WorldWideScience

Sample records for ground pixel resolution

  1. Penrose Pixels for Super-Resolution.

    Science.gov (United States)

    Ben-Ezra, M; Lin, Zhouchen; Wilburn, Bennett; Zhang, Wei

    2011-07-01

    We present a novel approach to reconstruction-based super-resolution that uses aperiodic pixel tilings, such as a Penrose tiling or a biological retina, for improved performance. To this aim, we develop a new variant of the well-known error back projection super-resolution algorithm that makes use of the exact detector model in its back projection operator for better accuracy. Pixels in our model can vary in shape and size, and there may be gaps between adjacent pixels. The algorithm applies equally well to periodic or aperiodic pixel tilings. We present analysis and extensive tests using synthetic and real images to show that our approach using aperiodic layouts substantially outperforms existing reconstruction-based algorithms for regular pixel arrays. We close with a discussion of the feasibility of manufacturing CMOS or CCD chips with pixels arranged in Penrose tilings.

  2. Pixels simultaneous detection probabilities and spatial resolution determination of pixelized detectors by means of correlation measurements

    CERN Document Server

    Grabskii, V

    2007-01-01

    A novel method to estimate the pixels simultaneous detection probability and the spatial resolution of pixelized detectors is proposed, which is based on the determination of the statistical correlations between detector neighbor pixels. The correlations are determined by means of noise variance measurement for a isolated pixels and the difference between neighbor pixels. The method is validated using images from the two different GE Senographe 2000D mammographic units. The pixelized detector has been irradiated using x-rays along its entire surface. It is shown that the pixel simultaneous detection probabilities can be estimated within accuracy 0.001 - 0.003, where the systematic error is estimated to be smaller than 0.005. The presampled two-dimensional point-spread function (PSF0) is determined using a single Gaussian and a sum of two Gaussian approximations. The obtained results for the presampled PSF0 show that the single Gaussian approximation is not appropriate, and the sum of two Gaussian approximatio...

  3. Field-portable pixel super-resolution colour microscope.

    Science.gov (United States)

    Greenbaum, Alon; Akbari, Najva; Feizi, Alborz; Luo, Wei; Ozcan, Aydogan

    2013-01-01

    Based on partially-coherent digital in-line holography, we report a field-portable microscope that can render lensfree colour images over a wide field-of-view of e.g., >20 mm(2). This computational holographic microscope weighs less than 145 grams with dimensions smaller than 17×6×5 cm, making it especially suitable for field settings and point-of-care use. In this lensfree imaging design, we merged a colorization algorithm with a source shifting based multi-height pixel super-resolution technique to mitigate 'rainbow' like colour artefacts that are typical in holographic imaging. This image processing scheme is based on transforming the colour components of an RGB image into YUV colour space, which separates colour information from brightness component of an image. The resolution of our super-resolution colour microscope was characterized using a USAF test chart to confirm sub-micron spatial resolution, even for reconstructions that employ multi-height phase recovery to handle dense and connected objects. To further demonstrate the performance of this colour microscope Papanicolaou (Pap) smears were also successfully imaged. This field-portable and wide-field computational colour microscope could be useful for tele-medicine applications in resource poor settings.

  4. Field-portable pixel super-resolution colour microscope.

    Directory of Open Access Journals (Sweden)

    Alon Greenbaum

    Full Text Available Based on partially-coherent digital in-line holography, we report a field-portable microscope that can render lensfree colour images over a wide field-of-view of e.g., >20 mm(2. This computational holographic microscope weighs less than 145 grams with dimensions smaller than 17×6×5 cm, making it especially suitable for field settings and point-of-care use. In this lensfree imaging design, we merged a colorization algorithm with a source shifting based multi-height pixel super-resolution technique to mitigate 'rainbow' like colour artefacts that are typical in holographic imaging. This image processing scheme is based on transforming the colour components of an RGB image into YUV colour space, which separates colour information from brightness component of an image. The resolution of our super-resolution colour microscope was characterized using a USAF test chart to confirm sub-micron spatial resolution, even for reconstructions that employ multi-height phase recovery to handle dense and connected objects. To further demonstrate the performance of this colour microscope Papanicolaou (Pap smears were also successfully imaged. This field-portable and wide-field computational colour microscope could be useful for tele-medicine applications in resource poor settings.

  5. All-passive pixel super-resolution of time-stretch imaging

    OpenAIRE

    Chan, Antony C. S.; Ng, Ho-Cheung; Bogaraju, Sharat C. V.; Hayden K. H. So; Lam, Edmund Y.; Tsia, Kevin K.

    2016-01-01

    Based on image encoding in a serial-temporal format, optical time-stretch imaging entails a stringent requirement of state-of-the- art fast data acquisition unit in order to preserve high image resolution at an ultrahigh frame rate --- hampering the widespread utilities of such technology. Here, we propose a pixel super-resolution (pixel-SR) technique tailored for time-stretch imaging that preserves pixel resolution at a relaxed sampling rate. It harnesses the subpixel shifts between image fr...

  6. Enhancing resolution along multiple imaging dimensions using assorted pixels.

    Science.gov (United States)

    Narasimhan, Srinivasa G; Nayar, Shree K

    2005-04-01

    Multisampled imaging is a general framework for using pixels on an image detector to simultaneously sample multiple dimensions of imaging (space, time, spectrum, brightness, polarization, etc.). The mosaic of red, green, and blue spectral filters found in most solid-state color cameras is one example of multisampled imaging. We briefly describe how multisampling can be used to explore other dimensions of imaging. Once such an image is captured, smooth reconstructions along the individual dimensions can be obtained using standard interpolation algorithms. Typically, this results in a substantial reduction of resolution (and, hence, image quality). One can extract significantly greater resolution in each dimension by noting that the light fields associated with real scenes have enormous redundancies within them, causing different dimensions to be highly correlated. Hence, multisampled images can be better interpolated using local structural models that are learned offline from a diverse set of training images. The specific type of structural models we use are based on polynomial functions of measured image intensities. They are very effective as well as computationally efficient. We demonstrate the benefits of structural interpolation using three specific applications. These are 1) traditional color imaging with a mosaic of color filters, 2) high dynamic range monochrome imaging using a mosaic of exposure filters, and 3) high dynamic range color imaging using a mosaic of overlapping color and exposure filters.

  7. Pixel readout ASIC for an APD based 2D X-ray hybrid pixel detector with sub-nanosecond resolution

    Energy Technology Data Exchange (ETDEWEB)

    Thil, Ch., E-mail: christophe.thil@ziti.uni-heidelberg.d [Heidelberg University, Institute of Computer Engineering, B6, 26, 68161 Mannheim (Germany); Baron, A.Q.R. [RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Fajardo, P. [ESRF, Polygone Scientifique Louis Neel, 6, rue Jules Horowitz, 38000 Grenoble (France); Fischer, P. [Heidelberg University, Institute of Computer Engineering, B6, 26, 68161 Mannheim (Germany); Graafsma, H. [DESY, Notkestrasse 85, 22607 Hamburg (Germany); Rueffer, R. [ESRF, Polygone Scientifique Louis Neel, 6, rue Jules Horowitz, 38000 Grenoble (France)

    2011-02-01

    The fast response and the short recovery time of avalanche photodiodes (APDs) in linear mode make those devices ideal for direct X-ray detection in applications requiring high time resolution or counting rate. In order to provide position sensitivity, the XNAP project aims at creating a hybrid pixel detector with nanosecond time resolution based on a monolithic APD sensor array with 32 x32 pixels covering about 1 cm{sup 2} active area. The readout is implemented in a pixelated front-end ASIC suited for the readout of such arrays, matched to pixels of 280{mu}mx280{mu}m size. Every single channel features a fast transimpedance amplifier, a discriminator with locally adjustable threshold and two counters with high dynamic range and counting speed able to accumulate X-ray hits with no readout dead time. Additionally, the detector can be operated in list mode by time-stamping every single event with sub-nanosecond resolution. In a first phase of the project, a 4x4 pixel test module is built to validate the conceptual design of the detector. The XNAP project is briefly presented and the performance of the readout ASIC is discussed.

  8. Wavelength scanning achieves pixel super-resolution in holographic on-chip microscopy

    Science.gov (United States)

    Luo, Wei; Göröcs, Zoltan; Zhang, Yibo; Feizi, Alborz; Greenbaum, Alon; Ozcan, Aydogan

    2016-03-01

    Lensfree holographic on-chip imaging is a potent solution for high-resolution and field-portable bright-field imaging over a wide field-of-view. Previous lensfree imaging approaches utilize a pixel super-resolution technique, which relies on sub-pixel lateral displacements between the lensfree diffraction patterns and the image sensor's pixel-array, to achieve sub-micron resolution under unit magnification using state-of-the-art CMOS imager chips, commonly used in e.g., mobile-phones. Here we report, for the first time, a wavelength scanning based pixel super-resolution technique in lensfree holographic imaging. We developed an iterative super-resolution algorithm, which generates high-resolution reconstructions of the specimen from low-resolution (i.e., under-sampled) diffraction patterns recorded at multiple wavelengths within a narrow spectral range (e.g., 10-30 nm). Compared with lateral shift-based pixel super-resolution, this wavelength scanning approach does not require any physical shifts in the imaging setup, and the resolution improvement is uniform in all directions across the sensor-array. Our wavelength scanning super-resolution approach can also be integrated with multi-height and/or multi-angle on-chip imaging techniques to obtain even higher resolution reconstructions. For example, using wavelength scanning together with multi-angle illumination, we achieved a halfpitch resolution of 250 nm, corresponding to a numerical aperture of 1. In addition to pixel super-resolution, the small scanning steps in wavelength also enable us to robustly unwrap phase, revealing the specimen's optical path length in our reconstructed images. We believe that this new wavelength scanning based pixel super-resolution approach can provide competitive microscopy solutions for high-resolution and field-portable imaging needs, potentially impacting tele-pathology applications in resource-limited-settings.

  9. Design of a 3D-IC multi-resolution digital pixel sensor

    Science.gov (United States)

    Brochard, N.; Nebhen, J.; Dubois, J.; Ginhac, D.

    2016-04-01

    This paper presents a digital pixel sensor (DPS) integrating a sigma-delta analog-to-digital converter (ADC) at pixel level. The digital pixel includes a photodiode, a delta-sigma modulation and a digital decimation filter. It features adaptive dynamic range and multiple resolutions (up to 10-bit) with a high linearity. A specific row decoder and column decoder are also designed to permit to read a specific pixel chosen in the matrix and its neighborhood of 4 x 4. Finally, a complete design with the CMOS 130 nm 3D-IC FaStack Tezzaron technology is also described, revealing a high fill-factor of about 80%.

  10. Redundant Discrete Wavelet Transform Based Super-Resolution Using Sub-Pixel Image Registration

    Science.gov (United States)

    2003-03-01

    AFIT/GE/ENG/03-18 REDUNDANT DISCRETE WAVELET TRANSFORM BASED SUPER-RESOLUTION USING SUB-PIXEL IMAGE REGISTRATION THESIS Daniel L. Ward Second...position of the United States Air Force, Department of Defense, or the United States Government. AFIT/GE/ENG/03-18 REDUNDANT DISCRETE WAVELET TRANSFORM BASED...O3-18 REDUNDANT DISCRETE WAVELET TRANSFORM BASED SUPER-RESOLUTION USING SUB-PIXEL IMAGE REGISTRATION THESIS Daniel Lee Ward, B.S.E.E. Second

  11. arXiv Time resolution of silicon pixel sensors

    CERN Document Server

    Riegler, W.

    We derive expressions for the time resolution of silicon detectors, using the Landau theory and a PAI model for describing the charge deposit of high energy particles. First we use the centroid time of the induced signal and derive analytic expressions for the three components contributing to the time resolution, namely charge deposit fluctuations, noise and fluctuations of the signal shape due to weighting field variations. Then we derive expressions for the time resolution using leading edge discrimination of the signal for various electronics shaping times. Time resolution of silicon detectors with internal gain is discussed as well.

  12. From local pixel structure to global image super-resolution: a new face hallucination framework.

    Science.gov (United States)

    Hu, Yu; Lam, Kin-Man; Qiu, Guoping; Shen, Tingzhi

    2011-02-01

    We have developed a new face hallucination framework termed from local pixel structure to global image super-resolution (LPS-GIS). Based on the assumption that two similar face images should have similar local pixel structures, the new framework first uses the input low-resolution (LR) face image to search a face database for similar example high-resolution (HR) faces in order to learn the local pixel structures for the target HR face. It then uses the input LR face and the learned pixel structures as priors to estimate the target HR face. We present a three-step implementation procedure for the framework. Step 1 searches the database for K example faces that are the most similar to the input, and then warps the K example images to the input using optical flow. Step 2 uses the warped HR version of the K example faces to learn the local pixel structures for the target HR face. An effective method for learning local pixel structures from an individual face, and an adaptive procedure for fusing the local pixel structures of different example faces to reduce the influence of warping errors, have been developed. Step 3 estimates the target HR face by solving a constrained optimization problem by means of an iterative procedure. Experimental results show that our new method can provide good performances for face hallucination, both in terms of reconstruction error and visual quality; and that it is competitive with existing state-of-the-art methods.

  13. All-passive pixel super-resolution of time-stretch imaging

    Science.gov (United States)

    Chan, Antony C. S.; Ng, Ho-Cheung; Bogaraju, Sharat C. V.; So, Hayden K. H.; Lam, Edmund Y.; Tsia, Kevin K.

    2017-03-01

    Based on image encoding in a serial-temporal format, optical time-stretch imaging entails a stringent requirement of state-of-the-art fast data acquisition unit in order to preserve high image resolution at an ultrahigh frame rate — hampering the widespread utilities of such technology. Here, we propose a pixel super-resolution (pixel-SR) technique tailored for time-stretch imaging that preserves pixel resolution at a relaxed sampling rate. It harnesses the subpixel shifts between image frames inherently introduced by asynchronous digital sampling of the continuous time-stretch imaging process. Precise pixel registration is thus accomplished without any active opto-mechanical subpixel-shift control or other additional hardware. Here, we present the experimental pixel-SR image reconstruction pipeline that restores high-resolution time-stretch images of microparticles and biological cells (phytoplankton) at a relaxed sampling rate (≈2-5 GSa/s)—more than four times lower than the originally required readout rate (20 GSa/s) — is thus effective for high-throughput label-free, morphology-based cellular classification down to single-cell precision. Upon integration with the high-throughput image processing technology, this pixel-SR time-stretch imaging technique represents a cost-effective and practical solution for large scale cell-based phenotypic screening in biomedical diagnosis and machine vision for quality control in manufacturing.

  14. Supervised Sub-Pixel Mapping for Change Detection from Remotely Sensed Images with Different Resolutions

    Directory of Open Access Journals (Sweden)

    Ke Wu

    2017-03-01

    Full Text Available Due to the relatively low temporal resolutions of high spatial resolution (HR remotely sensed images, land-cover change detection (LCCD may have to use multi-temporal images with different resolutions. The low spatial resolution (LR images often have high temporal repetition rates, but they contain a large number of mixed pixels, which may seriously limit their capability in change detection. Soft classification (SC can produce the proportional fractions of land-covers, on which sub-pixel mapping (SPM can construct fine resolution land-cover maps to reduce the low-spatial-resolution-problem to some extent. Thus, in this paper, sub-pixel land-cover change detection with the use of different resolution images (SLCCD_DR is addressed based on SC and SPM. Previously, endmember combinations within pixels are ignored in the LR image, which may result in flawed fractional differences. Meanwhile, the information of a known HR land-cover map is insignificantly treated in the SPM models, which leads to a reluctant SLCCD_DR result. In order to overcome these issues, a novel approach based on a back propagation neural network (BPNN with different resolution images (BPNN_DR is proposed in this paper. Firstly, endmember variability per pixel is considered during the SC process to ensure the high accuracy of the derived proportional fractional difference image. After that, the BPNN-based SPM model is constructed by a complete supervised framework. It takes full advantage of the prior known HR image, whether it predates or postdates the LR image, to train the BPNN, so that a sub-pixel change detection map is generated effectively. The proposed BPNN_DR is compared with four state-of-the-art methods at different scale factors. The experimental results using both synthetic data and real images demonstrated that it can outperform with a more detailed change detection map being produced.

  15. All-passive pixel super-resolution of time-stretch imaging

    CERN Document Server

    Chan, Antony C S; Bogaraju, Sharat C V; So, Hayden K H; Lam, Edmund Y; Tsia, Kevin K

    2016-01-01

    Based on image encoding in a serial-temporal format, optical time-stretch imaging entails a stringent requirement of state-of-the- art fast data acquisition unit in order to preserve high image resolution at an ultrahigh frame rate --- hampering the widespread utilities of such technology. Here, we propose a pixel super-resolution (pixel-SR) technique tailored for time-stretch imaging that preserves pixel resolution at a relaxed sampling rate. It harnesses the subpixel shifts between image frames inherently introduced by asynchronous digital sampling of the continuous time-stretch imaging process. Precise pixel registration is thus accomplished without any active opto-mechanical subpixel-shift control or other additional hardware. Here, we present the experimental pixel-SR image reconstruction pipeline that restores high-resolution time-stretch images of microparticles and biological cells (phytoplankton) at a relaxed sampling rate (approx. 2--5 GSa/s) --- more than four times lower than the originally requir...

  16. Iterative algorithm for reconstructing rotationally asymmetric surface deviation with pixel-level spatial resolution

    Science.gov (United States)

    Quan, Haiyang; Wu, Fan; Hou, Xi

    2015-10-01

    New method for reconstructing rotationally asymmetric surface deviation with pixel-level spatial resolution is proposed. It is based on basic iterative scheme and accelerates the Gauss-Seidel method by introducing an acceleration parameter. This modified Successive Over-relaxation (SOR) is effective for solving the rotationally asymmetric components with pixel-level spatial resolution, without the usage of a fitting procedure. Compared to the Jacobi and Gauss-Seidel method, the modified SOR method with an optimal relaxation factor converges much faster and saves more computational costs and memory space without reducing accuracy. It has been proved by real experimental results.

  17. Single-pixel 3D imaging with time-based depth resolution

    CERN Document Server

    Sun, Ming-Jie; Gibson, Graham M; Sun, Baoqing; Radwell, Neal; Lamb, Robert; Padgett, Miles J

    2016-01-01

    Time-of-flight three dimensional imaging is an important tool for many applications, such as object recognition and remote sensing. Unlike conventional imaging approach using pixelated detector array, single-pixel imaging based on projected patterns, such as Hadamard patterns, utilises an alternative strategy to acquire information with sampling basis. Here we show a modified single-pixel camera using a pulsed illumination source and a high-speed photodiode, capable of reconstructing 128x128 pixel resolution 3D scenes to an accuracy of ~3 mm at a range of ~5 m. Furthermore, we demonstrate continuous real-time 3D video with a frame-rate up to 12 Hz. The simplicity of the system hardware could enable low-cost 3D imaging devices for precision ranging at wavelengths beyond the visible spectrum.

  18. A silicon pixel readout ASIC with 100 ps time resolution for the NA62 experiment

    Energy Technology Data Exchange (ETDEWEB)

    Dellacasa, G; Garbolino, S; Marchetto, F; Martoiu, S; Mazza, G; Rivetti, A; Wheadon, R, E-mail: mazza@to.infn.it [INFN sez. di Torino, Via P. Giuria 1, 10125 Torino (Italy)

    2011-01-15

    The silicon tracker of the NA62 experiment requires the measurement of the particles arrival time with a resolution better than 200 ps rms and a spatial resolution of 300 {mu}m. A time measurement technique based on a Time to Amplitude Converter has been implemented in an ASIC in order to prove the possibility to integrate a TDC with resolution better than 200 ps in a pixel cell. Time-walk problem has been addressed with the use of the Constant Fraction Discriminator technique. The ASIC has been designed in a CMOS 0.13 {mu}m technology with single event upset protection of the digital logic.

  19. A 30 ps Timing Resolution for Single Photons with Multi-pixel Burle MCP-PMT

    Energy Technology Data Exchange (ETDEWEB)

    Va' vra, J.; Benitez, J.; Coleman, J.; Leith, D.W.G.S.; Mazaheri, G.; Ratcliff, B.; Schwiening, J.; /SLAC

    2006-07-05

    We have achieved {approx}30 psec single-photoelectron and {approx}12ps for multi-photoelectron timing resolution with a new 64 pixel Burle MCP-PMT with 10 micron microchannel holes. We have also demonstrated that this detector works in a magnetic field of 15kG, and achieved a single-photoelectron timing resolution of better than 60 psec. The study is relevant for a new focusing DIRC RICH detector for particle identification at future Colliders such as the super B-factory or ILC, and for future TOF techniques. This study shows that a highly pixilated MCP-PMT can deliver excellent timing resolution.

  20. Spatial and vertex resolution studies on the ATLAS Pixel Detector based on Combined Testbeam 2004 data

    CERN Document Server

    Reisinger, Ingo; Klingenberg, Reiner

    2006-01-01

    This diploma thesis deals with spatial and vertex resolution studies on the ATLAS Pixel detector based on real data taken during the Combined Testbeam period 2004 (17th May - 15th November). For the Combined Testbeam a barrel segment of the ATLAS Detector was build up and tested under real experimental conditions. Several data sets, being recorded during that time, are reconstructed by the ATLAS control framework called ATHENA. The input information for the reconstruction of the particle tracks through the Pixel Detector are the so-called spacepoints. Their uncertainty affects the resolution of the reconstructed particle tracks and thus, also the accuracy of the vertex reconstruction. Since traversing particles deposite their charge mostly (but not compellingly) within more than one pixel, all pixels corresponding to one hit have to be grouped together to a cluster. To compute the spacepoint from the cluster information two different strategies can be performed. The first one is a digital clustering, w...

  1. Sub-pixel processing for super-resolution scanning imaging system with fiber bundle coupling

    Institute of Scientific and Technical Information of China (English)

    Bowen An; Bingbin Xue; Shengda Pan; Guilin Chen

    2011-01-01

    A multilayer fiber bundle is used to couple the image in a remote sensing imaging system. The object image passes through all layers of the fiber bundle in micro-scanning mode. The malposition of adjacent layers arranged in a hexagonal pattern is at sub-pixel scale. Therefore, sub-pixel processing can be applied to improve the spatial resolution. The images coupled by the adjacent layer fibers are separated, and subsequently, the intermediate image is obtained by histogram matching based on one of the separated image called base image. Finally, the intermediate and base images are processed in the frequency domain. The malposition of the adjacent layer fiber is converted to the phase difference in Fourier transform. Considering the limited sensitivity of the experimental instruments and human sight, the image is set as a band-limited signal and the interpolation function of image fusion is found. The results indicate that a super-resolution image with ultra-high spatial resolution is obtained.%@@ A multilayer fiber bundle is used to couple the image in a remote sensing imaging system.The object image passes through all layers of the fiber bundle in micro-scanning mode.The malposition of adjacent layers arranged in a hexagonal pattern is at sub-pixel scale.

  2. A high resolution, high frame rate detector based on a microchannel plate read out with the Medipix2 counting CMOS pixel chip.

    CERN Document Server

    Mikulec, Bettina; McPhate, J B; Tremsin, A S; Siegmund, O H W; Clark, Allan G; CERN. Geneva

    2005-01-01

    The future of ground-based optical astronomy lies with advancements in adaptive optics (AO) to overcome the limitations that the atmosphere places on high resolution imaging. A key technology for AO systems on future very large telescopes are the wavefront sensors (WFS) which detect the optical phase error and send corrections to deformable mirrors. Telescopes with >30 m diameters will require WFS detectors that have large pixel formats (512x512), low noise (<3 e-/pixel) and very high frame rates (~1 kHz). These requirements have led to the idea of a bare CMOS active pixel device (the Medipix2 chip) functioning in counting mode as an anode with noiseless readout for a microchannel plate (MCP) detector and at 1 kHz continuous frame rate. First measurement results obtained with this novel detector are presented both for UV photons and beta particles.

  3. Improving detector spatial resolution using pixelated scintillators with a barrier rib structure

    Science.gov (United States)

    Liu, Langechuan; Lu, Minghui; Cao, Wanqing; Peng, Luke; Chen, Arthur

    2016-03-01

    Indirect conversion flat panel detectors (FPDs) based on amorphous silicon (a-Si) technology are widely used in digital X-ray imaging. In such FPDs a scintillator layer is used for converting X-rays into visible light photons. However, the lateral spread of these photons inside the scintillator layer reduces spatial resolution of the FPD. In this study, FPDs incorporating pixelated scintillators with a barrier rib structure were developed to limit lateral spread of light photons thereby improving spatial resolution. For the pixelated scintillator, a two-dimensional barrier rib structure was first manufactured on a substrate layer, coated with reflective materials, and filled to the rim with the scintillating material of gadolinium oxysulfide (GOS). Several scintillator samples were fabricated, with pitch size varying from 160 to 280 μm and rib height from 200 to 280 μm. The samples were directly coupled to an a-Si flat panel photodiode array with a pitch of 200 μm to convert optical photons to electronic signals. With the pixelated scintillator, the detector modulation transfer function was shown to improve significantly (by 94% at 2 cycle/mm) compared to a detector using an unstructured GOS layer. However, the prototype does show lower sensitivity due to the decrease in scintillator fill factor. The preliminary results demonstrated the feasibility of using the barrier-rib structure to improve the spatial resolution of FPDs. Such an improvement would greatly benefit nondestructive testing applications where the spatial resolution is the most important parameter. Further investigation will focus on improving the detector sensitivity and exploring its medical applications.

  4. Development of a pixel sensor with fine space-time resolution based on SOI technology for the ILC vertex detector

    Science.gov (United States)

    Ono, Shun; Togawa, Manabu; Tsuji, Ryoji; Mori, Teppei; Yamada, Miho; Arai, Yasuo; Tsuboyama, Toru; Hanagaki, Kazunori

    2017-02-01

    We have been developing a new monolithic pixel sensor with silicon-on-insulator (SOI) technology for the International Linear Collider (ILC) vertex detector system. The SOI monolithic pixel detector is realized using standard CMOS circuits fabricated on a fully depleted sensor layer. The new SOI sensor SOFIST can store both the position and timing information of charged particles in each 20×20 μm2 pixel. The position resolution is further improved by the position weighted with the charges spread to multiple pixels. The pixel also records the hit timing with an embedded time-stamp circuit. The sensor chip has column-parallel analog-to-digital conversion (ADC) circuits and zero-suppression logic for high-speed data readout. We are designing and evaluating some prototype sensor chips for optimizing and minimizing the pixel circuit.

  5. Single-pixel three-dimensional imaging with time-based depth resolution

    Science.gov (United States)

    Sun, Ming-Jie; Edgar, Matthew P.; Gibson, Graham M.; Sun, Baoqing; Radwell, Neal; Lamb, Robert; Padgett, Miles J.

    2016-07-01

    Time-of-flight three-dimensional imaging is an important tool for applications such as object recognition and remote sensing. Conventional time-of-flight three-dimensional imaging systems frequently use a raster scanned laser to measure the range of each pixel in the scene sequentially. Here we show a modified time-of-flight three-dimensional imaging system, which can use compressed sensing techniques to reduce acquisition times, whilst distributing the optical illumination over the full field of view. Our system is based on a single-pixel camera using short-pulsed structured illumination and a high-speed photodiode, and is capable of reconstructing 128 × 128-pixel resolution three-dimensional scenes to an accuracy of ~3 mm at a range of ~5 m. Furthermore, by using a compressive sampling strategy, we demonstrate continuous real-time three-dimensional video with a frame-rate up to 12 Hz. The simplicity of the system hardware could enable low-cost three-dimensional imaging devices for precision ranging at wavelengths beyond the visible spectrum.

  6. A Statistical Definition of Image Resolution Based on the Correlation of Pixels

    CERN Document Server

    Zhou, Jian-Feng

    2015-01-01

    Resolution, usually defined by the Rayleigh criterion or the Full Width at Half Maximum of a Point Spread Function, is a basic property of an image. Here, we present a new statistical definition of image resolution based on the cross-correlation properties of the pixels in an image. It is shown that the new definition of image resolution depends not only on the PSF of an imaging device, but also on the signal-to-noise ratio of the data and on the structures of an object. In an image, the resolution does not have to be uniform. Our new definition is also suitable for the interpretation of the result of a deconvolution. We illustrate this, in this paper, with a Wiener deconvolution. It is found that weak structures can be extracted from low signal-to-noise ratio data, but with low resolution; a high-resolution image was obtained from high signal-to-noise ratio data after a Wiener deconvolution. The new definition can also be used to compare various deconvolution algorithms on their processing effects, such as r...

  7. Using a pulsed laser beam to investigate the feasibility of sub-pixel position resolution with time-correlated transient signals in 3D pixelated CdZnTe detectors

    Science.gov (United States)

    Giraldo, L. Ocampo; Bolotnikov, A. E.; Camarda, G. S.; Cheng, S.; De Geronimo, G.; McGilloway, A.; Fried, J.; Hodges, D.; Hossain, A.; Ünlü, K.; Petryk, M.; Vidal, V.; Vernon, E.; Yang, G.; James, R. B.

    2017-09-01

    We evaluated the X-Y position resolution achievable in 3D pixelated detectors by processing the signal waveforms readout from neighboring pixels. In these measurements we used a focused light beam, down to 10 μm, generated by a 1 mW pulsed laser (650 nm) to carry out raster scans over selected 3×3 pixel areas, while recording the charge signals from the 9 pixels and the cathode using two synchronized digital oscilloscopes.

  8. Optimized sampling strategy of Wireless sensor network for validation of remote sensing products over heterogeneous coarse-resolution pixel

    Science.gov (United States)

    Peng, J.; Liu, Q.; Wen, J.; Fan, W.; Dou, B.

    2015-12-01

    Coarse-resolution satellite albedo products are increasingly applied in geographical researches because of their capability to characterize the spatio-temporal patterns of land surface parameters. In the long-term validation of coarse-resolution satellite products with ground measurements, the scale effect, i.e., the mismatch between point measurement and pixel observation becomes the main challenge, particularly over heterogeneous land surfaces. Recent advances in Wireless Sensor Networks (WSN) technologies offer an opportunity for validation using multi-point observations instead of single-point observation. The difficulty is to ensure the representativeness of the WSN in heterogeneous areas with limited nodes. In this study, the objective is to develop a ground-based spatial sampling strategy through consideration of the historical prior knowledge and avoidance of the information redundancy between different sensor nodes. Taking albedo as an example. First, we derive monthly local maps of albedo from 30-m HJ CCD images a 3-year period. Second, we pick out candidate points from the areas with higher temporal stability which helps to avoid the transition or boundary areas. Then, the representativeness (r) of each candidate point is evaluated through the correlational analysis between the point-specific and area-average time sequence albedo vector. The point with the highest r was noted as the new sensor point. Before electing a new point, the vector component of the selected points should be taken out from the vectors in the following correlational analysis. The selection procedure would be ceased once if the integral representativeness (R) meets the accuracy requirement. Here, the sampling method is adapted to both single-parameter and multi-parameter situations. Finally, it is shown that this sampling method has been effectively worked in the optimized layout of Huailai remote sensing station in China. The coarse resolution pixel covering this station could be

  9. PHOTOMETRIC STEREO SHAPE-AND-ALBEDO-FROM-SHADING FOR PIXEL-LEVEL RESOLUTION LUNAR SURFACE RECONSTRUCTION

    Directory of Open Access Journals (Sweden)

    W. C. Liu

    2017-07-01

    Full Text Available Shape and Albedo from Shading (SAfS techniques recover pixel-wise surface details based on the relationship between terrain slopes, illumination and imaging geometry, and the energy response (i.e., image intensity captured by the sensing system. Multiple images with different illumination geometries (i.e., photometric stereo can provide better SAfS surface reconstruction due to the increase in observations. Photometric stereo SAfS is suitable for detailed surface reconstruction of the Moon and other extra-terrestrial bodies due to the availability of photometric stereo and the less complex surface reflecting properties (i.e., albedo of the target bodies as compared to the Earth. Considering only one photometric stereo pair (i.e., two images, pixel-variant albedo is still a major obstacle to satisfactory reconstruction and it needs to be regulated by the SAfS algorithm. The illumination directional difference between the two images also becomes an important factor affecting the reconstruction quality. This paper presents a photometric stereo SAfS algorithm for pixel-level resolution lunar surface reconstruction. The algorithm includes a hierarchical optimization architecture for handling pixel-variant albedo and improving performance. With the use of Lunar Reconnaissance Orbiter Camera - Narrow Angle Camera (LROC NAC photometric stereo images, the reconstructed topography (i.e., the DEM is compared with the DEM produced independently by photogrammetric methods. This paper also addresses the effect of illumination directional difference in between one photometric stereo pair on the reconstruction quality of the proposed algorithm by both mathematical and experimental analysis. In this case, LROC NAC images under multiple illumination directions are utilized by the proposed algorithm for experimental comparison. The mathematical derivation suggests an illumination azimuthal difference of 90 degrees between two images is recommended to achieve

  10. Development and characterization of high-resolution neutron pixel detectors based on Timepix read-out chips

    Science.gov (United States)

    Krejci, F.; Zemlicka, J.; Jakubek, J.; Dudak, J.; Vavrik, D.; Köster, U.; Atkins, D.; Kaestner, A.; Soltes, J.; Viererbl, L.; Vacik, J.; Tomandl, I.

    2016-12-01

    Using a suitable isotope such as 6Li and 10B semiconductor hybrid pixel detectors can be successfully adapted for position sensitive detection of thermal and cold neutrons via conversion into energetic light ions. The adapted devices then typically provides spatial resolution at the level comparable to the pixel pitch (55 μm) and sensitive area of about few cm2. In this contribution, we describe further progress in neutron imaging performance based on the development of a large-area hybrid pixel detector providing practically continuous neutron sensitive area of 71 × 57 mm2. The measurements characterising the detector performance at the cold neutron imaging instrument ICON at PSI and high-flux imaging beam-line Neutrograph at ILL are presented. At both facilities, high-resolution high-contrast neutron radiography with the newly developed detector has been successfully applied for objects which imaging were previously difficult with hybrid pixel technology (such as various composite materials, objects of cultural heritage etc.). Further, a significant improvement in the spatial resolution of neutron radiography with hybrid semiconductor pixel detector based on the fast read-out Timepix-based detector is presented. The system is equipped with a thin planar 6LiF convertor operated effectively in the event-by-event mode enabling position sensitive detection with spatial resolution better than 10 μm.

  11. Mapping trees outside forests using high-resolution aerial imagery: a comparison of pixel- and object-based classification approaches.

    Science.gov (United States)

    Meneguzzo, Dacia M; Liknes, Greg C; Nelson, Mark D

    2013-08-01

    Discrete trees and small groups of trees in nonforest settings are considered an essential resource around the world and are collectively referred to as trees outside forests (ToF). ToF provide important functions across the landscape, such as protecting soil and water resources, providing wildlife habitat, and improving farmstead energy efficiency and aesthetics. Despite the significance of ToF, forest and other natural resource inventory programs and geospatial land cover datasets that are available at a national scale do not include comprehensive information regarding ToF in the United States. Additional ground-based data collection and acquisition of specialized imagery to inventory these resources are expensive alternatives. As a potential solution, we identified two remote sensing-based approaches that use free high-resolution aerial imagery from the National Agriculture Imagery Program (NAIP) to map all tree cover in an agriculturally dominant landscape. We compared the results obtained using an unsupervised per-pixel classifier (independent component analysis-[ICA]) and an object-based image analysis (OBIA) procedure in Steele County, Minnesota, USA. Three types of accuracy assessments were used to evaluate how each method performed in terms of: (1) producing a county-level estimate of total tree-covered area, (2) correctly locating tree cover on the ground, and (3) how tree cover patch metrics computed from the classified outputs compared to those delineated by a human photo interpreter. Both approaches were found to be viable for mapping tree cover over a broad spatial extent and could serve to supplement ground-based inventory data. The ICA approach produced an estimate of total tree cover more similar to the photo-interpreted result, but the output from the OBIA method was more realistic in terms of describing the actual observed spatial pattern of tree cover.

  12. Sub-pixel analysis to support graphic security after scanning at low resolution

    Science.gov (United States)

    Haas, Bertrand; Cordery, Robert; Gou, Hongmei; Decker, Steve

    2006-02-01

    Whether in the domain of audio, video or finance, our world tends to become increasingly digital. However, for diverse reasons, the transition from analog to digital is often much extended in time, and proceeds by long steps (and sometimes never completes). One such step is the conversion of information on analog media to digital information. We focus in this paper on the conversion (scanning) of printed documents to digital images. Analog media have the advantage over digital channels that they can harbor much imperceptible information that can be used for fraud detection and forensic purposes. But this secondary information usually fails to be retrieved during the conversion step. This is particularly relevant since the Check-21 act (Check Clearing for the 21st Century act) became effective in 2004 and allows images of checks to be handled by banks as usual paper checks. We use here this situation of check scanning as our primary benchmark for graphic security features after scanning. We will first present a quick review of the most common graphic security features currently found on checks, with their specific purpose, qualities and disadvantages, and we demonstrate their poor survivability after scanning in the average scanning conditions expected from the Check-21 Act. We will then present a novel method of measurement of distances between and rotations of line elements in a scanned image: Based on an appropriate print model, we refine direct measurements to an accuracy beyond the size of a scanning pixel, so we can then determine expected distances, periodicity, sharpness and print quality of known characters, symbols and other graphic elements in a document image. Finally we will apply our method to fraud detection of documents after gray-scale scanning at 300dpi resolution. We show in particular that alterations on legitimate checks or copies of checks can be successfully detected by measuring with sub-pixel accuracy the irregularities inherently introduced

  13. Photon-counting hexagonal pixel array CdTe detector: Spatial resolution characteristics for image-guided interventional applications

    Energy Technology Data Exchange (ETDEWEB)

    Vedantham, Srinivasan; Shrestha, Suman; Karellas, Andrew, E-mail: andrew.karellas@umassmed.edu; Shi, Linxi; Gounis, Matthew J. [Department of Radiology, University of Massachusetts Medical School, Worcester, Massachusetts 01655 (United States); Bellazzini, Ronaldo; Spandre, Gloria; Brez, Alessandro; Minuti, Massimo [Istituto Nazionale di Fisica Nucleare (INFN), Pisa 56127, Italy and Pixirad Imaging Counters s.r.l., L. Pontecorvo 3, Pisa 56127 (Italy)

    2016-05-15

    Purpose: High-resolution, photon-counting, energy-resolved detector with fast-framing capability can facilitate simultaneous acquisition of precontrast and postcontrast images for subtraction angiography without pixel registration artifacts and can facilitate high-resolution real-time imaging during image-guided interventions. Hence, this study was conducted to determine the spatial resolution characteristics of a hexagonal pixel array photon-counting cadmium telluride (CdTe) detector. Methods: A 650 μm thick CdTe Schottky photon-counting detector capable of concurrently acquiring up to two energy-windowed images was operated in a single energy-window mode to include photons of 10 keV or higher. The detector had hexagonal pixels with apothem of 30 μm resulting in pixel pitch of 60 and 51.96 μm along the two orthogonal directions. The detector was characterized at IEC-RQA5 spectral conditions. Linear response of the detector was determined over the air kerma rate relevant to image-guided interventional procedures ranging from 1.3 nGy/frame to 91.4 μGy/frame. Presampled modulation transfer was determined using a tungsten edge test device. The edge-spread function and the finely sampled line spread function accounted for hexagonal sampling, from which the presampled modulation transfer function (MTF) was determined. Since detectors with hexagonal pixels require resampling to square pixels for distortion-free display, the optimal square pixel size was determined by minimizing the root-mean-squared-error of the aperture functions for the square and hexagonal pixels up to the Nyquist limit. Results: At Nyquist frequencies of 8.33 and 9.62 cycles/mm along the apothem and orthogonal to the apothem directions, the modulation factors were 0.397 and 0.228, respectively. For the corresponding axis, the limiting resolution defined as 10% MTF occurred at 13.3 and 12 cycles/mm, respectively. Evaluation of the aperture functions yielded an optimal square pixel size of 54

  14. A sub-millimeter resolution PET detector module using a multi-pixel photon counter array.

    Science.gov (United States)

    Song, Tae Yong; Wu, Heyu; Komarov, Sergey; Siegel, Stefan B; Tai, Yuan-Chuan

    2010-05-07

    A PET block detector module using an array of sub-millimeter lutetium oxyorthosilicate (LSO) crystals read out by an array of surface-mount, semiconductor photosensors has been developed. The detector consists of a LSO array, a custom acrylic light guide, a 3 x 3 multi-pixel photon counter (MPPC) array (S10362-11-050P, Hamamatsu Photonics, Japan) and a readout board with a charge division resistor network. The LSO array consists of 100 crystals, each measuring 0.8 x 0.8 x 3 mm(3) and arranged in 0.86 mm pitches. A Monte Carlo simulation was used to aid the design and fabrication of a custom light guide to control distribution of scintillation light over the surface of the MPPC array. The output signals of the nine MPPC are multiplexed by a charge division resistor network to generate four position-encoded analog outputs. Flood image, energy resolution and timing resolution measurements were performed using standard NIM electronics. The linearity of the detector response was investigated using gamma-ray sources of different energies. The 10 x 10 array of 0.8 mm LSO crystals was clearly resolved in the flood image. The average energy resolution and standard deviation were 20.0% full-width at half-maximum (FWHM) and +/-5.0%, respectively, at 511 keV. The timing resolution of a single MPPC coupled to a LSO crystal was found to be 857 ps FWHM, and the value for the central region of detector module was 1182 ps FWHM when +/-10% energy window was applied. The nonlinear response of a single MPPC when used to read out a single LSO was observed among the corner crystals of the proposed detector module. However, the central region of the detector module exhibits significantly less nonlinearity (6.5% for 511 keV). These results demonstrate that (1) a charge-sharing resistor network can effectively multiplex MPPC signals and reduce the number of output signals without significantly degrading the performance of a PET detector and (2) a custom light guide to permit light sharing

  15. Hybrid pixel-waveform CdTe/CZT detector for use in an ultrahigh resolution MRI compatible SPECT system

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Liang, E-mail: cai7@illinois.edu [Department of Nuclear, Plasma, and Radiological Engineering, University of Illinois at Urbana Champaign, 216 Talbot Laboratory, 104 S Wrig, Urbana, Urbana, Illinois 61801 (United States); Meng, Ling-Jian [Department of Nuclear, Plasma, and Radiological Engineering, University of Illinois at Urbana Champaign, 216 Talbot Laboratory, 104 S Wrig, Urbana, Urbana, Illinois 61801 (United States)

    2013-02-21

    In this paper, we will present a new small pixel CdTe/CZT detector for sub-500 μm resolution SPECT imaging application inside MR scanner based on a recently developed hybrid pixel-waveform (HPWF) readout circuitry. The HPWF readout system consists of a 2-D multi-pixel circuitry attached to the anode pixels to provide the X–Y positions of interactions, and a high-speed digitizer to read out the pulse-waveform induced on the cathode. The digitized cathode waveform could provide energy deposition information, precise timing and depth-of-interaction information for gamma ray interactions. Several attractive features with this HPWF detector system will be discussed in this paper. To demonstrate the performance, we constructed several prototype HPWF detectors with pixelated CZT and CdTe detectors of 2–5 mm thicknesses, connected to a prototype readout system consisting of energy-resolved photon-counting ASIC for readout anode pixels and an Agilent high-speed digitizer for digitizing the cathode signals. The performances of these detectors based on HPWF are discussed in this paper.

  16. Hybrid pixel-waveform CdTe/CZT detector for use in an ultrahigh resolution MRI compatible SPECT system

    Science.gov (United States)

    Cai, Liang; Meng, Ling-Jian

    2013-02-01

    In this paper, we will present a new small pixel CdTe/CZT detector for sub-500 μm resolution SPECT imaging application inside MR scanner based on a recently developed hybrid pixel-waveform (HPWF) readout circuitry. The HPWF readout system consists of a 2-D multi-pixel circuitry attached to the anode pixels to provide the X-Y positions of interactions, and a high-speed digitizer to read out the pulse-waveform induced on the cathode. The digitized cathode waveform could provide energy deposition information, precise timing and depth-of-interaction information for gamma ray interactions. Several attractive features with this HPWF detector system will be discussed in this paper. To demonstrate the performance, we constructed several prototype HPWF detectors with pixelated CZT and CdTe detectors of 2-5 mm thicknesses, connected to a prototype readout system consisting of energy-resolved photon-counting ASIC for readout anode pixels and an Agilent high-speed digitizer for digitizing the cathode signals. The performances of these detectors based on HPWF are discussed in this paper.

  17. A Measurement of Lorentz Angle and Spatial Resolution of Radiation Hard Silicon Pixel Sensors

    CERN Document Server

    Gorelov, I; Hoeferkamp, M; Seidel, S C; Ciocio, A; Einsweiler, Kevin F; Gilchriese, M G D; Joshi, A; Kleinfelder, S A; Marchesini, R; Milgrome, O; Palaio, N; Pengg, F X; Richardson, J; Zizka, G; Ackers, M; Fischer, P; Keil, M; Meuser, S; Stockmanns, T; Treis, J; Wermes, N; Gössling, C; Hügging, F G; Wüstenfeld, J; Wunstorf, R; Barberis, D; Beccherle, R; Cervetto, M; Darbo, G; Gagliardi, G; Gemme, C; Morettini, P; Netchaeva, P; Osculati, B; Parodi, F; Rossi, L; Dao, K; Fasching, D; Blanquart, L; Breugnon, P; Calvet, D; Clemens, J C; Delpierre, P A; Hallewell, G D; Laugier, D; Mouthuy, T; Rozanov, A N; Trouilleau, C; Valin, I; Aleppo, M; Andreazza, A; Caccia, M; Lari, T; Meroni, C; Ragusa, F; Troncon, C; Vegni, G; Rohe, T; Boyd, G; Severini, H; Skubic, P L; Snow, J; Sícho, P; Tomasek, L; Vrba, V; Holder, M; Lipka, D; Ziolkowski, M; Cauz, D; D'Auria, S; del Papa, C; Grassman, H; Santi, L; Becks, K H; Gerlach, P; Grah, C; Gregor, I; Harenberg, T; Linder, C

    2002-01-01

    Silicon pixel sensors developed by the ATLAS collaboration to meet LHC requirements and to withstand hadronic irradiation to fluences of up to $10^{15} n_eq/cm^{2}$ have been evaluated using a test beam facility at CERN providing a magnetic field. The Lorentz angle was measured and found to alter from 9.0 deg. before irradiation, when the detectors operated at 150 V bias at B=1.48 T, to 3.1 deg after irradiation and operating at 600 V bias at 1.01 T. In addition to the effect due to magnetic field variation, this change is explained by the variation of the electric field inside the detectors arising from the different bias conditions. The depletion depths of irradiated sensors at various bias voltages were also measured. At 600 V bias 280 micron thick sensors depleted to ~200 micron after irradiation at the design fluence of 1 10^{15} 1 MeV n_eq/cm2 and were almost fully depleted at a fluence of 0.5 * 10^{15} 1 MeV n_eq/cm2. The spatial resolution was measured for angles of incidence between 0 deg and 30 deg....

  18. Fusion of Pixel-based and Object-based Features for Road Centerline Extraction from High-resolution Satellite Imagery

    Directory of Open Access Journals (Sweden)

    CAO Yungang

    2016-10-01

    Full Text Available A novel approach for road centerline extraction from high spatial resolution satellite imagery is proposed by fusing both pixel-based and object-based features. Firstly, texture and shape features are extracted at the pixel level, and spectral features are extracted at the object level based on multi-scale image segmentation maps. Then, extracted multiple features are utilized in the fusion framework of Dempster-Shafer evidence theory to roughly identify the road network regions. Finally, an automatic noise removing algorithm combined with the tensor voting strategy is presented to accurately extract the road centerline. Experimental results using high-resolution satellite imageries with different scenes and spatial resolutions showed that the proposed approach compared favorably with the traditional methods, particularly in the aspect of eliminating the salt noise and conglutination phenomenon.

  19. Leader Follower Formation Control of Ground Vehicles Using Dynamic Pixel Count and Inverse Perspective Mapping

    Directory of Open Access Journals (Sweden)

    S.M.Vaitheeswarana

    2014-10-01

    Full Text Available This paper deals with leader-follower formations of non-holonomic mobile robots, introducing a formation control strategy based on pixel counts using a commercial grade electro optics camera. Localization of the leader for motions along line of sight as well as the obliquely inclined directions are considered based on pixel variation of the images by referencing to two arbitrarily designated positions in the image frames. Based on an established relationship between the displacement of the camera movement along the viewing direction and the difference in pixel counts between reference points in the images, the range and the angle estimate between the follower camera and the leader is calculated. The Inverse Perspective Transform is used to account for non linear relationship between the height of vehicle in a forward facing image and its distance from the camera. The formulation is validated with experiments.

  20. The TDCpix readout ASIC: A 75 ps resolution timing front-end for the NA62 Gigatracker hybrid pixel detector

    Energy Technology Data Exchange (ETDEWEB)

    Kluge, A., E-mail: alexander.kluge@cern.ch; Aglieri Rinella, G.; Bonacini, S.; Jarron, P.; Kaplon, J.; Morel, M.; Noy, M.; Perktold, L.; Poltorak, K.

    2013-12-21

    The TDCpix is a novel pixel readout ASIC for the NA62 Gigatracker detector. NA62 is a new experiment being installed at the CERN Super Proton Synchrotron. Its Gigatracker detector shall provide on-beam tracking and time stamping of individual particles with a time resolution of 150 ps rms. It will consist of three tracking stations, each with one hybrid pixel sensor. The peak flow of particles crossing the detector modules reaches 1.27 MHz/mm{sup 2} for a total rate of about 0.75 GHz. Ten TDCpix chips will be bump-bonded to every silicon pixel sensor. Each chip shall perform time stamping of 100 M particle hits per second with a detection efficiency above 99% and a timing accuracy better than 200 ps rms for an overall three-station-setup time resolution of better than 150 ps. The TDCpix chip has been designed in a 130 nm CMOS technology. It will feature 45×40 square pixels of 300×300μm{sup 2} and a complex End of Column peripheral region including an array of TDCs based on DLLs, four high speed serializers, a low-jitter PLL, readout and control circuits. This contribution will describe the complete design of the final TDCpix ASIC. It will discuss design choices, the challenges faced and some of the lessons learned. Furthermore, experimental results from the testing of circuit prototypes will be presented. These demonstrate the achievement of key performance figures such as a time resolution of the processing chain of 75 ps rms with a laser sent to the center of the pixel and the capability of time stamping charged particles with an overall resolution below 200 ps rms. -- Highlights: • Feasibility demonstration of a silicon pixel detector with sub-ns time tagging capability. • Demonstrator detector assembly with a time resolution of 75 ps RMS with laser charge injection; 170 ps RMS with particle beam. • Design of trigger-less TDCpix ASIC with 1800 pixels, 720 TDC channels and 4 3.2 Gbit/s serializers.

  1. Achieving subpixel resolution with time-correlated transient signals in pixelated CdZnTe gamma-ray sensors using a focused laser beam (Conference Presentation)

    Science.gov (United States)

    Ocampo Giraldo, Luis A.; Bolotnikov, Aleksey E.; Camarda, Giuseppe S.; Cui, Yonggang; De Geronimo, Gianluigi; Gul, Rubi; Fried, Jack; Hossain, Anwar; Unlu, Kenan; Vernon, Emerson; Yang, Ge; James, Ralph B.

    2017-05-01

    High-resolution position-sensitive detectors have been proposed to correct response non-uniformities in Cadmium Zinc Telluride (CZT) crystals by virtually subdividing the detectors area into small voxels and equalizing responses from each voxel. 3D pixelated detectors coupled with multichannel readout electronics are the most advanced type of CZT devices offering many options in signal processing and enhancing detector performance. One recent innovation proposed for pixelated detectors is to use the induced (transient) signals from neighboring pixels to achieve high sub-pixel position resolution while keeping large pixel sizes. The main hurdle in achieving this goal is the relatively low signal induced on the neighboring pixels because of the electrostatic shielding effect caused by the collecting pixel. In addition, to achieve high position sensitivity one should rely on time-correlated transient signals, which means that digitized output signals must be used. We present the results of our studies to measure the amplitude of the pixel signals so that these can be used to measure positions of the interaction points. This is done with the processing of digitized correlated time signals measured from several adjacent pixels taking into account rise-time and charge-sharing effects. In these measurements we used a focused pulsed laser to generate a 10-micron beam at one milliwatt (650-nm wavelength) over the detector surface while the collecting pixel was moved in cardinal directions. The results include measurements that present the benefits of combining conventional pixel geometry with digital pulse processing for the best approach in achieving sub-pixel position resolution with the pixel dimensions of approximately 2 mm. We also present the sub-pixel resolution measurements at comparable energies from various gamma emitting isotopes.

  2. The TDCpix readout ASIC: A 75ps resolution timing front-end for the NA62 Gigatracker hybrid pixel detector

    CERN Document Server

    Kluge, A; Bonacini, S; Jarron, P; Kaplon, J; Morel, M; Noy, M; Perktold, L; Poltorak, K

    2013-01-01

    The TDCpix is a novel pixel readout ASIC for the NA62 Gigatracker detector. NA62 is a new experiment being installed at the CERN Super Proton Synchrotron. Its Gigatracker detector shall provide on-beam tracking and time stamping of individual particles with a time resolution of 150 ps rms. It will consist of three tracking stations, each with one hybrid pixel sensor. The peak fl ow of particles crossing the detector modules reaches 1.27 MHz/mm 2 for a total rate of about 0.75 GHz. Ten TDCpix chips will be bump-bonded to every silicon pixel sensor. Each chip shall perform time stamping of 100 M particle hits per second with a detection ef fi ciency above 99% and a timing accuracy better than 200 ps rms for an overall three-station-setup time resolution of better than 150 ps. The TDCpix chip has been designed in a 130 nm CMOS technology. It will feature 45 40 square pixels of 300 300 μ m 2 and a complex End of Column peripheral region including an array of TDCs based on DLLs, four high speed serializers, a low...

  3. 256-pixel microcalorimeter array for high-resolution γ-ray spectroscopy of mixed-actinide materials

    Energy Technology Data Exchange (ETDEWEB)

    Winkler, R., E-mail: rwinkler@lanl.gov [Los Alamos National Laboratory, Los Alamos, NM (United States); Hoover, A.S.; Rabin, M.W. [Los Alamos National Laboratory, Los Alamos, NM (United States); Bennett, D.A.; Doriese, W.B.; Fowler, J.W.; Hays-Wehle, J.; Horansky, R.D.; Reintsema, C.D.; Schmidt, D.R.; Vale, L.R.; Ullom, J.N. [National Institute of Standards and Technology, Boulder, CO (United States)

    2015-01-11

    The application of cryogenic microcalorimeter detectors to γ-ray spectroscopy allows for measurements with unprecedented energy resolution. These detectors are ideally suited for γ-ray spectroscopy applications for which the measurement quality is limited by the spectral overlap of many closely spaced transitions using conventional detector technologies. The non-destructive analysis of mixed-isotope Pu materials is one such application where the precision can be potentially improved utilizing microcalorimeter detectors compared to current state-of-the-art high-purity Ge detectors (HPGe). The LANL-NIST γ-ray spectrometer, a 256-pixel microcalorimeter array based on transition-edge sensors (TESs), was recently commissioned and used to collect data on a variety of Pu isotopic standards to characterize the instrument performance. These measurements represent the first time the simultaneous readout of all 256 pixels for measurements of mixed-isotope Pu materials has been achieved. The LANL-NIST γ-ray spectrometer has demonstrated an average pixel resolution of 55 eV full-width-at-half-maximum at 100 keV, nearly an order of magnitude better than HPGe detectors. Some challenges of the analysis of many-channel ultra-high resolution data and the techniques used to produce quality spectra for isotopic analysis will be presented. The LANL-NIST γ-ray spectrometer has also demonstrated stable operation and obtained high resolution measurements at total array event rates beyond 1 kHz. For a total event rate of 1.25 kHz, approximately 5.6 cps/pixel, a 72.2 eV average FWHM for the 103 keV photopeak of {sup 153}Gd was achieved.

  4. Efficient phase contrast imaging in STEM using a pixelated detector. Part 1: Experimental demonstration at atomic resolution

    Energy Technology Data Exchange (ETDEWEB)

    Pennycook, Timothy J., E-mail: tpennycook@gmail.com [EPSRC SuperSTEM Facility, Daresbury Laboratory, Warrington WA4 4AD (United Kingdom); Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Lupini, Andrew R. [Oak Ridge National Laboratory, Materials Science and Technology Division, Oak Ridge, TN 37830 (United States); Yang, Hao [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Murfitt, Matthew F. [Nion Co., 1102 8th St., Kirkland, WA 98033 (United States); Jones, Lewys [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Nellist, Peter D. [EPSRC SuperSTEM Facility, Daresbury Laboratory, Warrington WA4 4AD (United Kingdom); Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom)

    2015-04-15

    We demonstrate a method to achieve high efficiency phase contrast imaging in aberration corrected scanning transmission electron microscopy (STEM) with a pixelated detector. The pixelated detector is used to record the Ronchigram as a function of probe position which is then analyzed with ptychography. Ptychography has previously been used to provide super-resolution beyond the diffraction limit of the optics, alongside numerically correcting for spherical aberration. Here we rely on a hardware aberration corrector to eliminate aberrations, but use the pixelated detector data set to utilize the largest possible volume of Fourier space to create high efficiency phase contrast images. The use of ptychography to diagnose the effects of chromatic aberration is also demonstrated. Finally, the four dimensional dataset is used to compare different bright field detector configurations from the same scan for a sample of bilayer graphene. Our method of high efficiency ptychography produces the clearest images, while annular bright field produces almost no contrast for an in-focus aberration-corrected probe. - Highlights: • Ptychographic high efficiency phase contrast imaging is demonstrated in STEM. • We rely on a hardware aberration corrector to eliminate aberrations. • High efficiency is achieved by collecting all the relevant interference. • Use of a pixelated detector allows comparison of bright field modes post acquisition. • Ptychography provides the clearest images among the STEM bright field modes tested.

  5. The upGREAT 1.9 THz multi-pixel high resolution spectrometer for the SOFIA Observatory

    CERN Document Server

    Risacher, C; Stutzki, J; Huebers, H -W; Bell, A; Buchbender, C; Buechel, D; Csengeri, T; Graf, U U; Heyminck, S; Higgins, R D; Honingh, C E; Jacobs, K; Klein, B; Okada, Y; Parikka, A; Puetz, P; Reyes, N; Ricken, O; Riquelme, D; Simon, R; Wiesemeyer, H

    2016-01-01

    We present a new multi-pixel high resolution (R >10^7) spectrometer for the Stratospheric Observatory for Far-Infrared Astronomy (SOFIA). The receiver uses 2 x 7-pixel subarrays in orthogonal polarization, each in an hexagonal array around a central pixel. We present the first results for this new instrument after commissioning campaigns in May and December 2015 and after science observations performed in May 2016 . The receiver is designed to ultimately cover the full 1.8-2.5 THz frequency range but in its first implementation, the observing range was limited to observations of the [CII] line at 1.9 THz in 2015 and extended to 1.83-2.07 THz in 2016. The instrument sensitivities are state-of-the-art and the first scientific observations performed shortly after the commissioning confirm that the time efficiency for large scale imaging is improved by more than an order of magnitude as compared to single pixel receivers. An example of large scale mapping around the Horsehead Nebula is presented here illustrating...

  6. The upGREAT 1.9 THz multi-pixel high resolution spectrometer for the SOFIA Observatory

    Science.gov (United States)

    Risacher, C.; Güsten, R.; Stutzki, J.; Hübers, H.-W.; Bell, A.; Buchbender, C.; Büchel, D.; Csengeri, T.; Graf, U. U.; Heyminck, S.; Higgins, R. D.; Honingh, C. E.; Jacobs, K.; Klein, B.; Okada, Y.; Parikka, A.; Pütz, P.; Reyes, N.; Ricken, O.; Riquelme, D.; Simon, R.; Wiesemeyer, H.

    2016-10-01

    We present a new multi-pixel high resolution (R ≳ 107) spectrometer for the Stratospheric Observatory for Far-Infrared Astronomy (SOFIA). The receiver uses 2 × 7-pixel subarrays in orthogonal polarization, each in an hexagonal array around a central pixel. We present the first results for this new instrument after commissioning campaigns in May and December 2015 and after science observations performed in May 2016. The receiver is designed to ultimately cover the full 1.8-2.5 THz frequency range but in its first implementation, the observing range was limited to observations of the [CII] line at 1.9 THz in 2015 and extended to 1.83-2.07 THz in 2016. The instrument sensitivities are state-of-the-art and the first scientific observations performed shortly after the commissioning confirm that the time efficiency for large scale imaging is improved by more than an order of magnitude as compared to single pixel receivers. An example of large scale mapping around the Horsehead Nebula is presented here illustrating this improvement. The array has been added to SOFIA's instrument suite already for ongoing observing cycle 4. The datacube of the Horsehead observations is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/595/A34

  7. Development of Small-Pixel CZT Detectors for Future High-Resolution Hard X-ray Missions

    Science.gov (United States)

    Beilicke, Matthias

    Owing to recent breakthroughs in grazing incidence mirror technology, next-generation hard X-ray telescopes will achieve angular resolutions of between 5 and 10 arc seconds - about an order of magnitude better than that of the NuSTAR hard X-ray telescope. As a consequence, the next generation of hard X-ray telescopes will require pixelated hard X- ray detectors with pixels on a grid with a lattice constant of between 120 and 240 um. Additional detector requirements include a low energy threshold of less than 5 keV and an energy resolution of less than 1 keV. The science drivers for a high angular-resolution hard X-ray mission include studies and measurements of black hole spins, the cosmic evolution of super-massive black holes, AGN feedback, and the behavior of matter at very high densities. We propose a R&D research program to develop, optimize and study the performance of 100-200 um pixel pitch CdTe and Cadmium Zinc Telluride (CZT) detectors of 1-2 mm thickness. Our program aims at a comparison of the performance achieved with CdTe and CZT detectors, and the optimization of the pixel, steering grid, and guard ring anode patterns. Although these studies will use existing ASICs (Application Specific Integrated Circuits), our program also includes modest funds for the development of an ultra-low noise ASIC with a 2-D grid of readout pads that can be directly bonded to the 100-200 um pixel pitch CdTe and CZT detectors. The team includes the Washington University group (Prof. M. Beilicke and Co-I Prof. H.S.W. Krawczynski et al.), and co-investigator G. De Geronimo at Brookhaven National Laboratory (BNL). The Washington University group has a 10 year track record of innovative CZT detector R&D sponsored by the NASA Astronomy and Physics Research and Analysis (APRA) program. The accomplishments to date include the development of CZT detectors with pixel pitches between 350 um and 2.5 mm for the ProtoExist, EXIST, and X-Calibur hard X-ray missions with some of the best

  8. Upsampling range camera depth maps using high-resolution vision camera and pixel-level confidence classification

    Science.gov (United States)

    Tian, Chao; Vaishampayan, Vinay; Zhang, Yifu

    2011-03-01

    We consider the problem of upsampling a low-resolution depth map generated by a range camera, by using information from one or more additional high-resolution vision cameras. The goal is to provide an accurate high resolution depth map from the viewpoint of one of the vision cameras. We propose an algorithm that first converts the low resolution depth map into a depth/disparity map through coordinate mappings into the coordinate frame of one vision camera, then classifies the pixels into regions according to whether the range camera depth map is trustworthy, and finally refine the depth values for the pixels in the untrustworthy regions. For the last refinement step, both a method based on graph cut optimization and that based on bilateral filtering are examined. Experimental results show that the proposed methods using classification are able to upsample the depth map by a factor of 10 x 10 with much improved depth details, with significantly better accuracy comparing to those without the classification. The improvements are visually perceptible on a 3D auto-stereoscopic display.

  9. 16k pixel digital line-scan sensor with 12bit resolution and 40kS/second

    Science.gov (United States)

    Wäny, Martin; Franco, Paulo; Voltz, Stephan

    2009-02-01

    This paper presents a digital line-scan sensor in standard CMOS technology for high resolution scanning application in machine vision, mainly surface inspection of large panel and web materials. The sensor however has due to the unprecedented resolution also application potential in earth observation and motion picture context. The sensor features 16384 charge integrating pixels of 3.5um x 3.5um photo active area. Each pixel has it's own charge integrating transconductance amplifier circuit, a true correlated double sampling stage, sample & hold stage and a pixel level 13 bit linear AD converter. Readout is performed over 16 parallel digital output tap's operated at 50MHz pixel clock. The sensor generates at maximum speed a total data rate of 10.4Gbit/s. In order to maximize the integration time, data readout, AD conversion and integration can be performed simultaneously. Therefore even at the maximum line rate of 43kScans/second the integration time can be maintained at 20us. In order to accommodate for different application scenarios with very different lighting budget's, the sensors full well capacity can be programmed by means of a two step programmable gain from 3000e- to 40ke-. The prototype characterization results showed a total quantum efficiency of 72% at 625nm. With the full well capacity set to 26ke- the conversion gain was measured to be 0.13DN/e- with a read noise in dark of 1.7DN, or 12 e- dark noise equivalent. Over all DSNU is reduced to 3DN rms independent of the conversion gain by the on chip combination of CDS and digital DSNU correction. PRNU was measured according the EMVA1288 standard to 1.2% rms. The sensor is mounted on an "Invar" enforced COB board without glass cover for reduced reflections on optical interface stacks. Instead of traditional package leads SMD mounted board to board connectors are used for the electrical connections.

  10. Comparison of ultra-high-resolution parallel-hole collimator materials based on the CdTe pixelated semiconductor SPECT system

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young-Jin; Ryu, Hyun-Ju; Lee, Seung-Wan; Park, Su-Jin; Kim, Hee-Joung, E-mail: hjk1@yonsei.ac.kr

    2013-06-11

    Recently, many studies have sought to improve the sensitivity and spatial resolution of pixelated semiconductor detectors. Spatial resolution can be improved by using a pinhole or pixelated parallel-hole collimator with equal hole and pixel sizes. We compared a pinhole to a pixelated parallel-hole collimator and found that the pixelated parallel-hole collimator had higher sensitivity. Additionally, collimator materials with high absorption efficiency are often used because of their high spatial resolution. The purpose of this study was to compare the quality of images generated using a pixelated semiconductor single photon emission computed tomography (SPECT) system simulated with pixelated parallel-hole collimators of lead, tungsten, gold, and depleted uranium. We performed a simulation study of the PID 350 (Ajat Oy Ltd., Finland) CdTe pixelated semiconductor detector, which consists of small pixels (0.35×0.35 mm{sup 2}), using a Geant4 Application for Tomographic Emission (GATE) simulation. Sensitivities and spatial resolutions were measured for the four collimator materials. To evaluate overall image performance, a hot-rod phantom was designed using GATE simulation. The results showed that with lead, sensitivity was 4.25%, 6.53%, and 10.28% higher than with tungsten, gold, and depleted uranium, respectively. Spatial resolution using depleted uranium was 3.19%, 4.19%, and 8.01% better than that of gold, tungsten, and lead, respectively. Sensitivity and spatial resolution showed little difference among the four types of collimator materials tested. It was difficult to visually distinguish between the reconstructed images of the hot-rod phantom for different collimator materials. The results are promising for notable cost reductions in collimator manufacturing while avoiding impractical and rare materials.

  11. Investigating the effect of pixel size of high spatial resolution FTIR imaging for detection of colorectal cancer

    Science.gov (United States)

    Lloyd, G. R.; Nallala, J.; Stone, N.

    2016-03-01

    FTIR is a well-established technique and there is significant interest in applying this technique to medical diagnostics e.g. to detect cancer. The introduction of focal plane array (FPA) detectors means that FTIR is particularly suited to rapid imaging of biopsy sections as an adjunct to digital pathology. Until recently however each pixel in the image has been limited to a minimum of 5.5 µm which results in a comparatively low magnification image or histology applications and potentially the loss of important diagnostic information. The recent introduction of higher magnification optics gives image pixels that cover approx. 1.1 µm. This reduction in image pixel size gives images of higher magnification and improved spatial detail can be observed. However, the effect of increasing the magnification on spectral quality and the ability to discriminate between disease states is not well studied. In this work we test the discriminatory performance of FTIR imaging using both standard (5.5 µm) and high (1.1 µm) magnification for the detection of colorectal cancer and explore the effect of binning to degrade high resolution images to determine whether similar diagnostic information and performance can be obtained using both magnifications. Results indicate that diagnostic performance using high magnification may be reduced as compared to standard magnification when using existing multivariate approaches. Reduction of the high magnification data to standard magnification via binning can potentially recover some of the lost performance.

  12. Monte Carlo investigation of charge-transport effects on energy resolution and detection efficiency of pixelated CZT detectors for SPECT/PET applications.

    Science.gov (United States)

    Myronakis, Marios E; Darambara, Dimitra G

    2011-01-01

    Semiconductor detectors are increasingly considered as alternatives to scintillation crystals for nuclear imaging applications such as positron emission tomography (PET) or single photon emission computed tomography (SPECT). One of the most prominent detector materials is cadmium zinc telluride (CZT), which is currently used in several application-specific nuclear imaging systems. In this work, the charge-transport effects in pixelated CZT detectors in relation to detector pixel size and thickness are investigated for pixels sizes from 0.4 up to 1.6 mm. The determination of an optimum pixel size and thickness for use with photon energies of 140 and 511 keV, suitable for SPECT and PET studies, is attempted using photon detection efficiency and energy resolution as figures of merit. The Monte Carlo method combined with detailed finite element analysis was utilized to realistically model photon interactions in the detector and the signal generation process. The GEANT4 Application for Tomographic Emission (GATE) toolkit was used for photon irradiation and interaction simulations. The COMSOL MULTIPHYSICS software application was used to create finite element models of the detector that included charge drift, diffusion, trapping, and generation. Data obtained from the two methods were combined to generate accurate signal induction at the detector pixels. The energy resolution was calculated as the full width at half maximum of the energy spectrum photopeak. Photon detection efficiency was also calculated. The effects of charge transport within the detector and photon escape from primary pixel of interaction were investigated; the extent of diffusion to lateral pixels was also assessed. Charge transport and signal induction were affected by the position of a pixel in the detector. Edge and corner pixels were less susceptible to lateral diffusion than pixels located in the inner part of the detector. Higher detection efficiency and increased photon escape from primary

  13. Per-Pixel Coded Exposure for High-Speed and High-Resolution Imaging Using a Digital Micromirror Device Camera

    Directory of Open Access Journals (Sweden)

    Wei Feng

    2016-03-01

    Full Text Available High-speed photography is an important tool for studying rapid physical phenomena. However, low-frame-rate CCD (charge coupled device or CMOS (complementary metal oxide semiconductor camera cannot effectively capture the rapid phenomena with high-speed and high-resolution. In this paper, we incorporate the hardware restrictions of existing image sensors, design the sampling functions, and implement a hardware prototype with a digital micromirror device (DMD camera in which spatial and temporal information can be flexibly modulated. Combined with the optical model of DMD camera, we theoretically analyze the per-pixel coded exposure and propose a three-element median quicksort method to increase the temporal resolution of the imaging system. Theoretically, this approach can rapidly increase the temporal resolution several, or even hundreds, of times without increasing bandwidth requirements of the camera. We demonstrate the effectiveness of our method via extensive examples and achieve 100 fps (frames per second gain in temporal resolution by using a 25 fps camera.

  14. Per-Pixel Coded Exposure for High-Speed and High-Resolution Imaging Using a Digital Micromirror Device Camera.

    Science.gov (United States)

    Feng, Wei; Zhang, Fumin; Qu, Xinghua; Zheng, Shiwei

    2016-03-04

    High-speed photography is an important tool for studying rapid physical phenomena. However, low-frame-rate CCD (charge coupled device) or CMOS (complementary metal oxide semiconductor) camera cannot effectively capture the rapid phenomena with high-speed and high-resolution. In this paper, we incorporate the hardware restrictions of existing image sensors, design the sampling functions, and implement a hardware prototype with a digital micromirror device (DMD) camera in which spatial and temporal information can be flexibly modulated. Combined with the optical model of DMD camera, we theoretically analyze the per-pixel coded exposure and propose a three-element median quicksort method to increase the temporal resolution of the imaging system. Theoretically, this approach can rapidly increase the temporal resolution several, or even hundreds, of times without increasing bandwidth requirements of the camera. We demonstrate the effectiveness of our method via extensive examples and achieve 100 fps (frames per second) gain in temporal resolution by using a 25 fps camera.

