Readout Process Research Articles

Single-Readout High-Density Memristor Crossbar.

High-density memristor-crossbar architecture is a very promising technology for future computing systems. The simplicity of the gateless-crossbar structure is both its principal advantage and the source of undesired sneak-paths of current. This parasitic current could consume an enormous amount of energy and ruin the readout process. We introduce new adaptive-threshold readout techniques that utilize the locality and hierarchy properties of the computer-memory system to address the sneak-paths problem. The proposed methods require a single memory access per pixel for an array readout. Besides, the memristive crossbar consumes an order of magnitude less power than state-of-the-art readout techniques.

A Resonant Rolling Sphere Viscometer Using Magnetic Actuation and Readout

We present a viscosity measurement principle based on a metallic sphere rolling on a plane on a circular trajectory. The sphere is magnetically positioned and driven using a permanent magnet and four actuation coils placed below the rolling surface. This measurement principle is particularly suited for the characterization of thin fluid films and therefore also for cases where small sample volumes are available.We describe our prototype setup consisting of three parts: the probing body (sphere), the actuation part, and the readout part. For the readout two differential transformer arrangements are used, yielding a total of required five coils: one pair of readout coils for one direction and another pair perpendicular to it for the orthogonal direction. The fifth coil is used as primary coil in the differential transformer readout setup where the aforementioned coil pairs act as secondary coils.In this contribution we describe the sensor setup, outline the actuation and readout process and present first measurements.

Studies of the possibility to use Gas Pixel Detector as a fast trigger tracking device

Gas Pixel Detector (GPD) technology offers new possibilities, which make them very attractive for application in existing and future accelerator experiments and beyond. GPDs combine advantages of silicon and gaseous detectors. They can be produced radiation hard and with low power consumption using relatively cheap technology. Low capacitance of the individual pixel channel allows us to obtain a large signal to noise ratio. Using a time projection method for GPD readout one obtains 3D track image with precise coordinate (31 µm) and angular information (0.40°). This feature would allow us to achieve performance of one GPD layer equal to a few layers of silicon detectors. Implementation of a fast readout and data processing at the front-end level allows one to reconstruct a track segment in less than 1 μs, and to use this information for the first level trigger generation. The relevant algorithms of data acquisition and analysis are described and the results of simulations are presented in this paper.

Photoresponsive Molecular Memory Films Composed of Sequentially Assembled Heterolayers Containing Ruthenium Complexes.

Photoresponsive molecular memory films were fabricated by a layer-by-layer (LbL) assembling of two dinuclear Ru complexes with tetrapodal phosphonate anchors, containing either 2,3,5,6-tetra(2-pyridyl)pyrazine or 1,2,4,5-tetra(2-pyridyl)benzene as a bridging ligand (Ru-NP and Ru-CP, respectively), using zirconium phosphonate to link the layers. Various types of multilayer homo- and heterostructures were constructed. In the multilayer heterofilms such as ITO||(Ru-NP)m |(Ru-CP)n , the difference in redox potentials between Ru-NP and Ru-CP layers was approximately 0.7 V, which induced a potential gradient determined by the sequence of the layers. In the ITO||(Ru-NP)m |(Ru-CP)n multilayer heterofilms, the direct electron transfer (ET) from the outer Ru-CP layers to the ITO were observed to be blocked for m>2, and charge trapping in the outer Ru-CP layers became evident from the appearance of an intervalence charge transfer (IVCT) band at 1140 nm from the formation of the mixed-valent state of Ru-CP units, resulting from the reductive ET mediation of the inner Ru-NP layers. Therefore, the charging/discharging ("1"and "0") states in the outer Ru-CP layers could be addressed and interconverted by applying potential pulses between -0.5 and +0.7 V. The two states could be read out by the direction of the photocurrent (anodic or cathodic). The molecular heterolayer films thus represent a typical example of a photoresponsive memory device; that is, the writing process may be achieved by the applied potential (-0.5 or +0.7 V), while the readout process is achieved by measuring the direction of the photocurrent (anodic or cathodic). Sequence-sensitive multilayer heterofilms, using redox-active complexes as building blocks, thus demonstrate great potential for the design of molecular functional devices.

