To take full advantage of advanced data collection techniques and high beam flux at next‐generation macromolecular crystallography beamlines, rapid and reliable methods will be needed to mount and ...align many samples per second. One approach is to use an acoustic ejector to eject crystal‐containing droplets onto a solid X‐ray transparent surface, which can then be positioned and rotated for data collection. Proof‐of‐concept experiments were conducted at the National Synchrotron Light Source on thermolysin crystals acoustically ejected onto a polyimide `conveyor belt'. Small wedges of data were collected on each crystal, and a complete dataset was assembled from a well diffracting subset of these crystals. Future developments and implementation will focus on achieving ejection and translation of single droplets at a rate of over one hundred per second.
Over the past several decades the oeuvre of Rembrandt has been the subject of extensive art historical and scientific investigations. One of the most striking features to emerge is his frequent ...re-use of canvases and panels. The painting An Old Man in Military Costume(78.PB.246), in the collection of the J. Paul Getty Museum, is an example of such a re-used panel. Conventional imaging techniques revealed the presence of a second portrait under the surface portrait, but the details of this hidden portrait have not yet been revealed. Vermilion (HgS) has been identified to have been used nearly exclusively in the flesh tones of the lower painting, suggesting that element-specific XRF imaging might successfully image the hidden portrait. To test this hypothesis, a full-scale mock-up of the painting was created, including a "free impression" of the hidden portrait, reproducing as closely as possible the pigments and paint stratigraphy of the original painting. XRF imaging of the mock-up painting was conducted using three different XRF imaging systems: a mobile X-ray tube based system and two synchrotron-based setups (one equipped with multiple SDDs and one equipped with a Maia detector). The sensitivity, limits of detection and imaging capabilities of each system under the chosen experimental conditions are evaluated and compared. The results indicate that an investigation of the original painting by this method would have an excellent chance of success.
The Vertically Integrated Photon Imaging Chip (VIPIC) was custom‐designed for X‐ray photon correlation spectroscopy, an application in which occupancy per pixel is low but high time resolution is ...needed. VIPIC operates in a sparsified streaming mode in which each detected photon is immediately read out as a time‐ and position‐stamped event. This event stream can be fed directly to an autocorrelation engine or accumulated to form a conventional image. The detector only delivers non‐zero data (sparsified readout), greatly reducing the communications overhead typical of conventional frame‐oriented detectors such as charge‐coupled devices or conventional hybrid pixel detectors. This feature allows continuous acquisition of data with timescales from microseconds to hours. In this work VIPIC has been used to measure X‐ray photon correlation spectroscopy data on polystyrene latex nano‐colliodal suspensions in glycerol and on colloidal suspensions of silica spheres in water. Relaxation times of the nano‐colloids have been measured for different temperatures. These results demonstrate that VIPIC can operate continuously in the microsecond time frame, while at the same time probing longer timescales.
Preliminary X‐ray correlation spectroscopy results from the novel three‐dimensional vertically integrated photon imaging chip (VIPIC) detector are presented.
Monolithic arrays of silicon
p-n
junctions are commonly used to deliver spatial information on impinging radiation, with the advantages of low-noise and fast signal generation. Additionally, array ...geometries also allow for a segmentation of a large area into individual channels that can be read out in parallel, so that a high-event rate can be managed. To optimize the noise performance, however, some key points must be addressed to control the silicon/silicon oxide interface. Replacing the
p-n
junctions with silicon drift sensors avoids noise related to the interface states, at the expense of a more complicated process and slower signals. In this paper, some of the aspects needing consideration when engineering a monolithic array of silicon sensors are reviewed.
Arrays of silicon sensors can be used in those spectroscopic applications where a high event throughput is needed, for example, in synchrotron-based experiments. However, in such arrays, several ...noise contributions, beyond the well-known leakage, thermal, and flicker noises, can be present, which are absent in single-channel detectors. Additional noise is generated ultimately by the condition at the silicon/silicon-oxide interface, which in turn depends on the parameters of the silicon oxide over the not-implanted gaps. We discuss how to control this region to obtain the best spectroscopic performances.
