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X-ray fluorescence imaging system for fast mapping of pigment distributions in cultural heritage paintings

JOURNAL OF INSTRUMENTATION 2013年第10期8卷 P10011-P10011页

作者： Zielinska, A. Dabrowski, W. Fiutowski, T. Mindur, B. Wiacek, P. Wrobel, P. AGH Univ Sci & Technol Fac Phys & Appl Comp Sci Krakow Poland

Conventional X-ray fluorescence imaging technique uses a focused X-ray beam to scan through the sample and an X-ray detector with high energy resolution but no spatial resolution. The spatial resolution of the image is then determined by the size of the exciting beam, which can be obtained either from a synchrotron source or from an X-ray tube with a micro-capillary lens. Such a technique based on a pixel-by-pixel measurement is very slow and not suitable for imaging large area samples. The goal of this work is to develop a system capable of simultaneous imaging of large area samples by using a wide field uniform excitation X-ray beam and a position sensitive and energy dispersive detector. The development is driven by possible application of such a system to imaging of distributions of hidden pigments containing specific elements in cultural heritage paintings, which is of great interest for the cultural heritage research. The fluorescence radiation from the area of 10 x 10 cm(2) is projected through a pinhole camera on the Gas Electron Multiplier detector of the same area. The detector is equipped with two sets of orthogonal readout strips. The strips are read out by the GEMROC Application Specific Integrated Circuits (ASIC)s, which deliver time and amplitude information for each hit. This ASIC architecture combined with a Field Programmable Gate Array (FPGA) based readout system allows us to reconstruct the position and the total energy of each detected photon for high count rates up to 5 x 10(6) cps. Energy resolution better than 20% FWHM for the 5.9 keV line and spatial resolution of 1 mm FWHM have been achieved for the prototype system. Although the energy resolution of the Gas Electron Multiplier (GEM) detector is, by principle, not competitive with that of specialised high energy resolution semiconductor detectors, it is sufficient for a number of applications. Compared to conventional micro-XRF techniques the developed system allows shortening of the measur

关键词： Inspection with x-rays Gaseous imaging and tracking detectors X-ray fluorescence (XRF) systems data processing methods

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Calibration algorithms of RPC detectors at Daya Bay Neutrino Experiment

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JOURNAL OF INSTRUMENTATION 2013年第03期8卷 T03007-T03007页

作者： Ning, Z. Zhang, Q. M. Xu, J. L. Lebanowski, L. Zhang, J. W. Yang, C. G. He, M. Zhao, J. Zou, J. H. Pec, V. Lin, Sh. -K. Guan, M. Y. Hao, H. F. Zheng, L. Ji, X. L. Li, F. Lau, K. Vorobel, V. State Key Lab Particle Detect & Elect Beijing 100049 Peoples R China Xi An Jiao Tong Univ Xian 710049 Peoples R China Univ Chinese Acad Sci Beijing 100049 Peoples R China Chinese Acad Sci Inst High Energy Phys Beijing 100049 Peoples R China Univ Houston Dept Phys Houston TX 77204 USA Charles Univ Prague Fac Math & Phys CR-12116 Prague Czech Republic Univ Sci & Technol China Anhua 230026 Peoples R China

During the commissioning of RPC detector systems at the Daya Bay Reactor Neutrino Experiment, calibration algorithms were developed and tuned, in order to evaluate and optimize the performance of the RPC detectors. Based on a description of the hardware structure of the RPC detector systems, this paper introduces the algorithms used for detector calibration, including trigger rate, efficiency, noise rate, purity and muon flux.

关键词： Analysis and statistical methods data processing methods Simulation methods and programs

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Explosive detection using pixellated X-ray diffraction (PixD)

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JOURNAL OF INSTRUMENTATION 2013年第3期8卷 P03007-P03007页

作者： O'Flynn, D. Reid, C. B. Christodoulou, C. Wilson, M. D. Veale, M. C. Seller, P. Hills, D. Desai, H. Wong, B. Speller, R. UCL Dept Med Phys & Bioengn London WC1E 6BT England Rutherford Appleton Lab Detector Dev Grp Didcot OX11 0QX Oxon England Ctr Appl Sci & Technol Sandridge AL4 9HQ St Albans England Dept Transportat London SW1P 4DR England

A novel, pixellated, energy-resolving X-ray detector has been utilised to simultaneously combine angular and energy dispersive X-ray diffraction (XRD). This approach allows a system to measure XRD data using the benefits of both approaches. data acquisition is fast, and the system contains no moving parts, making it ideal for applications in security, particularly for the detection of explosive materials hidden within packages or baggage. Explosive samples supplied by the Centre for Applied Science and Technology, U. K. were examined using the pixellated diffraction technique, and the XRD data were compared with those from inert materials typically found inside luggage. A method of processing the data was developed, which greatly reduces the amount of data outputted from the detector whilst preserving the angular and energy resolution. Using principal component and discriminant analyses, a model was developed which predicts the correct classification of an unknown sample as either "explosive" or "inert" for data with acquisition times as low as one second.