  15. Linear least square (LLS) method for pixel-resolution analysis of polarization dependent SHG images of collagen fibrils.

    Science.gov (United States)

    Rouède, Denis; Bellanger, Jean-Jacques; Bomo, Jérémy; Baffet, Georges; Tiaho, François

    2015-05-18

    A linear least square (LLS) method is proposed to process polarization dependent SHG intensity analysis at pixel-resolution level in order to provide an analytic solution of nonlinear susceptibility χ(2) coefficients and of fibril orientation. This model is applicable to fibrils with identical orientation in the excitation volume. It has been validated on type I collagen fibrils from cell-free gel, tendon and extracellular matrix of F1 biliary epithelial cells. LLS is fast (a few hundred milliseconds for a 512 × 512 pixel image) and very easy to perform for non-expert in numerical signal processing. Theoretical simulation highlights the importance of signal to noise ratio for accurate determination of nonlinear susceptibility χ(2) coefficients. The results also suggest that, in addition to the peptide group, a second molecular nonlinear optical hyperpolarizability β contributes to the SHG signal. Finally from fibril orientation analysis, results show that F1 cells remodel extracellular matrix collagen fibrils by changing fibril orientation, which might have important physiological function in cell migration and communication.

  16. Prevalence of pure versus mixed snow cover pixels across spatial resolutions in alpine environments: implications for binary and fractional remote sensing approaches

    Science.gov (United States)

    Selkowitz, David J.; Forster, Richard; Caldwell, Megan K.

    2014-01-01

    Remote sensing of snow-covered area (SCA) can be binary (indicating the presence/absence of snow cover at each pixel) or fractional (indicating the fraction of each pixel covered by snow). Fractional SCA mapping provides more information than binary SCA, but is more difficult to implement and may not be feasible with all types of remote sensing data. The utility of fractional SCA mapping relative to binary SCA mapping varies with the intended application as well as by spatial resolution, temporal resolution and period of interest, and climate. We quantified the frequency of occurrence of partially snow-covered (mixed) pixels at spatial resolutions between 1 m and 500 m over five dates at two study areas in the western U.S., using 0.5 m binary SCA maps derived from high spatial resolution imagery aggregated to fractional SCA at coarser spatial resolutions. In addition, we used in situ monitoring to estimate the frequency of partially snow-covered conditions for the period September 2013–August 2014 at 10 60-m grid cell footprints at two study areas with continental snow climates. Results from the image analysis indicate that at 40 m, slightly above the nominal spatial resolution of Landsat, mixed pixels accounted for 25%–93% of total pixels, while at 500 m, the nominal spatial resolution of MODIS bands used for snow cover mapping, mixed pixels accounted for 67%–100% of total pixels. Mixed pixels occurred more commonly at the continental snow climate site than at the maritime snow climate site. The in situ data indicate that some snow cover was present between 186 and 303 days, and partial snow cover conditions occurred on 10%–98% of days with snow cover. Four sites remained partially snow-free throughout most of the winter and spring, while six sites were entirely snow covered throughout most or all of the winter and spring. Within 60 m grid cells, the late spring/summer transition from snow-covered to snow-free conditions lasted 17–56 days and averaged 37

  17. Position and time resolution measurements with a microchannel plate image intensifier: A comparison of monolithic and pixelated CeBr{sub 3} scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Ackermann, Ulrich, E-mail: ulrich.ackermann@unibw.de [Universität der Bundeswehr München, Institut für angewandte Physik und Messtechnik (LRT2), Werner-Heisenberg-Weg 39, 85577 Neubiberg (Germany); Eschbaumer, Stephan, E-mail: stephan.eschbaumer@unibw.de [Universität der Bundeswehr München, Institut für angewandte Physik und Messtechnik (LRT2), Werner-Heisenberg-Weg 39, 85577 Neubiberg (Germany); Bergmaier, Andreas, E-mail: andreas.bergmaier@unibw.de [Universität der Bundeswehr München, Institut für angewandte Physik und Messtechnik (LRT2), Werner-Heisenberg-Weg 39, 85577 Neubiberg (Germany); Egger, Werner, E-mail: werner.egger@unibw.de [Universität der Bundeswehr München, Institut für angewandte Physik und Messtechnik (LRT2), Werner-Heisenberg-Weg 39, 85577 Neubiberg (Germany); Sperr, Peter, E-mail: peter.sperr@unibw.de [Universität der Bundeswehr München, Institut für angewandte Physik und Messtechnik (LRT2), Werner-Heisenberg-Weg 39, 85577 Neubiberg (Germany); Greubel, Christoph, E-mail: christoph.greubel@unibw.de [Universität der Bundeswehr München, Institut für angewandte Physik und Messtechnik (LRT2), Werner-Heisenberg-Weg 39, 85577 Neubiberg (Germany); and others

    2016-07-01

    To perform Four Dimensional Age Momentum Correlation measurements in the near future, where one obtains the positron lifetime in coincidence with the three dimensional momentum of the electron annihilating with the positron, we have investigated the time and position resolution of two CeBr{sub 3} scintillators (monolithic and an array of pixels) using a Photek IPD340/Q/BI/RS microchannel plate image intensifier. The microchannel plate image intensifier has an active diameter of 40 mm and a stack of two microchannel plates in chevron configuration. The monolithic CeBr{sub 3} scintillator was cylindrically shaped with a diameter of 40 mm and a height of 5 mm. The pixelated scintillator array covered the whole active area of the microchannel plate image intensifier and the shape of each pixel was 2.5·2.5·8 mm{sup 3} with a pixel pitch of 3.3 mm. For the monolithic setup the measured mean single time resolution was 330 ps (FWHM) at a gamma energy of 511 keV. No significant dependence on the position was detected. The position resolution at the center of the monolithic scintillator was about 2.5 mm (FWHM) at a gamma energy of 662 keV. The single time resolution of the pixelated crystal setup reached 320 ps (FWHM) in the region of the center of the active area of the microchannel plate image intensifier. The position resolution was limited by the cross-section of the pixels. The gamma energy for the pixel setup measurements was 511 keV.

  18. Studying Spatial Resolution of CZT Detectors Using Sub-Pixel Positioning for SPECT

    Science.gov (United States)

    Montémont, Guillaume; Lux, Silvère; Monnet, Olivier; Stanchina, Sylvain; Verger, Loïck

    2014-10-01

    CZT detectors are the basic building block of a variety of new SPECT systems. Their modularity allows adapting system architecture to specific applications such as cardiac, breast, brain or small animal imaging. In semiconductors, a high number of electron-hole pairs is produced by a single interaction. This direct conversion process allows better energy and spatial resolutions than usual scintillation detectors based on NaI(Tl). However, it remains often unclear if SPECT imaging can really benefit of that performance gain. We investigate the system performance of a detection module, which is based on 5 mm thick CZT with a segmented anode having a 2.5 mm pitch by simulation and experimentation. This pitch allows an easy assembly of the crystal on the readout board and limits the space occupied by electronics without significantly degrading energy and spatial resolution.

  19. Preliminary test results of a new high-energy-resolution silicon and CdZnTe pixel detectors for application to x-ray astronomy

    Science.gov (United States)

    Sushkov, V. V.; Hamilton, William J.; Hurley, Kevin; Maeding, Dale G.; Ogelman, Hakki; Paulos, Robert J.; Puetter, Richard C.; Tumer, Tumay O.; Zweerink, Jeffrey

    1999-10-01

    New, high spatial resolution CdZnTe (CZT) and silicon (Si) pixel detectors are highly suitable for x-ray astronomy. These detectors are planned for use in wide field of view, imaging x-ray, and low energy gamma-ray all-sky monitor (AXGAM) in a future space mission. The high stopping power of CZT detectors combined with low-noise front-end readout makes possible an order of magnitude improvement in spatial and energy resolution in x-ray detection. The AXGAM instrument will be built in the form of a fine coded aperture placed over two-dimensional, high spatial resolution and low energy threshold CZT pixel detector array. The preliminary result of CZT and silicon pixel detector test with low-noise readout electronics system are presented. These detectors may also be used with or without modification for medical and industrial imaging.

  20. Pixel detectors

    CERN Document Server

    Passmore, M S

    2001-01-01

    positions on the detector. The loss of secondary electrons follows the profile of the detector and increases with higher energy ions. studies of the spatial resolution predict a value of 5.3 lp/mm. The image noise in photon counting systems is investigated theoretically and experimentally and is shown to be given by Poisson statistics. The rate capability of the LAD1 was measured to be 250 kHz per pixel. Theoretical and experimental studies of the difference in contrast for ideal charge integrating and photon counting imaging systems were carried out. It is shown that the contrast differs and that for the conventional definition (contrast = (background - signal)/background) the photon counting device will, in some cases, always give a better contrast than the integrating system. Simulations in MEDICI are combined with analytical calculations to investigate charge collection efficiencies (CCE) in semiconductor detectors. Different pixel sizes and biasing conditions are considered. The results show charge shari...

  1. A 1,000 Frames/s Programmable Vision Chip with Variable Resolution and Row-Pixel-Mixed Parallel Image Processors

    Directory of Open Access Journals (Sweden)

    Nanjian Wu

    2009-07-01

    Full Text Available A programmable vision chip with variable resolution and row-pixel-mixed parallel image processors is presented. The chip consists of a CMOS sensor array, with row-parallel 6-bit Algorithmic ADCs, row-parallel gray-scale image processors, pixel-parallel SIMD Processing Element (PE array, and instruction controller. The resolution of the image in the chip is variable: high resolution for a focused area and low resolution for general view. It implements gray-scale and binary mathematical morphology algorithms in series to carry out low-level and mid-level image processing and sends out features of the image for various applications. It can perform image processing at over 1,000 frames/s (fps. A prototype chip with 64 × 64 pixels resolution and 6-bit gray-scale image is fabricated in 0.18 mm Standard CMOS process. The area size of chip is 1.5 mm × 3.5 mm. Each pixel size is 9.5 μm × 9.5 μm and each processing element size is 23 μm × 29 μm. The experiment results demonstrate that the chip can perform low-level and mid-level image processing and it can be applied in the real-time vision applications, such as high speed target tracking.

  2. Comparison Effectiveness of Pixel Based Classification and Object Based Classification Using High Resolution Image In Floristic Composition Mapping (Study Case: Gunung Tidar Magelang City)

    Science.gov (United States)

    Ardha Aryaguna, Prama; Danoedoro, Projo

    2016-11-01

    Developments of analysis remote sensing have same way with development of technology especially in sensor and plane. Now, a lot of image have high spatial and radiometric resolution, that's why a lot information. Vegetation object analysis such floristic composition got a lot advantage of that development. Floristic composition can be interpreted using a lot of method such pixel based classification and object based classification. The problems for pixel based method on high spatial resolution image are salt and paper who appear in result of classification. The purpose of this research are compare effectiveness between pixel based classification and object based classification for composition vegetation mapping on high resolution image Worldview-2. The results show that pixel based classification using majority 5×5 kernel windows give the highest accuracy between another classifications. The highest accuracy is 73.32% from image Worldview-2 are being radiometric corrected level surface reflectance, but for overall accuracy in every class, object based are the best between another methods. Reviewed from effectiveness aspect, pixel based are more effective then object based for vegetation composition mapping in Tidar forest.

  3. Lensfree on-chip tomographic microscopy employing multi-angle illumination and pixel super-resolution.

    Science.gov (United States)

    Isikman, Serhan O; Bishara, Waheb; Ozcan, Aydogan

    2012-08-16

    Tomographic imaging has been a widely used tool in medicine as it can provide three-dimensional (3D) structural information regarding objects of different size scales. In micrometer and millimeter scales, optical microscopy modalities find increasing use owing to the non-ionizing nature of visible light, and the availability of a rich set of illumination sources (such as lasers and light-emitting-diodes) and detection elements (such as large format CCD and CMOS detector-arrays). Among the recently developed optical tomographic microscopy modalities, one can include optical coherence tomography, optical diffraction tomography, optical projection tomography and light-sheet microscopy. These platforms provide sectional imaging of cells, microorganisms and model animals such as C. elegans, zebrafish and mouse embryos. Existing 3D optical imagers generally have relatively bulky and complex architectures, limiting the availability of these equipments to advanced laboratories, and impeding their integration with lab-on-a-chip platforms and microfluidic chips. To provide an alternative tomographic microscope, we recently developed lensfree optical tomography (LOT) as a high-throughput, compact and cost-effective optical tomography modality. LOT discards the use of lenses and bulky optical components, and instead relies on multi-angle illumination and digital computation to achieve depth-resolved imaging of micro-objects over a large imaging volume. LOT can image biological specimen at a spatial resolution of <1 μm x <1 μm x <3 μm in the x, y and z dimensions, respectively, over a large imaging volume of 15-100 mm(3), and can be particularly useful for lab-on-a-chip platforms.

  4. The Design and Implementation in $0.13\\mu m$ CMOS of an Algorithm Permitting Spectroscopic Imaging with High Spatial Resolution for Hybrid Pixel Detectors

    CERN Document Server

    Ballabriga, Rafael; Vilasís-Cardona, Xavier

    2009-01-01

    Advances in pixel detector technology are opening up new possibilities in many fields of science. Modern High Energy Physics (HEP) experiments use pixel detectors in tracking systems where excellent spatial resolution, precise timing and high signal-to-noise ratio are required for accurate and clean track reconstruction. Many groups are working worldwide to adapt the hybrid pixel technology to other fields such as medical X-ray radiography, protein structure analysis or neutron imaging. The Medipix3 chip is a 256x256 channel hybrid pixel detector readout chip working in Single Photon Counting Mode. It has been developed with a new front-end architecture aimed at eliminating the spectral distortion produced by charge diffusion in highly segmented semiconductor detectors. In the new architecture neighbouring pixels communicate with one another. Charges can be summed event-by-event and the incoming quantum can be assigned as a single hit to the pixel with the biggest charge deposit. In the case where incoming X-...

  5. The Design and Implementation in $0.13\\mu m$ CMOS of an Algorithm Permitting Spectroscopic Imaging with High Spatial Resolution for Hybrid Pixel Detectors

    CERN Document Server

    Ballabriga, Rafael; Vilasís-Cardona, Xavier

    2009-01-01

    Advances in pixel detector technology are opening up new possibilities in many fields of science. Modern High Energy Physics (HEP) experiments use pixel detectors in tracking systems where excellent spatial resolution, precise timing and high signal-to-noise ratio are required for accurate and clean track reconstruction. Many groups are working worldwide to adapt the hybrid pixel technology to other fields such as medical X-ray radiography, protein structure analysis or neutron imaging. The Medipix3 chip is a 256x256 channel hybrid pixel detector readout chip working in Single Photon Counting Mode. It has been developed with a new front-end architecture aimed at eliminating the spectral distortion produced by charge diffusion in highly segmented semiconductor detectors. In the new architecture neighbouring pixels communicate with one another. Charges can be summed event-by-event and the incoming quantum can be assigned as a single hit to the pixel with the biggest charge deposit. In the case where incoming X-...

  6. Effects of Per-Pixel Variability on Uncertainties in Bathymetric Retrievals from High-Resolution Satellite Images

    Directory of Open Access Journals (Sweden)

    Elizabeth J. Botha

    2016-05-01

    Full Text Available Increased sophistication of high spatial resolution multispectral satellite sensors provides enhanced bathymetric mapping capability. However, the enhancements are counter-acted by per-pixel variability in sunglint, atmospheric path length and directional effects. This case-study highlights retrieval errors from images acquired at non-optimal geometrical combinations. The effects of variations in the environmental noise on water surface reflectance and the accuracy of environmental variable retrievals were quantified. Two WorldView-2 satellite images were acquired, within one minute of each other, with Image 1 placed in a near-optimal sun-sensor geometric configuration and Image 2 placed close to the specular point of the Bidirectional Reflectance Distribution Function (BRDF. Image 2 had higher total environmental noise due to increased surface glint and higher atmospheric path-scattering. Generally, depths were under-estimated from Image 2, compared to Image 1. A partial improvement in retrieval error after glint correction of Image 2 resulted in an increase of the maximum depth to which accurate depth estimations were returned. This case-study indicates that critical analysis of individual images, accounting for the entire sun elevation and azimuth and satellite sensor pointing and geometry as well as anticipated wave height and direction, is required to ensure an image is fit for purpose for aquatic data analysis.

  7. Performance evaluation of high-resolution square parallel-hole collimators with a CZT room temperature pixelated semiconductor SPECT system: a Monte Carlo simulation study

    Science.gov (United States)

    Lee, Y.; Kang, W.

    2015-07-01

    The pixelated semiconductor based on cadmium zinc telluride (CZT) is a promising imaging device that provides many benefits compared with conventional scintillation detectors. By using a high-resolution square parallel-hole collimator with a pixelated semiconductor detector, we were able to improve both sensitivity and spatial resolution. Here, we present a simulation of a CZT pixleated semiconductor single-photon emission computed tomography (SPECT) system with a high-resolution square parallel-hole collimator using various geometric designs of 0.5, 1.0, 1.5, and 2.0 mm X-axis hole size. We performed a simulation study of the eValuator-2500 (eV Microelectronics Inc., Saxonburg, PA, U.S.A.) CZT pixelated semiconductor detector using a Geant4 Application for Tomographic Emission (GATE). To evaluate the performances of these systems, the sensitivity and spatial resolution was evaluated. Moreover, to evaluate the overall performance of the imaging system, a hot-rod phantom was designed. Our results showed that the average sensitivity of the 2.0 mm collimator X-axis hole size was 1.34, 1.95, and 3.92 times higher than that of the 1.5, 1.0, and 0.5 mm collimator X-axis hole size, respectively. Also, the average spatial resolution of the 0.5 mm collimator X-axis hole size was 28.69, 44.65, and 55.73% better than that of the 1.0, 1.5, and 2.0 mm collimator X-axis hole size, respectively. We discuss the high-resolution square parallel-hole collimator of various collimator geometric designs and our evaluations. In conclusion, we have successfully designed a high-resolution square parallel-hole collimator with a CZT pixelated semiconductor SPECT system.

  8. DESIGN OF DYADIC-INTEGER-COEFFICIENTS BASED BI-ORTHOGONAL WAVELET FILTERS FOR IMAGE SUPER-RESOLUTION USING SUB-PIXEL IMAGE REGISTRATION

    Directory of Open Access Journals (Sweden)

    P.B. Chopade

    2014-05-01

    Full Text Available This paper presents image super-resolution scheme based on sub-pixel image registration by the design of a specific class of dyadic-integer-coefficient based wavelet filters derived from the construction of a half-band polynomial. First, the integer-coefficient based half-band polynomial is designed by the splitting approach. Next, this designed half-band polynomial is factorized and assigned specific number of vanishing moments and roots to obtain the dyadic-integer coefficients low-pass analysis and synthesis filters. The possibility of these dyadic-integer coefficients based wavelet filters is explored in the field of image super-resolution using sub-pixel image registration. The two-resolution frames are registered at a specific shift from one another to restore the resolution lost by CCD array of camera. The discrete wavelet transform (DWT obtained from the designed coefficients is applied on these two low-resolution images to obtain the high resolution image. The developed approach is validated by comparing the quality metrics with existing filter banks.

  9. SHAPE AND ALBEDO FROM SHADING (SAfS FOR PIXEL-LEVEL DEM GENERATION FROM MONOCULAR IMAGES CONSTRAINED BY LOW-RESOLUTION DEM

    Directory of Open Access Journals (Sweden)

    B. Wu

    2016-06-01

    Full Text Available Lunar topographic information, e.g., lunar DEM (Digital Elevation Model, is very important for lunar exploration missions and scientific research. Lunar DEMs are typically generated from photogrammetric image processing or laser altimetry, of which photogrammetric methods require multiple stereo images of an area. DEMs generated from these methods are usually achieved by various interpolation techniques, leading to interpolation artifacts in the resulting DEM. On the other hand, photometric shape reconstruction, e.g., SfS (Shape from Shading, extensively studied in the field of Computer Vision has been introduced to pixel-level resolution DEM refinement. SfS methods have the ability to reconstruct pixel-wise terrain details that explain a given image of the terrain. If the terrain and its corresponding pixel-wise albedo were to be estimated simultaneously, this is a SAfS (Shape and Albedo from Shading problem and it will be under-determined without additional information. Previous works show strong statistical regularities in albedo of natural objects, and this is even more logically valid in the case of lunar surface due to its lower surface albedo complexity than the Earth. In this paper we suggest a method that refines a lower-resolution DEM to pixel-level resolution given a monocular image of the coverage with known light source, at the same time we also estimate the corresponding pixel-wise albedo map. We regulate the behaviour of albedo and shape such that the optimized terrain and albedo are the likely solutions that explain the corresponding image. The parameters in the approach are optimized through a kernel-based relaxation framework to gain computational advantages. In this research we experimentally employ the Lunar-Lambertian model for reflectance modelling; the framework of the algorithm is expected to be independent of a specific reflectance model. Experiments are carried out using the monocular images from Lunar Reconnaissance

  10. Shape and Albedo from Shading (SAfS) for Pixel-Level dem Generation from Monocular Images Constrained by Low-Resolution dem

    Science.gov (United States)

    Wu, Bo; Chung Liu, Wai; Grumpe, Arne; Wöhler, Christian

    2016-06-01

    Lunar topographic information, e.g., lunar DEM (Digital Elevation Model), is very important for lunar exploration missions and scientific research. Lunar DEMs are typically generated from photogrammetric image processing or laser altimetry, of which photogrammetric methods require multiple stereo images of an area. DEMs generated from these methods are usually achieved by various interpolation techniques, leading to interpolation artifacts in the resulting DEM. On the other hand, photometric shape reconstruction, e.g., SfS (Shape from Shading), extensively studied in the field of Computer Vision has been introduced to pixel-level resolution DEM refinement. SfS methods have the ability to reconstruct pixel-wise terrain details that explain a given image of the terrain. If the terrain and its corresponding pixel-wise albedo were to be estimated simultaneously, this is a SAfS (Shape and Albedo from Shading) problem and it will be under-determined without additional information. Previous works show strong statistical regularities in albedo of natural objects, and this is even more logically valid in the case of lunar surface due to its lower surface albedo complexity than the Earth. In this paper we suggest a method that refines a lower-resolution DEM to pixel-level resolution given a monocular image of the coverage with known light source, at the same time we also estimate the corresponding pixel-wise albedo map. We regulate the behaviour of albedo and shape such that the optimized terrain and albedo are the likely solutions that explain the corresponding image. The parameters in the approach are optimized through a kernel-based relaxation framework to gain computational advantages. In this research we experimentally employ the Lunar-Lambertian model for reflectance modelling; the framework of the algorithm is expected to be independent of a specific reflectance model. Experiments are carried out using the monocular images from Lunar Reconnaissance Orbiter (LRO

  11. ENHANCING GROUND RESOLUTION OF TM6 BASED ON MULTI-VARIATE REGRESSION MODEL AND SEMI-VARIOGRAM FUNCTION

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    It is well known that Landsat TM images are the most widely usedremote sensing data in various fields.Usually,it has 7 different electromagnetic spectrum bands,among which the sixth one has much lower ground resolution compared with the other six bands.Nevertheless,it is useful in the study of rock spectrum reflection,geo-thermal resources exploration,etc.To improve the ground resolution of TM6 to the level as that of the other six bands is a problem .This paper presents an algorithm based on the combination of multi-variate regression model with semi-variogram function which can improve the ground resolution of TM6 by "fusing" the data of other six bands.It includes the following main steps: (1) testing the correlation between TM6 and one of TM1-5,7.If the correlation coefficient between TM6 and another one is greater than a given threshold value,then select the band to the regression analysis as an argument.(2) calculating the size of the template window within which some parameters needed by the regression model will be calculated; (3) replacing the original pixel values of TM6 by those obtained by regression analysis; (4) using image entropy as a measurement to evaluate the quality of the fused image of TM6.The basic mechanism of the algorithm is discussed and the V C++ program for implementing this algorithm is also presented.A simple application example is given in the last part of this paper,showing the effectiveness of the algorithm.

  12. Development of an Ultrahigh Resolution Block Detector Based on 0.4 mm Pixel Ce:GAGG Scintillators and a Silicon Photomultiplier Array

    Science.gov (United States)

    Yamamoto, Seiichi; Yeom, Jung Yeol; Kamada, Kei; Endo, Takanori; Levin, Craig S.

    2013-12-01

    Ce doped Gd3Al2Ga3O12 (Ce:GAGG) is a newly developed single-crystal scintillator which has a large light output and longer emission light wavelength. The longer wavelength of the scintillation photons will produce a larger signal when coupled to typical silicon photomultiplier (Si-PM) as the quantum efficiency of semiconductor based photodetector is generally higher for light with longer wavelength. A block detector with higher spatial resolution may thus be realized by combining Ce:GAGG with Si-PM arrays. To achieve the highest possible spatial resolution for PET and SPECT detectors, we developed an ultrahigh resolution block detector using 0.4 mm × 0.4 mm × 5 mm Ce:GAGG pixels assembled to form a 24 × 24 matrix that is coupled to an Si-PM array and evaluated the performance. All Ce:GAGG pixels were separated in the 2-dimensional position histograms for Cs-137 (662 keV) gamma photons with an average peak-to-valley (P/V) ratio of 2.4. The energy resolution was 21.6% FWHM for Cs-137 (662 keV) and 23.8% for Co-57 (122 keV) gamma photons. Since Ce:GAGG does not contain naturally occurring radioisotope (Lu), beta-gamma true coincidences can be avoided and randoms are reduced when used for PET detectors. Furthermore, this property, together with its high light output and good intrinsic energy resolution, make the scintillator suited for SPECT detectors. An ultrahigh resolution PET/SPECT hybrid system might be an interesting application using Ce:GAGG/Si-PM block detectors.

  13. High Resolution Geological Site Characterization Utilizing Ground Motion Data

    Science.gov (United States)

    1992-06-26

    of the Loma Prieta earthquake. haracicri/aion demonstrate the need for the separation of stochastic and The results of our small field experiments...Array studies of ground Aki, K.. and P. Richards, Quantitative Seismology. Theory and Methods, motions using aftershocks from the Loma Prieta ...Zone with Complete Seismograms is by Bogaards and Stump. This work documents the separation of stochastic and deterministic wave propagation effects in

  14. Observing Io at high resolution from the ground with LBT

    Science.gov (United States)

    Conrad, A.; de Pater, I.; Kürster, M.; Herbst, T.; Kaltenegger, L.; Skrutskie, M.; Hinz, P.

    2011-10-01

    LINC-NIRVANA (LN) is an imaging Fizeau interferometer, with wavelength coverage from 1.1 to 2.4 microns, scheduled for first light on the Large Binocular Telescope (LBT) in 2014. The classical on-axis AO mode of LN, called LINC mode will provide solar system researchers with 15, or in some cases even 10, milliarcsecond spatial resolution. Several projects are planned for using LINC to observe features on Jupiter's volcanic moon Io.

  15. The Kepler Pixel Response Function

    CERN Document Server

    Bryson, Stephen T; Jenkins, Jon M; Chandrasekaran, Hema; Klaus, Todd; Caldwell, Douglas A; Gilliland, Ronald L; Haas, Michael R; Dotson, Jessie L; Koch, David G; Borucki, William J

    2010-01-01

    Kepler seeks to detect sequences of transits of Earth-size exoplanets orbiting Solar-like stars. Such transit signals are on the order of 100 ppm. The high photometric precision demanded by Kepler requires detailed knowledge of how the Kepler pixels respond to starlight during a nominal observation. This information is provided by the Kepler pixel response function (PRF), defined as the composite of Kepler's optical point spread function, integrated spacecraft pointing jitter during a nominal cadence and other systematic effects. To provide sub-pixel resolution, the PRF is represented as a piecewise-continuous polynomial on a sub-pixel mesh. This continuous representation allows the prediction of a star's flux value on any pixel given the star's pixel position. The advantages and difficulties of this polynomial representation are discussed, including characterization of spatial variation in the PRF and the smoothing of discontinuities between sub-pixel polynomial patches. On-orbit super-resolution measurement...

  16. Pixel Experiments

    DEFF Research Database (Denmark)

    Petersen, Kjell Yngve; Søndergaard, Karin; Augustesen, Christina

    2015-01-01

    Pixel Experiments The term pixel is traditionally defined as any of the minute elements that together constitute a larger context or image. A pixel has its own form and is the smallest unit seen within a larger structure. In working with the potentials of LED technology in architectural lighting...... design it became relevant to investigate the use of LEDs as the physical equivalent of a pixel as a design approach. In this book our interest has been in identifying how the qualities of LEDs can be used in lighting applications. With experiences in the planning and implementation of architectural...... elucidate and exemplify already well-known problems in relation to the experience of vertical and horizontal lighting. Pixel Experiments exist as a synergy between speculative test setups and lighting design in practice. This book is one of four books that is published in connection with the research...

  17. Continued Development of Small-Pixel CZT and CdTe Detectors for Future High-Angular-Resolution Hard X-ray Missions

    Science.gov (United States)

    Krawczynski, Henric

    The Nuclear Spectroscopic Telescope Array (NuSTAR) Small Explorer Mission was launched in June 2012 and has demonstrated the technical feasibility and high scientific impact of hard X-ray astronomy. We propose to continue our current R&D program to develop finely pixelated semiconductor detectors and the associated readout electronics for the focal plane of a NuSTAR follow-up mission. The detector-ASIC (Application Specific Integrated Circuit) package will be ideally matched to the new generation of low-cost, low-mass X-ray mirrors which achieve an order of magnitude better angular resolution than the NuSTAR mirrors. As part of this program, the Washington University group will optimize the contacts of 2x2 cm^2 footprint Cadmium Zinc Telluride (CZT) and Cadmium Telluride (CdTe) detectors contacted with 100x116 hexagonal pixels at a next-neighbor pitch of 200 microns. The Brookhaven National Laboratory group will design, fabricate, and test the next generation of the HEXID ASIC matched to the new X-ray mirrors and the detectors, providing a low-power 100x116 channel ASIC with extremely low readout noise (i.e. with a root mean square noise of 13 electrons). The detectors will be tested with radioactive sources and in the focal plane of high-angular-resolution X-ray mirrors at the X-ray beam facilities at the Goddard and Marshall Space Flight Centers.

  18. Pixel Detectors

    OpenAIRE

    Wermes, Norbert

    2005-01-01

    Pixel detectors for precise particle tracking in high energy physics have been developed to a level of maturity during the past decade. Three of the LHC detectors will use vertex detectors close to the interaction point based on the hybrid pixel technology which can be considered the state of the art in this field of instrumentation. A development period of almost 10 years has resulted in pixel detector modules which can stand the extreme rate and timing requirements as well as the very harsh...

  19. An Algorithm in VC-++ for Improving Ground Resolution of TM Band 6

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    @@It is well known that Landsat TM images and remotesensing data sets are widely used in the geological fields.There are 7 different bands of wavelength, of which the sixth one has a much lower ground resolution compared with those of the other six bands. Nevertheless, the Landsat TM images are of important significance of the rock spectrum reflection and geothermal exploration. The raising of the ground resolution of TM band 6 to those of the other bands is not only in teresting but also valuable. This paper illustrates an algo rithm for the increase of ground resolution of the band 6 that is feasible in the following 5 steps, based on the combination of multi-variable regression with semi variogram and on the fusion of the data from other six bands: (1) Testing the correlation between band 6andoneof bands 1-5, 7.

  20. Extensive simulation studies on the reconstructed image resolution of a position sensitive detector based on pixelated CdTe crystals

    CERN Document Server

    Zachariadou, K; Kaissas, I; Seferlis, S; Lambropoulos, C; Loukas, D; Potiriadis, C

    2011-01-01

    We present results on the reconstructed image resolution of a position sensitive radiation instrument (COCAE) based on extensive simulation studies. The reconstructed image resolution has been investigated in a wide range of incident photon energies emitted by point-like sources located at different source-to-detector distances on and off the detector's symmetry axis. The ability of the detector to distinguish multiple radioactive sources observed simultaneously is investigating by simulating point-like sources of different energies located on and off the detector's symmetry axis and at different positions

  1. PSICIC: noise and asymmetry in bacterial division revealed by computational image analysis at sub-pixel resolution.

    Directory of Open Access Journals (Sweden)

    Jonathan M Guberman

    2008-11-01

    Full Text Available Live-cell imaging by light microscopy has demonstrated that all cells are spatially and temporally organized. Quantitative, computational image analysis is an important part of cellular imaging, providing both enriched information about individual cell properties and the ability to analyze large datasets. However, such studies are often limited by the small size and variable shape of objects of interest. Here, we address two outstanding problems in bacterial cell division by developing a generally applicable, standardized, and modular software suite termed Projected System of Internal Coordinates from Interpolated Contours (PSICIC that solves common problems in image quantitation. PSICIC implements interpolated-contour analysis for accurate and precise determination of cell borders and automatically generates internal coordinate systems that are superimposable regardless of cell geometry. We have used PSICIC to establish that the cell-fate determinant, SpoIIE, is asymmetrically localized during Bacillus subtilis sporulation, thereby demonstrating the ability of PSICIC to discern protein localization features at sub-pixel scales. We also used PSICIC to examine the accuracy of cell division in Esherichia coli and found a new role for the Min system in regulating division-site placement throughout the cell length, but only prior to the initiation of cell constriction. These results extend our understanding of the regulation of both asymmetry and accuracy in bacterial division while demonstrating the general applicability of PSICIC as a computational approach for quantitative, high-throughput analysis of cellular images.

  2. Gigavision - A weatherproof, multibillion pixel resolution time-lapse camera system for recording and tracking phenology in every plant in a landscape

    Science.gov (United States)

    Brown, T.; Borevitz, J. O.; Zimmermann, C.

    2010-12-01

    We have a developed a camera system that can record hourly, gigapixel (multi-billion pixel) scale images of an ecosystem in a 360x90 degree panorama. The “Gigavision” camera system is solar-powered and can wirelessly stream data to a server. Quantitative data collection from multiyear timelapse gigapixel images is facilitated through an innovative web-based toolkit for recording time-series data on developmental stages (phenology) from any plant in the camera’s field of view. Gigapixel images enable time-series recording of entire landscapes with a resolution sufficient to record phenology from a majority of individuals in entire populations of plants. When coupled with next generation sequencing, quantitative population genomics can be performed in a landscape context linking ecology and evolution in situ and in real time. The Gigavision camera system achieves gigapixel image resolution by recording rows and columns of overlapping megapixel images. These images are stitched together into a single gigapixel resolution image using commercially available panorama software. Hardware consists of a 5-18 megapixel resolution DSLR or Network IP camera mounted on a pair of heavy-duty servo motors that provide pan-tilt capabilities. The servos and camera are controlled with a low-power Windows PC. Servo movement, power switching, and system status monitoring are enabled with Phidgets-brand sensor boards. System temperature, humidity, power usage, and battery voltage are all monitored at 5 minute intervals. All sensor data is uploaded via cellular or 802.11 wireless to an interactive online interface for easy remote monitoring of system status. Systems with direct internet connections upload the full sized images directly to our automated stitching server where they are stitched and available online for viewing within an hour of capture. Systems with cellular wireless upload an 80 megapixel “thumbnail” of each larger panorama and full-sized images are manually

  3. A novel gamma-ray detector with submillimeter resolutions using a monolithic MPPC array with pixelized Ce:LYSO and Ce:GGAG crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kato, T., E-mail: katou.frme.8180@asagi.waseda.jp [Research Institute for Science and Engineering, Waseda University, 3-4-1, Ohkubo, Shinjuku, Tokyo (Japan); Kataoka, J.; Nakamori, T.; Miura, T.; Matsuda, H.; Kishimoto, A. [Research Institute for Science and Engineering, Waseda University, 3-4-1, Ohkubo, Shinjuku, Tokyo (Japan); Sato, K.; Ishikawa, Y.; Yamamura, K.; Nakamura, S.; Kawabata, N. [Solid State Division, Hamamatsu Photonics K. K., 1126-1, Ichino-cho, Hamamatsu, Shizuoka (Japan); Ikeda, H. [ISAS/JAXA, 3-1-1, Yoshinodai, Chuo-ku, Sagamihara-shi, Kanagawa (Japan); Yamamoto, S. [Kobe City College of Technology, 8-3, Gakuenhigashimati, Nishi-ku, Kobe-shi, Hyougo 651-2194 (Japan); Kamada, K. [Materials Research Laboratory, Furukawa Co., Ltd., 1-25-13, Kannondai, Tsukuba, Ibaraki 305-0856 (Japan)

    2013-01-21

    We have developed a large-area monolithic Multi-Pixel Photon Counter (MPPC) array consisting of 4×4 channels with a three-side buttable package. Each channel has a photosensitive area of 3×3 mm{sup 2} and 3600 Geiger mode avalanche photodiodes (APDs). For typical operational gain of 7.5×10{sup 5} at +20 °C, gain fluctuation over the entire MPPC device is only ±5.6%, and dark count rates (as measured at the 1 p.e. level) amount to ≤400kcps per channel. We first fabricated a gamma-ray camera consisting of the MPPC array with one-to-one coupling to a Ce-doped (Lu,Y){sub 2}(SiO{sub 4})O (Ce:LYSO) crystal array (4×4 array of 3×3×10 mm{sup 3} crystals). Energy and time resolutions of 11.5±0.5% (FWHM at 662 keV) and 493±22ps were obtained, respectively. When using the charge division resistor network, which compiles signals into four position-encoded analog outputs, the ultimate positional resolution is estimated as 0.19 mm in both X and Y directions, while energy resolution of 10.2±0.4% (FWHM) was obtained. Finally, we fabricated submillimeter Ce:LYSO and Ce-doped Gd{sub 3}Ga{sub 3}Al{sub 2}O{sub 12} (Ce:GGAG) scintillator matrices each consisting of 1.0×1.0, 0.7×0.7 and 0.5×0.5 mm{sup 2} pixels, to further improve the spatial resolution. In all types of Ce:LYSO and Ce:GGAG matrices, each crystal was clearly resolved in the position histograms when irradiated by a {sup 137}Cs source. The energy resolutions for 662 keV gamma-rays for each Ce:LYSO and Ce:GGAG scintillator matrix were ≤14.3%. These results suggest excellent potential for its use as a high spatial medical imaging device, particularly in positron emission tomography (PET). -- Highlights: ► We developed a newly designed large-area monolithic MPPC array. ► We obtained fine gain uniformity, and good energy and time resolutions when coupled to the LYSO scintillator. ► We fabricated gamma-ray camera consisting of the MPPC array and submillimeter pixelized LYSO and GGAG scintillators. ► In

  4. Hybrid Constraints of Pure and Mixed Pixels for Soft-Then-Hard Super-Resolution Mapping with Multiple Shifted Images

    NARCIS (Netherlands)

    Chen, Yuehong; Ge, Yong; Heuvelink, G.B.M.; Hu, Jianlong; Jiang, Yu

    2015-01-01

    Multiple shifted images (MSIs) have been widely applied to many super-resolution mapping (SRM) approaches to improve the accuracy of fine-scale land-cover maps. Most SRM methods with MSIs involve two processes: subpixel sharpening and class allocation. Complementary information from the MSIs has

  5. Hybrid Constraints of Pure and Mixed Pixels for Soft-Then-Hard Super-Resolution Mapping with Multiple Shifted Images

    NARCIS (Netherlands)

    Chen, Yuehong; Ge, Yong; Heuvelink, G.B.M.; Hu, Jianlong; Jiang, Yu

    2015-01-01

    Multiple shifted images (MSIs) have been widely applied to many super-resolution mapping (SRM) approaches to improve the accuracy of fine-scale land-cover maps. Most SRM methods with MSIs involve two processes: subpixel sharpening and class allocation. Complementary information from the MSIs has

  6. A novel gamma-ray detector with submillimeter resolutions using a monolithic MPPC array with pixelized Ce:LYSO and Ce:GGAG crystals

    Science.gov (United States)

    Kato, T.; Kataoka, J.; Nakamori, T.; Miura, T.; Matsuda, H.; Kishimoto, A.; Sato, K.; Ishikawa, Y.; Yamamura, K.; Nakamura, S.; Kawabata, N.; Ikeda, H.; Yamamoto, S.; Kamada, K.

    2013-01-01

    We have developed a large-area monolithic Multi-Pixel Photon Counter (MPPC) array consisting of 4×4 channels with a three-side buttable package. Each channel has a photosensitive area of 3×3 mm2 and 3600 Geiger mode avalanche photodiodes (APDs). For typical operational gain of 7.5×105 at +20 °C, gain fluctuation over the entire MPPC device is only ±5.6%, and dark count rates (as measured at the 1 p.e. level) amount to ≤400 kcps per channel. We first fabricated a gamma-ray camera consisting of the MPPC array with one-to-one coupling to a Ce-doped (Lu, Y)2(SiO4)O (Ce:LYSO) crystal array (4×4 array of 3×3×10 mm3 crystals). Energy and time resolutions of 11.5±0.5% (FWHM at 662 keV) and 493±22 ps were obtained, respectively. When using the charge division resistor network, which compiles signals into four position-encoded analog outputs, the ultimate positional resolution is estimated as 0.19 mm in both X and Y directions, while energy resolution of 10.2±0.4% (FWHM) was obtained. Finally, we fabricated submillimeter Ce:LYSO and Ce-doped Gd3Ga3Al2O12 (Ce:GGAG) scintillator matrices each consisting of 1.0×1.0, 0.7×0.7 and 0.5×0.5 mm2 pixels, to further improve the spatial resolution. In all types of Ce:LYSO and Ce:GGAG matrices, each crystal was clearly resolved in the position histograms when irradiated by a 137Cs source. The energy resolutions for 662 keV gamma-rays for each Ce:LYSO and Ce:GGAG scintillator matrix were ≤14.3%. These results suggest excellent potential for its use as a high spatial medical imaging device, particularly in positron emission tomography (PET).

  7. Developing fine-pixel CdTe detectors for the next generation of high-resolution hard x-ray telescopes

    Science.gov (United States)

    Christe, Steven

    Over the past decade, the NASA Marshall Space Flight Center (MSFC) has been improving the angular resolution of hard X-ray (HXR; 20 "70 keV) optics to the point that we now routinely manufacture optics modules with an angular resolution of 20 arcsec Half Power Diameter (HDP), almost three times the performance of NuSTAR optics (Ramsey et al. 2013; Gubarev et al. 2013a; Atkins et al. 2013). New techniques are currently being developed to provide even higher angular resolution. High angular resolution HXR optics require detectors with a large number of fine pixels in order to adequately sample the telescope point spread function (PSF) over the entire field of view. Excessively over-sampling the PSF will increase readout noise and require more processing with no appreciable increase in image quality. An appropriate level of over-sampling is to have 3 pixels within the HPD. For the HERO mirrors, where the HPD is 26 arcsec over a 6-m focal length converts to 750 μm, the optimum pixel size is around 250 μm. At a 10-m focal length these detectors can support a 16 arcsec HPD. Of course, the detectors must also have high efficiency in the HXR region, good energy resolution, low background, low power requirements, and low sensitivity to radiation damage (Ramsey 2001). The ability to handle high counting rates is also desirable for efficient calibration. A collaboration between Goddard Space Flight Center (GSFC), MSFC, and Rutherford Appleton Laboratory (RAL) in the UK is developing precisely such detectors under an ongoing, funded APRA program (FY2015 to FY2017). The detectors use the RALdeveloped Application Specific Integrated Circuit (ASIC) dubbed HEXITEC, for High Energy X-Ray Imaging Technology. These HEXITEC ASICs can be bonded to 1- or 2- mm-thick Cadmium Telluride (CdTe) or Cadmium-Zinc-Telluride (CZT) to create a fine (250 μm pitch) HXR detector (Jones et al. 2009; Seller et al. 2011). The objectives of this funded effort are to develop and test a HEXITEC

  8. Characterization of Pixel Sensors

    CERN Document Server

    Oliveira, Felipe Ferraz

    2017-01-01

    It was commissioned at CERN ATLAS pixel group a fluorescence setup for characterization of pixel sensors. The idea is to measure the energies of different targets to calibrate your sensor. It was measured four matrices (80, 95, 98 and 106) of the Investigator1 sensor with different deep PW using copper, iron and titanium as target materials. The matrix 80 has a higher gain (0.065 ± 0.002) and matrix 106 has a better energy resolution (0.05 ± 0.04). The noise of the setup is around 3.6 mV .

  9. Ground-roll noise extraction and suppression using high-resolution linear Radon transform

    Science.gov (United States)

    Hu, Yue; Wang, Limin; Cheng, Feng; Luo, Yinhe; Shen, Chao; Mi, Binbin

    2016-05-01

    Ground-roll is a main type of strong noises in petroleum seismic exploration. Suppression of this kind of noise is essential to improve the signal-to-noise ratio of seismic data. In the time-offset (t-x) domain, the ground-roll noise and the effective waves (e.g., direct waves, reflections) overlap with each other in terms of time and frequency, which make it difficult to suppress ground roll noise in exploration seismic data. However, significant different features shown in the frequency-velocity (f-v) domain make it possible to separate ground roll noise and effective waves effectively. We propose a novel method to separate them using high-resolution linear Radon transform (LRT). Amplitude and phase information is preserved during the proposed quasi-reversible transformation. The reversibility and linearity of LRT provide a foundation for ground-roll noise suppression in the f-v domain. We extract the energy of ground-roll noise in the f-v domain, and transform the extracted part back to the t-x domain to obtain the ground-roll noise shot gather. Finally, the extracted ground-roll noise is subtracted from the original data arithmetically. Theoretical tests and a real world example have been implemented to illustrate that the ground-roll noise suppression can be achieved with negligible distortion of the effective signals. When compared with the adaptive ground-roll attenuation method and the K-L transform method, the real world example shows the superiority of our method in suppressing the ground-roll noise and preserving the amplitude and phase information of effective waves.

  10. Effect of Pixel's Spatial Characteristics on Recognition of Isolated Pixelized Chinese Character.

    Science.gov (United States)

    Yang, Kun; Liu, Shuang; Wang, Hong; Liu, Wei; Wu, Yaowei

    2015-01-01

    The influence of pixel's spatial characteristics on recognition of isolated Chinese character was investigated using simulated prosthestic vision. The accuracy of Chinese character recognition with 4 kinds of pixel number (6*6, 8*8, 10*10, and 12*12 pixel array) and 3 kinds of pixel shape (Square, Dot and Gaussian) and different pixel spacing were tested through head-mounted display (HMD). A captured image of Chinese characters in font style of Hei were pixelized with Square, Dot and Gaussian pixel. Results showed that pixel number was the most important factor which could affect the recognition of isolated pixelized Chinese Chartars and the accuracy of recognition increased with the addition of pixel number. 10*10 pixel array could provide enough information for people to recognize an isolated Chinese character. At low resolution (6*6 and 8*8 pixel array), there were little difference of recognition accuracy between different pixel shape and different pixel spacing. While as for high resolution (10*10 and 12*12 pixel array), the fluctuation of pixel shape and pixel spacing could not affect the performance of recognition of isolated pixelized Chinese Character.

  11. Processing of A New Digital Orthoimage Map of The Martian Western Hemisphere Using Data Obtained From The Mars Orbiter Camera At A Resolution of 256 Pixel/deg

    Science.gov (United States)

    Wählisch, M.; Niedermaier, G.; van Gasselt, S.; Scholten, F.; Wewel, F.; Roatsch, T.; Matz, K.-D.; Jaumann, R.

    We present a new digital orthoimage map of Mars using data obtained from the CCD line scanner Mars Orbiter Camera (MOC) of the Mars Global Surveyor Mis- sion (MGS) [1,2]. The map covers the Mars surface from 0 to 180 West and from 60 South to 60 North with the MDIM2 resolution of 256 pixel/degree and size. Image data processing has been performed using multiple programs, developed by DLR, Technical University of Berlin [3], JPL, and the USGS. 4,339 Context and 183 Geodesy images [2] were included. After radiometric corrections, the images were Mars referenced [4], geometrically corrected [5] and orthoprojected using a global Martian Digital Terrain Model (DTM) with a resolution of 64 pixel/degree, developed at DLR and based on MGS Mars Orbiter Laser Altimeter (MOLA) data [6]. To elim- inate major differences in brightness between the individual images of the mosaics, high- and low-pass filter processing techniques were applied for each image. After filtering, the images were mosaicked without registering or using block adjustment techniques in order to improve the geometric quality. It turns out that the accuracy of the navigation data has such a good quality that the orthoimages fit very well to each other. When merging the MOC mosaic with the MOLA data using IHS- trans- formation, we recognized very good correspondence between these two datasets. We create a topographic image map of the Coprates region (MC­18) adding contour lines derived from the global DTM to the mosaic. These maps are used for geological and morphological interpretations in order to review and improve our current Viking-based knowledge about the Martian surface. References: [1] www.mssss.com, [2] Caplinger, M. and M. Malin, "The Mars Or- biter Camera Geodesy Campaign, JGR, in press, [3] Scholten, F., Vol XXXI, Part B2, Wien 1996, p.351-356, [4] naïf.jpl.nasa.gov, [5] R.L.Kirk. et al. (2001), "Geometric Calibration of the Mars Orbiter Cameras and Coalignment with Mars Orbiter Laser Altimeter

  12. Ozone vertical distribution retrieval from ground-based high resolution infrared solar spectra

    Science.gov (United States)

    Pougatchev, N. S.; Connor, B. J.; Rinsland, C. P.

    1995-01-01

    A practical procedure for the retrieval of ozone vertical profiles from ground-based high resolution Fourier transform infrared solar spectra has been developed. The analysis is based on a multilayer line-by-line forward model and a semi-empirical version of the optimal estimation inversion method of Rodgers. The 1002.6-1003.2 cm(exp -1) spectral interval has been selected for the analysis on the basis of synthetic spectrum calculations. This interval contains numerous ozone lines covering a range of intensities and providing retrieval sensitivity from ground level to about 35 km. Characterization of the method and an error analysis have been performed. For a spectral resolution of 0.05-0.01 cm(exp -1) and a signal-to-noise ratio greater than or equal to 100 the retrieval is stable with a vertical resolution of approximately 5 km attainable near the surface degrading to approximately 10 km in the stratosphere. Synthetic spectra studies show that the a priori profile and weak constraints selected for the retrievals introduce no significant biases for a wide range of ozone profiles.

  13. Pixelated neutron image plates

    Science.gov (United States)

    Schlapp, M.; Conrad, H.; von Seggern, H.

    2004-09-01

    Neutron image plates (NIPs) have found widespread application as neutron detectors for single-crystal and powder diffraction, small-angle scattering and tomography. After neutron exposure, the image plate can be read out by scanning with a laser. Commercially available NIPs consist of a powder mixture of BaFBr : Eu2+ and Gd2O3 dispersed in a polymer matrix and supported by a flexible polymer sheet. Since BaFBr : Eu2+ is an excellent x-ray storage phosphor, these NIPs are particularly sensitive to ggr-radiation, which is always present as a background radiation in neutron experiments. In this work we present results on NIPs consisting of KCl : Eu2+ and LiF that were fabricated into ceramic image plates in which the alkali halides act as a self-supporting matrix without the necessity for using a polymeric binder. An advantage of this type of NIP is the significantly reduced ggr-sensitivity. However, the much lower neutron absorption cross section of LiF compared with Gd2O3 demands a thicker image plate for obtaining comparable neutron absorption. The greater thickness of the NIP inevitably leads to a loss in spatial resolution of the image plate. However, this reduction in resolution can be restricted by a novel image plate concept in which a ceramic structure with square cells (referred to as a 'honeycomb') is embedded in the NIP, resulting in a pixelated image plate. In such a NIP the read-out light is confined to the particular illuminated pixel, decoupling the spatial resolution from the optical properties of the image plate material and morphology. In this work, a comparison of experimentally determined and simulated spatial resolutions of pixelated and unstructured image plates for a fixed read-out laser intensity is presented, as well as simulations of the properties of these NIPs at higher laser powers.

  14. High-Resolution Imaging in the Visible on Large Ground-Based Telescopes

    CERN Document Server

    Mackay, Craig; Crass, Jonathan; King, David L; Labadie, Lucas; González-Escélera, Víctor; Puga, Marta; Pérez-Garrido, Antonio; López, Roberto; Oscoz, Alejandro; Pérez-Prieto, Jorge A; Rodríguez-Ramos, Luis F; Velasco, Sergio; Villó, Isidro

    2014-01-01

    Lucky Imaging combined with a low order adaptive optics system has given the highest resolution images ever taken in the visible or near infrared of faint astronomical objects. This paper describes a new instrument that has already been deployed on the WHT 4.2m telescope on La Palma, with particular emphasis on the optical design and the predicted system performance. A new design of low order wavefront sensor using photon counting CCD detectors and multi-plane curvature wavefront sensor will allow virtually full sky coverage with faint natural guide stars. With a 2 x 2 array of 1024 x 1024 photon counting EMCCDs, AOLI is the first of the new class of high sensitivity, near diffraction limited imaging systems giving higher resolution in the visible from the ground than hitherto been possible from space.

  15. High Resolution Imaging of Satellites with Ground-Based 10-m Astronomical Telescopes

    Energy Technology Data Exchange (ETDEWEB)

    Marois, C

    2007-01-04

    High resolution imaging of artificial satellites can play an important role in current and future space endeavors. One such use is acquiring detailed images that can be used to identify or confirm damage and aid repair plans. It is shown that a 10-m astronomical telescope equipped with an adaptive optics system (AO) to correct for atmospheric turbulence using a natural guide star can acquire high resolution images of satellites in low-orbits using a fast shutter and a near-infrared camera even if the telescope is not capable of tracking satellites. With the telescope pointing towards the satellite projected orbit and less than 30 arcsec away from a guide star, multiple images of the satellite are acquired on the detector using the fast shutter. Images can then be shifted and coadded by post processing to increase the satellite signal to noise ratio. Using the Keck telescope typical Strehl ratio and anisoplanatism angle as well as a simple diffusion/reflection model for a satellite 400 km away observed near Zenith at sunset or sunrise, it is expected that such system will produced > 10{sigma} K-band images at a resolution of 10 cm inside a 60 arcsec diameter field of view. If implemented, such camera could deliver the highest resolution satellite images ever acquired from the ground.

  16. High Resolution Imaging of Satellites with Ground-Based 10-m Astronomical Telescopes

    Energy Technology Data Exchange (ETDEWEB)

    Marois, C

    2007-01-04

    High resolution imaging of artificial satellites can play an important role in current and future space endeavors. One such use is acquiring detailed images that can be used to identify or confirm damage and aid repair plans. It is shown that a 10-m astronomical telescope equipped with an adaptive optics system (AO) to correct for atmospheric turbulence using a natural guide star can acquire high resolution images of satellites in low-orbits using a fast shutter and a near-infrared camera even if the telescope is not capable of tracking satellites. With the telescope pointing towards the satellite projected orbit and less than 30 arcsec away from a guide star, multiple images of the satellite are acquired on the detector using the fast shutter. Images can then be shifted and coadded by post processing to increase the satellite signal to noise ratio. Using the Keck telescope typical Strehl ratio and anisoplanatism angle as well as a simple diffusion/reflection model for a satellite 400 km away observed near Zenith at sunset or sunrise, it is expected that such system will produced > 10{sigma} K-band images at a resolution of 10 cm inside a 60 arcsec diameter field of view. If implemented, such camera could deliver the highest resolution satellite images ever acquired from the ground.

  17. High Resolution Spectral Analysis of Hiss and Chorus Emissions in Ground Based Data

    Science.gov (United States)

    Hosseini Aliabad, S. P.; Golkowski, M.; Gibby, A. R.

    2015-12-01

    The dynamic evolution of the radiation belts is believed to be controlled in large part by two separate but related classes of naturally occurring plasma waves: ELF/VLF chorus and hiss emissions. Although whistler mode chorus has been extensively studied since the first reports by Storey in 1953, the source mechanism and properties are still subjects of active research. Moreover, the origin of plasmaspheric hiss, the electromagnetic emission believed to be responsible for the gap between the inner and outer radiation belts, has been debated for over four decades. Although these waves can be observed in situ on spacecraft, ground-based observing stations can provide orders of magnitude higher data volumes and decades long data coverage essential for certain long-term and statistical studies of wave properties. Recent observational and theoretical works suggest that high resolution analysis of the spectral features of both hiss and chorus emissions can provide insight into generation processes and be used to validate existing theories. Application of the classic Fourier (FFT) technique unfortunately yields a tradeoff between time and frequency resolution. In additional to Fourier spectra, we employ novel methods to make spectrograms with high time and frequency resolutions, independently using minimum variance distortionless response (MVDR). These techniques are applied to ground based data observations of hiss and chorus made in Alaska. Plasmaspheric hiss has been widely regarded as a broadband, structure less, incoherent emission. We quantify the extent to which plasmaspheric hiss can be a coherent emission with complex fine structure. Likewise, to date, researchers have differentiated between hiss and chorus coherency primarily using qualitative "naked eye" approaches to amplitude spectra. Using a quantitative approach to observed amplitude and we present more rigorous classification criteria for these emissions.

  18. Reducing Earth Topography Resolution for SMAP Mission Ground Tracks Using K-Means Clustering

    Science.gov (United States)

    Rizvi, Farheen

    2013-01-01

    The K-means clustering algorithm is used to reduce Earth topography resolution for the SMAP mission ground tracks. As SMAP propagates in orbit, knowledge of the radar antenna footprints on Earth is required for the antenna misalignment calibration. Each antenna footprint contains a latitude and longitude location pair on the Earth surface. There are 400 pairs in one data set for the calibration model. It is computationally expensive to calculate corresponding Earth elevation for these data pairs. Thus, the antenna footprint resolution is reduced. Similar topographical data pairs are grouped together with the K-means clustering algorithm. The resolution is reduced to the mean of each topographical cluster called the cluster centroid. The corresponding Earth elevation for each cluster centroid is assigned to the entire group. Results show that 400 data points are reduced to 60 while still maintaining algorithm performance and computational efficiency. In this work, sensitivity analysis is also performed to show a trade-off between algorithm performance versus computational efficiency as the number of cluster centroids and algorithm iterations are increased.

  19. High-resolution geophysical profiling using a stepped-frequency ground penetrating radar

    Energy Technology Data Exchange (ETDEWEB)

    Noon, D.; Longstaff, D. [The University of Queensland, (Australia)

    1996-05-01

    This paper describes the results of a ground penetrating radar (GPR) system which uses stepped-frequency waveforms to obtain high-resolution geophysical profiles. The main application for this system is the high-resolution mapping of thin coal seam structures, in order to assist surface mining operations in open-cut coal mines. The required depth of penetration is one meter which represents the maximum thickness of coal seams that are designated `thin`. A resolution of five centimeters is required to resolve the minimum thickness of coal (or shale partings) which can be economically recovered in an open-cut coal mine. For this application, a stepped-frequency GPR system has been developed, because of its ultrawide bandwidth (1 to 2 GHz) and high external loop sensitivity (155 dB). The field test results of the stepped-frequency GPR system on a concrete pavement and at two Australian open-cut coal mines are also presented. 7 refs., 5 figs.

  20. 积雪混合像元光谱特征观测及解混方法比较%Observations of Snow Mixed Pixel Spectral Characteristics Using a Ground-Based Spectral Radiometer and Comparing with Unmixing Algorithms

    Institute of Scientific and Technical Information of China (English)

    郝晓华; 王杰; 王建; 黄晓东; 李弘毅; 刘艳

    2012-01-01

    The unmixing algorithms of mixed snow pixels and the fractional snow cover products are an important research direc-tion for snow remote sensing. In the present study, we first designed the mixed snow pixels of different snow fraction/proportion in Northern Xinjiang, China as ground truth. Then, a SVC HR-1024 ground-based spectral radiometer was used for measuring the spectral property of this designed pixel for different snow fractions and different underlying surfaces. Finally, using the measured spectral data, the four mixed-pixel decomposition models were validated and evaluated for their performance in terms of accuracy and computational efficiency. The results showed that the reflectivity does not decline linearly with the reduction of snow ratio in the pixel, and that the unmixing accuracy inversely depends on the scales of the observation. Further, the comparison of the above mentioned unmixing algotihms showed that the linear regression method has the worst accuracy, especially when the snow proportion is less than 50%; the accuracy of sparse regression algorithm and non-negative matrix factorization were slightly higher than the full constrained linear mixed-pixel decomposition; however, full constrained linear mixed-pixel decomposition method had higher computational efficiency than the other two methods; the sparse regression algorithm has lowest computational efficiency. With unmixing remote sensing images, due to the large data volumes, we must consider the algorithms' computational efficiency. This study would promote quantitative researches on snow mixed pixel decomposition, and provide a theoretical basis for accurately extracting the snow coverage of interest area using remote sensing images.%积雪混合像元分解方法研究及积雪比例产品的发展是积雪遥感的重要研究方向.在我国北疆地区利用SVC HR-1024野外便携式光谱仪观测了已知积雪比例的混合像元光谱特征并进行系统分析,同时,采用四

  1. The high-resolution extraterrestrial solar spectrum (QASUMEFTS determined from ground-based solar irradiance measurements

    Directory of Open Access Journals (Sweden)

    J. Gröbner

    2017-09-01

    Full Text Available A high-resolution extraterrestrial solar spectrum has been determined from ground-based measurements of direct solar spectral irradiance (SSI over the wavelength range from 300 to 500 nm using the Langley-plot technique. The measurements were obtained at the Izaña Atmospheric Research Centre from the Agencia Estatal de Meteorología, Tenerife, Spain, during the period 12 to 24 September 2016. This solar spectrum (QASUMEFTS was combined from medium-resolution (bandpass of 0.86 nm measurements of the QASUME (Quality Assurance of Spectral Ultraviolet Measurements in Europe spectroradiometer in the wavelength range from 300 to 500 nm and high-resolution measurements (0.025 nm from a Fourier transform spectroradiometer (FTS over the wavelength range from 305 to 380 nm. The Kitt Peak solar flux atlas was used to extend this high-resolution solar spectrum to 500 nm. The expanded uncertainties of this solar spectrum are 2 % between 310 and 500 nm and 4 % at 300 nm. The comparison of this solar spectrum with solar spectra measured in space (top of the atmosphere gave very good agreements in some cases, while in some other cases discrepancies of up to 5 % were observed. The QASUMEFTS solar spectrum represents a benchmark dataset with uncertainties lower than anything previously published. The metrological traceability of the measurements to the International System of Units (SI is assured by an unbroken chain of calibrations leading to the primary spectral irradiance standard of the Physikalisch-Technische Bundesanstalt in Germany.

  2. Tomographic airborne ground penetrating radar imaging: Achievable spatial resolution and on-field assessment

    Science.gov (United States)

    Catapano, Ilaria; Crocco, Lorenzo; Krellmann, Yvonne; Triltzsch, Gunnar; Soldovieri, Francesco

    2014-06-01

    Ground Penetrating Radar (GPR) airborne systems are gaining an increasing attention as effective monitoring tools capable of underground investigation of wide areas. With respect to this frame, the paper deals with a reconstruction approach specifically designed to image buried targets from airborne gathered scattered field data. The role of the measurement configuration is investigated in order to address the practical problem of how multi-monostatic and multi-frequency data should be gathered, in terms of synthetic aperture length and frequency range, and how the available data affect the achievable reconstruction capabilities. Such an analysis allows us to evaluate the performance of the reconstruction approach in terms of transversal and depth resolution limits. Finally, an experimental validation of the approach is performed by processing real data.

  3. Development of SOI pixel detector in Cracow

    CERN Document Server

    Bugiel, Szymon; Glab, Sebastian; Idzik, Marek; Moron, Jakub; Kapusta, Piotr Julian; Kucewicz, Wojciech; Turala, Michal

    2015-01-01

    This paper presents the design of a new monolithic Silicon-On-Insulator pixel sensor in $200~nm$ SOI CMOS technology. The main application of the proposed pixel detector is the spectroscopy, but it can also be used for the minimum ionizing particle (MIP) tracking in particle physics experiments. For this reason few different versions of pixel cells are developed: a source-follower based pixel for tracking, a low noise pixel with preamplifier for spectroscopy, and a self-triggering pixel for time and amplitude measurements. In addition the design of a Successive Approximation Register Analog-to-Digital Converter (SAR ADC) is also presented. A 10-bit SAR ADC is developed for spectroscopic measurements and a lower resolution 6-bit SAR ADC is integrated in the pixel matrix as a column ADC, for tracking applications.

  4. Infrared single-pixel imaging utilising microscanning

    CERN Document Server

    Sun, Ming-Jie; Phillips, David B; Gibson, Graham M; Padgett, Miles J

    2015-01-01

    Since the invention of digital cameras there has been a concerted drive towards detector arrays with higher spatial resolution. Microscanning is a technique that provides a final higher resolution image by combining multiple images of a lower resolution. Each of these low resolution images is subject to a sub-pixel sized lateral displacement. In this work we apply the microscanning approach to an infrared single-pixel camera. For the same final resolution and measurement resource, we show that microscanning improves the signal-to-noise ratio (SNR) of reconstructed images by approximately 50%. In addition, this strategy also provides access to a stream of low-resolution 'preview' images throughout each high-resolution acquisition. Our work demonstrates an additional degree of flexibility in the trade-off between SNR and spatial resolution in single-pixel imaging techniques.

  5. People and pixels in the Sahel: a study linking coarse-resolution remote sensing observations to land users' perceptions of their changing environment in Senegal

    Directory of Open Access Journals (Sweden)

    Stefanie M. Herrmann

    2014-09-01

    Full Text Available Mounting evidence from satellite observations of a re-greening across much of the Sahel and Sudan zones over the past three decades has raised questions about the extent and reversibility of desertification. Historical ground data that could help in interpreting the re-greening are scarce. To fill that void, we tapped into the collective memories of local land users from central and western Senegal in 39 focus groups and assessed the spatial association between their perceptions of vegetation changes over time and remote sensing-derived trends. To provide context to the vegetation changes, we also explored the land users' perspective on the evolution of other environmental and human variables that are potentially related to the greening, using participatory research methods. While increases in vegetation were confirmed by the study participants for certain areas, which spatially corresponded to satellite-observed re-greening, vegetation degradation dominated their perceptions of change. This degradation, although spatially extensive according to land users, flies under the radar of coarse-resolution remote sensing data because it is not necessarily associated with a decrease in biomass but rather with undesired changes in species composition. Few significant differences were found in the perceived trends of population pressure, environmental, and livelihood variables between communities that have greened up according to satellite data and those that have not. Our findings challenge the prevailing chain of assumptions of the satellite-observed greening trend indicating an improvement of environmental conditions in the sense of a rehabilitation of the vegetation cover after the great droughts of the 1970s and 1980s, and the improvement of environmental conditions possibly translating into more stable livelihoods and greater well-being of the populations. For monitoring desertification and rehabilitation, there is a need to develop remote sensing

  6. Geographic information system for fusion and analysis of high-resolution remote sensing and ground data

    Science.gov (United States)

    Freeman, Anthony; Way, Jo Bea; Dubois, Pascale; Leberl, Franz

    1993-01-01

    We seek to combine high-resolution remotely sensed data with models and ground truth measurements, in the context of a Geographical Information System (GIS), integrated with specialized image processing software. We will use this integrated system to analyze the data from two Case Studies, one at a boreal forest site, the other a tropical forest site. We will assess the information content of the different components of the data, determine the optimum data combinations to study biogeophysical changes in the forest, assess the best way to visualize the results, and validate the models for the forest response to different radar wavelengths/polarizations. During the 1990's, unprecedented amounts of high-resolution images from space of the Earth's surface will become available to the applications scientist from the LANDSAT/TM series, European and Japanese ERS-1 satellites, RADARSAT and SIR-C missions. When the Earth Observation Systems (EOS) program is operational, the amount of data available for a particular site can only increase. The interdisciplinary scientist, seeking to use data from various sensors to study his site of interest, may be faced with massive difficulties in manipulating such large data sets, assessing their information content, determining the optimum combinations of data to study a particular parameter, visualizing his results and validating his model of the surface. The techniques to deal with these problems are also needed to support the analysis of data from NASA's current program of Multi-sensor Airborne Campaigns, which will also generate large volumes of data. In the Case Studies outlined in this proposal, we will have somewhat unique data sets. For the Bonanza Creek Experimental Forest (Case 1) calibrated DC-8 SAR (Synthetic Aperture Radar) data and extensive ground truth measurement are already at our disposal. The data set shows documented evidence to temporal change. The Belize Forest Experiment (Case 2) will produce calibrated DC-8 SAR

  7. Geographic information system for fusion and analysis of high-resolution remote sensing and ground data

    Science.gov (United States)

    Freeman, Anthony; Way, Jo Bea; Dubois, Pascale; Leberl, Franz

    1993-01-01

    We seek to combine high-resolution remotely sensed data with models and ground truth measurements, in the context of a Geographical Information System (GIS), integrated with specialized image processing software. We will use this integrated system to analyze the data from two Case Studies, one at a boreal forest site, the other a tropical forest site. We will assess the information content of the different components of the data, determine the optimum data combinations to study biogeophysical changes in the forest, assess the best way to visualize the results, and validate the models for the forest response to different radar wavelengths/polarizations. During the 1990's, unprecedented amounts of high-resolution images from space of the Earth's surface will become available to the applications scientist from the LANDSAT/TM series, European and Japanese ERS-1 satellites, RADARSAT and SIR-C missions. When the Earth Observation Systems (EOS) program is operational, the amount of data available for a particular site can only increase. The interdisciplinary scientist, seeking to use data from various sensors to study his site of interest, may be faced with massive difficulties in manipulating such large data sets, assessing their information content, determining the optimum combinations of data to study a particular parameter, visualizing his results and validating his model of the surface. The techniques to deal with these problems are also needed to support the analysis of data from NASA's current program of Multi-sensor Airborne Campaigns, which will also generate large volumes of data. In the Case Studies outlined in this proposal, we will have somewhat unique data sets. For the Bonanza Creek Experimental Forest (Case 1) calibrated DC-8 SAR (Synthetic Aperture Radar) data and extensive ground truth measurement are already at our disposal. The data set shows documented evidence to temporal change. The Belize Forest Experiment (Case 2) will produce calibrated DC-8 SAR

  8. Sub-pixel mapping of water boundaries using pixel swapping algorithm (case study: Tagliamento River, Italy)

    Science.gov (United States)

    Niroumand-Jadidi, Milad; Vitti, Alfonso

    2015-10-01

    Taking the advantages of remotely sensed data for mapping and monitoring of water boundaries is of particular importance in many different management and conservation activities. Imagery data are classified using automatic techniques to produce maps entering the water bodies' analysis chain in several and different points. Very commonly, medium or coarse spatial resolution imagery is used in studies of large water bodies. Data of this kind is affected by the presence of mixed pixels leading to very outstanding problems, in particular when dealing with boundary pixels. A considerable amount of uncertainty inescapably occurs when conventional hard classifiers (e.g., maximum likelihood) are applied on mixed pixels. In this study, Linear Spectral Mixture Model (LSMM) is used to estimate the proportion of water in boundary pixels. Firstly by applying an unsupervised clustering, the water body is identified approximately and a buffer area considered ensuring the selection of entire boundary pixels. Then LSMM is applied on this buffer region to estimate the fractional maps. However, resultant output of LSMM does not provide a sub-pixel map corresponding to water abundances. To tackle with this problem, Pixel Swapping (PS) algorithm is used to allocate sub-pixels within mixed pixels in such a way to maximize the spatial proximity of sub-pixels and pixels in the neighborhood. The water area of two segments of Tagliamento River (Italy) are mapped in sub-pixel resolution (10m) using a 30m Landsat image. To evaluate the proficiency of the proposed approach for sub-pixel boundary mapping, the image is also classified using a conventional hard classifier. A high resolution image of the same area is also classified and used as a reference for accuracy assessment. According to the results, sub-pixel map shows in average about 8 percent higher overall accuracy than hard classification and fits very well in the boundaries with the reference map.

