Image Plate Detector Research Articles

Development of a computed tomography system capable of tracking high-velocity unbounded material through a reconstruction volume

The U.S. Army Research Laboratory (ARL) and Lawrence Livermore National Laboratory have developed a high speed computed tomography system that is capable of tracking unbounded material flux through a reconstruction volume at ballistic rates. It achieves this feat by creating three individual time-registered volume reconstructions throughout the duration of a single dynamic event. Each individual volume reconstruction is computed from five attenuation projections, which are collected using five flash X-ray sources and five digital imaging plate detectors. This work summarizes the numerous complexities in combining the 15 sources and 15 detectors into a single diagnostic, the complexities of analyzing multiple reconstruction volumes from a limited number of views, and complications associated with designing an experiment to fit within the bounding conditions of the diagnostic. It continues to demonstrate an example of how free-flowing material propagates through a reconstruction volume during a bullet/target interaction.

A high sensitivity system for luminescence measurement of materials.

A unique combined and multi-disciplinary wavelength multiplexed spectrometer is described. It is furnished with high-sensitivity imaging plate detectors, the power to which can be gated to provide time-resolved data. The system is capable of collecting spectrally resolved luminescence data following X-ray excitation [radioluminescence (RL) or X-ray excited optical luminescence (XEOL)], electron irradiation [cathodoluminescence (CL)] and visible light from light emitting diodes (LEDs) [photoluminescence (PL)]. Time-resolved PL and CL data can be collected to provide lifetime estimates with half-lives from microsecond timeframes. There are temperature stages for the high and low temperature experiments providing temperature control from 20 to 673K. Combining irradiation, time resolved (TR) and TR-PL allows spectrally-resolved thermoluminescence (TL) and optically stimulated luminescence (OSL). The design of two detectors with matched gratings gives optimum sensitivity for the system. Examples which show the advantages and multi-use of the spectrometer are listed. Potential future experiments involving lifetime analysis as a function of irradiation, dose and temperature plus pump-probe experiments are discussed.

Design and optimization of a cone-beam CT system for extremity imaging

To establish a cone beam computed tomography (ECBCT) system for high-resolution imaging of the extremities. Based on three-dimensional X-Ray CT imaging and high-resolution flat plate detector technique, we constructed a physical model and a geometric model for ECBCT imaging, optimized the geometric calibration and image reconstruction methods, and established the scanner system. In the experiments, the pencil vase phantom, image quality (IQ) phantom and a swine feet were scanned using this imaging system to evaluate its effectiveness and stability. On the reconstructed image of the pencil vase phantom, the edges were well preserved with geometric calibrated parameters and no aliasing artifacts were observed. The reconstructed images of the IQ phantom showed a uniform distribution of the CT number, and the noise power spectra were stable in multiple scanning under the same condition. The reconstructed images of the swine feet had clearly displayed the bones with a good resolution. The ECBCT system can be used for highresolution imaging of the extremities to provide important imaging information to assist in the diagnosis of bone diseases.

High resolution, high signal-to-noise crystal spectrometer for measurements of line shifts in high-density plasmas.

The Orion high-resolution x-ray (OHREX) spectrometer has been a successful tool for measuring the shapes of density-broadened spectral lines produced in short-pulse heated plasmas at the Orion laser facility. We have recently outfitted the instrument with a charge-couple device (CCD) camera, which greatly increased the accuracy with which we can perform line-shift measurements. Because OHREX is located on the outside of the Orion target chamber, no provisions for the shielding of electromagnetic pulses are required. With the CCD, we obtained a higher signal-to-noise ratio than we previously obtained with an image-plate detector. This allowed us to observe structure in the image produced by the diffraction from the two OHREX crystals, which was highly reproducible from shot to shot. This structure will ultimately limit the accuracy of our spectroscopic measurements.