关键词： data processing methods Pixelated detectors and associated VLSI electronics Detection of explosives X-ray diffraction detectors

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Comparing performances of a CdTe X-ray spectroscopic detector and an X-ray dual-energy sandwich detector

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JOURNAL OF INSTRUMENTATION 2013年第11期8卷 P11011-P11011页

作者： Gorecki, A. Brambilla, A. Moulin, V. Gaborieau, E. Radisson, P. Verger, L. CEA LETI MINATEC Dept Rech Technol F-38054 Grenoble 09 France MultiX F-38430 Moirans France

Multi-energy (ME) detectors are becoming a serious alternative to classical dual-energy sandwich (DE-S) detectors for X-ray applications such as medical imaging or explosive detection. They can use the full X-ray spectrum of irradiated materials, rather than disposing only of low and high energy measurements, which may be mixed. In this article, we intend to compare both simulated and real industrial detection systems, operating at a high count rate, independently of the dimensions of the measurements and independently of any signal processing methods. Simulations or prototypes of similar detectors have already been compared (see [1] for instance), but never independently of estimation methods and never with real detectors. We have simulated both an ME detector made of CdTe - based on the characteristics of the MultiX ME100 and - a DE-S detector - based on the characteristics of the Detection Technology's X-Card 1.5-64DE model. These detectors were compared to a perfect spectroscopic detector and an optimal DE-S detector. For comparison purposes, two approaches were investigated. The first approach addresses how to distinguise signals, while the second relates to identifying materials. Performance criteria were defined and comparisons were made over a range of material thicknesses and with different photon statistics. Experimental measurements in a specific configuration were acquired to checks simulations. Results showed good agreement between the ME simulation and the ME100 detector. Both criteria seem to be equivalent, and the ME detector performs 3.5 times better than the DE-S detector with same photon statistics based on simulations and experimental measurements. Regardless of the photon statistics ME detectors appeared more efficient than DE-S detectors for all material thicknesses between 1 and 9 cm when measuring plastics with an attenuation signature close that of explosive materials. This translates into an improved false detection rate (FDR): DE-S detecto

关键词： data processing methods Inspection with x-rays Detection of explosives

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uBoost: a boosting method for producing uniform selection efficiencies from multivariate classifiers

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JOURNAL OF INSTRUMENTATION 2013年第12期8卷 P12013-P12013页

作者： Stevens, J. Williams, M. MIT Cambridge MA 02139 USA

The use of multivariate classifiers, especially neural networks and decision trees, has become commonplace in particle physics. Typically, a series of classifiers is trained rather than just one to enhance the performance;this is known as boosting. This paper presents a novel method of boosting that produces a uniform selection efficiency in a selected multivariate space. Such a technique is well suited for amplitude analyses or other situations where optimizing a single integrated figure of merit is not what is desired.

关键词： Analysis and statistical methods data processing methods

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Riser Integrity Monitoring Techniques and data processing methods

Riser Integrity Monitoring Techniques and Data Processing Me...

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18th International Offshore and Polar Engineering Conference (ISOPE 2008)

作者： Maheshwari, Himanshu Ruf, Wolfgang Walters, Dave 2H Offshore Inc Houston TX USA

ISBN: (纸本)9781880653708

Riser integrity monitoring provides critical performance data during day to day operation and in extreme events. In-situ integrity monitoring improves the understanding of the complex riser behavior leading to enhancement of design practices. The paper discusses a range of methodologies for offshore riser monitoring. A review of existing and planned monitoring programs is provided with particular focus on the level of success achieved. Monitoring instrumentation and applications are discussed from the "fit for purpose" perspective, highlighting the monitoring objectives, reliability requirements and offshore operations. The paper also describes data processing methods used for screening and evaluating the collected data. The differences amongst standalone, hardwired, and acoustic data processing and further analysis of the monitoring data are discussed. Hardwired methods are focused on providing information that are relevant for making operational decisions at offshore facilities during day to day activities. Additional onshore data processing is focusing on providing information that can be used in the continuous effort to better understand riser response. In summary, the paper discusses the relative benefits and potential problems associated with hardwired, stand-alone and acoustic monitoring systems in adding value to the integrity management of deepwater risers.