  9. Ground-based lidar and microwave radiometry synergy for high vertical resolution absolute humidity profiling

    Science.gov (United States)

    Barrera-Verdejo, María; Crewell, Susanne; Löhnert, Ulrich; Orlandi, Emiliano; Di Girolamo, Paolo

    2016-08-01

    Continuous monitoring of atmospheric humidity profiles is important for many applications, e.g., assessment of atmospheric stability and cloud formation. Nowadays there are a wide variety of ground-based sensors for atmospheric humidity profiling. Unfortunately there is no single instrument able to provide a measurement with complete vertical coverage, high vertical and temporal resolution and good performance under all weather conditions, simultaneously. For example, Raman lidar (RL) measurements can provide water vapor with a high vertical resolution, albeit with limited vertical coverage, due to sunlight contamination and the presence of clouds. Microwave radiometers (MWRs) receive water vapor information throughout the troposphere, though their vertical resolution is poor. In this work, we present an MWR and RL system synergy, which aims to overcome the specific sensor limitations. The retrieval algorithm combining these two instruments is an optimal estimation method (OEM), which allows for an uncertainty analysis of the retrieved profiles. The OEM combines measurements and a priori information, taking the uncertainty of both into account. The measurement vector consists of a set of MWR brightness temperatures and RL water vapor profiles. The method is applied to a 2-month field campaign around Jülich (Germany), focusing on clear sky periods. Different experiments are performed to analyze the improvements achieved via the synergy compared to the individual retrievals. When applying the combined retrieval, on average the theoretically determined absolute humidity uncertainty is reduced above the last usable lidar range by a factor of ˜ 2 with respect to the case where only RL measurements are used. The analysis in terms of degrees of freedom per signal reveal that most information is gained above the usable lidar range, especially important during daytime when the lidar vertical coverage is limited. The retrieved profiles are further evaluated using

  10. Serial Pixel Analog-to-Digital Converter

    Energy Technology Data Exchange (ETDEWEB)

    Larson, E D

    2010-02-01

    This method reduces the data path from the counter to the pixel register of the analog-to-digital converter (ADC) from as many as 10 bits to a single bit. The reduction in data path width is accomplished by using a coded serial data stream similar to a pseudo random number (PRN) generator. The resulting encoded pixel data is then decoded into a standard hexadecimal format before storage. The high-speed serial pixel ADC concept is based on the single-slope integrating pixel ADC architecture. Previous work has described a massively parallel pixel readout of a similar architecture. The serial ADC connection is similar to the state-of-the art method with the exception that the pixel ADC register is a shift register and the data path is a single bit. A state-of-the-art individual-pixel ADC uses a single-slope charge integration converter architecture with integral registers and “one-hot” counters. This implies that parallel data bits are routed among the counter and the individual on-chip pixel ADC registers. The data path bit-width to the pixel is therefore equivalent to the pixel ADC bit resolution.

  11. Autonomous Sub-Pixel Satellite Track Endpoint Determination for Space Based Images

    Energy Technology Data Exchange (ETDEWEB)

    Simms, L M

    2011-03-07

    An algorithm for determining satellite track endpoints with sub-pixel resolution in spaced-based images is presented. The algorithm allows for significant curvature in the imaged track due to rotation of the spacecraft capturing the image. The motivation behind the subpixel endpoint determination is first presented, followed by a description of the methodology used. Results from running the algorithm on real ground-based and simulated spaced-based images are shown to highlight its effectiveness.

  12. ATLAS IBL Pixel Upgrade

    CERN Document Server

    La Rosa, A

    2011-01-01

    The upgrade for ATLAS detector will undergo different phase towards super-LHC. The first upgrade for the Pixel detector will consist of the construction of a new pixel layer which will be installed during the first shutdown of the LHC machine (LHC phase-I upgrade). The new detector, called Insertable B-Layer (IBL), will be inserted between the existing pixel detector and a new (smaller radius) beam-pipe at a radius of 3.3 cm. The IBL will require the development of several new technologies to cope with increase of radiation or pixel occupancy and also to improve the physics performance which will be achieved by reducing the pixel size and of the material budget. Three different promising sensor technologies (planar-Si, 3D-Si and diamond) are currently under investigation for the pixel detector. An overview of the project with particular emphasis on pixel module is presented in this paper

  13. Evaluation of a Global Soil Moisture Product from Finer Spatial Resolution SAR Data and Ground Measurements at Irish Sites

    Directory of Open Access Journals (Sweden)

    Chiara Pratola

    2014-08-01

    Full Text Available In the framework of the European Space Agency Climate Change Initiative, a global, almost daily, soil moisture (SM product is being developed from passive and active satellite microwave sensors, at a coarse spatial resolution. This study contributes to its validation by using finer spatial resolution ASAR Wide Swath and in situ soil moisture data taken over three sites in Ireland, from 2007 to 2009. This is the first time a comparison has been carried out between three sets of independent observations from different sensors at very different spatial resolutions for such a long time series. Furthermore, the SM spatial distribution has been investigated at the ASAR scale within each Essential Climate Variable (ECV pixel, without adopting any particular model or using a densely distributed network of in situ stations. This approach facilitated an understanding of the extent to which geophysical factors, such as soil texture, terrain composition and altitude, affect the retrieved ECV SM product values in temperate grasslands. Temporal and spatial variability analysis provided high levels of correlation (p < 0.025 and low errors between the three datasets, leading to confidence in the new ECV SM global product, despite limitations in its ability to track the driest and wettest conditions.

  14. Detection of 3D tree root systems using high resolution ground penetration radar

    Science.gov (United States)

    Altdorff, D.; Honds, M.; Botschek, J.; Van Der Kruk, J.

    2014-12-01

    Knowledge of root systems and its distribution are important for biomass estimation as well as for the prevention of subsurface distribution network damages. Ground penetration radar (GPR) is a promising technique that enables a non-invasive imaging of tree roots. Due to the polarisation-dependent reflection coefficients and complicated three-dimensional root structure, accurate measurements with perpendicularly polarized antennas are needed. In this study, we show GPR data from two planes and one chestnut at two locations with different soil conditions. Perpendicular 10 x 10 cm grid measurements were made with a shielded 250 MHz antenna in combination with a high precision self-tracking laser theodolite that provides geo-referenced traces with a spatial resolution of ~ 2 cm. After selecting potential root hyperbolas within the perpendicular GPR profiles, the corresponding three-dimensional coordinates were extracted and visualized in planar view to reveal any linear structure that indicates a possible tree root. The coordinates of the selected linear structures were projected back to the surface by means of the laser-theodolite to indicate the locations for groundtruthing. Additionally, we interpolated the measured data into a 3D cube where time slices confirmed the locations of linear reflection events. We validated the indicated predictions by excavation of the soil with a suction dredge. Subsequent georeferencing of the true root distribution and comparison with the selected linear events showed that the approach was able to identify the precise position of roots with a diameter between 3 and 10 cm and a depth of up to 70 cm. However, not all linear events were roots; also mouse channels were found in these depths, since they also generate GPR hyperbolas aligned in linear structures. Roots at a second location at depths of 1 to 1.20 m did not generate identifiable hyperboles, which was probably due to an increased electrical conductivity below 86 cm depth. The

  15. Reading pixelized paragraphs of Chinese characters using simulated prosthetic vision.

    Science.gov (United States)

    Zhao, Ying; Lu, Yanyu; Zhao, Ji; Wang, Kaihu; Ren, Qiushi; Wu, Kaijie; Chai, Xinyu

    2011-07-29

    Visual prostheses offer a possibility of restoring useful reading ability to the blind. The psychophysics of simulating reading with a prosthesis using pixelized text has attracted attention recently. This study was an examination of the reading accuracy and efficiency of pixelized Chinese paragraphs after different parameters were altered. Forty native Chinese speakers with normal or corrected visual acuity (20/20) participated in four experiments. Reading accuracy and efficiency were measured after changing the character resolution, character size, pixel dropout percentage, number of gray levels, and luminance. A 5° × 5° character appeared to be the optimal size necessary for accurate pixelized reading. Reading accuracy close to 100% could be achieved with 10 × 10 pixels/character and ∼60% with a 6 × 6 pixel resolution. Pixel dropout adversely affected accuracy, and paragraphs with a 50% dropout were unreadable. Luminance had little effect; however, the number of gray levels significantly affected reading performance. Paragraph reading was at least 5% more accurate at each resolution than was the accuracy of Chinese character recognition. Character size and resolution, pixel dropout, and the number of gray levels clearly affected the reading performance of pixelized Chinese paragraphs. Compared with pixelized character recognition, pixelized Chinese paragraph reading achieved higher accuracy; thus, optimal Chinese reading performance may require prostheses with more electrodes (1000) than are required to read paragraphs in the Latin alphabet (500).

  16. Ibis ground calibration

    Energy Technology Data Exchange (ETDEWEB)

    Bird, A.J.; Barlow, E.J.; Tikkanen, T. [Southampton Univ., School of Physics and Astronomy (United Kingdom); Bazzano, A.; Del Santo, M.; Ubertini, P. [Istituto di Astrofisica Spaziale e Fisica Cosmica - IASF/CNR, Roma (Italy); Blondel, C.; Laurent, P.; Lebrun, F. [CEA Saclay - Sap, 91 - Gif sur Yvette (France); Di Cocco, G.; Malaguti, E. [Istituto di Astrofisica Spaziale e Fisica-Bologna - IASF/CNR (Italy); Gabriele, M.; La Rosa, G.; Segreto, A. [Istituto di Astrofisica Spaziale e Fisica- IASF/CNR, Palermo (Italy); Quadrini, E. [Istituto di Astrofisica Spaziale e Fisica-Cosmica, EASF/CNR, Milano (Italy); Volkmer, R. [Institut fur Astronomie und Astrophysik, Tubingen (Germany)

    2003-11-01

    We present an overview of results obtained from IBIS ground calibrations. The spectral and spatial characteristics of the detector planes and surrounding passive materials have been determined through a series of calibration campaigns. Measurements of pixel gain, energy resolution, detection uniformity, efficiency and imaging capability are presented. The key results obtained from the ground calibration have been: - optimization of the instrument tunable parameters, - determination of energy linearity for all detection modes, - determination of energy resolution as a function of energy through the range 20 keV - 3 MeV, - demonstration of imaging capability in each mode, - measurement of intrinsic detector non-uniformity and understanding of the effects of passive materials surrounding the detector plane, and - discovery (and closure) of various leakage paths through the passive shielding system.

  17. Pixel Vertex Detectors

    OpenAIRE

    Wermes, Norbert

    2006-01-01

    Pixel vertex detectors are THE instrument of choice for the tracking of charged particles close to the interaction point at the LHC. Hybrid pixel detectors, in which sensor and read-out IC are separate entities, constitute the present state of the art in detector technology. Three of the LHC detectors use vertex detectors based on this technology. A development period of almost 10 years has resulted in pixel detector modules which can stand the extreme rate and timing requirements as well as ...

  18. Pixelated CdZnTe drift detectors

    DEFF Research Database (Denmark)

    Kuvvetli, Irfan; Budtz-Jørgensen, Carl

    2005-01-01

    A technique, the so-called Drift Strip Method (DSM), for improving the CdZnTe detector energy response to hard X-rays and gamma-rays was applied as a pixel geometry. First tests have confirmed that this detector type provides excellent energy resolution and imaging performance. We specifically...... report on the performance of 3 mm thick prototype CZT drift pixel detectors fabricated using material from eV-products. We discuss issues associated with detector module performance. Characterization results obtained from several prototype drift pixel detectors are presented. Results of position...

  19. LISe pixel detector for neutron imaging

    Science.gov (United States)

    Herrera, Elan; Hamm, Daniel; Wiggins, Brenden; Milburn, Rob; Burger, Arnold; Bilheux, Hassina; Santodonato, Louis; Chvala, Ondrej; Stowe, Ashley; Lukosi, Eric

    2016-10-01

    Semiconducting lithium indium diselenide, 6LiInSe2 or LISe, has promising characteristics for neutron detection applications. The 95% isotopic enrichment of 6Li results in a highly efficient thermal neutron-sensitive material. In this study, we report on a proof-of-principle investigation of a semiconducting LISe pixel detector to demonstrate its potential as an efficient neutron imager. The LISe pixel detector had a 4×4 of pixels with a 550 μm pitch on a 5×5×0.56 mm3 LISe substrate. An experimentally verified spatial resolution of 300 μm was observed utilizing a super-sampling technique.

  20. Anode readout for pixellated CZT detectors

    Science.gov (United States)

    Narita, Tomohiko; Grindlay, Jonathan E.; Hong, Jaesub; Niestemski, Francis C.

    2004-02-01

    Determination of the photon interaction depth offers numerous advantages for an astronomical hard X-ray telescope. The interaction depth is typically derived from two signals: anode and cathode, or collecting and non-collecting electrodes. We present some preliminary results from our depth sensing detectors using only the anode pixel signals. By examining several anode pixel signals simultaneously, we find that we can estimate the interaction depth, and get sub-pixel 2-D position resolution. We discuss our findings and the requirements for future ASIC development.

  1. High resolution surface solar radiation patterns over Eastern Mediterranean: Satellite, ground-based, reanalysis data and radiative transfer simulations

    Science.gov (United States)

    Alexandri, G.; Georgoulias, A.; Meleti, C.; Balis, D.

    2013-12-01

    Surface solar radiation (SSR) and its long and short term variations play a critical role in the modification of climate and by extent of the social and financial life of humans. Thus, SSR measurements are of primary importance. SSR is measured for decades from ground-based stations for specific spots around the planet. During the last decades, satellite observations allowed for the assessment of the spatial variability of SSR at a global as well as regional scale. In this study, a detailed spatiotemporal view of the SSR over Eastern Mediterranean is presented at a high spatial resolution. Eastern Mediterranean is affected by various aerosol types (continental, sea, dust and biomass burning particles) and encloses countries with significant socioeconomical changes during the last decades. For the aims of this study, SSR data from satellites (Climate Monitoring Satellite Application Facility - CM SAF) and our ground station in Thessaloniki, a coastal city of ~1 million inhabitants in northern Greece, situated in the heart of Eastern Mediterranean (Eppley Precision pyranometer and Kipp & Zonen CM-11 pyranometer) are used in conjunction with radiative transfer simulations (Santa Barbara DISORT Atmospheric Radiative Transfer - SBDART). The CM SAF dataset used here includes monthly mean SSR observations at a high spatial resolution of 0.03x0.03 degrees for the period 1983-2005. Our ground-based SSR observations span from 1983 until today. SBDART radiative transfer simulations were implemented for a number of spots in the area of study in order to calculate the SSR. High resolution (level-2) aerosol and cloud data from MODIS TERRA and AQUA satellite sensors were used as input, as well as ground-based data from the AERONET. Data from other satellites (Earth Probe TOMS, OMI, etc) and reanalysis projects (ECMWF) were used where needed. The satellite observations, the ground-based measurements and the model estimates are validated against each other. The good agreement

  2. GravityCam: ground-based wide-field high-resolution imaging and high-speed photometry

    Science.gov (United States)

    Dominik, Martin; Mackay, Craig; Steele, Iain; Snodgrass, Colin; Hirsch, Michael; Gråe Jørgensen, Uffe; Hundertmark, Markus; Rebolo, Rafael; Horne, Keith; Bridle, Sarah; Sicardy, Bruno; Bramich, Daniel; Alsubai, Khalid

    2015-12-01

    The image blurring by the Earth's atmosphere generally poses a substantial limitation to ground-based observations. While opportunities in space are scarce, lucky imaging can correct over a much larger patch of sky and with much fainter reference stars. We propose the first of a new kind of versatile instruments, "GravityCam", composed of ~100 EMCCDs, that will open up two entirely new windows to ground-based astronomy: (1) wide-field high-resolution imaging, and (2) wide-field high-speed photometry. Potential applications include (a) a gravitational microlensing survey going 4 magnitudes deeper than current efforts, and thereby gaining a factor 100 in mass at the same sensitivity, which means probing down to Lunar mass or even below, (b) extra-solar planet hunting via transits in galactic bulge fields, with high time resolution well-suited for transit timing variation studies, (c) variable stars in crowded fields, with sensitivity to very short periods, (d) asteroseismology with many bright stars in one pointing, (e) serendipitous occultations of stars by small solar system bodies, giving access to the small end of the Kuiper Belt size distribution and potentially leading to the first detection of true Oort cloud objects, while predicted occultations at high time resolution can reveal atmospheres, satellites, or rings, (f) general data mining of the high-speed variable sky (down to 40 ms cadence).

  3. LIF LiDAR high resolution ground truth data, suitable to validate medium-resolution bands of MODIS/Terra radiometer in case of inner waterbody ecological monitoring

    Science.gov (United States)

    Pelevin, Vadim; Zavialov, Peter; Zlinszky, Andras; Khimchenko, Elizaveta; Toth, Viktor; Kremenetskiy, Vyacheslav

    2017-04-01

    The report is based on field measurements on the lake Balaton (Hungary) in September 2008 as obtained by Light Induced Fluorescence (LIF) portable LiDAR UFL-8. It was tested in natural lake waters and validated by contact conventional measurements. We had opportunity to compare our results with the MODIS/Terra spectroradiometer satellite images received at the satellite monitoring station of the Eötvös Loránd University (Budapest, Hungary) to make an attempt of lidar calibration of satellite medium-resolution bands data. Water quality parameters were surveyed with the help of UFL-8 in a time interval very close to the satellite overpass. High resolution maps of the chlorophyll-a, chromophoric dissolved organic matter and total suspended sediments spatial distributions were obtained. Our results show that the resolution provided by laboratory measurements on a few water samples does not resemble actual conditions in the lake, and it would be more efficient to measure these parameters less accurately but in a better spatial distribution with the LiDAR. The UFL instrument has a great potential for being used for collecting ground truth data for satellite remote sensing of these parameters. Its measurement accuracy is comparable to classic water sample measurements, the measurement speed is high and large areas can be surveyed in a time interval very close to the satellite overpass.

  4. High-resolution Fourier-transform infrared spectroscopy of the Coriolis coupled ground state and ν7 mode of ketenimine.

    Science.gov (United States)

    Bane, Michael K; Robertson, Evan G; Thompson, Christopher D; Medcraft, Chris; Appadoo, Dominique R T; McNaughton, Don

    2011-06-21

    High resolution FTIR spectra of the short lived species ketenimine have been recorded in the regions 390-1300 cm(-1) and 20-110 cm(-1) using synchrotron radiation. Two thousand six hundred sixty transitions of the ν(7) band centered at 693 cm(-1) and 126 far-IR rotational transitions have been assigned. Rotational and centrifugal distortion parameters for the ν(7) mode were determined and local Fermi and b-axis Coriolis interactions with 2ν(12) are treated. A further refinement of the ground state, ν(12) and ν(8) parameters was also achieved, including the treatment of previously unrecognized ac-axis and ab-axis second order perturbations to the ground state.

  5. Ultrahigh-resolution mapping of peatland microform using ground-based structure from motion with multiview stereo

    Science.gov (United States)

    Mercer, Jason J.; Westbrook, Cherie J.

    2016-11-01

    Microform is important in understanding wetland functions and processes. But collecting imagery of and mapping the physical structure of peatlands is often expensive and requires specialized equipment. We assessed the utility of coupling computer vision-based structure from motion with multiview stereo photogrammetry (SfM-MVS) and ground-based photos to map peatland topography. The SfM-MVS technique was tested on an alpine peatland in Banff National Park, Canada, and guidance was provided on minimizing errors. We found that coupling SfM-MVS with ground-based photos taken with a point and shoot camera is a viable and competitive technique for generating ultrahigh-resolution elevations (i.e., scientists' toolkit.

  6. A study in GUI aesthetics for modern pixel art games.

    OpenAIRE

    Grahn, Emma

    2013-01-01

    The clarity and usability of the graphical user interface is very important for the enjoyment of a digital game. Pixel art is an art style with low resolution consisting of a precise placing of pixels, the smallest unit of colour that a screen can display. Pixel art has the potential of being cheap, easy to make and nostalgic, but it takes some skill to handle. However the great weakness of pixel art is displaying letters, and small details with clarity. So is there a place for pixel art in m...

  7. It's all in the pixels: high resolution remote sensing data and the mapping and analysis of the archaeological and historical landscape

    Directory of Open Access Journals (Sweden)

    Erwin Meylemans

    2017-03-01

    Full Text Available In Flanders (Belgium a large amount of remote-sensing data has been acquired and processed over the past few years, including high-resolution lidar and multi/hyperspectral aerial photography. These new data are contributing to the detection of archaeological sites and the characterisation of the cultural/historical landscape. Of particular use in historically stable areas under forest and pasture, lidar demonstrates the presence of a large number of previously unknown features and sites. The analysis and modelling of these data, combined with other landscape data such as soil maps, augering data, geological and historical maps, and aerial photographs, also provide possible new instruments for the characterisation and evaluation of prehistoric and historic landscapes. This vast amount of new remote-sensing data, plus the information it delivers, however, presents not only obvious opportunities but also a number of challenges. A centralised online system was developed by the 'GIS-Flanders agency', storing both processed and raw data from multispectral recordings, airborne lidar, mobile mapping images etc., and presenting several download and visualisation possibilities and tools. A new system has also been set up to handle specific archaeological and cultural historical data (historical images and aerial photographs, archaeological field data. Dialogue is needed so that the preservation and management needs of the archaeological heritage are also included.

  8. The contribution of vegetation cover and bare soil to pixel reflectance in an arid ecosystem

    Science.gov (United States)

    Steele, C. M.; Smith, A.; Campanella, A.; Rango, A.

    2008-12-01

    The heterogeneity of vegetation and soils in arid and semi-arid environments complicates the analysis of medium spatial resolution remotely sensed imagery. A single pixel may contain several different types of vegetation, as well as a sizeable proportion of bare soil. We have used linear mixture modeling to explore the contribution of vegetation cover and bare soil to pixel reflectance. In October, 2006, aerial imagery (0.25 m spatial resolution) was acquired for our study sites in the Jornada Experimental Range, southern New Mexico. Imagery was also acquired from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) for June and November, 2006. These data corresponded with pre- and post monsoon conditions. Object-based feature extraction was used to classify the aerial imagery to shrub, grass and bare ground cover classes. Percent cover was then calculated for each cover class. Visible-near-infrared and shortwave infrared ASTER reflectance data from both dates were combined into a single 18-band dataset (30 m spatial resolution). A vector overlay from the classification results of the aerial imagery was used to define pure endmember pixels in the ASTER imagery. Estimates of the proportions of shrub, grass and bare ground cover from the linear mixture modeling approach were compared with cover calculated using feature extraction from the aerial imagery. The results indicate that reflectance in ASTER pixels is likely to be a linear combination of the cover proportions of the three main cover types (shrubs, grass, bare ground). However, noticeable outliers in the relationship between cover calculated from each method, indicate there may be other variables that affect the accuracy with which we can estimate cover using linear mixture modeling.

  9. Validation and understanding of Moderate Resolution Imaging Spectroradiometer aerosol products (C5) using ground-based measurements from the handheld Sun photometer network in China

    Science.gov (United States)

    Zhanqing Li; Feng Niu; Kwon-Ho Lee; Jinyuan Xin; Wei Min Hao; Bryce L. Nordgren; Yuesi Wang; Pucai Wang

    2007-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) currently provides the most extensive aerosol retrievals on a global basis, but validation is limited to a small number of ground stations. This study presents a comprehensive evaluation of Collection 4 and 5 MODIS aerosol products using ground measurements from the Chinese Sun Hazemeter Network (CSHNET). The...

  10. High-resolution mapping, modeling, and evolution of subsurface geomorphology using ground-penetrating radar techniques

    Digital Repository Service at National Institute of Oceanography (India)

    Loveson, V.J.; Gujar, A.R.

    data over an area under study. The gap between sample locations are to be either simulated or manipulated through various statistical methods. Under such conditions, mapping of the area may not yield the reality of the subsurface features in between... continuous profiles along with 200 MHz antenna and measuring wheel. Some times for confirmation, 400 MHz antenna was also used. GPR system was initialized in the field so that the ground reality, related to geo-electrical conditions of the field...

  11. High-resolution, high-sensitivity, ground-based solar spectropolarimetry with a new fast imaging polarimeter

    CERN Document Server

    Iglesias, F A; Nagaraju, K; Solanki, S K

    2016-01-01

    Context. Remote sensing of weak and small-scale solar magnetic fields is of utmost relevance for a number of important open questions in solar physics. This requires the acquisition of spectropolarimetric data with high spatial resolution (0.1 arcsec) and low noise (1e-3 to 1e-5 of the continuum intensity). The main limitations to obtain these measurements from the ground, are the degradation of the image resolution produced by atmospheric seeing and the seeing-induced crosstalk (SIC). Aims. We introduce the prototype of the Fast Solar Polarimeter (FSP), a new ground-based, high-cadence polarimeter that tackles the above-mentioned limitations by producing data that are optimally suited for the application of post-facto image restoration, and by operating at a modulation frequency of 100 Hz to reduce SIC. Results. The pnCCD camera reaches 400 fps while keeping a high duty cycle (98.6 %) and very low noise (4.94 erms). The modulator is optimized to have high (> 80%) total polarimetric efficiency in the visible ...

  12. The pixelated detector

    CERN Multimedia

    Sutton, C

    1990-01-01

    "Collecting data as patterns of light or subatomic particles is vitally important in all the sciences. The new generation of solid-state detectors called pixel devices could transform experimental research at all levels" (4 pages).

  13. Ground mapping resolution accuracy of a scanning radiometer from a geostationary satellite.

    Science.gov (United States)

    Stremler, F G; Khalil, M A; Parent, R J

    1977-06-01

    Measures of the spatial and spatial rate (frequency) mapping of scanned visual imagery from an earth reference system to a spin-scan geostationary satellite are examined. Mapping distortions and coordinate inversions to correct for these distortions are formulated in terms of geometric transformations between earth and satellite frames of reference. Probabilistic methods are used to develop relations for obtainable mapping resolution when coordinate inversions are employed.

  14. Breaking New Ground with High Resolution Turn-By-Turn BPMs at the ESRF

    CERN Document Server

    Farvacque, L; Scheidt, K

    2001-01-01

    This High-Resolution, Turn-by-Turn BPM system is a low-cost extension to the existing BPM system, based on the RF-multiplexing concept, used for slow Closed-Orbit measurements. With this extension Beam Position measurements in both planes, at all (224) BPMs in the 844 m ESRF Storage Ring, for up to 2048 Orbit Turns with 1 μm resolution are performed. The data acquisition is synchronised to a single, flat 1 μs, transverse deflection kick to the 1μs beamfill in the 2.8μs revolution period. The high quality of this synchronisation, together with the good reproducibility of the deflection kick and the overall stability of the Closed Orbit beam allows to repeat the kick and acquisition in many cycles. The subsequent averaging of the data obtained in these cycles yields the 1um resolution. The latter allows lattice measurements with high precision such as the localisation of very small focussing errors and modulation in Beta values and phase advances. It also finds an unique ...

  15. High-resolution absorption spectroscopy of the OH 2Pi 3/2 ground state line

    CERN Document Server

    Wiesemeyer, Helmut; Heyminck, Stefan; Karl, Jacobs; Menten, Karl; Neufeld, David; Requena-Torres, Miguel Angel; Stutzki, Jürgen; 10.1051/0004-6361/201218915

    2012-01-01

    The chemical composition of the interstellar medium is determined by gas phase chemistry, assisted by grain surface reactions, and by shock chemistry. The aim of this study is to measure the abundance of the hydroxyl radical (OH) in diffuse spiral arm clouds as a contribution to our understanding of the underlying network of chemical reactions. Owing to their high critical density, the ground states of light hydrides provide a tool to directly estimate column densities by means of absorption spectroscopy against bright background sources. We observed onboard the SOFIA observatory the 2Pi3/2, J = 5/2 3/2 2.5 THz line of ground-state OH in the diffuse clouds of the Carina-Sagittarius spiral arm. OH column densities in the spiral arm clouds along the sightlines to W49N, W51 and G34.26+0.15 were found to be of the order of 10^14 cm^-2, which corresponds to a fractional abundance of 10^-7 to 10^-8, which is comparable to that of H_2O. The absorption spectra of both species have similar velocity components, and the...

  16. Effects of aging on figure-ground perception: Convexity context effects and competition resolution.

    Science.gov (United States)

    Lass, Jordan W; Bennett, Patrick J; Peterson, Mary A; Sekuler, Allison B

    2017-02-01

    We examined age-related differences in figure-ground perception by exploring the effect of age on Convexity Context Effects (CCE; Peterson & Salvagio, 2008). Experiment 1, using Peterson and Salvagio's procedure and black and white stimuli consisting of 2 to 8 alternating concave and convex regions, established that older adults exhibited reduced CCEs compared to younger adults. Experiments 2 and 3 demonstrated that this age difference was found at various stimulus durations and sizes. Experiment 4 compared CCEs obtained with achromatic stimuli, in which the alternating convex and concave regions were each all black or all white, and chromatic stimuli in which the concave regions were homogeneous in color but the convex regions varied in color. We found that the difference between CCEs measured with achromatic and colored stimuli was larger in older than in younger adults. Our results are consistent with the hypothesis that the senescent visual system is less able to resolve the competition among various perceptual interpretations of the figure-ground relations among stimulus regions.

  17. The ALICE pixel detector upgrade

    Science.gov (United States)

    Reidt, F.

    2016-12-01

    The ALICE experiment at the CERN LHC is designed to study the physics of strongly interacting matter, and in particular the properties of the Quark-Gluon Plasma, using proton-proton, proton-nucleus and nucleus-nucleus collisions. The ALICE collaboration is preparing a major upgrade of the experimental apparatus to be installed during the second long LHC shutdown in the years 2019-2020. A key element of the ALICE upgrade is the new, ultra-light, high-resolution Inner Tracking System. With respect to the current detector, the new Inner Tracking System will significantly enhance the pointing resolution, the tracking efficiency at low transverse momenta, and the read-out rate capabilities. This will be obtained by seven concentric detector layers based on a Monolithic Active Pixel Sensor with a pixel pitch of about 30×30 μm2. A key feature of the new Inner Tracking System, which is optimised for high tracking accuracy at low transverse momenta, is the very low mass of the three innermost layers, which feature a material budget of 0.3% X0 per layer. This contribution presents the design goals and layout of the upgraded ALICE Inner Tracking System, summarises the R&D activities focussing on the technical implementation of the main detector components, and the projected detector performance.

  18. Performance limits of a single photon counting pixel system

    Energy Technology Data Exchange (ETDEWEB)

    Chmeissani, M.; Mikulec, B. E-mail: bettina.mikulec@cern.ch

    2001-03-11

    X-ray imaging using hybrid pixel detectors in single photon counting mode is a relatively recent and exciting development. The photon counting mode implies that each pixel has a threshold in energy above which a hit is recorded. Sharing of charge between adjacent pixels would therefore lead to a loss of registered hits and for medical imaging applications to a higher patient dose. This explains why the demand for high spatial resolution and consequently small pixel sizes (<100 {mu}m) motivates the Medipix2 collaboration to study the effects of charge sharing between pixels on system performance. Two different simulation codes are used to simulate the energy loss inside the detector and the charge transport towards the pixel electrodes. The largest contribution to the lateral spreading of charge comes from diffusion and can result in a considerable loss of detection efficiency in photon counting systems for small pixel sizes.

  19. Effect of Pixel’s Spatial Characteristics on Recognition of Isolated Pixelized Chinese Character

    Science.gov (United States)

    Yang, Kun; Liu, Shuang; Wang, Hong; Liu, Wei; Wu, Yaowei

    2015-01-01

    The influence of pixel’s spatial characteristics on recognition of isolated Chinese character was investigated using simulated prosthestic vision. The accuracy of Chinese character recognition with 4 kinds of pixel number (6*6, 8*8, 10*10, and 12*12 pixel array) and 3 kinds of pixel shape (Square, Dot and Gaussian) and different pixel spacing were tested through head-mounted display (HMD). A captured image of Chinese characters in font style of Hei were pixelized with Square, Dot and Gaussian pixel. Results showed that pixel number was the most important factor which could affect the recognition of isolated pixelized Chinese Chartars and the accuracy of recognition increased with the addition of pixel number. 10*10 pixel array could provide enough information for people to recognize an isolated Chinese character. At low resolution (6*6 and 8*8 pixel array), there were little difference of recognition accuracy between different pixel shape and different pixel spacing. While as for high resolution (10*10 and 12*12 pixel array), the fluctuation of pixel shape and pixel spacing could not affect the performance of recognition of isolated pixelized Chinese Character. PMID:26628934

  20. Finding extraterrestrial life using ground-based high-resolution spectroscopy

    CERN Document Server

    Snellen, Ignas; Poole, Rudolf Le; Brogi, Matteo; Birkby, Jayne

    2013-01-01

    Exoplanet observations promise one day to unveil the presence of extraterrestrial life. Atmospheric compounds in strong chemical disequilibrium would point to large-scale biological activity just as oxygen and methane do in the Earth's atmosphere. The cancellation of both the Terrestrial Planet Finder and Darwin missions means that it is unlikely that a dedicated space telescope to search for biomarker gases in exoplanet atmospheres will be launched within the next 25 years. Here we show that ground-based telescopes provide a strong alternative for finding biomarkers in exoplanet atmospheres through transit observations. Recent results on hot Jupiters show the enormous potential of high-dispersion spectroscopy to separate the extraterrestrial and telluric signals making use of the Doppler shift of the planet. The transmission signal of oxygen from an Earth-twin orbiting a small red dwarf star is only a factor 3 smaller than that of carbon monoxide recently detected in the hot Jupiter tau Bootis b, albeit such...

  1. Dense Iterative Contextual Pixel Classification using Kriging

    DEFF Research Database (Denmark)

    Ganz, Melanie; Loog, Marco; Brandt, Sami

    2009-01-01

    have been proposed to this end, e.g., iterative contextual pixel classification, iterated conditional modes, and other approaches related to Markov random fields. A problem of these methods, however, is their computational complexity, especially when dealing with high-resolution images in which...

  2. Using HyspIRI Campaign Data for Sub-pixel Classification of the Urban Land Surface

    Science.gov (United States)

    Wetherley, E. B.; Roberts, D. A.; McFadden, J. P.

    2015-12-01

    Quantifying urban ecosystem characteristics and dynamics requires accurate characterization of urban surfaces, which is complicated by the spectral similarity and surface heterogeneity of urban materials. In the late summer of 2014, visible near infrared/shortwave infrared imagery was acquired over the Santa Barbara, CA, urban area by the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) (18 m resolution, 224 bands, 0.35 - 2.5 μm) and AVIRIS-Next Generation (4 m resolution, 432 bands, 0.35 - 2.5 μm). We developed spectral libraries of urban image endmembers at both 4 m and 18 m, and then applied them to the 18 m imagery using Multiple Endmember Spectral Mixture Analysis (MESMA) to produce a classified map and sub-pixel fractions of impervious ground surfaces, roofs, irrigated grass, trees, senesced vegetation, and soil. Final products were validated using 1m resolution aerial imagery. Sub-pixel fraction results show that broad, ecologically important classes were assessed at a relatively high degree of accuracy. These classes include modeled green vegetation and impervious surface fractions (r2 > 0.85) and a combined senesced vegetation and soil (r2 > 0.70). Sub-classes of vegetation (trees, irrigated grass, and senesced vegetation) were also detectable, indicating the possibility for refined inputs for future urban ecological studies. MESMA results showed that the majority (> 85%) of the 18 m scale image was mapped with one or two endmembers (plus shade). Furthermore, endmembers extracted from higher spatial resolution imagery (4 m) did not yield a detectable increase in sub-pixel accuracy. Overall, these results indicate that the 18 m spatial resolution imagery was adequate to capture these broad urban classes at the sub-pixel level.

  3. Simulation study of pixel detector charge digitization

    Science.gov (United States)

    Wang, Fuyue; Nachman, Benjamin; Sciveres, Maurice; Lawrence Berkeley National Laboratory Team

    2017-01-01

    Reconstruction of tracks from nearly overlapping particles, called Tracking in Dense Environments (TIDE), is an increasingly important component of many physics analyses at the Large Hadron Collider as signatures involving highly boosted jets are investigated. TIDE makes use of the charge distribution inside a pixel cluster to resolve tracks that share one of more of their pixel detector hits. In practice, the pixel charge is discretized using the Time-over-Threshold (ToT) technique. More charge information is better for discrimination, but more challenging for designing and operating the detector. A model of the silicon pixels has been developed in order to study the impact of the precision of the digitized charge distribution on distinguishing multi-particle clusters. The output of the GEANT4-based simulation is used to train neutral networks that predict the multiplicity and location of particles depositing energy inside one cluster of pixels. By studying the multi-particle cluster identification efficiency and position resolution, we quantify the trade-off between the number of ToT bits and low-level tracking inputs. As both ATLAS and CMS are designing upgraded detectors, this work provides guidance for the pixel module designs to meet TIDE needs. Work funded by the China Scholarship Council and the Office of High Energy Physics of the U.S. Department of Energy under contract DE-AC02-05CH11231.

  4. A noiseless kilohertz frame rate imaging detector based on microchannel plates read out with the Medipix2 CMOS pixel chip

    CERN Document Server

    Mikulec, Bettina; Ferrère, Didier; La Marra, Daniel; McPhate, J B; Tremsin, A S; Siegmund, O H W; Vallerga, J V; Clement, J; Ponchut, C; Rigal, J M; CERN. Geneva

    2006-01-01

    A new hybrid optical imaging detector is described that is being developed for the next generation adaptive optics (AO) wavefront sensors (WFS) for ground-based telescopes. The detector consists of a photocathode and proximity focused microchannel plates (MCPs) read out by the Medipix2 CMOS pixel ASIC. Each pixel of the Medipix2 device measures 55x55 um2 and comprises pre-amplifier, a window discriminator and a 14-bit counter. The 256x256 Medipix2 array can be read out noiselessly in 287 us. The readout can be electronically shuttered down to a temporal window of a few us. The Medipix2 is buttable on 3 sides to produce 512x(n*256) pixel devices. Measurements with ultraviolet light yield a spatial resolution of the detector at the Nyquist limit. Sub-pixel resolution can be achieved using centroiding algorithms. For the AO application, very high continuous frame rates of the order of 1 kHz are required for a matrix of 512x512 pixels. The design concepts of a parallel readout board are presented that will allow ...

  5. Pixel super resolution using wavelength scanning

    Science.gov (United States)

    2016-04-08

    implementation, the iterations did not use either GPU ( graphics processing unit) or parallel computing , which could significantly improve our overall...2 Tsai RY, Huang TS. Multiframe Image Restoration and Registration. Adv Comput Vis Image Process 1984; 1: 317–339. 3 Hardie RC, Barnard KJ, Bognar JG...lensfree computational imaging , on-chip imaging , holographic imaging REPORT DOCUMENTATION PAGE 11. SPONSOR/MONITOR’S REPORT NUMBER(S) 10. SPONSOR

  6. Towards a new generation of pixel detector readout chips

    CERN Document Server

    Campbell, M; Ballabriga, R.; Frojdh, E.; Heijne, E.; Llopart, X.; Poikela, T.; Tlustos, L.; Valerio, P.; Wong, W.

    2016-01-01

    The Medipix3 Collaboration has broken new ground in spectroscopic X-ray imaging and in single particle detection and tracking. This paper will review briefly the performance and limitations of the present generation of pixel detector readout chips developed by the Collaboration. Through Silicon Via technology has the potential to provide a significant improvement in the tile- ability and more flexibility in the choice of readout architecture. This has been explored in the context of 3 projects with CEA-LETI using Medipix3 and Timepix3 wafers. The next generation of chips will aim to provide improved spectroscopic imaging performance at rates compatible with human CT. It will also aim to provide full spectroscopic images with unprecedented energy and spatial resolution. Some of the opportunities and challenges posed by moving to a more dense CMOS process will be discussed.

  7. Evaluation of Six High-Resolution Satellite and Ground-Based Precipitation Products over Malaysia

    Directory of Open Access Journals (Sweden)

    Mou Leong Tan

    2015-01-01

    Full Text Available Satellite precipitation products (SPPs potentially constitute an alternative to sparse rain gauge networks for assessing the spatial distribution of precipitation. However, applications of these products are still limited due to the lack of robust quality assessment. This study compares daily, monthly, seasonal, and annual rainfall amount at 342 rain gauges over Malaysia to estimations using five SPPs (3B42RT, 3B42V7, GPCP-1DD, PERSIANN-CDR, and CMORPH and a ground-based precipitation product (APHRODITE. The performance of the precipitation products was evaluated from 2003 to 2007 using continuous (RMSE, R2, ME, MAE, and RB and categorical (ACC, POD, FAR, CSI, and HSS statistical approaches. Overall, 3B42V7 and APHRODITE performed the best, while the worst performance was shown by GPCP-1DD. 3B42RT, 3B42V7, and PERSIANN-CDR slightly overestimated observed precipitation by 2%, 4.7%, and 2.1%, respectively. By contrast, APHRODITE and CMORPH significantly underestimated precipitations by 19.7% and 13.2%, respectively, whereas GPCP-1DD only slightly underestimated by 2.8%. All six precipitation products performed better in the northeast monsoon than in the southwest monsoon. The better performances occurred in eastern and southern Peninsular Malaysia and in the north of East Malaysia, which receives higher rainfall during the northeast monsoon, whereas poor performances occurred in the western and dryer Peninsular Malaysia. All precipitation products underestimated the no/tiny (<1 mm/day and extreme (≥20 mm/day rainfall events, while they overestimated low (1–20 mm/day rainfall events. 3B42RT and 3B42V7 showed the best ability to detect precipitation amounts with the highest HSS value (0.36. Precipitations during flood events such as those which occurred in late 2006 and early 2007 were estimated the best by 3B42RT and 3B42V7, as shown by an R2 value ranging from 0.49 to 0.88 and 0.52 to 0.86, respectively. These results on SPPs’ uncertainties

  8. Pixel detector insertion

    CERN Multimedia

    CMS

    2015-01-01

    Insertion of the Pixel Tracker, the 66-million-channel device used to pinpoint the vertex of each colliding proton pair, located at the heart of the detector. The geometry of CMS is a cylinder lying on its side (22 meters long and 15 meters high in dia

  9. Pixel detector readout chip

    CERN Multimedia

    1991-01-01

    Close-up of a pixel detector readout chip. The photograph shows an aera of 1 mm x 2 mm containing 12 separate readout channels. The entire chip contains 1000 readout channels (around 80 000 transistors) covering a sensitive area of 8 mm x 5 mm. The chip has been mounted on a silicon detector to detect high energy particles.

  10. ALICE Silicon Pixel Detector

    CERN Multimedia

    Manzari, V

    2013-01-01

    The Silicon Pixel Detector (SPD) forms the innermost two layers of the 6-layer barrel Inner Tracking System (ITS). The SPD plays a key role in the determination of the position of the primary collision and in the reconstruction of the secondary vertices from particle decays.

  11. Tropospheric and total ozone columns over Paris (France) measured using medium-resolution ground-based solar-absorption Fourier-transform infrared spectroscopy

    OpenAIRE

    C. Viatte; B. Gaubert; Eremenko, M.; Hase, F.; Schneider, M; Blumenstock, T.; Ray, M; P. Chelin; J.-M. Flaud; Orphal, J

    2011-01-01

    Ground-based Fourier-transform infrared (FTIR) solar absorption spectroscopy is a powerful remote sensing technique providing information on the vertical distribution of various atmospheric constituents. This work presents the first evaluation of a mid-resolution ground-based FTIR to measure tropospheric ozone, independently of stratospheric ozone. This is demonstrated using a new atmospheric observatory (named OASIS for "Observations of the Atmosphere by Solar absorption Infrared Spectroscop...

  12. Tropospheric and total ozone columns over Paris (France) measured using medium-resolution ground-based solar-absorption Fourier-transform infrared spectroscopy [Discussion paper

    OpenAIRE

    C. Viatte; B. Gaubert; Eremenko, M.; Hase, F.; Schneider, M; Blumenstock, T.; Ray, M; P. Chelin; J.-M. Flaud; Orphal, J

    2011-01-01

    Ground-based Fourier-transform infrared (FTIR) solar absorption spectroscopy is a powerful remote sensing technique providing information on the vertical distribution of various atmospheric constituents. This work presents the first evaluation of a mid-resolution ground-based FTIR to measure tropospheric ozone, independently of stratospheric ozone. This is demonstrated using a new atmospheric observatory (named OASIS for "Observations of the Atmosphere by Solar absorption Infrared Spectroscop...

  13. Monolithic CMOS pixel detector for international linear collider vertex detection

    Indian Academy of Sciences (India)

    J E Brau; O Igonkina; N Sinew; D Strom; C Baltay; W Emmet; H Neal; D Rabinowitz

    2007-12-01

    A monolithic CMS pixel detector is under development for an ILC experiment. This chronopixel array provides a time stamp resolution of one bunch crossing, a critical feature for background suppression. The status of this effort is summarized.

  14. High resolution imaging of vadose zone transport using surface and crosswell ground penetrating radar methods

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Kenneth H.; Kowalsky, Mike B.; Peterson, John E.

    2002-11-05

    -groundwater system control flow geometry? (2) What physical properties or mechanisms control flow and transport in unconsolidated soils of the vadose zone? (3) What is the optimum suite of field tests to provide information for predicting flow and transport behavior? (4) How can the information obtained during site characterization be used for building confidence in predictive numerical models? Fully developed, application of geophysics should enable location of contaminant distributions. Questions addressed in this study were the sensitivity, resolution, and accuracy of the geophysical methods in order to derive the spatial and temporal distribution of properties controlling transport and contaminant distribution between and away from boreholes and the surface. Implicit in this activity is that geophysical methods will be used to extrapolate and extend measurements made at the point scale to the volumetric scale. Overall there are two broad hypotheses being addressed in the geophysical work: (1) Geophysical methods can identify physical and chemical heterogeneity controlling contaminant transport at a meaningful scale. (2) Geophysical methods have the sensitivity to directly or indirectly detect the location of introduced fluids and/or contaminants at relevant concentrations (i.e. the subsurface has been altered from its natural state enough to create anomalies that can be detected in terms of a combination of mechanical, electrical, and thermal effects).

  15. A Proposed Extension to the Soil Moisture and Ocean Salinity Level 2 Algorithm for Mixed Forest and Moderate Vegetation Pixels

    Science.gov (United States)

    Panciera, Rocco; Walker, Jeffrey P.; Kalma, Jetse; Kim, Edward

    2011-01-01

    The Soil Moisture and Ocean Salinity (SMOS)mission, launched in November 2009, provides global maps of soil moisture and ocean salinity by measuring the L-band (1.4 GHz) emission of the Earth's surface with a spatial resolution of 40-50 km.Uncertainty in the retrieval of soilmoisture over large heterogeneous areas such as SMOS pixels is expected, due to the non-linearity of the relationship between soil moisture and the microwave emission. The current baseline soilmoisture retrieval algorithm adopted by SMOS and implemented in the SMOS Level 2 (SMOS L2) processor partially accounts for the sub-pixel heterogeneity of the land surface, by modelling the individual contributions of different pixel fractions to the overall pixel emission. This retrieval approach is tested in this study using airborne L-band data over an area the size of a SMOS pixel characterised by a mix Eucalypt forest and moderate vegetation types (grassland and crops),with the objective of assessing its ability to correct for the soil moisture retrieval error induced by the land surface heterogeneity. A preliminary analysis using a traditional uniform pixel retrieval approach shows that the sub-pixel heterogeneity of land cover type causes significant errors in soil moisture retrieval (7.7%v/v RMSE, 2%v/v bias) in pixels characterised by a significant amount of forest (40-60%). Although the retrieval approach adopted by SMOS partially reduces this error, it is affected by errors beyond the SMOS target accuracy, presenting in particular a strong dry bias when a fraction of the pixel is occupied by forest (4.1%v/v RMSE,-3.1%v/v bias). An extension to the SMOS approach is proposed that accounts for the heterogeneity of vegetation optical depth within the SMOS pixel. The proposed approach is shown to significantly reduce the error in retrieved soil moisture (2.8%v/v RMSE, -0.3%v/v bias) in pixels characterised by a critical amount of forest (40-60%), at the limited cost of only a crude estimate of the

  16. The pin pixel detector--neutron imaging

    CERN Document Server

    Bateman, J E; Derbyshire, G E; Duxbury, D M; Marsh, A S; Rhodes, N J; Schooneveld, E M; Simmons, J E; Stephenson, R

    2002-01-01

    The development and testing of a neutron gas pixel detector intended for application in neutron diffraction studies is reported. Using standard electrical connector pins as point anodes, the detector is based on a commercial 100 pin connector block. A prototype detector of aperture 25.4 mmx25.4 mm has been fabricated, giving a pixel size of 2.54 mm which matches well to the spatial resolution typically required in a neutron diffractometer. A 2-Dimensional resistive divide readout system has been adapted to permit the imaging properties of the detector to be explored in advance of true pixel readout electronics. The timing properties of the device match well to the requirements of the ISIS-pulsed neutron source.

  17. Development of CMOS Pixel Sensors fully adapted to the ILD Vertex Detector Requirements

    CERN Document Server

    Winter, Marc; Besson, Auguste; Claus, Gilles; Dorokhov, Andrei; Goffe, Mathieu; Hu-Guo, Christine; Morel, Frederic; Valin, Isabelle; Voutsinas, Georgios; Zhang, Liang

    2012-01-01

    CMOS Pixel Sensors are making steady progress towards the specifications of the ILD vertex detector. Recent developments are summarised, which show that these devices are close to comply with all major requirements, in particular the read-out speed needed to cope with the beam related background. This achievement is grounded on the double- sided ladder concept, which allows combining signals generated by a single particle in two different sensors, one devoted to spatial resolution and the other to time stamp, both assembled on the same mechanical support. The status of the development is overviewed as well as the plans to finalise it using an advanced CMOS process.

  18. Serial pixel analog-to-digital converter (ADC)

    Science.gov (United States)

    Larson, Eric D.

    2010-02-01

    This method reduces the data path from the counter to the pixel register of the analog-to-digital converter (ADC) from as many as 10 bits to a single bit. The reduction in data path width is accomplished by using a coded serial data stream similar to a pseudo random number (PRN) generator. The resulting encoded pixel data is then decoded into a standard hexadecimal format before storage. The high-speed serial pixel ADC concept is based on the single-slope integrating pixel ADC architecture. Previous work has described a massively parallel pixel readout of a similar architecture. The serial ADC connection is similar to the state-of-the art method with the exception that the pixel ADC register is a shift register and the data path is a single bit. A state-of-the-art individual-pixel ADC uses a single-slope charge integration converter architecture with integral registers and "one-hot" counters. This implies that parallel data bits are routed among the counter and the individual on-chip pixel ADC registers. The data path bit-width to the pixel is therefore equivalent to the pixel ADC bit resolution.

  19. High-Resolution Precipitation Mapping in a Mountainous Watershed: Ground Truth for Evaluating Uncertainty in a National Precipitation Dataset

    Science.gov (United States)

    Daly, C.; Slater, M. E.; Roberti, J. A.; Laseter, S. H.; Swift, L. W.

    2016-12-01

    A 69-station, densely-spaced rain gauge network was maintained over the period 1951-1958 in the Coweeta Hydrologic Laboratory, located in the southern Appalachians in western North Carolina, USA. This unique dataset was used to develop the first digital seasonal and annual precipitation maps for the Coweeta basin, using elevation regression functions and residual interpolation. It was found that a 10-m elevation grid filtered to an approximately 7-km effective wavelength explained the most variance in precipitation (R2 = 0.82-0.95). A "dump zone" of locally high precipitation a short distance downwind from the mountain crest marking the southern border of the basin was the main feature that was not explained well by the precipitation-elevation relationship. These data and maps provided a rare "ground-truth" for estimating uncertainty in the national-scale Parameter-elevation Relationships on Independent Slopes Model (PRISM) precipitation grids for this location and time period. Differences between PRISM and ground-truth were compared to uncertainty estimates produced by the PRISM model and cross-validation errors. Potential sources of uncertainty in the national PRISM grids were evaluated, including the effects of coarse grid resolution, limited station data, and imprecise station locations. The PRISM national grids matched closely (within five percent) with the Coweeta dataset. The PRISM regression prediction interval, which includes the influence of stations in an area of tens of km around a given location, overestimated the local error at Coweeta (12-20 percent). Offsetting biases and generally low error rates made it difficult to isolate major sources of uncertainty in the PRISM grids. However, station density and selection, and mis-location of stations were identified as likely sources of error. The methods used in this study can be repeated in other areas where high-density data exist to gain a more comprehensive picture of the uncertainties in national

  20. Geographic information system for fusion and analysis of high-resolution remote sensing and ground truth data

    Science.gov (United States)

    Freeman, Anthony; Way, Jo Bea; Dubois, Pascale; Leberl, Franz

    1992-01-01

    We seek to combine high-resolution remotely sensed data with models and ground truth measurements, in the context of a Geographical Information System, integrated with specialized image processing software. We will use this integrated system to analyze the data from two Case Studies, one at a bore Al forest site, the other a tropical forest site. We will assess the information content of the different components of the data, determine the optimum data combinations to study biogeophysical changes in the forest, assess the best way to visualize the results, and validate the models for the forest response to different radar wavelengths/polarizations. During the 1990's, unprecedented amounts of high-resolution images from space of the Earth's surface will become available to the applications scientist from the LANDSAT/TM series, European and Japanese ERS-1 satellites, RADARSAT and SIR-C missions. When the Earth Observation Systems (EOS) program is operational, the amount of data available for a particular site can only increase. The interdisciplinary scientist, seeking to use data from various sensors to study his site of interest, may be faced with massive difficulties in manipulating such large data sets, assessing their information content, determining the optimum combinations of data to study a particular parameter, visualizing his results and validating his model of the surface. The techniques to deal with these problems are also needed to support the analysis of data from NASA's current program of Multi-sensor Airborne Campaigns, which will also generate large volumes of data. In the Case Studies outlined in this proposal, we will have somewhat unique data sets. For the Bonanza Creek Experimental Forest (Case I) calibrated DC-8 SAR data and extensive ground truth measurement are already at our disposal. The data set shows documented evidence to temporal change. The Belize Forest Experiment (Case II) will produce calibrated DC-8 SAR and AVIRIS data, together with

  1. Geographic information system for fusion and analysis of high-resolution remote sensing and ground truth data

    Science.gov (United States)

    Freeman, Anthony; Way, Jo Bea; Dubois, Pascale; Leberl, Franz

    1992-01-01

    We seek to combine high-resolution remotely sensed data with models and ground truth measurements, in the context of a Geographical Information System, integrated with specialized image processing software. We will use this integrated system to analyze the data from two Case Studies, one at a bore Al forest site, the other a tropical forest site. We will assess the information content of the different components of the data, determine the optimum data combinations to study biogeophysical changes in the forest, assess the best way to visualize the results, and validate the models for the forest response to different radar wavelengths/polarizations. During the 1990's, unprecedented amounts of high-resolution images from space of the Earth's surface will become available to the applications scientist from the LANDSAT/TM series, European and Japanese ERS-1 satellites, RADARSAT and SIR-C missions. When the Earth Observation Systems (EOS) program is operational, the amount of data available for a particular site can only increase. The interdisciplinary scientist, seeking to use data from various sensors to study his site of interest, may be faced with massive difficulties in manipulating such large data sets, assessing their information content, determining the optimum combinations of data to study a particular parameter, visualizing his results and validating his model of the surface. The techniques to deal with these problems are also needed to support the analysis of data from NASA's current program of Multi-sensor Airborne Campaigns, which will also generate large volumes of data. In the Case Studies outlined in this proposal, we will have somewhat unique data sets. For the Bonanza Creek Experimental Forest (Case I) calibrated DC-8 SAR data and extensive ground truth measurement are already at our disposal. The data set shows documented evidence to temporal change. The Belize Forest Experiment (Case II) will produce calibrated DC-8 SAR and AVIRIS data, together with

  2. Dual readout 3D direct/induced-signals pixel systems

    CERN Document Server

    Parker, Sherwood; Deile, Mario; Hansen, Thor-Erik; Hasi, Jasmine; Kenney, Christopher; Kok, Angela; Watts, Stephen

    2008-01-01

    In this paper, 3D-electrode pixel detectors are described, in which the bias electrode systems have additional elements. Adding resistors between the bias supply line and each bias electrode together with a signal electrode readout that can measure pulse heights of both polarities could simultaneously provide lower capacitance and improved spatial resolution in both directions. A separate paper (“Dual-readout—strip/pixel systems”) covers an alternative—pixels with an added strip readout in one direction which could be used with either planar or 3D-electrodes, and could simultaneously provide a fast trigger and significantly increase the spatial resolution in both directions.

  3. ATLAS ITk Pixel detector

    CERN Document Server

    Gemme, Claudia; The ATLAS collaboration

    2016-01-01

    The high luminosity upgrade of the LHC (HL-LHC) in 2026 will provide new challenge to the ATLAS tracker. The current inner detector will be replaced with a whole silicon tracker which will consist of a five barrel layer Pixel detector surrounded by a four barrel layer Strip detector. The expected high radiation level are requiring the development of upgraded silicon sensors as well as new a front-end chip. The dense tracking environment will require finer granularity detectors. The data rates will require new technologies for high bandwidth data transmission and handling. The current status of the HL-LHC ATLA Pixel detector developments as well as the various layout options will be reviewed.

  4. Alpine Pixel Detector Layout

    CERN Document Server

    Delebecque, P; The ATLAS collaboration; Geffroy, N; Massol, N; Rambure, T; Todorov, T

    2013-01-01

    A description of an optimized layout of pixel sensors based on a stave that combines both barrel and endcap module orientations. The mechanical stiffness of the structure is provided by carbon fiber shells spaced by carbon foam. The cooling of the modules is provided by two-phase $CO_{2}$ flowing in a thin titanium pipe glued inside the carbon fiber foam. The electrical services of all modules are provided by a single stave flex. This layout eliminates the need for separate barrel and endcap detector structures, and therefore the barrel services material in front of the endcap. The transition from barrel to endcap module orientation is optimized separately for each layer in order to minimize the active pixel area and the traversed material. The sparse module spacing in the endcap part of the stave allows for multiple fixation points, and for a stiff overall structure composed only of staves interconnected by stiff disks.

  5. High-Resolution Mapping of Sea Ice, Icebergs and Growlers in Kongsfjorden, Svalbard, using Ground Based Radar, Satellite, and UAV

    Science.gov (United States)

    Lauknes, T. R.; Rouyet, L.; Solbø, S. A.; Sivertsen, A.; Storvold, R.; Akbari, V.; Negrel, J.; Gerland, S.

    2016-12-01

    The dynamics of sea ­ice has a well­ recognized role in the climate system and its extent and evolution is impacted by the global warming. In addition, calving of icebergs and growlers at the tidewater glacier fronts is a component of the mass loss in polar regions. Understanding of calving and ice ­ocean interaction, in particular at tidewater glacier front remains elusive, and a problematic uncertainty in climate change projections. Studying the distribution, volumetry and motion of sea ­ice, icebergs and growlers is thus essential to understand their interactions with the environment in order to be able to predict at short­term their drifts, e.g. to mitigate the risk for shipping, and at longer term the multiple relations with climate changes. Here, we present the results from an arctic fieldwork campaign conducted in Kongsfjorden, Svalbard in April 2016, where we used different remote sensing instruments to observe dynamics of sea ice, icebergs, and growlers. We used a terrestrial radar system, imaging the study area every second minute during the observation period. At the front of the Kronebreen glacier, calving events can be detected and the drift of the generated icebergs and growlers tracked with unprecedented spatial and temporal resolution. During the field campaign, we collected four Radarsat-2 quad-pol images, that will be used to classify the different types of sea ice. In addition, we used small unmanned aircraft (UAS) instrumented with high resolution cameras capturing HD video and still pictures. This allows to map and measure the size of icebergs and ice floes. Such information is essential to validate sensitivity and detection limits from the ground and satellite based measurements.

  6. Clinical, pathological, and radiological characteristics of solitary ground-glass opacity lung nodules on high-resolution computed tomography

    Directory of Open Access Journals (Sweden)

    Qiu ZX

    2016-09-01

    Full Text Available Zhi-Xin Qiu,1 Yue Cheng,1 Dan Liu,1 Wei-Ya Wang,2 Xia Wu,2 Wei-Lu Wu,2 Wei-Min Li1,2 1Department of Respiratory Medicine, 2Department of Pathology, West China Hospital, Sichuan University, Chengdu, People’s Republic of China Background: Lung nodules are being detected at an increasing rate year by year with high-resolution computed tomography (HRCT being widely used. Ground-glass opacity nodule is one of the special types of pulmonary nodules that is confirmed to be closely associated with early stage of lung cancer. Very little is known about solitary ground-glass opacity nodules (SGGNs. In this study, we analyzed the clinical, pathological, and radiological characteristics of SGGNs on HRCT.Methods: A total of 95 resected SGGNs were evaluated with HRCT scan. The clinical, pathological, and radiological characteristics of these cases were analyzed.Results: Eighty-one adenocarcinoma and 14 benign nodules were observed. The nodules included 12 (15% adenocarcinoma in situ (AIS, 14 (17% minimally invasive adenocarcinoma (MIA, and 55 (68% invasive adenocarcinoma (IA. No patients with recurrence till date have been identified. The positive expression rates of anaplastic lymphoma kinase and ROS-1 (proto-oncogene tyrosine-protein kinase ROS were only 2.5% and 8.6%, respectively. The specificity and accuracy of HRCT of invasive lung adenocarcinoma were 85.2% and 87.4%. The standard uptake values of only two patients determined by 18F-FDG positron emission tomography/computed tomography (PET/CT were above 2.5. The size, density, shape, and pleural tag of nodules were significant factors that differentiated IA from AIS and MIA. Moreover, the size, shape, margin, pleural tag, vascular cluster, bubble-like sign, and air bronchogram of nodules were significant determinants for mixed ground-glass opacity nodules (all P<0.05.Conclusion: We analyzed the clinical, pathological, and radiological characteristics of SGGNs on HRCT and found that the size, density

  7. High-Resolution Analysis Products to Support Severe Weather and Cloud-to-Ground Lightning Threat Assessments over Florida

    Science.gov (United States)

    Case, Jonathan; Spratt, Scott; Sharp, David

    2006-01-01

    The Applied Meteorology Unit (AMU) located at the Kennedy Space Center (KSC)/Cape Canaveral Air Force Station (CCAFS) implemented an operational configuration of the Advanced Regional Prediction System (ARPS) Data Analysis System (ADAS), as well as the ARPS numerical weather prediction (NWP) model. Operational, high-resolution ADAS analyses have been produced from this configuration at the National Weather Service in Melbourne, FL (NWS MLB) and the Spaceflight Meteorology Group (SMG) over the past several years. Since that time, ADAS fields have become an integral part of forecast operations at both NWS MLB and SMG. To continue providing additional utility, the AMU has been tasked to implement visualization products to assess the potential for supercell thunderstorms and significant tornadoes, and to improve assessments of short-term cloud-to-ground (CG) lightning potential. This paper and presentation focuses on the visualization products developed by the AMU for the operational high-resolution ADAS and AR.PS at the NWS MLB and SMG. The two severe weather threat graphics implemented within ADAS/ARPS are the Supercell Composite Parameter (SCP) and Significant Tornado Parameter (SIP). The SCP was designed to identify areas with supercell thunderstorm potential through a combination of several instability and shear parameters. The SIP was designed to identify areas that favor supercells producing significant tornadoes (F2 or greater intensity) versus non-tornadic supercells. Both indices were developed by the NOAAINWS Storm Prediction Center (SPC) and were normalized by key threshold values based on previous studies. The indices apply only to discrete storms, not other convective modes. In a post-analysis mode, the AMU calculated SCP and SIP for graphical output using an ADAS configuration similar to the operational set-ups at NWS MLB and SMG. Graphical images from ADAS were generated every 15 minutes for 13 August 2004, the day that Hurricane Charley approached and

  8. Electrical Characteristics of Silicon Pixel Sensors

    CERN Document Server

    Gorelov, I; Hoeferkamp, M; Mata-Bruni, V; Santistevan, G; Seidel, S C; Ciocio, A; Einsweiler, K F; Emes, J; Gilchriese, M G D; Joshi, A; Kleinfelder, S A; Marchesini, R; McCormack, F; Milgrome, O; Palaio, N; Pengg, F; Richardson, J; Zizka, G; Ackers, M; Comes, G; Fischer, P; Keil, M; Klasen, V; Kühl, T; Meuser, S; Ockenfels, W; Raith, B; Treis, J; Wermes, N; Gössling, C; Hügging, F G; Klaiber Lodewigs, Jonas M; Krasel, O; Wüstenfeld, J; Wunstorf, R; Barberis, D; Beccherle, R; Caso, Carlo; Cervetto, M; Darbo, G; Gagliardi, G; Gemme, C; Morettini, P; Netchaeva, P; Osculati, B; Rossi, L; Charles, E; Fasching, D; Blanquart, L; Breugnon, P; Calvet, D; Clemens, J-C; Delpierre, P A; Hallewell, G D; Laugier, D; Mouthuy, T; Rozanov, A; Valin, I; Andreazza, A; Caccia, M; Citterio, M; Lari, T; Meroni, C; Ragusa, F; Troncon, C; Vegni, G; Lutz, Gerhard; Richter, R H; Rohe, T; Boyd, GR; Skubic, P L; Sícho, P; Tomasek, L; Vrba, V; Holder, M; Ziolkowski, M; Cauz, D; Cobal-Grassmann, M; D'Auria, S; De Lotto, B; del Papa, C; Grassmann, H; Santi, L; Becks, K H; Lenzen, G; Linder, C

    2001-01-01

    Prototype sensors for the ATLAS silicon pixel detector have been electrically characterized. The current and voltage characteristics, charge collection efficiencies, and resolutions have been examined. Devices were fabricated on oxygenated and standard detector-grade silicon wafers. Results from prototypes which examine p-stop and standard and moderated p-spray isolation are presented for a variety of geometrical options. Some of the comparisons relate unirradiated sensors with those that have received fluences relevant to LHC operation.

  9. ATLAS-IBL Pixel Upgrade

    CERN Document Server

    LaRosa, A; The ATLAS collaboration

    2010-01-01

    The upgrade for the ATLAS detector will undergo different phase towards Super-LHC. The first upgrade for the Pixel Detector will consist in the construction of a new pixel layer which will be installed during the first shutdown of the LHC machine (SLHC Phase I). The new detector, called Insertable B-Layer (IBL), will be inserted between the existing pixel detector and a new (smaller radius) beam-pipe at a radius of 3.2 cm. The IBL will require the development of several new technologies to cope with increase of radiation or pixel occupancy and also to improve the physics performance which will be achieved by reduction of the pixel size and of the material budget. Three different promising sensor technologies (Planar-Si, 3D-Si and Diamond) are currently under investigation for the pixel detector. An overview of the project with particular emphasis on pixel module studies, irradiation and beam test plans will be presented.

  10. Sensor development for the CMS pixel detector

    CERN Document Server

    Bölla, G; Horisberger, R P; Kaufmann, R; Rohe, T; Roy, A

    2002-01-01

    The CMS experiment which is currently under construction at the Large Hadron Collider (LHC) at CERN (Geneva, Switzerland) will contain a pixel detector which provides in its final configuration three space points per track close to the interaction point of the colliding beams. Because of the harsh radiation environment of the LHC, the technical realization of the pixel detector is extremely challenging. The readout chip as the most damageable part of the system is believed to survive a particle fluence of 6x10 sup 1 sup 4 n sub e sub q /cm sup 2 (All fluences are normalized to 1 MeV neutrons and therefore all components of the hybrid pixel detector have to perform well up to at least this fluence. As this requires a partially depleted operation of the silicon sensors after irradiation-induced type inversion of the substrate, an ''n in n'' concept has been chosen. In order to perform IV-tests on wafer level and to hold accidentally unconnected pixels close to ground potential, a resistive path between the pixe...

  11. Microlens performance limits in sub-2mum pixel CMOS image sensors.

    Science.gov (United States)

    Huo, Yijie; Fesenmaier, Christian C; Catrysse, Peter B

    2010-03-15

    CMOS image sensors with smaller pixels are expected to enable digital imaging systems with better resolution. When pixel size scales below 2 mum, however, diffraction affects the optical performance of the pixel and its microlens, in particular. We present a first-principles electromagnetic analysis of microlens behavior during the lateral scaling of CMOS image sensor pixels. We establish for a three-metal-layer pixel that diffraction prevents the microlens from acting as a focusing element when pixels become smaller than 1.4 microm. This severely degrades performance for on and off-axis pixels in red, green and blue color channels. We predict that one-metal-layer or backside-illuminated pixels are required to extend the functionality of microlenses beyond the 1.4 microm pixel node.

  12. Modelling semiconductor pixel detectors

    CERN Document Server

    Mathieson, K

    2001-01-01

    expected after 200 ps in most cases. The effect of reducing the charge carrier lifetime and examining the charge collection efficiency has been utilised to explore how these detectors would respond in a harsh radiation environment. It is predicted that over critical carrier lifetimes (10 ps to 0.1 ns) an improvement of 40 % over conventional detectors can be expected. This also has positive implications for fabricating detectors, in this geometry, from materials which might otherwise be considered substandard. An analysis of charge transport in CdZnTe pixel detectors has been performed. The analysis starts with simulation studies into the formation of contacts and their influence on the internal electric field of planar detectors. The models include a number of well known defect states and these are balanced to give an agreement with a typical experimental I-V curve. The charge transport study extends to the development of a method for studying the effect of charge sharing in highly pixellated detectors. The ...

  13. Developing an Ice Volume Estimate of Jarvis Glacier, Alaska, using Ground-Penetrating Radar and High Resolution Satellite Imagery

    Science.gov (United States)

    Wu, N. L.; Campbell, S. W.; Douglas, T. A.; Osterberg, E. C.

    2013-12-01

    Jarvis Glacier is an important water source for Fort Greely and Delta Junction, Alaska. Yet with warming summer temperatures caused by climate change, the glacier is melting rapidly. Growing concern of a dwindling water supply has caused significant research efforts towards determining future water resources from spring melt and glacier runoff which feeds the community on a yearly basis. The main objective of this project was to determine the total volume of the Jarvis Glacier. In April 2012, a centerline profile of the Jarvis Glacier and 15 km of 100 MHz ground-penetrating radar (GPR) profiles were collected in cross sections to provide ice depth measurements. These depth measurements were combined with an interpreted glacier boundary (depth = 0 m) from recently collected high resolution WorldView satellite imagery to estimate total ice volume. Ice volume was calculated at 0.62 km3 over a surface area of 8.82 km2. However, it is likely that more glacier-ice exists within Jarvis Glacier watershed considering the value calculated with GPR profiles accounts for only the glacier ice within the valley and not for the valley side wall ice. The GLIMS glacier area database suggests that the valley accounts for approximately 50% of the total ice covered watershed. Hence, we are currently working to improve total ice volume estimates which incorporate the surrounding valley walls. Results from this project will be used in conjunction with climate change estimates and hydrological properties downstream of the glacier to estimate future water resources available to Fort Greely and Delta Junction.

  14. DEPFET--a pixel device with integrated amplification

    CERN Document Server

    Neeser, W; Buchholz, P; Fischer, P; Holl, P; Kemmer, J; Klein, P; Koch, H; Löcker, M; Lutz, Gerhard; Matthäy, H; Strüder, L; Trimpl, M; Ulrici, J; Wermes, N

    2002-01-01

    In the DEPFET pixel concept, the absorbed radiation directly modulates the channel current of a p-JFET transistor being integrated into a fully depleted high ohmic silicon substrate in every pixel cell, offering very low noise operation at room temperature. Hence, DEPFET pixels open new possibilities in biomedical applications, but also have a potential in particle physics and astrophysics. Second prototype 50 mu mx50 mu m single pixels as well as large (64x64) DEPFET matrices have been successfully produced and operated confirming the low noise behavior (12e). Device studies as well as a full DEPFET pixel Bioscope system to be used in real-time digital autoradiography with excellent spatial and energy resolution for X-rays are presented.

  15. Neural network based cluster creation in the ATLAS Pixel Detector

    CERN Document Server

    Andreazza, A; The ATLAS collaboration

    2012-01-01

    The read-out from individual pixels on planar semi-conductor sensors are grouped into clusters to reconstruct the location where a charged particle passed through the sensor. The resolution given by individual pixel sizes is significantly improved by using the information from the charge sharing be- tween pixels. Such analog cluster creation techniques have been used by the ATLAS experiment for many years to obtain an excellent performance. How- ever, in dense environments, such as those inside high-energy jets, clusters have an increased probability of merging the charge deposited by multiple particles. Recently, a neural network based algorithm which estimates both the cluster position and whether a cluster should be split has been developed for the ATLAS Pixel Detector. The algorithm significantly reduces ambigui- ties in the assignment of pixel detector measurement to tracks and improves the position accuracy with respect to standard techniques by taking into account the 2-dimensional charge distribution.

  16. Multiport solid-state imager characterization at variable pixel rates

    Science.gov (United States)

    Yates, George J.; Albright, Kevin L.; Turko, Bojan T.