Pre‐Transitional Behavior in Tetragonal to Cubic Phase Transition in HfO2 Revealed by High Temperature Diffraction Experiments

Using the container‐less levitation technique, high‐temperature X‐ray diffraction experiments have been performed on HfO2 powders to confirm the temperature dependences of the lattice constants, thermal expansion character, and phase relations. A two‐dimensional imaging plate detector is used for short‐time observations; diffraction data in a wide area are projected in one dimension for Rietveld analysis, as large‐grain growth occurred at high temperatures. The lattice constants, thermal expansions, and c/a ratios for the tetragonal (space group P42/nmc) and cubic (space group Fm3m) HfO2 phases are measured at high temperature. The transition temperature of HfO2 from the tetragonal phase to the cubic phase is specified to be between 2500 and 2550 °C. The pre‐transitional behavior is clearly observed around 2200 °C. As no clear lattice volume change is observed at the transition point from the tetragonal phase to the cubic phase, a phase boundary between the tetragonal phase and the cubic phase has been proposed which does not exhibit a negative slope. It has been estimated that the stable region of the cubic phase is narrow in the higher‐pressure region.

Accurate data processing for neutron Laue diffractometers

The factors affecting the accuracy of structural refinements from image-plate neutron Laue diffractometers are analysed. From this analysis, an improved data-processing method is developed which optimizes the intensity corrections for exposure scaling, wavelength distribution, absorption and extinction corrections, and the wavelength/spatial/time dependence of the image-plate detector efficiencies. Of equal importance is an analysis of the sources of uncertainty in the final corrected intensities, without which bias of the merged intensities occurs, due to the dominance of measurements with small statistical errors though potentially large systematic errors. A new aspect of the impact of detector crosstalk on the counting statistics of area detectors is reported and shown to be significant for the case of neutron Laue diffraction. These methods have been implemented in software which processes data from the KOALA instrument at ANSTO and the now decommissioned VIVALDI instrument at ILL (Grenoble, France). A comparison with earlier data-analysis methods shows a significant improvement in accuracy of the refined structures.

X-Ray Powder Diffraction: Why Not Use CuKβ Radiation?

CuKβ radiation with a wavelength of λ = 1.3923 ? is recommended for crystal structure determination from X-ray powder diffraction using the Rietfeld method. A highly sensitive image plate detector is able to collect enough intensity to record a brilliant X-ray powder pattern in a reasonable time, compared to CuKα1 radiation used today. Especially atomic displacement coefficients could be determined more precisely with the much greater number of reflections recorded. A double-radius Guinier camera attached to a micro-focus rotating anode tube ensures increased brilliance besides high resolution. A simple construction specification is presented to make smart cylindrically bent Ge(111) or Si(111) X-ray monochromators that deliver focused CuKβ radiation. The highly linear response of image plate detectors allows removing of fluorescence radiation simply as background of the pattern. The proposed equipment is a cost-efficient alternative to a liquid gallium-metal-jet X-ray source with maximum power load and a similar wavelength of λ(GaKα1) = 1.34013 ?.

Technique for insulated and non-insulated metal liner X-pinch radiography on a 1 MA pulsed power machine

Broadband, high resolution X-pinch radiography has been demonstrated as a method to view the instability induced small scale structure that develops in near solid density regions of both insulated and non-insulated cylindrical metallic liners. In experiments carried out on a 1-1.2 MA 100-200 ns rise time pulsed power generator, μm scale features were imaged in initially 16 μm thick Al foil cylindrical liners. Better resolution and contrast were obtained using an X-ray sensitive film than with image plate detectors because of the properties of the X-pinch X-ray source. We also discuss configuration variations that were made to the simple cylindrical liner geometry that appeared to maintain validity of the small-scale structure measurements while improving measurement quality.

Calibration of imaging plate detectors to mono-energetic protons in the range 1-200 MeV.

