Two-dimensional Detector System Research Articles

Research and application of differential optical absorption two-dimensional detection system for rotorcraft unmanned aerial vehicle

In order to meet the technical requirements for miniaturization, multi-angle, multi-altitude, and fast simultaneous acquisition of atmospheric pollutants, this study develops an integrated, lightweight, and cost-effective airborne differential optical absorption spectroscopy (DOAS) system. This system is designed in order to be used on a rotorcraft unmanned aerial vehicle (UAV) platform for monitoring atmospheric pollutants. The compositions of the hexacopter UAV platform and the airborne DOAS system are detailed in this work. The system includes a multi axis differential optical absorption spectroscopy (MAX-DOAS) spectral acquisition system, a control system, and a flight environment monitoring system. Commands are sent from a computer via serial communication to drive a gimbal, controlling the azimuth angle and elevation angle of the telescope, with a camera recording the light obstruction. The sunlight scattered by the atmosphere is collected by the telescope and transmitted via fiber optics to the spectrometer, which then transmits the data to the control computer. Additionally, the system captures data of altitude, temperature, humidity, and GPS location during flight, and filters out spectral data obtained under abnormal flight conditions. Stability studies indicate that the mean angular deviations for yaw, roll, and pitch are 0.07°, –0.13°, and –0.12° respectively, which meet the requirements for monitoring stability. Comparative experiments with a commercial ground-based DOAS system show that the correlation coefficients between the monitoring data of both systems are both greater than 0.92, confirming the reliability of the airborne system. In field flight experiments, the airborne DOAS system conducts observations at altitudes of 30 m, 60 m, and 90 m, with the elevation angle set at 0° and the azimuth angle measured every 30° from 0° to 360°. The system successfully obtains the concentration distributions of NO<sub>2</sub>, SO<sub>2</sub>, and HCHO at different azimuth angles and altitudes. The results indicate that the concentrations of these three gases decrease with altitude increasing, with higher concentrations observed in the southeast direction, indicating the presence of pollution sources in that direction. Further analysis with considering altitude changes indicates that the rate of decrease in NO<sub>2</sub> concentration and SO<sub>2</sub> concentration slow down with altitude increasing, while the rate of decrease in HCHO remains relatively constant. These findings indicate that this system effectively meets the technical requirements for simultaneous, rapid, multi-angle, and multi-altitude detection of atmospheric pollutants, providing essential support for the detailed monitoring of complex urban micro-environments.

A method to reduce open optical path noise interference in two-dimensional gas detection of farmland

The two-dimensional distribution method based on the laser spectrum is widely used in the reconstruction of two-dimensional temperature fields or concentration fields. However, the existing methods are all based on small-scale measurements. In large-scale spatial detection of farmland, the detection accuracy cannot reach the expected result due to the long optical path and the noise of various frequencies brought by environmental factors such as vibration, temperature, and other interfering gases. Aiming at the above-mentioned problems, this paper proposes a method to reduce open optical path noise interference in two-dimensional gas detection of farmland to improve detection accuracy. The signal denoising approach combines variational modal decomposition with the SG filtering algorithm to decompose, smooth out, and rebuild the detection signal. In addition, we built a two-dimensional detection system based on an open optical path. Throughout experimental validation, the proposed method outperformed the traditional method by 24% and 19%, respectively, in terms of the fitting degree and fitting effect of the gas absorption curve.

Collagen Structure Orientation at the Bone–Cartilage Interface

Abstract The articular cartilage overlying subchondral bone consists of variously oriented collagen fibres, the detailed organisation of which is essential for cartilage integrity that has suffered damage in degenerative joint disease such as osteoarthritis (OA). A technique attracting particular interest is that of coherent small-angle X-ray scattering mapping; the present investigations are supported by PILATUS, a highly pixelated two-dimensional detector system developed at the Paul Scherrer Institute (PSI). The system has yielded information on the anatomical features that correspond to the large-scale organisation of collagen and the mineralised phase contained within the collagen fibres in the deep cartilage zone. Results obtained from a decalcified cartilage–bone sample have been plotted in terms of the orientation of cartilage and bone components for particular intervals of k-space, showing the organisation of collagen-II within superficial layers and collagen-X in the chondrocyte-rich deeper layers of cartilage. It is apparent in undamaged cartilage that there is a gradual reorientation of the collagen-II fibres of the cartilage, from parallel to the surface of the joint, to normal to the cartilage–bone interface. A similar pattern of orientation is seen below the cement line (the surface at which cartilage anchors to the bone), for the collagen type-I prevalent in bone. Changing the interval of k-space allows subchondral features such as the microvasculature to be seen.