关键词： Riser monitoring structural monitoring data processing methods

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Progresses in development of the ITER edge Thomson scattering system

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JOURNAL OF INSTRUMENTATION 2013年第12期8卷 C12001-C12001页

作者： Yatsuka, E. Bassan, M. Hatae, T. Ishikawa, M. Shimada, T. Vayakis, G. Walsh, M. Scannell, R. Huxford, R. Bilkova, P. Bohm, P. Aftanas, M. Itami, K. Japan Atom Energy Agcy Naka Ibaraki Japan ITER Org St Paul Les Durance France Culham Ctr Fus Energy Abingdon Oxon England RBH Opt Burgess Hill England Inst Plasma Phys AS CR Prague Czech Republic

This paper includes discussions of spatial resolution and accuracy of the edge Thomson scattering system in ITER (ITER ETS). In the present design, the dominant factor for spatial resolution degradation relative to the scattering length is aberrations of the collection optics. A scattering length of approximately 4 mm is acceptable to obtain a spatial resolution of 5 mm. Statistical errors were evaluated according to measurement accuracy. Since the background light during ITER plasma discharge is much stronger than the Thomson scattering, the laser pulse duration is one of the most crucial specifications to obtain accurate measurements. The impact of fast sampling relative to current integration was also investigated. It is expected that the measurement accuracy improves when the waveform of the scattered light is sampled directly particularly for low density measurement.

关键词： Plasma diagnostics - interferometry spectroscopy and imaging data processing methods

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Digital cavities and their potential applications

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JOURNAL OF INSTRUMENTATION 2013年第05期8卷 T05005-T05005页

作者： Karki, K. Torbjornsson, M. Widom, J. R. Marcus, A. H. Pullerits, T. Lund Univ S-22241 Lund Sweden Univ Oregon Eugene OR 97403 USA

The concept of a digital cavity is presented. The functionality of a tunable radio-frequency/microwave cavity with unrestricted Q-factor is implemented. The theoretical aspects of the cavity and its potential applications in high resolution spectroscopy and synchronization of clocks together with examples in signal processing and data acquisition are discussed.

关键词： data processing methods data acquisition concepts data reduction methods

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A multi-energy X-ray backscatter system for explosives detection

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JOURNAL OF INSTRUMENTATION 2013年第04期8卷 P04003-P04003页

作者： Paulus, C. Tabary, J. Pierron, N. Billon Dinten, J. -M. Fabiani, E. Mathy, F. Mougel, F. Rinkel, J. Verger, L. CEA LETI F-38054 Grenoble France

Most luggage inspection systems are based on X-ray transmission technologies, such as radiography and computed tomography. These techniques have limitations, especially with large or dense objects or objects which are placed close to a wall not allowing access to the rear side for radiography (for instance with abandoned luggage). Portable systems using backscattered X-rays could be an alternative solution when analyzing a suspicious object from one side only, without contact, particularly for homeland security applications. However, portable systems are not currently available. X-ray backscatter imaging, unlike X-ray radiography, reveals low Z materials such as explosives, which may be hidden inside luggage or behind a screen. Specific analysis of backscattered spectra can provide further information about the suspect material in the backscatter image. This can help discriminate between explosive and inert materials. In this article, we detail this discrimination process and the associated developed laboratory prototype. Experimental results are presented, demonstrating the system's performance.

关键词： Inspection with x-rays Detection of explosives data processing methods

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Noise reduction in muon tomography for detecting high density objects

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JOURNAL OF INSTRUMENTATION 2013年第12期8卷 P12007-P12007页

作者： Benettoni, M. Bettella, G. Bonomi, G. Calvagno, G. Calvini, P. Checchia, P. Cortelazzo, G. Cossutta, L. Donzella, A. Furlan, M. Gonella, F. Pegoraro, M. Garola, A. Rigoni Ronchese, P. Squarcia, S. Subieta, M. Vanini, S. Viesti, G. Zanuttigh, P. Zenoni, A. Zumerle, G. Ist Nazl Fis Nucl Sez Padova Padua Italy Univ Padua Dept Phys & Astron G Galilei Padua Italy Univ Brescia Dept Mech & Ind Engn Brescia Italy Ist Nazl Fis Nucl Sez Pavia I-27100 Pavia Italy Univ Padua Dept Informat Engn Padua Italy Univ Genoa Dept Phys Genoa Italy Ist Nazl Fis Nucl Sez Genova I-16146 Genoa Italy

The muon tomography technique, based on multiple Coulomb scattering of cosmic ray muons, has been proposed as a tool to detect the presence of high density objects inside closed volumes. In this paper a new and innovative method is presented to handle the density fluctuations (noise) of reconstructed images, a well known problem of this technique. The effectiveness of our method is evaluated using experimental data obtained with a muon tomography prototype located at the Legnaro National Laboratories (LNL) of the Istituto Nazionale di Fisica Nucleare (INFN). The results reported in this paper, obtained with real cosmic ray data, show that with appropriate image filtering and muon momentum classification, the muon tomography technique can detect high density materials, such as lead, albeit surrounded by light or medium density material, in short times. A comparison with algorithms published in literature is also presented.

关键词： data processing methods Wire chambers(MWPC, Thin-gap chambers, drift chambers, drift tubes, proportional chambers etc) Image reconstruction in medical imaging Detection of contraband and drugs

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