X-ray free-electron lasers (XFELs) provide very intense X-ray pulses suitable for macromolecular crystallography. Each X-ray pulse typically lasts for tens of femtoseconds and the interval between ...pulses is many orders of magnitude longer. Here we describe two novel acoustic injection systems that use focused sound waves to eject picoliter to nanoliter crystal-containing droplets out of microplates and into the X-ray pulse from which diffraction data are collected. The on-demand droplet delivery is synchronized to the XFEL pulse scheme, resulting in X-ray pulses intersecting up to 88% of the droplets. We tested several types of samples in a range of crystallization conditions, wherein the overall crystal hit ratio (e.g., fraction of images with observable diffraction patterns) is a function of the microcrystal slurry concentration. We report crystal structures from lysozyme, thermolysin, and stachydrine demethylase (Stc2). Additional samples were screened to demonstrate that these methods can be applied to rare samples.
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•Acoustic methods inject crystal-containing droplets directly from microplate wells•On-demand acoustic injection uses crystals efficiently without orifices or clogging•Diffraction patterns from crystals measuring several tens of μm are of high quality•Complete datasets can be obtained from fewer than 50,000 crystals
Acoustic droplet ejection provides an automated tool for efficient use of protein crystals in SFX experiments. Roessler et al. used this method to deliver crystal-containing droplets into the XFEL beam to coincide with each X-ray pulse.
We developed a new front-end application-specific integrated circuit (ASIC) to upgrade the Maia X-ray microprobe. The ASIC instruments 32 configurable channels that perform either positive or ...negative charge amplification, pulse shaping, peak amplitude, and time extraction along with buffered analog storage. At a gain of 3.6 V/fC, 1-<inline-formula> <tex-math notation="LaTeX">\mu \text{s} </tex-math></inline-formula> peaking time, and a temperature of 248 K, an electronic resolution of 13 and 10 <inline-formula> <tex-math notation="LaTeX">e^{-} </tex-math></inline-formula> rms was measured with and without a silicon drift detector (SDD) sensor, respectively. A spectral resolution of 170-eV full-width at half-maximum (FWHM) at 5.9 keV was obtained with an 55 Fe source. The channel linearity was better than ± 1 % with rate capabilities up to 40 kcps. The ASIC was fabricated in a commercial 250-nm process with a footprint of 6.3 mm <inline-formula> <tex-math notation="LaTeX">\times </tex-math></inline-formula> 3.9 mm and dissipates 167 mW of static power.
In order to meet the challenges of EXAFS and XANES spectroscopy of dilute systems, a custom integrated circuit has been fabricated which integrates 32 complete energy resolving photon counting chains ...onto a 6mm X 4mm chip. This paper reports on initial tests of a 96-element detector implementation using low-leakage diodes fabricated at BNL, and on our plans for a 384-channel version. This large array will initially also use the same diodes but eventually will use a hexagonal drift-detector array. The ASIC is read out through an embedded microcontroller device, and a software package has been written to allow highly automated setup of the entire system and straightforward integration into standard data acquisition packages.
We present a low-power, low-noise prototype pixel readout application specific integrated circuit (ASIC) for hyperspectral enegy-resolving X-ray imaging detectors. The ASIC provides 16-by-16 channels ...to read out positive and negative charges from 16-by-16 heagonal silicon or CZT detector arrays, at a pitch size of 250 \mu \mathrm{m}, to achieve good spatial resolution and the ability to record the energy of a detected photon as well as its position. The readout is done by bumpbonding the anodes to the inputs of the ASIC. Each channel of the ASIC provides low-noise charge amplification, high-order shaping with baseline stabilization, discrimination, extraction of amplitude (with neighbour channels), multiplexing, and dissipates \sim0.6 mW. A smart readout of the triggered pixel and its adjacent six pixels in the hexagonal configuration allows reconstruction of events with charge sharing correction, and can be used to estimate the depth of the photon interaction and to suppress background events. The target equivalent noise charge (ENC) is \sim10 electrons for silicon detector pixel and \sim15 electrons for CZT detector pixel.
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