Photoluminescence Characterization of Interface Quality of Bonded Silicon Wafers

Wafer-to-wafer bonding is implemented in fabrication of backside illuminated (BSI) complimentary metal-oxide-semiconductor image sensor (CIS) devices in volume manufacturing. A wafer with illuminated imager and a wafer with readout and image processing electronics are fabricated separately and assembled using wafer-to-wafer bonding. Since the illuminated imager and a wafer with readout and image processing electronics are facing each other at the bonded interface, the quality of wafer-to-wafer bonding interface can affect the performance of finished devices. Room temperature photoluminescence (RTPL) technique was studied as a non-contact, in-line characterization technique for assessing bonding interface quality. Ordinary and bonded, 200 mm Si wafers, with different surface finishing conditions, were characterized by RTPL under two different excitation wavelengths (650 nm and 827 nm) to investigate the effects of surface finishing conditions. Significant variations in RTPL spectra and intensity, suggesting potential electrical property variations, were observed from bonded wafers. RTPL characterization results on ordinary and bonded wafers are introduced as a potential technique for in-line bonding interface quality monitoring.

Magnetically tuned, robust and efficient filtering system for spatially multimode quantum memory in warm atomic vapors

Warm atomic vapor quantum memories are simple and robust, yet suffer from a number of parasitic processes which produce excess noise. For operating in a single-photon regime precise filtering of the output light is essential. Here, we report a combination of magnetically tuned absorption and Faraday filters, both light–direction insensitive, which stop the driving lasers and attenuate spurious fluorescence and four-wave mixing while transmitting narrowband Stokes and anti-Stokes photons generated in write-in and readout processes. We characterize both filters with respect to adjustable working parameters. We demonstrate a significant increase in the signal-to-noise ratio upon applying the filters seen qualitatively in measurements of correlation between the Raman scattered photons.

The Role of Electrostatic Interactions in Binding of Histone H3K4me2/3 to the Sgf29 Tandem Tudor Domain.

Several reader domain proteins that specifically recognize methyllysine-containing histones contain the negatively-charged aspartate or glutamate residues as part of the aromatic cage. Herein, we report thermodynamic analyses for the recognition of histone H3K4me3 and H3K4me2 by the tandem tudor domain of Sgf29 and its recognition site variants. Small uncharged and large aromatic substitutions on the Asp266 site resulted in a significant decrease in binding affinities for both H3K4me3 and H3K4me2, demonstrating the role of the negative charge of Asp266 in the readout process by Sgf29. This study emphasizes the essential contribution of electrostatic interactions to the overall binding affinity, and reveals that the underlying mechanisms for the recognition of Kme2/3 depend on the composition and arrangement of the aromatic cage.

Wingless mediated apoptosis: How cone cells direct the death of peripheral ommatidia in the developing Drosophila eye

Morphogen gradients play pervasive roles in development, and understanding how they are established and decoded is a major goal of contemporary developmental biology. Here we examine how a Wingless (Wg) morphogen gradient patterns the peripheral specialization of the fly eye. The outermost specialization is the pigment rim; a thick band of pigment cells that circumscribes the eye and optically insulates the sides of the retina. It results from the coalescence of pigment cells that survive the death of the outermost row of developing ommatidia. We investigate here how the Wg target genes expressed in the moribund ommatidia direct the intercellular signaling, the morphogenetic movements, and ultimately the ommatidial death. A salient feature of this process is the secondary expression of the Wg morphogen elicited in the ommatidia by the primary Wg signal. We find that neither the primary nor secondary sources of Wg alone are able to promote ommatidial death, but together they suffice to drive the apoptosis. This represents an unusual gradient read-out process in which a morphogen induces its own expression in its target cells to generate a concentration spike required to push the local cellular responses to the next threshold response.

