WorldWideScience

Sample records for avalanche detector based

  1. Measurement-based characterization of multipixel avalanche photodiodes for scintillating detectors

    CERN Document Server

    Dziewiecki, M

    2012-01-01

    Multipixel avalanche photodiodes (MAPD) are recently gaining popularity in high energy physics experiments as an attractive replacement for photomultiplier tubes, which have been extensively used for many years as a part of various scintillating detectors. Their low price, small dimensions and another features facilitating their use (like mechanical shock resistance, magnetic field immunity or moderate supply voltage) make the MAPDs a good choice for commercial use as well, what is reflected in growing number of producers as well as MAPD models available on the market. This dissertation presents Author’s experience with MAPD measurements and modelling, gained during his work on the T2K (Tokai-to-Kamioka) long-baseline neutrino experiment, carried out by an international collaboration in Japan. First, operation principle of the MAPD, definitions of various parameters and measurement methods are discussed. Then, a device for large-scale MAPD measurements and related data processing methods are described. Fina...

  2. Advances in Cryogenic Avalanche Detectors (review)

    CERN Document Server

    Buzulutskov, A

    2011-01-01

    Cryogenic Avalanche Detectors (CRADs) are referred to as a new class of noble-gas detectors operated at cryogenic temperatures with electron avalanching performed directly in the detection medium, the latter being in gaseous, liquid or two-phase (liquid-gas) state. Electron avalanching is provided by Micro-Pattern Gas Detector (MPGD) multipliers, in particular GEMs and THGEMs, operated at cryogenic temperatures in dense noble gases. The final goal for this kind of detectors is the development of large-volume detectors of ultimate sensitivity for rare-event experiments and medical applications, such as coherent neutrino-nucleus scattering, direct dark matter search, astrophysical (solar and supernova) neutrino detection experiments and Positron Emission Tomography technique. This review is the first attempt to summarize the results on CRAD performances obtained by different groups. A brief overview of the available CRAD concepts is also given and the most remarkable CRAD physics effects are discussed.

  3. Novel radiation detectors based on multi pixels avalanche photodiodes: their status and perspectives of application

    International Nuclear Information System (INIS)

    Full text: Different versions of silicon avalanche photodiodes (APD), as well as new multi pixel avalanche photodiodes (MAPD) have been discussed widely during the last decade as an advanced photon counter for various applications. The sensitive area of a MAPD contains a matrix of independent micro-pixels with individual passive elements, which are created on a common silicon wafer. The individual passive elements provide local suppression of the avalanche process and discharge each micro-pixel to a common conducting or metal electrode. The advanced properties of a MAPD are connected with a local negative feedback (LNF) effect, which result in a local self-suppression of the avalanche gain due to individual passive elements with necessary resistivity and capacitance and, consequently, significantly reduces the influence of crystal non-uniformities on the characteristics of the avalanche multiplication process. The LNF effect is achieved by forming a specific matrix in the multilayer silicon structure which ensures a localisation of the avalanche processes and limits them in frames of independent micro-regions of 3-50 m in size, depending of the MAPD design. Thus, the micro-pixel structure in a MAPD results in a unique combination of high signal amplification and uniform avalanche multiplication over the entire sensitive area of the device. Each pixel has a sandwich like structure like a metal-resistive layer-semiconductor (MRS). This device is made in a very simple technology and it may demonstrate very good parameters in the red and near infrared regions of spectrum.

  4. Gallium-based avalanche photodiode optical crosstalk

    Science.gov (United States)

    Blazej, Josef; Prochazka, Ivan; Hamal, Karel; Sopko, Bruno; Chren, Dominik

    2006-11-01

    Solid-state single photon detectors based on avalanche photodiode are getting more attention in various areas of applied physics: optical sensors, quantum key distribution, optical ranging and Lidar, time-resolved spectroscopy, X-ray laser diagnostics, and turbid media imaging. Avalanche photodiodes specifically designed for single photon counting semiconductor avalanche structures have been developed on the basis of various materials: Si, Ge, GaP, GaAsP, and InGaP/InGaAs at the Czech Technical University in Prague during the last 20 years. They have been tailored for numerous applications. Trends in demand are focused on detection array construction recently. Even extremely small arrays containing a few cells are of great importance for users. Electrical crosstalk between individual gating and quenching circuits and optical crosstalk between individual detecting cells are serious limitation for array design and performance. Optical crosstalk is caused by the parasitic light emission of the avalanche which accompanies the photon detection process. We have studied in detail the optical emission of the avalanche photon counting structure in the silicon- and gallium-based photodiodes. The timing properties and spectral distribution of the emitted light have been measured for different operating conditions to quantify optical crosstalk. We conclude that optical crosstalk is an inherent property of avalanche photodiode operated in Geiger mode. The only way to minimize optical crosstalk in avalanche photodiode array is to build active quenching circuit with minimum response time.

  5. TCAD simulation of Low Gain Avalanche Detectors

    Science.gov (United States)

    Dalal, Ranjeet; Jain, Geetika; Bhardwaj, Ashutosh; Ranjan, Kirti

    2016-11-01

    In the present work, detailed simulation using Technology Computer Aided Design (TCAD) tool, Silvaco for non-irradiated and irradiated LGAD (Low Gain Avalanche Detector) devices has been carried out. The effects of different design parameters and proton irradiation on LGAD operation are discussed in detail. An already published effective two trap bulk damage model is used to simulate the radiation damage without implementing any acceptor removal term. The TCAD simulation for irradiated LGAD devices produce decreasing gain with increasing fluence, similar to the measurement results. The space charge density and electric field distribution are used to illustrate the possible reasons for the degradation of gain of the irradiated LGAD devices.

  6. Avalanche photodiodes for the CMS detector

    CERN Document Server

    Deiters, K; Ingram, Q; Nicol, S; Musienko, I; Patel, B; Renker, D; Reucroft, S; Rusack, R W; Sakhelashvili, T M; Singovsky, A V; Swain, J D; Vikas, P

    2000-01-01

    The CERN LHC experiment CMS has selected for the readout of the barrel crystal calorimeter a 5*5 mm/sup 2/ avalanche photodiode (APD) manufactured by Hamamatsu Photonics. In the detector we will equip each crystal with two APDs for a total of 122400 diodes. As the calorimeter will be almost completely inaccessible during the life of the detector, the assurance that they will survive with a high probability in the intense radiation field is an essential part of the of the APD qualification process. In this paper the properties of the APD selected will be described, as well as the procedures we have developed to assure their radiation hardness and reliability. (2 refs).

  7. Miniaturized time-resolved Raman spectrometer for planetary science based on a fast single photon avalanche diode detector array.

    Science.gov (United States)

    Blacksberg, Jordana; Alerstam, Erik; Maruyama, Yuki; Cochrane, Corey J; Rossman, George R

    2016-02-01

    We present recent developments in time-resolved Raman spectroscopy instrumentation and measurement techniques for in situ planetary surface exploration, leading to improved performance and identification of minerals and organics. The time-resolved Raman spectrometer uses a 532 nm pulsed microchip laser source synchronized with a single photon avalanche diode array to achieve sub-nanosecond time resolution. This instrument can detect Raman spectral signatures from a wide variety of minerals and organics relevant to planetary science while eliminating pervasive background interference caused by fluorescence. We present an overview of the instrument design and operation and demonstrate high signal-to-noise ratio Raman spectra for several relevant samples of sulfates, clays, and polycyclic aromatic hydrocarbons. Finally, we present an instrument design suitable for operation on a rover or lander and discuss future directions that promise great advancement in capability.

  8. Single-Photon-Sensitive HgCdTe Avalanche Photodiode Detector

    Science.gov (United States)

    Huntington, Andrew

    2013-01-01

    The purpose of this program was to develop single-photon-sensitive short-wavelength infrared (SWIR) and mid-wavelength infrared (MWIR) avalanche photodiode (APD) receivers based on linear-mode HgCdTe APDs, for application by NASA in light detection and ranging (lidar) sensors. Linear-mode photon-counting APDs are desired for lidar because they have a shorter pixel dead time than Geiger APDs, and can detect sequential pulse returns from multiple objects that are closely spaced in range. Linear-mode APDs can also measure photon number, which Geiger APDs cannot, adding an extra dimension to lidar scene data for multi-photon returns. High-gain APDs with low multiplication noise are required for efficient linear-mode detection of single photons because of APD gain statistics -- a low-excess-noise APD will generate detectible current pulses from single photon input at a much higher rate of occurrence than will a noisy APD operated at the same average gain. MWIR and LWIR electron-avalanche HgCdTe APDs have been shown to operate in linear mode at high average avalanche gain (M > 1000) without excess multiplication noise (F = 1), and are therefore very good candidates for linear-mode photon counting. However, detectors fashioned from these narrow-bandgap alloys require aggressive cooling to control thermal dark current. Wider-bandgap SWIR HgCdTe APDs were investigated in this program as a strategy to reduce detector cooling requirements.

  9. Parallel plate avalanche detector PPAD construction and testing

    International Nuclear Information System (INIS)

    A multi-step two dimentsioned postion sensitive parallel plate avalanche detector (PPAD) was constructed locally to be later used in ion-atom collision experiments. The constructed detector was tested using a 1- 2.5 MeV He + beam, supplied from the University of Jordan Van de Graaff accelerator (JOVAC), under several grid voltages and detecting gas pressures (4 -10 mbar). A new data acquisition system MPDAS, interfaced with an ATARI-ST microcomputer was used during on-line measurements. The data were collected in List-mode so that they can be retrieved later in off-line mode analysis using LISA-ST program code. The 1-D and 2-D spectra reveal that good energy and position resolutions are obtaained at high pressures. The limstations on the postion resoulution are governed by the nonliearities of the W and S-anode and are explained to be due to partition noise arising from the fluctuation of the charge distribution falling on the anode. The energy spectra exhibit also energy peak shifts. The results are explained within the framework of ion-atom collisions processes and stopping effects. The data also suggest that some refinements are required to carry out ion-collision experiments to get a better understanding about the ion-atom interactions and its governing mechanisms.(author). 28 refs., 30 figs., 4 Tabs

  10. Development of new hole-type avalanche detectors and the first results of their applications

    CERN Document Server

    Charpak, Georges; Breuil, P.; Di Mauro, A.; Martinengo, P.; Peskov, V.

