The peak brilliance reached by today's Free-Electron Laser and Synchrotron light sources requires photon detectors matching their output intensity and other characteristics in order to fully realize ...the sources' potential. The Pixellated Energy Resolving CMOS Imager, Versatile And Large (Percival) is a dedicated soft X-ray imager (0.25–1 keV) developed for this purpose by a collaboration of DESY, Rutherford Appleton Laboratory/STFC, Elettra Sincrotrone Trieste, Diamond Light Source, and Pohang Accelerator Laboratory. Following several generations of prototypes, the Percival “P2M” 2-Megapixel imager—a 4.5×5 cm monolithic, stitched sensor with an uninterrupted imaging area of 4×4 cm2 (1408×1484 pixels of 27×27 μm—was produced and has demonstrated basic functionality with a first-light image using visible light. It is currently being brought to full operation in a front-illuminated configuration. The readout system being commissioned in parallel has been developed specifically for this imager which will produce—at full 300 Hz frame rate—data at 20 Gbit/s. A first wafer with eight Percival P2M chips has undergone backthinning to enable soft X-ray detection. It has been diced and chips are currently being wirebonded. We summarize here the P2M system, the project status, and show the P2M sensor's first response to visible light.
The soxRS regulon functions in protecting Escherichia coli cells against superoxide and nitric oxide. When SoxR is activated by oxidation of its 2Fe–2S cluster, it increases the synthesis of SoxS, ...which then activates its target gene expression. How the oxidized SoxR returns to and is maintained in its reduced state has been under question. To identity genes that constitute the SoxR‐reducing system, we screened an E.coli mutant library carrying a chromosomal soxSp::lacZ fusion, for constitutive mutants. Mutations mapped to two loci: the rsxABCDGE operon (named for reducer of SoxR) that is highly homologous to the rnfABCDGE operon in Rhodobacter capsulatus involved in transferring electrons to nitrogenase, and the rseC gene in the rpoE–rseABC operon. In‐frame deletion of each open reading frame in the rsxABCDGE operon produced a similar constitutive phenotype. The double mutation of rsx and rseC suggested that rsxABCDGE and rseC gene products act together in the same pathway in reducing SoxR. Electron paramagnetic resonance analysis of SoxR and measurement of re‐reduction kinetics support the proposal that rsx and rseC gene products constitute a reducing system for SoxR.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
AGIPD is a charge integrating, hybrid pixel readout ASIC, which is under development for the European XFEL 1, 2. A dynamic gain switching logic at the output of the preamplifier (preamp) is used to ...provide single photon resolution as well as covering a dynamic range of at least 10 super(4) times 12.4 keV photons 3, 4. Moreover, at each point of the dynamic range the electronics noise should be lower than the Poisson fluctuations, which is especially challenging at the points of gain switching. This paper reports on the progress of the chip design on the way to the first full-scale chip AGIPD1.0, focusing on the optimization of the dynamic range and the implementation of protection circuits at the preamplifier input to avoid pixel destruction due to high intense spots.
The charge integrating readout electronics AGIPD (adaptive gain integrating pixel detector) is a hybrid detector system developed for the European XFEL. It features a threefold dynamic gain switching ...to be able to resolve single photons and to cover a dynamic range of 10 super(4) times 12.4 keV photons. As a result of dynamic gain switching, single photon resolution will be achieved in the high gain stage, while the maximum dynamic range will be reached in the low gain stage. The specification to resolve single photons requires a signal-over-noise ratio of at least 10 for a single incoming photon with an energy of 12.4 keV. When using a silicon sensor, that translates to an equivalent noise charge of less than 343 e super(-). Several AGIPD prototype chips have been designed and characterized, particularly focusing on the noise performance. During the testing phase, the dominant noise sources were identified and the corresponding circuit blocks were improved in the subsequent ASICs. This paper reports on the procedures to identify the dominating noise sources, the optimization process of the circuit blocks and discusses the effect of the optimization on the noise performance.
ADP-ribosyl cyclase (ADPR-cyclase) produces a Ca
2+-mobilizing second messenger cyclic ADP-ribose (cADPR) from β-NAD
+. In this study, we examined the molecular basis of which β-adrenergic receptor ...(βAR) stimulation induces cADPR formation and characterized cardiac ADPR-cyclase. The results revealed that isoproterenol-mediated increase of Ca
2+
i in rat cardiomyocytes was blocked by pretreatment with a cADPR antagonistic derivative 8-Br-cADPR, a PKA inhibitor H89 or high concentration of ryanodine. Moreover, incubation of ventricular lysates with isoproterenol, forskolin or cAMP resulted in activation of ADPR-cyclase that was inhibited by pretreatment with H89. Supporting the observations, the cADPR antagonist and H89 blocked 8-CPT-cAMP, a cell-permeant cAMP analog-induced increase in Ca
2+
i but not cGMP-mediated increase. Characterization of partially purified cardiac ADPR-cyclase showed a molecular mass of approximately 42
kDa and no cross-activity with CD38 antibodies, and the enzyme activity was inhibited by Zn
2+ but not dithiothreitol. Microinjection of the enzyme into rat cardiomyocytes increased the level of Ca
2+
i in a concentration-dependent manner. The enzyme-mediated increase of Ca
2+
i was blocked by the cADPR antagonist. These findings suggest that βAR-mediated regulation of Ca
2+
i in rat cardiomyocytes is primed by activation of cardiac ADPR-cyclase via cAMP/PKA signaling and that cardiac ADPR-cyclase differs from CD38 in biochemical and immunological properties.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
With the continual drive towards bigger, better, and brighter light sources, whole new areas of scientific research are possible that would have been unimaginable or even were believed impossible ...before. For example, imaging of single bioparticles has been demonstrated at Free Electron Lasers (FELs) 1, and synchrotron beamlines can now be used to study real-time changes in samples on a timescale of milliseconds. PUBLICATION ABSTRACT
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
The high speed, high dynamic range camera AGIPD Becker, J.; Bianco, L.; Gottlicher, P. ...
2013 IEEE Nuclear Science Symposium and Medical Imaging Conference (2013 NSS/MIC),
01/2013
Conference Proceeding
The European X-Ray Free Electron Laser (XFEL) will provide ultra short, highly coherent X-ray pulses which will revolutionize scientific experiments in a variety of disciplines spanning physics, ...chemistry, materials science, and biology. One of the differences between the European XFEL and other free electron laser sources is the high pulse frequency of 4.5 MHz. The European XFEL will provide pulse trains, consisting of up to 2700 pulses separated by 220 ns (600 μs in total) followed by an idle time of 99.4 ms, resulting in a supercycle of 10 Hz. Dedicated fast 2D detectors are being developed, one of which is the Adaptive Gain Integrating Pixel Detector (AGIPD). AGIPD is based on the hybrid pixel technology. The design goals of the recently produced, radiation hard Application Specific Integrated Circuit (ASIC) with dynamic gain switching amplifiers are (for each pixel) a dynamic range of more than 10 4 12.4 keV photons in the lowest gain, single photon sensitivity in the highest gain, an analog memory capable of storing 352 images, and operation at 4.5 MHz frame rate. A vetoing scheme allows to maximize the number of useful images that are acquired by providing the possibility to overwrite any previously recorded image during the pulse train. The AGIPD will feature a pixel size of (200 μm) 2 and a silicon sensor with a thickness of 500 μm. The image data is read out and digitized between pulse trains.
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