Responses of Fuji Imaging Plates (IPs) to proton have been measured in the range 1-200 MeV. Mono-energetic protons were produced with the 15 MV ALTO-Tandem accelerator of the Institute of Nuclear Physics (Orsay, France) and, at higher energies, with the 200-MeV isochronous cyclotron of the Institut Curie-Centre de Protonthérapie d'Orsay (Orsay, France). The experimental setups are described and the measured photo-stimulated luminescence responses for MS, SR, and TR IPs are presented and compared to existing data. For the interpretation of the results, a sensitivity model based on the Monte Carlo GEANT4 code has been developed. It enables the calculation of the response functions in a large energy range, from 0.1 to 200 MeV. Finally, we show that our model reproduces accurately the response of more complex detectors, i.e., stack of high-Z filters and IPs, which could be of great interest for diagnostics of Petawatt laser accelerated particles.

X-ray spectrometer having 12 000 resolving power at 8 keV energy.

An x-ray spectrometer employing a thin (50 μm) silicon transmission crystal was used to record high-resolution Cu Kα spectra from a laboratory x-ray source. The diffraction was from the (331) planes that were at an angle of 13.26° to the crystal surface. The components of the spectral lines resulting from single-vacancy (1s) and double-vacancy (1s and 3d) transitions were observed. After accounting for the natural lifetime widths from reference double-crystal spectra and the spatial resolution of the image plate detector, the intrinsic broadening of the transmission crystal was measured to be as small as 0.67 eV and the resolving power 12 000, the highest resolving power achieved by a compact (0.5 m long) spectrometer employing a single transmission crystal operating in the hard x-ray region. By recording spectra with variable source-to-crystal distances and comparing to the calculated widths from various geometrical broadening mechanisms, the primary contributions to the intrinsic crystal broadening were found to be the source height at small distances and the crystal apertured height at large distances. By reducing these two effects, using a smaller source size and vignetting the crystal height, the intrinsic crystal broadening is then limited by the crystal thickness and the rocking curve width and would be 0.4 eV at 8 keV energy (20 000 resolving power).

Modification of a SAXS camera to study structures on multiple scales

A compact small-angle X-ray scattering (SAXS) camera was modified in order to cover a significantly wider size range than that typically covered by conventional lab-based devices. A new housing with a larger sample-to-detector distance (230 → 1300 mm) was developed and a new focusing Gobel mirror was installed to provide a narrower beam width needed to detect scattering intensities very close to the primary beam. A new photon-counting detector was applied to probe the intensity at small scattering vectors while an imaging plate detector serves to simultaneously collect data at large scattering angles up to 90°. The relevant features of the camera are shown and discussed based on raytracing simulations and SAXS measurements, respectively. The minimum scattering vector could be decreased by a factor of 10 to a value of 0.008 nm−1 corresponding to structures up to 780 nm in size. Structural analyses of selected particle systems demonstrate ability of the modified camera to probe various structural parameters on multiple scales, e.g., crystallite size, primary particle size, aggregate size, and fractal dimensions. The modified camera system is promising for structural studies of particle formation and growth/aggregation mechanisms since it provides information on multiple scales ranging from angstroms to several hundred nanometers.

X-ray source development for EXAFS measurements on the National Ignition Facility.

Extended X-ray absorption Fine Structure (EXAFS) measurements require a bright, spectrally smooth, and broad-band x-ray source. In a laser facility, such an x-ray source can be generated by a laser-driven capsule implosion. In order to optimize the x-ray emission, different capsule types and laser irradiations have been tested at the National Ignition Facility (NIF). A crystal spectrometer is used to disperse the x-rays and high efficiency image plate detectors are used to measure the absorption spectra in transmission geometry. EXAFS measurements at the K-edge of iron at ambient conditions have been obtained for the first time on the NIF laser, and the requirements for optimization have been established.

Absolute calibration of imaging plate detectors for electron kinetic energies between 150 keV and 1.75 MeV.

This paper presents the calibration of two different kinds of image plates (IPs) for detecting electrons with kinetic energy in the range of 150 keV-1.75 MeV. The calibration was performed using a 90Sr β source. The paper also provides the measured fading response for the IPs in the time range from 12 min to 18 h. Calibration results are compared to Monte Carlo simulations of energy deposited by the electrons in the sensitive layer of the IPs. It was found that within this energy range a linear relation between simulated energy deposited by the electron in the phosphor layer and the measured photo stimulated luminescence in the IP is adequate to model the response of the IP.