    2008-01-01

    We have developed a new detector of photons and charged particles- a hole-type structure with electrodes made of a double layered resistive material: a thin low resistive layer coated with a layer having a much higher resistivity. One of the unique features of this detector is its capability to operate at high gas gains (up to 10E4) in air or in gas mixtures with air. They can also operate in a cascaded mode or be combined with other detectors, for example with GEM. This opens new avenues in their applications. Several prototypes of these devices based on new detectors and oriented on practical applications were developed and successfully tested: a detector of soft X-rays and alpha particles, a flame sensor, a detector of dangerous gases. All of these detectors could operate stably even in humid air and/or in dusty conditions. The main advantages of these detectors are their simplicity, low cost and high sensitivity. For example, due to the avalanche multiplication, the detectors of flames and dangerous gases...

  11. High-Speed Radiation Tolerant Avalanche Photodiodes Based on InGaN for Space Altimeter Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — High-performance, radiation-tolerant detectors are required for the time-of-flight laser based rangefinders. Avalanche photodiodes (APDs) are conventionally chosen...

  12. HgCdTe e-avalanche photodiode detector arrays

    OpenAIRE

    Anand Singh; Shukla, A. K.; Ravinder Pal

    2015-01-01

    Initial results on the MWIR e-APD detector arrays with 30 μm pitch fabricated on LPE grown compositionally graded p-HgCdTe epilayers are presented. High dynamic resistance times active area (R0A) product 2 × 106 Ω-cm2, low dark current density 4 nA/cm2 and high gain 5500 at -8 V were achieved in the n+-υ-p+ HgCdTe e-APD at 80 K. LPE based HgCdTe e-APD development makes this technology amenable for adoption in the foundries established for the conventional HgCdTe photovoltaic detector arrays w...

  13. Radiation hard avalanche photodiodes for the CMS detector

    CERN Document Server

    Antunovic, Z; Deiters, K; Godinovic, N; Ingram, Q; Kuznetsov, A; Musienko, Y; Puljak, I; Renker, D; Reucroft, S; Rusack, R; Sakhelashvili, T M; Singovsky, A V; Soric, I; Swain, J

    2005-01-01

    The avalanche photodiodes, developed by Hamamatsu Photonics in collaboration with CMS, which are to be used to read out the lead tungstate crystals in the barrel part of the CMS electromagnetic calorimeter, are described. The procedures taken to ensure their long-term reliability in the radiation environment expected in CMS are outlined, as well as the studies made to verify the very high reliability required.

  14. Radiation Hard Avalanche Photo-Diodes for the CMS detector

    CERN Document Server

    Antunovic, Z; Deiters, K; Godinovic, N; Ingram, Q; Kuznetsov, A; Musienko, Y; Puljak, I; Reucroft, S; Rusack, R W; Sakhelashvili, T M; Singovsky, A V; Soric, I; Swain, J D

    2003-01-01

    The avalanche photo-diodes, developed by Hamamatsu Photonics in collaboration with CMS, which are to be used to read out the lead tungstate crystals in the barrel part of the CMS electromagnetic calorimeter, are described. The procedures taken to ensure their long term reliability in the radiation environment expected in CMS are outlined, as well as the studies made to verify the very high reliability required.

  15. Random Number Hardware Generator Using Geiger-Mode Avalanche Photo Detector

    CERN Document Server

    Beznosko, D; Duspayev, A; Tailakov, A; Yessenov, M

    2015-01-01

    This paper presents the physical concept and test results of sample data of the high-speed hardware true random number generator design based on typically used for High Energy Physics hardware. Main features of this concept are the high speed of the true random numbers generation (tens of Mbt/s), miniature size and estimated lower production cost. This allows the use of such a device not only in large companies and government offices but for the end-user data cryptography, in classrooms, in scientific Monte-Carlo simulations, computer games and any other place where large number of true random numbers is required. The physics of the operations principle of using a Geiger-mode avalanche photo detector is discussed and the high quality of the data collected is demonstrated.

  16. Design and TCAD simulation of double-sided pixelated low gain avalanche detectors

    Energy Technology Data Exchange (ETDEWEB)

    Dalla Betta, Gian-Franco, E-mail: gianfranco.dallabetta@unitn.it [Dipartimento di Ingegneria Industriale, Università di Trento, Via Sommarive 9, 38123 Trento (Italy); TIFPA INFN, Via Sommarive 14, 38123 Trento (Italy); Pancheri, Lucio [Dipartimento di Ingegneria Industriale, Università di Trento, Via Sommarive 9, 38123 Trento (Italy); TIFPA INFN, Via Sommarive 14, 38123 Trento (Italy); Boscardin, Maurizio [Fondazione Bruno Kessler, Via Sommarive 18, 38123 Trento (Italy); TIFPA INFN, Via Sommarive 14, 38123 Trento (Italy); Paternoster, Giovanni [Fondazione Bruno Kessler, Via Sommarive 18, 38123 Trento (Italy); Piemonte, Claudio [Fondazione Bruno Kessler, Via Sommarive 18, 38123 Trento (Italy); TIFPA INFN, Via Sommarive 14, 38123 Trento (Italy); Cartiglia, Nicolo; Cenna, Francesca [INFN Sezione di Torino, Via P. Giuria 2, 10125 Torino (Italy); Bruzzi, Mara [Dipartimento di FIsica e Astronomia, Università di Firenze, and INFN Sezione di Firenze, Via Giovanni Sansone 1, 50019 Sesto Fiorentino (Italy)

    2015-10-01

    We introduce a double-sided variant of low gain avalanche detector, suitable for pixel arrays without dead-area in between the different read-out elements. TCAD simulations were used to validate the device concept and predict its performance. Different design options and selected simulation results are presented, along with the proposed fabrication process.

  17. Eight-fold signal amplification of a superconducting nanowire single-photon detector using a multiple-avalanche architecture

    CERN Document Server

    Zhao, Qingyuan; Dane, Andrew; Najafi, Faraz; Bellei, Francesco; De Fazio, Domenico; Sunter, Kristen; Ivry, Yachin; Berggren, Karl K

    2014-01-01

    Superconducting nanowire avalanche single-photon detectors (SNAPs) with n parallel nanowires are advantageous over single-nanowire detectors because their output signal amplitude scales linearly with n. However, the SNAP architecture has not been viably demonstrated for n > 4. To increase n for larger signal amplification, we designed a multi-stage, successive-avalanche architecture which used nanowires, connected via choke inductors in a binary-tree layout. We demonstrated an avalanche detector with n = 8 parallel nanowires and achieved eight-fold signal amplification, with a timing jitter of 54 ps.

  18. A two-phase argon avalanche detector operated in a single electron counting mode

    OpenAIRE

    Bondar, A.(Budker Institute of Nuclear Physics (SB RAS), Novosibirsk State University, Novosibirsk, Russia); Buzulutskov, A.; Grebenuk, A.; Pavlyuchenko, D.; Snopkov, R.; Tikhonov, Y.; Kudryavtsev, V.A.; Lightfoot, P.K.; Spooner, N.J.C.

    2006-01-01

    The performance of a two-phase Ar avalanche detector in a single electron counting mode was studied, with regard to potential application in coherent neutrino-nucleus scattering and dark matter search experiments. The detector comprised of a 1 cm thick liquid Ar layer and a triple-GEM multiplier operated in the saturated vapour above the liquid phase. Successful operation of the detector in single electron counting mode, in the gain range from 6000 to 40000, has for the first time been demons...

  19. HgCdTe Infrared Avalanche Photodiode Single Photon Detector Arrays for the LIST and Other Decadal Missions Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Develop a HgCdTe avalanche photodiode (APD)  SWIR/IR linear mode photon counting (LMPC) array detector system in support of the LIST lidar. Provide a new type...

  20. A novel technique for the measurement of the avalanche fluctuation of gaseous detectors

    CERN Document Server

    Kobayashi, Makoto; Kawaguchi, Tomohiko; Fujii, Keisuke; Fusayasu, Takahiro; Ikematsu, Katsumasa; Kato, Yukihiro; Kawada, Shin-ichi; Matsuda, Takeshi; Settles, Ronald Dean; Sugiyama, Akira; Takahashi, Tohru; Tian, Junping; Watanabe, Takashi; Yonamine, Ryo

    2016-01-01

    We have developed a novel technique for the measurement of the avalanche fluctuation of gaseous detectors using a UV laser. The technique is simple and requires a short data-taking time of about ten minutes. Furthermore, it is applicable for relatively low gas gains. Our experimental setup as well as the measurement principle, and the results obtained with a stack of Gas Electron Multipliers (GEMs) operated in several gas mixtures are presented.

  1. Two-phase Cryogenic Avalanche Detector with electroluminescence gap operated in argon doped with nitrogen

    CERN Document Server

    Bondar, A; Dolgov, A; Nosov, V; Shekhtman, L; Shemyakina, E; Sokolov, A

    2016-01-01

    A two-phase Cryogenic Avalanche Detector (CRAD) with electroluminescence (EL) gap, operated in argon doped with a minor (49$\\pm$7 ppm) admixture of nitrogen, has been studied. The EL gap was optically read out using cryogenic PMTs located on the perimeter of the gap. We present the results of the measurements of the N$_2$ content, detector sensitivity to X-ray-induced signals, EL gap yield and electron lifetime in the liquid. The detector sensitivity, at a drift field in liquid Ar of 0.6 kV/cm, was measured to be 9 and 16 photoelectrons recorded at the PMTs per keV of deposited energy at 23 and 88 keV respectively. Such two-phase detectors, with enhanced sensitivity to the S2 (ionization-induced) signal, are relevant in the field of argon detectors for dark matter search and low energy neutrino detection.