    1993-10-01

    The imaging performance of an 8-port Full Frame Transfer Charge Coupled Device (FFT CCD) as a function of several parameters including pixel clock rate is presented. The device, model CCD-13, manufactured by English Electric Valve (EEV), is a 512 X 512 pixel array designed with four individual programmable bidirectional serial registers and eight output amplifiers permitting simultaneous readout of eight segments (128 horizontal X 256 vertical pixels) of the array. The imager was evaluated in Los Alamos National Laboratory's High-Speed Solid-State Imager Test Station at true pixel rates as high as 50 MHz for effective imager pixel rates approaching 400 MHz from multiporting. Key response characteristics measured include absolute responsivity, Charge-Transfer-Efficiency (CTE), dynamic range, resolution, signal-to-noise ratio, and electronic and optical crosstalk among the eight video channels. Preliminary test results and data obtained from the CCD-13 are presented and the versatility/capabilities of the test station are reviewed.

  17. AN ITERATIVE PIXEL-LEVEL IMAGE MATCHING METHOD FOR MARS MAPPING USING APPROXIMATE ORTHOPHOTOS

    Directory of Open Access Journals (Sweden)

    X. Geng

    2017-07-01

    Full Text Available Mars mapping is essential to the scientific research of the red planet. The special terrain characteristics of Martian surface can be used to develop the targeted image matching method. In this paper, in order to generate high resolution Mars DEM, a pixel-level image matching method for Mars orbital pushbroom images is proposed. The main strategies of our method include: (1 image matching on approximate orthophotos; (2 estimating approximate value of conjugate points by using ground point coordinates of orthophotos; (3 hierarchical image matching; (4 generating DEM and approximate orthophotos at each pyramid level; (5 fast transformation from ground points to image points for pushbroom images. The derived DEM at each pyramid level is used as reference data for the generation of approximate orthophotos at the next pyramid level. With iterative processing, the generated DEM becomes more and more accurate and a very small search window is precise enough for the determination of conjugate points. The images acquired by High Resolution Stereo Camera (HRSC on European Mars Express were used to verify our method’s feasibility. Experiment results demonstrate that accurate DEM data can be derived with an acceptable time cost by pixel-level image matching.

  18. Fabrication and Test of Pixelated CZT Detectors with Different Pixel Pitches and Thicknesses

    CERN Document Server

    Li, Q; Dowkontt, P; Martín, J; Beilicke, M; Jung, I; Groza, M; Bürger, A; De Geronimo, G; Krawczynski, H

    2008-01-01

    The main methods grown Cadmium Zinc Telluride (CZT) crystals with high yield and excellent homogeneity are Modified Horizontal Bridgman (MHB) and High Pressure Bridgman (HPB) processes, respectively. In this contribution, the readout system based on two 32-channel NCI-ASICs for pixellated CZT detector arrays has been developed and tested. The CZT detectors supplied by Orbotech (MHB) and eV products (HPB) are tested by NCI-ASIC readout system. The CZT detectors have an array of 8x8 or 11x11 pixel anodes fabricated on the anode surface with the area up to 2 cm x2 cm and the thickness of CZT detectors ranges from 0.5 cm to 1 cm. Energy spectra resolution and electron mobility-lifetime products of 8x8 pixels CZT detector with different thicknesses have been investigated.

  19. Towards third generation pixel readout chips

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Sciveres, M., E-mail: mgarcia-sciveres@lbl.gov; Mekkaoui, A.; Ganani, D.

    2013-12-11

    We present concepts and prototyping results towards a third generation pixel readout chip. We consider the 130 nm feature size FE-I4 chip, in production for the ATLAS IBL upgrade, to be a second generation chip. A third generation chip would have to go significantly further. A possible direction is to make the IC design generic so that different experiments can configure it to meet significantly different requirements, without the need for everybody to develop their own ASIC from the ground up. In terms of target technology, a demonstrator 500-pixel matrix containing analog front ends only (no complex functionality), was designed and fabricated in 65 nm CMOS and irradiated with protons in December 2011 and May 2012.

  20. The ALICE pixel detector

    CERN Document Server

    Mercado Perez, J

    2002-01-01

    The present document is a brief summary of the performed activities during the 2001 Summer Student Programme at CERN under the Scientific Summer at Foreign Laboratories Program organized by the Particles and Fields Division of the Mexican Physical Society (Sociedad Mexicana de Fisica). In this case, the activities were related with the ALICE Pixel Group of the EP-AIT Division, under the supervision of Jeroen van Hunen, research fellow in this group. First, I give an introduction and overview to the ALICE experiment; followed by a description of wafer probing. A brief summary of the test beam that we had from July 13th to July 25th is given as well. (3 refs).

  1. Pixelated gamma detector

    Energy Technology Data Exchange (ETDEWEB)

    Dolinsky, Sergei Ivanovich; Yanoff, Brian David; Guida, Renato; Ivan, Adrian

    2016-12-27

    A pixelated gamma detector includes a scintillator column assembly having scintillator crystals and optical transparent elements alternating along a longitudinal axis, a collimator assembly having longitudinal walls separated by collimator septum, the collimator septum spaced apart to form collimator channels, the scintillator column assembly positioned adjacent to the collimator assembly so that the respective ones of the scintillator crystal are positioned adjacent to respective ones of the collimator channels, the respective ones of the optical transparent element are positioned adjacent to respective ones of the collimator septum, and a first photosensor and a second photosensor, the first and the second photosensor each connected to an opposing end of the scintillator column assembly. A system and a method for inspecting and/or detecting defects in an interior of an object are also disclosed.

  2. Planar Pixelations and Image Recognition

    CERN Document Server

    Rowekamp, Brandon

    2011-01-01

    Any subset of the plane can be approximated by a set of square pixels. This transition from a shape to its pixelation is rather brutal since it destroys geometric and topological information about the shape. Using a technique inspired by Morse Theory, we algorithmically produce a PL approximation of the original shape using only information from its pixelation. This approximation converges to the original shape in a very strong sense: as the size of the pixels goes to zero we can recover important geometric and topological invariants of the original shape such as Betti numbers, area, perimeter and curvature measures.

  3. Image Restoration After Pixel Binning in Image Sensors

    Institute of Scientific and Technical Information of China (English)

    LI Hao; ZHANG Hui; GUO Xiaolian; HU Guangshu

    2009-01-01

    A method was developed to restore degraded images to some extent after the pixel binning pro-cess in image sensors to improve the resolution. A pixel binning model was used to approximate the original un-binned image. Then, the least squares error criterion was used as a constraint to reconstruct the re-stored pixel values from the binning model. The technique achieves about a one-decibel increase in the peak signal-to-noise ratio compared with the odginal estimated image. The technique has good detail pre-servation performance as well as low computation load. Thus, this restoration technique provides valuable improvements in practical, real time image processing.

  4. Dual collection mode optical microscope with single-pixel detection

    Science.gov (United States)

    Rodríguez, A. D.; Clemente, P.; Fernández-Alonso, Mercedes; Tajahuerce, E.; Lancis, J.

    2015-07-01

    In this work we have developed a single-pixel optical microscope that provides both re ection and transmission images of the sample under test by attaching a diamond pixel layout DMD to a commercial inverted microscope. Our system performs simultaneous measurements of re ection and transmission modes. Besides, in contrast with a conventional system, in our single-element detection system both images belong, unequivocally, to the same plane of the sample. Furthermore, we have designed an algorithm to modify the shape of the projected patterns that improves the resolution and prevents the artifacts produced by the diamond pixel architecture.

  5. Hybrid Pixel Detectors for gamma/X-ray imaging

    Science.gov (United States)

    Hatzistratis, D.; Theodoratos, G.; Zografos, V.; Kazas, I.; Loukas, D.; Lambropoulos, C. P.

    2015-09-01

    Hybrid pixel detectors are made by direct converting high-Z semi-insulating single crystalline material coupled to complementary-metal-oxide semiconductor (CMOS) readout electronics. They are attractive because direct conversion exterminates all the problems of spatial localization related to light diffusion, energy resolution, is far superior from the combination of scintillation crystals and photomultipliers and lithography can be used to pattern electrodes with very fine pitch. We are developing 2-D pixel CMOS ASICs, connect them to pixilated CdTe crystals with the flip chip and bump bonding method and characterize the hybrids. We have designed a series of circuits, whose latest member consists of a 50×25 pixel array with 400um pitch and an embedded controller. In every pixel a full spectroscopic channel with time tagging information has been implemented. The detectors are targeting Compton scatter imaging and they can be used for coded aperture imaging too. Hybridization using CMOS can overcome the limit put on pixel circuit complexity by the use of thin film transistors (TFT) in large flat panels. Hybrid active pixel sensors are used in dental imaging and other applications (e.g. industrial CT etc.). Thus X-ray imaging can benefit from the work done on dynamic range enhancement methods developed initially for visible and infrared CMOS pixel sensors. A 2-D CMOS ASIC with 100um pixel pitch to demonstrate the feasibility of such methods in the context of X-ray imaging has been designed.

  6. Diamond pixel modules

    CERN Document Server

    Gan, K K; Robichaud, A; Potenza, R; Kuleshov, S; Kagan, H; Kass, R; Wermes, N; Dulinski, W; Eremin, V; Smith, S; Sopko, B; Olivero, P; Gorisek, A; Chren, D; Kramberger, G; Schnetzer, S; Weilhammer, P; Martemyanov, A; Hugging, F; Pernegger, H; Lagomarsino, S; Manfredotti, C; Mishina, M; Trischuk, W; Dobos, D; Cindro, V; Belyaev, V; Duris, J; Claus, G; Wallny, R; Furgeri, A; Tuve, C; Goldstein, J; Sciortino, S; Sutera, C; Asner, D; Mikuz, M; Lo Giudice, A; Velthuis, J; Hits, D; Griesmayer, E; Oakham, G; Frais-Kolbl, H; Bellini, V; D'Alessandro, R; Cristinziani, M; Barbero, M; Schaffner, D; Costa, S; Goffe, M; La Rosa, A; Bruzzi, M; Schreiner, T; de Boer, W; Parrini, G; Roe, S; Randrianarivony, K; Dolenc, I; Moss, J; Brom, J M; Golubev, A; Mathes, M; Eusebi, R; Grigoriev, E; Tsung, J W; Mueller, S; Mandic, I; Stone, R; Menichelli, D

    2011-01-01

    With the commissioning of the LHC in 2010 and upgrades expected in 2015, ATLAS and CMS are planning to upgrade their innermost tracking layers with radiation hard technologies. Chemical Vapor Deposition diamond has been used extensively in beam conditions monitors as the innermost detectors in the highest radiation areas of BaBar, Belle, CDF and all LHC experiments. This material is now being considered as a sensor material for use very close to the interaction region where the most extreme radiation conditions exist Recently the RD42 collaboration constructed, irradiated and tested polycrystalline and single-crystal chemical vapor deposition diamond sensors to the highest fluences expected at the super-LHC. We present beam test results of chemical vapor deposition diamond up to fluences of 1.8 x 10(16) protons/cm(2) illustrating that both polycrystalline and single-crystal chemical vapor deposition diamonds follow a single damage curve. We also present beam test results of irradiated complete diamond pixel m...

  7. Small pixel CZT detector for hard X-ray spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Matthew David, E-mail: Matt.Wilson@stfc.ac.uk [Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Oxfordshire OX11 0QX (United Kingdom); Cernik, Robert [Henry Moseley X-ray Imaging Facility, School of Materials, University of Manchester (United Kingdom); Chen, Henry [Redlen Technologies, Saanichton, British Columbia (Canada); Hansson, Conny [Henry Moseley X-ray Imaging Facility, School of Materials, University of Manchester (United Kingdom); Iniewski, Kris [Redlen Technologies, Saanichton, British Columbia (Canada); Jones, Lawrence L.; Seller, Paul; Veale, Matthew C. [Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Oxfordshire OX11 0QX (United Kingdom)

    2011-10-01

    A new small pixel cadmium zinc telluride (CZT) detector has been developed for hard X-ray spectroscopy. The X-ray performance of four detectors is presented and the detectors are analysed in terms of the energy resolution of each pixel. The detectors were made from CZT crystals grown by the travelling heater method (THM) bonded to a 20x20 application specific integrated circuit (ASIC) and data acquisition (DAQ) system. The detectors had an array of 20x20 pixels on a 250 {mu}m pitch, with each pixel gold-stud bonded to an energy resolving circuit in the ASIC. The DAQ system digitised the ASIC output with 14 bit resolution, performing offset corrections and data storage to disc in real time at up to 40,000 frames per second. The detector geometry and ASIC design was optimised for X-ray spectroscopy up to 150 keV and made use of the small pixel effect to preferentially measure the electron signal. A {sup 241}Am source was used to measure the spectroscopic performance and uniformity of the detectors. The average energy resolution (FWHM at 59.54 keV) of each pixel ranged from 1.09{+-}0.46 to 1.50{+-}0.57 keV across the four detectors. The detectors showed good spectral performance and uniform response over almost all pixels in the 20x20 array. A large area 80x80 pixel detector will be built that will utilise the scalable design of the ASIC and the large areas of monolithic spectroscopic grade THM grown CZT that are now available. The large area detector will have the same performance as that demonstrated here.

  8. Small pixel CZT detector for hard X-ray spectroscopy

    Science.gov (United States)

    Wilson, Matthew David; Cernik, Robert; Chen, Henry; Hansson, Conny; Iniewski, Kris; Jones, Lawrence L.; Seller, Paul; Veale, Matthew C.

    2011-10-01

    A new small pixel cadmium zinc telluride (CZT) detector has been developed for hard X-ray spectroscopy. The X-ray performance of four detectors is presented and the detectors are analysed in terms of the energy resolution of each pixel. The detectors were made from CZT crystals grown by the travelling heater method (THM) bonded to a 20×20 application specific integrated circuit (ASIC) and data acquisition (DAQ) system. The detectors had an array of 20×20 pixels on a 250 μm pitch, with each pixel gold-stud bonded to an energy resolving circuit in the ASIC. The DAQ system digitised the ASIC output with 14 bit resolution, performing offset corrections and data storage to disc in real time at up to 40,000 frames per second. The detector geometry and ASIC design was optimised for X-ray spectroscopy up to 150 keV and made use of the small pixel effect to preferentially measure the electron signal. A 241Am source was used to measure the spectroscopic performance and uniformity of the detectors. The average energy resolution (FWHM at 59.54 keV) of each pixel ranged from 1.09±0.46 to 1.50±0.57 keV across the four detectors. The detectors showed good spectral performance and uniform response over almost all pixels in the 20×20 array. A large area 80×80 pixel detector will be built that will utilise the scalable design of the ASIC and the large areas of monolithic spectroscopic grade THM grown CZT that are now available. The large area detector will have the same performance as that demonstrated here.

  9. Water erosion as a cause for agricultural soil loss: modeling of dynamic processes using high-resolution ground based LiDAR measurements

    Science.gov (United States)

    Oz, Imri; Filin, Sagi; Assouline, Shmuel; Shtain, Zachi; Furman, Alexander

    2016-04-01

    Soil erosion by rainfall and water flow is a frequent natural geomorphic process shaping the earth's surface at various scales. Conventional agrotechnical methods enhance soil erosion at the field scale and are at the origin of the reduction of the upper soil layer depth. This reduction is expressed in two aspects: decrease of soil depth, mainly due to erosion, and the diminution of soil quality, mainly due to the loss of fine material, nutrients and organic matter. Rain events, not even the most extremes, cause detachment and transport of fertile soil rich in organic matter and nutrients away from the fields, filling and plugging drainage channels, blocking infrastructure and contaminating water sources. Empirical, semi-empirical and mechanistic models are available to estimate soil erosion by water flow and sediment transport (e.g. WEPP, KINEROSS, EUROSEM). Calibration of these models requires data measured at high spatial and temporal resolutions. Development of high-resolution measurement tools (for both spatial and temporal aspects) should improve the calibration of functions related to particles detachment and transport from the soil surface. In addition, despite the great impact of different tillage systems on the soil erosion process, the vast majority of the models ignore this fundamental factor. The objective of this study is to apply high-resolution ground-based LiDAR measurements to different tillage schemes and scales to improve the ability of models to accurately describe the process of soil erosion induced by rainfall and overland flow. Ground-based laser scans provide high resolution accurate and subtle geomorphic changes, as well as larger-scale deformations. As such, it allows frequent monitoring, so that even the effect of a single storm can be measured, thus improving the calibration of the erosion models. Preliminary results for scans made in the field show the potential and limitations of ground-based LiDAR, and at this point qualitatively can

  10. Ground truth management system to support multispectral scanner /MSS/ digital analysis

    Science.gov (United States)

    Coiner, J. C.; Ungar, S. G.

    1977-01-01

    A computerized geographic information system for management of ground truth has been designed and implemented to relate MSS classification results to in situ observations. The ground truth system transforms, generalizes and rectifies ground observations to conform to the pixel size and shape of high resolution MSS aircraft data. These observations can then be aggregated for comparison to lower resolution sensor data. Construction of a digital ground truth array allows direct pixel by pixel comparison between classification results of MSS data and ground truth. By making comparisons, analysts can identify spatial distribution of error within the MSS data as well as usual figures of merit for the classifications. Use of the ground truth system permits investigators to compare a variety of environmental or anthropogenic data, such as soil color or tillage patterns, with classification results and allows direct inclusion of such data into classification operations. To illustrate the system, examples from classification of simulated Thematic Mapper data for agricultural test sites in North Dakota and Kansas are provided.

  11. From Pixels to Planets

    Science.gov (United States)

    Brownston, Lee; Jenkins, Jon M.

    2015-01-01

    The Kepler Mission was launched in 2009 as NASAs first mission capable of finding Earth-size planets in the habitable zone of Sun-like stars. Its telescope consists of a 1.5-m primary mirror and a 0.95-m aperture. The 42 charge-coupled devices in its focal plane are read out every half hour, compressed, and then downlinked monthly. After four years, the second of four reaction wheels failed, ending the original mission. Back on earth, the Science Operations Center developed the Science Pipeline to analyze about 200,000 target stars in Keplers field of view, looking for evidence of periodic dimming suggesting that one or more planets had crossed the face of its host star. The Pipeline comprises several steps, from pixel-level calibration, through noise and artifact removal, to detection of transit-like signals and the construction of a suite of diagnostic tests to guard against false positives. The Kepler Science Pipeline consists of a pipeline infrastructure written in the Java programming language, which marshals data input to and output from MATLAB applications that are executed as external processes. The pipeline modules, which underwent continuous development and refinement even after data started arriving, employ several analytic techniques, many developed for the Kepler Project. Because of the large number of targets, the large amount of data per target and the complexity of the pipeline algorithms, the processing demands are daunting. Some pipeline modules require days to weeks to process all of their targets, even when run on NASA's 128-node Pleiades supercomputer. The software developers are still seeking ways to increase the throughput. To date, the Kepler project has discovered more than 4000 planetary candidates, of which more than 1000 have been independently confirmed or validated to be exoplanets. Funding for this mission is provided by NASAs Science Mission Directorate.

  12. Tropospheric and total ozone columns over Paris (France measured using medium-resolution ground-based solar-absorption Fourier-transform infrared spectroscopy

    Directory of Open Access Journals (Sweden)

    C. Viatte

    2011-10-01

    Full Text Available Ground-based Fourier-transform infrared (FTIR solar absorption spectroscopy is a powerful remote sensing technique providing information on the vertical distribution of various atmospheric constituents. This work presents the first evaluation of a mid-resolution ground-based FTIR to measure tropospheric ozone, independently of stratospheric ozone. This is demonstrated using a new atmospheric observatory (named OASIS for "Observations of the Atmosphere by Solar absorption Infrared Spectroscopy", installed in Créteil (France. The capacity of the technique to separate stratospheric and tropospheric ozone is demonstrated. Daily mean tropospheric ozone columns derived from the Infrared Atmospheric Sounding Interferometer (IASI and from OASIS measurements are compared for summer 2009 and a good agreement of −5.6 (±16.1 % is observed. Also, a qualitative comparison between in-situ surface ozone measurements and OASIS data reveals OASIS's capacity to monitor seasonal tropospheric ozone variations, as well as ozone pollution episodes in summer 2009 around Paris. Two extreme pollution events are identified (on the 1 July and 6 August 2009 for which ozone partial columns from OASIS and predictions from a regional air-quality model (CHIMERE are compared following strict criteria of temporal and spatial coincidence. An average bias of 0.2%, a mean square error deviation of 7.6%, and a correlation coefficient of 0.91 is found between CHIMERE and OASIS, demonstrating the potential of a mid-resolution FTIR instrument in ground-based solar absorption geometry for tropospheric ozone monitoring.

  13. Multi-scale feature learning on pixels and super-pixels for seminal vesicles MRI segmentation

    Science.gov (United States)

    Gao, Qinquan; Asthana, Akshay; Tong, Tong; Rueckert, Daniel; Edwards, Philip "Eddie"

    2014-03-01

    We propose a learning-based approach to segment the seminal vesicles (SV) via random forest classifiers. The proposed discriminative approach relies on the decision forest using high-dimensional multi-scale context-aware spatial, textual and descriptor-based features at both pixel and super-pixel level. After affine transformation to a template space, the relevant high-dimensional multi-scale features are extracted and random forest classifiers are learned based on the masked region of the seminal vesicles from the most similar atlases. Using these classifiers, an intermediate probabilistic segmentation is obtained for the test images. Then, a graph-cut based refinement is applied to this intermediate probabilistic representation of each voxel to get the final segmentation. We apply this approach to segment the seminal vesicles from 30 MRI T2 training images of the prostate, which presents a particularly challenging segmentation task. The results show that the multi-scale approach and the augmentation of the pixel based features with the super-pixel based features enhances the discriminative power of the learnt classifier which leads to a better quality segmentation in some very difficult cases. The results are compared to the radiologist labeled ground truth using leave-one-out cross-validation. Overall, the Dice metric of 0:7249 and Hausdorff surface distance of 7:0803 mm are achieved for this difficult task.

  14. Automated Detection of Contaminated Radar Image Pixels in Mountain Areas

    Institute of Scientific and Technical Information of China (English)

    LIU Liping; Qin XU; Pengfei ZHANG; Shun LIU

    2008-01-01

    In mountain areas,radar observations are often contaminated(1)by echoes from high-speed moving vehicles and(2)by point-wise ground clutter under either normal propagation(NP)or anomalous propa-gation(AP)conditions.Level II data are collected from KMTX(Salt Lake City,Utah)radar to analyze these two types of contamination in the mountain area around the Great Salt Lake.Human experts provide the"ground truth"for possible contamination of either type on each individual pixel.Common features are then extracted for contaminated pixels of each type.For example,pixels contaminated by echoes from high-speed moving vehicles are characterized by large radial velocity and spectrum width.Echoes from a moving train tend to have larger velocity and reflectivity but smaller spectrum width than those from moving vehicles on highways.These contaminated pixels are only seen in areas of large terrain gradient(in the radial direction along the radar beam).The same is true for the second type of contamination-point-wise ground clutters.Six quality control(QC)parameters are selected to quantify the extracted features.Histograms are computed for each QC parameter and grouped for contaminated pixels of each type and also for non-contaminated pixels.Based on the computed histograms,a fuzzy logical algorithm is developed for automated detection of contaminated pixels.The algorithm is tested with KMTX radar data under different(clear and rainy)weather conditions.

  15. Performance limits of a single photon counting pixel system

    Science.gov (United States)

    Chmeissani, M.; Mikulec, B.

    2001-03-01

    X-ray imaging using hybrid pixel detectors in single photon counting mode is a relatively recent and exciting development. The photon counting mode implies that each pixel has a threshold in energy above which a hit is recorded. Sharing of charge between adjacent pixels would therefore lead to a loss of registered hits and for medical imaging applications to a higher patient dose. This explains why the demand for high spatial resolution and consequently small pixel sizes (<100 μm) motivates the Medipix2 collaboration to study the effects of charge sharing between pixels on system performance. Two different simulation codes are used to simulate the energy loss inside the detector and the charge transport towards the pixel electrodes. The largest contribution to the lateral spreading of charge comes from diffusion and can result in a considerable loss of detection efficiency in photon counting systems for small pixel sizes. The Medipix2 collaboration consists of groups from Barcelona, Cagliari, CEA/Leti DEIN, CERN, Freiburg, Glasgow, Mitthögskolan, Napoli, NIKHEF, MRC lab Cambridge, Pisa, Prague and Sassari.

  16. Radiation hardness studies of silicon pixel detectors

    CERN Document Server

    Lari, T

    2006-01-01

    At the LHC silicon vertex detectors will be exposed to hadron fluences of the order of . In order to study the effects of radiation damage on the performances of the ATLAS Pixel Vertex Detector, several full-size detector modules were irradiated to a fluence of and tested in a beam at CERN. After irradiation only a modest degradation of the detector performances is observed. At the operating ATLAS bias voltage of 600 V the average signal is still 80% of the pre-irradiation value, the spatial resolution is and the detection efficiency is 98.2%. The LHC luminosity upgrade will increase the radiation hardness requirements by a factor of 10 and will require the development of new ultra-radiation hard vertex detectors. A detailed simulation of silicon pixel detectors irradiated to very high fluence is presented and used to study the possibility to use silicon pixel detectors at the LHC after the luminosity upgrade. The charge collection properties and the detector response were computed for different silicon mater...

  17. Bump bonding of pixel systems

    Energy Technology Data Exchange (ETDEWEB)

    Lozano, M. E-mail: manuel.lozano@cnm.es; Cabruja, E.; Collado, A.; Santander, J.; Ullan, M

    2001-11-01

    A pixel detector consists of an array of radiation sensing elements which is connected to an electronic read-out unit. Many different ways of making this connection between these two different devices are currently being used or considered to be used in the next future. Bonding techniques such as flip chip technology can present real advantages because they allow very fine pitch and a high number of I/Os. This paper presents a review of the different flip chip technologies available and their suitability for manufacturing pixel detectors. The particular problems concerning testing of pixel detectors and thermal issues related to them are pointed out.

  18. Bump bonding of pixel systems

    CERN Document Server

    Lozano, M; Collado, A; Santander, J; Ullán, M

    2001-01-01

    A pixel detector consists of an array of radiation sensing elements which is connected to an electronic read-out unit. Many different ways of making this connection between these two different devices are currently being used or considered to be used in the next future. Bonding techniques such as flip chip technology can present real advantages because they allow very fine pitch and a high number of I/Os. This paper presents a review of the different flip chip technologies available and their suitability for manufacturing pixel detectors. The particular problems concerning testing of pixel detectors and thermal issues related to them are pointed out.

  19. CMS Barrel Pixel Detector Overview

    CERN Document Server

    Kästli, H C; Erdmann, W; Gabathuler, K; Hörmann, C; Horisberger, Roland Paul; König, S; Kotlinski, D; Meier, B; Robmann, P; Rohe, T; Streuli, S

    2007-01-01

    The pixel detector is the innermost tracking device of the CMS experiment at the LHC. It is built from two independent sub devices, the pixel barrel and the end disks. The barrel consists of three concentric layers around the beam pipe with mean radii of 4.4, 7.3 and 10.2 cm. There are two end disks on each side of the interaction point at 34.5 cm and 46.5 cm. This article gives an overview of the pixel barrel detector, its mechanical support structure, electronics components, services and its expected performance.

  20. Performance of silicon pixel detectors at small track incidence angles

    CERN Document Server

    Viel, Simon; The ATLAS collaboration

    2015-01-01

    In order to enable the ATLAS experiment to successfully track charged particles produced in high-energy collisions at the High-Luminosity Large Hadron Collider, the current ATLAS Inner Detector will be replaced by the Inner Tracker (ITk), entirely composed of silicon pixel and strip detectors. An extension of the tracking coverage of ITk to very forward pseudorapidity values is proposed, using pixel modules placed in a long cylindrical layer around the beam pipe. The measurement of long pixel clusters, detected when charged particles cross the silicon sensor at small incidence angles, has potential to significantly improve the tracking efficiency, fake track rejection, and resolution of ITk in the very forward region. The performance of state-of-the-art pixel modules at small track incidence angles is studied using test beam data collected at SLAC and CERN, as well as simulated data.

  1. Two-dimensional pixel array image sensor for protein crystallography

    Energy Technology Data Exchange (ETDEWEB)

    Beuville, E.; Beche, J.-F.; Cork, C. [and others

    1996-07-01

    A 2D pixel array image sensor module has been designed for time resolved Protein Crystallography. This smart pixels detector significantly enhances time resolved Laue Protein crystallography by two to three orders of magnitude compared to existing sensors like films or phosphor screens coupled to CCDs. The resolution in time and dynamic range of this type of detector will allow one to study the evolution of structural changes that occur within the protein as a function of time. This detector will also considerably accelerate data collection in static Laue or monochromatic crystallography and make better use of the intense beam delivered by synchrotron light sources. The event driven pixel array detectors, based on the column Architecture, can provide multiparameter information (energy discrimination, time), with sparse and frameless readout without significant dead time. The prototype module consists of a 16x16 pixel diode array bump-bonded to the integrated circuit. The detection area is 150x150 square microns.

  2. Mapping growing stock at 1-km spatial resolution for Spanish forest areas from ground forest inventory data and GLAS canopy height

    Science.gov (United States)

    Sánchez-Ruiz, S.; Chiesi, M.; Maselli, F.; Gilabert, M. A.

    2016-10-01

    National forest inventories provide measurements of forest variables (e.g. growing stock) that can be used for the estimation of above ground biomass (AGB). Mapping growing stock brings knowledge about spatial distribution and temporal dynamics of ABG, which is necessary for carbon cycle analysis. Several studies have been conducted on the integration of ground and optical remote sensing data to map forest biomass over Europe. Nevertheless, more direct information on forest biomass could be obtained by LiDAR techniques, which directly assess vertical forest structure by measuring the distance between the sensor and the scattering elements located inside the canopy volume. Thus, global 1-km maps of forest canopy height have been recently obtained from the Geoscience Laser Altimeter System (GLAS). The current study aims to produce a forest growing stock map in Spain. Five different forest type areas were identified in three provinces along a North - South gradient accounting for different ecosystems and climatic conditions. Growing stock ground data from the Third Spanish National Forest Inventory were assigned to each forest type and aggregated to 1-km spatial resolution. GLAS-derived canopy height was extracted for the locations of selected ground data. A relationship between inventory growing stock and satellite canopy height was found for each class. The obtained relationships were then extended all over Spain. The accuracy of the resulting growing stock map was assessed at province level against the Third Spanish National Forest Inventory growing stock estimations (R = 0.85, RMSE = 21 m3 ha-1).

  3. High-resolution electrical resistivity tomography applied to patterned ground, Wedel Jarlsberg Land, south-west Spitsbergen

    Directory of Open Access Journals (Sweden)

    Marek Kasprzak

    2015-06-01

    Full Text Available This article presents results of two-dimensional electrical resistivity tomography (ERT applied to three types of patterned ground in Wedel-Jarlsberg Land (Svalbard, carried out in late July 2012. The structures investigated include sorted circles, non-sorted polygons and a net with sorted coarser material. ERT was used to recognize the internal ground structure, the shape of permafrost table below the active layer and the geometric relationships between permafrost, ground layering and surface patterns. Results of inversion modelling indicate that the permafrost table occurs at a depth of 0.5–1 m in a mountain valley and 1–2.5 m on raised marine terraces. The permafrost table was nearly planar beneath non-sorted deposits and wavy beneath sorted materials. The mutual relationships between the permafrost table and the shape of a stone circle are different from those typically presented in literature. Ground structure beneath the net with sorted coarser materials is complex as implied in convective models. In non-sorted polygons, the imaging failed to reveal vertical structures between them.

  4. The pixel tracking telescope at the Fermilab Test Beam Facility

    Energy Technology Data Exchange (ETDEWEB)

    Kwan, Simon; Lei, CM [Fermi National Accelerator Laboratory, Batavia, IL (United States); Menasce, Dario; Moroni, Luigi; Ngadiuba, Jennifer [Istituto Nazionale di Fisica Nucleare, Sezione di Milano Bicocca, and Università degli Studi di Milano Bicocca, Piazza della Scienza 3, 20126 Milano (Italy); Prosser, Alan; Rivera, Ryan [Fermi National Accelerator Laboratory, Batavia, IL (United States); Terzo, Stefano [Istituto Nazionale di Fisica Nucleare, Sezione di Milano Bicocca, and Università degli Studi di Milano Bicocca, Piazza della Scienza 3, 20126 Milano (Italy); Turqueti, Marcos [Fermi National Accelerator Laboratory, Batavia, IL (United States); Uplegger, Lorenzo, E-mail: uplegger@fnal.gov [Fermi National Accelerator Laboratory, Batavia, IL (United States); Vigani, Luigi; Dinardo, Mauro E. [Fermi National Accelerator Laboratory, Batavia, IL (United States)

    2016-03-01

    An all silicon pixel telescope has been assembled and used at the Fermilab Test Beam Facility (FTBF) since 2009 to provide precise tracking information for different test beam experiments with a wide range of Detectors Under Test (DUTs) requiring high resolution measurement of the track impact point. The telescope is based on CMS pixel modules left over from the CMS forward pixel production. Eight planes are arranged to achieve a resolution of less than 8 μm on the 120 GeV proton beam transverse coordinate at the DUT position. In order to achieve such resolution with 100×150 μm{sup 2} pixel cells, the planes were tilted to 25 degrees to maximize charge sharing between pixels. Crucial for obtaining this performance is the alignment software, called Monicelli, specifically designed and optimized for this system. This paper will describe the telescope hardware, the data acquisition system and the alignment software constituting this particle tracking system for test beam users.

  5. Using Moderate-Resolution Temporal NDVI Profiles for High-Resolution Crop Mapping in Years of Absent Ground Reference Data: A Case Study of Bole and Manas Counties in Xinjiang, China

    Directory of Open Access Journals (Sweden)

    Pengyu Hao

    2016-05-01

    Full Text Available Most methods used for crop classification rely on the ground-reference data of the same year, which leads to considerable financial and labor cost. In this study, we presented a method that can avoid the requirements of a large number of ground-reference data in the classification year. Firstly, we extracted the Normalized Difference Vegetation Index (NDVI time series profiles of the dominant crops from MODIS data using the historical ground-reference data in multiple years (2006, 2007, 2009 and 2010. Artificial Antibody Network (ABNet was then employed to build reference NDVI time series for each crop based on the historical NDVI profiles. Afterwards, images of Landsat and HJ were combined to obtain 30 m image time series with 15-day acquisition frequency in 2011. Next, the reference NDVI time series were transformed to Landsat/HJ NDVI time series using their linear model. Finally, the transformed reference NDVI profiles were used to identify the crop types in 2011 at 30 m spatial resolution. The result showed that the dominant crops could be identified with overall accuracy of 87.13% and 83.48% in Bole and Manas, respectively. In addition, the reference NDVI profiles generated from multiple years could achieve better classification accuracy than that from single year (such as only 2007. This is mainly because the reference knowledge from multiple years contains more growing conditions of the same crop. Generally, this approach showed potential to identify crops without using large number of ground-reference data at 30 m resolution.

  6. Smart pixel imaging with computational-imaging arrays

    Science.gov (United States)

    Fernandez-Cull, Christy; Tyrrell, Brian M.; D'Onofrio, Richard; Bolstad, Andrew; Lin, Joseph; Little, Jeffrey W.; Blackwell, Megan; Renzi, Matthew; Kelly, Mike

    2014-07-01

    Smart pixel imaging with computational-imaging arrays (SPICA) transfers image plane coding typically realized in the optical architecture to the digital domain of the focal plane array, thereby minimizing signal-to-noise losses associated with static filters or apertures and inherent diffraction concerns. MIT Lincoln Laboratory has been developing digitalpixel focal plane array (DFPA) devices for many years. In this work, we leverage legacy designs modified with new features to realize a computational imaging array (CIA) with advanced pixel-processing capabilities. We briefly review the use of DFPAs for on-chip background removal and image plane filtering. We focus on two digital readout integrated circuits (DROICS) as CIAs for two-dimensional (2D) transient target tracking and three-dimensional (3D) transient target estimation using per-pixel coded-apertures or flutter shutters. This paper describes two DROICs - a SWIR pixelprocessing imager (SWIR-PPI) and a Visible CIA (VISCIA). SWIR-PPI is a DROIC with a 1 kHz global frame rate with a maximum per-pixel shuttering rate of 100 MHz, such that each pixel can be modulated by a time-varying, pseudorandom, and duo-binary signal (+1,-1,0). Combining per-pixel time-domain coding and processing enables 3D (x,y,t) target estimation with limited loss of spatial resolution. We evaluate structured and pseudo-random encoding strategies and employ linear inversion and non-linear inversion using total-variation minimization to estimate a 3D data cube from a single 2D temporally-encoded measurement. The VISCIA DROIC, while low-resolution, has a 6 kHz global frame rate and simultaneously encodes eight periodic or aperiodic transient target signatures at a maximum rate of 50 MHz using eight 8-bit counters. By transferring pixel-based image plane coding to the DROIC and utilizing sophisticated processing, our CIAs enable on-chip temporal super-resolution.

  7. Optical Cloud Pixel Recovery via Machine Learning

    Directory of Open Access Journals (Sweden)

    Subrina Tahsin

    2017-05-01

    Full Text Available Remote sensing derived Normalized Difference Vegetation Index (NDVI is a widely used index to monitor vegetation and land use change. NDVI can be retrieved from publicly available data repositories of optical sensors such as Landsat, Moderate Resolution Imaging Spectro-radiometer (MODIS and several commercial satellites. Studies that are heavily dependent on optical sensors are subject to data loss due to cloud coverage. Specifically, cloud contamination is a hindrance to long-term environmental assessment when using information from satellite imagery retrieved from visible and infrared spectral ranges. Landsat has an ongoing high-resolution NDVI record starting from 1984. Unfortunately, this long time series NDVI data suffers from the cloud contamination issue. Though both simple and complex computational methods for data interpolation have been applied to recover cloudy data, all the techniques have limitations. In this paper, a novel Optical Cloud Pixel Recovery (OCPR method is proposed to repair cloudy pixels from the time-space-spectrum continuum using a Random Forest (RF trained and tested with multi-parameter hydrologic data. The RF-based OCPR model is compared with a linear regression model to demonstrate the capability of OCPR. A case study in Apalachicola Bay is presented to evaluate the performance of OCPR to repair cloudy NDVI reflectance. The RF-based OCPR method achieves a root mean squared error of 0.016 between predicted and observed NDVI reflectance values. The linear regression model achieves a root mean squared error of 0.126. Our findings suggest that the RF-based OCPR method is effective to repair cloudy pixels and provides continuous and quantitatively reliable imagery for long-term environmental analysis.

  8. Online calibrations and performance of the ATLAS Pixel Detector

    CERN Document Server

    Keil, M; The ATLAS collaboration

    2010-01-01

    The ATLAS Pixel Detector is the innermost detector of the ATLAS experiment at the Large Hadron Collider at CERN. It consists of 1744 silicon sensors equipped with approximately 80 M electronic channels, providing typically three measurement points with high resolution for particles emerging from the beam-interaction region, thus allowing measuring particle tracks and secondary vertices with very high precision. The readout system of the Pixel Detector is based on a bi-directional optical data transmission system between the detector and the data acquisition system with an individual link for each of the 1744 modules. Signal conversion components are located on both ends, approximately 80 m apart. The talk will give an overview of the calibration and performance of both the detector and its optical readout. The most basic parameter to be tuned and calibrated for the detector electronics is the readout threshold of the individual pixel channels. These need to be carefully tuned to optimise position resolution a...

  9. Semi-Automatic Selection of Ground Control Points for High Resolution Remote Sensing Data in Urban Areas

    Directory of Open Access Journals (Sweden)

    Gulbe Linda

    2016-12-01

    Full Text Available Geometrical accuracy of remote sensing data often is ensured by geometrical transforms based on Ground Control Points (GCPs. Manual selection of GCP is a time-consuming process, which requires some sort of automation. Therefore, the aim of this study is to present and evaluate methodology for easier, semi-automatic selection of ground control points for urban areas. Custom line scanning algorithm was implemented and applied to data in order to extract potential GCPs for an image analyst. The proposed method was tested for classical orthorectification and special object polygon transform. Results are convincing and show that in the test case semi-automatic methodology is able to correct locations of 70 % (thermal data – 80 % (orthophoto images of buildings. Geometrical transform for subimages of approximately 3 hectares with approximately 12 automatically found GCPs resulted in RSME approximately 1 meter with standard deviation of 1.2 meters.

  10. Upscaling In Situ Soil Moisture Observations to Pixel Averages with Spatio-Temporal Geostatistics

    Directory of Open Access Journals (Sweden)

    Jianghao Wang

    2015-09-01

    Full Text Available Validation of satellite-based soil moisture products is necessary to provide users with an assessment of their accuracy and reliability and to ensure quality of information. A key step in the validation process is to upscale point-scale, ground-based soil moisture observations to satellite-scale pixel averages. When soil moisture shows high spatial heterogeneity within pixels, a strategy which captures the spatial characteristics is essential for the upscaling process. In addition, temporal variation in soil moisture must be taken into account when measurement times of ground-based and satellite-based observations are not the same. We applied spatio-temporal regression block kriging (STRBK to upscale in situ soil moisture observations collected as time series at multiple locations to pixel averages. STRBK incorporates auxiliary information such as maps of vegetation and land surface temperature to improve predictions and exploits the spatio-temporal correlation structure of the point-scale soil moisture observations. In addition, STRBK also quantifies the uncertainty associated with the upscaled soil moisture which allows bias detection and significance testing of satellite-based soil moisture products. The approach is illustrated with a real-world application for upscaling in situ soil moisture observations for validating the Polarimetric L-band Multi-beam Radiometer (PLMR retrieved soil moisture product in the Heihe Water Allied Telemetry Experimental Research experiment (HiWATER. The results show that STRBK yields upscaled soil moisture predictions that are sufficiently accurate for validation purposes. Comparison of the upscaled predictions with PLMR soil moisture observations shows that the root-mean-squared error of the PLMR soil moisture product is about 0.03 m3·m−3 and can be used as a high-resolution soil moisture product for watershed-scale soil moisture monitoring.

  11. Efficient single pixel imaging in Fourier space

    Science.gov (United States)

    Bian, Liheng; Suo, Jinli; Hu, Xuemei; Chen, Feng; Dai, Qionghai

    2016-08-01

    Single pixel imaging (SPI) is a novel technique capturing 2D images using a bucket detector with a high signal-to-noise ratio, wide spectrum range and low cost. Conventional SPI projects random illumination patterns to randomly and uniformly sample the entire scene’s information. Determined by Nyquist sampling theory, SPI needs either numerous projections or high computation cost to reconstruct the target scene, especially for high-resolution cases. To address this issue, we propose an efficient single pixel imaging technique (eSPI), which instead projects sinusoidal patterns for importance sampling of the target scene’s spatial spectrum in Fourier space. Specifically, utilizing the centrosymmetric conjugation and sparsity priors of natural images’ spatial spectra, eSPI sequentially projects two \\tfrac{π }{2}-phase-shifted sinusoidal patterns to obtain each Fourier coefficient in the most informative spatial frequency bands. eSPI can reduce requisite patterns by two orders of magnitude compared to conventional SPI, which helps a lot for fast and high-resolution SPI.

  12. X-ray micro-beam characterization of a small pixel spectroscopic CdTe detector

    Science.gov (United States)

    Veale, M. C.; Bell, S. J.; Seller, P.; Wilson, M. D.; Kachkanov, V.

    2012-07-01

    A small pixel, spectroscopic, CdTe detector has been developed at the Rutherford Appleton Laboratory (RAL) for X-ray imaging applications. The detector consists of 80 × 80 pixels on a 250 μm pitch with 50 μm inter-pixel spacing. Measurements with an 241Am γ-source demonstrated that 96% of all pixels have a FWHM of better than 1 keV while the majority of the remaining pixels have FWHM of less than 4 keV. Using the Diamond Light Source synchrotron, a 10 μm collimated beam of monochromatic 20 keV X-rays has been used to map the spatial variation in the detector response and the effects of charge sharing corrections on detector efficiency and resolution. The mapping measurements revealed the presence of inclusions in the detector and quantified their effect on the spectroscopic resolution of pixels.

  13. Detection of a large sample of Gamma Dor stars from Kepler space photometry and high-resolution ground-based spectroscopy

    CERN Document Server

    Tkachenko, A; Yakushechkin, A; Debosscher, J; Degroote, P; Bloemen, S; Papics, P I; de Vries, B L; Lombaert, R; Hrudkova, M; Fremat, Y; Raskin, G; Van Winckel, H

    2013-01-01

    The space-missions MOST, CoRoT, and Kepler deliver a huge amount of high-quality photometric data suitable to study numerous pulsating stars. Our ultimate goal is a detection and analysis of an extended sample of Gamma Dor-type pulsating stars with the aim to search for observational evidence of non-uniform period spacings and rotational splittings of gravity modes in main-sequence stars typically twice as massive as the Sun. We applied an automated supervised photometric classification method to select a sample of 69 Gamma Doradus candidate stars. We used an advanced method to extract the Kepler light curves from the pixel data information using custom masks. For 36 of the stars, we obtained high-resolution spectroscopy with the HERMES spectrograph installed at the Mercator telescope. We find that all stars for which spectroscopic estimates of Teff and logg are available fall into the region of the HR diagram where the Gamma Dor and Delta Sct instability strips overlap. The stars cluster in a 700 K window in...

  14. Socialising the pixel: The use of citizen science in land use classification and its potential uncertainties

    NARCIS (Netherlands)

    Visser, T.

    2015-01-01

    When making an land use map of an area with the use of remote sensing data, additional data from the ground is needed for this area, the so called ‘ground truth’. By combining the datasets a a land use classification can be done, relating a pixel with the actual situation on the ground. The collect

  15. Evaluation of Relative Geometric Accuracy of Terrasar-X by Pixel Matching Methodology

    Science.gov (United States)

    Nonaka, T.; Asaka, T.; Iwashita, K.

    2016-06-01

    Recently, high-resolution commercial SAR satellites with several meters of resolutions are widely utilized for various applications and disaster monitoring is one of the commonly applied areas. The information about the flooding situation and ground displacement was rapidly announced to the public after the Great East Japan Earthquake 2011. One of the studies reported the displacement in Tohoku region by the pixel matching methodology using both pre- and post- event TerraSAR-X data, and the validated accuracy was about 30 cm at the GEONET reference points. In order to discuss the spatial distribution of the displacement, we need to evaluate the relative accuracy of the displacement in addition to the absolute accuracy. In the previous studies, our study team evaluated the absolute 2D geo-location accuracy of the TerraSAR-X ortho-rectified EEC product for both flat and mountain areas. Therefore, the purpose of the current study was to evaluate the spatial and temporal relative geo-location accuracies of the product by considering the displacement of the fixed point as the relative geo-location accuracy. Firstly, by utilizing TerraSAR-X StripMap dataset, the pixel matching method for estimating the displacement with sub-pixel level was developed. Secondly, the validity of the method was confirmed by comparing with GEONET data. We confirmed that the accuracy of the displacement for X and Y direction was in agreement with the previous studies. Subsequently, the methodology was applied to 20 pairs of data set for areas of Tokyo Ota-ku and Kawasaki-shi, and the displacement of each pair was evaluated. It was revealed that the time series displacement rate had the seasonal trend and seemed to be related to atmospheric delay.

  16. High resolution infrared synchrotron study of CH2D81Br: ground state constants and analysis of the ν5, ν6 and ν9 fundamentals

    Science.gov (United States)

    Baldacci, A.; Stoppa, P.; Visinoni, R.; Wugt Larsen, R.

    2012-09-01

    The high resolution infrared absorption spectrum of CH2D81Br has been recorded by Fourier transform spectroscopy in the range 550-1075 cm-1, with an unapodized resolution of 0.0025 cm-1, employing a synchrotron radiation source. This spectral region is characterized by the ν6 (593.872 cm-1), ν5 (768.710 cm-1) and ν9 (930.295 cm-1) fundamental bands. The ground state constants up to sextic centrifugal distortion terms have been obtained for the first time by ground-state combination differences from the three bands and subsequently employed for the evaluation of the excited state parameters. Watson's A-reduced Hamiltonian in the Ir representation has been used in the calculations. The ν 6 = 1 level is essentially free from perturbation whereas the ν 5 = 1 and ν 9 = 1 states are mutually interacting through a-type Coriolis coupling. Accurate spectroscopic parameters of the three excited vibrational states and a high-order coupling constant which takes into account the interaction between ν5 and ν9 have been determined.

  17. Generation of remotely sensed reference data using low altitude, high spatial resolution hyperspectral imagery

    Science.gov (United States)

    Williams, McKay D.; van Aardt, Jan; Kerekes, John P.

    2016-05-01

    Exploitation of imaging spectroscopy (hyperspectral) data using classification and spectral unmixing algorithms is a major research area in remote sensing, with reference data required to assess algorithm performance. However, we are limited by our inability to generate rapid, accurate, and consistent reference data, thus making quantitative algorithm analysis difficult. As a result, many investigators present either limited quantitative results, use synthetic imagery, or provide qualitative results using real imagery. Existing reference data typically classify large swaths of imagery pixel-by-pixel, per cover type. While this type of mapping provides a first order understanding of scene composition, it is not detailed enough to include complexities such as mixed pixels, intra-end-member variability, and scene anomalies. The creation of more detailed ground reference data based on field work, on the other hand, is complicated by the spatial scale of common hyperspectral data sets. This research presents a solution to this challenge via classification of low altitude, high spatial resolution (1m GSD) National Ecological Observatory Network (NEON) hyperspectral imagery, on a pixel-by-pixel basis, to produce sub-pixel reference data for high altitude, lower spatial resolution (15m GSD) AVIRIS imagery. This classification is performed using traditional classification techniques, augmented by (0.3m GSD) NEON RGB data. This paper provides a methodology for generating large scale, sub-pixel reference data for AVIRIS imagery using NEON imagery. It also addresses challenges related to the fusion of multiple remote sensing modalities (e.g., different sensors, sensor look angles, spatial registration, varying scene illumination, etc.). A new algorithm for spatial registration of hyperspectral imagery with disparate resolutions is presented. Several versions of reference data results are compared to each other and to direct spectral unmixing of AVIRIS data. Initial results are

  18. Charge induction in semiconductor detectors with pixellated structure

    NARCIS (Netherlands)

    Samedov, Victor V.

    2007-01-01

    Considerable interest is now being attracted to the next generation of compound semiconductor detectors with pixellated structure in application to x-ray and gamma-astronomy, nuclear spectroscopy and nuclear medicine. The spatial resolution of this type of detectors is mainly determined by the proce

  19. An empirically grounded agent based model for modeling directs, conflict detection and resolution operations in Air Traffic Management

    CERN Document Server

    Bongiorno, C; Mantegna, Rosario N

    2016-01-01

    We present an agent based model of the Air Traffic Management socio-technical complex system that aims at modeling the interactions between aircrafts and air traffic controllers at a tactical level. The core of the model is given by the conflict detection and resolution module and by the directs module. Directs are flight shortcuts that are given by air controllers to speed up the passage of an aircraft within a certain airspace and therefore to facilitate airline operations. Conflicts resolution between flight trajectories can arise during the en-route phase of each flight due to both not detailed flight trajectory planning or unforeseen events that perturb the planned flight plan. Our model performs a local conflict detection and resolution procedure. Once a flight trajectory has been made conflict-free, the model searches for possible improvements of the system efficiency by issuing directs. We give an example of model calibration based on real data. We then provide an illustration of the capability of our...

  20. Tropospheric and total ozone columns over Paris (France measured using medium-resolution ground-based solar-absorption Fourier-transform infrared spectroscopy

    Directory of Open Access Journals (Sweden)

    C. Viatte

    2011-05-01

    Full Text Available Ground-based Fourier-transform infrared (FTIR solar absorption spectroscopy is a powerful remote sensing technique providing information on the vertical distribution of various atmospheric constituents. This work presents the first evaluation of a mid-resolution ground-based FTIR to measure tropospheric ozone, independently of stratospheric ozone. This is demonstrated using a new atmospheric observatory (named OASIS for "Observations of the Atmosphere by Solar absorption Infrared Spectroscopy", installed in Créteil (France. Indeed, the information content of OASIS ozone retrievals is clearly sufficient to monitor separately tropospheric (from the surface up to 8 km and stratospheric ozone. Daily mean tropospheric ozone columns derived from the Infrared Atmospheric Sounding Interferometer (IASI and from OASIS measurements have been compared for summer 2009 and a good agreement of −5.6 (±16.1 % is observed. Also, a qualitative comparison between in-situ surface ozone measurements and OASIS data clearly shows OASIS's capacity to monitor seasonal tropospheric ozone variations, as well as ozone pollution episodes in summer 2009 around Paris. Two extreme pollution events were identified (on the 1 July and 6 August 2009 for which ozone partial columns from OASIS and predictions from a regional air-quality model (CHIMERE were compared by respecting temporal and spatial coincidence criteria. Quantitatively, an average bias of 0.2 %, a mean square error deviation of 7.6 %, and a correlation coefficient of 0.91 was found between CHIMERE and OASIS. This demonstrates that a mid-resolution FTIR instrument in ground-based solar absorption geometry is a promising technique for monitoring tropospheric ozone.

  1. CMS Forward Pixel Upgrade Electronics and System Testing

    CERN Document Server

    Weber, Hannsjorg Artur

    2016-01-01

    This note discusses results of electronics and system testing of the CMS forward pixel (FPIX) detector upgrade for Phase 1. The FPIX detector is comprised of four stand-alone half cylinders, each of which contains frontend readout electronic boards, power regulators, cables and fibers in addition to the pixel modules. All of the components undergo rigorous testing and quality assurance before assembly into the half cylinders. Afterwards, we perform full system tests on the completely assembled half cylinders, including calibrations at final operating temperatures, characterization of the realistic readout chain, and system grounding and noise studies. The results from all these tests are discussed.

  2. 3D electronics for hybrid pixel detectors – TWEPP-09

    CERN Document Server

    Godiot, S; Chantepie, B; Clémens, J C; Fei, R; Fleury, J; Fougeron, D; Garcia-Sciveres, M; Hemperek, T; Karagounis, M; Krueger, H; Mekkaoui, A; Pangaud, P; Rozanov, A; Wermes, N

    2009-01-01

    Future hybrid pixel detectors are asking for smaller pixels in order to improve spatial resolution and to deal with an increasing counting rate. Facing these requirements is foreseen to be done by microelectronics technology shrinking. However, this straightforward approach presents some disadvantages in term of performances and cost. New 3D technologies offer an alternative way with the advantage of technology mixing. For the upgrade of ATLAS pixel detector, a 3D conception of the read-out chip appeared as an interesting solution. Splitting the pixel functionalities into two separate levels will reduce pixel size and open the opportunity to take benefit of technology's mixing. Based on a previous prototype of the read-out chip FE-I4 (IBM 130nm), this paper presents the design of a hybrid pixel read-out chip using threedimensional Tezzaron-Chartered technology. In order to disentangle effects due to Chartered 130nm technology from effects involved by 3D architecture, a first translation of FEI4 prototype had ...

  3. Challenges of small-pixel infrared detectors: a review

    Science.gov (United States)

    Rogalski, A.; Martyniuk, P.; Kopytko, M.

    2016-04-01

    In the last two decades, several new concepts for improving the performance of infrared detectors have been proposed. These new concepts particularly address the drive towards the so-called high operating temperature focal plane arrays (FPAs), aiming to increase detector operating temperatures, and as a consequence reduce the cost of infrared systems. In imaging systems with the above megapixel formats, pixel dimension plays a crucial role in determining critical system attributes such as system size, weight and power consumption (SWaP). The advent of smaller pixels has also resulted in the superior spatial and temperature resolution of these systems. Optimum pixel dimensions are limited by diffraction effects from the aperture, and are in turn wavelength-dependent. In this paper, the key challenges in realizing optimum pixel dimensions in FPA design including dark current, pixel hybridization, pixel delineation, and unit cell readout capacity are outlined to achieve a sufficiently adequate modulation transfer function for the ultra-small pitches involved. Both photon and thermal detectors have been considered. Concerning infrared photon detectors, the trade-offs between two types of competing technology—HgCdTe material systems and III-V materials (mainly barrier detectors)—have been investigated.

  4. Increased space-bandwidth product in pixel super-resolved lensfree on-chip microscopy

    Science.gov (United States)

    Greenbaum, Alon; Luo, Wei; Khademhosseinieh, Bahar; Su, Ting-Wei; Coskun, Ahmet F.; Ozcan, Aydogan

    2013-04-01

    Pixel-size limitation of lensfree on-chip microscopy can be circumvented by utilizing pixel-super-resolution techniques to synthesize a smaller effective pixel, improving the resolution. Here we report that by using the two-dimensional pixel-function of an image sensor-array as an input to lensfree image reconstruction, pixel-super-resolution can improve the numerical aperture of the reconstructed image by ~3 fold compared to a raw lensfree image. This improvement was confirmed using two different sensor-arrays that significantly vary in their pixel-sizes, circuit architectures and digital/optical readout mechanisms, empirically pointing to roughly the same space-bandwidth improvement factor regardless of the sensor-array employed in our set-up. Furthermore, such a pixel-count increase also renders our on-chip microscope into a Giga-pixel imager, where an effective pixel count of ~1.6-2.5 billion can be obtained with different sensors. Finally, using an ultra-violet light-emitting-diode, this platform resolves 225 nm grating lines and can be useful for wide-field on-chip imaging of nano-scale objects, e.g., multi-walled-carbon-nanotubes.

  5. Ground-based remote sensing of O3 by high- and medium-resolution FTIR spectrometers over the Mexico City basin

    Science.gov (United States)

    Plaza-Medina, Eddy F.; Stremme, Wolfgang; Bezanilla, Alejandro; Grutter, Michel; Schneider, Matthias; Hase, Frank; Blumenstock, Thomas

    2017-07-01

    We present atmospheric ozone (O3) profiles measured over central Mexico between November 2012 and February 2014 from two different ground-based FTIR (Fourier transform infrared) solar absorption experiments. The first instrument offers very high-resolution spectra and contributes to NDACC (Network for the Detection of Atmospheric Composition Change). It is located at a mountain observatory about 1700 m above the Mexico City basin. The second instrument has a medium spectral resolution and is located inside Mexico City at a horizontal distance of about 60 km from the mountain observatory. It is documented that the retrieval with the high- and medium-resolution experiments provides O3 variations for four and three independent atmospheric altitude ranges, respectively, and the theoretically estimated errors of these profile data are mostly within 10 %. The good quality of the data is empirically demonstrated above the tropopause by intercomparing the two FTIR O3 data, and for the boundary layer by comparing the Mexico City FTIR O3 data with in situ O3 surface data. Furthermore, we develop a combined boundary layer O3 remote sensing product that uses the retrieval results of both FTIR experiments, and we use theoretical and empirical evaluations to document the improvements that can be achieved by such a combination.

  6. Ground-based remote sensing of O3 by high- and medium-resolution FTIR spectrometers over the Mexico City basin

    Directory of Open Access Journals (Sweden)

    E. F. Plaza-Medina

    2017-07-01

    Full Text Available We present atmospheric ozone (O3 profiles measured over central Mexico between November 2012 and February 2014 from two different ground-based FTIR (Fourier transform infrared solar absorption experiments. The first instrument offers very high-resolution spectra and contributes to NDACC (Network for the Detection of Atmospheric Composition Change. It is located at a mountain observatory about 1700 m above the Mexico City basin. The second instrument has a medium spectral resolution and is located inside Mexico City at a horizontal distance of about 60 km from the mountain observatory. It is documented that the retrieval with the high- and medium-resolution experiments provides O3 variations for four and three independent atmospheric altitude ranges, respectively, and the theoretically estimated errors of these profile data are mostly within 10 %. The good quality of the data is empirically demonstrated above the tropopause by intercomparing the two FTIR O3 data, and for the boundary layer by comparing the Mexico City FTIR O3 data with in situ O3 surface data. Furthermore, we develop a combined boundary layer O3 remote sensing product that uses the retrieval results of both FTIR experiments, and we use theoretical and empirical evaluations to document the improvements that can be achieved by such a combination.

  7. Technical note: Sensitivity of instrumental line shape monitoring for the ground-based high-resolution FTIR spectrometer with respect to different optical attenuators

    Science.gov (United States)

    Sun, Youwen; Palm, Mathias; Weinzierl, Christine; Petri, Christof; Notholt, Justus; Wang, Yuting; Liu, Cheng

    2017-03-01

    The TCCON (Total Carbon Column Observing Network) and most NDACC (Network for Detection of Atmospheric Composition Change) sites assume an ideal ILS (instrumental line shape) for analysis of the spectra. In order to adapt the radiant energy received by the detector, an attenuator or different sizes of field stop can be inserted in the light path. These processes may alter the alignment of a high-resolution FTIR (Fourier transform infrared) spectrometer, and may result in bias due to ILS drift. In this paper, we first investigated the sensitivity of the ILS monitoring with respect to application of different kinds of attenuators for ground-based high-resolution FTIR spectrometers within the TCCON and NDACC networks. Both lamp and sun cell measurements were conducted after the insertion of five different attenuators in front of and behind the interferometer. The ILS characteristics derived from lamp and sun spectra are in good agreement. ILSs deduced from all lamp cell measurements were compared. As a result, the disturbances to the ILS of a high-resolution FTIR spectrometer with respect to the insertion of different attenuators at different positions were quantified. A potential strategy to adapt the incident intensity of a detector was finally deduced.

  8. Getting around Antarctica: new high-resolution mappings of the grounded and freely-floating boundaries of the Antarctic ice sheet created for the International Polar Year

    Directory of Open Access Journals (Sweden)

    R. Bindschadler

    2011-01-01

    Full Text Available The boundary of grounded ice and the location of ice transitioning to a freely floating state are mapped at 15-m resolution around the entire continent of Antarctica. These data products are produced by participants of the International Polar Year project ASAID using customized software combining Landsat-7 imagery and ICESat laser altimetry. The grounded ice boundary is 53 610 km long; 74% of it abuts to floating ice shelves or outlet glaciers, 19% is adjacent to open or sea-ice covered ocean, and 7% of the boundary are land terminations with bare rock. Elevations along each line are selected from 6 candidate digital elevation models: two created from the input ICESat laser altimetry and Landsat data, two from stereo satellite imagery, and two from compilations of primarily radar altimetry. Elevation selection and an assignment of confidence in the elevation value are based on agreement with ICESat elevation values and shape of the surface inferred from the Landsat imagery. Elevations along the freely-floating boundary (called the hydrostatic line are converted to ice thicknesses by applying a firn-correction factor and a flotation criterion. The relationship between the seaward offset of the hydrostatic line from the grounding line only weakly matches a prediction based on beam theory. Airborne data are used to validate the technique of grounding line mapping, elevation selection and ice thickness derivation. The mapped products along with the customized software to generate them and a variety of intermediate products are available from the National Snow and Ice Data Center.

  9. MTF study of planar small pixel pitch quantum IR detectors

    Science.gov (United States)

    Gravrand, O.; Baier, N.; Ferron, A.; Rochette, F.; Berthoz, J.; Rubaldo, L.; Cluzel, R.

    2014-06-01

    The actual trend in quantum IR detector development is the design of very small pixel pitch large arrays. From previously 30μm pitch, the standard pixel pitch is today 15μm and is expected to decrease to 12μm in the next few years. Furthermore, focal plane arrays (FPA) with pixel pitch as small as small as 10μm has been demonstrated. Such ultra-small pixel pitches are very small compared to the typical length ruling the electrical characteristics of the absorbing materials, namely the minority carrier diffusion length. As an example for low doped N type HgCdTe or InSb material, this diffusion length is of the order of 30 to 50μm, i.e. 3 to 5 times the targeted pixel pitches. This has strong consequences on the modulation transfer function (MTF) for planar structures, where the lateral extension of the photodiode is limited by diffusion. For such aspect ratios, the self-confinement of neighboring diodes may not be efficient enough to maintain optimal MTF. Therefore, this issue has to be addressed in order to take full benefits of the pixel pitch reduction in terms of image resolution. This paper aims at investigating the MTF evolution of HgCdTe and InSb FPAs decreasing the pixel pitch below 15μm. Both experimental measurements and finite element simulations are used to discuss this issue. Different scenarii will be compared, namely deep mesa etch between pixels, internal drift, surface recombination, thin absorbing layers.

  10. Development and characterization of diamond and 3D-silicon pixel detectors with ATLAS-pixel readout electronics

    Energy Technology Data Exchange (ETDEWEB)

    Mathes, Markus

    2008-12-15

    Hybrid pixel detectors are used for particle tracking in the innermost layers of current high energy experiments like ATLAS. After the proposed luminosity upgrade of the LHC, they will have to survive very high radiation fluences of up to 10{sup 16} particles per cm{sup 2} per life time. New sensor concepts and materials are required, which promise to be more radiation tolerant than the currently used planar silicon sensors. Most prominent candidates are so-called 3D-silicon and single crystal or poly-crystalline diamond sensors. Using the ATLAS pixel electronics different detector prototypes with a pixel geometry of 400 x 50 {mu}m{sup 2} have been built. In particular three devices have been studied in detail: a 3D-silicon and a single crystal diamond detector with an active area of about 1 cm{sup 2} and a poly-crystalline diamond detector of the same size as a current ATLAS pixel detector module (2 x 6 cm{sup 2}). To characterize the devices regarding their particle detection efficiency and spatial resolution, the charge collection inside a pixel cell as well as the charge sharing between adjacent pixels was studied using a high energy particle beam. (orig.)

  11. Beam test results of the BTeV silicon pixel detector

    CERN Document Server

    Appel, J A

    2001-01-01

    We report the results of the BTeV silicon pixel detector tests carried out in the MTest beam at Fermilab in 1999-2000. The pixel detector spatial resolution has been studied as a function of track inclination, sensor bias, and readout threshold.

  12. Approximate Approaches to Geometric Corrections of High Resolution Satellite Imagery

    Institute of Scientific and Technical Information of China (English)

    SHI Wenzhong; Ahmed Shaker

    2004-01-01

    The exploitation of different non-rigorous mathematical models as opposed to the satellite rigorous models is discussed for geometric corrections and topographic/thematic maps production of high-resolution satellite imagery (HRSI). Furthermore, this paper focuses on the effects of the number of GCPs and the terrain elevation difference within the area covered by the images on the obtained ground points accuracy. From the research, it is obviously found that non-rigorous orientation and triangulation models can be used successfully in most cases for 2D rectification and 3D ground points determination without a camera model or the satellite ephemeris data. In addition, the accuracy up to the sub-pixel level in plane and about one pixel in elevation can be achieved with a modest number of GCPs.

  13. THE OLKHON GEODYNAMIC PROVING GROUND (LAKE BAIKAL: HIGH RESOLUTION SATELLITE DATA AND GEOLOGICAL MAPS OF NEW GENERATION

    Directory of Open Access Journals (Sweden)

    Valentin S. Fedorovsky

    2015-09-01

    Full Text Available The Olkhon region of the Western Pribaikalie is highly attractive for geologists due to the presence of diverse metamorphic complexes and highly complicated combinations of folded structures in this region. The Olkhon region is located within the area of the Pribaikalsky National Park of Russia. At abundant outcrops in the subject area, various geological aspects resulting from the Early Palaeozoic collision system can be studied in detail. By its parameters, the subject area can be considered a «geodynamic proving ground». In recent years, abundant aerospace materials on the area have been accumulated, and long-term field studies resulted in many discoveries and findings which encourage critical revision of the initial conceptions. The material available allows compilation of a new package of geological maps in hard and electronic versions.

  14. WFC3 Pixel Area Maps

    Science.gov (United States)

    Kalirai, J. S.; Cox, C.; Dressel, L.; Fruchter, A.; Hack, W.; Kozhurina-Platais, V.; Mack, J.

    2010-04-01

    We present the pixel area maps (PAMs) for the WFC3/UVIS and WFC3/IR detectors, and discuss the normalization of these images. HST processed flt images suffer from geometric distortion and therefore have pixel areas that vary on the sky. The counts (electrons) measured for a source on these images depends on the position of the source on the detector, an effect that is implicitly corrected when these images are multidrizzled into drz files. The flt images can be multiplied by the PAMs to yield correct and uniform counts for a given source irrespective of its location on the image. To ensure consistency between the count rate measured for sources in drz images and near the center of flt images, we set the normalization of the PAMs to unity at a reference pixel near the center of the UVIS mosaic and IR detector, and set the SCALE in the IDCTAB equal to the square root of the area of this reference pixel. The implications of this choice for photometric measurements are discussed.

  15. VNR CMS Pixel detector replacement

    CERN Document Server

    2017-01-01

    Joel Butler, spokesperson of the CMS collaboration explains how a team from many different partner institutes installed a new detector in CMS. This detector is the silicon pixel detector and they’ve been working on it for about five years, to replace one of our existing detectors. This detectors measures particles closer to the beam than any of the other components of this huge detector behind me. It gives us the most precise picture of tracks as they come out of the collisions and expand and travel through the detector. This particular device has twice as many pixels, 120 million, as opposed to about 68 million in the old detector and it can take data faster and pump it out to the analysis more quickly. 00’53’’ Images of the descent, insertion and installation of first piece of the Pixel detector on Tue Feb 28. Images of the descent, insertion and installation of second piece of the Pixel and the two cylinders being joined.

  16. Compact all-CMOS spatiotemporal compressive sensing video camera with pixel-wise coded exposure.

    Science.gov (United States)

    Zhang, Jie; Xiong, Tao; Tran, Trac; Chin, Sang; Etienne-Cummings, Ralph

    2016-04-18

    We present a low power all-CMOS implementation of temporal compressive sensing with pixel-wise coded exposure. This image sensor can increase video pixel resolution and frame rate simultaneously while reducing data readout speed. Compared to previous architectures, this system modulates pixel exposure at the individual photo-diode electronically without external optical components. Thus, the system provides reduction in size and power compare to previous optics based implementations. The prototype image sensor (127 × 90 pixels) can reconstruct 100 fps videos from coded images sampled at 5 fps. With 20× reduction in readout speed, our CMOS image sensor only consumes 14μW to provide 100 fps videos.

  17. Silicon pixel R&D for CLIC

    CERN Document Server

    AUTHOR|(SzGeCERN)754303

    2016-01-01

    Challenging detector requirements are imposed by the physics goals at the future multi-TeV e+e- Compact Linear Collider (CLIC). A single point resolution of 3μm for the vertex detector and 7μm for the tracker is required. Moreover, the CLIC vertex detector and tracker need to be extremely light weighted with a material budget of 0.2 % X0 per layer in the ver- tex detector and 1-2%X0 in the tracker. A fast time slicing of 10ns is further required to suppress background from beam-beam interactions. A wide range of sensor and readout ASIC technologies are investigated within the CLIC silicon pixel R&D effort. Various hybrid planar sensor assemblies with a pixel size of 25x25μm2 and 55x55μm2 have been produced and characterised by laboratory measurements and during test-beam campaigns. Experimental and simulation results for thin (50μm-500μm) slim edge and active-edge planar, and High-Voltage CMOS sensors hybridised to various readout ASICs (Timepix, Timepix3, CLICpix) are presented.

  18. Silicon pixel R&D for CLIC

    Science.gov (United States)

    Munker, M.

    2017-01-01

    Challenging detector requirements are imposed by the physics goals at the future multi-TeV e+ e‑ Compact Linear Collider (CLIC). A single point resolution of 3 μm for the vertex detector and 7 μm for the tracker is required. Moreover, the CLIC vertex detector and tracker need to be extremely light weighted with a material budget of 0.2% X0 per layer in the vertex detector and 1–2% X0 in the tracker. A fast time slicing of 10 ns is further required to suppress background from beam-beam interactions. A wide range of sensor and readout ASIC technologies are investigated within the CLIC silicon pixel R&D effort. Various hybrid planar sensor assemblies with a pixel size of 25×25 μm2 and 55×55 μm2 have been produced and characterised by laboratory measurements and during test-beam campaigns. Experimental and simulation results for thin (50 μm–500 μm) slim edge and active-edge planar, and High-Voltage CMOS sensors hybridised to various readout ASICs (Timepix, Timepix3, CLICpix) are presented.

