to improve the precision of pixel location during imaging and energy scans as well as to remove image distortions. Beam line 5.3.2 is a new beam line where the new microscope will be dedicated to studies of polymers in the 250–600 eV energy range. Since this is a bending magnet beam line with lower x-ray brightness than undulator beam lines, special attention is given to the design not only to minimize distortions and vibrations but also to optimize the controls and acquisition to improve data collection efficiency. 5.3.2 microscope control and acquisition is based on a PC computer running WINDOWS 2000. All mechanical stages are moved by stepper motors with rack mounted controllers. A dedicated counter board is used for counting and timing and a multi-input/output...

One of the ALS scanning transmission x‐ray microscopes (STXMs) has been moved to the new ALS molecular environmental science beamline 11.0.2. The STXM is located on the microscopy branchline downstream of an elliptically‐polarizing undulator delivering x‐rays from 80 eV to 1900 eV. The wide energy range allows STXM operations with the current zone plate from 190 eV to about 1900 eV, the highest accessible energy with sufficient flux.

We report on a new research and development program at the Advanced Light Source, Lawrence Berkeley National Lab directed to establish both at-wavelength and conventional optical metrology techniques suitable to characterize the surface profile of super-high-quality x-ray optics with sub-microradian precision.