  2. Quick single-photon detector with many avalanche photo diodes working on the time division

    Institute of Scientific and Technical Information of China (English)

    Jian Peng; Yifei Fu; Li Yao; Xudong Shang; Zhixin Lu; Bojun Yang; Li Yu

    2008-01-01

    Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.

  3. First results of the two-phase argon avalanche detector performance with CsI photocathode

    OpenAIRE

    Bondar, A.(Budker Institute of Nuclear Physics (SB RAS), Novosibirsk State University, Novosibirsk, Russia); Buzulutskov, A.; Grebenuk, A.; Pavlyuchenko, D.; Snopkov, R.; Tikhonov, Y.

    2007-01-01

    The performance of a two-phase Ar avalanche detector with CsI photocathode was studied, with regard to potential application in coherent neutrino-nucleus scattering and dark matter search experiments. The detector comprised a 1 cm thick liquid Ar layer and a triple-GEM multiplier operated in the saturated vapor above the liquid phase; the CsI photocathode was deposited on the first GEM. Successful detection of both primary scintillation and ionization signals, produced by beta-particles in li...

  4. Single photon avalanche detectors: prospects of new quenching and gain mechanisms

    Directory of Open Access Journals (Sweden)

    Hall David

    2015-11-01

    Full Text Available While silicon single-photon avalanche diodes (SPAD have reached very high detection efficiency and timing resolution, their use in fibre-optic communications, optical free space communications, and infrared sensing and imaging remains limited. III-V compounds including InGaAs and InP are the prevalent materials for 1550 nm light detection. However, even the most sensitive 1550 nm photoreceivers in optical communication have a sensitivity limit of a few hundred photons. Today, the only viable approach to achieve single-photon sensitivity at 1550 nm wavelength from semiconductor devices is to operate the avalanche detectors in Geiger mode, essentially trading dynamic range and speed for sensitivity. As material properties limit the performance of Ge and III-V detectors, new conceptual insight with regard to novel quenching and gain mechanisms could potentially address the performance limitations of III-V SPADs. Novel designs that utilise internal self-quenching and negative feedback can be used to harness the sensitivity of single-photon detectors,while drastically reducing the device complexity and increasing the level of integration. Incorporation of multiple gain mechanisms, together with self-quenching and built-in negative feedback, into a single device also hold promise for a new type of detector with single-photon sensitivity and large dynamic range.

  5. Single photon avalanche detectors: prospects of new quenching and gain mechanisms

    Science.gov (United States)

    Hall, David; Liu, Yu-Hsin; Lo, Yu-Hwa

    2015-11-01

    While silicon single-photon avalanche diodes (SPAD) have reached very high detection efficiency and timing resolution, their use in fibre-optic communications, optical free space communications, and infrared sensing and imaging remains limited. III-V compounds including InGaAs and InP are the prevalent materials for 1550 nm light detection. However, even the most sensitive 1550 nm photoreceivers in optical communication have a sensitivity limit of a few hundred photons. Today, the only viable approach to achieve single-photon sensitivity at 1550 nm wavelength from semiconductor devices is to operate the avalanche detectors in Geiger mode, essentially trading dynamic range and speed for sensitivity. As material properties limit the performance of Ge and III-V detectors, new conceptual insight with regard to novel quenching and gain mechanisms could potentially address the performance limitations of III-V SPADs. Novel designs that utilise internal self-quenching and negative feedback can be used to harness the sensitivity of single-photon detectors,while drastically reducing the device complexity and increasing the level of integration. Incorporation of multiple gain mechanisms, together with self-quenching and built-in negative feedback, into a single device also hold promise for a new type of detector with single-photon sensitivity and large dynamic range.

  6. Improving the performance of the MWPC X-ray imaging detector by means of the multi-step avalanche technique

    International Nuclear Information System (INIS)

    X-ray imaging systems based on conventional MWPC technology and artificial delay line readout techniques have been developed at RAL for several applications over a period of some eight years. Successful as this effort has been, it is now perceived that very limited scope exists for the further improvement of the imaging capability of the standard MWPC design. Attention has therefore been turned to the possibility of exploiting the multi-step avalanche (MSA) system of electron multiplication in this context. Results from a prototype system are presented which show spatial resolution better than that achieved in our MWPC systems with no wire artefacts in the image. The facility for controlling the effective depth of the detector electronically is also demonstrated so offering some alleviation of the parallax problem common to all gaseous X-ray detectors. (orig.)

  7. Design and fabrication of an optimum peripheral region for low gain avalanche detectors

    Science.gov (United States)

    Fernández-Martínez, Pablo; Flores, D.; Hidalgo, S.; Greco, V.; Merlos, A.; Pellegrini, G.; Quirion, D.

    2016-06-01

    Low Gain Avalanche Detectors (LGAD) represent a remarkable advance in high energy particle detection, since they provide a moderate increase (gain ~10) of the collected charge, thus leading to a notable improvement of the signal-to-noise ratio, which largely extends the possible application of Silicon detectors beyond their present working field. The optimum detection performance requires a careful implementation of the multiplication junction, in order to obtain the desired gain on the read out signal, but also a proper design of the edge termination and the peripheral region, which prevents the LGAD detectors from premature breakdown and large leakage current. This work deals with the critical technological aspects required to optimize the LGAD structure. The impact of several design strategies for the device periphery is evaluated with the aid of TCAD simulations, and compared with the experimental results obtained from the first LGAD prototypes fabricated at the IMB-CNM clean room. Solutions for the peripheral region improvement are also provided.

  8. Design and Fabrication of an Optimum Peripheral Region for Low Gain Avalanche Detectors

    CERN Document Server

    Fernandez-Martinez, Pablo; Hidalgo, Salvador; Greco, Virginia; Merlos, Angel; Pellegrini, Giulio; Quirion, David

    2015-01-01

    Low Gain Avalanche Detectors (LGAD) represent a remarkable advance in high energy particle detection, since they provide a moderate increase (gain ~10) of the collected charge, thus leading to a notable improvement of the signal-to-noise ratio, which largely extends the possible application of Silicon detectors beyond their present working field. The optimum detection performance requires a careful implementation of the multiplication junction, in order to obtain the desired gain on the read out signal, but also a proper design of the edge termination and the peripheral region, which prevents the LGAD detectors from premature breakdown and large leakage current. This work deals with the critical technological aspects when optimising the LGAD structure. The impact of several design strategies for the device periphery is evaluated with the aid of TCAD simulations, and compared with the experimental results obtained from the first LGAD prototypes fabricated at the IMB-CNM clean room. Solutions for the peripheral...

  9. Thick GEM versus thin GEM in two-phase argon avalanche detectors

    CERN Document Server

    Bondar, A; Grebenuk, A; Pavlyuchenko, D; Tikhonov, Y; Breskin, Amos

    2008-01-01

    The performance of thick GEMs (THGEMs) was compared to that of thin GEMs in two-phase Ar avalanche detectors, in view of their potential application in coherent neutrino-nucleus scattering, dark-matter search and in other rare-event experiments. The detectors comprised a 1 cm thick liquid-Ar layer followed by either a double-THGEM or a triple-GEM multiplier, operated in the saturated vapor above the liquid phase. Three types of THGEMs were studied: those made of G10 and Kevlar and that with resistive electrodes (RETHGEM). Only the G10-made THGEM showed a stable performance in two-phase Ar with gains reaching 3000. Successful operation of two-phase Ar avalanche detectors with either thin- or thick-GEM multipliers was demonstrated at low detection thresholds, of 4 and 20 primary electrons respectively. Compared to the triple-GEM the double-THGEM multiplier yielded slower anode signals; this allowed applying a pulse-shape analysis to effectively reject noise signals. Noise rates of both multipliers were evaluate...

  10. High speed quantitative digital beta autoradiography using a multistep avalanche detector and an Apple II microcomputer

    International Nuclear Information System (INIS)

    The development of an electronic, digital beta autoradiography system is described. Using a multistep avalanche/multiwire proportional counter (MSA/MWPC) detector system fitted with delay line readout, high speed digital imaging is demonstrated with submillimeter spatial resolution. In the case of autoradiography with a tritium label, image acquisition requires about one hour compared with several weeks for conventional film techniques. Good proportionality of observed counting rate relative to the known tritium activity is demonstrated. The application of the system to autoradiography in immunoelectrophoresis, histopathology and DNA sequencing is described (using 125I, 14C and 35S labels in addition to 3H). (orig.)

  11. Assessing risk based on uncertain avalanche activity patterns

    Science.gov (United States)

    Zeidler, Antonia; Fromm, Reinhard

    2015-04-01

    Avalanches may affect critical infrastructure and may cause great economic losses. The planning horizon of infrastructures, e.g. hydropower generation facilities, reaches well into the future. Based on the results of previous studies on the effect of changing meteorological parameters (precipitation, temperature) and the effect on avalanche activity we assume that there will be a change of the risk pattern in future. The decision makers need to understand what the future might bring to best formulate their mitigation strategies. Therefore, we explore a commercial risk software to calculate risk for the coming years that might help in decision processes. The software @risk, is known to many larger companies, and therefore we explore its capabilities to include avalanche risk simulations in order to guarantee a comparability of different risks. In a first step, we develop a model for a hydropower generation facility that reflects the problem of changing avalanche activity patterns in future by selecting relevant input parameters and assigning likely probability distributions. The uncertain input variables include the probability of avalanches affecting an object, the vulnerability of an object, the expected costs for repairing the object and the expected cost due to interruption. The crux is to find the distribution that best represents the input variables under changing meteorological conditions. Our focus is on including the uncertain probability of avalanches based on the analysis of past avalanche data and expert knowledge. In order to explore different likely outcomes we base the analysis on three different climate scenarios (likely, worst case, baseline). For some variables, it is possible to fit a distribution to historical data, whereas in cases where the past dataset is insufficient or not available the software allows to select from over 30 different distribution types. The Monte Carlo simulation uses the probability distribution of uncertain variables

  12. A cooled avalanche photodiode detector for X-ray magnetic diffraction experiments

    CERN Document Server

    Kishimoto, S; Ito, M

    2001-01-01

    A cooled avalanche photodiode (APD) detector was developed for X-ray magnetic diffraction experiments. A stack of four silicon APDs was cooled down to 243 K by a thermoelectric cooler. The energy widths of 0.89 and 1.55 keV (FWHM) were obtained for 8.05 keV X-rays at 1x10 sup 6 s sup - sup 1 and for 16.53 keV X-rays at 2x10 sup 6 s sup - sup 1 , respectively. Test measurements of X-ray magnetic diffraction were executed using a terbium single crystal and white synchrotron radiation. A peak width of (1 0 3) reflection (5.4 keV) was roughly three times wider than that with a high-purity germanium detector.