Strain profiles in ion implanted ceramic polycrystals: An approach based on reciprocal-space crystal selection

The determination of the state of strain in implanted materials is a key issue in the study of their mechanical stability. Whereas this question is nowadays relatively easily solved in the case of single crystals, it remains a challenging task in the case of polycrystalline materials. In this paper, we take benefit of the intense and parallel beams provided by third generation synchrotron sources combined with a two-dimensional detection system to analyze individual grains in polycrystals, hence obtaining “single crystal-like” data. The feasibility of the approach is demonstrated with implanted UO2 polycrystals where the in-depth strain profile is extracted for individual grains using numerical simulations of the diffracted signal. The influence of the implantation dose is precisely analyzed for several diffracting planes and grains. This work suggests that, at low fluences, the development of strain is mainly due to ballistic effects with little effect from He ions, independently from the crystallographic orientation. At higher fluences, the evolution of the strain profiles suggests a partial and anisotropic plastic relaxation. With the present approach, robust and reliable structural information can be obtained, even from complex polycrystalline ceramic materials.

Dynamics of slow electrons transmitting through straight glass capillary and tapered glass capillary

It has been found that the transmission rate of the electrons through insulating capillaries as a function of time/incident charge is not the same as that of the ions. The question arises that by using the electrons, if the negative charge patches can be formed to facilitate the transmission of the following electrons, thereby substantiating that the so-called guiding effect works also for electrons. This study aims to observe the time evolutions of the transmission of electrons through a straight glass tube and a tapered glass capillary. This will reveal the details of how and (or) if the negative charge patches can be formed when the electrons transport through them. In this work, a set of MCP/phosphor two-dimensional detection system based on Labview platform is developed to obtain the time evolution of the angular distribution of the transmitted electrons. The pulsed electron beams are obtained to test our detection system. The time evolution of the angular profile of 1.5 keV electrons transmitting through the glass tube/capillary is observed. The transmitted electrons are observed on the detector for a very short time and disappear for a time and then appear again for both the glass tube and tapered glass capillary, leading to an oscillation. The positive charge patches are formed in the insulating glass tube and tapered glass capillary since the secondary electron emission coefficient for the incident energy is larger than 1. It is due to the fact that fast discharge of the deposited charge leads to the increase of the transmission rate, while the fast blocking of the incident electrons due to the deposited positive charge leads to the decrease of the transmission rate. The geometrical configuration of the taper glass capillary tends to make the secondary electrons deposited at the exit part to form the negative patches that facilitate the transmission of electrons. This suggests that if the stable transmission needs to be reached for producing the electron micro-beam by using tapered glass capillaries, the steps must be taken to have the proper grounding and shielding of the glass capillaries and tubes. Our results show a difference in transmission through the insulating capillary between electrons and highly charged ions.

On-Line Determination of Texture in Deep Drawing Steel Sheet by Two-Dimensional X-Ray Diffraction

This paper described the application of a diffraction system based on X-ray area detector on pole figure measurement as well as corresponding computation of orientation distribution functions and the principle of rapid measurement texture. The impact of calculates the orientation distribution function on the conditions of the two-dimensional X-ray diffraction was analyzed; this was illustrated by an example of deep drawing steel sheets texture measurement. ̙̈́˰͇̱̓˰̶̴̿̾ͅ˰̸̱̈́̈́˰̷̱̹͂̿̈́̈́̾˰̸̵̈́˰͇̈́̿˽̴̵̹̹̱̼̽̾̓̿̾˰̴̵̵̳̈́̈́̿͂˰̈́̿˰̸̵̈́˰̵̱̹̱̀̀͂̿̀͂̈́˰̂θ position then fix it, reduce the sample rotation; the texture determination time can be significantly reduced. Reduce the Measuring range of angle χ˰̴̱̾ φ˰̴̵̿̓˰̾̿̈́˰̶̶̵̱̳̈́˰̸̵̈́ calculation of orientation distribution function, it also can significantly reduce the measurement of diffraction data. Several technical problems appeared on the on-line determination of texture based on an X-ray two-dimensional detector system and the possibility to improve the measurement speed and accuracy in the industrial production applications were then discussed.

Characterizing the detection system nonlinearity, internal inelastic background, and transmission function of an electron spectrometer for use in x-ray photoelectron spectroscopy

We present a method for removing spectrometer specific contributions to x-ray photoelectron spectroscopy data. We consider the degree of linearity of the detection system, the strength of the internal analyzer inelastic background, and finally determine the spectrometer's transmission function. The procedures presented here are performed on a SPECS Phoibos 150 hemispherical analyzer with a two-dimensional detection system, but are applicable to a wide variety of different electron spectrometers. The spectrometer's detection system is found to deviate from linear behavior by a few percent over the whole intensity range studied. The size of the analyzer internal inelastic scattering has been measured, and we find that it can normally be neglected at large pass energies or high kinetic energies for most types of analysis (contributing less than 1% at 100 eV pass energy). Finally, we measure the transmission function of the analyzer and lens system for a variety of different settings with the preceding corrections applied, and find that the form of the transmission function is dependent on small changes in the system's settings.