The data acquisition system for a fixed target experiment at NICA complex at JINR and its connection to the ATLAS TileCal readout electronics

Today's large-scale science projects have always encountered challenges in processing large data flow from the experiments, the ATLAS detector records proton-proton collisions provided by the Large Hadron Collider (LHC) at CERN every 50 ns which results in a total data flow of 10 Pb/s. These data must be reduced to the science data product for further analysis, thus a very fast decisions need to be executed, to modify this large amounts of data at high rates. The capabilities required to support this scale of data movement is development and improvement of high-throughput electronics. The upgraded LHC will provide collisions at rates that will be at least 10 times higher than those of today due to it's luminosity by 2022. This will require a complete redesign of the read-out electronics and Processing Units (PU) in the Tile-calorimeter (TileCal) of the ATLAS experiment. A general purpose, high-throughput PU has been developed for the TileCal at CERN, by using several ARM-processors in cluster configuration. The PU is capable of handling large data throughput and apply advanced operations at high rates. This system has been proposed for the fixed target experiment at NICA complex to handle the first level processes and event building. The aim of this work is to have a look at the architecture of the data acquisition system (DAQ) of the fixed target experiment at the NICA complex at JINR, by compiling the data-flow requirements of all the subcomponents. Furthermore, the VME DAQ modules characteristics to control, triggering and data acquisition will be described in order to define the DAQ with maximum readout efficiency, no dead time and data selection and compression.

Real-Time Discrete SPAD Array Readout Architecture for Time of Flight PET

Single photon avalanche diode (SPAD) arrays have proven themselves as serious candidates for time of flight positron emission tomography (PET). Discrete readout schemes mitigate the low-noise requirements of analog schemes and offer very fine control over threshold levels and timing pickup strategies. A high optical fill factor is paramount to timing performance in such detectors, and consequently space is limited for closely integrated electronics. Nonetheless, a production, daily used PET scanner must minimize bandwidth usage, data volume, data analysis time and power consumption and therefore requires a real-time readout and data processing architecture as close to the detector as possible. We propose a fully digital, embedded real-time readout architecture for SPAD-based detector. The readout circuit is located directly under the SPAD array instead of within or beside it to remove the fill factor versus circuit capabilities tradeoff. The overall real-time engine reduces transmitted data by a factor of 8 in standard operational mode. Combined with small local memory buffers, this significantly reduces overall acquisition dead time. A prototype device featuring individual readout for 6 scintillator channels was fabricated. Timing readout is provided by a first photon discriminator and a 31 ps time to digital discriminator, while energy reading and event packaging is done using standard logic in real-time. The dedicated serial output line supports a sustained rate of 170k counts per second (CPS) in waveform mode, while the standard operational mode supports 2.2 MCPS.

Optimized LEKID Structures With Low Crosstalk for Large Detector Arrays

By using LEKIDs the prospect rises to multi-pixel arrays with an extremely small footprint. Moreover, these arrays have the advantage of frequency-division multiplex readout method (FDM). However, the increase of packing density of LEKIDs leads to an increase of crosstalk between adjacent pixels and complicates the readout process significantly. In this paper, we present a newly developed LEKID structure with reduced crosstalk and present their improved performance in terms of equally spaced resonance frequencies within an array. Thus, the array can be realized with a large number of pixels in a small analog readout bandwidth. We present simulation and measurement results of various linear arrays with 5 pixels, which are constructed with the new LEKID structures. When designing the resonance frequencies importance was attached to an equal spacing between the resonance frequencies at around 6 GHz within our available analog readout bandwidth of 400 MHz. The samples were fabricated in niobium thin film technology on silicon and sapphire substrates and then measured at liquid helium temperatures.