  13. High-speed bridge circuit for InGaAs avalanche photodiode single-photon detector

    Science.gov (United States)

    Hashimoto, Hirofumi; Tomita, Akihisa; Okamoto, Atsushi

    2014-02-01

    Because of low power consumption and small footprint, avalanche photodiodes (APD) have been commonly applied to photon detection. Recently, high speed quantum communication has been demonstrated for high bit-rate quantum key distribution. For the high speed quantum communication, photon detectors should operate at GHz-clock frequencies. We propose balanced detection circuits for GHz-clock operation of InGaAs-APD photon detectors. The balanced single photon detector operates with sinusoidal wave gating. The sinusoidal wave appearing in the output is removed by the subtraction from APD signal without sharp band-elimination filters. Omission of the sharp filters removes the constraint on the operating frequency of the single photon detector. We present two designs, one works with two identical APDs, the other with one APD and a low-pass filter. The sinusoidal gating enables to eliminate the gating noise even with the simple configuration of the latter design. We demonstrated the balanced single photon detector operating with 1.020GHz clock at 233 K, 193 K, and 186.5 K. The dark count probability was 4.0 x 10-4 counts/pulse with the quantum efficiency of 10% at 233K, and 1.6 x 10-4 counts/pulse at 186.5 K. These results were obtained with easily available APDs (NR8300FP-C.C, RENESASS) originally developed for optical time-domain reflectmeters.

  14. SWAD: inherent photon counting performance of amorphous selenium multi-well avalanche detector

    Science.gov (United States)

    Stavro, Jann; Goldan, Amir H.; Zhao, Wei

    2016-03-01

    Photon counting detectors (PCDs) have the potential to improve x-ray imaging, however they are still hindered by several performance limitations and high production cost. By using amorphous Selenium (a-Se) the cost of PCDs can be significantly reduced compared to crystalline materials and enable large area detector fabrication. To overcome the problem of low carrier mobility and low charge conversion gain in a-Se, we are developing a novel direct conversion a- Se field-Shaping multi-Well Avalanche Detector (SWAD). SWAD circumvents the charge transport limitation by using a Frisch grid built within the readout circuit, reducing charge collection time to ~200 ns. Field shaping permits depth independent avalanche gain in wells, resulting in total conversion gain that is comparable to Si and CdTe. In the present work we investigate the effects of charge sharing and energy loss to understand the inherent photon counting performance for SWAD at x-ray energies used in breast imaging applications (20-50keV). The energy deposition profile for each interacting x-ray was determined with Monte Carlo simulation. For the energy ranges we are interested in, photoelectric interaction dominates, with a k-fluorescence yield of approximately 60%. Using a monoenergetic 45 keV beam incident on a target pixel in 400um of a-Se, our results show that only 20.42 % and 22.4 % of primary interacting photons have kfluorescence emissions which escape the target pixel for 100um and 85um pixel sizes respectively, demonstrating SWAD's potential for high spatial resolution applications.

  15. Avalanche photodiode based time-of-flight mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Ogasawara, Keiichi, E-mail: kogasawara@swri.edu; Livi, Stefano A.; Desai, Mihir I.; Ebert, Robert W.; McComas, David J.; Walther, Brandon C. [Southwest Research Institute, 6220 Culebra Road, San Antonio, Texas 78238 (United States)

    2015-08-15

    This study reports on the performance of Avalanche Photodiodes (APDs) as a timing detector for ion Time-of-Flight (TOF) mass spectroscopy. We found that the fast signal carrier speed in a reach-through type APD enables an extremely short timescale response with a mass or energy independent <2 ns rise time for <200 keV ions (1−40 AMU) under proper bias voltage operations. When combined with a microchannel plate to detect start electron signals from an ultra-thin carbon foil, the APD comprises a novel TOF system that successfully operates with a <0.8 ns intrinsic timing resolution even using commercial off-the-shelf constant-fraction discriminators. By replacing conventional total-energy detectors in the TOF-Energy system, APDs offer significant power and mass savings or an anti-coincidence background rejection capability in future space instrumentation.

  16. Negative feedback avalanche diode

    Science.gov (United States)

    Itzler, Mark Allen (Inventor)

    2010-01-01

    A single-photon avalanche detector is disclosed that is operable at wavelengths greater than 1000 nm and at operating speeds greater than 10 MHz. The single-photon avalanche detector comprises a thin-film resistor and avalanche photodiode that are monolithically integrated such that little or no additional capacitance is associated with the addition of the resistor.

  17. MPPC versus MRS APD in two-phase Cryogenic Avalanche Detectors

    International Nuclear Information System (INIS)

    Two-phase Cryogenic Avalanche Detectors (CRADs) with combined THGEM/GAPD multiplier have become an emerging potential technique for dark matter search and coherent neutrino-nucleus scattering experiments. In such a multiplier the THGEM hole avalanches are optically recorded in the Near Infrared (NIR) using a matrix of Geiger-mode APDs (GAPDs). To select the proper sensor, the performances of six GAPD types manufactured by different companies, namely by Hamamatsu (MPPCs), CPTA (MRS APDs) and SensL (SiPMs), have been comparatively studied at cryogenic temperatures when operated in two-phase CRADs in Ar at 87 K. While the GAPDs with ceramic packages failed to operate properly at cryogenic temperatures, those with plastic packages, namely MPPC S10931-100P and MRS APD 149-35, showed satisfactory performances at 87 K. In addition, MPPC S10931-100P turned out to be superior in terms of the higher detection efficiency, lower noise rate, lower pixel quenching resistor and better characteristics reproducibility

  18. MPPC versus MRS APD in two-phase Cryogenic Avalanche Detectors

    CERN Document Server

    Bondar, A; Dolgov, A; Shemyakina, E; Sokolov, A

    2015-01-01

    Two-phase Cryogenic Avalanche Detectors (CRADs) with combined THGEM/GAPD multiplier have become an emerging potential technique for dark matter search and coherent neutrino-nucleus scattering experiments. In such a multiplier the THGEM hole avalanches are optically recorded in the Near Infrared (NIR) using a matrix of Geiger-mode APDs (GAPDs). To select the proper sensor, the performances of six GAPD types manufactured by different companies, namely by Hamamatsu (MPPCs), CPTA (MRS APDs) and SensL (SiPMs), have been comparatively studied at cryogenic temperatures when operated in two-phase CRADs in Ar at 87 K. While the GAPDs with ceramic packages failed to operate properly at cryogenic temperatures, those with plastic packages, namely MPPC S10931-100P and MRS APD 149-35, showed satisfactory performances at 87 K. In addition, MPPC S10931-100P turned out to be superior in terms of the higher detection efficiency, lower nose rate, lower pixel quenching resistor and better characteristics reproducibility.

  19. First demonstration of THGEM/GAPD-matrix optical readout in two-phase Cryogenic Avalanche Detector in Ar

    CERN Document Server

    Bondar, A; Dolgov, A; Grebenuk, A; Shemyakina, E; Sokolov, A; Breskin, A; Thers, D

    2013-01-01

    The multi-channel optical readout of a THGEM multiplier coupled to a matrix of 3x3 Geiger-mode APDs (GAPDs) was demonstrated in a two-phase Cryogenic Avalanche Detector (CRAD) in Ar. The GAPDs recorded THGEM-hole avalanches in the Near Infrared (NIR). At an avalanche charge gain of 160, the yield of the combined THGEM/GAPD-matrix multiplier amounted at ~80 photoelectrons per 20 keV X-ray absorbed in the liquid phase. A spatial resolution of 2.5 mm (FWHM) has been measured for the impinging X-rays. This technique has potential applications in coherent neutrino-nucleus scattering and dark matter search experiments.