A Geiger-mode avalanche photodiode array for X-ray photon correlation spectroscopy

X-ray photon correlation spectroscopy (XPCS) provides an opportunity to study the dynamics of systems by measuring the temporal fluctuations in a far-field diffraction pattern. A two-dimensional detector system has been developed to investigate fluctuations in the frequency range of several Hz to kHz. The X-ray detector system consists of a thin 100 microm scintillation crystal coupled to a Geiger-mode avalanche photodiode array. In this article the elements of the system are detailed and the detector for XPCS measurements is demonstrated.

Absence of a Detectable Intermediate in the Compound I Formation of Horseradish Peroxidase at Ambient Temperature*

A microsecond-resolved absorption spectrometer was developed to investigate the elementary steps in hydrogen peroxide (H(2)O(2)) activation reaction of horseradish peroxidase (HRP) at ambient temperature. The kinetic absorption spectra of HRP upon the mixing with various concentrations of H(2)O(2) (0.5-3 mm) were monitored in the time range from 50 to 300 mus. The time-resolved spectra in the Soret region possessed isosbestic points that were close to those between the resting state and compound I. The kinetic changes in the Soret absorbance could be well fitted by a single exponential function. Accordingly, no distinct spectrum of the putative intermediate between the resting state and compound I was identified. These results were consistent with the proposal that the O-O bond activation in heme peroxidases is promoted by the imidazolium form of the distal histidine that exists only transiently. It was estimated that the rate constant for the breakage of the O-O bond in H(2)O(2) by HRP is significantly faster than 1 x 10(4) s(-1).

GISAXS View of Vanadium/Cerium Oxide Thin Films and Influence of Lithium Intercalation

An examination of structural modifications, induced by mixing vanadium and cerium oxides and by the introduction of lithium in vanadium and mixed vanadium/cerium oxide films, was performed using synchrotron sourced grazing incidence small-angle X-ray scattering. Samples were sol-gel-derived films, deposited by a dip-coating technique. An analysis of the scattering data, acquired by a two-dimensional detection system, is based on the comparison of the surface and bulk characteristics of the film. The trend of estimated structural modifications is supported by the results of previous investigations on a different length scale, performed by atomic force microscopy.

Development of readout systems for neutron detectors

In recent years, the requirement for a two-dimensional detector system with a relatively good positional resolution has become more crucial for neutron-scattering instruments. Several versatile readout systems have been developed at KENS. Some systems are for He-3 gas detectors, and others are for neutron-scintillators with photo-multiplier tubes (PMT). This report mentions several readout systems for the neutron-scintillators.

Development of a high-performance microstrip gas chamber with a capability of track discrimination for neutron detection

A microstrip gas chamber (MSGC) with a capability of track discrimination for neutron detection was developed whilst ensuring the stability of the MSGC and fulfilling the specifications required for detectors used in high-flux reactors and high-intensity pulsed-neutron sources. The developed two-dimensional detector system comprises an MSGC with individual signal channel read-outs and a new instrument system with a capability of secondary-particle discrimination (InSPaD). The InSPaD identifies the particles—proton and triton—created in the nuclear reaction 3He+n→p+T by a simple, fast and cost-effective method using the difference in the track length, and it allows using a small amount of heavy gas such as C 2H 6 with helium-3 as the filling gas for achieving a high spatial resolution. We describe the concept and design of the developed detector system and show some basic experimental results supporting the feasibility of the detector system with the InSPaD, including the gas gain of the MSGC, spatial uniformity of the gas gain, and pulse-height distribution along the tracks of the secondary particles created in neutron events.

Performance measurement of a new high-resolution detector system for I-131 thyroid studies

A two-dimensional detector system for high-resolution thyroid I-131 scintigraphy was developed. It has a sensitive area of 4/spl times/4 cm/sup 2/ and consists of a lead collimator and an array of 10/spl times/10 BGO crystals combined with a position-sensitive photomultiplier. The spatial resolution and the sensitivity of the detector have been measured and compared to two commercially available gamma cameras. The full-width half-maximum for the new system is 3.8 mm. Furthermore, first patient measurements have been carried out.

Correction of specimen absorption in X-ray diffuse scattering experiments with area-detector systems

Methods for correcting specimen absorption in X-ray diffraction experiments, dedicated to two-dimensional area-detector systems and broad diffuse scattering phenomena, are implemented and tested. The respective transmission factors, in relation to the crystal or specimen shape, are applied to the intensity of every pixel of the two-dimensional detector. The pixel-wise approach allows for a fully quantitative treatment of continuous diffraction information, such as disorder diffuse scattering or scattering from amorphous materials, which is collected with a two-dimensional detector system. This is in contrast to routine data reduction, where the transmission factors are applied to the integrated Bragg intensities only. Furthermore, it is possible to assign different linear attenuation coefficients to the paths of the incident and scattered beams, as is desirable, for instance, in the case of X-ray holography with an internal resonant scatterer. Broad diffuse scattering data collected with synchrotron radiation and numerical calculations are used to study in detail the influence of experimental parameters on the accuracy of the pixel-wise absorption correction.