Calibration and characterization of a highly efficient spectrometer in von Hamos geometry for 7-10 keV x-rays.

We have built an absolutely calibrated, highly efficient, Bragg crystal spectrometer in von Hamos geometry. This zinc von Hamos spectrometer uses a crystal made from highly oriented pyrolytic graphite that is cylindrically bent along the non-dispersive axis. It is tuned to measure x-ray spectra in the 7-10 keV range and has been designed to be used on a Ten Inch Manipulator for the Omega and OmegaEP target chambers at the Laboratory for Laser Energetics in Rochester, USA. Significant shielding strategies and fluorescence mitigation have been implemented in addition to an imaging plate detector making it well suited for experiments in high-intensity environments. Here we present the design and absolute calibration as well as mosaicity and integrated reflectivity measurements.

MOMAC: a SAXS/WAXS laboratory instrument dedicated to nanomaterials

This article presents the technical characteristics of a newly built small- and wide-angle X-ray scattering (SAXS/WAXS) apparatus dedicated to structural characterization of a wide range of nanomaterials in the powder or dispersion form. The instrument is based on a high-flux rotating anode generator with a molybdenum target, enabling the assessment of highly absorbing samples containing heavy elements. The SAXS part is composed of a collimation system including a multilayer optic and scatterless slits, a motorized sample holder, a vacuum chamber, and a two-dimensional image-plate detector. All the control command is done through a TANGO interface. Normalization and data correction yield scattering patterns at the absolute scale automatically with a q range from 0.03 to 3.2 Å−1. The WAXS part features a multilayer collimating optic and a two-dimensional image-plate detector with variable sample-to-detector distances. The accessible q range is 0.4–9 Å−1, ensuring a large overlap in q range between the two instruments. A few examples of applications are also presented, namely coupled SAXS/WAXS structure and symmetry determination of gold nanocrystals in solution and characterization of imogolite nanotubes and iron-filled carbon nanotube samples.

Consecutive Phase Transition of Lattice Strain Controlled LiFePO4 for High-Power Li-Ion Batteries