  20. Non-Geiger-Mode Single-Photon Avalanche Detector with Low Excess Noise

    Science.gov (United States)

    Zhao, Kai; Lo, YuHwa; Farr, William

    2010-01-01

    This design constitutes a self-resetting (gain quenching), room-temperature operational semiconductor single-photon-sensitive detector that is sensitive to telecommunications optical wavelengths and is scalable to large areas (millimeter diameter) with high bandwidth and efficiencies. The device can detect single photons at a 1,550-nm wavelength at a gain of 1 x 10(exp 6). Unlike conventional single photon avalanche detectors (SPADs), where gain is an extremely sensitive function to the bias voltage, the multiplication gain of this device is stable at 1 x 10(exp 6) over a wide range of bias from 30.2 to 30.9 V. Here, the multiplication gain is defined as the total number of charge carriers contained in one output pulse that is triggered by the absorption of a single photon. The statistics of magnitude of output signals also shows that the device has a very narrow pulse height distribution, which demonstrates a greatly suppressed gain fluctuation. From the histograms of both pulse height and pulse charge, the equivalent gain variance (excess noise) is between 1.001 and 1.007 at a gain of 1 x 10(exp 6). With these advantages, the device holds promise to function as a PMT-like photon counter at a 1,550- nm wavelength. The epitaxial layer structure of the device allows photons to be absorbed in the InGaAs layer, generating electron/hole (e-h) pairs. Driven by an electrical field in InGaAs, electrons are collected at the anode while holes reach the multiplication region (InAlAs p-i-n structure) and trigger the avalanche process. As a result, a large number of e-h pairs are created, and the holes move toward the cathode. Holes created by the avalanche process gain large kinetic energy through the electric field, and are considered hot. These hot holes are cooled as they travel across a p -InAlAs low field region, and are eventually blocked by energy barriers formed by the InGaAsP/ InAlAs heterojunctions. The composition of the InGaAsP alloy was chosen to have an 80 me

  1. Avalanche Debris Detection Using Satellite- and Drone Based Radar and Optical Remote Sensing

    Science.gov (United States)

    Eckerstorfer, M.; Malnes, E.; Vickers, H.; Solbø, S. A.; Tøllefsen, A.

    2014-12-01

    The mountainous fjord landscape in the county of Troms, around its capital Tromsø in Northern Norway is prone to high avalanche activity during the snow season. Large avalanches pose a hazard to infrastructure, such as buildings and roads, located between the steep mountainsides and the fjords. A prolonged cold spell during January and February 2014 was followed by rapid new-snow loading during March 2014, inducing a significant avalanche cycle with many spontaneous, size D4 avalanches that affected major transport veins. During and shortly after the avalanche cycle of March 2014, we obtained 11 Radarsat-2 Ultrafine mode scenes, chosen according to reported avalanche activity. We further collected four Radarsat-2 ScanSAR mode scenes and two Landsat-8 scenes covering the entire county of Troms. For one particular avalanche, we obtained a drone-based orthophoto, from which a DEM of the avalanche debris surface was derived, using structure-from-motion photogrammetry. This enabled us to calculate the debris volume accurately. We detected avalanche debris in the radar images visually, by applying two detection algorithms that make use of the increased backscatter in avalanche debris. This backscatter increase is a product of increased snow water equivalent and surface roughness, roughly of the order of 3 dB. In addition, we applied a multi-temporal approach by repeatedly detecting avalanche debris at different acquisition times, as well as a multi-sensor approach, covering similar areas with different sensors. This multi-temporal and multi-sensor approach enabled us to map the spatial extent and magnitude of the March 2014 avalanche cycle in the county Troms. With ESA's Sentinel-1 satellite, providing high-resolution, large swath radar images with a short repeat cycle, a complete avalanche record for a forecasting region could become feasible. In this first test season, we detected more than 550 avalanches that were released during a one-month period over an area of

  2. A new web-based system to improve the monitoring of snow avalanche hazard in France

    Science.gov (United States)

    Bourova, Ekaterina; Maldonado, Eric; Leroy, Jean-Baptiste; Alouani, Rachid; Eckert, Nicolas; Bonnefoy-Demongeot, Mylene; Deschatres, Michael

    2016-05-01

    Snow avalanche data in the French Alps and Pyrenees have been recorded for more than 100 years in several databases. The increasing amount of observed data required a more integrative and automated service. Here we report the comprehensive web-based Snow Avalanche Information System newly developed to this end for three important data sets: an avalanche chronicle (Enquête Permanente sur les Avalanches, EPA), an avalanche map (Carte de Localisation des Phénomènes d'Avalanche, CLPA) and a compilation of hazard and vulnerability data recorded on selected paths endangering human settlements (Sites Habités Sensibles aux Avalanches, SSA). These data sets are now integrated into a common database, enabling full interoperability between all different types of snow avalanche records: digitized geographic data, avalanche descriptive parameters, eyewitness reports, photographs, hazard and risk levels, etc. The new information system is implemented through modular components using Java-based web technologies with Spring and Hibernate frameworks. It automates the manual data entry and improves the process of information collection and sharing, enhancing user experience and data quality, and offering new outlooks to explore and exploit the huge amount of snow avalanche data available for fundamental research and more applied risk assessment.

  3. High speed quantitative digital beta autoradiography using a multi-step avalanche detector and an Apple-II microcomputer

    International Nuclear Information System (INIS)

    The development of an electronic, digital beta autoradiography system is described. Using a Multi-Step Avalanche/Multi-Wire Proportional Counter (MSA/MWPC) detector system fitted with delay line readout, high speed digital imaging is demonstrated with sub-millimeter spatial resolution. Good proportionality of observed counting rate relative to the known tritium activity is demonstrated. The application of the system to autoradiography in immunoelectrophoresis, histopathology and DNA sequencing is described. (author)

  4. Characterization of photo-multiplier tubes for the Cryogenic Avalanche Detector

    CERN Document Server

    Bondar, A; Dolgov, A; Nosov, V; Shekhtman, L; Sokolov, A

    2015-01-01

    New Cryogenic Avalanche Detector (CRAD) with ultimate sensitivity, that will be able to detect one primary electron released in the cryogenic liquid, is under development in the Laboratory of Cosmology and Particle Physics of the Novosibirsk State University jointly with the Budker Institute of Nuclear Physics. The CRAD will use two sets of cryogenic PMTs in order to get trigger signal either from primary scintillations in liquid Ar or from secondary scintillations in high field gap above the liquid. Two types of cryogenic PMTs produced by Hamamatsu Photonics were tested and the results are presented in this paper. Low background 3 inch PMT R11065- 10 demonstrated excellent performance according to its specifications provided by the producer. The gain measured with single electron response (SER) in liquid Ar reached 10^7, dark count rate rate did not exceed 300 Hz and pulse height resolution of single electron signals was close to 50%(FWHM). However, two R11065-10 PMTs out of 7 tested stopped functioning afte...

  5. Study on the realization of a minimum ionizing particle detector: development of a PPAC (Parallel-plate Avalanche Chamber)

    International Nuclear Information System (INIS)

    Parallel-Plate Avalanche Chamber (PPAC) detectors are used currently to observe nuclear disintegrations in nuclear physics. The work that has been done here shows PPAC can be used in high energy physics under certain conditions to detect minimum ionizing particles. Their advantage is to join good time resolution with low matter density. A PPAC prototype has been made with 90% efficiency, 3 NS jitter, 2 NS rise time, 20 mg/cm2 mass, 1.5 mm spatial accuracy. The parameters studied were electrodes design, choice of gas filling, electronics and anode strips. The detector is to be used as a hodoscope with high flux of particles

  6. Radiation hardness investigation of avalanche photodiodes for the Projectile Spectator Detector readout at the Compressed Baryonic Matter experiment

    International Nuclear Information System (INIS)

    In this paper, we discuss results of avalanche photodiodes radiation tests for Projectile Spectator Detector at future Compressed Baryonic Matter experiment. The tests were carried out in Nuclear Physics Institute of ASCR in Řež using the cyclotron facility. Secondary neutron beam was used for irradiation because the main radiation damage in the Projectile Spectator Detector is caused by neutrons. Two types of the avalanche photodiodes from Zecotek and Ketek manufacturers were investigated. Special attention was given to the noise investigation and self-annealing after the irradiation. We have irradiated two Ketek PM3375 diodes with equivalent dose for 1 MeV neutrons equal to 2.5±0.2×1012 n/cm2, and single Zecotek MAPD-3N diode with equivalent dose for 1 MeV neutrons equal to 3.4±0.2×1012 n/cm2. All the types of the diodes have shown an increasing level of the noise after the irradiation. From that we can conclude that those avalanche photodiodes are not able to detect single photons anymore due to high noise levels

  7. A new modeling and simulation method for important statistical performance prediction of single photon avalanche diode detectors

    Science.gov (United States)

    Xu, Yue; Xiang, Ping; Xie, Xiaopeng; Huang, Yang

    2016-06-01

    This paper presents a new modeling and simulation method to predict the important statistical performance of single photon avalanche diode (SPAD) detectors, including photon detection efficiency (PDE), dark count rate (DCR) and afterpulsing probability (AP). Three local electric field models are derived for the PDE, DCR and AP calculations, which show analytical dependence of key parameters such as avalanche triggering probability, impact ionization rate and electric field distributions that can be directly obtained from Geiger mode Technology Computer Aided Design (TCAD) simulation. The model calculation results are proven to be in good agreement with the reported experimental data in the open literature, suggesting that the proposed modeling and simulation method is very suitable for the prediction of SPAD statistical performance.

  8. High voltage short plus generation based on avalanche circuit

    International Nuclear Information System (INIS)

    Simulate the avalanche circuit in series with PSPICE module, design the high voltage short plus generation circuit by avalanche transistor in series for the sweep deflection circuit of streak camera. The output voltage ranges 1.2 KV into 50 ohm load. The rise time of the circuit is less than 3 ns. (authors)

  9. Single Photon Sensitive HgCdTe Avalanche Photodiode Detector (APD) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A linear mode HgCdT electron-initiated avalanche photodiode (EAPD) capable of 1570nm photon detection efficiency (PDE) at >10 MHz will be developed. The Phase I...