Photoreduction of Sm(3+) in Nanocrystalline BaFCl.

We demonstrate that exposure of nanocrystalline BaFCl:Sm(3+) X-ray storage phosphor to blue laser pulses with peak power densities on the order of 10 GW/cm(2) results in conversion of Sm(3+) to Sm(2+). This photoreduction is found to be strongly power-dependent with an initial fast rate, followed by a slower rate. The photoreduction appears to be orders of magnitude more efficient than that for previously reported systems, and it is estimated that up to 50% of the samarium ions can be photoreduced to the divalent state. The main mechanism is most likely based on multiphoton electron-hole creation, followed by subsequent trapping of the electrons in the conduction band at the Sm(3+) centers. Nanocrystalline BaFCl:Sm(3+) is an efficient photoluminescent X-ray storage phosphor with possible applications as dosimetry probes, and the present study shows for the first time that the power levels of the blue light have to be kept relatively low to avoid the generation of Sm(2+) in the readout process. A system comprising the BaFCl:Sm(3+) nanocrystallites embedded into a glass is also envisioned for 3D memory applications.

Enhanced emission extraction and selective excitation of NV centers with all–dielectric nanoantennas

A novel approach to facilitate excitation and readout processes of isolated negatively charged nitrogen‐vacancy (NV) centers is proposed. The approach is based on the concept of all‐dielectric nanoantennas. It is shown that the all‐dielectric nanoantenna can significantly enhance both the emission rate and emission extraction efficiency of a photoluminescence signal from a single NV center in a diamond nanoparticle on a dielectric substrate. The proposed approach provides high directivity, large Purcell factor, and efficient beam steering, thus allowing an efficient far‐field initialization and readout of several NV centers separated by subwavelength distances. image

Time-reversal-symmetric single-photon wave packets for free-space quantum communication.

Readout and retrieval processes are proposed for efficient, high-fidelity quantum state transfer between a matter qubit, encoded in the level structure of a single atom or ion, and a photonic qubit, encoded in a time-reversal-symmetric single-photon wave packet. They are based on controlling spontaneous photon emission and absorption of a matter qubit on demand in free space by stimulated Raman adiabatic passage. As these processes do not involve mode selection by high-finesse cavities or photon transport through optical fibers, they offer interesting perspectives as basic building blocks for free-space quantum-communication protocols.

Non-local effects in dual-probe-sideband Brillouin optical time domain analysis.

According to recent models, non-local effects in dual-probe-sideband Brillouin Optical Time Domain Analysis (BOTDA) systems should be essentially negligible whenever the probe power is below the Stimulated Brillouin Scattering (SBS) threshold. This paper shows that actually there appear non-local effects in this type of systems before the SBS threshold. To explain these effects it is necessary to take into account a full spectral description of the SBS process. The pump pulse experiences a frequency-dependent spectral deformation that affects the readout process differently in the gain and loss configurations. This paper provides a simple analytical model of this phenomenon, which is validated against compelling experimental data, showing good agreement. The main conclusion of our study is that the measurements in gain configuration are more robust to this non-local effect than the loss configuration. Experimental and theoretical results show that, for a total probe wave power of ~1 mW (500 μW on each sideband), there is an up-shifting of ~1 MHz in the Brillouin Frequency Shift (BFS) retrieved from the Brillouin Loss Spectrum, whereas the BFS extracted from the measured Brillouin Gain Spectrum is up-shifted only ~0.6 MHz. These results are of particular interest for manufacturers of long-range BOTDA systems.