INTRODUCTION Lithium iron phosphate, LiFePO4, becomes conspicuous as a commercially important cathode material due to low cost, high safety, and non-toxic nature. Lithium-ion intercalation proceeds through a two-phase reaction between two compositions close to the endmembers LiFePO4 (LFP-phase) and FePO4 (FP-phase). The first-order phase transformation accompanied with a large volume change of 6.8% hinders moving phase boundaries faster than ever. Co-substituted LiFePO4, represented in Li(Fe1-xZrx)(P1-2xSi2x)O4 or Z2S, which decreases the lattice volume change between two phases, shows six times longer cycle life than undoped LiFePO4 (ref. 1). Here we focus on the Z2S, consisting of moderate two-phase interfaces, and investigate kinetics and mechanisms for the two-phase reaction with reduced lattice mismatch using time-resolved X-ray diffraction. EXPERIMENTAL Undoped LiFePO4 and Li(Fe0.95Zr0.05)(P0.9Si0.1)O4, just called hereafter Z2S, were synthesized in the same manner as reported1. The ex situ X-ray diffraction (XRD) measurements were performed at BL02B2, SPring-8 with a wavelength of 0.699292(4) Å using a Debye-Scherrer camera and an imaging plate detector. The cathode materials for the electrochemical tests were prepared by mixing 80% active material, 10% carbon black, and 10% polyvinylidene fluoride (PVDF) with 1-methyl-2-pyrrolidinone solvent. The composite electrodes were placed in original laminate-type cells in an Ar-filled glovebox with lithium metal as the counter and reference electrodes. LiPF6 (1 M) in a 3:7 volume ratio of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) was used as the electrolyte. The in situ XRD measurements were performed at BL28XU, SPring-8 with a wavelength of 0.619862(2) Å using a 1D detector, MYTHEN 1K. The data were collected in the 2θ range of 10° to 13° with an exposure time of 1 s every 60 s(1C) and 15 s(10C). RESULTS AND DISCCUSION Both Undoped LiFePO4 and Z2S are the same particle size as about 150 nm, indicating independent of nano-sized effects2 and allowing the comparison of the difference of the lattice volume change. Galvanostatic charge/discharge tests were performed. At a low rate of 1C, both of them show the same capacity as 120 mAh/g and the similar shape of charge/discharge curves. At a high rate of 10C, the capacity of Z2S keeps still 90 mAh/g although that of undoped LiFePO4 falls to 75 mAh/g. The difference of both capacities are lager with increasing rates, which indicates the enhancement of the rate capability in Z2S. In order to get information on the static state, the ex-situ XRD and the open-circuit voltage (OCV) measurements were performed. The ex situ XRD patterns show a typical two-phase characteristics in both cathodes as emerged FP-phase peaks from 0.1Li during a charge process. The OCV curves show the flat voltage plateau in a wide range, which also indicates the coexistence of two phases in the reaction. From these results based on an equilibrium system, there is no significant difference in phase transition behavior between undoped LiFePO4 and Z2S. To try to understand what is going on in lithium intercalation reaction indeed and to achieve high power lithium-ion batteries, time-resolved in-situ XRD measurements were performed. At a low rate of 1C, undoped LiFePO4 proceeds via two phase reaction similarly in the results of the ex situ experiments. In Z2S, the peaks belonging to each LFP-phase and FP-phase simply increase or decrease although accompanying with peak broadening. At a high rate of 10C, on the other hand, the peak shift mainly occurs in Z2S compared with undoped LiFePO4. This suggests the quasi-single phase reaction proceeds in Z2S and explains the enhancement of rate capability in Z2S, which is the small lattice volume change. REFERENCES 1. M. Nishijima, T. Ootani, Y. Kamimura, T. Sueki, S. Esaki, S. Murai, K. Fujita, K. Tanaka, K. Ohira, Y. Koyama and I. Tanaka, Nat. Commun., 5 (2014). 2. N. Meethong, H. Y. S. Huang, W. C. Carter and Y. M. Chiang, Electrochemical and Solid State Letters, 10, A134 (2007).

A convergent neutron lens based on glass capillaries

The properties of a convergent neutron lens in the form of an assembly of bent glass capillaries have been experimentally investigated. Each capillary is a conical tube with a length of 22.5 cm, an entrance diameter of 0.25 mm, and an exit diameter of 0.17 mm. The spectrum of thermal neutrons incident on the lens entry is formed on the beam of the IR-8 reactor by means of a diamond microcrystalline filter and investigated with a time-of-flight spectrometer. The spatial distribution of the neutron beam at the exit from the lens is measured using the position-sensitive image plate detector. The measured focal length of the lens is 75–80 mm. The possibility of focusing neutrons with an increase in the local beam density at the lens axis by a factor of 4.9 is demonstrated.

The displacement disorder of atoms in diamond crystals revealed by X-ray imaging plate detector

Cylindrical Imaging Plate Area Detector of Rigaku (IPD) was used to register the X-ray diffraction patterns from diamond crystals grown by Chemical Vapor Deposition (CVD) process. The analysis revealed a deviation from cubic diamond lattice symmetry. X-ray diffraction patterns have been taken by oscillation and stationary crystal methods. Due to high resolution, sensitivity and speed, the IPD detector, allows registration of scattering in the vicinity of Bragg reflections such as broadening, splitting, and satellite reflections. These details were recognized via comparison with the diffraction pattern from a nearly perfect natural diamond crystal and a single crystal of silicon, which were used as diffraction standards. We report data on highly oriented diamond film (HOD) on (001) Si. Powder diffraction patterns show a split of the 111 diffraction line. The line at 2.056Å corresponds to cubic diamond, and the other line at 2.036Å is assigned to a disordered polytype. Two superstructure spots were located at 4.076Å and 4.092Å. Creation of this polytype during growth annihilates desired heteroepitaxy. The issues of lattice disorder, specifically for diamond crystals, are discussed in the framework of kinematical theory of X-ray diffraction.