  10. Development of a 144-channel Hybrid Avalanche Photo-Detector for Belle II ring-imaging Cherenkov counter with an aerogel radiator

    Energy Technology Data Exchange (ETDEWEB)

    Nishida, S., E-mail: shohei.nishida@kek.jp [High Energy Accelerator Research Organization (KEK), Tsukuba (Japan); Adachi, I. [High Energy Accelerator Research Organization (KEK), Tsukuba (Japan); Hamada, N. [Toho University, Funabashi (Japan); Hara, K. [High Energy Accelerator Research Organization (KEK), Tsukuba (Japan); Iijima, T. [Nagoya University, Nagoya (Japan); Iwata, S.; Kakuno, H. [Tokyo Metropolitan University, Hachioji (Japan); Kawai, H. [Chiba University, Chiba (Japan); Korpar, S.; Krizan, P. [Jozef Stefan Institute, Ljubljana (Slovenia); Ogawa, S. [Toho University, Funabashi (Japan); Pestotnik, R.; Ŝantelj, L.; Seljak, A. [Jozef Stefan Institute, Ljubljana (Slovenia); Sumiyoshi, T. [Tokyo Metropolitan University, Hachioji (Japan); Tabata, M. [Chiba University, Chiba (Japan); Tahirovic, E. [Jozef Stefan Institute, Ljubljana (Slovenia); Yoshida, K. [Tokyo Metropolitan University, Hachioji (Japan); Yusa, Y. [Niigata University, Niigata (Japan)

    2015-07-01

    The Belle II detector, a follow up of the very successful Belle experiment, is under construction at the SuperKEKB electron–positron collider at KEK in Japan. For the PID system in the forward region of the spectrometer, a proximity-focusing ring-imaging Cherenkov counter with an aerogel radiator is being developed. For the position sensitive photon sensor, a 144-channel Hybrid Avalanche Photo-Detector has been developed with Hamamatsu Photonics K.K. In this report, we describe the specification of the Hybrid Avalanche Photo-Detector and the status of the mass production.

  11. Development of a 144-channel Hybrid Avalanche Photo-Detector for Belle II ring-imaging Cherenkov counter with an aerogel radiator

    International Nuclear Information System (INIS)

    The Belle II detector, a follow up of the very successful Belle experiment, is under construction at the SuperKEKB electron–positron collider at KEK in Japan. For the PID system in the forward region of the spectrometer, a proximity-focusing ring-imaging Cherenkov counter with an aerogel radiator is being developed. For the position sensitive photon sensor, a 144-channel Hybrid Avalanche Photo-Detector has been developed with Hamamatsu Photonics K.K. In this report, we describe the specification of the Hybrid Avalanche Photo-Detector and the status of the mass production

  12. Two examples of expert knowledge based system for avalanche forecasting and protection

    Science.gov (United States)

    Buisson, Laurent; Giraud, Gérald

    1995-11-01

    In avalanche modelling and control and in avalanche forecasting, most of the knowledge is based on scientific theory but the experience of specialists (field practitioners, forecasters...) plays a large role. This paper presents two French computer-based systems dedicated to avalanche modelling and control and to avalanche forecasting. They are both based on expert knowledge. ELSA (Etude et Limites de Sites d'Avalanches), is a computer system dedicated to the modelling of the knowledge of avalanche experts and to the integration of new symbolic computer models with classical numerical models. The basic aim of integration is to build a unique computer system incorporating all these models. After a description of the terrain representation, we present the different scenarios that ELSA takes into account. Then, the methods which deal with some phenomena occurring in avalanches are described. The problems involved in the integration of these methods close this first part. MEPRA is an expert system built to create an objective tool in avalanche risk forecasting. This development allowed us to imagine a processing system for 2 of the most important problems in avalanche risk forecasting: representation of the present snow cover characteristics and evaluation of avalanche instability and risk. In this way, mechanics and thermodynamics play a major role in the system. After a punctual validation at the location of a snow weather station and in order to describe the great variability of the snow pack and the avalanche risk in a massif, the MEPRA expert system was connected with a meteorological analysis system, SAFRAN and a numerical model to simulate the snow cover CROCUS. Then, every day, a MEPRA expert analysis is carried out in different locations with different orientations, slopes and altitudes. Its results were used successfully during the Winter Olympic Games of Albertville and by avalanche forecasters during the 92/93 winter season. The daily avalanche risks

  13. Assessing wet snow avalanche activity using detailed physics based snowpack simulations

    Science.gov (United States)

    Wever, N.; Vera Valero, C.; Fierz, C.

    2016-06-01

    Water accumulating on microstructural transitions inside a snowpack is often considered a prerequisite for wet snow avalanches. Recent advances in numerical snowpack modeling allow for an explicit simulation of this process. We analyze detailed snowpack simulations driven by meteorological stations in three different climate regimes (Alps, Central Andes, and Pyrenees), with accompanying wet snow avalanche activity observations. Predicting wet snow avalanche activity based on whether modeled water accumulations inside the snowpack locally exceed 5-6% volumetric liquid water content is providing a higher prediction skill than using thresholds for daily mean air temperature, or the daily sum of the positive snow energy balance. Additionally, the depth of the maximum water accumulation in the simulations showed a significant correlation with observed avalanche size. Direct output from detailed snow cover models thereby is able to provide a better regional assessment of dangerous slope aspects and potential avalanche size than traditional methods.

  14. A study of Gd-based parallel plate avalanche counter for thermal neutrons by MC simulation

    Energy Technology Data Exchange (ETDEWEB)

    Rhee, J.T.; Kim, H.G. [IAP, High Energy Physics Lab, Department of Physics, Konkuk University, Seoul 143-701 (Korea, Republic of); Ahmad, Farzana; Jeon, Y.J. [Liquid Crystal Research Center, Department of Chemistry, Konkuk University, Seoul 143-701 (Korea, Republic of); Jamil, M., E-mail: mjamil@konkuk.ac.kr [IAP, High Energy Physics Lab, Department of Physics, Konkuk University, Seoul 143-701 (Korea, Republic of); Division of International Studies, University College, Konkuk University, Seoul 143-701 (Korea, Republic of)

    2013-12-21

    In this work, we demonstrate the feasibility and characteristics of a single-gap parallel plate avalanche counter (PPAC) as a low energy neutron detector, based on Gd-converter coating. Upon falling on the Gd-converter surface, the incident low energy neutrons produce internal conversion electrons which are evaluated and detected. For estimating the performance of the Gd-based PPAC, a simulation study has been performed using GEANT4 Monte Carlo (MC) code. The detector response as a function of incident neutron energies in the range of 25–100 meV has been evaluated with two different physics lists. Using the QGSP{sub B}IC{sub H}P physics list and assuming 5μm converter thickness, 11.8%, 18.48%, and 30.28% detection efficiencies have been achieved for the forward-, the backward-, and the total response of the converter-based PPAC. On the other hand, considering the same converter thickness and detector configuration, with the QGSP{sub B}ERT{sub H}P physics list efficiencies of 12.19%, 18.62%, and 30.81%, respectively, were obtained. These simulation results are briefly discussed.

  15. A study of Gd-based parallel plate avalanche counter for thermal neutrons by MC simulation

    Science.gov (United States)

    Rhee, J. T.; Kim, H. G.; Ahmad, Farzana; Jeon, Y. J.; Jamil, M.

    2013-12-01

    In this work, we demonstrate the feasibility and characteristics of a single-gap parallel plate avalanche counter (PPAC) as a low energy neutron detector, based on Gd-converter coating. Upon falling on the Gd-converter surface, the incident low energy neutrons produce internal conversion electrons which are evaluated and detected. For estimating the performance of the Gd-based PPAC, a simulation study has been performed using GEANT4 Monte Carlo (MC) code. The detector response as a function of incident neutron energies in the range of 25-100 meV has been evaluated with two different physics lists. Using the QGSP_BIC_HP physics list and assuming 5 μm converter thickness, 11.8%, 18.48%, and 30.28% detection efficiencies have been achieved for the forward-, the backward-, and the total response of the converter-based PPAC. On the other hand, considering the same converter thickness and detector configuration, with the QGSP_BERT_HP physics list efficiencies of 12.19%, 18.62%, and 30.81%, respectively, were obtained. These simulation results are briefly discussed.

  16. A study of Gd-based parallel plate avalanche counter for thermal neutrons by MC simulation

    International Nuclear Information System (INIS)

    In this work, we demonstrate the feasibility and characteristics of a single-gap parallel plate avalanche counter (PPAC) as a low energy neutron detector, based on Gd-converter coating. Upon falling on the Gd-converter surface, the incident low energy neutrons produce internal conversion electrons which are evaluated and detected. For estimating the performance of the Gd-based PPAC, a simulation study has been performed using GEANT4 Monte Carlo (MC) code. The detector response as a function of incident neutron energies in the range of 25–100 meV has been evaluated with two different physics lists. Using the QGSPBICHP physics list and assuming 5μm converter thickness, 11.8%, 18.48%, and 30.28% detection efficiencies have been achieved for the forward-, the backward-, and the total response of the converter-based PPAC. On the other hand, considering the same converter thickness and detector configuration, with the QGSPBERTHP physics list efficiencies of 12.19%, 18.62%, and 30.81%, respectively, were obtained. These simulation results are briefly discussed

  17. Application of columnar cesium iodide (CsI) as a secondary-electron emission source to gas avalanche detectors

    International Nuclear Information System (INIS)

    A columnar cesium iodide (CsI) layer as a secondary-electron emission (SEE) source was applied to conventional gas avalanche detectors to improve their operating characteristics. The concentration of the primary electrons to a small interaction region allows gas avalanche detectors to have better spatial and timing resolutions. In this study, the signal enhancement and timing resolution of a microstrip gas chamber (MSGC) coupled with the columnar CsI layer were investigated. A large amount of electron amplification occurred within the columnar CsI layer when it was activated, greatly enhancing the signal pulse amplitude over that coming from the ionization in the gas drift region alone. The measured timing resolution of the MSGC detector having an anode width of 5 μm, a cathode width of 95 μm, and a pitch of 200 μm was about 5.5 ns rms at a reduced gas pressure to 30 torr. The SEE efficiency of the columnar CsI layer was also investigated and estimated with about 6%. (author)

  18. Non-Markovian property of afterpulsing effect in single-photon avalanche detector

    CERN Document Server

    Wang, Fang-Xiang; Li, Ya-Ping; He, De-Yong; Wang, Chao; Han, Yun-Guang; Wang, Shuang; Yin, Zhen-Qiang; Han, Zheng-Fu

    2016-01-01

    The single-photon avalanche photodiode(SPAD) has been widely used in research on quantum optics. The afterpulsing effect, which is an intrinsic character of SPAD, affects the system performance in most experiments and needs to be carefully handled. For a long time, afterpulsing has been presumed to be determined by the pre-ignition avalanche. We studied the afterpulsing effect of a commercial InGaAs/InP SPAD (The avalanche photodiode model is: Princeton Lightwave PGA-300) and demonstrated that its afterpulsing is non-Markovian, with a memory effect in the avalanching history. Theoretical analysis and experimental results clearly indicate that the embodiment of this memory effect is the afterpulsing probability, which increases as the number of ignition-avalanche pulses increase. This conclusion makes the principle of the afterpulsing effect clearer and is instructive to the manufacturing processes and afterpulsing evaluation of high-count-rate SPADs. It can also be regarded as a fundamental premise to handle ...