  19. Getting around Antarctica: new high-resolution mappings of the grounded and freely-floating boundaries of the Antarctic ice sheet created for the International Polar Year

    Directory of Open Access Journals (Sweden)

    R. Bindschadler

    2011-07-01

    Full Text Available Two ice-dynamic transitions of the Antarctic ice sheet – the boundary of grounded ice features and the freely-floating boundary – are mapped at 15-m resolution by participants of the International Polar Year project ASAID using customized software combining Landsat-7 imagery and ICESat/GLAS laser altimetry. The grounded ice boundary is 53 610 km long; 74 % abuts to floating ice shelves or outlet glaciers, 19 % is adjacent to open or sea-ice covered ocean, and 7 % of the boundary ice terminates on land. The freely-floating boundary, called here the hydrostatic line, is the most landward position on ice shelves that expresses the full amplitude of oscillating ocean tides. It extends 27 521 km and is discontinuous. Positional (one-sigma accuracies of the grounded ice boundary vary an order of magnitude ranging from ±52 m for the land and open-ocean terminating segments to ±502 m for the outlet glaciers. The hydrostatic line is less well positioned with errors over 2 km. Elevations along each line are selected from 6 candidate digital elevation models based on their agreement with ICESat elevation values and surface shape inferred from the Landsat imagery. Elevations along the hydrostatic line are converted to ice thicknesses by applying a firn-correction factor and a flotation criterion. BEDMAP-compiled data and other airborne data are compared to the ASAID elevations and ice thicknesses to arrive at quantitative (one-sigma uncertainties of surface elevations of ±3.6, ±9.6, ±11.4, ±30 and ±100 m for five ASAID-assigned confidence levels. Over one-half of the surface elevations along the grounded ice boundary and over one-third of the hydrostatic line elevations are ranked in the highest two confidence categories. A comparison between ASAID-calculated ice shelf thicknesses and BEDMAP-compiled data indicate a thin-ice bias of 41.2 ± 71.3 m for the ASAID ice thicknesses. The relationship between the seaward offset of the hydrostatic line

  20. Getting around Antarctica: New High-Resolution Mappings of the Grounded and Freely-Floating Boundaries of the Antarctic Ice Sheet Created for the International Polar Year

    Science.gov (United States)

    Bindschadler, R.; Choi, H.; Wichlacz, A.; Bingham, R.; Bohlander, J.; Brunt, K.; Corr, H.; Drews, R.; Fricker, H.; Hall, M.; Hindmarsh, R.; Kohler, J.; Padman, L.; Rack, W.; Rotschkly, G.; Urbini, S.; Vornberger, P.; Young, N.

    2011-01-01

    Two ice-dynamic transitions of the Antarctic ice sheet - the boundary of grounded ice features and the freely-floating boundary - are mapped at 15-m resolution by participants of the International Polar Year project ASAID using customized software combining Landsat-7 imagery and ICESat/GLAS laser altimetry. The grounded ice boundary is 53 610 km long; 74% abuts to floating ice shelves or outlet glaciers, 19% is adjacent to open or sea-ice covered ocean, and 7% of the boundary ice terminates on land. The freely-floating boundary, called here the hydrostatic line, is the most landward position on ice shelves that expresses the full amplitude of oscillating ocean tides. It extends 27 521 km and is discontinuous. Positional (one-sigma) accuracies of the grounded ice boundary vary an order of magnitude ranging from +/- 52m for the land and open-ocean terminating segments to +/- 502m for the outlet glaciers. The hydrostatic line is less well positioned with errors over 2 km. Elevations along each line are selected from 6 candidate digital elevation models based on their agreement with ICESat elevation values and surface shape inferred from the Landsat imagery. Elevations along the hydrostatic line are converted to ice thicknesses by applying a firn-correction factor and a flotation criterion. BEDMAP-compiled data and other airborne data are compared to the ASAID elevations and ice thicknesses to arrive at quantitative (one-sigma) uncertainties of surface elevations of +/-3.6, +/-9.6, +/-11.4, +/-30 and +/-100m for five ASAID-assigned confidence levels. Over one-half of the surface elevations along the grounded ice boundary and over one-third of the hydrostatic line elevations are ranked in the highest two confidence categories. A comparison between ASAID-calculated ice shelf thicknesses and BEDMAP-compiled data indicate a thin-ice bias of 41.2+/-71.3m for the ASAID ice thicknesses. The relationship between the seaward offset of the hydrostatic line from the grounded ice

  1. Mapping High-Resolution Soil Moisture over Heterogeneous Cropland Using Multi-Resource Remote Sensing and Ground Observations

    Directory of Open Access Journals (Sweden)

    Lei Fan

    2015-10-01

    Full Text Available High spatial resolution soil moisture (SM data are crucial in agricultural applications, river-basin management, and understanding hydrological processes. Merging multi-resource observations is one of the ways to improve the accuracy of high spatial resolution SM data in the heterogeneous cropland. In this paper, the Bayesian Maximum Entropy (BME methodology is implemented to merge the following four types of observed data to obtain the spatial distribution of SM at 100 m scale: soil moisture observed by wireless sensor network (WSN, Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER-derived soil evaporative efficiency (SEE, irrigation statistics, and Polarimetric L-band Multi-beam Radiometer (PLMR-derived SM products (~700 m. From the poor BME predictions obtained by merging only WSN and SEE data, we observed that the SM heterogeneity caused by irrigation and the attenuating sensitivity of the SEE data to SM caused by the canopies result in BME prediction errors. By adding irrigation statistics to the merged datasets, the overall RMSD of the BME predictions during the low-vegetated periods can be successively reduced from 0.052 m3·m−3 to 0.033 m3·m−3. The coefficient of determination (R2 and slope between the predicted and in situ measured SM data increased from 0.32 to 0.64 and from 0.38 to 0.82, respectively, but large estimation errors occurred during the moderately vegetated periods (RMSD = 0.041 m3·m−3, R = 0.43 and the slope = 0.41. Further adding the downscaled SM information from PLMR SM products to the merged datasets, the predictions were satisfactorily accurate with an RMSD of 0.034 m3·m−3, R2 of 0.4 and a slope of 0.69 during moderately vegetated periods. Overall, the results demonstrated that merging multi-resource observations into SM estimations can yield improved accuracy in heterogeneous cropland.

  2. High-Spectral Resolution, Ground-Based Observations of the Lunar Sodium and Potassium Exosphere During the LADEE Mission.

    Science.gov (United States)

    Kuruppuaratchi, D. C. P.; Oliversen, R. J.; Mierkiewicz, E. J.; Derr, N. J.; Freer, C. W.; Gallant, M. A.; Gardner, D. D.; Lupie, O. L.; Spalsbury, L. C.; Wilson, M. L.

    2014-12-01

    We apply high resolution spectroscopy to investigate the lunar exosphere by measuring sodium and potassium spectral line profiles to determine the variations in exospheric effective temperatures and velocities. Observations were made at the National Solar Observatory McMath-Pierce Telescope concurrent with the Lunar Atmosphere and Dust Environment Explorer (LADEE) science phase. We used a dual-etalon Fabry-Perot spectrometer with a resolving power of 200,000 to measure the line widths and radial velocity Doppler shifts of the sodium D2 (5889.951 Å) and potassium D1 (7698.965 Å) emission lines. Data were taken during the full moon periods from November 2013 through May 2014 with the exception of March 2014. The instrument's Field of View (FOV) of 3 arcmin (~360 km) was positioned at several locations, centered at 1.5 arcmin, off the East and West limbs. The deconvolved line widths indicate sodium temperatures pre- and post- magnetotail passage are on the order of 1600 K while temperatures during passage through the magnetotail are on the order of a several thousand Kelvin. Unlike sodium, the potassium deconvolved line widths indicate pre-magnetotail passage several hundred degrees hotter than the post-magnetotail passage temperatures. Additionally, both sodium and potassium intensities were brighter after magnetotail passage than before. This work was partially supported by the NASA Planetary Astronomy programs, NNX11AE38G and NNX13AL30G.

  3. The high resolution topographic evolution of an active retrogressive thaw slump compiled from a decade of photography, ground surveys, laser scans and satellite imagery

    Science.gov (United States)

    Crosby, B. T.; Barnhart, T. B.; Rowland, J. C.

    2015-12-01

    Remote sensing imagery has enables the temporal reconstruction of thermal erosion features including lakes, shorelines and hillslope failures in remote Arctic locations, yet these planar data limit analysis to lines and areas. This study explores the application of varying techniques to reconstruct the three dimensional evolution of a single thermal erosion feature using a mixture of opportunistic oblique photos, ground surveys and satellite imagery. At the Selawik River retrogressive thaw slump in northwest Alaska, a bush plane collected oblique aerial photos when the feature was first discovered in 2004 and in subsequent years. These images were recently processed via Structure from Motion to generate georeferenced point clouds for the years prior to the initiation of our research. High resolution ground surveys in 2007, 2009 and 2010 were completed using robotic total station. Terrestrial laser scans (TLS) were collected in the summers of 2011 and 2012. Analysis of stereo satellite imagery from 2012 and 2015 enable continued monitoring of the feature after ground campaigns ended. As accurate coregistraion between point clouds is vital to topographic change detection, all prior and subsequent datasets were georeferenced to stable features observed in the 2012 TLS scan. Though this coregistration introduces uncertainty into each image, the magnitudes of uncertainty are significantly smaller than the topographic changes detected. Upslope retreat of the slump headwall generally decreases over time as the slump floor progresses from a highly dissected gully topography to a low relief, earthflow dominated depositional plane. The decreasing slope of the slump floor diminishes transport capacity, resulting in the progressive burial of the slump headwall, thus decreasing headwall retreat rates. This self-regulation of slump size based on feature relief and transport capacity suggests a capacity to predict the maximum size a given feature can expand to before

  4. Planar Pixel Sensors for the ATLAS Upgrade: Beam Tests results

    CERN Document Server

    Weingarten, J; Beimforde, M; Benoit, M; Bomben, M; Calderini, G; Gallrapp, C; George, M; Gibson, S; Grinstein, S; Janoska, Z; Jentzsch, J; Jinnouchi, O; Kishida, T; La Rosa, A; Libov, V; Macchiolo, A; Marchiori, G; Münstermann, D; Nagai, R; Piacquadio, G; Ristic, B; Rubinskiy, I; Rummler, A; Takubo, Y; Troska, G; Tsiskaridtze, S; Tsurin, I; Unno, Y; Weigel, P; Wittig, T

    2012-01-01

    Results of beam tests with planar silicon pixel sensors aimed towards the ATLAS Insertable B-Layer and High Luminosity LHC (HL-LHC) upgrades are presented. Measurements include spatial resolution, charge collection performance and charge sharing between neighbouring cells as a function of track incidence angle for different bulk materials. Measurements of n-in-n pixel sensors are presented as a function of fluence for different irradiations. Furthermore p-type silicon sensors from several vendors with slightly differing layouts were tested. All tested sensors were connected by bump-bonding to the ATLAS Pixel read-out chip. We show that both n-type and p-type tested planar sensors are able to collect significant charge even after integrated fluences expected at HL-LHC.

  5. The first bump-bonded pixel detectors on CVD diamond

    Energy Technology Data Exchange (ETDEWEB)

    Adam, W.; Bauer, C.; Berdermann, E.; Bergonzo, P.; Bogani, F.; Borchi, E.; Brambilla, A.; Bruzzi, M.; Colledani, C.; Conway, J.; Dabrowski, W.; Delpierre, P.; Deneuville, A.; Dulinski, W.; Eijk, B. van; Fallou, A.; Fizzotti, F.; Foulon, F.; Friedl, M.; Gan, K.K.; Gheeraert, E.; Grigoriev, E.; Hallewell, G.; Hall-Wilton, R.; Han, S.; Hartjes, F.; Hrubec, J.; Husson, D.; Kagan, H.; Kania, D.; Kaplon, J.; Karl, C.; Kass, R.; Krammer, M.; Logiudice, A.; Lu, R.; Manfredi, P.F.; Manfredotti, C.; Marshall, R.D.; Meier, D.; Mishina, M.; Oh, A.; Palmieri, V.G.; Pan, L.S.; Peitz, A.; Pernicka, M.; Pirollo, S.; Polesello, P.; Pretzl, K.; Re, V.; Riester, J.L.; Roe, S.; Roff, D.; Rudge, A.; Schnetzer, S.; Sciortino, S.; Speziali, V.; Stelzer, H.; Steuerer, J.; Stone, R.; Tapper, R.J.; Tesarek, R.; Trawick, M.; Trischuk, W. E-mail: william@physics.utoronto.ca; Turchetta, R.; Vittone, E.; Wagner, A.; Walsh, A.M.; Wedenig, R.; Weilhammer, P.; Zeuner, W.; Ziock, H.; Zoeller, M.; Charles, E.; Ciocio, A.; Dao, K.; Einsweiler, K.; Fasching, D.; Gilchriese, M.; Joshi, A.; Kleinfelder, S.; Milgrome, O.; Palaio, N.; Richardson, J.; Sinervo, P.; Zizka, G

    1999-11-01

    Diamond is a nearly ideal material for detecting ionising radiation. Its outstanding radiation hardness, fast charge collection and low leakage current allow it to be used in high radiation environments. These characteristics make diamond sensors particularly appealing for use in the next generation of pixel detectors. Over the last year, the RD42 collaboration has worked with several groups that have developed pixel readout electronics in order to optimise diamond sensors for bump-bonding. This effort resulted in an operational diamond pixel sensor that was tested in a pion beam. We demonstrate that greater than 98% of the channels were successfully bump-bonded and functioning. The device shows good overall hit efficiency as well as clear spatial hit correlation to tracks measured in a silicon reference telescope. A position resolution of 14.8 {mu}m was observed, consistent with expectations given the detector pitch.

  6. Performance of the INTPIX6 SOI pixel detector

    Science.gov (United States)

    Arai, Y.; Bugiel, Sz.; Dasgupta, R.; Idzik, M.; Kapusta, P.; Kucewicz, W.; Miyoshi, T.; Turala, M.

    2017-01-01

    Characterization of the monolithic pixel detector INPTIX6, designed at KEK and fabricated in Lapis 0.2 μ m Fully-Depleted, Low-Leakage Silicon-On-Insulator (SOI) CMOS technology, was performed. The INTPIX6 comprises a large area of 1408 × 896 integrating type squared pixels of 12 micron pitch. In this work the performance and measurement results of the prototypes produced on lower resistivity Czochralski type (CZ-n) and high resistivity floating zone (FZ-n) sensor wafers are presented. Using 241Am radioactive source the noise of INTPIX6 was measured, showing the ENC (Equivalent Noise Charge) of about 70 e-. The resolution calculated from the FWHM of the Iron-55 X-ray peak was about 100 e-. The radiation hardness of the SOI pixel detector was also investigated. The CZ-n type INTPIX6 received a dose of 60 krad and its performance has been continuously monitored during the irradiation.

  7. Digital Power Consumption Estimations for CHIPIX65 Pixel Readout Chip

    CERN Document Server

    Marcotulli, Andrea

    2016-01-01

    New hybrid pixel detectors with improved resolution capable of dealing with hit rates up to 3 GHz/cm2 will be required for future High Energy Physics experiments in the Large Hadron Collider (LHC) at CERN. Given this, the RD53 collaboration works on the design of the next generation pixel readout chip needed for both the ATLAS and CMS detector phase 2 pixel upgrades. For the RD53 demonstrator chip in 65nm CMOS technology, different architectures are considered. In particular the purpose of this work is estimating the power consumption of the digital architecture of the readout ASIC developed by CHIPIX65 project of the INFN National Scientific Committee. This has been done with modern chip design tools integrated with the VEPIX53 simulation framework that has been developed within the RD53 collaboration in order to assess the performance of the system in very high rate, high energy physics experiments.

  8. Testbeam and Laboratory Characterization of CMS 3D Pixel Sensors

    CERN Document Server

    Bubna, M; Krzywda, A; Koybasi, O; Arndt, K; Bortoletto, D; Shipsey, I; Bolla, G; Kok, A; Hansen, T -E; Hansen, T A; Jensen, G U; Brom, J M; Boscardin, M; Chramowicz, J; Cumalat, J; Betta, G F Dalla; Dinardo, M; Godshalk, A; Jones, M; Krohn, M D; Kumar, A; Lei, C M; Moroni, L; Perera, L; Povoli, M; Prosser, A; Rivera, R; Solano, A; Obertino, M M; Kwan, S; Uplegger, L; Via, C D; Vigani, L; Wagner, S

    2014-01-01

    The pixel detector is the innermost tracking device in CMS, reconstructing interaction vertices and charged particle trajectories. The sensors located in the innermost layers of the pixel detector must be upgraded for the ten-fold increase in luminosity expected with the High- Luminosity LHC (HL-LHC) phase. As a possible replacement for planar sensors, 3D silicon technology is under consideration due to its good performance after high radiation fluence. In this paper, we report on pre- and post- irradiation measurements for CMS 3D pixel sensors with different electrode configurations. The effects of irradiation on electrical properties, charge collection efficiency, and position resolution of 3D sensors are discussed. Measurements of various test structures for monitoring the fabrication process and studying the bulk and surface properties, such as MOS capacitors, planar and gate-controlled diodes are also presented.

  9. Possibilities of MERIS for sub-pixel regional land cover mapping

    NARCIS (Netherlands)

    Zurita Milla, R.; Schaepman, M.E.; Clevers, J.G.P.W.

    2005-01-01

    The Medium Resolution Imaging Spectrometer, MERIS, on board of ENVISAT-1 fulfils the information gap between the current high and low spatial resolution sensors. In this respect, the use of MERIS full resolution data (300 m pixel size) has a great potential for regional and global land cover mapping

  10. Achieving sub-pixel geolocation accuracy in support of MODIS land science

    Science.gov (United States)

    Wolfe, R.E.; Nishihama, M.; Fleig, A.J.; Kuyper, J.A.; Roy, D.P.; Storey, J.C.; Patt, F.S.

    2002-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) was launched in December 1999 on the polar orbiting Terra spacecraft and since February 2000 has been acquiring daily global data in 36 spectral bands-29 with 1 km, five with 500 m, and two with 250 m nadir pixel dimensions. The Terra satellite has on-board exterior orientation (position and attitude) measurement systems designed to enable geolocation of MODIS data to approximately 150 m (1??) at nadir. A global network of ground control points is being used to determine biases and trends in the sensor orientation. Biases have been removed by updating models of the spacecraft and instrument orientation in the MODIS geolocation software several times since launch and have improved the MODIS geolocation to approximately 50 m (1??) at nadir. This paper overviews the geolocation approach, summarizes the first year of geolocation analysis, and overviews future work. The approach allows an operational characterization of the MODIS geolocation errors and enables individual MODIS observations to be geolocated to the sub-pixel accuracies required for terrestrial global change applications. ?? 2002 Elsevier Science Inc. All rights reserved.

  11. Status of the ATLAS pixel detector

    CERN Document Server

    Saavedra Aldo, F

    2005-01-01

    The ATLAS pixel detector is currently being constructed and will be installed in 2006 to be ready for commissioning at the Large Hadron Collider. The complete pixel detector is composed of three concentric barrels and six disks that are populated by 1744 ATLAS Pixel modules. The main components of the pixel module are the readout electronics and the silicon sensor whose active region is instrumented with rectangular pixels. The module has been designed to be able to survive 10 years of operation within the ATLAS detector. A brief description of the pixel detector will be presented with results and problems encountered during the production stage.

  12. Detection of water absorption in the dayside atmosphere of HD 189733 b using ground-based high-resolution spectroscopy at 3.2 microns

    CERN Document Server

    Birkby, J L; Brogi, M; de Mooij, E J W; Schwarz, H; Albrecht, S; Snellen, I A G

    2013-01-01

    We report a 5 sigma detection of water absorption features in the dayside spectrum of the hot Jupiter HD 189733 b. We used high-resolution (R~100,000) spectra taken at 3.2 microns with CRIRES on the VLT to trace the radial velocity shift of the water features in the planet's dayside atmosphere during 5 hours of its 2.2 day orbit as it approached secondary eclipse. Despite considerable telluric contamination in this wavelength regime, we detect the signal within our uncertainties at the expected combination of systemic velocity (Vsys=-3 +5-6 km/s) and planet orbital velocity (Kp=154 +14-10 km/s), and determine a H2O line contrast ratio of (1.3+/-0.2)x10^-3 with respect to the stellar continuum. We find no evidence of significant absorption or emission from other carbon-bearing molecules, such as methane, although we do note a marginal increase in the significance of our detection with the inclusion of carbon dioxide in our template spectrum. This result demonstrates that ground-based, high-resolution spectrosc...

  13. High resolution seismic imaging at the Odessa (TX) meteorite impact site: the ground-impact geohazard and integration with magnetic gradiometry and time-domain electromagnetics

    Science.gov (United States)

    Soule, D.; Everett, M.

    2007-05-01

    Comet and asteroid bombardment along with impact crater formation has occurred continuously throughout Earth's history. The greatest impact-related geohazard is due to moderate sized impactors which represent the worst-case trade-off between frequency of occurrence, difficulty of mitigation, and severity of environmental destruction. Impacts in this size range pose a significant regional threat to densely populated areas. The primary objective of this research is to evaluate the ground-impact geohazard via high resolution seismic imaging of the remnants of a moderate-sized impact event, namely that associated with the 50 ka Odessa (TX) Group IAB iron meteorite. We provide high-resolution subsurface images of the 150-m diameter crater, the outcropping crater rim, the ejecta blanket, and the surrounding plain. The subsurface images are analyzed in terms of the deformation and thrusting of the underlying Cretaceous limestone and shale strata and the likely environmental effects caused by the impact. The analysis will build upon and extend our previous geophysical investigations based on magnetic gradiometry and time-domain electromagnetic data.

  14. Comparison of a pixelated semiconductor detector and a non-pixelated scintillation detector in pinhole SPECT system for small animal study.

    Science.gov (United States)

    Iida, Hirokazu; Ogawa, Koichi

    2011-02-01

    The aim of this work was to evaluate a pixelated semiconductor detector and non-pixelated scintillation detector in a pinhole SPECT system for small animal imaging. We assumed two pixelated CdTe semiconductor detectors (a monolithic type and a modular type) and two non-pixelated NaI(Tl) scintillation detectors (a conventional type and a large detector field type). For the monolithic semiconductor detector we assumed that the size of a pixel was 1.0 × 1.0 mm², the thickness 1 mm, and an effective detector field 128 × 128 mm². For the modular-type semiconductor detector we assumed that the size of a pixel was 2.5 × 2.5 mm², the thickness 5 mm, and an effective detector field 320 × 320 mm². For the two scintillation detectors we assumed that the size of a pixel was 1.4 × 1.4 mm² and the intrinsic spatial resolution 4.0 mm FWHM, and the thickness 9 mm. For the conventional scintillation detector we assumed that the effective detector field was 179.2 × 179.2 mm², and for the large field scintillation detector 358.2 × 358.2 mm² and the magnification factor two. In the simulation we used a pinhole collimator with a pinhole size of 0.3 mm. We reconstructed SPECT images of hot-rod and cold-channel phantoms with projection data calculated with a Monte Carlo method assuming a fixed data acquisition time, and evaluated the image quality with respect to contrast and spatial resolution. In addition, we calculated the scatter fraction to compare the amount of scattered photons between the pixelated and non-pixelated detectors. The image quality of the modular-type pixelated detector was similar to that of the non-pixelated detector operated with a twofold magnified data acquisition. The scattered photons and the parallax effect in the pixelated detector were small and similar to those in the non-pixelated detector. The performance of a modular-type pixelated semiconductor detector was almost the same as that of a non-pixelated scintillation detector with a magnified

  15. Improving Quantitative Precipitation Estimation via Data Fusion of High-Resolution Ground-based Radar Network and CMORPH Satellite-based Product

    Science.gov (United States)

    Cifelli, R.; Chen, H.; Chandrasekar, V.; Xie, P.

    2015-12-01

    A large number of precipitation products at multi-scales have been developed based upon satellite, radar, and/or rain gauge observations. However, how to produce optimal rainfall estimation for a given region is still challenging due to the spatial and temporal sampling difference of different sensors. In this study, we develop a data fusion mechanism to improve regional quantitative precipitation estimation (QPE) by utilizing satellite-based CMORPH product, ground radar measurements, as well as numerical model simulations. The CMORPH global precipitation product is essentially derived based on retrievals from passive microwave measurements and infrared observations onboard satellites (Joyce et al. 2004). The fine spatial-temporal resolution of 0.05o Lat/Lon and 30-min is appropriate for regional hydrologic and climate studies. However, it is inadequate for localized hydrometeorological applications such as urban flash flood forecasting. Via fusion of the Regional CMORPH product and local precipitation sensors, the high-resolution QPE performance can be improved. The area of interest is the Dallas-Fort Worth (DFW) Metroplex, which is the largest land-locked metropolitan area in the U.S. In addition to an NWS dual-polarization S-band WSR-88DP radar (i.e., KFWS radar), DFW hosts the high-resolution dual-polarization X-band radar network developed by the center for Collaborative Adaptive Sensing of the Atmosphere (CASA). This talk will present a general framework of precipitation data fusion based on satellite and ground observations. The detailed prototype architecture of using regional rainfall instruments to improve regional CMORPH precipitation product via multi-scale fusion techniques will also be discussed. Particularly, the temporal and spatial fusion algorithms developed for the DFW Metroplex will be described, which utilizes CMORPH product, S-band WSR-88DP, and X-band CASA radar measurements. In order to investigate the uncertainties associated with each

  16. How big is an OMI pixel?

    Science.gov (United States)

    de Graaf, Martin; Sihler, Holger; Tilstra, Lieuwe G.; Stammes, Piet

    2016-08-01

    The Ozone Monitoring Instrument (OMI) is a push-broom imaging spectrometer, observing solar radiation backscattered by the Earth's atmosphere and surface. The incoming radiation is detected using a static imaging CCD (charge-coupled device) detector array with no moving parts, as opposed to most of the previous satellite spectrometers, which used a moving mirror to scan the Earth in the across-track direction. The field of view (FoV) of detector pixels is the solid angle from which radiation is observed, averaged over the integration time of a measurement. The OMI FoV is not quadrangular, which is common for scanning instruments, but rather super-Gaussian shaped and overlapping with the FoV of neighbouring pixels. This has consequences for pixel-area-dependent applications, like cloud fraction products, and visualisation.The shapes and sizes of OMI FoVs were determined pre-flight by theoretical and experimental tests but never verified after launch. In this paper the OMI FoV is characterised using collocated MODerate resolution Imaging Spectroradiometer (MODIS) reflectance measurements. MODIS measurements have a much higher spatial resolution than OMI measurements and spectrally overlap at 469 nm. The OMI FoV was verified by finding the highest correlation between MODIS and OMI reflectances in cloud-free scenes, assuming a 2-D super-Gaussian function with varying size and shape to represent the OMI FoV. Our results show that the OMPIXCOR product 75FoV corner coordinates are accurate as the full width at half maximum (FWHM) of a super-Gaussian FoV model when this function is assumed. The softness of the function edges, modelled by the super-Gaussian exponents, is different in both directions and is view angle dependent.The optimal overlap function between OMI and MODIS reflectances is scene dependent and highly dependent on time differences between overpasses, especially with clouds in the scene. For partially clouded scenes, the optimal overlap function was

  17. Medipix3: A 64 k pixel detector readout chip working in single photon counting mode with improved spectrometric performance

    CERN Document Server

    Ballabriga, R; Wong, W; Heijne, E; Campbell, M; Llopart, X

    2011-01-01

    Medipix3 is a 256 x 256 channel hybrid pixel detector readout chip working in a single photon counting mode with a new inter-pixel architecture, which aims to improve the energy resolution in pixelated detectors by mitigating the effects of charge sharing between channels. Charges are summed in all 2 x 2 pixel clusters on the chip and a given hit is allocated locally to the pixel summing circuit with the biggest total charge on an event-by-event basis. Each pixel contains also two 12-bit binary counters with programmable depth and overflow control. The chip is configurable such that either the dimensions of each detector pixel match those of one readout pixel or detector pixels are four times greater in area than the readout pixels. In the latter case, event-by-event summing is still possible between the larger pixels. Each pixel has around 1600 transistors and the analog static power consumption is below 15 mu W in the charge summing mode and 9 mu W in the single pixel mode. The chip has been built in an 8-m...

  18. Multiport solid-state imager characterization at variable pixel rates

    Energy Technology Data Exchange (ETDEWEB)

    Yates, G.J.; Albright, K.A. [Los Alamos National Lab., NM (United States); Turko, B.T. [Lawrence Berkeley Lab., CA (United States)

    1993-08-01

    The imaging performance of an 8-port Full Frame Transfer Charge Coupled Device (FFT CCD) as a function of several parameters including pixel clock rate is presented. The device, model CCD- 13, manufactured by English Electric Valve (EEV) is a 512 {times} 512 pixel array designed with four individual programmable bidirectional serial registers and eight output amplifiers permitting simultaneous readout of eight segments (128 horizontal {times} 256 vertical pixels) of the array. The imager was evaluated in Los Alamos National Laboratory`s High-Speed Solid-State Imager Test Station at true pixel rates as high as 50 MHz for effective imager pixel rates approaching 400 MHz from multiporting. Key response characteristics measured include absolute responsivity, Charge-Transfer-Efficiency (CTE), dynamic range, resolution, signal-to-noise ratio, and electronic and optical crosstalk among the eight video channels. Preliminary test results and data obtained from the CCD-13 will be presented and the versatility/capabilities of the test station will be reviewed.

  19. Operational Experience with the ATLAS Pixel Detector at LHC

    CERN Document Server

    Keil, M

    2013-01-01

    The ATLAS Pixel Detector is the innermost detector of the ATLAS experiment at the Large Hadron Collider at CERN, providing high-resolution measurements of charged particle tracks in the high radiation environment close to the collision region. This capability is vital for the identification and measurement of proper decay times of long-lived particles such as b-hadrons, and thus crucial for the ATLAS physics program. The detector provides hermetic coverage with three cylindrical layers and three layers of forward and backward pixel detectors. It consists of approximately 80 million pixels that are individually read out via front-end chips bump-bonded to 1744 n-on-n silicon substrates. In this paper results from the successful operation of the Pixel Detector at the LHC will be presented, including calibration procedures, detector performance and measurements of radiation damage. The detector performance is excellent: more than 95% of the pixels are operational, noise occupancy and hit efficiency exceed the des...

  20. Improving Charge-Collection Efficiency of Kyoto's SOI Pixel Sensors

    CERN Document Server

    Matsumura, Hideaki; Tanaka, Takaaki; Takeda, Ayaki; Ito, Makoto; Ohmura, Syunichi; Arai, Yasuo; Mori, Koji; Nishioka, Yusuke; Takenaka, Ryota; Kohmura, Takayoshi

    2015-01-01

    We have been developing X-ray SOIPIXs for next-generation satellites for X-ray astronomy. Their high time resolution ($\\sim10~\\mu$s) and event-trigger-output function enable us to read out without pile-ups and to use anti-coincidence systems. Their performance in imaging spectroscopy is comparable to that in the CCDs. A problem in our previous model was degradation of charge-collection efficiency (CCE) at pixel borders. We measured the response in the sub-pixel scale, using finely collimated X-ray beams at $10~\\mu$m\\Phi$ at SPring-8, and investigated the non-uniformity of the CCE within a pixel. We found that the X-ray detection efficiency and CCE degrade in the sensor region under the pixel circuitry placed outside the buried p-wells (BPW). A 2D simulation of the electric fields shows that the isolated pixel-circuitry outside the BPW creates local minimums in the electric potentials at the interface between the sensor and buried oxide layers. Thus, a part of signal charge is trapped there and is not collecte...

  1. 3D track reconstruction capability of a silicon hybrid active pixel detector

    Science.gov (United States)

    Bergmann, Benedikt; Pichotka, Martin; Pospisil, Stanislav; Vycpalek, Jiri; Burian, Petr; Broulim, Pavel; Jakubek, Jan

    2017-06-01

    Timepix3 detectors are the latest generation of hybrid active pixel detectors of the Medipix/Timepix family. Such detectors consist of an active sensor layer which is connected to the readout ASIC (application specific integrated circuit), segmenting the detector into a square matrix of 256 × 256 pixels (pixel pitch 55 μm). Particles interacting in the active sensor material create charge carriers, which drift towards the pixelated electrode, where they are collected. In each pixel, the time of the interaction (time resolution 1.56 ns) and the amount of created charge carriers are measured. Such a device was employed in an experiment in a 120 GeV/c pion beam. It is demonstrated, how the drift time information can be used for "4D" particle tracking, with the three spatial dimensions and the energy losses along the particle trajectory (dE/dx). Since the coordinates in the detector plane are given by the pixelation ( x, y), the x- and y-resolution is determined by the pixel pitch (55 μm). A z-resolution of 50.4 μm could be achieved (for a 500 μm thick silicon sensor at 130 V bias), whereby the drift time model independent z-resolution was found to be 28.5 μm.

  2. The ATLAS Silicon Pixel Sensors

    CERN Document Server

    Alam, M S; Einsweiler, K F; Emes, J; Gilchriese, M G D; Joshi, A; Kleinfelder, S A; Marchesini, R; McCormack, F; Milgrome, O; Palaio, N; Pengg, F; Richardson, J; Zizka, G; Ackers, M; Andreazza, A; Comes, G; Fischer, P; Keil, M; Klasen, V; Kühl, T; Meuser, S; Ockenfels, W; Raith, B; Treis, J; Wermes, N; Gössling, C; Hügging, F G; Wüstenfeld, J; Wunstorf, R; Barberis, D; Beccherle, R; Darbo, G; Gagliardi, G; Gemme, C; Morettini, P; Musico, P; Osculati, B; Parodi, F; Rossi, L; Blanquart, L; Breugnon, P; Calvet, D; Clemens, J-C; Delpierre, P A; Hallewell, G D; Laugier, D; Mouthuy, T; Rozanov, A; Valin, I; Aleppo, M; Caccia, M; Ragusa, F; Troncon, C; Lutz, Gerhard; Richter, R H; Rohe, T; Brandl, A; Gorfine, G; Hoeferkamp, M; Seidel, SC; Boyd, GR; Skubic, P L; Sícho, P; Tomasek, L; Vrba, V; Holder, M; Ziolkowski, M; D'Auria, S; del Papa, C; Charles, E; Fasching, D; Becks, K H; Lenzen, G; Linder, C

    2001-01-01

    Prototype sensors for the ATLAS silicon pixel detector have been developed. The design of the sensors is guided by the need to operate them in the severe LHC radiation environment at up to several hundred volts while maintaining a good signal-to-noise ratio, small cell size, and minimal multiple scattering. The ability to be operated under full bias for electrical characterization prior to the attachment of the readout integrated circuit electronics is also desired.

  3. SAR Image Complex Pixel Representations

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-03-01

    Complex pixel values for Synthetic Aperture Radar (SAR) images of uniform distributed clutter can be represented as either real/imaginary (also known as I/Q) values, or as Magnitude/Phase values. Generally, these component values are integers with limited number of bits. For clutter energy well below full-scale, Magnitude/Phase offers lower quantization noise than I/Q representation. Further improvement can be had with companding of the Magnitude value.

  4. An EUDET/AIDA Pixel Beam Telescope for Detector Development

    CERN Document Server

    Perrey, Hanno

    2013-01-01

    A high resolution ($\\sigma 2 \\sim \\mu$) beam telescope based on monolithic active pixel sensors (MAPS) was developed within the EUDET collaboration. The telescope consists of six sensor planes using Mimosa26 MAPS with a pixel pitch of $18.4 \\mu$ and thinned down to $50 \\mu$. The excellent resolution, readout rate and DAQ integration capabilities made the telescope a primary test beam tool for many groups including several CERN based experiments. Within the new European detector infrastructure project AIDA the test beam telescope will be further extended in terms of cooling infrastructure, readout speed and precision. In order to provide a system optimized for the different requirements by the user community, a combination of various pixel technologies is foreseen. In this report the design of this even more flexible telescope with three different pixel technologies (TimePix, Mimosa, ATLAS FE-I4) will be presented. First test beam results with the HitOR signal provided by the FE-I4 integrated into the trigger...

  5. An EUDET/AIDA Pixel Beam Telescope for Detector Development

    CERN Document Server

    Rubinskiy, I

    2015-01-01

    A high resolution (σ∼2μm) beam telescope based on monolithic active pixel sensors (MAPS) was developed within the EUDET collaboration. The telescope consists of six monolithic active pixel sensor planes (Mimosa26) with a pixel pitch of 18.4 \\mu m and thinned down to 50 \\mu m. The excellent resolution, readout rate and DAQ integration capabilities made the telescope a primary test beam tool for many groups including several CERN based experiments. Within the European detector infrastructure project AIDA the test beam telescope is being further extended in terms of cooling and powering infrastructure, read-out speed, area of acceptance, and precision. In order to provide a system optimized for the different requirements by the user community a combination of various state-of-the-art pixel technologies is foreseen. Furthermore, new central dead-time-free trigger logic unit (TLU) has been developed to provide LHC-speed response with one-trigger-per-particle operating mode and a synchronous clock for all conn...

  6. CMOS digital pixel sensors: technology and applications

    Science.gov (United States)

    Skorka, Orit; Joseph, Dileepan

    2014-04-01

    CMOS active pixel sensor technology, which is widely used these days for digital imaging, is based on analog pixels. Transition to digital pixel sensors can boost signal-to-noise ratios and enhance image quality, but can increase pixel area to dimensions that are impractical for the high-volume market of consumer electronic devices. There are two main approaches to digital pixel design. The first uses digitization methods that largely rely on photodetector properties and so are unique to imaging. The second is based on adaptation of a classical analog-to-digital converter (ADC) for in-pixel data conversion. Imaging systems for medical, industrial, and security applications are emerging lower-volume markets that can benefit from these in-pixel ADCs. With these applications, larger pixels are typically acceptable, and imaging may be done in invisible spectral bands.

  7. Thin-bedded reservoir analogs in an ancient delta using terrestrial laser scanner and high-resolution ground-based hyperspectral cameras

    Science.gov (United States)

    Snyder, Casey J.; Khan, Shuhab D.; Bhattacharya, Janok P.; Glennie, Craig; Seepersad, Darsel

    2016-08-01

    Ground-based terrestrial laser scanning and hyperspectral sensors were used to image fine-scale heterogeneity in outcrops of prodeltaic heterolithic facies of Parasequence 6 of the Cretaceous Ferron Notom delta in Southern Utah. Previous work shows that Parasequence 6 is an upward coarsening fluvial-dominated, wave-influenced deltaic deposit containing heterolithic thin-bedded facies representing distal delta front and proximal prodelta environments. Primarily, the thin beds have been interpreted as turbidites, storm beds (tempestites), and hyperpycnites. These deposits represent analogs for thin-bedded unconventional pay zones that lie at the margins of conventional deltaic sandstone reservoirs. The terrestrial laser scanner was used to create a centimeter- to decimeter-scale, digital representation of the outcrops in three dimensions. Hyperspectral sensors record electromagnetic radiation reflected off the outcrops in 840 contiguous bands, which were then used to generate a spectral signature for each pixel sampled. The spectral signatures are a function of mineralogy, chemistry, surface alteration, grain-size, and cements, and were used to distinguish thin mudstones from sandstones within an interbedded succession at the base of a deltaic parasequence. Comparison between the spectral signatures recorded from the outcrop and those of reference materials, and with previous facies architecture studies, enables lithofacies to be identified and subsequently accurately mapped. Hyperspectral data are then draped over the terrestrial laser scanner model to generate a spatially-accurate detailed three-dimensional (3D) geologic map of the heterogeneity. Approximately 100 m of outcrop was imaged laterally with the hyperspectral camera and terrestrial laser scanner on the previously mapped distal delta front and prodeltaic facies of Parasequence 6. Bed thickness data, based on measurements made along depositional dip versus strike, show that bed geometries are anisotropic

  8. Mapping Electrical Crosstalk in Pixelated Sensor Arrays

    Science.gov (United States)

    Seshadri, Suresh (Inventor); Cole, David (Inventor); Smith, Roger M (Inventor); Hancock, Bruce R. (Inventor)

    2013-01-01

    The effects of inter pixel capacitance in a pixilated array may be measured by first resetting all pixels in the array to a first voltage, where a first image is read out, followed by resetting only a subset of pixels in the array to a second voltage, where a second image is read out, where the difference in the first and second images provide information about the inter pixel capacitance. Other embodiments are described and claimed.

  9. Mapping Electrical Crosstalk in Pixelated Sensor Arrays

    Science.gov (United States)

    Seshadri, Suresh (Inventor); Cole, David (Inventor); Smith, Roger M. (Inventor); Hancock, Bruce R. (Inventor)

    2017-01-01

    The effects of inter pixel capacitance in a pixilated array may be measured by first resetting all pixels in the array to a first voltage, where a first image is read out, followed by resetting only a subset of pixels in the array to a second voltage, where a second image is read out, where the difference in the first and second images provide information about the inter pixel capacitance. Other embodiments are described and claimed.

  10. CVD diamond pixel detectors for LHC experiments

    Energy Technology Data Exchange (ETDEWEB)

    Wedenig, R.; Adam, W.; Bauer, C.; Berdermann, E.; Bergonzo, P.; Bogani, F.; Borchi, E.; Brambilla, A.; Bruzzi, M.; Colledani, C.; Conway, J.; Dabrowski, W.; Delpierre, P.; Deneuville, A.; Dulinski, W.; Eijk, B. van; Fallou, A.; Fizzotti, F.; Foulon, F.; Friedl, M.; Gan, K.K.; Gheeraert, E.; Grigoriev, E.; Hallewell, G.; Hall-Wilton, R.; Han, S.; Hartjes, F.; Hrubec, J.; Husson, D.; Kagan, H.; Kania, D.; Kaplon, J.; Karl, C.; Kass, R.; Knoepfle, K.T.; Krammer, M.; Logiudice, A.; Lu, R.; Manfredi, P.F.; Manfredotti, C.; Marshall, R.D.; Meier, D.; Mishina, M.; Oh, A.; Pan, L.S.; Palmieri, V.G.; Pernicka, M.; Peitz, A.; Pirollo, S.; Polesello, P.; Pretzl, K.; Procario, M.; Re, V.; Riester, J.L.; Roe, S.; Roff, D.; Rudge, A.; Runolfsson, O.; Russ, J.; Schnetzer, S.; Sciortino, S.; Speziali, V.; Stelzer, H.; Stone, R.; Suter, B.; Tapper, R.J.; Tesarek, R.; Trawick, M.; Trischuk, W.; Vittone, E.; Wagner, A.; Walsh, A.M.; Weilhammer, P.; White, C.; Zeuner, W.; Ziock, H.; Zoeller, M.; Blanquart, L.; Breugnion, P.; Charles, E.; Ciocio, A.; Clemens, J.C.; Dao, K.; Einsweiler, K.; Fasching, D.; Fischer, P.; Joshi, A.; Keil, M.; Klasen, V.; Kleinfelder, S.; Laugier, D.; Meuser, S.; Milgrome, O.; Mouthuy, T.; Richardson, J.; Sinervo, P.; Treis, J.; Wermes, N

    1999-08-01

    This paper reviews the development of CVD diamond pixel detectors. The preparation of the diamond pixel sensors for bump-bonding to the pixel readout electronics for the LHC and the results from beam tests carried out at CERN are described.

  11. CMS has a heart of pixels

    CERN Multimedia

    2003-01-01

    In the immediate vicinity of the collision point, CMS will be equipped with pixel detectors consisting of no fewer than 50 million pixels measuring 150 microns along each side. Each of the pixels, which receive the signal, is connected to its own electronic circuit by a tiny sphere (seen here in the electron microscope image) measuring 15 to 20 microns in diameter.

  12. Integral three-dimensional television with video system using pixel-offset method.

    Science.gov (United States)

    Arai, Jun; Kawakita, Masahiro; Yamashita, Takayuki; Sasaki, Hisayuki; Miura, Masato; Hiura, Hitoshi; Okui, Makoto; Okano, Fumio

    2013-02-11

    Integral three-dimensional (3D) television based on integral imaging requires huge amounts of information. Previously, we constructed an Integral 3D television using Super Hi-Vision (SHV) technology, with 7680 pixels horizontally and 4320 pixels vertically. We report on improved image quality through the development of video system with an equivalent of 8000 scan lines for use with Integral 3D television. We conducted experiments to evaluate the resolution of 3D images using an experimental setup and were able to show that by using the pixel-offset method we have eliminated aliasing produced by full-resolution SHV video equipment. We confirmed that the application of the pixel-offset method to integral 3D television is effective in increasing the resolution of reconstructed images.

  13. An EUDET/AIDA Pixel Beam Telescope for Detector Development

    CERN Document Server

    Rubinskiy, I

    2015-01-01

    Ahigh resolution(σ< 2 μm) beam telescope based on monolithic active pixel sensors (MAPS) was developed within the EUDET collaboration. EUDET was a coordinated detector R&D programme for the future International Linear Collider providing test beam infrastructure to detector R&D groups. The telescope consists of six sensor planes with a pixel pitch of either 18.4 μm or 10 μmand canbe operated insidea solenoidal magnetic fieldofupto1.2T.Ageneral purpose cooling, positioning, data acquisition (DAQ) and offine data analysis tools are available for the users. The excellent resolution, readout rate andDAQintegration capabilities made the telescopea primary beam tests tool also for several CERN based experiments. In this report the performance of the final telescope is presented. The plans for an even more flexible telescope with three differentpixel technologies(ATLASPixel, Mimosa,Timepix) withinthenew European detector infrastructure project AIDA are presented.

  14. Information operator approach applied to the retrieval of the vertical distribution of atmospheric constituents from ground-based high-resolution FTIR measurements

    Directory of Open Access Journals (Sweden)

    C. Senten

    2012-01-01

    Full Text Available The analysis of high spectral resolution Fourier Transform infrared (FTIR solar absorption spectra is an important issue in remote sensing. If this is done carefully, one can obtain information, not only about the total column abundances, but also about the vertical distribution of various constituents in the atmosphere. This work introduces the application of the information operator approach for extracting vertical profile information from ground-based FTIR measurements. The algorithm is implemented and tested within the well-known retrieval code SFIT2, adapting the optimal estimation method such as to take into account only the significant contributions to the solution. In particular, we demonstrate the feasibility of the method in an application to ground-based FTIR spectra taken in the framework of the Network for the Detection of Atmospheric Composition Change (NDACC at Ile de La Réunion (21° S, 55° E. A thorough comparison is made between the original optimal estimation method, Tikhonov regularization and this alternative retrieval algorithm, regarding information content, retrieval robustness and corresponding full error budget evaluation for the target species ozone (O3, nitrous oxide (N2O, methane (CH4, and carbon monoxide (CO. It is shown that the information operator approach performs well and in most cases yields both a better accuracy and stability than the optimal estimation method. Additionally, the information operator approach has the advantage of being less sensitive to the choice of a priori information than the optimal estimation method and Tikhonov regularization. On the other hand, in general the Tikhonov regularization results seem to be slightly better than the optimal estimation method and information operator approach results when it comes to error budgets and column stability.

  15. Dispersed and piled woody residues volumes in coastal Douglas-fir cutblocks determined using high-resolution imagery from a UAV and from ground-based surveys.

    Science.gov (United States)

    Trofymow, J. A.; Gougeon, F.

    2015-12-01

    After forest harvest significant amounts of woody residues are left dispersed on site and some subsequently piled and burned. Quantification of residues is required for estimating C budgets, billable waste, harvest efficiency, bioenergy potential and smoke emissions. Trofymow (et al 2014 CJFR) compared remote sensing methods to ground-based waste and residue survey (WRS) methods for residue piles in 4 cutblocks in the Oyster River (OR) area in coastal BC. Compared to geospatial methods using 15cm orthophotos and LiDAR acquired in 2011 by helicopter, the WRS method underestimated pile wood by 30% to 50% while a USFS volume method overestimated pile wood by 50% if site specific packing ratios were not used. A geospatial method was developed in PCI Geomatica to analyze 2-bit images of logs >15cm diameters to determine dispersed wood residues in OR and compare to WRS methods. Across blocks, geospatial and WRS method wood volumes were correlated (R2=0.69), however volumes were 2.5 times larger for the geospatial vs WRS method. Methods for dispersed residues could not be properly compared as individual WRS plots were not georeferenced, only 12 plots were sampled in total, and low-resolution images poorly resolved logs. Thus, a new study in 2 cutblocks in the Northwest Bay (NWB) area acquired 2cm resolution RGB air-photography in 2014-15 using an Aeryon Sky Ranger UAV prior to and after burn pile construction. A total of 57 dispersed WRS plots and 24 WRS pile or accumulation plots were georeferenced and measured. Stero-pairs were used to generate point-clouds for pile bulk volumes. Images processed to 8-bit grey scale are being analyzed with a revised PCI method that better accounts for log overlaps. WRS methods depend on a good sample of plots and accurate determination of stratum (dispersed, roadside, piles, accumulations) areas. Analysis of NWB blocks shows WRS field methods for stratum area differ by 5-20% from that determined using orthophotos. Plot-level wood

  16. Classification of Urban Aerial Data Based on Pixel Labelling with Deep Convolutional Neural Networks and Logistic Regression

    Science.gov (United States)

    Yao, W.; Poleswki, P.; Krzystek, P.

    2016-06-01

    The recent success of deep convolutional neural networks (CNN) on a large number of applications can be attributed to large amounts of available training data and increasing computing power. In this paper, a semantic pixel labelling scheme for urban areas using multi-resolution CNN and hand-crafted spatial-spectral features of airborne remotely sensed data is presented. Both CNN and hand-crafted features are applied to image/DSM patches to produce per-pixel class probabilities with a L1-norm regularized logistical regression classifier. The evidence theory infers a degree of belief for pixel labelling from different sources to smooth regions by handling the conflicts present in the both classifiers while reducing the uncertainty. The aerial data used in this study were provided by ISPRS as benchmark datasets for 2D semantic labelling tasks in urban areas, which consists of two data sources from LiDAR and color infrared camera. The test sites are parts of a city in Germany which is assumed to consist of typical object classes including impervious surfaces, trees, buildings, low vegetation, vehicles and clutter. The evaluation is based on the computation of pixel-based confusion matrices by random sampling. The performance of the strategy with respect to scene characteristics and method combination strategies is analyzed and discussed. The competitive classification accuracy could be not only explained by the nature of input data sources: e.g. the above-ground height of nDSM highlight the vertical dimension of houses, trees even cars and the nearinfrared spectrum indicates vegetation, but also attributed to decision-level fusion of CNN's texture-based approach with multichannel spatial-spectral hand-crafted features based on the evidence combination theory.

  17. Study of the characteristics of a scintillation array and single pixels for nuclear medicine imaging applications

    Institute of Scientific and Technical Information of China (English)

    ZHU Jie; MA Hong-Guang; MA Wen-Yan; ZENG Hui; WANG Zhao-Min; XU Zi-Zong

    2009-01-01

    By using a pixelized Nal(T1) crystal array coupled to a R2486 PSPMT, the characteristics of the array and of a single pixel, such as the light output, energy resolution, peak-to-valley ratio (P/V) and imaging performance of the detector were studied. The pixel size of the NaI(TI) scintillation pixel array is 2 min×2 mm×5 mm. There are in total 484 pixels in a 22~22 matrix. In the pixel spectrum an average peak-to-valley ratio (P/V) of 16 was obtained. In the image of all the pixels, good values for the Peak-to-Valley ratios could be achieved, namely a mean of 17, a maximum of 45 and the average peak FWHM (the average value of intrinsic spatial resolution) of 2.3 mm. However, the PSPMT non-uniform response and the scintillation pixels array inhomogeneities degrade the imaging performance of the detector.

  18. High-resolution mapping of soil moisture at the field scale using ground-penetrating radar for improving remote sensing data products

    Science.gov (United States)

    Lambot, Sébastien; Mahmoudzadeh, Mohammad Reza; Phuong Tran, Anh; Nottebaere, Martijn; Leonard, Aline; Defourny, Pierre; Neyt, Xavier

    2014-05-01

    Characterizing the spatiotemporal distribution of soil moisture at various scales is essential in agricultural, hydrological, meteorological, and climatological research and applications. Soil moisture determines the boundary condition between the soil and the atmosphere and governs key processes of the hydrological cycle such as infiltration, runoff, root water uptake, evaporation, as well as energy exchanges between the Earth's surface and the atmosphere. In that respect, ground-penetrating radar (GPR) is of particular interest for field-scale soil moisture mapping as soil moisture is highly correlated to its permittivity, which controls radar wave propagation in the soil. Yet, accurate determination of the electrical properties of a medium using GPR requires full-wave inverse modeling, which has remained a major challenge in applied geophysics for many years. We present a new near-field radar modeling approach for wave propagation in layered media. Radar antennas are modeled using an equivalent set of infinitesimal electric dipoles and characteristic, frequency-dependent, global reflection and transmission coefficients. These coefficients determine wave propagation between the radar reference plane, point sources, and field points. The interactions between the antenna and the soil are inherently accounted for. The fields are calculated using three-dimensional Green's functions. We validated the model using both time and frequency domain radars. The radars were mounted on a quad and controlled by a computer for real-time radar and dGPS data acquisition. Several fields were investigated and time-lapse measurements were performed on some of them to analyze temporal stability in soil moisture patterns and the repeatability of the measurements. The results were compared to ground-truths. The proposed technique is presently being applied to improve space-borne remote sensing data products for soil moisture by providing high-resolution observational information that

  19. Making a trillion pixels dance

    Science.gov (United States)

    Singh, Vivek; Hu, Bin; Toh, Kenny; Bollepalli, Srinivas; Wagner, Stephan; Borodovsky, Yan

    2008-03-01

    In June 2007, Intel announced a new pixelated mask technology. This technology was created to address the problem caused by the growing gap between the lithography wavelength and the feature sizes patterned with it. As this gap has increased, the quality of the image has deteriorated. About a decade ago, Optical Proximity Correction (OPC) was introduced to bridge this gap, but as this gap continued to increase, one could not rely on the same basic set of techniques to maintain image quality. The computational lithography group at Intel sought to alleviate this problem by experimenting with additional degrees of freedom within the mask. This paper describes the resulting pixelated mask technology, and some of the computational methods used to create it. The first key element of this technology is a thick mask model. We realized very early in the development that, unlike traditional OPC methods, the pixelated mask would require a very accurate thick mask model. Whereas in the traditional methods, one can use the relatively coarse approximations such as the boundary layer method, use of such techniques resulted not just in incorrect sizing of parts of the pattern, but in whole features missing. We built on top of previously published domain decomposition methods, and incorporated limitations of the mask manufacturing process, to create an accurate thick mask model. Several additional computational techniques were invoked to substantially increase the speed of this method to a point that it was feasible for full chip tapeout. A second key element of the computational scheme was the comprehension of mask manufacturability, including the vital issue of the number of colors in the mask. While it is obvious that use of three or more colors will give the best image, one has to be practical about projecting mask manufacturing capabilities for such a complex mask. To circumvent this serious issue, we eventually settled on a two color mask - comprising plain glass and etched

  20. Shape determination of microcalcifications in simulated digital mammography images with varying pixel size

    Science.gov (United States)

    Ruschin, Mark; Bath, Magnus; Hemdal, Bengt; Tingberg, Anders

    2005-04-01

    The purpose of this work was to study how the pixel size of digital detectors can affect shape determination of microcalcifications in mammography. Screen-film mammograms containing microcalcifications clinically proven to be indicative of malignancy were digitised at 100 lines/mm using a high-resolution Tango drum scanner. Forty microcalcifications were selected to cover an appropriate range of sizes, shapes and contrasts typically found of malignant cases. Based on the measured MTF and NPS of the combined screen-film and scanner system, these digitised images were filtered to simulate images acquired with a square sampling pixel size of 10 μm x 10 μm and a fill factor of one. To simulate images acquired with larger pixel sizes, these finely sampled images were re-binned to yield a range of effective pixel sizes from 20 μm up to 140 μm. An alternative forced-choice (AFC) observer experiment was conducted with eleven observers for this set of digitised microcalcifications to determine how pixel size affects the ability to discriminate shape. It was found that observer score increased with decreasing pixel size down to 60 μm (p<0.01), at which point no significant advantage was obtained by using smaller pixel sizes due to the excessive relative noise-per-pixel. The relative gain in shape discrimination ability at smaller pixel sizes was larger for microcalcifications that were smaller than 500 μm and circular.

  1. Advances in monitoring dynamic hydrologic conditions in the vadose zone through automated high-resolution ground-penetrating radar imaging and analysis

    Science.gov (United States)

    Mangel, Adam R.

    This body of research focuses on resolving physical and hydrological heterogeneities in the subsurface with ground-penetrating radar (GPR). Essentially, there are two facets of this research centered on the goal of improving the collective understanding of unsaturated flow processes: i) modifications to commercially available equipment to optimize hydrologic value of the data and ii) the development of novel methods for data interpretation and analysis in a hydrologic context given the increased hydrologic value of the data. Regarding modifications to equipment, automation of GPR data collection substantially enhances our ability to measure changes in the hydrologic state of the subsurface at high spatial and temporal resolution (Chapter 1). Additionally, automated collection shows promise for quick high-resolution mapping of dangerous subsurface targets, like unexploded ordinance, that may have alternate signals depending on the hydrologic environment (Chapter 5). Regarding novel methods for data inversion, dispersive GPR data collected during infiltration can constrain important information about the local 1D distribution of water in waveguide layers (Chapters 2 and 3), however, more data is required for reliably analyzing complicated patterns produced by the wetting of the soil. In this regard, data collected in 2D and 3D geometries can further illustrate evidence of heterogeneous flow, while maintaining the content for resolving wave velocities and therefore, water content. This enables the use of algorithms like reflection tomography, which show the ability of the GPR data to independently resolve water content distribution in homogeneous soils (Chapter 5). In conclusion, automation enables the non-invasive study of highly dynamic hydrologic processes by providing the high resolution data required to interpret and resolve spatial and temporal wetting patterns associated with heterogeneous flow. By automating the data collection, it also allows for the novel

  2. Optimization of linear-logarithmic CMOS image sensor using a photogate and a cascode MOSFET for reducing pixel response variation

    Science.gov (United States)

    Bae, Myunghan; Choi, Byoung-Soo; Kim, Sang-Hwan; Lee, Jimin; Oh, Chang-Woo; Shin, Jang-Kyoo

    2017-02-01

    Recently, CMOS image sensors (CISs) have become more and more complex because they require high-performances such as wide dynamic range, low-noise, high-speed operation, high-resolution and so on. First of all, wide dynamic range (WDR) is the first requirement for high-performance CIS. Several techniques have been proposed to improve the dynamic range. Although logarithmic pixel can achieve wide dynamic range, it leads to a poor signal-to-noise ratio due to small output swings. Furthermore, the fixed pattern noise of logarithmic pixel is significantly greater compared with other CISs. In this paper, we propose an optimized linear-logarithmic pixel. Compared to a conventional 3-transistor active pixel sensor structure, the proposed linear-logarithmic pixel is using a photogate and a cascode MOSFET in addition. The photogate which is surrounding a photodiode carries out change of sensitivity in the linear response and thus increases the dynamic range. The logarithmic response is caused by a cascode MOSFET. Although the dynamic range of the pixel has been improved, output curves of each pixel were not uniform. In general, as the number of devices increases in the pixel, pixel response variation is more pronounced. Hence, we optimized the linear-logarithmic pixel structure to minimize the pixel response variation. We applied a hard reset method and an optimized cascode MOSFET to the proposed pixel for reducing pixel response variation. Unlike the conventional reset operation, a hard reset using a p-type MOSFET fixes the voltage of each pixel to the same voltage. This reduces non-uniformity of the response in the linear response. The optimized cascode MOSFET achieves less variation in the logarithmic response. We have verified that the optimized pixel shows more uniform response than the conventional pixel, by both simulation and experiment.

  3. High Resolution ground penetrating radar (GPR) measurements at the laboratory scale to model porosity and permeability in the Miami Limestone in South Florida.

    Science.gov (United States)

    Mount, G. J.; Comas, X.

    2015-12-01

    Subsurface water flow within the Biscayne aquifer is controlled by the heterogeneous distribution of porosity and permeability in the karst Miami Limestone and the presence of numerous dissolution and mega-porous features. The dissolution features and other high porosity areas can create preferential flow paths and direct recharge to the aquifer, which may not be accurately conceptualized in groundwater flow models. As hydrologic conditions are undergoing restoration in the Everglades, understanding the distribution of these high porosity areas within the subsurface would create a better understanding of subsurface flow. This research utilizes ground penetrating radar to estimate the spatial variability of porosity and dielectric permittivity of the Miami Limestone at centimeter scale resolution at the laboratory scale. High frequency GPR antennas were used to measure changes in electromagnetic wave velocity through limestone samples under varying volumetric water contents. The Complex Refractive Index Model (CRIM) was then applied in order to estimate porosity and dielectric permittivity of the solid phase of the limestone. Porosity estimates ranged from 45.2-66.0% from the CRIM model and correspond well with estimates of porosity from analytical and digital image techniques. Dielectric permittivity values of the limestone solid phase ranged from 7.0 and 13.0, which are similar to values in the literature. This research demonstrates the ability of GPR to identify the cm scale spatial variability of aquifer properties that influence subsurface water flow which could have implications for groundwater flow models in the Biscayne and potentially other shallow karst aquifers.

  4. High-resolution computed tomography to differentiate chronic diffuse interstitial lung diseases with predominant ground-glass pattern using logical analysis of data

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Sophie Grivaud; Brauner, Michel W.; Rety, Frederique [Universite Paris 13, Assistance Publique-Hopitaux de Paris, Hopital Avicenne, UPRES EA 2363, Department of Radiology, Bobigny (France); Kronek, Louis-Philippe; Brauner, Nadia [Universite Joseph Fourier, Laboratoire G-SCOP, Grenoble (France); Valeyre, Dominique; Nunes, Hilario [Universite Paris 13, Assistance Publique-Hopitaux de Paris, Hopital Avicenne, UPRES EA 2363, Department of Pneumology, Bobigny (France); Brillet, Pierre-Yves [Universite Paris 13, Assistance Publique-Hopitaux de Paris, Hopital Avicenne, UPRES EA 2363, Department of Radiology, Bobigny (France); Hopital Avicenne, Service de Radiologie, Bobigny Cedex (France)

    2010-06-15

    We evaluated the performance of high-resolution computed tomography (HRCT) to differentiate chronic diffuse interstitial lung diseases (CDILD) with predominant ground-glass pattern by using logical analysis of data (LAD). A total of 162 patients were classified into seven categories: sarcoidosis (n = 38), connective tissue disease (n = 32), hypersensitivity pneumonitis (n = 18), drug-induced lung disease (n = 15), alveolar proteinosis (n = 12), idiopathic non-specific interstitial pneumonia (n = 10) and miscellaneous (n = 37). First, 40 CT attributes were investigated by the LAD to build up patterns characterising a category. From the association of patterns, LAD determined models specific to each CDILD. Second, data were recomputed by adding eight clinical attributes to the analysis. The 20 x 5 cross-folding method was used for validation. Models could be individualised for sarcoidosis, hypersensitivity pneumonitis, connective tissue disease and alveolar proteinosis. An additional model was individualised for drug-induced lung disease by adding clinical data. No model was demonstrated for idiopathic non-specific interstitial pneumonia and the miscellaneous category. The results showed that HRCT had a good sensitivity ({>=}64%) and specificity ({>=}78%) and a high negative predictive value ({>=}93%) for diseases with a model. Higher sensitivity ({>=}78%) and specificity ({>=}89%) were achieved by adding clinical data. The diagnostic performance of HRCT is high and can be increased by adding clinical data. (orig.)

  5. Serial powering of pixel modules

    CERN Document Server

    Stockmanns, Tobias; Hügging, Fabian Georg; Peric, I; Runólfsson, O; Wermes, Norbert

    2003-01-01

    Modern pixel detectors for the next generation of high-energy collider experiments like LHC use readout electronics in deep sub- micron technology. Chips in this technology need a low supply voltage of 2-2.5 V alongside high current consumption to achieve the desired performance. The high supply current leads to significant voltage drops in the long and low mass supply cables so that voltage fluctuations at the chips are induced, when the supply current changes. This problem scales with the number of modules when connected in parallel to the power supplies. An alternative powering scheme connects several modules in series resulting in a higher supply voltage but a lower current consumption of the chain and therefore a much lower voltage drop in the cables. In addition the amount of cables needed to supply the detector is vastly reduced. The concept and features of serial powering are presented and studies of the implementation of this technology as an alternative for the ATLAS pixel detector are shown. In par...

  6. Proceedings of PIXEL98 -- International pixel detector workshop

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, D.F.; Kwan, S. [eds.

    1998-08-01

    Experiments around the globe face new challenges of more precision in the face of higher interaction rates, greater track densities, and higher radiation doses, as they look for rarer and rarer processes, leading many to incorporate pixelated solid-state detectors into their plans. The highest-readout rate devices require new technologies for implementation. This workshop reviewed recent, significant progress in meeting these technical challenges. Participants presented many new results; many of them from the weeks--even days--just before the workshop. Brand new at this workshop were results on cryogenic operation of radiation-damaged silicon detectors (dubbed the Lazarus effect). Other new work included a diamond sensor with 280-micron collection distance; new results on breakdown in p-type silicon detectors; testing of the latest versions of read-out chip and interconnection designs; and the radiation hardness of deep-submicron processes.

  7. Modeling Inter-Pixel Crosstalk in Teledyne Imaging Sensors H4RG Detectors

    CERN Document Server

    Dudik, R P; Dorland, B N; Veillette, D; Waczynski, A; Lane, B; Loose, M; Kan, E; Waterman, J; Pravdo, S

    2012-01-01

    CMOS-hybrid arrays have recently surfaced as competitive optical detectors for use in ground- and space-based astronomy. One source of error in these detectors that does not appear in more traditional CCD arrays is the inter-pixel capacitance component of crosstalk. In this paper we use a single pixel reset method to model inter-pixel capacitance (IPC). We combine this IPC model with a model for charge diffusion to estimate the total crosstalk on H4RG arrays. Finally, we compare our model results to Fe55 data obtained using an astrometric camera built to test the H4RG-B0 generation detectors.

  8. Neural network based cluster creation in the ATLAS silicon Pixel Detector

    CERN Document Server

    Andreazza, A; The ATLAS collaboration

    2013-01-01

    The read-out from individual pixels on planar semi-conductor sensors are grouped into clusters to reconstruct the location where a charged particle passed through the sensor. The resolution given by individual pixel sizes is significantly improved by using the information from the charge sharing between pixels. Such analog cluster creation techniques have been used by the ATLAS experiment for many years to obtain an excellent performance. However, in dense environments, such as those inside high-energy jets, clusters have an increased probability of merging the charge deposited by multiple particles. Recently, a neural network based algorithm which estimates both the cluster position and whether a cluster should be split has been developed for the ATLAS Pixel Detector. The algorithm significantly reduces ambiguities in the assignment of pixel detector measurement to tracks within jets and improves the position accuracy with respect to standard interpolation techniques by taking into account the 2-dimensional ...

  9. Neural network based cluster creation in the ATLAS silicon Pixel Detector

    CERN Document Server

    Perez Cavalcanti, T; The ATLAS collaboration

    2012-01-01

    The hit signals read out from pixels on planar semi-conductor sensors are grouped into clusters, to reconstruct the location where a charged particle passed through. The resolution of the individual pixel sizes can be improved significantly using the information from the cluster of adjacent pixels. Such analog cluster creation techniques have been used by the ATLAS experiment for many years giving an excellent performance. However, in dense environments, such as those inside high-energy jets, is likely that the charge deposited by two or more close-by tracks merges into one single cluster. A new pattern recognition algorithm based on neural network methods has been developed for the ATLAS Pixel Detector. This can identify the shared clusters, split them if necessary, and estimate the positions of all particles traversing the cluster. The algorithm significantly reduces ambiguities in the assignment of pixel detector measurements to tracks within jets, and improves the positional accuracy with respect to stand...

  10. Electrical characterization of irradiated prototype silicon pixel sensors for BTeV

    Energy Technology Data Exchange (ETDEWEB)

    Maria Rita Coluccia et al.

    2002-11-13

    The pixel detector in the BteV experiment at the Tevatron (Fermi Laboratory) is an important detector component for high-resolution tracking and vertex identification. For this task the hybrid pixel detector has to work in a very harsh radiation environment with up to 10{sup 14} minimum ionizing particles/cm{sup 2}/year. Radiation hardness of prototype n{sup +}/n/p{sup +} silicon pixel sensors has been investigated. We present Electrical characterization curves for irradiated prototype n{sup +}/n/p{sup +} sensors, intended for use in the BTeV experiment. We tested pixel sensors from various vendors and with two pixel isolation techniques: p-stop and p-spray. Results are based on irradiation with 200 MeV protons up to 6 x 10{sup 14} protons/cm{sup 2}.

  11. A Global-Scale Image Lossless Compression Method Based on QTM Pixels

    Institute of Scientific and Technical Information of China (English)

    SUN Wen-bin; ZHAO Xue-sheng

    2006-01-01

    In this paper, a new predictive model, adapted to QTM (Quaternary Triangular Mesh) pixel compression, is introduced. Our approach starts with the principles of proposed predictive models based on available QTM neighbor pixels. An algorithm of ascertaining available QTM neighbors is also proposed. Then, the method for reducing space complexities in the procedure of predicting QTM pixel values is presented. Next, the structure for storing compressed QTM pixel is proposed. In the end, the experiment on comparing compression ratio of this method with other methods is carried out by using three wave bands data of 1 km resolution of NOAA images in China. The results indicate that: 1) the compression method performs better than any other, such as Run Length Coding, Arithmetic Coding, Huffman Coding, etc; 2) the average size of compressed three wave band data based on the neighbor QTM pixel predictive model is 31.58% of the origin space requirements and 67.5% of Arithmetic Coding without predictive model.

  12. Silicon Avalanche Pixel Sensor for High Precision Tracking

    CERN Document Server

    D'Ascenzo, N; Moon, C S; Morsani, F; Ratti, L; Saveliev, V; Navarro, A Savoy; Xie, Q

    2013-01-01

    The development of an innovative position sensitive pixelated sensor to detect and measure with high precision the coordinates of the ionizing particles is proposed. The silicon avalanche pixel sensors (APiX) is based on the vertical integration of avalanche pixels connected in pairs and operated in coincidence in fully digital mode and with the processing electronics embedded on the chip. The APiX sensor addresses the need to minimize the material budget and related multiple scattering effects in tracking systems requiring a high spatial resolution in the presence of a large occupancy. The expected operation of the new sensor features: low noise, low power consumption and suitable radiation tolerance. The APiX device provides on-chip digital information on the position of the coordinate of the impinging charged particle and can be seen as the building block of a modular system of pixelated arrays, implementing a sparsified readout. The technological challenges are the 3D integration of the device under CMOS ...

  13. The NUC and blind pixel eliminating in the DTDI application

    Science.gov (United States)

    Su, Xiao Feng; Chen, Fan Sheng; Pan, Sheng Da; Gong, Xue Yi; Dong, Yu Cui

    2013-12-01

    AS infrared CMOS Digital TDI (Time Delay and integrate) has a simple structure, excellent performance and flexible operation, it has been used in more and more applications. Because of the limitation of the Production process level, the plane array of the infrared detector has a large NU (non-uniformity) and a certain blind pixel rate. Both of the two will raise the noise and lead to the TDI works not very well. In this paper, for the impact of the system performance, the most important elements are analyzed, which are the NU of the optical system, the NU of the Plane array and the blind pixel in the Plane array. Here a reasonable algorithm which considers the background removal and the linear response model of the infrared detector is used to do the NUC (Non-uniformity correction) process, when the infrared detector array is used as a Digital TDI. In order to eliminate the impact of the blind pixel, the concept of surplus pixel method is introduced in, through the method, the SNR (signal to noise ratio) can be improved and the spatial and temporal resolution will not be changed. Finally we use a MWIR (Medium Ware Infrared) detector to do the experiment and the result proves the effectiveness of the method.

  14. Electron imaging with Medipix2 hybrid pixel detector

    CERN Document Server

    McMullan, G; Chen, S; Henderson, R; Llopart, X; Summerfield, C; Tlustos, L; Faruqi, A R

    2007-01-01

    The electron imaging performance of Medipix2 is described. Medipix2 is a hybrid pixel detector composed of two layers. It has a sensor layer and a layer of readout electronics, in which each 55 μm×55 μm pixel has upper and lower energy discrimination and MHz rate counting. The sensor layer consists of a 300 μm slab of pixellated monolithic silicon and this is bonded to the readout chip. Experimental measurement of the detective quantum efficiency, DQE(0) at 120 keV shows that it can reach 85% independent of electron exposure, since the detector has zero noise, and the DQE(Nyquist) can reach 35% of that expected for a perfect detector (4/π2). Experimental measurement of the modulation transfer function (MTF) at Nyquist resolution for 120 keV electrons using a 60 keV lower energy threshold, yields a value that is 50% of that expected for a perfect detector (2/π). Finally, Monte Carlo simulations of electron tracks and energy deposited in adjacent pixels have been performed and used to calculate expected v...