Improved Rate Capability By Dynamic Crystal Structure Change of Co-Substituted LiFePO4 with Reduced Lattice Mismatch

For the practical use of Lithium-ion battery in electric vehicles, the rate capability should be more improved. Although LiFePO4 is wildly known as the high power cathode materials, the large mismatch between LiFePO4 and FePO4 might still disturb the further improvement of the rate capability. Because the huge volume change during the phase transition require the large activation energy, the suppression of the crystal structure change is one of attracted design principle for cathode materials. Recently, Nishijima et al have reported that Zr-substitution in LiFePO4 eliminates the volume change between LiFePO4 and FePO4 and the cyclability of the doped LiFePO4 is drastically improved[1]. In this study, we investigate the rate capability of the Zr-dopoed LiFePO4. Moreover the phase transition behavior is examined by using operando X-ray diffraction measurements. LiFePO4, called hereafter undoped LFP, and Li(Fe0.95Zr0.05)(P0.9Si0.1)O4, called Zr-doped LFP, were synthesized by the solid solution method in the same manner as reported[1]. The crystal structure of the prepared samples were analyzed by X-ray diffraction (XRD) which were performed at beamline BL02B2, SPring-8 with a wavelength of 0. 699292(4) Å using a Debye-Scherrer camera and an imaging plate detector. The electrodes for the electrochemical tests were prepared by mixing 80% active material, 10% carbon black, and 10% polyvinylidene fluoride (PVDF) with 1-methyl-2-pyrrolidinone solvent. The slurry was then casted onto an Al foil current collector. 1 M LiPF6 in a 3:7 volume ratio of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) was used as the electrolyte. Li foil was used as a counter electrode. operando time-resolved XRD measurements were performed at SPring-8 with a wavelength of 0.619862(2) Å using a 1D detector, Mythen. All the peaks of XRD pattern of the both prepared powder samples are indexed to orthorhombic Pnma space group and any impurity is not observed. The calculated lattice volume of Zr-doped LFP is almost similar to that of undoped LFP. SEM measurements indicate that the particle size of both undoped LFP and Zr-doped LFP is approximately 100 nm. The rate capability of Zr-doped LFP is improved compared with undoped LFP. At 10 C rate, 110 mAh/g is still acquired in Zr-doped LFP, while the capacity of undoped LFP is decreased to 90 mAh/g. The polarization of the discharge profile is also suppressed by Zr substitution. Operando time-resolved XRD measurements reveal that the expansion of solid solution reaction of LiFePO4 and FePO4end-members in nonequilibrium condition. REFERENCES [1] Nishijima, M.; Ootani, T.; Kamimura, Y.; Sueki, T.; Esaki, S.; Murai, S.; Fujita, K.; Tanaka, K.; Ohira, K.; Koyama, Y.; Tanaka, I., Nat. Commun. 5, 4553 (2014).

High energy X-ray pinhole imaging at the Z facility.

A new high photon energy (hν > 15 keV) time-integrated pinhole camera (TIPC) has been developed as a diagnostic instrument at the Z facility. This camera employs five pinholes in a linear array for recording five images at once onto an image plate detector. Each pinhole may be independently filtered to yield five different spectral responses. The pinhole array is fabricated from a 1-cm thick tungsten block and is available with either straight pinholes or conical pinholes. Each pinhole within the array block is 250 μm in diameter. The five pinholes are splayed with respect to each other such that they point to the same location in space, and hence present the same view of the radiation source at the Z facility. The fielding distance from the radiation source is 66 cm and the nominal image magnification is 0.374. Initial experimental results from TIPC are shown to illustrate the performance of the camera.