A Stacked CMOS Active Pixel Image Sensor for Charge Particle Detection and the Application to SIMS

A stacked CMOS active pixel image-sensor (APS) has been developed for detecting various kinds of charged particles and its noise performance has been measured and analyzed. The sensitivity for ions and electrons with keV energy level utilizes for ion microscopy such-as SIMS and electron microscopy, respectively.Charge particles such as ions and electrons with kinetic energy of keV order are useful probes for surface analysis of material. A measurement system which yields two-dimensional image of charge particles is highly demanded. The conventional two-dimensional detection system is composed of a micro channel plate, a florescent plate which receives multiplied secondary electrons and generates a visible image, and a visible image sensor. However, its limited dynamic range and non-linearity in the ion-electron-to-photon conversion process make a quantitative measurement difficult. The proposed system using a stacked CMOS APS has several advantages over the conventional system such as high spatial resolution, no insensitive time, high S/N, wide dynamic range, nondestructive readout capability, high robustness, and low power consumption.

The “RAPID” high rate large area X-ray detector system

The multiwire proportional counter (MWPC) is a well-established device for capturing X-ray images from synchrotron sources and is particularly well suited to dynamic experiments. Its advantages include, almost zero noise, high dynamic range limited only by the electronic memory depth, large area and time resolutions of microseconds. It does however have some limitations, notably in global and local count rate performance. The RAPID two-dimensional detector system delivers a more than twentyfold increase in throughput over present systems. It comprises a “wire MicroGap” detector, which has much higher count rate performance than coventional MWPCs and a sophisticated multi-channel data acquisition system. The system has a global count rate capability of greater than 2 × 10 7 photons s −1 with a maximum local count rate of ∼10 6 photons mm −2s −1. A spatial resolution of ∼200 μm, over an active area of 12.8 × 12.8 cm, has been achieved which compares well with exiting read-out systems. Each electrode of the detector is instrumented with a preamplifier and ADC and the position of the event is determined independently in X and Y by centroiding the induced charge distribution. The X and Y coordinates are correlated using a unique time stamp. This paper described the design and performance of the detector and read-out system and presents some recent beamline results.

Construction of a double-radius Guinier diffractometer using Mo Kα1 radiation and a one- or two-dimensional detection system

This paper presents the design for a computer-assisted double-radius Guinier system for Mo Kα1 radiation with a cylindrically bent imaging plate and an integrated readout scanner for the recorded diffraction patterns. This quick X-ray detection technique makes new applications for the Guinier method possible. The addition of suitable components such as an optimized monochromator, a set-up for changing, moving and heating the samples and sophisticated adjustment equipment improves the diffractometer, making it a competitive in-house system for powder characterization and crystal structure determination of high standard. The commonly used scintillation tube arrangement should also be adapted to receive a multifunctional system.

Computed tomography part III: Volumetric, High-Resolution X-Ray analysis of fatigue crack closure

Although single-slice computed tomography is a useful tool in materials science and engineering, there are some materials problems that are better understood when represented with volumetric data. This article describes the use of a two-dimensional detector system to examine fatigue crack closure in an aluminum-lithium alloy.

Simultaneous energy and angle resolved ion scattering spectroscopy; first results

Low-energy ion scattering can give detailed information on the composition and structure of the outermost atomic layers. The EARISS (energy and angle resolved ion scattering spectrometer) makes a very efficient use of the scattered ions by measuring simultaneously the energy and azimuthal distributions of the scattered ions, using both a special analyzer and two-dimensional detection system. This reduces the required ion dose, and thus the damage to the surface will be orders of magnitude smaller. In order to obtain the azimuthal distribution of the scattered ions it was necessary to correct for the apparatus profile. First results showing both energy and azimuthal dependent scattering from Ni(110) are presented. Comparison of these results with ion trajectory simulations, confirms the location of the Ni atoms in the outermost layers.

Raman imaging with plasmon surface polaritons

We report on plasmon surface polariton (PSP) field-enhanced Raman spectroscopy with a two-dimensional detection system that allows microscopic imaging of ultrathin films. The technique offers a means to distinguish between coatings which are optically almost identical films but which have different Raman scattering characteristics. This is demonstrated for a multilayer system of deuterated and protonated cadmium arachidate and the results are compared with surface plasmon microscopy which only probes the optical thickness of compounds rather than their molecular structure.