  15. Study of performance of small gamma camera consisting of crystal pixel array and position sensitive photomultiplier tube

    Institute of Scientific and Technical Information of China (English)

    ZHU Jie; LIU Shi-Tao; LEI Xiao-Wen; YAN Tian-Xin; XU Zi-Zong; WANG Zhao-Min

    2005-01-01

    The performance of gamma camera with NaI(T1) array coupled with position sensitive photomultiplier tube (PSPMT) R2486 has been studied. The pixel size of NaI(T1) crystal is 2mm×2mm and the overall dimension of the array is 48.2mm×48.2mm×5mm. There are 484 pixels in a 22×22 matrix. Because each pixel can produce a much focused light spot and restrict the spread of photons, position resolution of the gamma camera is mainly determined by pixel size. It is shown that crystal array pixel can reduce shrinkage effect and improve intrinsic position resolution greatly via restricting the spread of photons. Experimental results demonstrate that its position resolution and linearity are much improved comparing with the gamma camera using planar crystals coupled with PSPMT.

  16. ATLAS Pixel Opto-Electronics

    CERN Document Server

    Arms, K E; Gan, K K; Holder, M; Jackson, P; Johnson, M; Kagan, H; Kass, R; Rahimi, A M; Roggenbuck, A; Rush, C; Schade, P; Smith, S; Ter-Antonian, R; Ziolkowski, M; Zoeller, M M

    2005-01-01

    We have developed two radiation-hard ASICs for optical data transmission in the ATLAS pixel detector at the LHC at CERN: a driver chip for a Vertical Cavity Surface Emitting Laser (VCSEL) diode for 80 Mbit/s data transmission from the detector, and a Bi-Phase Mark decoder chip to recover the control data and 40 MHz clock received optically by a PIN diode. We have successfully implemented both ASICs in 0.25 micron CMOS technology using enclosed layout transistors and guard rings for increased radiation hardness. We present results of the performance of these chips, including irradiation with 24 GeV protons up to 61 Mrad (2.3 x 10e15 p/cm^2).

  17. Signal modeling of charge sharing effect in simple pixelated CdZnTe detector

    Science.gov (United States)

    Kim, Jae Cheon; Kaye, William R.; He, Zhong

    2014-05-01

    In order to study the energy resolution degradation in 3D position-sensitive pixelated CdZnTe (CZT) detectors, a detailed detector system modeling package has been developed and used to analyze the detector performance. A 20 × 20 × 15 mm3 CZT crystal with an 11 × 11 simple-pixel anode array and a 1.72 mm pixel pitch was modeled. The VAS UM/TAT4 Application Specific Integrated Circuitry (ASIC) was used for signal read-out. Components of the simulation package include gamma-ray interactions with the CZT crystal, charge induction, electronic noise, pulse shaping, and ASIC triggering procedures. The charge induction model considers charge drift, trapping, diffusion, and sharing between pixels. This system model is used to determine the effects of electron cloud sharing, weighting potential non-uniformity, and weighting potential cross-talk which produce non-uniform signal responses for different gamma-ray interaction positions and ultimately degrade energy resolution. The effect of the decreased weighting potential underneath the gap between pixels on the total pulse amplitude of events has been studied. The transient signals induced by electron clouds collected near the gap between pixels may generate false signals, and the measured amplitude can be even greater than the photopeak. As the number of pixels that collect charge increases, the probability of side-neighbor events due to charge sharing significantly increases. If side-neighbor events are not corrected appropriately, the energy resolution of pixelated CZT detectors in multiple-pixel events degrades rapidly.

  18. Signal modeling of charge sharing effect in simple pixelated CdZnTe detector

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jae C.; Kaye, William R.; He, Zhong [University of Michigan, Ann Arbor, MI (United States)

    2014-05-15

    In order to study the energy resolution degradation in 3D position-sensitive pixelated CdZnTe (CZT) detectors, a detailed detector system modeling package has been developed and used to analyze the detector performance. A 20 x 20 x 15 mm{sup 3} CZT crystal with an 11 x 11 simple-pixel anode array and a 1.72 mm pixel pitch was modeled. The VAS UM/TAT4 Application Specific Integrated Circuitry (ASIC) was used for signal read-out. Components of the simulation package include gamma-ray interactions with the CZT crystal, charge induction, electronic noise, pulse shaping, and ASIC triggering procedures. The charge induction model considers charge drift, trapping, diffusion, and sharing between pixels. This system model is used to determine the effects of electron cloud sharing, weighting potential non-uniformity, and weighting potential cross-talk which produce non-uniform signal responses for different gamma-ray interaction positions and ultimately degrade energy resolution. The effect of the decreased weighting potential underneath the gap between pixels on the total pulse amplitude of events has been studied. The transient signals induced by electron clouds collected near the gap between pixels may generate false signals, and the measured amplitude can be even greater than the photopeak. As the number of pixels that collect charge increases, the probability of side-neighbor events due to charge sharing significantly increases. If side-neighbor events are not corrected appropriately, the energy resolution of pixelated CZT detectors in multiple-pixel events degrades rapidly.

  19. Detection of a large sample of γ Doradus stars from Kepler space photometry and high-resolution ground-based spectroscopy

    Science.gov (United States)

    Tkachenko, A.; Aerts, C.; Yakushechkin, A.; Debosscher, J.; Degroote, P.; Bloemen, S.; Pápics, P. I.; de Vries, B. L.; Lombaert, R.; Hrudkova, M.; Frémat, Y.; Raskin, G.; Van Winckel, H.

    2013-08-01

    Context. The launches of the MOST, CoRoT, and Kepler missions opened up a new era in asteroseismology, the study of stellar interiors via interpretation of pulsation patterns observed at the surfaces of large groups of stars. These space missions deliver a huge amount of high-quality photometric data suitable to study numerous pulsating stars. Aims: Our ultimate goal is a detection and analysis of an extended sample of γ Dor-type pulsating stars with the aim to search for observational evidence of non-uniform period spacings and rotational splittings of gravity modes in main-sequence stars typically twice as massive as the Sun. This kind of diagnostic can be used to deduce the internal rotation law and to estimate the amount of rotational mixing in the near core regions. Methods: We applied an automated supervised photometric classification method to select a sample of 69 Gamma Doradus (γ Dor) candidate stars. We used an advanced method to extract the Kepler light curves from the pixel data information using custom masks. For 36 of the stars, we obtained high-resolution spectroscopy with the HERMES spectrograph installed at the Mercator telescope. The spectroscopic data are analysed to determine the fundamental parameters like Teff, log g, vsini, and [M/H]. Results: We find that all stars for which spectroscopic estimates of Teff and log g are available fall into the region of the HR diagram, where the γ Dor and δ Sct instability strips overlap. The stars cluster in a 700 K window in effective temperature; log g measurements suggest luminosity class IV-V, i.e. sub-giant or main-sequence stars. From the Kepler photometry, we identify 45 γ Dor-type pulsators, 14 γ Dor/δ Sct hybrids, and 10 stars, which are classified as "possibly γ Dor/δ Sct hybrid pulsators". We find a clear correlation between the spectroscopically derived vsini and the frequencies of independent pulsation modes. Conclusions: We have shown that our photometric classification based on the

  20. Pixel readout chip for the ATLAS experiment

    CERN Document Server

    Ackers, M; Blanquart, L; Bonzom, V; Comes, G; Fischer, P; Keil, M; Kühl, T; Meuser, S; Delpierre, P A; Treis, J; Raith, B A; Wermes, N

    1999-01-01

    Pixel detectors with a high granularity and a very large number of sensitive elements (cells) are a very recent development used for high precision particle detection. At the Large Hadron Collider LHC at CERN (Geneva) a pixel detector with 1.4*10/sup 8/ individual pixel cells is developed for the ATLAS detector. The concept is a hybrid detector. Consisting of a pixel sensor connected to a pixel electronics chip by bump and flip chip technology in one-to-one cell correspondence. The development and prototype results of the pixel front end chip are presented together with the physical and technical requirements to be met at LHC. Lab measurements are reported. (6 refs).

  1. Advanced pixel architectures for scientific image sensors

    CERN Document Server

    Coath, R; Godbeer, A; Wilson, M; Turchetta, R

    2009-01-01

    We present recent developments from two projects targeting advanced pixel architectures for scientific applications. Results are reported from FORTIS, a sensor demonstrating variants on a 4T pixel architecture. The variants include differences in pixel and diode size, the in-pixel source follower transistor size and the capacitance of the readout node to optimise for low noise and sensitivity to small amounts of charge. Results are also reported from TPAC, a complex pixel architecture with ~160 transistors per pixel. Both sensors were manufactured in the 0.18μm INMAPS process, which includes a special deep p-well layer and fabrication on a high resistivity epitaxial layer for improved charge collection efficiency.

  2. Dead pixel replacement in LWIR microgrid polarimeters.

    Science.gov (United States)

    Ratliff, Bradley M; Tyo, J Scott; Boger, James K; Black, Wiley T; Bowers, David L; Fetrow, Matthew P

    2007-06-11

    LWIR imaging arrays are often affected by nonresponsive pixels, or "dead pixels." These dead pixels can severely degrade the quality of imagery and often have to be replaced before subsequent image processing and display of the imagery data. For LWIR arrays that are integrated with arrays of micropolarizers, the problem of dead pixels is amplified. Conventional dead pixel replacement (DPR) strategies cannot be employed since neighboring pixels are of different polarizations. In this paper we present two DPR schemes. The first is a modified nearest-neighbor replacement method. The second is a method based on redundancy in the polarization measurements.We find that the redundancy-based DPR scheme provides an order-of-magnitude better performance for typical LWIR polarimetric data.

  3. A method for precise charge reconstruction with pixel detectors using binary hit information

    CERN Document Server

    Pohl, David-Leon; Hemperek, Tomasz; Hügging, Fabian; Wermes, Norbert

    2014-01-01

    A method is presented to precisely reconstruct charge spectra with pixel detectors using binary hit information of individual pixels. The method is independent of the charge information provided by the readout circuitry and has a resolution mainly limited by the electronic noise. It relies on the ability to change the detection threshold in small steps while counting hits from a particle source. The errors are addressed and the performance of the method is shown based on measurements with the ATLAS pixel chip FE-I4 bump bonded to a 230 {\\mu}m 3D-silicon sensor. Charge spectra from radioactive sources and from electron beams are presented serving as examples. It is demonstrated that a charge resolution ({\\sigma}<200 e) close to the electronic noise of the ATLAS FE-I4 pixel chip can be achieved.

  4. Modelling and 3D optimisation of CdTe pixels detector array geometry - Extension to small pixels

    CERN Document Server

    Zumbiehl, A; Fougeres, P; Koebel, J M; Regal, R; Rit, C; Ayoub, M; Siffert, P

    2001-01-01

    CdTe and CdZnTe pixel detectors offer great interest for many applications, especially for medical and industrial imaging. Up to now, the material, generally, used and investigated for pixel arrays was CZT (Hamel et al., IEEE Trans. Nucl. Sci. 43 (3) (1996) 1422; Barrett et al., Phys. Rev. Lett. 75 (1) (1995) 156; Bennett et al., Nucl. Instr. and Meth. A 392 (1997) 260; Eskin et al., J. Appl. Phys. 85 (2) (1999) 647; Brunett et al., J. Appl. Phys. 86 (7) (1999) 3926; Luke, Nucl. Instr. and Meth. A 380 (1996) 232), but cadmium telluride can also be an appropriate choice, as shown here. However, we clearly demonstrate here that the optimal pixel configuration is highly dependent on the electrical transport properties of the material. Depending on the field of primary interest, either energy resolution or counting rate efficiency in the photopeak, the geometry for each case has to be optimised. For that purpose, we have developed a calculation of the signal induced onto the pixel. Two distinct parts are used: af...

  5. What if the Earth is Not Flat? Cross-Scale Analysis of Sub-Pixel Variations in Digital Elevation Models

    Science.gov (United States)

    Ghandehari, M.; P Buttenfield, B.; J Q Farmer, C.

    2016-12-01

    Digital terrain models guide scientists and planners in multiple ways and have fundamental impacts on society, safety and resource management. Terrain is currently modeled in a grid of pixels, assuming that elevation values are constant within any single pixel of a Digital Elevation Model (DEM) (`rigid pixel' paradigm). The assumption of rigid pixels generates basic spatial measurements that are in fact imprecise. In truth, terrain can bend, twist and undulate within each pixel, more similar to a continuous and flexible fabric. For localized areas or for very small pixel sizes, the amount of imprecision is insignificant, but can increase with larger pixel size and/or across regional or global expanses, as in the case with models of climate change, sea level rise, and other modeling applications, where pixels can span dozens to hundreds of kilometers. This research examines the sensitivity of surface adjustment to a progression of spatial resolutions (10, 30, 100, and 1000 meter DEMs), validating sub-pixel variations that can be directly measured from finer resolution LiDAR data. Tests will interpolate the elevation of 1,000 georeferenced random points using different methods (weighted average, as well as bi-linear, bi-quadratic, and bi-cubic polynomial fitting) and different contiguity configurations (incorporating first and second order neighbors), and conflate each resolution against a finer resolution LiDAR data benchmark. Additional tests will compute Root Mean Square Error (RMSE) between DEM and LiDAR to assess differences in various methods and resolutions. The paper will present results of the benchmark comparison for a number of study areas characterized by varying degrees of terrain roughness, along with guidelines for determining what terrain conditions and spatial resolutions dramatically modify elevation estimates, and which elevation estimation method(s) are more reliable for particular terrain conditions and particular pixel sizes.

  6. Mapping Above-Ground Biomass of Winter Oilseed Rape Using High Spatial Resolution Satellite Data at Parcel Scale under Waterlogging Conditions

    Directory of Open Access Journals (Sweden)

    Jiahui Han

    2017-03-01

    Full Text Available Oilseed rape (Brassica napus L. is one of the three most important oil crops in China, and is regarded as a drought-tolerant oilseed crop. However, it is commonly sensitive to waterlogging, which usually refers to an adverse environment that limits crop development. Moreover, crop growth and soil irrigation can be monitored at a regional level using remote sensing data. High spatial resolution optical satellite sensors are very useful to capture and resist unfavorable field conditions at the sub-field scale. In this study, four different optical sensors, i.e., Pleiades-1A, Worldview-2, Worldview-3, and SPOT-6, were used to estimate the dry above-ground biomass (AGB of oilseed rape and track the seasonal growth dynamics. In addition, three different soil water content field experiments were carried out at different oilseed rape growth stages from November 2014 to May 2015 in Northern Zhejiang province, China. As a significant indicator of crop productivity, AGB was measured during the seasonal growth stages of the oilseed rape at the experimental plots. Several representative vegetation indices (VIs obtained from multiple satellite sensors were compared with the simultaneously-collected oilseed rape AGB. Results showed that the estimation model using the normalized difference vegetation index (NDVI with a power regression model performed best through the seasonal growth dynamics, with the highest coefficient of determination (R2 = 0.77, the smallest root mean square error (RMSE = 104.64 g/m2, and the relative RMSE (rRMSE = 21%. It is concluded that the use of selected VIs and high spatial multiple satellite data can significantly estimate AGB during the winter oilseed rape growth stages, and can be applied to map the variability of winter oilseed rape at the sub-field level under different waterlogging conditions, which is very promising in the application of agricultural irrigation and precision agriculture.

  7. Performance of silicon pixel detectors at small track incidence angles for the ATLAS Inner Tracker upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Viel, Simon, E-mail: sviel@lbl.gov [Physics Division, Lawrence Berkeley National Laboratory and University of California, Berkeley, CA, United States of America (United States); Banerjee, Swagato [Department of Physics, University of Wisconsin, Madison, WI, United States of America (United States); Brandt, Gerhard; Carney, Rebecca; Garcia-Sciveres, Maurice [Physics Division, Lawrence Berkeley National Laboratory and University of California, Berkeley, CA, United States of America (United States); Hard, Andrew Straiton; Kaplan, Laser Seymour; Kashif, Lashkar [Department of Physics, University of Wisconsin, Madison, WI, United States of America (United States); Pranko, Aliaksandr [Physics Division, Lawrence Berkeley National Laboratory and University of California, Berkeley, CA, United States of America (United States); Rieger, Julia [Physics Division, Lawrence Berkeley National Laboratory and University of California, Berkeley, CA, United States of America (United States); II Physikalisches Institut, Georg-August-Universität, Göttingen (Germany); Wolf, Julian [Physics Division, Lawrence Berkeley National Laboratory and University of California, Berkeley, CA, United States of America (United States); Wu, Sau Lan; Yang, Hongtao [Department of Physics, University of Wisconsin, Madison, WI, United States of America (United States)

    2016-09-21

    In order to enable the ATLAS experiment to successfully track charged particles produced in high-energy collisions at the High-Luminosity Large Hadron Collider, the current ATLAS Inner Detector will be replaced by the Inner Tracker (ITk), entirely composed of silicon pixel and strip detectors. An extension of the tracking coverage of the ITk to very forward pseudorapidity values is proposed, using pixel modules placed in a long cylindrical layer around the beam pipe. The measurement of long pixel clusters, detected when charged particles cross the silicon sensor at small incidence angles, has potential to significantly improve the tracking efficiency, fake track rejection, and resolution of the ITk in the very forward region. The performance of state-of-the-art pixel modules at small track incidence angles is studied using test beam data collected at SLAC and CERN. - Highlights: • Extended inner pixel barrel layers are proposed for the ATLAS ITk upgrade. • Test beam results at small track incidence angles validate this ATLAS ITk design. • Long pixel clusters are reconstructed with high efficiency at low threshold values. • Excellent angular resolution is achieved using pixel cluster length information.

  8. A Beam Monitor Using Silicon Pixel Sensors for Hadron Therapy

    CERN Document Server

    Wang, Zhen; Fan, Yan; Liu, Jun; Sun, Xiangming; Wang, Dong; Kang, Huili; Sun, Daming; Yang, Ping; Pei, Hua; Huang, Guangming; Xu, Nu; Gao, Chaosong; Xiao, Le

    2016-01-01

    We report the design and test results of a beam monitor developed for online monitoring in hadron therapy. The beam monitor uses eight silicon pixel sensors, \\textit{Topmetal-${II}^-$}, as the anode array. \\textit{Topmetal-${II}^-$} is a charge sensor designed in a CMOS 0.35 $\\mu$m technology. Each \\textit{Topmetal-${II}^-$} sensor has $72\\times72$ pixels. Each pixel size is about $83\\times83$ $\\mu$m$^2$. In our design the beam passes through the beam monitor without hitting the electrodes, making the beam monitor especially suitable for monitoring heavy ion beams. This design also reduces radiation damage to the beam monitor itself. The beam monitor is tested at the Heavy Ion Research Facility in Lanzhou (HIRFL) which provides a carbon ion beam. Results indicate that the beam monitor can measure position, incident angle and intensity of the beam with a position resolution better than 20 $\\mu$m, angular resolution about 0.5$^\\circ$ and intensity statistical accuracy better than 2$\\%$.

  9. A beam monitor using silicon pixel sensors for hadron therapy

    Science.gov (United States)

    Wang, Zhen; Zou, Shuguang; Fan, Yan; Liu, Jun; Sun, Xiangming; Wang, Dong; Kang, Huili; Sun, Daming; Yang, Ping; Pei, Hua; Huang, Guangming; Xu, Nu; Gao, Chaosong; Xiao, Le

    2017-03-01

    We report the design and test results of a beam monitor developed for online monitoring in hadron therapy. The beam monitor uses eight silicon pixel sensors, Topmetal-II-, as the anode array. Topmetal-II- is a charge sensor designed in a CMOS 0.35 μm technology. Each Topmetal-II- sensor has 72×72 pixels and the pixel size is 83×83 μm2. In our design, the beam passes through the beam monitor without hitting the electrodes, making the beam monitor especially suitable for monitoring heavy ion beams. This design also reduces radiation damage to the beam monitor itself. The beam monitor is tested with a carbon ion beam at the Heavy Ion Research Facility in Lanzhou (HIRFL). Results indicate that the beam monitor can measure position, incidence angle and intensity of the beam with a position resolution better than 20 μm, angular resolution about 0.5° and intensity statistical accuracy better than 2%.

  10. Energy-correction photon counting pixel for photon energy extraction under pulse pile-up

    Science.gov (United States)

    Lee, Daehee; Park, Kyungjin; Lim, Kyung Taek; Cho, Gyuseong

    2017-06-01

    A photon counting detector (PCD) has been proposed as an alternative solution to an energy-integrating detector (EID) in medical imaging field due to its high resolution, high efficiency, and low noise. The PCD has expanded to variety of fields such as spectral CT, k-edge imaging, and material decomposition owing to its capability to count and measure the number and the energy of an incident photon, respectively. Nonetheless, pulse pile-up, which is a superimposition of pulses at the output of a charge sensitive amplifier (CSA) in each PC pixel, occurs frequently as the X-ray flux increases due to the finite pulse processing time (PPT) in CSAs. Pulse pile-up induces not only a count loss but also distortion in the measured X-ray spectrum from each PC pixel and thus it is a main constraint on the use of PCDs in high flux X-ray applications. To minimize these effects, an energy-correction PC (ECPC) pixel is proposed to resolve pulse pile-up without cutting off the PPT by adding an energy correction logic (ECL) via a cross detection method (CDM). The ECPC pixel with a size of 200×200 μm2 was fabricated by using a 6-metal 1-poly 0.18 μm CMOS process with a static power consumption of 7.2 μW/pixel. The maximum count rate of the ECPC pixel was extended by approximately three times higher than that of a conventional PC pixel with a PPT of 500 nsec. The X-ray spectrum of 90 kVp, filtered by 3 mm Al filter, was measured as the X-ray current was increased using the CdTe and the ECPC pixel. As a result, the ECPC pixel dramatically reduced the energy spectrum distortion at 2 Mphotons/pixel/s when compared to that of the ERCP pixel with the same 500 nsec PPT.

  11. Operational Experience with the ATLAS Pixel Detector

    CERN Document Server

    Lantzsch, Kerstin; The ATLAS collaboration

    2016-01-01

    Run 2 of the LHC is providing new challenges to track and vertex reconstruction with higher energies, denser jets and higher rates. Therefore the ATLAS experiment has constructed the first 4-layer Pixel detector in HEP, installing a new Pixel layer, also called Insertable B-Layer (IBL). In addition the Pixel detector was refurbished with new service quarter panels to recover about 3% of defective modules lost during run 1 and a new optical readout system to readout the data at higher speed while reducing the occupancy when running with increased luminosity. The commissioning, operation and performance of the 4-layer Pixel Detector will be presented.

  12. SOI pixel circuits with synchronized TMC for time-of-flight stigmatic imaging mass spectrometry

    CERN Document Server

    Watanabe, Kaori; Fujita, Youichi; Arai, Yasuo; Hazama, Hisanao

    2015-01-01

    We propose SOI pixel circuits with a synchronized time memory cell (TMC) for time-of-flight stigmatic imaging mass spectrometry. The circuits simultaneously detect the position and the fine/coarse flight time of an ion for the MALDI-ToF mass spectrometer. We discuss the circuit design and present the simulation results of a prototype detector comprised of a 32 x 32 pixel array in which each pixel pitch is 40 um and the time resolution is a minimum of 1 ns. The results of transient analysis demonstrate the fully correct synchronous operation at a 100-MHz clock frequency and simultaneous 32-word SRAM writing.

  13. Pixel-by-pixel VIS/NIR and LIR sensor fusion system

    Science.gov (United States)

    Zhang, Evan; Zhang, James S.; Song, Vivian W.; Chin, Ken P.; Hu, Gelbert

    2003-01-01

    Visible (VIS) camera (such as CCD) or Near Infrared (NIR) camera (such as low light level CCD or image intensifier) has high resolution and is easy to distinguish enemy and foe, but it cannot see through thin fog/cloud, heavy smoke/dust, foliage, camouflage, and darkness. The Long Infrared (LIR) imager can overcome above problems, but the resolution is too low and it cannot see the NIR aiming light from enemy. The best solution is to fuse the VIS/NIR and LIR sensors to overcome their shortcomings and take advantages of both sensors. In order to see the same target without parallax, the fusio system must have a common optical aperature. In this paper, three common optical apertures are designed: common reflective objective lens, common beam splitter, and common transmissive objective lens. The first one has very small field of view and the second one needs two heads, so the best choice is the third one, but we must find suitable optical materials and correct the color aberrations from 0.6 to 12 μ. It is a tough job. By choosing ZnSe as the first common piece of the objective lens and using glass for NIR and Ge (or IR glass) for LIR as rest pieces, we only need to and are able to correct the aberrations from 0.6 to 1.0 μ for NIR and from 8 to 12 μ for LIR. Finally, a common reflective objective lens and the common beam splitter are also successfully designed. Five application examples are given. In the digital signal processing, we use only one Altera chip. After inserting data, scaling the image size, and adjusting the signal level, the LIR will have the same format and same pixel number of the VIS/NIR, so real-time pixel-by-pixel sensor fusion is realized. The digital output can be used for further image processing and automatic target recognition, such as if we overlap the LIR image on the VIS/NIR image for missile guidance or rifle sight we don't need to worry about the time and the environment again. A gum-size wireless transmitter is also designed that is

  14. Implementation of TDI based digital pixel ROIC with 15μm pixel pitch

    Science.gov (United States)

    Ceylan, Omer; Shafique, Atia; Burak, A.; Caliskan, Can; Abbasi, Shahbaz; Yazici, Melik; Gurbuz, Yasar

    2016-05-01

    A 15um pixel pitch digital pixel for LWIR time delay integration (TDI) applications is implemented which occupies one fourth of pixel area compared to previous digital TDI implementation. TDI is implemented on 8 pixels with oversampling rate of 2. ROIC provides 16 bits output with 8 bits of MSB and 8 bits of LSB. Pixel can store 75 M electrons with a quantization noise of 500 electrons. Digital pixel TDI implementation is advantageous over analog counterparts considering power consumption, chip area and signal-to-noise ratio. Digital pixel TDI ROIC is fabricated with 0.18um CMOS process. In digital pixel TDI implementation photocurrent is integrated on a capacitor in pixel and converted to digital data in pixel. This digital data triggers the summation counters which implements TDI addition. After all pixels in a row contribute, the summed data is divided to the number of TDI pixels(N) to have the actual output which is square root of N improved version of a single pixel output in terms of signal-to-noise-ratio (SNR).

  15. Recent development of ultra small pixel uncooled focal plane arrays at DRS

    Science.gov (United States)

    Li, Chuan; Skidmore, George D.; Howard, Christopher; Han, C. J.; Wood, Lewis; Peysha, Doug; Williams, Eric; Trujillo, Carlos; Emmett, Jeff; Robas, Gary; Jardine, Daniel; Wan, C.-F.; Clarke, Elwood

    2007-04-01

    DRS is a major supplier of the 25μm pixel pitch 640x480 and 320x240 infrared uncooled focal plane arrays (UFPAs) and camera products for commercial and military markets. The state-of-the-art 25μm pixel focal plane arrays currently in production provide excellent performance for soldier thermal weapon sights (TWS), vehicle driver vision enhancers (DVE), and aerial surveillance and industrial thermograph applications. To further improve sensor resolution and reduce the sensor system size, weight and cost, it is highly desired to reduce the UFPA pixel size. However, the 17μm pixel FPA presents significant design and fabrication challenges as compared with 25μm pixel FPAs. The design objectives, engineering trade-offs, and performance goals will be discussed. This paper presents an overview of the 17μm microblometer uncooled focal plane arrays and sensor electronics production and development activities at DRS. The 17 μm pixel performance data from several initial fabrication lots will be summarized. Relevant 25μm pixel performance data are provided for comparison. Thermal images and video from the 17μm pixel 640x480 UFPA will also be presented.

  16. SNR improvement for hyperspectral application using frame and pixel binning

    Science.gov (United States)

    Rehman, Sami Ur; Kumar, Ankush; Banerjee, Arup

    2016-05-01

    Hyperspectral imaging spectrometer systems are increasingly being used in the field of remote sensing for variety of civilian and military applications. The ability of such instruments in discriminating finer spectral features along with improved spatial and radiometric performance have made such instruments a powerful tool in the field of remote sensing. Design and development of spaceborne hyper spectral imaging spectrometers poses lot of technological challenges in terms of optics, dispersion element, detectors, electronics and mechanical systems. The main factors that define the type of detectors are the spectral region, SNR, dynamic range, pixel size, number of pixels, frame rate, operating temperature etc. Detectors with higher quantum efficiency and higher well depth are the preferred choice for such applications. CCD based Si detectors serves the requirement of high well depth for VNIR band spectrometers but suffers from smear. Smear can be controlled by using CMOS detectors. Si CMOS detectors with large format arrays are available. These detectors generally have smaller pitch and low well depth. Binning technique can be used with available CMOS detectors to meet the large swath, higher resolution and high SNR requirements. Availability of larger dwell time of satellite can be used to bin multiple frames to increase the signal collection even with lesser well depth detectors and ultimately increase the SNR. Lab measurements reveal that SNR improvement by frame binning is more in comparison to pixel binning. Effect of pixel binning as compared to the frame binning will be discussed and degradation of SNR as compared to theoretical value for pixel binning will be analyzed.

  17. Automation of Endmember Pixel Selection in SEBAL/METRIC Model

    Science.gov (United States)

    Bhattarai, N.; Quackenbush, L. J.; Im, J.; Shaw, S. B.

    2015-12-01

    The commonly applied surface energy balance for land (SEBAL) and its variant, mapping evapotranspiration (ET) at high resolution with internalized calibration (METRIC) models require manual selection of endmember (i.e. hot and cold) pixels to calibrate sensible heat flux. Current approaches for automating this process are based on statistical methods and do not appear to be robust under varying climate conditions and seasons. In this paper, we introduce a new approach based on simple machine learning tools and search algorithms that provides an automatic and time efficient way of identifying endmember pixels for use in these models. The fully automated models were applied on over 100 cloud-free Landsat images with each image covering several eddy covariance flux sites in Florida and Oklahoma. Observed land surface temperatures at automatically identified hot and cold pixels were within 0.5% of those from pixels manually identified by an experienced operator (coefficient of determination, R2, ≥ 0.92, Nash-Sutcliffe efficiency, NSE, ≥ 0.92, and root mean squared error, RMSE, ≤ 1.67 K). Daily ET estimates derived from the automated SEBAL and METRIC models were in good agreement with their manual counterparts (e.g., NSE ≥ 0.91 and RMSE ≤ 0.35 mm day-1). Automated and manual pixel selection resulted in similar estimates of observed ET across all sites. The proposed approach should reduce time demands for applying SEBAL/METRIC models and allow for their more widespread and frequent use. This automation can also reduce potential bias that could be introduced by an inexperienced operator and extend the domain of the models to new users.

  18. Fully depleted CMOS pixel sensor development and potential applications

    Energy Technology Data Exchange (ETDEWEB)

    Baudot, J.; Kachel, M. [Universite de Strasbourg, IPHC, 23 rue du Loess 67037 Strasbourg (France); CNRS, UMR7178, 67037 Strasbourg (France)

    2015-07-01

    low noise figure. Especially, an energy resolution of about 400 eV for 5 keV X-rays was obtained for single pixels. The prototypes have then been exposed to gradually increased fluences of neutrons, from 10{sup 13} to 5x10{sup 14} neq/cm{sup 2}. Again laboratory tests allowed to evaluate the signal over noise persistence on the different pixels implemented. Currently our development mostly targets the detection of soft X-rays, with the ambition to develop a pixel sensor matching counting rates as affordable with hybrid pixel sensors, but with an extended sensitivity to low energy and finer pixel about 25 x 25 μm{sup 2}. The original readout architecture proposed relies on a two tiers chip. The first tier consists of a sensor with a modest dynamic in order to insure low noise performances required by sensitivity. The interconnected second tier chip enhances the read-out speed by introducing massive parallelization. Performances reachable with this strategy combining counting and integration will be detailed. (authors)

  19. Tracking performance of a single-crystal and a polycrystalline diamond pixel-detector

    Energy Technology Data Exchange (ETDEWEB)

    Menasce, D.; et al.

    2013-06-01

    We present a comparative characterization of the performance of a single-crystal and a polycrystalline diamond pixel-detector employing the standard CMS pixel readout chips. Measurements were carried out at the Fermilab Test Beam Facility, FTBF, using protons of momentum 120 GeV/c tracked by a high-resolution pixel telescope. Particular attention was directed to the study of the charge-collection, the charge-sharing among adjacent pixels and the achievable position resolution. The performance of the single-crystal detector was excellent and comparable to the best available silicon pixel-detectors. The measured average detection-efficiency was near unity, ε = 0.99860±0.00006, and the position-resolution for shared hits was about 6 μm. On the other hand, the performance of the polycrystalline detector was hampered by its lower charge collection distance and the readout chip threshold. A new readout chip, capable of operating at much lower threshold (around 1 ke$-$), would be required to fully exploit the potential performance of the polycrystalline diamond pixel-detector.

  20. Characterisation of pixel sensor prototypes for the ALICE ITS upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Reidt, Felix [CERN (Switzerland); Physikalisches Institut, Universitaet Heidelberg (Germany); Collaboration: ALICE-Collaboration

    2014-07-01

    ALICE is preparing a major upgrade of its experimental apparatus to be installed in the second long LHC shutdown (LS2) in the years 2018-2019. A key element of the upgrade is the replacement of the Inner Tracking System (ITS) deploying Monolithic Active Pixel Sensors (MAPS). The upgraded ITS will have a reduced material budget while increasing the pixel density and readout rate capabilities. The novel design leads to higher pointing and momentum resolution as well as a p{sub T} acceptance extended to lower values. The corresponding sensor prototypes were qualified in laboratory measurements and beam tests with respect to their radiation tolerance and detection efficiency. This talk summarises recent results on the characterisation of prototypes belonging to the ALPIDE family.

  1. Capacitively coupled hybrid pixel assemblies for the CLIC vertex detector

    CERN Document Server

    AUTHOR|(SzGeCERN)734627; Benoit, Mathieu; Dannheim, Dominik; Dette, Karola; Hynds, Daniel; Kulis, Szymon; Peric, Ivan; Petric, Marko; Redford, Sophie; Sicking, Eva; Valerio, Pierpaolo

    2016-01-01

    The vertex detector at the proposed CLIC multi-TeV linear e+e- collider must have minimal material content and high spatial resolution, combined with accurate time-stamping to cope with the expected high rate of beam-induced backgrounds. One of the options being considered is the use of active sensors implemented in a commercial high-voltage CMOS process, capacitively coupled to hybrid pixel ASICs. A prototype of such an assembly, using two custom designed chips (CCPDv3 as active sensor glued to a CLICpix readout chip), has been characterised both in the lab and in beam tests at the CERN SPS using 120 GeV/c positively charged hadrons. Results of these characterisation studies are presented both for single and dual amplification stages in the active sensor. Pixel cross-coupling results are also presented, showing the sensitivity to placement precision and planarity of the glue layer.

  2. 3D silicon pixel sensors: Recent test beam results

    CERN Document Server

    Hansson, P; Sandaker, H; Korolkov, I; Barrera, C; Wermes, N; Borri, M; Grinstein, S; Troyano, I; Grenier, P; Devetak, E; Fleta, C; Kenney, C; Tsybychev, D; Nellist, C; Chmeissan, M; Su, D; DeWilde, B; Silverstein, D; Dorholt, O; Tsung, J; Sjoebaek, K; Stupak, J; Slaviec, T; Micelli, A; Helle, K; Bolle, E; Huegging, F; Kocian, M; Fazio, S; Balbuena, J; Dalla Betta, G F; La Rosa, A; Rivero, F; Mastroberardino, A; Hasi, J; Darbo, G; Boscardin, M; Da Via, C; Nordahl, P; Giordani, M; Jackson, P; Rohne, O; Gemme, C; Young, C

    2011-01-01

    The 3D silicon sensors aimed for the ATLAS pixel detector upgrade have been tested with a high energy pion beam at the CERN SPS in 2009. Two types of sensor layouts were tested: full-3D assemblies fabricated in Stanford, where the electrodes penetrate the entire silicon wafer thickness, and modified-3D assemblies fabricated at FBK-irst with partially overlapping electrodes. In both cases three read-out electrodes are ganged together to form pixels of dimension 50 x 400 mu m(2). Data on the pulse height distribution, tracking efficiency and resolution were collected for various particle incident angles, with and without a 1.6 T magnetic field. Data from a planar sensor of the type presently used in the ATLAS detector were used at the same time to give comparison. Published by Elsevier B.V.

  3. 3D silicon pixel sensors: Recent test beam results

    Energy Technology Data Exchange (ETDEWEB)

    Hansson, P., E-mail: phansson@cern.c [University of Oslo (Norway); Balbuena, J.; Barrera, C. [CNM Barcelona (Spain); Bolle, E. [University of Oslo (Norway); Borri, M. [Torino University (Italy); Boscardin, M. [FBK Trento (Italy); Chmeissan, M. [IFAE Barcelona (Spain); Dalla Betta, G.-F. [Universita di Trento and INFN Trento (Italy); Darbo, G. [INFN Genova (Italy); Da Via, C. [University of Manchester (United Kingdom); Devetak, E.; DeWilde, B. [Stony Brook University (United States); Su, D. [SLAC (United States); Dorholt, O. [University of Oslo (Norway); Fazio, S. [Calabria University (Italy); Fleta, C. [CNM Barcelona (Spain); Gemme, C. [INFN Genova (Italy); Giordani, M. [University of Udine and INFN Udine (Italy); Gjersdal, H. [University of Oslo (Norway); Grenier, P. [SLAC (United States)

    2011-02-01

    The 3D silicon sensors aimed for the ATLAS pixel detector upgrade have been tested with a high energy pion beam at the CERN SPS in 2009. Two types of sensor layouts were tested: full-3D assemblies fabricated in Stanford, where the electrodes penetrate the entire silicon wafer thickness, and modified-3D assemblies fabricated at FBK-irst with partially overlapping electrodes. In both cases three read-out electrodes are ganged together to form pixels of dimension 50x400{mu}m{sup 2}. Data on the pulse height distribution, tracking efficiency and resolution were collected for various particle incident angles, with and without a 1.6 T magnetic field. Data from a planar sensor of the type presently used in the ATLAS detector were used at the same time to give comparison.

  4. Online Calibration and Performance of the ATLAS Pixel Detector

    CERN Document Server

    Keil, M

    2011-01-01

    The ATLAS Pixel Detector is the innermost detector of the ATLAS experiment at the Large Hadron Collider at CERN. It consists of 1744 silicon sensors equipped with approximately 80 million electronic channels, providing typically three measurement points with high resolution for particles emerging from the beam-interaction region, thus allowing measuring particle tracks and secondary vertices with very high precision. The readout system of the Pixel Detector is based on a bi-directional optical data transmission system between the detector and the data acquisition system with an individual link for each of the 1744 modules. Signal conversion components are located on both ends, approximately 80 m apart. This paper describes the tuning and calibration of the optical links and the detector modules, including measurements of threshold, noise, charge measurement, timing performance and the sensor leakage current.

  5. Compressive sensing spectroscopy with a single pixel camera.

    Science.gov (United States)

    Starling, David J; Storer, Ian; Howland, Gregory A

    2016-07-01

    Spectrometry requires high spectral resolution and high photometric precision while also balancing cost and complexity. We address these requirements by employing a compressive-sensing camera capable of improving signal acquisition speed and sensitivity in limited signal scenarios. In particular, we implement a fast single pixel spectrophotometer with no moving parts and measure absorption and emission spectra comparable with commercial products. Our method utilizes Hadamard matrices to sample the spectra and then minimizes the total variation of the signal. The experimental setup includes standard optics and a grating, a low-cost digital micromirror device, and an intensity detector. The resulting spectrometer produces a 512 pixel spectrum with low mean-squared error and up to a 90% reduction in data acquisition time when compared with a standard spectrophotometer.

  6. Signal variations in high granularity Si pixel detectors

    CERN Document Server

    Tlustos, L; Heijne, Erik H M; Llopart-Cudie, Xavier

    2004-01-01

    Fixed pattern noise is one of the limiting factors of image quality and degrades the achievable spatial resolution. In the case of silicon sensors non-uniformities due to doping inhomogeneities can be limited by operating the sensor in strong overdepletion. For high granularity photon counting pixel detectors an additional high frequency interpixel signal variation is an important factor for the achievable signal to noise ratio (SNR). It is common practice to apply flatfield corrections to increase the SNR of the detector system. For the case of direct conversion detectors it can be shown that the Poisson limit can be reached for floodfield irradiation. However when used for imaging with spectral X-ray sources flatfield corrections are less effective. This is partly a consequence of charge sharing between adjacent pixels, which gives rise to an effective energy spectrum seen by the readout, which is different from the spectral content of the incident beam. In this paper we present simulations and measurements...

  7. Pixel detector system development at Diamond Light Source

    Science.gov (United States)

    Marchal, J.; Horswell, I.; Gimenez, E. N.; Tartoni, N.

    2010-10-01

    Hybrid pixel detectors consisting of an array of silicon photodiodes bump-bonded to CMOS read-out chips provide high signal-to-noise ratio and high dynamic range compared to CCD-based detectors and Image Plates. These detector features are important for SAXS experiments where a wide range of intensities are present in the images. For time resolved SAXS experiments, high frame rates are compulsory. The latest CMOS read-out chip developed by the MEDIPIX collaboration provides high frame rate and continuous acquisition mode. A read-out system for an array of MEDIPIX3 sensors is under development at Diamond Light Source. This system will support a full resolution frame rate of 1 kHz at a pixel counter depth of 12-bit and a frame rate of 30 kHz at a counter depth of 1 bit. Details concerning system design and MEDIPIX sensors characterization are presented.

  8. GaAs Medipix2 hybrid pixel detector

    CERN Document Server

    Kostamo, P; Vähänen, S; Tlustos, L; Fröjdh, C; Campbell, M; Zhilyaev, Y; Lipsanen, H

    2008-01-01

    A GaAs Medipix2 hybrid pixel detector based on high purity epitaxial GaAs material was successfully fabricated. The mesa type GaAs sensor with 256×256 pixels and total area of 1.4×1.4 cm2 was made of a 140-μm-thick epitaxial p–i–n structure utilizing reactive ion etching. A final thickness of approximately 110 μm for the all-epitaxial sensor element is achieved by back-thinning procedure. The sensor element is bump bonded to a Medipix2 read-out ASIC. The detector is capable of room temperature spectroscopic operation and it demonstrates the potential of GaAs for high resolution X-ray imaging systems operating at room temperature. This work describes the manufacturing process and electrical properties of the GaAs Medipix2 hybrid detector.

  9. A 2D 4×4 Channel Readout ASIC for Pixelated CdTe Detectors for Medical Imaging Applications

    OpenAIRE

    Macias-Montero, Jose-Gabriel; Sarraj, Maher; Chmeissani, Mokhtar; Martínez, Ricardo; Puigdengoles, Carles

    2015-01-01

    We present a 16-channel readout integrated circuit (ROIC) with nanosecond-resolution time to digital converter (TDC) for pixelated Cadmium Telluride (CdTe) gamma-ray detectors. The 4 × 4 pixel array ROIC is the proof of concept of the 10 × 10 pixel array readout ASIC for positron-emission tomography (PET) scanner, positron-emission mammography (PEM) scanner, and Compton gamma camera. The electronics of each individual pixel integrates an analog front-end with switchable gain, an analog to dig...

  10. Study of the Tracking Method and Expected Performance of the Silicon Pixel Inner Tracker Applied in BESIII

    CERN Document Server

    Xiu, Qinglei; Li, Weidong; Liu, Huaimin; Ma, Qiumei; Ouyang, Qun; Qin, Zhonghua; Wang, Liangliang; Wu, Linghui; Yuan, Ye; Zhang, Yao

    2015-01-01

    The inner drift chamber of the BESIII is encountering serious aging problem after five year's running. For the first layer, the decrease in gas gain is about 26% from 2009 to 2013. The upgrade of the inner tracking detector has become an urgent problem for the BESIII experiment. An inner tracker using CMOS pixel sensors is an important candidate because of its great advantages on spatial resolution and radiation hardness. In order to carry out a Monte Carlo study on the expected performance, a Geant4-based full simulation for the silicon pixel detector has been implemented. The tracking method combining the silicon pixel inner tracker and outer drift chamber has been studied and a preliminary reconstruction software was developed. The Monte Carlo study shows that the performances including momentum resolution, vertex resolution and the tracking efficiency are significantly improved due to the good spatial resolution and moderate material budget of the silicon pixel detector.

  11. Comparison Between Linear and Nonlinear Models of Mixed Pixels in Remote Sensing Satellite Images Based on Cierniewski Surface BRDF Model by Means of Monte Carlo Ray Tracing Simulation

    Directory of Open Access Journals (Sweden)

    Kohei Arai

    2013-04-01

    Full Text Available Comparative study on linear and nonlinear mixed pixel models of which pixels in remote sensing satellite images is composed with plural ground cover materials mixed together, is conducted for remote sensing satellite image analysis. The mixed pixel models are based on Cierniewski of ground surface reflectance model. The comparative study is conducted by using of Monte Carlo Ray Tracing: MCRT simulations. Through simulation study, the difference between linear and nonlinear mixed pixel models is clarified. Also it is found that the simulation model is validated.

  12. Land Cover Heterogeneity Effects on Sub-Pixel and Per-Pixel Classifications

    Directory of Open Access Journals (Sweden)

    Trung V. Tran

    2014-04-01

    Full Text Available Per-pixel and sub-pixel are two common classification methods in land cover studies. The characteristics of a landscape, particularly the land cover itself, can affect the accuracies of both methods. The objectives of this study were to: (1 compare the performance of sub-pixel vs. per-pixel classification methods for a broad heterogeneous region; and (2 analyze the impact of land cover heterogeneity (i.e., the number of land cover classes per pixel on both classification methods. The results demonstrated that the accuracy of both per-pixel and sub-pixel classification methods were generally reduced by increasing land cover heterogeneity. Urban areas, for example, were found to have the lowest accuracy for the per-pixel method, because they had the highest heterogeneity. Conversely, rural areas dominated by cropland and grassland had low heterogeneity and high accuracy. When a sub-pixel method was used, the producer’s accuracy for artificial surfaces was increased by more than 20%. For all other land cover classes, sub-pixel and per-pixel classification methods performed similarly. Thus, the sub-pixel classification was only advantageous for heterogeneous urban landscapes. Both creators and users of land cover datasets should be aware of the inherent landscape heterogeneity and its potential effect on map accuracy.

  13. ISPA (imaging silicon pixel array) experiment

    CERN Multimedia

    Patrice Loïez

    2002-01-01

    The bump-bonded silicon pixel detector, developed at CERN by the EP-MIC group, is shown here in its ceramic carrier. Both represent the ISPA-tube anode. The chip features between 1024 (called OMEGA-1) and 8196 (ALICE-1) active pixels.

  14. A NEW OBJECT-BASED FRAMEWORK TO DETECT SHODOWS IN HIGH-RESOLUTION SATELLITE IMAGERY OVER URBAN AREAS

    Directory of Open Access Journals (Sweden)

    N. Tatar

    2015-12-01

    Full Text Available In this paper a new object-based framework to detect shadow areas in high resolution satellite images is proposed. To produce shadow map in pixel level state of the art supervised machine learning algorithms are employed. Automatic ground truth generation based on Otsu thresholding on shadow and non-shadow indices is used to train the classifiers. It is followed by segmenting the image scene and create image objects. To detect shadow objects, a majority voting on pixel-based shadow detection result is designed. GeoEye-1 multi-spectral image over an urban area in Qom city of Iran is used in the experiments. Results shows the superiority of our proposed method over traditional pixel-based, visually and quantitatively.

  15. Hexagonal Pixels and Indexing Scheme for Binary Images

    Science.gov (United States)

    Johnson, Gordon G.

    2004-01-01

    A scheme for resampling binaryimage data from a rectangular grid to a regular hexagonal grid and an associated tree-structured pixel-indexing scheme keyed to the level of resolution have been devised. This scheme could be utilized in conjunction with appropriate image-data-processing algorithms to enable automated retrieval and/or recognition of images. For some purposes, this scheme is superior to a prior scheme that relies on rectangular pixels: one example of such a purpose is recognition of fingerprints, which can be approximated more closely by use of line segments along hexagonal axes than by line segments along rectangular axes. This scheme could also be combined with algorithms for query-image-based retrieval of images via the Internet. A binary image on a rectangular grid is generated by raster scanning or by sampling on a stationary grid of rectangular pixels. In either case, each pixel (each cell in the rectangular grid) is denoted as either bright or dark, depending on whether the light level in the pixel is above or below a prescribed threshold. The binary data on such an image are stored in a matrix form that lends itself readily to searches of line segments aligned with either or both of the perpendicular coordinate axes. The first step in resampling onto a regular hexagonal grid is to make the resolution of the hexagonal grid fine enough to capture all the binaryimage detail from the rectangular grid. In practice, this amounts to choosing a hexagonal-cell width equal to or less than a third of the rectangular- cell width. Once the data have been resampled onto the hexagonal grid, the image can readily be checked for line segments aligned with the hexagonal coordinate axes, which typically lie at angles of 30deg, 90deg, and 150deg with respect to say, the horizontal rectangular coordinate axis. Optionally, one can then rotate the rectangular image by 90deg, then again sample onto the hexagonal grid and check for line segments at angles of 0deg, 60deg

  16. Imaging and spectroscopic performance studies of pixellated CdTe Timepix detector

    Science.gov (United States)

    Maneuski, D.; Astromskas, V.; Fröjdh, E.; Fröjdh, C.; Gimenez, E. N.; Marchal, J.; O'Shea, V.; Stewart, G.; Tartoni, N.; Wilhelm, H.; Wraight, K.; Zain, R. M.

    2012-01-01

    In this work the results on imaging and spectroscopic performances of 14 × 14 × 1 mm CdTe detectors with 55 × 55 μm and 110 × 110 μm pixel pitch bump-bonded to a Timepix chip are presented. The performance of the 110 × 110 μm pixel detector was evaluated at the extreme conditions beam line I15 of the Diamond Light Source. The energy of X-rays was set between 25 and 77 keV. The beam was collimated through the edge slits to 20 μm FWHM incident in the middle of the pixel. The detector was operated in the time-over-threshold mode, allowing direct energy measurement. Energy in the neighbouring pixels was summed for spectra reconstruction. Energy resolution at 77 keV was found to be ΔE/E = 3.9%. Comparative imaging and energy resolution studies were carried out between two pixel size detectors with a fluorescence target X-ray tube and radioactive sources. The 110 × 110 μm pixel detector exhibited systematically better energy resolution in comparison to 55 × 55 μm. An imaging performance of 55 × 55 μm pixellated CdTe detector was assessed using the Modulation Transfer Function (MTF) technique and compared to the larger pixel. A considerable degradation in MTF was observed for bias voltages below -300 V. Significant room for improvement of the detector performance was identified both for imaging and spectroscopy and is discussed.

  17. Estimation of Carbon Budgets for Croplands by Combining High Resolution Remote Sensing Data with a Crop Model and Validation Ground Data

    Science.gov (United States)

    Mangiarotti, S.; Veloso, A.; Ceschia, E.; Tallec, T.; Dejoux, J. F.

    2015-12-01

    Croplands occupy large areas of Earth's land surface playing a key role in the terrestrial carbon cycle. Hence, it is essential to quantify and analyze the carbon fluxes from those agro-ecosystems, since they contribute to climate change and are impacted by the environmental conditions. In this study we propose a regional modeling approach that combines high spatial and temporal resolutions (HSTR) optical remote sensing data with a crop model and a large set of in-situ measurements for model calibration and validation. The study area is located in southwest France and the model that we evaluate, called SAFY-CO2, is a semi-empirical one based on the Monteith's light-use efficiency theory and adapted for simulating the components of the net ecosystem CO2 fluxes (NEE) and of the annual net ecosystem carbon budgets (NECB) at a daily time step. The approach is based on the assimilation of satellite-derived green area index (GAI) maps for calibrating a number of the SAFY-CO2 parameters linked to crop phenology. HSTR data from the Formosat-2 and SPOT satellites were used to produce the GAI maps. The experimental data set includes eddy covariance measurements of net CO2 fluxes from two experimental sites and partitioned into gross primary production (GPP) and ecosystem respiration (Reco). It also includes measurements of GAI, biomass and yield between 2005 and 2011, focusing on the winter wheat crop. The results showed that the SAFY-CO2 model correctly reproduced the biomass production, its dynamic and the yield (relative errors about 24%) in contrasted climatic, environmental and management conditions. The net CO2 flux components estimated with the model were overall in agreement with the ground data, presenting good correlations (R² about 0.93 for GPP, 0.77 for Reco and 0.86 for NEE). The evaluation of the modelled NECB for the different site-years highlighted the importance of having accurate estimates of each component of the NECB. Future works aim at considering

  18. Comparison of Mixed Layer Heights from Airborne High Spectral Resolution Lidar, Ground-based Measurements, and the WRP-Chem Model during CalNex and CARES

    Energy Technology Data Exchange (ETDEWEB)

    Scarino, Amy Jo; Obland, Michael; Fast, Jerome D.; Burton, S. P.; Ferrare, R. A.; Hostetler, Chris A.; Berg, Larry K.; Lefer, Barry; Haman, C.; Hair, John; Rogers, Ray; Butler, Carolyn; Cook, A. L.; Harper, David

    2014-06-05

    The California Research at the Nexus of Air Quality and Climate Change (CalNex) and Carbonaceous Aerosol and Radiative Effects Study (CARES) field campaigns during May and June 2010 provided a data set appropriate for studying characteristics of the planetary boundary layer (PBL). The NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL) was deployed to California onboard the NASA LaRC B-200 aircraft to aid incharacterizing aerosol properties during these two field campaigns. Measurements of aerosol extinction (532 nm), backscatter (532 and 1064 nm), and depolarization (532 and 1064 nm) profiles during 31 flights, many in coordination with other research aircraft and ground sites, constitute a diverse data set for use in characterizing the spatial and temporal distribution of aerosols, as well as the depth and variability of the daytime mixed layer (ML), which is a subset within the PBL. This work illustrates the temporal and spatial variability of the ML in the vicinity of Los Angeles and Sacramento, CA. ML heights derived from HSRL measurements are compared to PBL heights derived from radiosonde profiles, ML heights measured from ceilometers, and simulated PBL heights from the Weather Research and Forecasting Chemistry (WRF-Chem) community model. Comparisons between the HSRL ML heights and the radiosonde profiles in Sacramento result in a correlation coefficient value (R) of 0.93 (root7 mean-square (RMS) difference of 157 m and bias difference (HSRL radiosonde) of 5 m). HSRL ML heights compare well with those from the ceilometer in the LA Basin with an R of 0.89 (RMS difference of 108 m and bias difference (HSRL Ceilometer) of -9.7 m) for distances of up to 30 km between the B-200 flight track and the ceilometer site. Simulated PBL heights from WRF-Chem were compared with those obtained from all flights for each campaign, producing an R of 0.58 (RMS difference of 604 m and a bias difference (WRF-Chem HSRL) of -157 m) for CalNex and 0

  19. Improved instrumental line shape monitoring for the ground-based, high-resolution FTIR spectrometers of the Network for the Detection of Atmospheric Composition Change

    Directory of Open Access Journals (Sweden)

    F. Hase

    2012-03-01

    Full Text Available We propose an improved monitoring scheme for the instrumental line shape (ILS of high-resolution, ground-based FTIR (Fourier Transform InfraRed spectrometers used for chemical monitoring of the atmosphere by the Network for Detection of Atmospheric Composition Change (NDACC. Good ILS knowledge is required for the analysis of the recorded mid-infrared spectra. The new method applies a sequence of measurements using different gas cells instead of a single calibration cell. Three cells are used: cell C1 is a refillable cell offering 200 mm path length and equipped with a pressure gauge (filled with 100 Pa N2O, cells C2 and C3 are sealed cells offering 75 mm path length. C2 is filled with 5 Pa of pure N2O. Cell C3 is filled with 16 Pa N2O in 200 hPa technical air, so provides pressure-broadened N2O lines. We demonstrate that an ILS retrieval using C1 improves significantly the sensitivity of the ILS retrieval over the current calibration cells used in the network, because this cell provides narrow fully saturated N2O lines. The N2O columns derived from C2 and C3 allow the performance of a highly valuable closure experiment: adopting the ILS retrieved from C1, the N2O columns of C2 and C3 are derived. Because N2O is an inert gas, both columns should be constant on long timescales. Apparent changes in the columns would immediately attract attention and indicate either inconsistent ILS results or instrumental problems of other origin. Two different cells are applied for the closure experiment, because the NDACC spectrometers observe both stratospheric and tropospheric gases: C2 mimics signatures of stratospheric gases, whereas C3 mimics signatures of tropospheric gases.

  20. Where can pixel counting area estimates meet user-defined accuracy requirements?

    Science.gov (United States)

    Waldner, François; Defourny, Pierre

    2017-08-01

    Pixel counting is probably the most popular way to estimate class areas from satellite-derived maps. It involves determining the number of pixels allocated to a specific thematic class and multiplying it by the pixel area. In the presence of asymmetric classification errors, the pixel counting estimator is biased. The overarching objective of this article is to define the applicability conditions of pixel counting so that the estimates are below a user-defined accuracy target. By reasoning in terms of landscape fragmentation and spatial resolution, the proposed framework decouples the resolution bias and the classifier bias from the overall classification bias. The consequence is that prior to any classification, part of the tolerated bias is already committed due to the choice of the spatial resolution of the imagery. How much classification bias is affordable depends on the joint interaction of spatial resolution and fragmentation. The method was implemented over South Africa for cropland mapping, demonstrating its operational applicability. Particular attention was paid to modeling a realistic sensor's spatial response by explicitly accounting for the effect of its point spread function. The diagnostic capabilities offered by this framework have multiple potential domains of application such as guiding users in their choice of imagery and providing guidelines for space agencies to elaborate the design specifications of future instruments.

  1. AN ADAPTIVE MORPHOLOGICAL MEAN FILTER FOR VERY HIGH-RESOLUTION REMOTE SENSING IMAGE PROCESSING

    Directory of Open Access Journals (Sweden)

    Z. Lv

    2017-09-01

    Full Text Available Very high resolution (VHR remote sensing imagery can reveal the ground object in greater detail, depicting their color, shape, size and structure. However, VHR also leads much original noise in spectra, and this original noise may reduce the reliability of the classification’s result. This paper presents an Adaptive Morphological Mean Filter (AMMF for smoothing the original noise of VHR imagery and improving the classification’s performance. AMMF is a shape-adaptive filter which is constructed by detecting gradually the spectral similarity between a kernel-anchored pixel and its contextual pixels through an extension-detector with 8-neighbouring pixels, and the spectral value of the kernel-anchored pixel is instead by the mean of group pixels within the adaptive region. The classification maps based on the AMMF are compared with the classification of VHR images based on the homologous filter processing, such as Mean Filter (MF and Median Filter(MedF. The experimental results suggest the following: 1 VHR image processed using AMMF can not only preserve the detail information among inter-classes but also smooth the noise within intra-class; 2 The proposed AMMF processing can improve the classification’s performance of VHR image, and it obtains a better visual performance and accuracy while comparing with MF and MedF.

  2. A Smart Pixel Camera for future Cherenkov Telescopes

    CERN Document Server

    Hermann, G; Glück, B; Hauser, D; Hermann, German; Carrigan, Svenja; Gl\\"uck, Bernhard; Hauser, Dominik

    2005-01-01

    The Smart Pixel Camera is a new camera for imaging atmospheric Cherenkov telescopes, suited for a next generation of large multi-telescope ground based gamma-ray observatories. The design of the camera foresees all electronics needed to process the images to be located inside the camera body at the focal plane. The camera has a modular design and is scalable in the number of pixels. The camera electronics provides the performance needed for the next generation instruments, like short signal integration time, topological trigger and short trigger gate, and at the same time the design is optimized to minimize the cost per channel. In addition new features are implemented, like the measurement of the arrival time of light pulses in the pixels on the few hundred psec timescale. The buffered readout system of the camera allows to take images at sustained rates of O(10 kHz) with a dead-time of only about 0.8 % per kHz.

  3. Joint Sparse Sub-Pixel Mapping Model with Endmember Variability for Remotely Sensed Imagery

    Directory of Open Access Journals (Sweden)

    Xiong Xu

    2016-12-01

    Full Text Available Spectral unmixing and sub-pixel mapping have been used to estimate the proportion and spatial distribution of the different land-cover classes in mixed pixels at a sub-pixel scale. In the past decades, several algorithms were proposed in both categories; however, these two techniques are generally regarded as independent procedures, with most sub-pixel mapping methods using abundance maps generated by spectral unmixing techniques. It should be noted that the utilized abundance map has a strong impact on the performance of the subsequent sub-pixel mapping process. Recently, we built a novel sub-pixel mapping model in combination with the linear spectral mixture model. Therefore, a joint sub-pixel mapping model was established that connects an original (coarser resolution remotely sensed image with the final sub-pixel result directly. However, this approach focuses on incorporating the spectral information contained in the original image without addressing the spectral endmember variability resulting from variable illumination and environmental conditions. To address this important issue, in this paper we designed a new joint sparse sub-pixel mapping method under the assumption that various representative spectra for each endmember are known a priori and available in a library. In addition, the total variation (TV regularization was also adopted to exploit the spatial information. The proposed approach was experimentally evaluated using both synthetic and real hyperspectral images, and the obtained results demonstrate that the method can achieve better results by considering the impact of endmember variability when compared with other sub-pixel mapping methods.

  4. Urban Image Classification: Per-Pixel Classifiers, Sub-Pixel Analysis, Object-Based Image Analysis, and Geospatial Methods. 10; Chapter

    Science.gov (United States)

    Myint, Soe W.; Mesev, Victor; Quattrochi, Dale; Wentz, Elizabeth A.

    2013-01-01

    Remote sensing methods used to generate base maps to analyze the urban environment rely predominantly on digital sensor data from space-borne platforms. This is due in part from new sources of high spatial resolution data covering the globe, a variety of multispectral and multitemporal sources, sophisticated statistical and geospatial methods, and compatibility with GIS data sources and methods. The goal of this chapter is to review the four groups of classification methods for digital sensor data from space-borne platforms; per-pixel, sub-pixel, object-based (spatial-based), and geospatial methods. Per-pixel methods are widely used methods that classify pixels into distinct categories based solely on the spectral and ancillary information within that pixel. They are used for simple calculations of environmental indices (e.g., NDVI) to sophisticated expert systems to assign urban land covers. Researchers recognize however, that even with the smallest pixel size the spectral information within a pixel is really a combination of multiple urban surfaces. Sub-pixel classification methods therefore aim to statistically quantify the mixture of surfaces to improve overall classification accuracy. While within pixel variations exist, there is also significant evidence that groups of nearby pixels have similar spectral information and therefore belong to the same classification category. Object-oriented methods have emerged that group pixels prior to classification based on spectral similarity and spatial proximity. Classification accuracy using object-based methods show significant success and promise for numerous urban 3 applications. Like the object-oriented methods that recognize the importance of spatial proximity, geospatial methods for urban mapping also utilize neighboring pixels in the classification process. The primary difference though is that geostatistical methods (e.g., spatial autocorrelation methods) are utilized during both the pre- and post

  5. Measurement of ground displacement from optical satellite image correlation using the free open-source software MicMac

    Science.gov (United States)

    Rosu, Ana-Maria; Pierrot-Deseilligny, Marc; Delorme, Arthur; Binet, Renaud; Klinger, Yann

    2015-02-01

    Image correlation is one of the most efficient techniques to determine horizontal ground displacements due to earthquakes, landslides, ice flows or sand dune migrations. Analyzing these deformations allows a better understanding of the causes and mechanisms of the events. By using sub-pixel correlation on before- and after-event ortho-images obtained from high resolution satellite images it is possible to compute the displacement field with high planimetric resolution. In this paper, we focus on measuring the ground displacements due to seismotectonic events. The three sub-pixel correlators used are: COSI-Corr - developed by Caltech, a free, closed-source correlator, dependent on commercial software (ENVI) and widely used by the geoscience community for measuring ground displacement; Medicis - developed by CNES, also a closed-source correlator capable of measuring this type of deformation; and MicMac - developed by IGN, the free open-source correlator we study and tune for measuring fine ground displacements. We measured horizontal ground deformation using these three correlators on SPOT images in three study cases: the 2001 Kokoxili earthquake, the 2005 dyke intrusion in the Afar depression and the 2008 Yutian earthquake.

  6. Toward VIP-PIX: A Low Noise Readout ASIC for Pixelated CdTe Gamma-Ray Detectors for Use in the Next Generation of PET Scanners

    OpenAIRE

    Macias-Montero, Jose-Gabriel; Sarraj, Maher; Chmeissani, Mokhtar; Puigdengoles, Carles; Lorenzo, Gianluca De; Martínez, Ricardo

    2013-01-01

    VIP-PIX will be a low noise and low power pixel readout electronics with digital output for pixelated Cadmium Telluride (CdTe) detectors. The proposed pixel will be part of a 2D pixel-array detector for various types of nuclear medicine imaging devices such as positron-emission tomography (PET) scanners, Compton gamma cameras, and positron-emission mammography (PEM) scanners. Each pixel will include a SAR ADC that provides the energy deposited with 10-bit resolution. Simultaneously, the self-...

  7. It's not the pixel count, you fool

    Science.gov (United States)

    Kriss, Michael A.

    2012-01-01

    The first thing a "marketing guy" asks the digital camera engineer is "how many pixels does it have, for we need as many mega pixels as possible since the other guys are killing us with their "umpteen" mega pixel pocket sized digital cameras. And so it goes until the pixels get smaller and smaller in order to inflate the pixel count in the never-ending pixel-wars. These small pixels just are not very good. The truth of the matter is that the most important feature of digital cameras in the last five years is the automatic motion control to stabilize the image on the sensor along with some very sophisticated image processing. All the rest has been hype and some "cool" design. What is the future for digital imaging and what will drive growth of camera sales (not counting the cell phone cameras which totally dominate the market in terms of camera sales) and more importantly after sales profits? Well sit in on the Dark Side of Color and find out what is being done to increase the after sales profits and don't be surprised if has been done long ago in some basement lab of a photographic company and of course, before its time.

  8. Upgrades of the ATLAS Pixel Detector

    CERN Document Server

    Hügging, F; The ATLAS collaboration

    2013-01-01

    The upgrade for the ATLAS detector will undergo different phases towards HL-LHC. The first upgrade for the Pixel Detector (Phase 1) consists in the construction of a new pixel layer, which will be installed during the 1st long shutdown of the LHC machine (LS1) in 2013/14. The new detector, called Insertable B-Layer (IBL), will be inserted between the existing pixel detector and a new (smaller radius) beam-pipe at a radius of about 3.2 cm. The IBL requires the development of several new technologies to cope with the increase of radiation and pixel occupancy as well as to improve the physics performance of the existing pixel detector. The pixel size is reduced and the material budget is minimized by using new lightweight mechanical support materials and a CO2 based cooling system. For Phase 2 upgrade of LHC a complete new 4-layer pixel system is planned as part of a new all silicon Inner Detector. The increase in luminosity to about $5\\cdot 10^{34}$cm$^{-2}$s$^{-1}$ together with a total expected lifetime of ab...

  9. Detection of sub-pixel fractures in X-ray dark-field tomography

    Energy Technology Data Exchange (ETDEWEB)

    Lauridsen, Torsten; Feidenhans' l, Robert [University of Copenhagen, Niels Bohr Institute, Copenhagen (Denmark); Willner, Marian; Pfeiffer, Franz [Technische Universitaet Muenchen, Department of Physics and Institute of Medical Engineering, Garching (Germany); Bech, Martin [Lund University, Medical Radiation Physics, Lund (Sweden)

    2015-11-15

    We present a new method for detecting fractures in solid materials below the resolution given by the detector pixel size by using grating-based X-ray interferometry. The technique is particularly useful for detecting sub-pixel cracks in large samples where the size of the sample is preventing high-resolution μCT studies of the entire sample. The X-ray grating interferometer produces three distinct modality signals: absorption, phase and dark field. The method utilizes the unique scattering features of the dark-field signal. We have used tomograms reconstructed from each of the three signals to detect cracks in a model sample consisting of stearin. (orig.)

  10. Evaluation of 65nm technology for CLIC pixel front-end

    CERN Document Server

    Valerio, P; Ballabriga, R; Campbell, M; Llopart, X

    2011-01-01

    The CLIC vertex detector design requires a high single point resolution (~ 3 μm) and a precise time stamp (≤ 10 ns). In order to achieve this spatial resolution, small pixels (in the order of 20 μm pitch) must be used, together with the measurement of the charge deposition of neighbouring channels. Designing such small pixels requires the use of a deep downscaled CMOS technology. This note describes the design and characterisation of suitable building blocks implemented in a commercial 65 nm process. The characterisation included an evaluation of the radiation hardness of the blocks.

  11. Optimization of the performance of a pixellated germanium Compton camera

    OpenAIRE

    Ghoggali, W.

    2015-01-01

    A planar HPGe Compton camera for nuclear medicine applications that contains 177 pixels of 4 × 4mm2, of which 25 are at the back detector, is being used to image point sources of Cs137, line sources and clinical-like shape distributed sources. Experimental results are obtained to study the e ffects of energy resolution, position sensitivity, and reconstruction algorithms on camera images. Preamplifi ed pulses are digitized for pulse shape analysis using gamma ray tracking GRT4s data acquisiti...

  12. Hyperspectral imaging using the single-pixel Fourier transform technique

    Science.gov (United States)

    Jin, Senlin; Hui, Wangwei; Wang, Yunlong; Huang, Kaicheng; Shi, Qiushuai; Ying, Cuifeng; Liu, Dongqi; Ye, Qing; Zhou, Wenyuan; Tian, Jianguo

    2017-03-01

    Hyperspectral imaging technology is playing an increasingly important role in the fields of food analysis, medicine and biotechnology. To improve the speed of operation and increase the light throughput in a compact equipment structure, a Fourier transform hyperspectral imaging system based on a single-pixel technique is proposed in this study. Compared with current imaging spectrometry approaches, the proposed system has a wider spectral range (400-1100 nm), a better spectral resolution (1 nm) and requires fewer measurement data (a sample rate of 6.25%). The performance of this system was verified by its application to the non-destructive testing of potatoes.

  13. X-ray Characterization of a Multichannel Smart-Pixel Array Detector

    Energy Technology Data Exchange (ETDEWEB)

    Ross, Steve; Haji-Sheikh, Michael; Huntington, Andrew; Kline, David; Lee, Adam; Li, Yuelin; Rhee, Jehyuk; Tarpley, Mary; Walko, Donald A.; Westberg, Gregg; Williams, George; Zou, Haifeng; Landahl, Eric

    2016-01-01

    The Voxtel VX-798 is a prototype X-ray pixel array detector (PAD) featuring a silicon sensor photodiode array of 48 x 48 pixels, each 130 mu m x 130 mu m x 520 mu m thick, coupled to a CMOS readout application specific integrated circuit (ASIC). The first synchrotron X-ray characterization of this detector is presented, and its ability to selectively count individual X-rays within two independent arrival time windows, a programmable energy range, and localized to a single pixel is demonstrated. During our first trial run at Argonne National Laboratory's Advance Photon Source, the detector achieved a 60 ns gating time and 700 eV full width at half-maximum energy resolution in agreement with design parameters. Each pixel of the PAD holds two independent digital counters, and the discriminator for X-ray energy features both an upper and lower threshold to window the energy of interest discarding unwanted background. This smart-pixel technology allows energy and time resolution to be set and optimized in software. It is found that the detector linearity follows an isolated dead-time model, implying that megahertz count rates should be possible in each pixel. Measurement of the line and point spread functions showed negligible spatial blurring. When combined with the timing structure of the synchrotron storage ring, it is demonstrated that the area detector can perform both picosecond time-resolved X-ray diffraction and fluorescence spectroscopy measurements.