  19. GaN-Based, Low-Voltage Avalanche Photodiodes for Robust and Compact UV Imagers Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This Phase I SBIR program is directed toward the development of a novel low-voltage (~10V) AlGaN-based multi-quantum well (MQW) avalanche photodiode (APD) on...

  20. Extended Wavelength InP Based Avalanche Diodes for MWIR Response Project

    Data.gov (United States)

    National Aeronautics and Space Administration — For this NASA STTR program, we propose to develop a novel superlattice-based near infrared to midwave infrared avalanche photodetector (APD) grown on InP substrates...

  1. Non-Markov property of afterpulsing effect in single-photon avalanche detector

    CERN Document Server

    Wang, Fang-Xiang; Li, Ya-Ping; He, De-Yong; Wang, Chao; Han, Yun-Guang; Wang, Shuang; Yin, Zhen-Qiang; Han, Zheng-Fu

    2016-01-01

    Single-photon avalanche photodiode(SPAD) has been widely used in researching of quantum optics. Afterpulsing effect, which is an intrinsic character of SPAD, affects the system performance in most of the experiments and needs to be carefully handled. For a long time, afterpulsing has been presumed to be determined by the pre-ignition avalanche. We studied the afterpulsing effect of a commercial InGaAs/InP SPAD (APD: Princeton Lightwave PGA-300) and demonstrated that its afterpulsing is non-Markov, which has memory effect of the avalanching history. Theoretical analysis and the experimental results clearly indicate that the embodiment of this memory effect is the afterpulsing probability, which increases as the number of ignition-avalanche pulses increase. The conclusion makes the principle of afterpulsing effect clearer and is instructive to the manufacturing processes and afterpulsing evaluation of high-count-rate SPADs. It can also be regarded as an fundamental premise to handle the afterpulsing signals in ...

  2. Different Avalanche Behaviors in Different Specific Areas of a System Based on Neural Networks

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xiao-Wei; CHEN Tian-Lun

    2003-01-01

    Based on the standard self-organizing map (SOM) neural network model and an integrate-and-fire mecha-nism, we introduce a kind of coupled map lattice system to investigate scale-invariance behavior in the activity of modelneural populations. We find power-law distribution behavior of avalanche size in our model. But more importantly, wefind there are different avalanche distribution behaviors in different specific areas of our system, which are formed by thetopological learning process of the SOM net.

  3. An Ion Beam Tracking System based on a Parallel Plate Avalanche Counter

    Directory of Open Access Journals (Sweden)

    Carter I. P.

    2013-12-01

    Full Text Available A pair of twin position-sensitive parallel plate avalanche counters have been developed at the Australian National University as a tracking system to aid in the further rejection of unwanted beam particles from a 6.5 T super conducting solenoid separator named SOLEROO. Their function is to track and identify each beam particle passing through the detectors on an event-by-event basis. In-beam studies have been completed and the detectors are in successful operation, demonstrating the tracking capability. A high efficiency 512-pixelwide-angle silicon detector array will then be integrated with the tracking system for nuclear reactions studies of radioactive ions.

  4. Research and development on a sub 100 PICO second time-of-flight system based on silicon avalanche diodes

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Y.; Hirsch, A.; Hauger, A.; Scharenberg, R.; Tincknell, M. [Purdue Univ., West Lafayette, IN (United States); Rai, G. [Lawrence Berkeley Lab., CA (United States)

    1991-12-31

    Particle identification requires a momentum measurement and a second independent determination either energy loss (dE/dx) or time of flight (TOF). To cover a momentum range from 0.1 GeV/c to 1.5 GeV/c in the STAR detector requires both the dE/dx and TOF techniques. This research is designed to develop the avalanche diode (AVD) detectors for TOF systems and evaluate their performance. The test of a small prototype system would be carried out at Purdue and at accelerator test beam sites. The Purdue group has developed a complete test setup for evaluating the time resolution of the AVD`s which includes fast-slow electronic channels, CAMAC based electronic modules and a temperature controlled environment. The AVDs also need to be tested in a 0.5 tesla magnetic field. The Purdue group would augment this test set up to include a magnetic field.

  5. Polysiloxane based neutron detectors

    OpenAIRE

    Dalla Palma, Matteo

    2016-01-01

    In the last decade, neutron detection has been attracting the attention of the scientific community for different reasons. On one side, the increase in the price of 3He, employed in the most efficient and the most widely used neutron detectors. On the other side, the harmfulness of traditional xylene based liquid scintillators, used in extremely large volumes for the detection of fast neutrons. Finally, the demand for most compact and rough systems pushed by the increased popularity of neutro...

  6. Electron-avalanche amplifier based on the electronic Venturi effect

    Science.gov (United States)

    Taubert, D.; Schinner, G. J.; Tranitz, H. P.; Wegscheider, W.; Tomaras, C.; Kehrein, S.; Ludwig, S.

    2010-10-01

    Scattering of otherwise ballistic electrons far from equilibrium is investigated in a cold two-dimensional electron system. The interaction between excited electrons and the degenerate Fermi liquid induces a positive charge in a nanoscale region which would be negatively charged for diffusive transport at local thermal equilibrium. In a three-terminal device we observe avalanche amplification of electrical current, resulting in a situation comparable to the Venturi effect in hydrodynamics. Numerical calculations using a random-phase approximation are in agreement with our data and suggest Coulomb interaction as the dominant scattering mechanism.

  7. Avalanche proton-boron fusion based on elastic nuclear collisions

    Science.gov (United States)

    Eliezer, Shalom; Hora, Heinrich; Korn, Georg; Nissim, Noaz; Martinez Val, Josè Maria

    2016-05-01

    Recent experiments done at Prague with the 600 J/0.2 ns PALS laser interacting with a layer of boron dopants in a hydrogen enriched target have produced around 109 alphas. We suggest that these unexpected very high fusion reactions of proton with 11B indicate an avalanche multiplication for the measured anomalously high nuclear reaction yields. This can be explained by elastic nuclear collisions in the broad 600 keV energy band, which is coincident with the high nuclear p-11B fusion cross section, by the way of multiplication through generation of three secondary alpha particles from a single primarily produced alpha particle.

  8. Development of the HgCdTe Avalanche Photodiode Detectors and the Improvement in the CO2 Lidar Performance for the ASCENDS Mission

    Science.gov (United States)

    Sun, X.; Abshire, J. B.; Chen, J. R.; Ramanathan, A. K.; Mao, J.

    2015-12-01

    NASA Goddard Space Flight Center (GSFC) is developing the CO2 lidar as a candidate for the NASA's planned ASCENDS mission under the support of Earth Science Technology Office (ESTO) IIP and ATI-QRS programs. A new type of HgCdTe avalanche photodiode (APD) detector has been developed by the DRS Technologies under the IIP program. The new detectors achieved >70% quantum efficiency, including the effect of the fill factor, over the spectral range from 0.4 to 4.3 μm, which significantly improves the receiver performance of our CO2 lidar and enabled other remote sending measurements. The HgCdTe APD arrays have 80 μm square pixels in a 4x4 array along with a bank of 16 preamplifiers on the same chip carrier. Test results at both DRS and GSFC showed the HgCdTe APD array has achieved, an APD gain of 500-1000, 8-10 MHz electrical bandwidth, and an average noise equivalent power (NEP) of performance for at least a year. We have also updated the performance analysis of a space-based version of our CO2 lidar with the new HgCdTe APD detector. For the retrievals, a least-square-error method is used to fit the measured transmittances to a predetermined line shape function using 8 to 16 sampling wavelengths. The error in the derived total optical depth and the CO2 mixing ratio are estimated via the standard error propagation method. The error in the resultant CO2 mixing ratio is calculated as a function of the received optical signal power, including the effects of the laser energy, receiver telescope size, and solar background radiation noise. The presentation will give more details about the detector and its impact on our CO2 lidar for the ASCENDS mission.

  9. Different Avalanche Behaviors in Different Specific Areas of a System Based on Neural Networks

    Institute of Scientific and Technical Information of China (English)

    ZHAOXiao-Wei; CHENTian-Lun

    2003-01-01

    Based on the standard self-organizing map (SOM) neural network model and an integrate-and-fire mecha-nism, we introduce a kind of coupled map lattice system to investigate scale-invariance behavior in the activity of model neural populations. We find power-law distribution behavior of avalanche size in our model. But more importantly, we find there are different avalanche distribution behaviors in different specific areas of our system, which are formed by the topological learning process of the SOM net.

  10. Sensitivity Analysis of a Spatio-Temporal Avalanche Forecasting Model Based on Support Vector Machines

    Science.gov (United States)

    Matasci, G.; Pozdnoukhov, A.; Kanevski, M.