Comparative study of MOSFET response to photon and electron beams in reference conditions

A comparative study of radiation-sensitive field effect transistors (RADFETs) response to photon and electron beams has been carried out in reference conditions. Both types of beams, routinely used in clinical radiotherapy, have been applied to RADFETs manufactured by Tyndall National Institute. All tests were carried out on RADFETs of several gate oxide thicknesses, sizes and technological processes. Experimental results showed very similar behaviour in terms of sensitivity, linearity and short-term post-irradiation fading with dose ranges typical of clinical radiation treatments. Influence of the temperature has been minimized by biasing RADFETs at zero temperature coefficient drain current during readout process. This novel experimental study shows that analysed RADFETs can be suitable to be used for dose verification in radiation therapies where electron beams are used in intra-operative radiotherapy (IORT).

Assessment of Random Error in Phantom Dosimetry with the Use of Error Simulation in Statistical Software.

Objective. To investigate if software simulation is practical for quantifying random error (RE) in phantom dosimetry. Materials and Methods. We applied software error simulation to an existing dosimetry study. The specifications and the measurement values of this study were brought into the software (R version 3.0.2) together with the algorithm of the calculation of the effective dose (E). Four sources of RE were specified: (1) the calibration factor; (2) the background radiation correction; (3) the read-out process of the dosimeters; and (4) the fluctuation of the X-ray generator. Results. The amount of RE introduced by these sources was calculated on the basis of the experimental values and the mathematical rules of error propagation. The software repeated the calculations of E multiple times (n = 10,000) while attributing the applicable RE to the experimental values. A distribution of E emerged as a confidence interval around an expected value. Conclusions. Credible confidence intervals around E in phantom dose studies can be calculated by using software modelling of the experiment. With credible confidence intervals, the statistical significance of differences between protocols can be substantiated or rejected. This modelling software can also be used for a power analysis when planning phantom dose experiments.

Contribution of Amplitude Holographic Grating to Diffraction Efficiency of Mixed Transmission Holograms in Photorefractive Bi12TiO20 Piezocrystal

The results of experimental and theoretical studies of the readout process of the mixed transmission holograms recorded in a photorefractive Bi12TiO20 piezocrystal are presented. It is shown, that in comparison with the case of pure phase holograms, traditionally considered in photorefractive sillenite crystals, additional accounting of the amplitude component of the holographic grating leads to a qualitative and quantitative changes in the diffraction efficiency of holographic gratings recorded in this crystal, which allows to successfully interpreting the experimental results.

Compensated Readout for High-Density MOS-Gated Memristor Crossbar Array

Leakage current is one of the main challenges facing high-density MOS-gated memristor arrays. In this study, we show that leakage current ruins the memory readout process for high-density arrays, and analyze the tradeoff between the array density and its power consumption. We propose a novel readout technique and its underlying circuitry, which is able to compensate for the transistor leakage-current effect in the high-density gated memristor array.

Long term OSLD reader stability in the ACDS level one audit.

The Australian Clinical Dosimetry Service (ACDS) has demonstrated the capacity to perform a basic dosimetry audit on all radiotherapy clinics across Australia. During the ACDS’s three and a half year trial the majority of the audits were performed using optically stimulated luminescence dosimeters (OSLD) mailed to facilities for exposure to a reference dose, and then returned to the ACDS for analysis. This technical note investigates the stability of the readout process under the large workload of the national dosimetry audit. The OSLD readout uncertainty contributes to the uncertainty of several terms of the dose calculation equation and is a major source of uncertainty in the audit. The standard deviation of four OSLD readouts was initially established at 0.6 %. Measurements over 13 audit batches—each batch containing 200−400 OSLDs—showed variability (0.5−0.9 %) in the readout standard deviation. These shifts have not yet necessitated a change to the audit scoring levels. However, a standard deviation in OSLD readouts greater than 0.9 % will change the audit scoring levels. We identified mechanical wear on the OSLD readout adapter as a cause of variability in readout uncertainty, however, we cannot rule out other causes. Additionally we observed large fluctuations in the distribution of element correction factors (ECF) for OSLD batches. We conclude that the variability in the width of the ECF distribution from one batch to another is not caused by variability in readout uncertainty, but rather by variations in the OSLD stock.