  14. Fast Imaging Detector Readout Circuits with In-Pixel ADCs for Fourier Transform Imaging Spectrometers

    Science.gov (United States)

    Rider, D.; Blavier, J-F.; Cunningham, T.; Hancock, B.; Key, R.; Pannell, Z.; Sander, S.; Seshadri, S.; Sun, C.; Wrigley, C.

    2011-01-01

    Focal plane arrays (FPAs) with high frame rates and many pixels benefit several upcoming Earth science missions including GEO-CAPE, GACM, and ACE by enabling broader spatial coverage and higher spectral resolution. FPAs for the PanFTS, a high spatial resolution Fourier transform spectrometer and a candidate instrument for the GEO-CAPE mission are the focus of the developments reported here, but this FPA technology has the potential to enable a variety of future measurements and instruments. The ESTO ACT Program funded the developed of a fast readout integrated circuit (ROIC) based on an innovative in-pixel analog-to-digital converter (ADC). The 128 X 128 pixel ROIC features 60 ?m pixels, a 14-bit ADC in each pixel and operates at a continuous frame rate of 14 kHz consuming only 1.1 W of power. The ROIC outputs digitized data completely eliminating the bulky, power consuming signal chains needed by conventional FPAs. The 128 X 128 pixel ROIC has been fabricated in CMOS and tested at the Jet Propulsion Laboratory. The current version is designed to be hybridized with PIN photodiode arrays via indium bump bonding for light detection in the visible and ultraviolet spectral regions. However, the ROIC design incorporates a small photodiode in each cell to permit detailed characterization of the ROICperformance without the need for hybridization. We will describe the essential features of the ROIC design and present results of ROIC performance measurements.

  15. Fast Imaging Detector Readout Circuits with In-Pixel ADCs for Fourier Transform Imaging Spectrometers

    Science.gov (United States)

    Rider, D.; Blavier, J-F.; Cunningham, T.; Hancock, B.; Key, R.; Pannell, Z.; Sander, S.; Seshadri, S.; Sun, C.; Wrigley, C.

    2011-01-01

    Focal plane arrays (FPAs) with high frame rates and many pixels benefit several upcoming Earth science missions including GEO-CAPE, GACM, and ACE by enabling broader spatial coverage and higher spectral resolution. FPAs for the PanFTS, a high spatial resolution Fourier transform spectrometer and a candidate instrument for the GEO-CAPE mission are the focus of the developments reported here, but this FPA technology has the potential to enable a variety of future measurements and instruments. The ESTO ACT Program funded the developed of a fast readout integrated circuit (ROIC) based on an innovative in-pixel analog-to-digital converter (ADC). The 128 X 128 pixel ROIC features 60 ?m pixels, a 14-bit ADC in each pixel and operates at a continuous frame rate of 14 kHz consuming only 1.1 W of power. The ROIC outputs digitized data completely eliminating the bulky, power consuming signal chains needed by conventional FPAs. The 128 X 128 pixel ROIC has been fabricated in CMOS and tested at the Jet Propulsion Laboratory. The current version is designed to be hybridized with PIN photodiode arrays via indium bump bonding for light detection in the visible and ultraviolet spectral regions. However, the ROIC design incorporates a small photodiode in each cell to permit detailed characterization of the ROICperformance without the need for hybridization. We will describe the essential features of the ROIC design and present results of ROIC performance measurements.

  16. Development of a mixed pixel filter for improved dimension estimation using AMCW laser scanner

    Science.gov (United States)

    Wang, Qian; Sohn, Hoon; Cheng, Jack C. P.

    2016-09-01

    Accurate dimension estimation is desired in many fields, but the traditional dimension estimation methods are time-consuming and labor-intensive. In the recent decades, 3D laser scanners have become popular for dimension estimation due to their high measurement speed and accuracy. Nonetheless, scan data obtained by amplitude-modulated continuous-wave (AMCW) laser scanners suffer from erroneous data called mixed pixels, which can influence the accuracy of dimension estimation. This study develops a mixed pixel filter for improved dimension estimation using AMCW laser scanners. The distance measurement of mixed pixels is firstly formulated based on the working principle of laser scanners. Then, a mixed pixel filter that can minimize the classification errors between valid points and mixed pixels is developed. Validation experiments were conducted to verify the formulation of the distance measurement of mixed pixels and to examine the performance of the proposed mixed pixel filter. Experimental results show that, for a specimen with dimensions of 840 mm × 300 mm, the overall errors of the dimensions estimated after applying the proposed filter are 1.9 mm and 1.0 mm for two different scanning resolutions, respectively. These errors are much smaller than the errors (4.8 mm and 3.5 mm) obtained by the scanner's built-in filter.

  17. Design, optimization and evaluation of a "smart" pixel sensor array for low-dose digital radiography

    Science.gov (United States)

    Wang, Kai; Liu, Xinghui; Ou, Hai; Chen, Jun

    2016-04-01

    Amorphous silicon (a-Si:H) thin-film transistors (TFTs) have been widely used to build flat-panel X-ray detectors for digital radiography (DR). As the demand for low-dose X-ray imaging grows, a detector with high signal-to-noise-ratio (SNR) pixel architecture emerges. "Smart" pixel is intended to use a dual-gate photosensitive TFT for sensing, storage, and switch. It differs from a conventional passive pixel sensor (PPS) and active pixel sensor (APS) in that all these three functions are combined into one device instead of three separate units in a pixel. Thus, it is expected to have high fill factor and high spatial resolution. In addition, it utilizes the amplification effect of the dual-gate photosensitive TFT to form a one-transistor APS that leads to a potentially high SNR. This paper addresses the design, optimization and evaluation of the smart pixel sensor and array for low-dose DR. We will design and optimize the smart pixel from the scintillator to TFT levels and validate it through optical and electrical simulation and experiments of a 4x4 sensor array.

  18. GigaTracker, a Thin and Fast Silicon Pixels Tracker

    CERN Document Server

    Velghe, Bob; Bonacini, Sandro; Ceccucci, Augusto; Kaplon, Jan; Kluge, Alexander; Mapelli, Alessandro; Morel, Michel; Noël, Jérôme; Noy, Matthew; Perktold, Lukas; Petagna, Paolo; Poltorak, Karolina; Riedler, Petra; Romagnoli, Giulia; Chiozzi, Stefano; Cotta Ramusino, Angelo; Fiorini, Massimiliano; Gianoli, Alberto; Petrucci, Ferruccio; Wahl, Heinrich; Arcidiacono, Roberta; Jarron, Pierre; Marchetto, Flavio; Gil, Eduardo Cortina; Nuessle, Georg; Szilasi, Nicolas

    2014-01-01

    GigaTracker, the NA62’s upstream spectrometer, plays a key role in the kinematically constrained background suppression for the study of the K + ! p + n ̄ n decay. It is made of three independent stations, each of which is a six by three cm 2 hybrid silicon pixels detector. To meet the NA62 physics goals, GigaTracker has to address challenging requirements. The hit time resolution must be better than 200 ps while keeping the total thickness of the sensor to less than 0.5 mm silicon equivalent. The 200 μm thick sensor is divided into 18000 300 μm 300 μm pixels bump-bounded to ten independent read-out chips. The chips use an end-of-column architecture and rely on time-over- threshold discriminators. A station can handle a crossing rate of 750 MHz. Microchannel cooling technology will be used to cool the assembly. It allows us to keep the sensor close to 0 C with 130 μm of silicon in the beam area. The sensor and read-out chip performance were validated using a 45 pixel demonstrator with a laser test setu...

  19. Simulation of charge transport in pixelated CdTe

    Science.gov (United States)

    Kolstein, M.; Ariño, G.; Chmeissani, M.; De Lorenzo, G.

    2014-12-01

    The Voxel Imaging PET (VIP) Pathfinder project intends to show the advantages of using pixelated semiconductor technology for nuclear medicine applications to achieve an improved image reconstruction without efficiency loss. It proposes designs for Positron Emission Tomography (PET), Positron Emission Mammography (PEM) and Compton gamma camera detectors with a large number of signal channels (of the order of 106). The design is based on the use of a pixelated CdTe Schottky detector to have optimal energy and spatial resolution. An individual read-out channel is dedicated for each detector voxel of size 1 × 1 × 2 mm3 using an application-specific integrated circuit (ASIC) which the VIP project has designed, developed and is currently evaluating experimentally. The behaviour of the signal charge carriers in CdTe should be well understood because it has an impact on the performance of the readout channels. For this purpose the Finite Element Method (FEM) Multiphysics COMSOL software package has been used to simulate the behaviour of signal charge carriers in CdTe and extract values for the expected charge sharing depending on the impact point and bias voltage. The results on charge sharing obtained with COMSOL are combined with GAMOS, a Geant based particle tracking Monte Carlo software package, to get a full evaluation of the amount of charge sharing in pixelated CdTe for different gamma impact points.

  20. Pixel detectors from fundamentals to applications

    CERN Document Server

    Rossi, Leonardo; Rohe, Tilman; Wermes, Norbert

    2006-01-01

    Pixel detectors are a particularly important class of particle and radiation detection devices. They have an extremely broad spectrum of applications, ranging from high-energy physics to the photo cameras of everyday life. This book is a general purpose introduction into the fundamental principles of pixel detector technology and semiconductor-based hybrid pixel devices. Although these devices were developed for high-energy ionizing particles and radiation beyond visible light, they are finding new applications in many other areas. This book will therefore benefit all scientists and engineers working in any laboratory involved in developing or using particle detection.

  1. High resolution infrared synchrotron study of CH2D81Br: ground state constants and analysis of the ν5, ν6 and ν9 fundamentals

    DEFF Research Database (Denmark)

    Baldacci, A.; Stoppa, P.; Visinoni, R.

    2012-01-01

    The high resolution infrared absorption spectrum of CH2D81Br has been recorded by Fourier transform spectroscopy in the range 550–1075 cm1, with an unapodized resolution of 0.0025 cm-1, employing a synchrotron radiation source. This spectral region is characterized by the ν6 (593.872 cm-1), ν5 (768...

  2. High throughput optoelectronic smart pixel systems using diffractive optics

    Science.gov (United States)

    Chen, Chih-Hao

    1999-12-01

    Recent developments in digital video, multimedia technology and data networks have greatly increased the demand for high bandwidth communication channels and high throughput data processing. Electronics is particularly suited for switching, amplification and logic functions, while optics is more suitable for interconnections and communications with lower energy and crosstalk. In this research, we present the design, testing, integration and demonstration of several optoelectronic smart pixel devices and system architectures. These systems integrate electronic switching/processing capability with parallel optical interconnections to provide high throughput network communication and pipeline data processing. The Smart Pixel Array Cellular Logic processor (SPARCL) is designed in 0.8 m m CMOS and hybrid integrated with Multiple-Quantum-Well (MQW) devices for pipeline image processing. The Smart Pixel Network Interface (SAPIENT) is designed in 0.6 m m GaAs and monolithically integrated with LEDs to implement a highly parallel optical interconnection network. The Translucent Smart Pixel Array (TRANSPAR) design is implemented in two different versions. The first version, TRANSPAR-MQW, is designed in 0.5 m m CMOS and flip-chip integrated with MQW devices to provide 2-D pipeline processing and translucent networking using the Carrier- Sense-MultipleAccess/Collision-Detection (CSMA/CD) protocol. The other version, TRANSPAR-VM, is designed in 1.2 m m CMOS and discretely integrated with VCSEL-MSM (Vertical-Cavity-Surface- Emitting-Laser and Metal-Semiconductor-Metal detectors) chips and driver/receiver chips on a printed circuit board. The TRANSPAR-VM provides an option of using the token ring network protocol in addition to the embedded functions of TRANSPAR-MQW. These optoelectronic smart pixel systems also require micro-optics devices to provide high resolution, high quality optical interconnections and external source arrays. In this research, we describe an innovative

  3. Performance of silicon pixel detectors at small track incidence angles for the ATLAS Inner Tracker upgrade

    Science.gov (United States)

    Viel, Simon; Banerjee, Swagato; Brandt, Gerhard; Carney, Rebecca; Garcia-Sciveres, Maurice; Hard, Andrew Straiton; Kaplan, Laser Seymour; Kashif, Lashkar; Pranko, Aliaksandr; Rieger, Julia; Wolf, Julian; Wu, Sau Lan; Yang, Hongtao

    2016-09-01

    In order to enable the ATLAS experiment to successfully track charged particles produced in high-energy collisions at the High-Luminosity Large Hadron Collider, the current ATLAS Inner Detector will be replaced by the Inner Tracker (ITk), entirely composed of silicon pixel and strip detectors. An extension of the tracking coverage of the ITk to very forward pseudorapidity values is proposed, using pixel modules placed in a long cylindrical layer around the beam pipe. The measurement of long pixel clusters, detected when charged particles cross the silicon sensor at small incidence angles, has potential to significantly improve the tracking efficiency, fake track rejection, and resolution of the ITk in the very forward region. The performance of state-of-the-art pixel modules at small track incidence angles is studied using test beam data collected at SLAC and CERN.

  4. Small-Scale Readout System Prototype for the STAR PIXEL Detector

    Energy Technology Data Exchange (ETDEWEB)

    Szelezniak, Michal; Anderssen, Eric; Greiner, Leo; Matis, Howard; Ritter, Hans Georg; Stezelberger, Thorsten; Sun, Xiangming; Thomas, James; Vu, Chinh; Wieman, Howard

    2008-10-10

    Development and prototyping efforts directed towards construction of a new vertex detector for the STAR experiment at the RHIC accelerator at BNL are presented. This new detector will extend the physics range of STAR by allowing for precision measurements of yields and spectra of particles containing heavy quarks. The innermost central part of the new detector is a high resolution pixel-type detector (PIXEL). PIXEL requirements are discussed as well as a conceptual mechanical design, a sensor development path, and a detector readout architecture. Selected progress with sensor prototypes dedicated to the PIXEL detector is summarized and the approach chosen for the readout system architecture validated in tests of hardware prototypes is discussed.

  5. ASICs in nanometer and 3D technologies for readout of hybrid pixel detectors

    Science.gov (United States)

    Maj, Piotr; Grybos, Pawel; Kmon, Piotr; Szczygiel, Robert

    2013-07-01

    Hybrid pixel detectors working in a single photon counting mode are very attractive solutions for material science and medical X-ray imaging applications. Readout electronics of these detectors has to match the geometry of pixel detectors with an area of readout channel of 100 μm × 100 μm (or even less) and very small power consumption (a few tens of μW). New solutions of readout ASICs are going into directions of better spatial resolutions, higher data throughput and more advanced functionality. We report on the design and measurement results of two pixel prototype ASICs in nanometer technology and 3D technology which offer fast signal processing, low noise performance and advanced functionality per single readout pixel cell.

  6. Performance of Silicon Pixel Detectors at Small Track Incidence Angles for the ATLAS Inner Tracker Upgrade

    CERN Document Server

    Viel, Simon; The ATLAS collaboration; Brandt, Gerhard; Carney, Rebecca; Garcia-Sciveres, Maurice; Hard, Andrew; Kaplan, Laser Seymour; Kashif, Lashkar; Pranko, Aliaksandr; Rieger, Julia; Wolf, Julian Choate; Wu, Sau Lan; Yang, Hongtao

    2015-01-01

    In order to enable the ATLAS experiment to successfully track charged particles produced in high-energy collisions at the High-Luminosity Large Hadron Collider, the current ATLAS Inner Detector will be replaced by the Inner Tracker (ITk), entirely composed of silicon pixel and strip detectors. An extension of the tracking coverage of the ITk to very forward pseudorapidity values is proposed, using pixel modules placed in a long cylindrical layer around the beam pipe. The measurement of long pixel clusters, detected when charged particles cross the silicon sensor at small incidence angles, has potential to significantly improve the tracking efficiency, fake track rejection, and resolution of the ITk in the very forward region. The performance of state-of-the-art pixel modules at small track incidence angles is studied using test beam data collected at SLAC and CERN.

  7. Adopt a Pixel Photographs: 2013-Present

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The photographs in the Adopt a Pixel collection were provided by volunteers with a digital camera, a Global Positioning System (GPS), and a compass or a smart mobile...

  8. Adopt a Pixel Photographs: 2013-Present

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The photographs in the Adopt a Pixel collection were provided by volunteers with a digital camera, a Global Positioning System (GPS), and a compass or a smart mobile...

  9. Adopt a Pixel Photographs: 2013-Present

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The photographs in the Adopt a Pixel collection were provided by volunteers with a digital camera, a Global Positioning System (GPS), and a compass or a smart...

  10. Beam test characterization of CMS silicon pixel detectors for the phase-1 upgrade

    Science.gov (United States)

    Korol, I.

    2015-10-01

    The Silicon Pixel Detector forms the innermost part of the CMS tracking system and is critical to track and vertex reconstruction. Being in close proximity to the beam interaction point, it is exposed to the highest radiation levels in the silicon tracker. In order to preserve the tracking performance with the LHC luminosity increase which is foreseen for the next years, the CMS collaboration has decided to build a new pixel detector with four barrel layers mounted around a reduced diameter beam pipe, as compared to the present three layer pixel detector in the central region. A new digital version of the front-end readout chip has been designed and tested; it has increased data buffering and readout link speed to maintain high efficiency at increasing occupancy. In addition, it offers lower charge thresholds that will improve the tracking efficiency and position resolution. Single chip modules have been evaluated in the DESY electron test beam in terms of charge collection, noise, tracking efficiency and position resolution before and after irradiation with 24 GeV protons from the CERN Proton Synchroton equivalent to the fluence expected after 500 fb-1 of integrated luminosity in the fourth layer of the pixel tracker. High efficiency and an excellent position resolution have been observed which are well maintained even after the proton irradiation. The results are well described by the CMS pixel detector simulation.

  11. Retrievals of ethane from ground-based high-resolution FTIR solar observations with updated line parameters: determination of the optimum strategy for the Jungfraujoch station.

    Science.gov (United States)

    Bader, W.; Perrin, A.; Jacquemart, D.; Sudo, K.; Yashiro, H.; Gauss, M.; Demoulin, P.; Servais, C.; Mahieu, E.

    2012-04-01

    Ethane (C2H6) is the most abundant Non-Methane HydroCarbon (NMHC) in the Earth's atmosphere, with a lifetime of approximately 2 months. C2H6 has both anthropogenic and natural emission sources such as biomass burning, natural gas loss and biofuel consumption. Oxidation by the hydroxyl radical is by far the major C2H6 sink as the seasonally changing OH concentration controls the strong modulation of the ethane abundance throughout the year. Ethane lowers Cl atom concentrations in the lower stratosphere and is a major source of peroxyacetyl nitrate (PAN) and carbon monoxide (by reaction with OH). Involved in the formation of tropospheric ozone and in the destruction of atmospheric methane through changes in OH, C2H6 is a non-direct greenhouse gas with a net-global warming potential (100-yr horizon) of 5.5. The retrieval of ethane from ground-based infrared (IR) spectra is challenging. Indeed, the fitting of the ethane features is complicated by numerous interferences by strong water vapor, ozone and methane absorptions. Moreover, ethane has a complicated spectrum with many interacting vibrational modes and the current state of ethane parameters in HITRAN (e.g. : Rothman et al., 2009, see http://www.hitran.com) was rather unsatisfactory in the 3 μm region. In fact, PQ branches outside the 2973-3001 cm-1 range are not included in HITRAN, and most P and R structures are missing. New ethane absorption cross sections recorded at the Molecular Spectroscopy Facility of the Rutherford Appleton Laboratory (Harrison et al., 2010) are used in our retrievals. They were calibrated in intensity by using reference low-resolution spectra from the Pacific Northwest National Laboratory (PNNL) IR database. Pseudoline parameters fitted to these ethane spectra have been combined with HITRAN 2004 line parameters (including all the 2006 updates) for all other species encompassed in the selected microwindows. Also, the improvement brought by the update of the line positions and intensities

  12. Synthetic aperture radar images with composite azimuth resolution

    Energy Technology Data Exchange (ETDEWEB)

    Bielek, Timothy P; Bickel, Douglas L

    2015-03-31

    A synthetic aperture radar (SAR) image is produced by using all phase histories of a set of phase histories to produce a first pixel array having a first azimuth resolution, and using less than all phase histories of the set to produce a second pixel array having a second azimuth resolution that is coarser than the first azimuth resolution. The first and second pixel arrays are combined to produce a third pixel array defining a desired SAR image that shows distinct shadows of moving objects while preserving detail in stationary background clutter.

  13. Focal plane array with modular pixel array components for scalability

    Energy Technology Data Exchange (ETDEWEB)

    Kay, Randolph R; Campbell, David V; Shinde, Subhash L; Rienstra, Jeffrey L; Serkland, Darwin K; Holmes, Michael L

    2014-12-09

    A modular, scalable focal plane array is provided as an array of integrated circuit dice, wherein each die includes a given amount of modular pixel array circuitry. The array of dice effectively multiplies the amount of modular pixel array circuitry to produce a larger pixel array without increasing die size. Desired pixel pitch across the enlarged pixel array is preserved by forming die stacks with each pixel array circuitry die stacked on a separate die that contains the corresponding signal processing circuitry. Techniques for die stack interconnections and die stack placement are implemented to ensure that the desired pixel pitch is preserved across the enlarged pixel array.

  14. Change detection of built-up land: A framework of combining pixel-based detection and object-based recognition

    Science.gov (United States)

    Xiao, Pengfeng; Zhang, Xueliang; Wang, Dongguang; Yuan, Min; Feng, Xuezhi; Kelly, Maggi

    2016-09-01

    This study proposed a new framework that combines pixel-level change detection and object-level recognition to detect changes of built-up land from high-spatial resolution remote sensing images. First, an adaptive differencing method was designed to detect changes at the pixel level based on both spectral and textural features. Next, the changed pixels were subjected to a set of morphological operations to improve the completeness and to generate changed objects, achieving the transition of change detection from the pixel level to the object level. The changed objects were further recognised through the difference of morphological building index in two phases to indicate changed objects on built-up land. The transformation from changed pixels to changed objects makes the proposed framework distinct with both the pixel-based and the object-based change detection methods. Compared with the pixel-based methods, the proposed framework can improve the change detection capability through the transformation and successive recognition of objects. Compared with the object-based method, the proposed framework avoids the issue of multitemporal segmentation and can generate changed objects directly from changed pixels. The experimental results show the effectiveness of the transformation from changed pixels to changed objects and the successive object-based recognition on improving the detection accuracy, which justify the application potential of the proposed change detection framework.

  15. Region based elimination of noise pixels towards optimized classifier models for skin pixel detection

    Directory of Open Access Journals (Sweden)

    Gagandeep Kaur

    2015-03-01

    Full Text Available The extraction of the skin pixels in a human image and rejection of non-skin pixels is called the skin segmentation. Skin pixel detection is the process of extracting the skin pixels in a human image which is typically used as a pre-processing step to extract the face regions from human image. In past, there are several computer vision approaches and techniques have been developed for skin pixel detection. In the process of skin detection, given pixels are been transformed into an appropriate color space such as RGB, HSV etc. And then skin classifier model have been applied to label the pixel into skin or non-skin regions. Here in this research a “Region based elimination of noise pixels and performance analysis of classifier models for skin pixel detection applied on human images” would be performed which involve the process of image representation in color models, elimination of non-skin pixels in the image, and then pre-processing and cleansing of the collected data, feature selection of the human image and then building the model for classifier. In this research and implementation of skin pixels classifier models are proposed with their comparative performance analysis. The definition of the feature vector is simply the selection of skin pixels from the human image or stack of human images. The performance is evaluated by comparing and analysing skin colour segmentation algorithms. During the course of research implementation, efforts are iterative which help in selection of optimized skin classifier based on the machine learning algorithms and their performance analysis.

  16. Study of silicon pixel sensor for synchrotron radiation detection

    Science.gov (United States)

    Li, Zhen-Jie; Jia, Yun-Cong; Hu, Ling-Fei; Liu, Peng; Yin, Hua-Xiang

    2016-03-01

    The silicon pixel sensor (SPS) is one of the key components of hybrid pixel single-photon-counting detectors for synchrotron radiation X-ray detection (SRD). In this paper, the design, fabrication, and characterization of SPSs for single beam X-ray photon detection is reported. The designed pixel sensor is a p+-in-n structure with guard-ring structures operated in full-depletion mode and is fabricated on 4-inch, N type, 320 μm thick, high-resistivity silicon wafers by a general Si planar process. To achieve high energy resolution of X-rays and obtain low dark current and high breakdown voltage as well as appropriate depletion voltage of the SPS, a series of technical optimizations of device structure and fabrication process are explored. With optimized device structure and fabrication process, excellent SPS characteristics with dark current of 2 nA/cm2, full depletion voltage 150 V are achieved. The fabricated SPSs are wire bonded to ASIC circuits and tested for the performance of X-ray response to the 1W2B synchrotron beam line of the Beijing Synchrotron Radiation Facility. The measured S-curves for SRD demonstrate a high discrimination for different energy X-rays. The extracted energy resolution is high (10 keV) and the linear properties between input photo energy and the equivalent generator amplitude are well established. It confirmed that the fabricated SPSs have a good energy linearity and high count rate with the optimized technologies. The technology is expected to have a promising application in the development of a large scale SRD system for the Beijing Advanced Photon Source. Supported by Prefabrication Research of Beijing Advanced Photon Source (R&D for BAPS) and National Natural Science Foundation of China (11335010)

  17. Single-pixel camera with one graphene photodetector.

    Science.gov (United States)

    Li, Gongxin; Wang, Wenxue; Wang, Yuechao; Yang, Wenguang; Liu, Lianqing

    2016-01-11

    Consumer cameras in the megapixel range are ubiquitous, but the improvement of them is hindered by the poor performance and high cost of traditional photodetectors. Graphene, a two-dimensional micro-/nano-material, recently has exhibited exceptional properties as a sensing element in a photodetector over traditional materials. However, it is difficult to fabricate a large-scale array of graphene photodetectors to replace the traditional photodetector array. To take full advantage of the unique characteristics of the graphene photodetector, in this study we integrated a graphene photodetector in a single-pixel camera based on compressive sensing. To begin with, we introduced a method called laser scribing for fabrication the graphene. It produces the graphene components in arbitrary patterns more quickly without photoresist contamination as do traditional methods. Next, we proposed a system for calibrating the optoelectrical properties of micro/nano photodetectors based on a digital micromirror device (DMD), which changes the light intensity by controlling the number of individual micromirrors positioned at + 12°. The calibration sensitivity is driven by the sum of all micromirrors of the DMD and can be as high as 10(-5)A/W. Finally, the single-pixel camera integrated with one graphene photodetector was used to recover a static image to demonstrate the feasibility of the single-pixel imaging system with the graphene photodetector. A high-resolution image can be recovered with the camera at a sampling rate much less than Nyquist rate. The study was the first demonstration for ever record of a macroscopic camera with a graphene photodetector. The camera has the potential for high-speed and high-resolution imaging at much less cost than traditional megapixel cameras.

  18. How spectroscopic x-ray imaging benefits from inter-pixel communication

    CERN Document Server

    Koenig, Thomas; Hamann, Elias; Cecilia, Angelica; Ballabriga, Rafael; Campbell, Michael; Ruat, Marie; Tlustos, Lukas; Fauler, Alex; Fiederle, Michael; Baumbach, Tilo

    2014-01-01

    Spectroscopic x-ray imaging based on pixellated semiconductor detectors can be sensitive to charge sharing and K-fluorescence, depending on the sensor material used, its thickness and the pixel pitch employed. As a consequence, spectroscopic resolution is partially lost. In this paper, we study a new detector ASIC, the Medipix3RX, that offers a novel feature called charge summing, which is established by making adjacent pixels communicate with each other. Consequently, single photon interactions resulting in multiple hits are almost completely avoided. We investigate this charge summing mode with respect to those of its imaging properties that are of interest in medical physics and benchmark them against the case without charge summing. In particular, we review its influence on spectroscopic resolution and find that the low energy bias normally present when recording energy spectra is dramatically reduced. Furthermore, we show that charge summing provides a modulation transfer function which is almost indepen...

  19. Performance Characteristics of Pixelated CZT Crystals used on the GammaTracker Project

    Energy Technology Data Exchange (ETDEWEB)

    Becker, Eric M.; Seifert, Carolyn E.; Myjak, Mitchell J.; Erikson, Luke E.; Morris, Scott J.; Balvage, Duane R.; Lundy, Richard P.

    2011-08-21

    GammaTracker is a handheld radioisotope identification device in development at Pacific Northwest National Laboratory that uses eighteen pixelated Cadmium-Zinc Telluride (CZT) crystals to provide energy resolution approaching that of high-purity germanium without the need for cryogenic cooling. Additionally, these crystals can be used to provide directional and imaging capabilities that cannot be found in other handheld detectors. A significant number of CZT crystals have been procured during the development of the GammaTracker system; the majority of these were procured with the same set of specifications. Each of these detectors has been characterized in terms of key parameters, including current-voltage response and pixel-by-pixel energy resolution. The results of this testing indicate that the overall quality of CZT crystals is improving over time.

  20. First operation of a pixel imaging matrix based on DEPFET pixels

    CERN Document Server

    Fischer, P; Klein, P; Löcker, M; Lutz, Gerhard; Neeser, W; Strüder, L; Wermes, N

    2000-01-01

    In the DEPFET pixel concept the detected incident radiation is directly sensed and amplified by a JFET integrated in every pixel cell. While the DEPFET detector principle has already been demonstrated previously on single pixel structures, we present here the first successful operation of a large $32 \\times 32$ DEPFET pixel matrix as an imaging device. The matrix has been exposed to 60 keV gamma rays of a $^{241}$Am source and has been scanned using an IR laser. The principle of operation as well as the charge collection in the structure and possible improvements are discussed.

  1. Spatial clustering of pixels of a multispectral image

    Energy Technology Data Exchange (ETDEWEB)

    Conger, James Lynn

    2014-08-19

    A method and system for clustering the pixels of a multispectral image is provided. A clustering system computes a maximum spectral similarity score for each pixel that indicates the similarity between that pixel and the most similar neighboring. To determine the maximum similarity score for a pixel, the clustering system generates a similarity score between that pixel and each of its neighboring pixels and then selects the similarity score that represents the highest similarity as the maximum similarity score. The clustering system may apply a filtering criterion based on the maximum similarity score so that pixels with similarity scores below a minimum threshold are not clustered. The clustering system changes the current pixel values of the pixels in a cluster based on an averaging of the original pixel values of the pixels in the cluster.

  2. Spatial clustering of pixels of a multispectral image

    Science.gov (United States)

    Conger, James Lynn

    2014-08-19

    A method and system for clustering the pixels of a multispectral image is provided. A clustering system computes a maximum spectral similarity score for each pixel that indicates the similarity between that pixel and the most similar neighboring. To determine the maximum similarity score for a pixel, the clustering system generates a similarity score between that pixel and each of its neighboring pixels and then selects the similarity score that represents the highest similarity as the maximum similarity score. The clustering system may apply a filtering criterion based on the maximum similarity score so that pixels with similarity scores below a minimum threshold are not clustered. The clustering system changes the current pixel values of the pixels in a cluster based on an averaging of the original pixel values of the pixels in the cluster.

  3. Per pixel uncertainty modelling and its spatial representation on land cover maps obtained by hybrid classification.

    Science.gov (United States)

    Pons, Xavier; Sevillano, Eva; Moré, Gerard; Serra, Pere; Cornford, Dan; Ninyerola, Miquel

    2013-04-01

    The usage of remote sensing imagery combined with statistical classifiers to obtain categorical cartography is now common practice. As in many other areas of geographic information quality assessment, knowing the accuracy of these maps is crucial, and the spatialization of quality information is becoming ever more important for a large range of applications. Whereas some classifiers (e.g., maximum likelihood, linear discriminant analysis, naive Bayes, etc) permit the estimation and spatial representation of the uncertainty through a pixel level probabilistic estimator (and, from that, to compute a global accuracy estimator for the whole map), for other methods such a direct estimator does not exist. Regardless of the classification method applied, ground truth data is almost always available (to train the classifier and/or to compute the global accuracy and, usually, a confusion matrix). Our research is devoted to the development of a protocol to spatialize the error on a general framework based on the classifier parameters, and some ground truth reference data. In the methodological experiment presented here we provide an insight into uncertainty modelling for a hybrid classifier that combines unsupervised and supervised stages (implemented in the MiraMon GIS). In this work we describe what we believe is the first attempt to characterise pixel level uncertainty in a two stage classification process. We describe the model setup, show the preliminary results and identify future work that will be undertaken. The study area is a Landsat full frame located at the North-eastern region of the Iberian Peninsula. The six non-thermal bands + NDVI of a multi-temporal set of six geometrically and radiometrically corrected Landsat-5 images (between 2005 and 2007) were submitted to a hybrid classification process, together with some ancillary data (climate, slopes, etc). Training areas were extracted from the Land Cover Map of Catalonia (MCSC), a 0.5 m resolution map created by

  4. Investigation of photon counting pixel detectors for X-ray spectroscopy and imaging

    Energy Technology Data Exchange (ETDEWEB)

    Talla, Patrick Takoukam

    2011-04-07

    important for quality assurance and constancy checks in hospitals. The second part of the thesis is about the imaging properties of the Medipix detectors. Images of samples (cash card, human bone) were taken with the Medipix3 chip in Single Pixel Mode (equivalent to the counting mode of the Medipix2 detector) and in Charge Summing Mode. The images in Single Pixel Mode were sharper than the ones taken in Charge Summing Mode. The latter show high granularity. This is due to high pixel-to-pixel variation in threshold in Charge Summing Mode. A redesign of the Medipix3 detector is proposed in order to correct for this problem. The determination of the spatial resolution confirms that Single Pixel Mode is better for imaging. Energy resolved material reconstruction was also performed with Medipix3 programmed in Single Pixel Mode and Charge Summing Mode. The combination method was applied to determine the concentration of elements in a compound object. The Downhill Simplex and Simulated Annealing methods were used to minimize the likelihood function delivered by the combination method. In a first step, the reconstruction method was tested using simulated data. The results of the reconstruction show that the reconstruction is better in Charge Summing Mode than in Single Pixel Mode. The method of material reconstruction was also applied with success to data taken with the Medipix3 detector programmed in Single Pixel Mode. In summary, the Medipix detectors were successfully used in spectroscopy and imaging. An improvement of Charge Summing Mode of Medipix3 is necessary in order to reach at least the same image quality as in Single Pixel Mode. (orig.)

  5. First retrievals of HCFC-142b from ground-based high-resolution FTIR solar observations: application to high-altitude Jungfraujoch spectra

    Science.gov (United States)

    Mahieu, Emmanuel; O'Doherty, Simon; Reimann, Stefan; Vollmer, Martin; Bader, Whitney; Bovy, Benoît; Lejeune, Bernard; Demoulin, Philippe; Roland, Ginette; Servais, Christian; Zander, Rodolphe

    2013-04-01

    Hydrofluorocarbons (HCFCs) are the first substitutes to the long-lived ozone depleting halocarbons, in particular the chlorofluorocarbons (CFCs). Given the complete ban of the CFCs by the Montreal Protocol, its Amendments and Adjustments, HCFCs are on the rise, with current rates of increase substantially larger than at the beginning of the 21st century. HCFC-142b (CH3CClF2) is presently the second most abundant HCFCs, after HCFC-22 (CHClF2). It is used in a wide range of applications, including as a blowing foam agent, in refrigeration and air-conditioning. Its concentration will soon reach 25 ppt in the northern hemisphere, with mixing ratios increasing at about 1.1 ppt/yr [Montzka et al., 2011]. The HCFC-142b lifetime is estimated at 18 years. With a global warming potential of 2310 on a 100-yr horizon, this species is also a potent greenhouse gas [Forster et al., 2007]. First space-based retrievals of HCFC-142b have been reported by Dufour et al. [2005]. 17 occultations recorded in 2004 by the Canadian ACE-FTS instrument (Atmospheric Chemistry Experiment - Fourier Transform Spectrometer, onboard SCISAT-1) were analyzed, using two microwindows (1132.5-1135.5 and 1191.5-1195.5 cm-1). In 2009, Rinsland et al. determined the HCFC-142b trend near the tropopause, from the analysis of ACE-FTS observations recorded over the 2004-2008 time period. The spectral region used in this study extended from 903 to 905.5 cm-1. In this contribution, we will present the first HCFC-142b measurements from ground-based high-resolution Fourier Transform Infrared (FTIR) solar spectra. We use observations recorded at the high altitude station of the Jungfraujoch (46.5°N, 8°E, 3580 m asl), with a Bruker 120HR instrument, in the framework of the Network for the Detection of Atmospheric Composition Change (NDACC, visit http://www.ndacc.org). The retrieval of HCFC-142b is very challenging, with simulations indicating only weak absorptions, lower than 1% for low sun spectra and current

  6. A logarithmic low dark current CMOS pixel

    Science.gov (United States)

    Brunetti, Alessandro Michel; Choubey, Bhaskar

    2016-04-01

    High dynamic range pixels are required in a number of automotive and scientific applications. CMOS pixels provide different approaches to achieve this. However, these suffer from poor performance under low light conditions due to inherently high leakage current that is present in CMOS processes, also known as dark current. The typical approach to reduce this dark current involves process modifications. Nevertheless, energy considerations suggest that the leakage current will be close to zero at a close to zero voltage on the photodiode. Hence, the reduction in dark current can be achieved by forcing a zero voltage across the photodiode. In this paper, a novel logarithmic CMOS pixel design capable of reducing dark current without any process modifications is proposed. This pixel is also able to produce a wide dynamic range response. This circuit utilizes two current mirrors to force the in-pixel photodiode at a close to zero voltage. Additionally, a bias voltage is used to reduce a higher order effect known as Drain Induced Barrier Lowering (DIBL). In fact, the contribution of this effect can be compensated by increasing the body effect. In this paper, we studied the consequences of a negative bias voltage applied to the body of the current mirror pair to compensate for the DIBL effect thereby achieving a very small voltage drop on the photodiode and consequently, a higher sensitivity in low light conditions.

  7. Multidimensional High Spatiotemporal Resolution InSAR Time Series Assist Interdisciplinary Space- And Ground-Based Monitoring To Reveal Pre-Eruptive Signals At Nyamulagira Volcano (North Kivu, D.R.C.)

    Science.gov (United States)

    d'Oreye, N.; Smets, B.; Kervyn, F.; Kervyn, M.; Albino, F.; Arellano, S. R.; Arjona, A. A.; Carn, S. A.; Fernandez, J.; Galle, B.; Gonzalez, P. J.; Head, E.; Pallero, J.; Prieto, J. F.; Samsonov, S. V.; Tedesco, D.; Tiampo, K. F.; Wauthier, C.

    2013-12-01

    Interdisciplinary space- and ground-based monitoring systems allowed the quantitative and detailed study of the Nyamulagira 2010 eruption (Congo). Field observations revealed the event as 4 eruptive phases delimited by major changes in effusive activity. Signals from ground deformation, seismicity, SO2 emission and thermal flux correlate with these eruptive phases. Moreover, MSBAS InSAR time series combining data acquired under different geometries and with different satellites (Samsonov and d'Oreye, 2012) allowed the detection of pre-, co- and inter-eruptive deformation in the Nyamulagira volcanic field. Using 8 years of ENVISAT, RADARSAT2 and ALOS data, the MSBAS method reveals the first unambiguous pre-eruptive ground deformations in the Virunga Volcanic Province. Precursory ground deformations are detected up to 3 weeks prior the onset of the 2010 eruption by images acquired by 3 different sensors in different geometries. These deformations took place in the main crater and along the SE flank of the volcano, where eruptive fractures will ultimately opened. Deformations coincide with small, though clear, increase of the short period seismicity and SO2 emissions.These seismic and SO2 variations alone were too small, however, to raise attention. The pre-eruptive ground deformation signals revealed by InSAR are of about the same amplitude and spatial extent as atmospheric noise and therefore cannot be identified on individual differential interferograms. Conventional time-series methods based on single acquisition geometry do not have a sufficient time resolution to discriminate such a precursory signal from an atmospheric artifact. The 3-week precursors detected at Nyamulagira contrast with the only precursory signal previously recognized so far in the Virunga, namely the increase of tremors and long period seismicity no more than few hours or days before the eruption onset. In January 2010, such short-term seismic precursors were detected less than two hours

  8. Determining the Pixel-to-Pixel Uncertainty in Satellite-Derived SST Fields

    Directory of Open Access Journals (Sweden)

    Fan Wu

    2017-08-01

    Full Text Available The primary measure of the quality of sea surface temperature (SST fields obtained from satellite-borne infrared sensors has been the bias and variance of matchups with co-located in-situ values. Because such matchups tend to be widely separated, these bias and variance estimates are not necessarily a good measure of small scale (several pixels gradients in these fields because one of the primary contributors to the uncertainty in satellite retrievals is atmospheric contamination, which tends to have large spatial scales compared with the pixel separation of infrared sensors. Hence, there is not a good measure to use in selecting SST fields appropriate for the study of submesoscale processes and, in particular, of processes associated with near-surface fronts, both of which have recently seen a rapid increase in interest. In this study, two methods are examined to address this problem, one based on spectra of the SST data and the other on their variograms. To evaluate the methods, instrument noise was estimated in Level-2 Visible-Infrared Imager-Radiometer Suite (VIIRS and Advanced Very High Resolution Radiometer (AVHRR SST fields of the Sargasso Sea. The two methods provided very nearly identical results for AVHRR: along-scan values of approximately 0.18 K for both day and night and along-track values of 0.21 K for day and night. By contrast, the instrument noise estimated for VIIRS varied by method, scan geometry and day-night. Specifically, daytime, along-scan (along-track, spectral estimates were found to be approximately 0.05 K (0.08 K and the corresponding nighttime values of 0.02 K (0.03 K. Daytime estimates based on the variogram were found to be 0.08 K (0.10 K with the corresponding nighttime values of 0.04 K (0.06 K. Taken together, AVHRR instrument noise is significantly larger than VIIRS instrument noise, along-track noise is larger than along-scan noise and daytime levels are higher than nighttime levels. Given the similarity of

  9. Characterisation of a single photon counting pixel system for imaging of low-contrast objects

    CERN Document Server

    Mikulec, B; Dipasquale, G; Schwarz, C; Watt, J

    2001-01-01

    In the framework of the Medipix collaboration the PCC, a single photon counting pixel chip, has been developed with the aim of improving the contrast resolution in medical imaging applications. The PCC consists of a matrix of 64x64 square pixels with 170 mm side length, each pixel comprising a 15 bit counter and a pulse height discriminator. The chip has been bump bonded to equally segmented 200 mm thick SI-LEC GaAs detectors showing a very high absorption energy for X-rays used in diagnostics. An absolute calibration of the system with a radioactive source and a synchrotron beam are described resulting in the value of the test input capacitance of ~24.7 fF. Using this value a full characterisation of the system from electrical measurements is presented. The entire system can reach a minimum threshold of ~2100 e- with ~250e- rms noise. One of the characteristics of the PCC is the possibility to adjust the thresholds of all pixels on a pixel-by-pixel basis with 3-bit precision. The threshold distribution after...

  10. Efficient phase contrast imaging in STEM using a pixelated detector. Part II: Optimisation of imaging conditions

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Hao, E-mail: hao.yang@materials.ox.ac.uk [University of Oxford, Department of Materials. Parks Rd, Oxford OX1 3PH (United Kingdom); Pennycook, Timothy J.; Nellist, Peter D. [University of Oxford, Department of Materials. Parks Rd, Oxford OX1 3PH (United Kingdom); EPSRC SuperSTEM Facility, Daresbury Laboratory, WA4 4AD (United Kingdom)

    2015-04-15

    In Part I of this series of two papers, we demonstrated the formation of a high efficiency phase-contrast image at atomic resolution using a pixelated detector in the scanning transmission electron microscope (STEM) with ptychography. In this paper we explore the technique more quantitatively using theory and simulations. Compared to other STEM phase contrast modes including annular bright field (ABF) and differential phase contrast (DPC), we show that the ptychographic phase reconstruction method using pixelated detectors offers the highest contrast transfer efficiency and superior low dose performance. Applying the ptychographic reconstruction method to DPC segmented detectors also improves the detector contrast transfer and results in less noisy images than DPC images formed using difference signals. We also find that using a minimum array of 16×16 pixels is sufficient to provide the highest signal-to-noise ratio (SNR) for imaging beam sensitive weak phase objects. Finally, the convergence angle can be adjusted to enhance the contrast transfer based on the spatial frequencies of the specimen under study. - Highlights: • High efficiency phase contrast transfer function (PCTF) can be achieved using pixelated detectors followed by a ptychographic reconstruction. • Ptychographic reconstruction offers the highest PCTF across the entire spatial frequency range compared to DPC and ABF. • Image simulations show that a ptychographic reconstruction using pixelated detectors offers a superior low dose performance for imaging weak phase objects. • Optimisation of imaging conditions using pixelated detectors are discussed by considering the contrast transfer function for various cases.

  11. Radiation Tolerance of CMOS Monolithic Active Pixel Sensors with Self-Biased Pixels

    CERN Document Server

    Deveaux, M; Besson, A; Claus, G; Colledani, C; Dorokhov, M; Dritsa, C; Dulinski, W; Fröhlich, I; Goffe, M; Grandjean, D; Heini, S; Himmi, A; Hu, C; Jaaskelainen, K; Müntz, C; Shabetai, A; Stroth, J; Szelezniak, M; Valin, I; Winter, M

    2009-01-01

    CMOS Monolithic Active Pixel Sensors (MAPS) are proposed as a technology for various vertex detectors in nuclear and particle physics. We discuss the mechanisms of ionizing radiation damage on MAPS hosting the the dead time free, so-called self bias pixel. Moreover, we discuss radiation hardened sensor designs which allow operating detectors after exposing them to irradiation doses above 1 Mrad

  12. M.i.p. detection performances of a 100 us read-out CMOS pixel sensor with digitised outputs

    CERN Document Server

    Winter, Marc; Besson, Auguste; Colledani, Claude; Degerli, Yavuz; De Masi, Rita; Dorokhov, Andrei; Doziere, Guy; Dulinski, Wojciech; Gelin, Marie; Guilloux, Fabrice; Himmi, Abdelkader; Hu-Guo, Christine; Morel, Frederic; Orsini, Fabienne; Valin, Isabelle; Voutsinas, Georgios

    2009-01-01

    Swift, high resolution CMOS pixel sensors are being developed for the ILC vertex detector, aiming to allow approaching the interaction point very closely. A major issue is the time resolution of the sensors needed to deal with the high occupancy generated by the beam related background. A 128x576 pixel sensor providing digitised outputs at a read-out time of 92.5 us, was fabricated in 2008 within the EU project EUDET, and tested with charged particles at the CERN-SPS. Its prominent performances in terms of noise, detection efficiency versus fake hit rate, spatial resolution and radiation tolerance are overviewed. They validate the sensor architecture.

  13. Direct charge sharing observation in single-photon-counting pixel detector

    Energy Technology Data Exchange (ETDEWEB)

    Pellegrini, G. [Centro Nacional de Microelectronica, IMB-CNM (CSIC), Barcelona 08193 (Spain)]. E-mail: Giulio.Pellegrini@cnm.es; Maiorino, M. [IFAE - Institut de Fisica d' Altes Energies, UAB Campus, 08193 Bellaterra (Spain); Blanchot, G. [IFAE - Institut de Fisica d' Altes Energies, UAB Campus, 08193 Bellaterra (Spain); Chmeissani, M. [IFAE - Institut de Fisica d' Altes Energies, UAB Campus, 08193 Bellaterra (Spain); Garcia, J. [IFAE - Institut de Fisica d' Altes Energies, UAB Campus, 08193 Bellaterra (Spain); Lozano, M. [Centro Nacional de Microelectronica, IMB-CNM (CSIC), Barcelona 08193 (Spain); Martinez, R. [Centro Nacional de Microelectronica, IMB-CNM (CSIC), Barcelona 08193 (Spain); Puigdengoles, C. [IFAE - Institut de Fisica d' Altes Energies, UAB Campus, 08193 Bellaterra (Spain); Ullan, M. [Centro Nacional de Microelectronica, IMB-CNM (CSIC), Barcelona 08193 (Spain)

    2007-04-01

    In photon-counting imaging devices, charge sharing can limit the detector spatial resolution and contrast, as multiple counts can be induced in adjacent pixels as a result of the spread of the charge cloud generated from a single X-ray photon of high energy in the detector bulk. Although debated for a long time, the full impact of charge sharing has not been completely assessed. In this work, the importance of charge sharing in pixellated CdTe and silicon detectors is studied by exposing imaging devices to different low activity sources. These devices are made of Si and CdTe pixel detector bump-bonded to Medipix2 single-photon-counting chips with a 55 {mu}m pixel pitch. We will show how charge sharing affects the spatial detector resolution depending on incident particle type (alpha, beta and gamma), detector bias voltage and read-out chip threshold. This study will give an insight on the impact on the design and operation of pixel detectors coupled to photon-counting devices for imaging applications.

  14. Direct charge sharing observation in single-photon-counting pixel detector

    Science.gov (United States)

    Pellegrini, G.; Maiorino, M.; Blanchot, G.; Chmeissani, M.; Garcia, J.; Lozano, M.; Martinez, R.; Puigdengoles, C.; Ullan, M.

    2007-04-01

    In photon-counting imaging devices, charge sharing can limit the detector spatial resolution and contrast, as multiple counts can be induced in adjacent pixels as a result of the spread of the charge cloud generated from a single X-ray photon of high energy in the detector bulk. Although debated for a long time, the full impact of charge sharing has not been completely assessed. In this work, the importance of charge sharing in pixellated CdTe and silicon detectors is studied by exposing imaging devices to different low activity sources. These devices are made of Si and CdTe pixel detector bump-bonded to Medipix2 single-photon-counting chips with a 55 μm pixel pitch. We will show how charge sharing affects the spatial detector resolution depending on incident particle type (alpha, beta and gamma), detector bias voltage and read-out chip threshold. This study will give an insight on the impact on the design and operation of pixel detectors coupled to photon-counting devices for imaging applications.

  15. Scalable structural color printing using pixelated nanostructures in RGB primary colors

    Science.gov (United States)

    Jiang, Hao; Kaminska, Bozena

    2016-03-01

    Commercially available conventional color printing techniques mainly rely on patterning pigment-based pixels on a substrate. In recent years, structural colors have become increasingly important for their intrinsic advantages such as chemical stability, high resolution and color properties. However, to apply structural color pixels in printing color images for consumer-based demands remains a daunting challenge because such pixels usually require very high resolution patterning at a high speed and low cost. In this paper, we present novel color printing techniques based on micro-patterning of prefabricated nanostructure pixels in RGB primary colors. According to the micro-patterning techniques, the presented techniques are: a) solvent-free optical and thermal patterning of nanostructure pixels, b) photographic exposure through nanostructure color filters and c) inkjet printing of silver on nanostructures. These three presented techniques share some similar characteristics with popular conventional techniques, and can be considered as new-generation printing techniques evolved from their conventional counterparts. The preliminary results suggest that implementing the presented techniques, full-color images can be printed with much improved throughput than other nano-patterning techniques and imply these techniques can potentially be applied towards color production for general consumer use.

  16. Studio di un algoritmo lineare di ricostruzione analogica della posizione per il rivelatore a pixel di ATLAS

    CERN Document Server

    Arelli-Maffioli, A; Troncon, C; Lari, T

    2007-01-01

    A detailed study of spatial resolution of Atlas pixel sensors prototypes was performed. Charge interpolation was used and allowed for a significant improvement with respect to digital resolution. A simplified algorithm for charge interpolation was developed. Its application to both unirradiated and irradiated sensors is presented and discussed.

  17. Three-dimensional cascaded system analysis of a 50 µm pixel pitch wafer-scale CMOS active pixel sensor x-ray detector for digital breast tomosynthesis.

    Science.gov (United States)

    Zhao, C; Vassiljev, N; Konstantinidis, A C; Speller, R D; Kanicki, J

    2017-03-07

    High-resolution, low-noise x-ray detectors based on the complementary metal-oxide-semiconductor (CMOS) active pixel sensor (APS) technology have been developed and proposed for digital breast tomosynthesis (DBT). In this study, we evaluated the three-dimensional (3D) imaging performance of a 50 µm pixel pitch CMOS APS x-ray detector named DynAMITe (Dynamic Range Adjustable for Medical Imaging Technology). The two-dimensional (2D) angle-dependent modulation transfer function (MTF), normalized noise power spectrum (NNPS), and detective quantum efficiency (DQE) were experimentally characterized and modeled using the cascaded system analysis at oblique incident angles up to 30°. The cascaded system model was extended to the 3D spatial frequency space in combination with the filtered back-projection (FBP) reconstruction method to calculate the 3D and in-plane MTF, NNPS and DQE parameters. The results demonstrate that the beam obliquity blurs the 2D MTF and DQE in the high spatial frequency range. However, this effect can be eliminated after FBP image reconstruction. In addition, impacts of the image acquisition geometry and detector parameters were evaluated using the 3D cascaded system analysis for DBT. The result shows that a wider projection angle range (e.g.  ±30°) improves the low spatial frequency (below 5 mm(-1)) performance of the CMOS APS detector. In addition, to maintain a high spatial resolution for DBT, a focal spot size of smaller than 0.3 mm should be used. Theoretical analysis suggests that a pixelated scintillator in combination with the 50 µm pixel pitch CMOS APS detector could further improve the 3D image resolution. Finally, the 3D imaging performance of the CMOS APS and an indirect amorphous silicon (a-Si:H) thin-film transistor (TFT) passive pixel sensor (PPS) detector was simulated and compared.

  18. Three-dimensional cascaded system analysis of a 50 µm pixel pitch wafer-scale CMOS active pixel sensor x-ray detector for digital breast tomosynthesis

    Science.gov (United States)

    Zhao, C.; Vassiljev, N.; Konstantinidis, A. C.; Speller, R. D.; Kanicki, J.

    2017-03-01

    High-resolution, low-noise x-ray detectors based on the complementary metal-oxide-semiconductor (CMOS) active pixel sensor (APS) technology have been developed and proposed for digital breast tomosynthesis (DBT). In this study, we evaluated the three-dimensional (3D) imaging performance of a 50 µm pixel pitch CMOS APS x-ray detector named DynAMITe (Dynamic Range Adjustable for Medical Imaging Technology). The two-dimensional (2D) angle-dependent modulation transfer function (MTF), normalized noise power spectrum (NNPS), and detective quantum efficiency (DQE) were experimentally characterized and modeled using the cascaded system analysis at oblique incident angles up to 30°. The cascaded system model was extended to the 3D spatial frequency space in combination with the filtered back-projection (FBP) reconstruction method to calculate the 3D and in-plane MTF, NNPS and DQE parameters. The results demonstrate that the beam obliquity blurs the 2D MTF and DQE in the high spatial frequency range. However, this effect can be eliminated after FBP image reconstruction. In addition, impacts of the image acquisition geometry and detector parameters were evaluated using the 3D cascaded system analysis for DBT. The result shows that a wider projection angle range (e.g.  ±30°) improves the low spatial frequency (below 5 mm-1) performance of the CMOS APS detector. In addition, to maintain a high spatial resolution for DBT, a focal spot size of smaller than 0.3 mm should be used. Theoretical analysis suggests that a pixelated scintillator in combination with the 50 µm pixel pitch CMOS APS detector could further improve the 3D image resolution. Finally, the 3D imaging performance of the CMOS APS and an indirect amorphous silicon (a-Si:H) thin-film transistor (TFT) passive pixel sensor (PPS) detector was simulated and compared.

  19. Retrieval Using Texture Features in High Resolution Multi-spectral Satellite Imagery

    Energy Technology Data Exchange (ETDEWEB)

    Newsam, S D; Kamath, C

    2004-01-22

    Texture features have long been used in remote sensing applications to represent and retrieve image regions similar to a query region. Various representations of texture have been proposed based on the Fourier power spectrum, spatial co-occurrence, wavelets, Gabor filters, etc. These representations vary in their computational complexity and their suitability for representing different region types. Much of the work done thus far has focused on panchromatic imagery at low to moderate spatial resolutions, such as images from Landsat 1-7 which have a resolution of 15-30 m/pixel, and from SPOT 1-5 which have a resolution of 2.5-20 m/pixel. However, it is not clear which texture representation works best for the new classes of high resolution panchromatic (60-100 cm/pixel) and multi-spectral (4 bands for red, green, blue, and near infra-red at 2.4-4 m/pixel) imagery. It is also not clear how the different spectral bands should be combined. In this paper, we investigate the retrieval performance of several different texture representations using multi-spectral satellite images from IKONOS. A query-by-example framework, along with a manually chosen ground truth dataset, allows different combinations of texture representations and spectral bands to be compared. We focus on the specific problem of retrieving inhabited regions from images of urban and rural scenes. Preliminary results show that (1) the use of all spectral bands improves the retrieval performance, and (2) co-occurrence, wavelet and Gabor texture features perform comparably.

  20. Development of CMOS Pixel Sensors with digital pixel dedicated to future particle physics experiments

    Science.gov (United States)

    Zhao, W.; Wang, T.; Pham, H.; Hu-Guo, C.; Dorokhov, A.; Hu, Y.

    2014-02-01

    Two prototypes of CMOS pixel sensor with in-pixel analog to digital conversion have been developed in a 0.18 μm CIS process. The first design integrates a discriminator into each pixel within an area of 22 × 33 μm2 in order to meet the requirements of the ALICE inner tracking system (ALICE-ITS) upgrade. The second design features 3-bit charge encoding inside a 35 × 35 μm2 pixel which is motivated by the specifications of the outer layers of the ILD vertex detector (ILD-VXD). This work aims to validate the concept of in-pixel digitization which offers higher readout speed, lower power consumption and less dead zone compared with the column-level charge encoding.

  1. Towards spark-proof gaseous pixel detectors

    Science.gov (United States)

    Tsigaridas, S.; Beuzekom, M. v.; Chan, H. W.; Graaf, H. v. d.; Hartjes, F.; Heijhoff, K.; Hessey, N. P.; Prodanovic, V.

    2016-11-01

    The micro-pattern gaseous pixel detector, is a promising technology for imaging and particle tracking applications. It is a combination of a gas layer acting as detection medium and a CMOS pixelated readout-chip. As a prevention against discharges we deposit a protection layer on the chip and then integrate on top a micromegas-like amplification structure. With this technology we are able to reconstruct 3D track segments of particles passing through the gas thanks to the functionality of the chip. We have turned a Timepix3 chip into a gaseous pixel detector and tested it at the SPS at Cern. The preliminary results are promising and within the expectations. However, the spark protection layer needs further improvement to make reliable detectors. For this reason, we have created a setup for spark-testing. We present the first results obtained from the lab-measurements along with preliminary results from the testbeam.

  2. Per-Pixel Lighting Data Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Inanici, Mehlika

    2005-08-01

    This report presents a framework for per-pixel analysis of the qualitative and quantitative aspects of luminous environments. Recognizing the need for better lighting analysis capabilities and appreciating the new measurement abilities developed within the LBNL Lighting Measurement and Simulation Toolbox, ''Per-pixel Lighting Data Analysis'' project demonstrates several techniques for analyzing luminance distribution patterns, luminance ratios, adaptation luminance and glare assessment. The techniques are the syntheses of the current practices in lighting design and the unique practices that can be done with per-pixel data availability. Demonstrated analysis techniques are applicable to both computer-generated and digitally captured images (physically-based renderings and High Dynamic Range photographs).

  3. Performance of active edge pixel sensors

    Science.gov (United States)

    Bomben, M.; Ducourthial, A.; Bagolini, A.; Boscardin, M.; Bosisio, L.; Calderini, G.; D'Eramo, L.; Giacomini, G.; Marchiori, G.; Zorzi, N.; Rummler, A.; Weingarten, J.

    2017-05-01

    To cope with the High Luminosity LHC harsh conditions, the ATLAS inner tracker has to be upgraded to meet requirements in terms of radiation hardness, pile up and geometrical acceptance. The active edge technology allows to reduce the insensitive area at the border of the sensor thanks to an ion etched trench which avoids the crystal damage produced by the standard mechanical dicing process. Thin planar n-on-p pixel sensors with active edge have been designed and produced by LPNHE and FBK foundry. Two detector module prototypes, consisting of pixel sensors connected to FE-I4B readout chips, have been tested with beams at CERN and DESY. In this paper the performance of these modules are reported. In particular the lateral extension of the detection volume, beyond the pixel region, is investigated and the results show high hit efficiency also at the detector edge, even in presence of guard rings.

  4. Active Pixel Sensors: Are CCD's Dinosaurs?

    Science.gov (United States)

    Fossum, Eric R.

    1993-01-01

    Charge-coupled devices (CCD's) are presently the technology of choice for most imaging applications. In the 23 years since their invention in 1970, they have evolved to a sophisticated level of performance. However, as with all technologies, we can be certain that they will be supplanted someday. In this paper, the Active Pixel Sensor (APS) technology is explored as a possible successor to the CCD. An active pixel is defined as a detector array technology that has at least one active transistor within the pixel unit cell. The APS eliminates the need for nearly perfect charge transfer -- the Achilles' heel of CCDs. This perfect charge transfer makes CCD's radiation 'soft,' difficult to use under low light conditions, difficult to manufacture in large array sizes, difficult to integrate with on-chip electronics, difficult to use at low temperatures, difficult to use at high frame rates, and difficult to manufacture in non-silicon materials that extend wavelength response.

  5. Spectral response of a silicon detector with 220 {mu}m pixel size bonded to MEDIPIX2

    Energy Technology Data Exchange (ETDEWEB)

    Froejdh, Erik, E-mail: erik.frojdh@miun.se [Department of Information Technology and Media, Mid-Sweden University, SE-85170 Sundsvall (Sweden); Froejdh, Anna; Norlin, Boerje; Froejdh, Christer [Department of Information Technology and Media, Mid-Sweden University, SE-85170 Sundsvall (Sweden)

    2011-05-15

    Pixellated radiation detectors with single photon processing can be used for spectral X-ray imaging. A problem using such detectors with small pixels is that the spectral information is distorted by charge sharing. In order to get images with good spectral resolution a number of silicon sensors with a pixel size of 220 {mu}m were fabricated and bonded to a MEDIPIX2 readout chip using only a limited number of pixels on the readout chip. The device was then used in an X-ray microscopy setup to obtain good spatial resolution as well. It is shown that spectral imaging can provide good contrast images of embedded structures by selecting an appropriate energy window.

  6. MTF Issues in Small-Pixel-Pitch Planar Quantum IR Detectors

    Science.gov (United States)

    Gravrand, O.; Baier, N.; Ferron, A.; Rochette, F.; Berthoz, J.; Rubaldo, L.; Cluzel, R.

    2014-08-01

    The current trend in quantum infrared (IR) detector development is the design of very small-pixel-pitch large arrays. From the previous 30 μm pitch, the standard pixel pitch today is 15 μm and is expected to decrease to 12 μm in the next few years. Furthermore, focal-plane arrays (FPAs) with pixel pitch as small as 10 μm have been demonstrated. Such ultrasmall-pixel pitches are very small compared with the typical length ruling the electrical characteristics of the absorbing materials, namely the minority-carrier diffusion length. As an example, for low-doped n-type HgCdTe or InSb material, this diffusion length is on the order of 30 μm to 50 μm, i.e., three to five times the targeted pixel pitches. This has strong consequences for the modulation transfer function (MTF) of planar structures, where the lateral extension of the photodiode is limited by diffusion. For such aspect ratios, the self-confinement of neighboring diodes may not be efficient enough to maintain an optimal MTF. Therefore, this issue has to be addressed to take full advantage of the pixel pitch reduction in terms of image resolution. The aim of this work is to investigate the evolution of the MTF of HgCdTe and InSb FPAs when decreasing the pixel pitch below 15 μm. Both experimental measurements and finite-element simulations are used to discuss this issue. Different scenarios are compared, namely deep mesa etch between pixels, internal drift, surface recombination, and thin absorbing layers.

  7. Resolution studies with the DATURA beam telescope

    CERN Document Server

    Jansen, Hendrik

    2016-01-01

    We present resolution studies carried out with the DATURA beam telescope, which belongs to the family of EUDET-type beam telescopes. The EUDET-type beam telescopes make use of CMOS MIMOSA 26 pixel detectors for particle tracking allowing for precise characterisation of particle sensing devices. A profound understanding of the performance of the beam telescope as a whole is obtained by a detailed characterisation of the sensors themselves. We extract the differential intrinsic resolution as measured in a MIMOSA 26 sensor using an iterative pull method and show various clustersize dependent quantities as the residual distribution, the intra-pixel residual width distribution and the intra-pixel frequency distribution.

  8. Physics performance of the ATLAS pixel detector

    Science.gov (United States)

    Tsuno, S.

    2017-01-01

    In preparation for LHC Run-2 the ATLAS detector introduced a new pixel detector, the Insertable B-Layer (IBL). This detector is located between the beampipe and what was the innermost pixel layer. The tracking and vertex reconstruction are significantly improved and good performance is expected in high level objects such a b-quark jet tagging. This in turn, leads to better physics results. This note summarizes the impact of the IBL detector on physics results, especially focusing on the analyses using b-quark jets throughout 2016 summer physics program.

  9. Commissioning of the ATLAS pixel detector

    Energy Technology Data Exchange (ETDEWEB)

    ATLAS Collaboration; Golling, Tobias

    2008-09-01

    The ATLAS pixel detector is a high precision silicon tracking device located closest to the LHC interaction point. It belongs to the first generation of its kind in a hadron collider experiment. It will provide crucial pattern recognition information and will largely determine the ability of ATLAS to precisely track particle trajectories and find secondary vertices. It was the last detector to be installed in ATLAS in June 2007, has been fully connected and tested in-situ during spring and summer 2008, and is ready for the imminent LHC turn-on. The highlights of the past and future commissioning activities of the ATLAS pixel system are presented.

  10. Physics performance of the ATLAS Pixel Detector

    CERN Document Server

    Tsuno, Soshi; The ATLAS collaboration

    2016-01-01

    One noticeable upgrade from Run-1 to Run-2 with ATLAS detector in proton-proton collisions at LHC is the introduction of the new pixel detector, IBL, located on the beam pipe as the extra innermost pixel layer. The tracking and vertex reconstruction are significantly improved and good performance is expected in high level object such a $b$-quark jet tagging, in turn, it leads the better physics results. This note summarizes what is the impact on the IBL detector to the physics results especially focusing on the analyses using the $b$-quark jets throughout 2016 summer physics program.

  11. Monte Carlo Optimization of Crystal Configuration for Pixelated Molecular SPECT Scanners

    Science.gov (United States)

    Mahani, Hojjat; Raisali, Gholamreza; Kamali-Asl, Alireza; Ay, Mohammad Reza

    2017-02-01

    Resolution-sensitivity-PDA tradeoff is the most challenging problem in design and optimization of pixelated preclinical SPECT scanners. In this work, we addressed such a challenge from a crystal point-of-view by looking for an optimal pixelated scintillator using GATE Monte Carlo simulation. Various crystal configurations have been investigated and the influence of different pixel sizes, pixel gaps, and three scintillators on tomographic resolution, sensitivity, and PDA of the camera were evaluated. The crystal configuration was then optimized using two objective functions: the weighted-sum and the figure-of-merit methods. The CsI(Na) reveals the highest sensitivity of the order of 43.47 cps/MBq in comparison to the NaI(Tl) and the YAP(Ce), for a 1.5×1.5 mm2 pixel size and 0.1 mm gap. The results show that the spatial resolution, in terms of FWHM, improves from 3.38 to 2.21 mm while the sensitivity simultaneously deteriorates from 42.39 cps/MBq to 27.81 cps/MBq when pixel size varies from 2×2 mm2 to 0.5×0.5 mm2 for a 0.2 mm gap, respectively. The PDA worsens from 0.91 to 0.42 when pixel size decreases from 0.5×0.5 mm2 to 1×1 mm2 for a 0.2 mm gap at 15° incident-angle. The two objective functions agree that the 1.5×1.5 mm2 pixel size and 0.1 mm Epoxy gap CsI(Na) configuration provides the best compromise for small-animal imaging, using the HiReSPECT scanner. Our study highlights that crystal configuration can significantly affect the performance of the camera, and thereby Monte Carlo optimization of pixelated detectors is mandatory in order to achieve an optimal quality tomogram.

  12. CMS 2017 Pixel detector replacement - A roll and B roll

    CERN Multimedia

    Paola Catapano

    2017-01-01

    On Thursday 2 March 2017 CERN physicists and engineers have carried out a highly complex operation right at the heart of one of the four main experiments of the Large Hadron Collider (LHC): the CMS detector, located 100 m below ground under French territory, at one of the LHC’s collision points. CMS is one of the four main detectors on the 27km LHC accelerator., and one of the two experiments which found the Higgs boson in 2012. The heart of the CMS experiment is the pixel detector, the innermost instrument in the very heart of the CMS apparatus, the very point where new particles, such as the Higgs boson, are produced by the energy of the proton proton collisions of the LHC accelerator. With thousands of silicon sensors, the new Pixel Tracker is now being upgraded to improve the particle-tracking capabilities of CMS. This operation, started on Tuesday Feb 28 when the first components of the new instrument were descended into the experiment’s cavern, is one of the most significant milestones ahead of the ...

  13. arXiv The FoCal prototype - an extremely fine-grained electromagnetic calorimeter using CMOS pixel sensors

    CERN Document Server

    Nooren, G.; Peitzmann, T.; Reicher, M.; Rocco, E.; Roehrich, D.; Ullaland, K.; van den Brink, A.; van Leeuwen, M.; Wang, H.; Yang, S.; Zhang, C.

    A prototype of a Si-W EM calorimeter was built with Monolithic Active Pixel Sensors as the active elements. With a pixelsize of 30 $\\mu$m it allows digital calorimetry, i.e. the particles' energy is determined by counting pixels, not by measuring the energy deposited. Although of modest size, only 4 Moliere radii wide, it has 39 million pixels. We describe the construction and tuning of the prototype and present results from beam tests and compare them with predictions of GEANT-based Monte Carlo simulations. We show the shape of showers caused by electrons in unprecedented detail. Results for energy and position resolution will also be given.

  14. Combining structure-from-motion derived point clouds from satellites and unmanned aircraft systems images with ground-truth data to create high-resolution digital elevation models

    Science.gov (United States)

    Palaseanu, M.; Thatcher, C.; Danielson, J.; Gesch, D. B.; Poppenga, S.; Kottermair, M.; Jalandoni, A.; Carlson, E.

    2016-12-01

    Coastal topographic and bathymetric (topobathymetric) data with high spatial resolution (1-meter or better) and high vertical accuracy are needed to assess the vulnerability of Pacific Islands to climate change impacts, including sea level rise. According to the Intergovernmental Panel on Climate Change reports, low-lying atolls in the Pacific Ocean are extremely vulnerable to king tide events, storm surge, tsunamis, and sea-level rise. The lack of coastal topobathymetric data has been identified as a critical data gap for climate vulnerability and adaptation efforts in the Republic of the Marshall Islands (RMI). For Majuro Atoll, home to the largest city of RMI, the only elevation dataset currently available is the Shuttle Radar Topography Mission data which has a 30-meter spatial resolution and 16-meter vertical accuracy (expressed as linear error at 90%). To generate high-resolution digital elevation models (DEMs) in the RMI, elevation information and photographic imagery have been collected from field surveys using GNSS/total station and unmanned aerial vehicles for Structure-from-Motion (SfM) point cloud generation. Digital Globe WorldView II imagery was processed to create SfM point clouds to fill in gaps in the point cloud derived from the higher resolution UAS photos. The combined point cloud data is filtered and classified to bare-earth and georeferenced using the GNSS data acquired on roads and along survey transects perpendicular to the coast. A total station was used to collect elevation data under tree canopies where heavy vegetation cover blocked the view of GNSS satellites. A subset of the GPS / total station data was set aside for error assessment of the resulting DEM.

  15. Ground-glass opacity in diffuse lung diseases: high-resolution computed tomography-pathology correlation; Opacidades em vidro fosco nas doencas pulmonares difusas: correlacao da tomografia computadorizada de alta resolucao com a anatomopatologia

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Maria Lucia de Oliveira; Vianna, Alberto Domingues; Marchiori, Edson [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Dept. de Radiologia; Souza Junior, Arthur Soares [Faculdade de Medicina de Sao Jose do Rio Preto (FAMERP), SP (Brazil). Disciplina de Radiologia; Moraes, Heleno Pinto de [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Dept. de Patologia]. E-mail: edmarchiori@zipmail.com.br

    2003-12-01

    Ground-glass opacity is a finding frequently seen in high-resolution computed tomography examinations of the chest and is characterized by hazy increased attenuation of lung, however without blurring of bronchial and vascular margins. Due to its un specificity, association with other radiological, clinical and pathological findings must be considered for an accurate diagnostic interpretation. In this paper were reviewed 62 computed tomography examinations of patients with diffuse pulmonary diseases of 14 different etiologies in which ground-glass opacity was the only or the most remarkable finding, and correlated this findings with pathology abnormalities seen on specimens obtained from biopsies or necropsies. In pneumocystosis, ground-glass opacities correlated histologically with alveolar occupation by a foaming material containing parasites, in bronchiole alveolar cell carcinoma with thickening of the alveolar septa and occupation of the lumen by mucus and tumoral cells, in paracoccidioidomycosis with thickening of the alveolar septa, areas of fibrosis and alveolar bronchopneumonia exudate, in sarcoidosis with fibrosis or clustering of granulomas and in idiopathic pulmonary fibrosis with alveolar septa thickening due to fibrosis. Alveolar occupation by blood was found in cases of leptospirosis, idiopathic hemo siderosis, metastatic kidney tumor and invasive aspergillosis whereas oily vacuole were seen in lipoid pneumonia, proteinaceous and lipo proteinaceous material in silico proteinosis and pulmonary alveolar proteinosis, and edematous fluid in cardiac failure. (author)

  16. CMOS pixel sensors on high resistive substrate for high-rate, high-radiation environments

    Science.gov (United States)

    Hirono, Toko; Barbero, Marlon; Breugnon, Patrick; Godiot, Stephanie; Gonella, Laura; Hemperek, Tomasz; Hügging, Fabian; Krüger, Hans; Liu, Jian; Pangaud, Patrick; Peric, Ivan; Pohl, David-Leon; Rozanov, Alexandre; Rymaszewski, Piotr; Wang, Anqing; Wermes, Norbert

    2016-09-01

    A depleted CMOS active pixel sensor (DMAPS) has been developed on a substrate with high resistivity in a high voltage process. High radiation tolerance and high time resolution can be expected because of the charge collection by drift. A prototype of DMAPS was fabricated in a 150 nm process by LFoundry. Two variants of the pixel layout were tested, and the measured depletion depths of the variants are 166 μm and 80 μm. We report the results obtained with the prototype fabricated in this technology.

  17. MuPix7 - A fast monolithic HV-CMOS pixel chip for Mu3e

    CERN Document Server

    Augustin, H; Dittmeier, S; Hammerich, J; Hartenstein, U; Huang, Q; Huth, L; Immig, D; Kozlinskiy, A; Aeschbacher, F Meier; Perić, I; Perrevoort, A -K; Schöning, A; Shrestha, S; Sorokin, I; Tyukin, A; Bruch, D vom; Wauters, F; Wiedner, D; Zimmermann, M

    2016-01-01

    The MuPix7 chip is a monolithic HV-CMOS pixel chip, thinned down to 50 \\mu m. It provides continuous self-triggered, non-shuttered readout at rates up to 30 Mhits/chip of 3x3 mm^2 active area and a pixel size of 103x80 \\mu m^2. The hit efficiency depends on the chosen working point. Settings with a power consumption of 300 mW/cm^2 allow for a hit efficiency >99.5%. A time resolution of 14.2 ns (Gaussian sigma) is achieved. Latest results from 2016 test beam campaigns are shown.

  18. Commissioning and Performance of the CMS Pixel Tracker with Cosmic Ray Muons

    CERN Document Server

    INSPIRE-00165402; Abadjiev, K; Abbaneo, D; Abbiendi, G; Abbrescia, M; Abdullin, S; Abelev, B; Acosta, D; Acosta, J G; Actis, O; Adam, N; Adams, M R; Adams, T; Adam, W; Adiguzel, A; Adler, V; Adolphi, R; Adzic, P; Afaq, M A; Agostino, L; Agram, J L; Aguilar-Benitez, M; Ahmad, M; Ahmed, I; Ahmed, W; Ahuja, S; Aisa, D; Aisa, S; Akchurin, N; Akgun, B; Akgun, U; Akimenko, S; Akin, I V; Alagoz, E; Alampi, G; Albajar, C; Albayrak, E A; Alberdi, J; Albergo, S; Albert, E; Albrow, M; Alcaraz Maestre, J; Aldaya Martin, M; Alexander, J; Alidra, M; Aliev, T; Allfrey, P; Almeida, N; Altenhöfer, G; Altsybeev, I; Alver, B; Alverson, G; Alves, G A; Amaglobeli, N; Amapane, N; Ambroglini, F; Amsler, C; Anagnostou, G; Ananthan, B; Anastassov, A; Andelin, D; Anderson, M; Andrea, J; Andreev, V; Andreev, Yu; Anghel, I M; Anguelov, T; Anisimov, A; Antillon, E; Antipov, P; Antonelli, L; Anttila, E; Antunes Pedro, L; Antunovic, Z; Apanasevich, L; Apollinari, G; Apresyan, A; Arce, P; Arcidiacono, R; Arenton, M W; Arfaei, H; Argiro, S; Arisaka, K; Arneodo, M; Arnold, B; Arora, S; Artamonov, A; Asaadi, J; Asghar, M I; Ashby, S; Askew, A; Atac, M; Atramentov, O; Auffray, E; Aurisano, A; Autermann, C; Avery, P; Avetisyan, A; Avila, C; Awan, M I M; Ayan, A S; Ayhan, A; Azhgirey, I; Aziz, T; Azman Gokce, A; Azzi, P; Azzurri, P; Baarmand, M M; Babb, J; Babucci, E; Baccaro, S; Bacchetta, N; Bacchi, W; Bachtis, M; Baden, D; Badgett, W; Baechler, J; Baer, H; Baesso, P; Baffioni, S; Bagby, L; Bagliesi, G; Bahk, S Y; Bailleux, D; Baillon, P; Bainbridge, R; Bakhshiansohi, H; Bakirci, M N; Bakken, J A; Balazs, M; Baldin, B; Ball, A H; Ball, G; Ballin, J; Bally, S L; Bandurin, D; Banerjee, S; Banerjee, S; Banicz, K; Bansal, S; Ban, Y; Banzuzi, K; Baquero Ruiz, M; Barashko, V; Barbagli, G; Barberis, E; Barbone, L; Barcala, J M; Barcellan, L; Bard, R; Bargassa, P; Baringer, P; Barnes, V E; Barnett, B A; Barney, D; Barone, L; Bartalini, P; Bartoloni, A; Bartz, E; Basegmez, S; Battilana, C; Baty, C; Baud, A; Bauerdick, L A T; Bauer, G; Bauer, J; Baur, U; Bawa, H S; Bazterra, V E; Bean, A; Beauceron, S; Beaudette, F; Beaumont, W; Bechtel, F; Bedjidian, M; Beetz, C P; Behrens, U; Belforte, S; Beliy, N; Bellan, P; Bellan, R; Bellato, M; Bellinger, J N; Bell, K W; Belotelov, I; Benaglia, A; Bencze, G; Bendavid, J; Bender, W; Benedetti, D; Benelli, G; Benettoni, M; Beni, N; Benucci, L; Benussi, L; Benvenuti, A C; Beretvas, A; Bergauer, H; Bergauer, T; Beri, S B; Bernardini, J; Bernardino Rodrigues, N; Bernet, C; Berntzon, L; Berretta, L; Berry, D; Berry, E; Berryhill, J; Bertani, M; Bertl, W; Bertoldi, M; Berzano, U; Besancon, M; Besson, A; Betchart, B; Betev, B; Betts, R R; Beuselinck, R; Bhatnagar, V; Bhat, P C; Bhattacharya, S; Bhattacharya, S; Bhatti, A; Biallass, P; Bianchini, L; Bianco, S; Biasini, M; Biasotto, M; Biery, K; Biino, C; Bilei, G M; Bilki, B; Bilmis, S; Binkley, M; Bisello, D; Bitioukov, S; Blaha, J; Blanco Otano, M; Blekman, F; Bloch, D; Bloch, I; Bloch, P; Bloom, K; Bluj, M; Blumenfeld, B; Blüm, P; Blyweert, S; Boccali, T; Bocci, A; Bockelman, B; Bodek, A; Bodin, D; Boeriu, O; Boldini, M; Boldizsar, L; Bolla, G; Bolognesi, S; Bolton, T; Bonacorsi, D; Bona, M; Bonato, A; Bondar, N; Bonnett Del Alamo, M; Bontenackels, M; Boos, E; Borcherding, F; Borgia, M A; Bornheim, A; Borras, K; Borrello, L; Borsato, E; Bortoletto, D; Bose, M; Bose, S; Bose, T; Bosi, F; Bos, J; Bostock, F; Botta, C; Boudoul, G; Bouhali, O; Bourgeois, N; Bourilkov, D; Bourrel, T; Boutemeur, M; Boutle, S; Braibant-Giacomelli, S; Branca, A; Branson, J G; Brauer, R; Braunschweig, W; Breedon, R; Brett, A M; Breuker, H; Brew, C; Bricola, S; Briggs, R; Brigljevic, V; Broccolo, G; Brom, J M; Brooke, J J; Brown, R M; Brun, H; Bruno, G; Buchmuller, O; Budd, H; Buege, V; Buehler, M; Bunin, P; Bunkowski, K; Bunn, J; Buontempo, S; Burgos Lazaro, C; Burkett, K; Burtovoy, V; Busson, P; Busza, W; Butler, J N; Butler, P H; Butt, J; Butz, E; Bylsma, B; Caballero Bejar, J; Cabrillo, I J; Cafaro, V D; Caiazza, S S; Cai, J; Cakir, A; Calderon, A; Calderon De La Barca Sanchez, M; Cali, I A; Callner, J; Calloni, M; Calvo, E; Calzolari, F; Camanzi, B; Caminada, L; Campagnari, C; Campbell, A; Campi, D; Camporesi, T; Cankocak, K; Cano, E; Capiluppi, P; Caponeri, B; Cardaci, M; Cardenas Montes, M; Carleton, M; Carlin, R; Carlsmith, D; Carrillo Montoya, C A; Carrillo Moreno, S; Carroll, R; Cartiglia, N; Carvalho, W; Case, M; Cassel, D; Castaldi, R; Castellani, L; Castello, R; Castilla Valdez, H; Castro, A; Castro, E; Castro, M A; Cattai, A; Caudron, J; Cavallari, F; Cavallo, F R; Cavallo, N; Cavanaugh, R; Cebra, D; Cepeda, M; Cerati, G B; Cerci, S; Cerizza, G; Cerminara, G; Ceron, C; Cerrada, M; Chabert, E C; Chamizo Llatas, M; Chandra, A; Chang, P; Chang, S; Chang, Y H; Chan, M; Chanon, N; Chao, Y; Charaf, O; Charlot, C; Chatelain, J P; Chatterjee, A; Chauhan, S; Chauvey, M; Checchia, P; Checcucci, B; Chekhovsky, V; Chen, E A; Chen, G M; Cheng, T L; Chen, H S; Chen, J; Chen, K F; Chen, M; Chen, W T; Chen, Z; Chertok, M; Chetluru, V; Cheung, H W K; Chien, C Y; Chierici, R; Chiochia, V; Chiorboli, M; Chipaux, R; Chiumarulo, F; Chlebana, F; Choi, M; Choi, S; Choi, Y; Choudhary, B C; Choudhury, R K; Chou, J P; Christian, G; Christiansen, T; Chtchipounov, L; Chuang, S H; Chung, J; Chung, K; Chung, Y S; Churin, I; Chwalek, T; Cihangir, S; Cimmino, A; Cirino, G; Cittolin, S; Ciulli, V; Civinini, C; Claes, D R; Clare, R; Clarida, W; Clemente, A; Clemente, F; Clerbaux, B; Cline, D; Coarasa Perez, J A; Cockerill, D J A; Codispoti, G; Colafranceschi, S; Colaleo, A; Cole, J E; Colino, N; Colling, D; Colonna, D; Conde Garcia, A; Conetti, S; Contardo, D; Conte, E; Conti, E; Conway, J; Cooper, S I; Cossutti, F; Costa, M; Costa, S; Coughlan, J A; Cousins, R; Covarelli, R; Cox, B; Cox, P T; Crawford, M; Creanza, D; Cremaldi, L M; Cripps, N; Crotty, I; Cuevas, J; Cuffiani, M; Cumalat, J P; Cuplov, V; Curé, B; Cuscela, G; Cushman, P; Cussans, D; Cutts, D; Cwiok, M; Czellar, S; Dabrowski, R; Dafinei, I; Dagenhart, W; Dahmes, B; Dal Corso, F; D'Alessandro, R; D'Alfonso, M; Dallavalle, G M; Dambach, S; Damgov, J; Dammann, D; D'Angelo, P; Daniel, M; Danielson, T; D'Antone, I; Darmenov, N; Da Silva Di Calafiori, D R; Daskalakis, G; Das, S; Dasu, S; Dattola, D; Daubie, E; David, A; Davids, M; Davies, G; de Barbaro, P; Debbins, P; De Benedetti, A; De Boer, W; Debreczeni, G; De Filippis, N; De Gruttola, M; De Guio, F; Deiters, K; Dejardin, M; De Jesus Damiao, D; Delachenal, V; De La Cruz, B; Delaere, C; De Lentdecker, G; Delgado Peris, A; Deliomeroglu, M; Dellacasa, G; Della Negra, M; Della Ricca, G; Dell'Orso, R; Delmeire, E; Del Re, D; Demaria, N; Demarteau, M; De Mattia, M; Demina, R; Demin, P; Demir, D; Demortier, L; Denegri, D; Denisov, A; Deniz, M; D'Enterria, D; De Oliveira Martins, C; De Palma, M; Depasse, P; Dermenev, A; De Robertis, G; De Roeck, A; Dero, V; Derylo, G; Descamps, J; de Trocóniz, J F; De Visscher, S; Devroede, O; De Weirdt, S; De Wolf, E A; Deyrail, D; Dharmaratna, W G D; D'Hondt, J; Diaz Merino, I; Diemoz, M; Dierlamm, A; Diez Gonzalez, C; Diez Pardos, C; Di Giovanni, G P; Di Marco, E; Dimitrov, A; Dimitrov, L; Dinardo, M E; Dinu, N; Dirkes, G; Dissertori, G; Dittmar, M; Di Vincenzo, S; Djaoshvili, N; Djordjevic, M; Dobrzynski, L; Dobur, D; Dolen, J; Dolgopolov, A; Dominguez, A; Dominik, W; Donvito, G; Dorigo, T; Doroba, K; Dos Santos, S; Dosselli, U; Draeger, J; Dragicevic, M; Dragoiu, C; Drell, B R; Dremin, I; Drouhin, F; Drozdetskiy, A; Druzhkin, D; Duarte Campderros, J; Dubinin, M; Duda, M; Dudero, P R; Dudko, L; Dugad, S; Dughera, G; Dumanoglu, I; Dumitrache, F; Dupasquier, T; Dupont, T; Duric, S; Durkin, L S; Duru, F; Dusinberre, E; Dutta, D; Dutta, S; Dvornikov, O; Dykstra, D; Dyulendarova, M; Dzelalija, M; Eads, M; Eartly, D P; Eckerlin, G; Ecklund, K M; Eckstein, D; Edelhoff, M; Edera, L M; Efron, J; Egeland, R; Eggel, C; Eichberger, M; Elgammal, S; Elias, J E; Elliott-Peisert, A; Ellison, J A; El Mamouni, H; Elmer, P; Elvira, V D; Emeliantchik, I; Engh, D; Eno, S C; Eppard, M; Epshteyn, V; Erbacher, R; Erdmann, M; Erdmann, W; Erhan, S; Erö, J; Ershov, A; Ershov, Y; Esen, S; Eskut, E; Esser, H; Eugster, J; Eulisse, G; Eusebi, R; Evangelou, I; Evans, D; Evans, D; Everaerts, P; Everett, A; Fabbricatore, P; Fabbri, F; Fabbri, F; Fabbro, B; Faber, G; Fabozzi, F; Faccioli, P; Fahim, A; Fanfani, A; Fanò, L; Fanzago, F; Farina, F M; Farnesini, L; Fasanella, D; Fassi, F; Faure, J L; Favart, D; Favre, M; Fay, J; Fedele, F; Fedorov, A; Fehling, D; Feindt, M; Felcini, M; Feld, L; Felzmann, U; Feng, L; Ferencek, D; Fereos, R; Ferguson, T; Fernandez Bedoya, C; Fernandez Menendez, J; Fernandez, M; Fernandez Perez Tomei, T R; Fernández Ramos, J P; Ferrando, A; Ferreira Dias, M A; Ferreira Parracho, P G; Ferri, F; Fetchenhauer, G; Feyzi, F; Field, R D; Filozova, I; Finger, M.; Finger Jr., M.; Fiore, L; Fiori, F; Fischler, M; Fisk, I; Flacher, H; Flix, J; Flood, K; Florez, C; Flossdorf, A; Flucke, G; Flügge, G; Foà, L; Focardi, E; Fonseca De Souza, S; Fontaine, J C; Ford, W T; Foudas, C; Foulkes, S; Fouz, M C; Franci, D; Franco, M; Frangenheim, J; Frank, N; Franzoni, G; Frazier, R; Freeman, J; Freitas Ferreira, M; Freudenreich, K; Frey, M; Friedl, M; Friis, E; Frosali, S; Frueboes, T; Frühwirth, R; Fulcher, J; Funk, W; Furgeri, A; Furic, I K; Futyan, D; Fu, Y; Gabathuler, K; Gaddi, A; Galanti, M; Gallinaro, M; Gallo, E; Gamsizkan, H; Ganjour, S; Garberson, J; Garcia-Abia, P; Garcia-Bonilla, A C; Garcia Raboso, A; Garcia-Solis, E J; Garfinkel, A F; Garmash, A; Gartner, J; Gartung, P; Gary, J W; Gascon, S; Gasparini, F; Gasparini, U; Gastal, M; Gataullin, M; Gateau, M; Gaultney, V; Gavrikov, Y; Gavrilov, G; Gavrilov, V; Gay, A P R; Gebbert, U; Gecse, Z; Geddes, N I; Geenen, H; Geiser, A; Gelé, D; Genchev, V; Gennai, S; Genta, C; Gentit, F X; Geralis, T; Gerbaudo, D; Gerber, C E; Gershtein, Y; Gerwig, H; Geurts, F J M; Ge, Y; Ghete, V M; Ghezzi, A; Giacomelli, P; Giammanco, A; Giardoni, M; Giassi, A; Gibbons, L K; Giffels, M; Gigi, D; Gill, K; Gilmore, J; Giordano, D; 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    2010-01-01

    The pixel detector of the Compact Muon Solenoid experiment consists of three barrel layers and two disks for each endcap. The detector was installed in summer 2008, commissioned with charge injections, and operated in the 3.8 T magnetic field during cosmic ray data taking. This paper reports on the first running experience and presents results on the pixel tracker performance, which are found to be in line with the design specifications of this detector. The transverse impact parameter resolution measured in a sample of high momentum muons is 18 microns.

  19. CMOS pixel sensors on high resistive substrate for high-rate, high-radiation environments

    Energy Technology Data Exchange (ETDEWEB)

    Hirono, Toko, E-mail: thirono@uni-bonn.de [Physikalisches Institute der Universität Bonn, Bonn (Germany); Barbero, Marlon; Breugnon, Patrick; Godiot, Stephanie [CPPM, Aix-Marseille Universite, CNRS/IN2P3, Marseille (France); Gonella, Laura; Hemperek, Tomasz; Hügging, Fabian; Krüger, Hans [Physikalisches Institute der Universität Bonn, Bonn (Germany); Liu, Jian; Pangaud, Patrick [CPPM, Aix-Marseille Universite, CNRS/IN2P3, Marseille (France); Peric, Ivan [IPE, Karlsruher Institut für Technologie, Karlsruhe (Germany); Pohl, David-Leon [Physikalisches Institute der Universität Bonn, Bonn (Germany); Rozanov, Alexandre [CPPM, Aix-Marseille Universite, CNRS/IN2P3, Marseille (France); Rymaszewski, Piotr [Physikalisches Institute der Universität Bonn, Bonn (Germany); Wang, Anqing [CPPM, Aix-Marseille Universite, CNRS/IN2P3, Marseille (France); Wermes, Norbert [Physikalisches Institute der Universität Bonn, Bonn (Germany)

    2016-09-21

    A depleted CMOS active pixel sensor (DMAPS) has been developed on a substrate with high resistivity in a high voltage process. High radiation tolerance and high time resolution can be expected because of the charge collection by drift. A prototype of DMAPS was fabricated in a 150 nm process by LFoundry. Two variants of the pixel layout were tested, and the measured depletion depths of the variants are 166 μm and 80 μm. We report the results obtained with the prototype fabricated in this technology.

  20. Gamma spectroscopic measurements using the PID350 pixelated CdTe radiation detector

    CERN Document Server

    Karafasoulis, K; Seferlis, S; Papadakis, I; Loukas, D; Lambropoulos, C; Potiriadis, C

    2010-01-01

    Spectroscopic measurements are presented using the PID350 pixelated gamma radiation detectors. A high-speed data acquisition system has been developed in order to reduce the data loss during the data reading in case of a high flux of photons. A data analysis framework has been developed in order to improve the resolution of the acquired energy spectra, using specific calibration parameters for each PID350's pixel. Three PID350 detectors have been used to construct a stacked prototype system and spectroscopic measurements have been performed in order to test the ability of the prototype to localize radioactive sources.

  1. Commissioning and Performance of the CMS Pixel Tracker with Cosmic Ray Muons

    CERN Document Server

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Wright, D; Wrochna, G; Wulz, C E; Würthwein, F; Wu, S; Wu, W; Wyslouch, B; Xie, S; Xie, Z; Xue, Z; Yagil, A; Yang, X; Yang, Y; Yang, Z C; Yan, M; Yarba, J; Yaselli, I; Yazgan, E; Yelton, J; Yetkin, T; Yi, K; Yilmaz, Y; Yohay, R; Yoo, H D; Yoon, A S; York, A; Yumiceva, F; Yun, J C; Yuste, C; Zabi, A; Zabolotny, W; Zachariadou, A; Zalewski, P; Zampieri, A; Zanetti, M; Zang, S L; Zarubin, A; Zatzerklyany, A; Zeidler, C; Zeinali, M; Zeise, M; Zelepoukine, S; Zeuner, W D; Zeyrek, M; Zhang, J; Zhang, L; Zhang, Y; Zhang, Z; Zheng, Y; Zhiltsov, V; Zhokin, A; Zhu, B; Zhukova, V; Zhukov, V; Zhu, K; Zhu, R Y; Ziebarth, E B; Zielinski, M; Zilizi, G; Zinonos, Z; Zito, G; Zoeller, M H; Zotto, P; Zub, S; Zumerle, G; Zuranski, A; Zuyeuski, R; Zych, P

    2010-01-01

    The pixel detector of the Compact Muon Solenoid experiment consists of three barrel layers and two disks for each endcap. The detector was installed in summer 2008, commissioned with charge injections, and operated in the 3.8 T magnetic field during cosmic ray data taking. This paper reports on the first running experience and presents results on the pixel tracker performance, which are found to be in line with the design specifications of this detector. The transverse impact parameter resolution measured in a sample of high momentum muons is 18 microns.

  2. A Wideband Circularly Polarized Pixelated Dielectric Resonator Antenna

    Science.gov (United States)

    Trinh-Van, Son; Yang, Youngoo; Lee, Kang-Yoon; Hwang, Keum Cheol

    2016-01-01

    The design of a wideband circularly polarized pixelated dielectric resonator antenna using a real-coded genetic algorithm (GA) is presented for far-field wireless power transfer applications. The antenna consists of a dielectric resonator (DR) which is discretized into 8 × 8 grid DR bars. The real-coded GA is utilized to estimate the optimal heights of the 64 DR bars to realize circular polarization. The proposed antenna is excited by a narrow rectangular slot etched on the ground plane. A prototype of the proposed antenna is fabricated and tested. The measured −10 dB reflection and 3 dB axial ratio bandwidths are 32.32% (2.62–3.63 GHz) and 14.63% (2.85–3.30 GHz), respectively. A measured peak gain of 6.13 dBic is achieved at 3.2 GHz. PMID:27563897

  3. A Wideband Circularly Polarized Pixelated Dielectric Resonator Antenna.

    Science.gov (United States)

    Trinh-Van, Son; Yang, Youngoo; Lee, Kang-Yoon; Hwang, Keum Cheol

    2016-08-23

    The design of a wideband circularly polarized pixelated dielectric resonator antenna using a real-coded genetic algorithm (GA) is presented for far-field wireless power transfer applications. The antenna consists of a dielectric resonator (DR) which is discretized into 8 × 8 grid DR bars. The real-coded GA is utilized to estimate the optimal heights of the 64 DR bars to realize circular polarization. The proposed antenna is excited by a narrow rectangular slot etched on the ground plane. A prototype of the proposed antenna is fabricated and tested. The measured -10 dB reflection and 3 dB axial ratio bandwidths are 32.32% (2.62-3.63 GHz) and 14.63% (2.85-3.30 GHz), respectively. A measured peak gain of 6.13 dBic is achieved at 3.2 GHz.

  4. Volume Based DTM Generation from Very High Resolution Photogrammetric Dsms

    Science.gov (United States)

    Piltz, B.; Bayer, S.; Poznanska, A. M.

    2016-06-01

    In this paper we propose a new algorithm for digital terrain (DTM) model reconstruction from very high spatial resolution digital surface models (DSMs). It represents a combination of multi-directional filtering with a new metric which we call normalized volume above ground to create an above-ground mask containing buildings and elevated vegetation. This mask can be used to interpolate a ground-only DTM. The presented algorithm works fully automatically, requiring only the processing parameters minimum height and maximum width in metric units. Since slope and breaklines are not decisive criteria, low and smooth and even very extensive flat objects are recognized and masked. The algorithm was developed with the goal to generate the normalized DSM for automatic 3D building reconstruction and works reliably also in environments with distinct hillsides or terrace-shaped terrain where conventional methods would fail. A quantitative comparison with the ISPRS data sets Potsdam and Vaihingen show that 98-99% of all building data points are identified and can be removed, while enough ground data points (~66%) are kept to be able to reconstruct the ground surface. Additionally, we discuss the concept of size dependent height thresholds and present an efficient scheme for pyramidal processing of data sets reducing time complexity to linear to the number of pixels, O(WH).

  5. From Hybrid to CMOS Pixels ... a possibility for LHC's pixel future?

    CERN Document Server

    Wermes, Norbert

    2015-01-01

    Hybrid pixel detectors have been invented for the LHC to make tracking and vertexing possible at all in LHC's radiation intense environment. The LHC pixel detectors have meanwhile very successfully fulfilled their promises and R\\&D for the planned HL-LHC upgrade is in full swing, targeting even higher ionising doses and non-ionising fluences. In terms of rate and radiation tolerance hybrid pixels are unrivaled. But they have disadvantages as well, most notably material thickness, production complexity, and cost. Meanwhile also active pixel sensors (DEPFET, MAPS) have become real pixel detectors but they would by far not stand the rates and radiation faced from HL-LHC. New MAPS developments, so-called DMAPS (depleted MAPS) which are full CMOS-pixel structures with charge collection in a depleted region have come in the R\\&D focus for pixels at high rate/radiation levels. This goal can perhaps be realised exploiting HV technologies, high ohmic substrates and/or SOI based technologies. The paper covers t...

  6. Analysis of pixel systematics and space point reconstruction with DEPFET PXD5 matrices using high energy beam test data

    Energy Technology Data Exchange (ETDEWEB)

    Reuen, Lars

    2011-02-15

    To answer the current questions in particle physics vertex-detectors, the innermost sub-detector system of a multipurpose particle detector, with brilliant spatial resolution and at the same time with as little sensor material as possible are mandatory. These requirements are the driving force behind the newest generation of silicon pixel sensors like the DEPFET pixel, which incorporates the first amplification stage in form of a transistor in the fully depleted sensor bulk, allowing for a high spatial resolution even with thinned down sensors. A DEPFET pixel prototype system, build for the future TeV-scale liner collider ILC, was characterized in a high energy beam test at CERN with a spatial resolution and statistics that allowed for the first time in-pixel homogeneity measurements of DEPFET pixels. Yet, in the quest for higher precision the sensor development must be accompanied by progress in position reconstruction algorithms. A study with three novel approaches in position reconstruction was undertaken. The results of the in-pixel beam test and the performance of the new methods with an emphasis on {delta}-electrons will be presented here. (orig.)

  7. Fine-resolution repeat topographic surveying of dryland landscapes using UAS-based structure-from-motion photogrammetry: Assessing accuracy and precision against traditional ground-based erosion measurements

    Science.gov (United States)

    Gillian, Jeffrey K.; Karl, Jason W.; Elaksher, Ahmed; Duniway, Michael C.

    2017-01-01

    Structure-from-motion (SfM) photogrammetry from unmanned aerial system (UAS) imagery is an emerging tool for repeat topographic surveying of dryland erosion. These methods are particularly appealing due to the ability to cover large landscapes compared to field methods and at reduced costs and finer spatial resolution compared to airborne laser scanning. Accuracy and precision of high-resolution digital terrain models (DTMs) derived from UAS imagery have been explored in many studies, typically by comparing image coordinates to surveyed check points or LiDAR datasets. In addition to traditional check points, this study compared 5 cm resolution DTMs derived from fixed-wing UAS imagery with a traditional ground-based method of measuring soil surface change called erosion bridges. We assessed accuracy by comparing the elevation values between DTMs and erosion bridges along thirty topographic transects each 6.1 m long. Comparisons occurred at two points in time (June 2014, February 2015) which enabled us to assess vertical accuracy with 3314 data points and vertical precision (i.e., repeatability) with 1657 data points. We found strong vertical agreement (accuracy) between the methods (RMSE 2.9 and 3.2 cm in June 2014 and February 2015, respectively) and high vertical precision for the DTMs (RMSE 2.8 cm). Our results from comparing SfM-generated DTMs to check points, and strong agreement with erosion bridge measurements suggests repeat UAS imagery and SfM processing could replace erosion bridges for a more synoptic landscape assessment of shifting soil surfaces for some studies. However, while collecting the UAS imagery and generating the SfM DTMs for this study was faster than collecting erosion bridge measurements, technical challenges related to the need for ground control networks and image processing requirements must be addressed before this technique could be applied effectively to large landscapes.

  8. 2D Sub-Pixel Disparity Measurement Using QPEC / Medicis

    Science.gov (United States)

    Cournet, M.; Giros, A.; Dumas, L.; Delvit, J. M.; Greslou, D.; Languille, F.; Blanchet, G.; May, S.; Michel, J.

    2016-06-01

    In the frame of its earth observation missions, CNES created a library called QPEC, and one of its launcher called Medicis. QPEC / Medicis is a sub-pixel two-dimensional stereo matching algorithm that works on an image pair. This tool is a block matching algorithm, which means that it is based on a local method. Moreover it does not regularize the results found. It proposes several matching costs, such as the Zero mean Normalised Cross-Correlation or statistical measures (the Mutual Information being one of them), and different match validation flags. QPEC / Medicis is able to compute a two-dimensional dense disparity map with a subpixel precision. Hence, it is more versatile than disparity estimation methods found in computer vision literature, which often assume an epipolar geometry. CNES uses Medicis, among other applications, during the in-orbit image quality commissioning of earth observation satellites. For instance the Pléiades-HR 1A & 1B and the Sentinel-2 geometric calibrations are based on this block matching algorithm. Over the years, it has become a common tool in ground segments for in-flight monitoring purposes. For these two kinds of applications, the two-dimensional search and the local sub-pixel measure without regularization can be essential. This tool is also used to generate automatic digital elevation models, for which it was not initially dedicated. This paper deals with the QPEC / Medicis algorithm. It also presents some of its CNES applications (in-orbit commissioning, in flight monitoring or digital elevation model generation). Medicis software is distributed outside the CNES as well. This paper finally describes some of these external applications using Medicis, such as ground displacement measurement, or intra-oral scanner in the dental domain.

  9. Planar pixel sensors in commercial CMOS technologies

    Energy Technology Data Exchange (ETDEWEB)

    Gonella, Laura; Hemperek, Tomasz; Huegging, Fabian; Krueger, Hans; Wermes, Norbert [Physikalisches Institut der Universitaet Bonn, Nussallee 12, 53115 Bonn (Germany); Macchiolo, Anna [Max-Planck-Institut fuer Physik, Foehringer Ring 6, 80805 Muenchen (Germany)

    2015-07-01

    For the upgrade of the ATLAS experiment at the high luminosity LHC, an all-silicon tracker is foreseen to cope with the increased rate and radiation levels. Pixel and strip detectors will have to cover an area of up to 200m2. To produce modules in high number at reduced costs, new sensor and bonding technologies have to be investigated. Commercial CMOS technologies on high resistive substrates can provide significant advantages in this direction. They offer cost effective, large volume sensor production. In addition to this, production is done on 8'' wafers allowing wafer-to-wafer bonding to the electronics, an interconnection technology substantially cheaper than the bump bonding process used for hybrid pixel detectors at the LHC. Both active and passive n-in-p pixel sensor prototypes have been submitted in a 150 nm CMOS technology on a 2kΩ cm substrate. The passive sensor design will be used to characterize sensor properties and to investigate wafer-to-wafer bonding technologies. This first prototype is made of a matrix of 36 x 16 pixels of size compatible with the FE-I4 readout chip (i.e. 50 μm x 250 μm). Results from lab characterization of this first submission are shown together with TCAD simulations. Work towards a full size FE-I4 sensor for wafer-to-wafer bonding is discussed.

  10. What's A Pixel Particle Sensor Chip?

    CERN Multimedia

    2008-01-01

    ATLAS particle physics experiment aided with collaboration ON Semiconductor was recently honored by the European Council for Nuclear Research (CERN), with an Industrial Award recognizing the company's contribution in supplying complex "Pixel Particle Sensor" chips for use in CERN's ATLAS particle physics experiment.

  11. CMS has a heart of pixels

    CERN Multimedia

    2003-01-01

    At the core of CMS, particles will come into contact with tiny detector components, known as pixels, which are almost invisible to the naked eye. With these elementary cells measuring a mere 150 microns (or about 1/10 of a millimetre) along each side, a real technological leap has been made.

  12. ATLAS Pixel Group - Photo Gallery from Irradiation

    CERN Multimedia

    2001-01-01

    Photos 1,2,3,4,5,6,7 - Photos taken before irradiation of Pixel Test Analog Chip and Pmbars (April 2000) Photos 8,9,10,11 - Irradiation of VDC chips (May 2000) Photos 12, 13 - Irradiation of Passive Components (June 2000) Photos 14,15, 16 - Irradiation of Marebo Chip (November 1999)

  13. Performance of active edge pixel sensors

    CERN Document Server

    Bomben, Marco; Bagolini, Alvise; Boscardin, Maurizio; Bosisio, Luciano; Calderini, Giovanni; D'Eramo, Louis; Giacomini, Gabriele; Marchiori, Giovanni; Zorzi, Nicola; Rummler, Andre; Weingarten, Jens

    2017-01-01

    this paper the performance of these modules are reported. In particular the lateral extension of the detection volume, beyond the pixel region, is investigated and the results show high hit efficiency also at the detector edge, even in presence of guard rings.

  14. Dynamic holography using pixelated light modulators.

    Science.gov (United States)

    Zwick, Susanne; Haist, Tobias; Warber, Michael; Osten, Wolfgang

    2010-09-01

    Dynamic holography using spatial light modulators is a very flexible technique that offers various new applications compared to static holography. We give an overview on the technical background of dynamic holography focusing on pixelated spatial light modulators and their technical restrictions, and we present a selection of the numerous applications of dynamic holography.

  15. A 128 pixel linear array for radiotherapy quality assurance

    Science.gov (United States)

    Franco, L.; Gómez, F.; Iglesias, A.; Lobato, R.; Marín, J.; Mosquera, J.; Pardo, J.; Pazos, A.; Pena, J.; Pombar, M.; Rodríguez, A.; Saavedra, D.; Sendón, J.; Yañez, A.

    2004-12-01

    New radiotherapy techniques require detectors able to verify and monitor the clinical beam with high spatial resolution and fast response. Room temperature organic liquid ionization detectors are becoming an alternative to standard air ionization chambers, due to their tissue equivalent behavior, their sensibility and small directional dependence. A liquid isooctane filled ionization linear array for radiotherapy quality assurance has been designed, built and tested. The detector consists of 128 pixels, each of them with an area of 1.7 mm×1.7 mm and a gap of 0.5 mm. The small pixel size makes the detector ideal for high gradient beam profiles like those present in Intensity Modulated Radiation Therapy. The gap and the polarization voltage have been chosen in order to guarantee a linear relationship between the dose rate and the readout signal at high dose rates. As readout electronics we use the X-ray Data Acquisition System with the Xchip developed by the CCLRC.In the first device tests we have confirmed linearity up to a 6.7 Gy/min dose rate with a deviation less than 1%. A profile with a signal-to-noise ratio around 500 can be obtained for a 4 Gy/min dose rate with a 10 ms integration time.

  16. A 128 pixel linear array for radiotherapy quality assurance

    Energy Technology Data Exchange (ETDEWEB)

    Franco, L. [Departmento de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, campus sur s/n, 15782 Santiago de Compostela (Spain); Gomez, F. [Departmento de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, campus sur s/n, 15782 Santiago de Compostela (Spain)]. E-mail: faustgr@usc.es; Iglesias, A. [Departmento de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, campus sur s/n, 15782 Santiago de Compostela (Spain); Lobato, R. [Hospital Clinico Universitario de Santiago, 15706 Santiago (Spain); Marin, J. [CIEMAT, Laboratorio de Electronica y Automatica, 28040 Madrid Spain (Spain); Mosquera, J. [Hospital Clinico Universitario de Santiago, 15706 Santiago (Spain); Pardo, J. [Departmento de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, campus sur s/n, 15782 Santiago de Compostela (Spain)]. E-mail: juanpm@usc.es; Pazos, A. [Departmento de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, campus sur s/n, 15782 Santiago de Compostela (Spain); Pena, J. [Departmento de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, campus sur s/n, 15782 Santiago de Compostela (Spain); Pombar, M. [Hospital Clinico Universitario de Santiago, 15706 Santiago (Spain); Rodriguez, A. [Departmento de Fisica de Particulas, Facultade de Fisica, Universidade de Santiago, campus sur s/n, 15782 Santiago de Compostela (Spain); Saavedra, D. [Universidade da Coruna, Dpto. de Enxeneria Industrial II, 15403 Ferrol Spain (Spain); Sendon, J. [Hospital Clinico Universitario de Santiago, 15706 Santiago (Spain); Yanez, A. [Universidade da Coruna, Dpto. de Enxeneria Industrial II, 15403 Ferrol Spain (Spain)

    2004-12-11

    New radiotherapy techniques require detectors able to verify and monitor the clinical beam with high spatial resolution and fast response. Room temperature organic liquid ionization detectors are becoming an alternative to standard air ionization chambers, due to their tissue equivalent behavior, their sensibility and small directional dependence. A liquid isooctane filled ionization linear array for radiotherapy quality assurance has been designed, built and tested. The detector consists of 128 pixels, each of them with an area of 1.7mmx1.7mm and a gap of 0.5mm. The small pixel size makes the detector ideal for high gradient beam profiles like those present in Intensity Modulated Radiation Therapy. The gap and the polarization voltage have been chosen in order to guarantee a linear relationship between the dose rate and the readout signal at high dose rates. As readout electronics we use the X-ray Data Acquisition System with the Xchip developed by the CCLRC.In the first device tests we have confirmed linearity up to a 6.7Gy/min dose rate with a deviation less than 1%. A profile with a signal-to-noise ratio around 500 can be obtained for a 4Gy/min dose rate with a 10 ms integration time.

  17. Pixel hybrid photon detector magnetic distortions characterization and compensation

    CERN Document Server

    Aglieri-Rinella, G; D'Ambrosio, Carmelo; Forty, Roger W; Gys, Thierry; Patel, Mitesh; Piedigrossi, Didier; Van Lysebetten, Ann

    2004-01-01

    The LHCb experiment requires positive kaon identification in the momentum range 2-100 GeV/c. This is provided by two ring imaging Cherenkov detectors. The stringent requirements on the photon detectors are fully satisfied by the novel pixel hybrid photon detector, HPD. The HPD is a vacuum tube with a quartz window, S20 photo-cathode, cross-focusing electron optics and a silicon anode encapsulated within the tube. The anode is a 32*256 pixels hybrid detector, with a silicon sensor bump-bonded onto a readout chip containing 8192 channels with analogue front-end and digital read-out circuitry. An external magnetic field influences the trajectory of the photoelectrons and could thereby degrade the inherent excellent space resolution of the HPD. The HPDs must be operational in the fringe magnetic field of the LHCb magnet. This paper reports on an extensive experimental characterization of the distortion effects. The characterization has allowed the development of parameterisations and of a compensation algorithm. ...

  18. Adaptive bad pixel correction algorithm for IRFPA based on PCNN

    Science.gov (United States)

    Leng, Hanbing; Zhou, Zuofeng; Cao, Jianzhong; Yi, Bo; Yan, Aqi; Zhang, Jian

    2013-10-01

    Bad pixels and response non-uniformity are the primary obstacles when IRFPA is used in different thermal imaging systems. The bad pixels of IRFPA include fixed bad pixels and random bad pixels. The former is caused by material or manufacture defect and their positions are always fixed, the latter is caused by temperature drift and their positions are always changing. Traditional radiometric calibration-based bad pixel detection and compensation algorithm is only valid to the fixed bad pixels. Scene-based bad pixel correction algorithm is the effective way to eliminate these two kinds of bad pixels. Currently, the most used scene-based bad pixel correction algorithm is based on adaptive median filter (AMF). In this algorithm, bad pixels are regarded as image noise and then be replaced by filtered value. However, missed correction and false correction often happens when AMF is used to handle complex infrared scenes. To solve this problem, a new adaptive bad pixel correction algorithm based on pulse coupled neural networks (PCNN) is proposed. Potential bad pixels are detected by PCNN in the first step, then image sequences are used periodically to confirm the real bad pixels and exclude the false one, finally bad pixels are replaced by the filtered result. With the real infrared images obtained from a camera, the experiment results show the effectiveness of the proposed algorithm.

  19. The power of low-resolution spectroscopy: On the spectral classification of planet candidates in the ground-based CoRoT follow-up

    CERN Document Server

    Eiff, M Ammler-von; Guenther, E W; Stecklum, B; Cabrera, J

    2015-01-01

    Planetary transits detected by the CoRoT mission can be mimicked by a low-mass star in orbit around a giant star. Spectral classification helps to identify the giant stars and also early-type stars which are often excluded from further follow-up. We study the potential and the limitations of low-resolution spectroscopy to improve the photometric spectral types of CoRoT candidates. In particular, we want to study the influence of the signal-to-noise ratio (SNR) of the target spectrum in a quantitative way. We built an own template library and investigate whether a template library from the literature is able to reproduce the classifications. Including previous photometric estimates, we show how the additional spectroscopic information improves the constraints on spectral type. Low-resolution spectroscopy ($R\\approx$1000) of 42 CoRoT targets covering a wide range in SNR (1-437) and of 149 templates was obtained in 2012-2013 with the Nasmyth spectrograph at the Tautenburg 2m telescope. Spectral types have been d...

  20. Pixel Read-Out Architectures for the NA62 GigaTracker

    CERN Document Server

    Dellacasa, G

    2008-01-01

    Beam particles in NA62 experiment are measured with a Si-pixel sensor having a size of 300 μm x 300 μm and a time resolution of 150 ps (rms). To meet the timing requirement an adequate strategy to compensate the discriminator time-walk must be implemented and an R&D effort investigating two different options is ongoing. In this presentation we describe the two different approaches. One is based on the use of a constant-fraction discriminator followed by an on-pixel TDC. The other one is based on the use of a Time-over-Threshold circuit followed by a TDC shared by a group of pixels. The global architectures of both the front-end ASIC will be discussed.

  1. Development and characterization of a DEPFET pixel prototype system for the ILC vertex detector

    Energy Technology Data Exchange (ETDEWEB)

    Kohrs, Robert

    2008-09-15

    For the future TeV-scale linear collider ILC (International Linear Collider) a vertex detector of unprecedented performance is needed to fully exploit its physics potential. By incorporating a field effect transistor into a fully depleted sensor substrate the DEPFET (Depleted Field Effect Transistor) sensor combines radiation detection and in-pixel amplification. For the operation at a linear collider the excellent noise performance of DEPFET pixels allows building very thin detectors with a high spatial resolution and a low power consumption. With this thesis a prototype system consisting of a 64 x 128 pixels sensor, dedicated steering and readout ASICs and a data acquisition board has been developed and successfully operated in the laboratory and under realistic conditions in beam test environments at DESY and CERN. A DEPFET matrix has been successfully read out using the on-chip zero-suppression of the readout chip CURO 2. The results of the system characterization and beam test results are presented. (orig.)

  2. Operational experience with the CMS pixel detector in LHC Run II

    CERN Document Server

    Karancsi, Janos

    2016-01-01

    The CMS pixel detector was repaired successfully, calibrated and commissioned for the second run of Large Hadron Collider during the first long shutdown between 2013 and 2015. The replaced pixel modules were calibrated separately and show the expected behavior of an un-irradiated detector. In 2015, the system performed very well with an even improved spatial resolution compared to 2012. During this time, the operational team faced various challenges including the loss of a sector in one half shell which was only partially recovered. In 2016, the detector is expected to withstand instantaneous luminosities beyond the design limits and will need a combined effort of both online and offline teams in order to provide the high quality data that is required to reach the physics goals of CMS. We present the operational experience gained during the second run of the LHC and show the latest performance results of the CMS pixel detector.

  3. Analysis of the 2006 block-and-ash flow deposits of Merapi Volcano, Java, Indonesia, using high-spatial resolution IKONOS images and complementary ground based observations

    Science.gov (United States)

    Thouret, Jean-Claude; Gupta, Avijit; Liew, Soo Chin; Lube, Gert; Cronin, Shane J.; Surono, Dr

    2010-05-01

    On 16 June 2006 an overpass of IKONOS coincided with the emplacement of an active block-and-ash flow fed by a lava dome collapse event at Merapi Volcano (Java, Indonesia). This was the first satellite image recorded for a moving pyroclastic flow. The very high-spatial resolution data displayed the extent and impact of the pyroclastic deposits emplaced during and prior to, the day of image acquisition. This allowed a number of features associated with high-hazard block-and-ash flows emplaced in narrow, deep gorges to be mapped, interpreted and understood. The block-and-ash flow and surge deposits recognized in the Ikonos images include: (1) several channel-confined flow lobes and tongues in the box-shaped valley; (2) thin ash-cloud surge deposit and knocked-down trees in constricted areas on both slopes of the gorge; (3) fan-like over bank deposits on the Gendol-Tlogo interfluves from which flows were re-routed in the Tlogo secondary valley; (4) massive over bank lobes on the right bank from which flows devastated the village of Kaliadem 0.5 km from the main channel, a small part of this flow being re-channeled in the Opak secondary valley. The high-resolution IKONOS images also helped us to identify geomorphic obstacles that enabled flows to ramp and spill out from the sinuous channel, a process called flow avulsion. Importantly, the avulsion redirected flows to unexpected areas away from the main channel. In the case of Merapi we see that the presence of valley fill by previous deposits, bends and man-made dams influence the otherwise valley-guided course of the flows. Sadly, Sabo dams (built to ameliorate the effect of high sediment load streams) can actually cause block-and-ash flows to jump out of their containing channel and advance into sensitive areas. Very-high-spatial resolution satellite images are very useful for mapping and interpreting the distribution of freshly erupted volcanic deposits. IKONOS-type images with 1-m resolution provide opportunities to

  4. Sub-pixel calibration for Weak Lensing and Astrometry

    Science.gov (United States)

    Shao, Michael

    WFIRST together. Specifically, we propose to develop a pre-flight ground-based characterization of the detector arrays on WIRST using our laser metrology technique. As such, the new technique offers unique capabilities for investigation of exoplanets with WFIRST. We plan to study these exciting science possibilities. We propose a 3-year program focused on the improvement, development, and application of our new technique of sub-pixel detector calibration. This proposal has several major objectives: 1. To extend our work on ultra-precise centroiding of images to the removal of image shape bias that is relevant to the weak lensing campaign on WFIRST. Ultra-precise sub-pixel calibration also enables very high photometric accuracy, similar to that on Kepler mission. We also intend to expand beyond astrometric application of sub-pixel characterization to shape bias removal and precise photometry. Much of this work can proceed using our data from CCDs. 2. To extend the applicability of our technique from optical to NIR detectors and demonstrate this new technique to the H2RG detectors. The results of this work will be directly applicable to H4RG-10 detectors, which we wish to calibrate, once they will become available. We will develop data analysis methods relevant to weak lensing surveys on WFIRST by providing a proper account for the detector systematics, essentially eliminating their contribution. 3. To explore the science implication of the high-precision astrometric measurements on WFIRST that may be possible at the level of 4 μas. To investigate the science possibilities of ultra-precise astrometry and/or photometry on WFIRST, including exoplanet astrometry of super Earths, exoplanet transit observations, determination of masses of binary stars where one component is a neutron star or black hole.

  5. Silicon sensors development for the CMS pixel system

    CERN Document Server

    Arndt, Kirk; Bortoletto, Daniela; Giolo, Kim; Horisberger, R P; Rohe, T; Roy, Amitava; Son Seung Hee

    2003-01-01

    The CMS experiment will operate at the Large Hadron Collider (LHC). A hybrid pixel detector located close to the interaction region of the colliding beams will provide high resolution tracking and vertex identification which will be crucial for b quark identification. Because of the radiation environment of the LHC, the performance of the sensors must be carefully evaluated up to a fluence of 6 multiplied by 10**1**4n//e//qcm **-**2. We expect that the sensors will be operated partially depleted during their operation at the LHC and we have implemented an n**+ on n sensor design. We have irradiated prototype sensors to a dose of 1 multiplied by 10 **1**5n //e//qcm**-**2. We present the results of our testing before and after irradiation.

  6. Line profile modelling for multi-pixel CZT detectors

    Science.gov (United States)

    Chattopadhyay, T.; Vadawale, S. V.; Rao, A. R.; Bhattacharya, D.; Mithun, N. P. S.; Bhalerao, V.

    2016-07-01

    Cadmium Zinc Telluride (CZT) detectors have been the mainstay for hard X-ray astronomy for its high quantum efficiency, fine energy resolution, near room temperature operation, and radiation hardness. In order to fully utilize the spectroscopic capabilities of CZT detectors, it is important to generate accurate response matrix, which in turn requires precise modelling of the line profiles for the CZT detectors. We have developed a numerical model taking into account the mobility and lifetime of the charge carriers and intrpixel charge sharing for the CZT detectors. This paper describes the details of the modelling along with the experimental measurements of mobility, lifetime and charge sharing fractions for the CZT detector modules of thickness of 5 mm and 2.5 mm pixel size procured from Orbotech Medical Solutions (same modules used in AstroSat-CZTI).

  7. Design Methodology: ASICs with complex in-pixel processing for Pixel Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Fahim, Farah [Fermilab

    2014-10-31

    The development of Application Specific Integrated Circuits (ASIC) for pixel detectors with complex in-pixel processing using Computer Aided Design (CAD) tools that are, themselves, mainly developed for the design of conventional digital circuits requires a specialized approach. Mixed signal pixels often require parasitically aware detailed analog front-ends and extremely compact digital back-ends with more than 1000 transistors in small areas below 100μm x 100μm. These pixels are tiled to create large arrays, which have the same clock distribution and data readout speed constraints as in, for example, micro-processors. The methodology uses a modified mixed-mode on-top digital implementation flow to not only harness the tool efficiency for timing and floor-planning but also to maintain designer control over compact parasitically aware layout.

  8. UBC ScanCam: an inexpensive 122-million pixel scan camera

    Science.gov (United States)

    Wang, Shuzhen; Heidrich, Wolfgang

    2004-06-01

    We describe the design of a very high resolution, low-cost scan camera for use in image-based modeling and rendering, cultural heritage projects, and professional digital photography. Our camera can acquire black&white, color, and nearinfrared images with a resolution of over 122 million pixels and can be readily built from off-the-shelf components for less than $1200. We discuss the construction of the system as well as color calibration and noise removal. Finally, we obtain quantitative measurements of the light sensitivity and the optical resolution of our camera and compare the image quality to a commercial digital SLR camera.

  9. Design methodology: edgeless 3D ASICs with complex in-pixel processing for pixel detectors

    Energy Technology Data Exchange (ETDEWEB)

    Fahim Farah, Fahim Farah [Northwestern U. (main); Deptuch, Grzegorz W. [Fermilab; Hoff, James R. [Fermilab; Mohseni, Hooman [Northwestern U. (main)

    2015-08-28

    The design methodology for the development of 3D integrated edgeless pixel detectors with in-pixel processing using Electronic Design Automation (EDA) tools is presented. A large area 3 tier 3D detector with one sensor layer and two ASIC layers containing one analog and one digital tier, is built for x-ray photon time of arrival measurement and imaging. A full custom analog pixel is 65μm x 65μm. It is connected to a sensor pixel of the same size on one side, and on the other side it has approximately 40 connections to the digital pixel. A 32 x 32 edgeless array without any peripheral functional blocks constitutes a sub-chip. The sub-chip is an indivisible unit, which is further arranged in a 6 x 6 array to create the entire 1.248cm x 1.248cm ASIC. Each chip has 720 bump-bond I/O connections, on the back of the digital tier to the ceramic PCB. All the analog tier power and biasing is conveyed through the digital tier from the PCB. The assembly has no peripheral functional blocks, and hence the active area extends to the edge of the detector. This was achieved by using a few flavors of almost identical analog pixels (minimal variation in layout) to allow for peripheral biasing blocks to be placed within pixels. The 1024 pixels within a digital sub-chip array have a variety of full custom, semi-custom and automated timing driven functional blocks placed together. The methodology uses a modified mixed-mode on-top digital implementation flow to not only harness the tool efficiency for timing and floor-planning but also to maintain designer control over compact parasitically aware layout. The methodology uses the Cadence design platform, however it is not limited to this tool.

  10. PixelSNE: Visualizing Fast with Just Enough Precision via Pixel-Aligned Stochastic Neighbor Embedding

    OpenAIRE

    Kim, Minjeong; Choi, Minsuk; Lee, Sunwoong; Tang, Jian; Park, Haesun; Choo, Jaegul

    2016-01-01

    Embedding and visualizing large-scale high-dimensional data in a two-dimensional space is an important problem since such visualization can reveal deep insights out of complex data. Most of the existing embedding approaches, however, run on an excessively high precision, ignoring the fact that at the end, embedding outputs are converted into coarse-grained discrete pixel coordinates in a screen space. Motivated by such an observation and directly considering pixel coordinates in an embedding ...

  11. Pyramidal fractal dimension for high resolution images

    Science.gov (United States)

    Mayrhofer-Reinhartshuber, Michael; Ahammer, Helmut

    2016-07-01

    Fractal analysis (FA) should be able to yield reliable and fast results for high-resolution digital images to be applicable in fields that require immediate outcomes. Triggered by an efficient implementation of FA for binary images, we present three new approaches for fractal dimension (D) estimation of images that utilize image pyramids, namely, the pyramid triangular prism, the pyramid gradient, and the pyramid differences method (PTPM, PGM, PDM). We evaluated the performance of the three new and five standard techniques when applied to images with sizes up to 8192 × 8192 pixels. By using artificial fractal images created by three different generator models as ground truth, we determined the scale ranges with minimum deviations between estimation and theory. All pyramidal methods (PM) resulted in reasonable D values for images of all generator models. Especially, for images with sizes ≥1024 ×1024 pixels, the PMs are superior to the investigated standard approaches in terms of accuracy and computation time. A measure for the possibility to differentiate images with different intrinsic D values did show not only that the PMs are well suited for all investigated image sizes, and preferable to standard methods especially for larger images, but also that results of standard D estimation techniques are strongly influenced by the image size. Fastest results were obtained with the PDM and PGM, followed by the PTPM. In terms of absolute D values best performing standard methods were magnitudes slower than the PMs. Concluding, the new PMs yield high quality results in short computation times and are therefore eligible methods for fast FA of high-resolution images.

  12. Fully 3D-Integrated Pixel Detectors for X-Rays

    Energy Technology Data Exchange (ETDEWEB)

    Deptuch, Grzegorz W. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Gabriella, Carini [SLAC National Accelerator Lab., Menlo Park, CA (United States); Enquist, Paul [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Grybos, Pawel [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Holm, Scott [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Lipton, Ronald [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Maj, Piotr [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Patti, Robert [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Siddons, David Peter [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Szczygiel, Robert [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Yarema, Raymond [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2016-01-01

    The vertically integrated photon imaging chip (VIPIC1) pixel detector is a stack consisting of a 500-μm-thick silicon sensor, a two-tier 34-μm-thick integrated circuit, and a host printed circuit board (PCB). The integrated circuit tiers were bonded using the direct bonding technology with copper, and each tier features 1-μm-diameter through-silicon vias that were used for connections to the sensor on one side, and to the host PCB on the other side. The 80-μm-pixel-pitch sensor was the direct bonding technology with nickel bonded to the integrated circuit. The stack was mounted on the board using Sn–Pb balls placed on a 320-μm pitch, yielding an entirely wire-bond-less structure. The analog front-end features a pulse response peaking at below 250 ns, and the power consumption per pixel is 25 μW. We successful completed the 3-D integration and have reported here. Additionally, all pixels in the matrix of 64 × 64 pixels were responding on well-bonded devices. Correct operation of the sparsified readout, allowing a single 153-ns bunch timing resolution, was confirmed in the tests on a synchrotron beam of 10-keV X-rays. An equivalent noise charge of 36.2 e- rms and a conversion gain of 69.5 μV/e- with 2.6 e- rms and 2.7 μV/e- rms pixel-to-pixel variations, respectively, were measured.

  13. ALPIDE, the Monolithic Active Pixel Sensor for the ALICE ITS upgrade

    Science.gov (United States)

    Mager, M.

    2016-07-01

    A new 10 m2 inner tracking system based on seven concentric layers of Monolithic Active Pixel Sensors will be installed in the ALICE experiment during the second long shutdown of LHC in 2019-2020. The monolithic pixel sensors will be fabricated in the 180 nm CMOS Imaging Sensor process of TowerJazz. The ALPIDE design takes full advantage of a particular process feature, the deep p-well, which allows for full CMOS circuitry within the pixel matrix, while at the same time retaining the full charge collection efficiency. Together with the small feature size and the availability of six metal layers, this allowed a continuously active low-power front-end to be placed into each pixel and an in-matrix sparsification circuit to be used that sends only the addresses of hit pixels to the periphery. This approach led to a power consumption of less than 40 mWcm-2, a spatial resolution of around 5 μm, a peaking time of around 2 μs, while being radiation hard to some 1013 1 MeVneq /cm2, fulfilling or exceeding the ALICE requirements. Over the last years of R & D, several prototype circuits have been used to verify radiation hardness, and to optimize pixel geometry and in-pixel front-end circuitry. The positive results led to a submission of full-scale (3 cm×1.5 cm) sensor prototypes in 2014. They are being characterized in a comprehensive campaign that also involves several irradiation and beam tests. A summary of the results obtained and prospects towards the final sensor to instrument the ALICE Inner Tracking System are given.

  14. ACS/WFC Pixel Stability - Bringing the Pixels Back to the Science

    Science.gov (United States)

    Borncamp, David; Grogin, Norman A.; Bourque, Matthew; Ogaz, Sara

    2016-06-01

    Electrical current that has been trapped within the lattice structure of a Charged Coupled Device (CCD) can be present through multiple exposures, which will have an adverse effect on its science performance. The traditional way to correct for this extra charge is to take an image with the camera shutter closed periodically throughout the lifetime of the instrument. These images, generally referred to as dark images, allow for the characterization of the extra charge that is trapped within the CCD at the time of observation. This extra current can then be subtracted out of science images to correct for the extra charge that was there at this time. Pixels that have a charge above a certain threshold of current are marked as “hot” and flagged in the data quality array. However, these pixels may not be "bad" in the traditional sense that they cannot be reliably dark-subtracted. If these pixels are shown to be stable over an anneal period, the charge can be properly subtracted and the extra noise from this dark current can be taken into account. We present the results of a pixel history study that analyzes every pixel of ACS/WFC individually and allows pixels that were marked as bad to be brought back into the science image.

  15. Adaptive foveated single-pixel imaging with dynamic super-sampling

    CERN Document Server

    Phillips, David B; Taylor, Jonathan M; Edgar, Matthew P; Barnett, Stephen M; Gibson, Graham G; Padgett, Miles J

    2016-01-01

    As an alternative to conventional multi-pixel cameras, single-pixel cameras enable images to be recorded using a single detector that measures the correlations between the scene and a set of patterns. However, to fully sample a scene in this way requires at least the same number of correlation measurements as there are pixels in the reconstructed image. Therefore single-pixel imaging systems typically exhibit low frame-rates. To mitigate this, a range of compressive sensing techniques have been developed which rely on a priori knowledge of the scene to reconstruct images from an under-sampled set of measurements. In this work we take a different approach and adopt a strategy inspired by the foveated vision systems found in the animal kingdom - a framework that exploits the spatio-temporal redundancy present in many dynamic scenes. In our single-pixel imaging system a high-resolution foveal region follows motion within the scene, but unlike a simple zoom, every frame delivers new spatial information from acros...

  16. A new generation of small pixel pitch/SWaP cooled infrared detectors

    Science.gov (United States)

    Espuno, L.; Pacaud, O.; Reibel, Y.; Rubaldo, L.; Kerlain, A.; Péré-Laperne, N.; Dariel, A.; Roumegoux, J.; Brunner, A.; Kessler, A.; Gravrand, O.; Castelein, P.

    2015-10-01

    Following clear technological trends, the cooled IR detectors market is now in demand for smaller, more efficient and higher performance products. This demand pushes products developments towards constant innovations on detectors, read-out circuits, proximity electronics boards, and coolers. Sofradir was first to show a 10μm focal plane array (FPA) at DSS 2012, and announced the DAPHNIS 10μm product line back in 2014. This pixel pitch is a key enabler for infrared detectors with increased resolution. Sofradir recently achieved outstanding products demonstrations at this pixel pitch, which clearly demonstrate the benefits of adopting 10μm pixel pitch focal plane array-based detectors. Both HD and XGA Daphnis 10μm products also benefit from a global video datapath efficiency improvement by transitioning to digital video interfaces. Moreover, innovative smart pixels functionalities drastically increase product versatility. In addition to this strong push towards a higher pixels density, Sofradir acknowledges the need for smaller and lower power cooled infrared detector. Together with straightforward system interfaces and better overall performances, latest technological advances on SWAP-C (Size, Weight, Power and Cost) Sofradir products enable the advent of a new generation of high performance portable and agile systems (handheld thermal imagers, unmanned aerial vehicles, light gimbals etc...). This paper focuses on those features and performances that can make an actual difference in the field.

  17. Compact SPAD-Based Pixel Architectures for Time-Resolved Image Sensors.

    Science.gov (United States)

    Perenzoni, Matteo; Pancheri, Lucio; Stoppa, David

    2016-05-23

    This paper reviews the state of the art of single-photon avalanche diode (SPAD) image sensors for time-resolved imaging. The focus of the paper is on pixel architectures featuring small pixel size (20%) as a key enabling technology for the successful implementation of high spatial resolution SPAD-based image sensors. A summary of the main CMOS SPAD implementations, their characteristics and integration challenges, is provided from the perspective of targeting large pixel arrays, where one of the key drivers is the spatial uniformity. The main analog techniques aimed at time-gated photon counting and photon timestamping suitable for compact and low-power pixels are critically discussed. The main features of these solutions are the adoption of analog counting techniques and time-to-analog conversion, in NMOS-only pixels. Reliable quantum-limited single-photon counting, self-referenced analog-to-digital conversion, time gating down to 0.75 ns and timestamping with 368 ps jitter are achieved.

  18. Compact SPAD-Based Pixel Architectures for Time-Resolved Image Sensors

    Directory of Open Access Journals (Sweden)

    Matteo Perenzoni

    2016-05-01

    Full Text Available This paper reviews the state of the art of single-photon avalanche diode (SPAD image sensors for time-resolved imaging. The focus of the paper is on pixel architectures featuring small pixel size (<25 μm and high fill factor (>20% as a key enabling technology for the successful implementation of high spatial resolution SPAD-based image sensors. A summary of the main CMOS SPAD implementations, their characteristics and integration challenges, is provided from the perspective of targeting large pixel arrays, where one of the key drivers is the spatial uniformity. The main analog techniques aimed at time-gated photon counting and photon timestamping suitable for compact and low-power pixels are critically discussed. The main features of these solutions are the adoption of analog counting techniques and time-to-analog conversion, in NMOS-only pixels. Reliable quantum-limited single-photon counting, self-referenced analog-to-digital conversion, time gating down to 0.75 ns and timestamping with 368 ps jitter are achieved.

  19. Mass test of AdvanSiD model ASD-NUV3S-P SiliconPMs for the Pixel Timing Counter of the MEG II experiment

    Science.gov (United States)

    Rossella, M.; Bariani, S.; Barnaba, O.; Cattaneo, P. W.; Cervi, T.; Menegolli, A.; Nardò, R.; Prata, M. C.; Romano, E.; Scagliotti, C.; Simonetta, M.; Vercellati, F.

    2017-02-01

    The MEG II Timing Counter will measure the positron time of arrival with a resolution of 30 ps relying on two arrays of scintillator pixels read out by 6144 Silicon Photomultipliers (SiPMs) from AdvanSiD. They must be characterized, measuring their breakdown voltage, to assure that the gains of the SiPMs of each pixel are as uniform as possible, to maximize the pixel resolution. To do this an automatic test system that can measure sequentially the parameters of 32 devices has been developed.

  20. Upgrade of ATLAS ITk Pixel Detector

    CERN Document Server

    Huegging, Fabian; The ATLAS collaboration

    2017-01-01

    The high luminosity upgrade of the LHC (HL-LHC) in 2026 will provide new challenges to the ATLAS tracker. The current inner detector will be replaced with an entirely-silicon inner tracker (ITk) which will consist of a five barrel layer Pixel detector surrounded by a four barrel layer Strip detector. The expected high radiation levels are requiring the development of upgraded silicon sensors as well as new a front-end chip. The dense tracking environment will require finer granularity detectors and low mass global and local support structures. The data rates will require new technologies for high bandwidth data transmission and handling. The current status of the ITk ATLAS Pixel detector developments as well as different layout options will be reviewed.

  1. Monolithic pixel detectors for high energy physics

    CERN Document Server

    Snoeys, W

    2013-01-01

    Monolithic pixel detectors integrating sensor matrix and readout in one piece of silicon have revolutionized imaging for consumer applications, but despite years of research they have not yet been widely adopted for high energy physics. Two major requirements for this application, radiation tolerance and low power consumption, require charge collection by drift for the most extreme radiation levels and an optimization of the collected signal charge over input capacitance ratio ( Q / C ). It is shown that monolithic detectors can achieve Q / C for low analog power consumption and even carryout the promise to practically eliminate analog power consumption, but combining suf fi cient Q / C , collection by drift, and integration of readout circuitry within the pixel remains a challenge. An overview is given of different approaches to address this challenge, with possible advantages and disadvantages.

  2. Noise in a CMOS digital pixel sensor

    Institute of Scientific and Technical Information of China (English)

    Zhang Chi; Yao Suying; Xu Jiangtao

    2011-01-01

    Based on the study of noise performance in CMOS digital pixel sensor (DPS),a mathematical model of noise is established with the pulse-width-modulation (PWM) principle.Compared with traditional CMOS image sensors,the integration time is different and A/D conversion is implemented in each PWM DPS pixel.Then,the quantitative calculating formula of system noise is derived.It is found that dark current shot noise is the dominant noise source in low light region while photodiode shot noise becomes significantly important in the bright region.In this model,photodiode shot noise does not vary with luminance,but dark current shot noise does.According to increasing photodiode capacitance and the comparator's reference voltage or optimizing the mismatch in the comparator,the total noise can be reduced.These results serve as a guideline for the design of PWM DPS.

  3. ATLAS Pixel IBL: Stave Quality Assurance

    CERN Document Server

    The ATLAS collaboration

    2014-01-01

    For Run 2 of the LHC a fourth innermost Pixel Detector layer on a smaller radius beam pipe has been installed in the ATLAS Detector to add redundancy against radiation damage of the current Pixel Detector and to ensure a high quality tracking and b-tagging performance of the Inner Detector over the coming years until the High Luminosity Upgrade. State of the art components have been produced and assembled onto support structures known as staves over the last two years. In total, 20 staves have been built and qualified in a designated Quality Assurance setup at CERN of which 14 have been integrated onto the beam pipe. Results from the testing are presented.

  4. High resolution shallow geologic characterization of a late Pleistocene eolian environment using ground penetrating radar and optically stimulated luminescence techniques: North Carolina, USA

    Science.gov (United States)

    Mallinson, D.; Mahan, S.; Moore, Christine

    2008-01-01

    Geophysical surveys, sedimentology, and optically-stimulated luminescence age analyses were used to assess the geologic development of a coastal system near Swansboro, NC. This area is a significant Woodland Period Native American habitation and is designated the "Broad Reach" archaeological site. 2-d and 3-d subsurface geophysical surveys were performed using a ground penetrating radar system to define the stratigraphic framework and depositional facies. Sediment samples were collected and analyzed for grain-size to determine depositional environments. Samples were acquired and analyzed using optically stimulated luminescence techniques to derive the depositional age of the various features. The data support a low eolian to shallow subtidal coastal depositional setting for this area. Li-DAR data reveal ridge and swale topography, most likely related to beach ridges, and eolian features including low-relief, low-angle transverse and parabolic dunes, blowouts, and a low-relief eolian sand sheet. Geophysical data reveal dominantly seaward dipping units, and low-angle mounded features. Sedimentological data reveal mostly moderately-well to well-sorted fine-grained symmetrical to coarse skewed sands, suggesting initial aqueous transport and deposition, followed by eolian reworking and bioturbation. OSL data indicate initial coastal deposition prior to ca. 45,000 yBP, followed by eolian reworking and low dune stabilization at ca. 13,000 to 11,500 yBP, and again at ca. 10,000 yBP (during, and slightly after the Younger Dryas chronozone).

  5. The Belle II DEPFET pixel detector

    Energy Technology Data Exchange (ETDEWEB)

    Moser, Hans-Günther, E-mail: moser@mpp.mpg.de

    2016-09-21

    The Belle II experiment at KEK (Tsukuba, Japan) will explore heavy flavour physics (B, charm and tau) at the starting of 2018 with unprecedented precision. Charged particles are tracked by a two-layer DEPFET pixel device (PXD), a four-layer silicon strip detector (SVD) and the central drift chamber (CDC). The PXD will consist of two layers at radii of 14 mm and 22 mm with 8 and 12 ladders, respectively. The pixel sizes will vary, between 50 μm×(55–60) μm in the first layer and between 50 μm×(70–85) μm in the second layer, to optimize the charge sharing efficiency. These innermost layers have to cope with high background occupancy, high radiation and must have minimal material to reduce multiple scattering. These challenges are met using the DEPFET technology. Each pixel is a FET integrated on a fully depleted silicon bulk. The signal charge collected in the ‘internal gate’ modulates the FET current resulting in a first stage amplification and therefore very low noise. This allows very thin sensors (75 μm) reducing the overall material budget of the detector (0.21% X{sub 0}). Four fold multiplexing of the column parallel readout allows read out a full frame of the pixel matrix in only 20 μs while keeping the power consumption low enough for air cooling. Only the active electronics outside the detector acceptance has to be cooled actively with a two phase CO{sub 2} system. Furthermore the DEPFET technology offers the unique feature of an electronic shutter which allows the detector to operate efficiently in the continuous injection mode of superKEKB.

  6. Pixel Dynamics Analysis of Photospheric Spectral Data

    Science.gov (United States)

    2014-11-13

    corresponding Doppler blueshift (redshift) integrated over the pixel. Variations in the line width δλm may indicate variations in temperature or changes in...skewness of their absorption line redshift/ blueshift and asymmetry PFDs, as well as by the spatial average for each region. These three time-varying... blueshift PFD variance and skewness plots). These oscillations, associated with the AR regions exhibiting solar eruptions, occur with a period of ∼ 10

  7. Efficient segmentation by sparse