    2009-04-01

    The recent progress in environmental monitoring technologies allows capturing extensive amount of data that can be used to assist in avalanche forecasting. While it is not straightforward to directly obtain the stability factors with the available technologies, the snow-pack profiles and especially meteorological parameters are becoming more and more available at finer spatial and temporal scales. Being very useful for improving physical modelling, these data are also of particular interest regarding their use involving the contemporary data-driven techniques of machine learning. Such, the use of support vector machine classifier opens ways to discriminate the ``safe'' and ``dangerous'' conditions in the feature space of factors related to avalanche activity based on historical observations. The input space of factors is constructed from the number of direct and indirect snowpack and weather observations pre-processed with heuristic and physical models into a high-dimensional spatially varying vector of input parameters. The particular system presented in this work is implemented for the avalanche-prone site of Ben Nevis, Lochaber region in Scotland. A data-driven model for spatio-temporal avalanche danger forecasting provides an avalanche danger map for this local (5x5 km) region at the resolution of 10m based on weather and avalanche observations made by forecasters on a daily basis at the site. We present the further work aimed at overcoming the ``black-box'' type modelling, a disadvantage the machine learning methods are often criticized for. It explores what the data-driven method of support vector machine has to offer to improve the interpretability of the forecast, uncovers the properties of the developed system with respect to highlighting which are the important features that led to the particular prediction (both in time and space), and presents the analysis of sensitivity of the prediction with respect to the varying input parameters. The purpose of the

  11. Avalanche for shape and feature-based virtual screening with 3D alignment.

    Science.gov (United States)

    Diller, David J; Connell, Nancy D; Welsh, William J

    2015-11-01

    This report introduces a new ligand-based virtual screening tool called Avalanche that incorporates both shape- and feature-based comparison with three-dimensional (3D) alignment between the query molecule and test compounds residing in a chemical database. Avalanche proceeds in two steps. The first step is an extremely rapid shape/feature based comparison which is used to narrow the focus from potentially millions or billions of candidate molecules and conformations to a more manageable number that are then passed to the second step. The second step is a detailed yet still rapid 3D alignment of the remaining candidate conformations to the query conformation. Using the 3D alignment, these remaining candidate conformations are scored, re-ranked and presented to the user as the top hits for further visualization and evaluation. To provide further insight into the method, the results from two prospective virtual screens are presented which show the ability of Avalanche to identify hits from chemical databases that would likely be missed by common substructure-based or fingerprint-based search methods. The Avalanche method is extended to enable patent landscaping, i.e., structural refinements to improve the patentability of hits for deployment in drug discovery campaigns. PMID:26458937

  12. Analysis of avalanche risk factors in backcountry terrain based on usage frequency and accident data in Switzerland

    Science.gov (United States)

    Techel, F.; Zweifel, B.; Winkler, K.

    2015-09-01

    Recreational activities in snow-covered mountainous terrain in the backcountry account for the vast majority of avalanche accidents. Studies analyzing avalanche risk mostly rely on accident statistics without considering exposure (or the elements at risk), i.e., how many, when and where people are recreating, as data on recreational activity in the winter mountains are scarce. To fill this gap, we explored volunteered geographic information on two social media mountaineering websites - bergportal.ch and camptocamp.org. Based on these data, we present a spatiotemporal pattern of winter backcountry touring activity in the Swiss Alps and compare this with accident statistics. Geographically, activity was concentrated in Alpine regions relatively close to the main Swiss population centers in the west and north. In contrast, accidents occurred equally often in the less-frequented inner-alpine regions. Weekends, weather and avalanche conditions influenced the number of recreationists, while the odds to be involved in a severe avalanche accident did not depend on weekends or weather conditions. However, the likelihood of being involved in an accident increased with increasing avalanche danger level, but also with a more unfavorable snowpack containing persistent weak layers (also referred to as an old snow problem). In fact, the most critical situation for backcountry recreationists and professionals occurred on days and in regions when both the avalanche danger was critical and when the snowpack contained persistent weak layers. The frequently occurring geographical pattern of a more unfavorable snowpack structure also explains the relatively high proportion of accidents in the less-frequented inner-alpine regions. These results have practical implications: avalanche forecasters should clearly communicate the avalanche danger and the avalanche problem to the backcountry user, particularly if persistent weak layers are of concern. Professionals and recreationists, on the

  13. A parallel plate avalanche detector with four independent sections for time-of-flight measurements

    International Nuclear Information System (INIS)

    DRACULA-Phase III arrangement is quite similar to DRACULA-Phase II. The difference consists in replacement of the NaI crystals by HPGe detectors using new adjustable mechanical holders. For DRACULA-Phase III experimental configuration, a new START detector for time-of-flight measurements was designed and constructed. This is a double twin PPAD foreseen to satisfy the geometry of the new charged fragment-gamma ray coincidence experiment performed at 30 MeV/u incident energy at LNS-Catania. The new PPAD contains four independent sections working as follows: a) the sections 1 and 2 are matching with the geometry of the existing large area STOP-PPAD placed in front of the Big Ionization Chamber; b) the sections 3 and 4 are foreseen to deliver the START signals for two supplementary hybrid detectors, both consisting from 25 cm long resistive wire proportional counters (x, ΔE) followed by a NE-102A scintillator (ER) with 30 cm x 1.8 cm x 2.4 cm dimensions. The sections 3 and 4 have an opening of 24 angle and 6 angle in horizontal and vertical directions, respectively, covering an angular range from 2.5 angle up to 8.5 angle relative to the horizontal reaction plane. Thus, the hole detecting area of the two hybrid detectors placed at polar angles of ± 7 angle has been matched. The construction of this PPAD is very similar to the one reported in the literature. Having a double length, we provided it with three holes machined on the horizontal axis contained in the reaction plane and placed at 0 angle, 12 angle and 24 angle respectively, necessary to transport the beam far away at about 3 m distance to a Faraday cup. The detector was successfully used in the first experiment (58Ni(30 MeV/u) + 58Ni) with DRACULA-Phase III experimental configuration at LNS Catania Superconducting Cyclotron. (authors)

  14. Fluorescence-suppressed time-resolved Raman spectroscopy of pharmaceuticals using complementary metal-oxide semiconductor (CMOS) single-photon avalanche diode (SPAD) detector.

    Science.gov (United States)

    Rojalin, Tatu; Kurki, Lauri; Laaksonen, Timo; Viitala, Tapani; Kostamovaara, Juha; Gordon, Keith C; Galvis, Leonardo; Wachsmann-Hogiu, Sebastian; Strachan, Clare J; Yliperttula, Marjo

    2016-01-01

    In this work, we utilize a short-wavelength, 532-nm picosecond pulsed laser coupled with a time-gated complementary metal-oxide semiconductor (CMOS) single-photon avalanche diode (SPAD) detector to acquire Raman spectra of several drugs of interest. With this approach, we are able to reveal previously unseen Raman features and suppress the fluorescence background of these drugs. Compared to traditional Raman setups, the present time-resolved technique has two major improvements. First, it is possible to overcome the strong fluorescence background that usually interferes with the much weaker Raman spectra. Second, using the high photon energy excitation light source, we are able to generate a stronger Raman signal compared to traditional instruments. In addition, observations in the time domain can be performed, thus enabling new capabilities in the field of Raman and fluorescence spectroscopy. With this system, we demonstrate for the first time the possibility of recording fluorescence-suppressed Raman spectra of solid, amorphous and crystalline, and non-photoluminescent and photoluminescent drugs such as caffeine, ranitidine hydrochloride, and indomethacin (amorphous and crystalline forms). The raw data acquired by utilizing only the picosecond pulsed laser and a CMOS SPAD detector could be used for identifying the compounds directly without any data processing. Moreover, to validate the accuracy of this time-resolved technique, we present density functional theory (DFT) calculations for a widely used gastric acid inhibitor, ranitidine hydrochloride. The obtained time-resolved Raman peaks were identified based on the calculations and existing literature. Raman spectra using non-time-resolved setups with continuous-wave 785- and 532-nm excitation lasers were used as reference data. Overall, this demonstration of time-resolved Raman and fluorescence measurements with a CMOS SPAD detector shows promise in diverse areas, including fundamental chemical research, the

  15. Fluorescence-suppressed time-resolved Raman spectroscopy of pharmaceuticals using complementary metal-oxide semiconductor (CMOS) single-photon avalanche diode (SPAD) detector.

    Science.gov (United States)

    Rojalin, Tatu; Kurki, Lauri; Laaksonen, Timo; Viitala, Tapani; Kostamovaara, Juha; Gordon, Keith C; Galvis, Leonardo; Wachsmann-Hogiu, Sebastian; Strachan, Clare J; Yliperttula, Marjo

    2016-01-01

    In this work, we utilize a short-wavelength, 532-nm picosecond pulsed laser coupled with a time-gated complementary metal-oxide semiconductor (CMOS) single-photon avalanche diode (SPAD) detector to acquire Raman spectra of several drugs of interest. With this approach, we are able to reveal previously unseen Raman features and suppress the fluorescence background of these drugs. Compared to traditional Raman setups, the present time-resolved technique has two major improvements. First, it is possible to overcome the strong fluorescence background that usually interferes with the much weaker Raman spectra. Second, using the high photon energy excitation light source, we are able to generate a stronger Raman signal compared to traditional instruments. In addition, observations in the time domain can be performed, thus enabling new capabilities in the field of Raman and fluorescence spectroscopy. With this system, we demonstrate for the first time the possibility of recording fluorescence-suppressed Raman spectra of solid, amorphous and crystalline, and non-photoluminescent and photoluminescent drugs such as caffeine, ranitidine hydrochloride, and indomethacin (amorphous and crystalline forms). The raw data acquired by utilizing only the picosecond pulsed laser and a CMOS SPAD detector could be used for identifying the compounds directly without any data processing. Moreover, to validate the accuracy of this time-resolved technique, we present density functional theory (DFT) calculations for a widely used gastric acid inhibitor, ranitidine hydrochloride. The obtained time-resolved Raman peaks were identified based on the calculations and existing literature. Raman spectra using non-time-resolved setups with continuous-wave 785- and 532-nm excitation lasers were used as reference data. Overall, this demonstration of time-resolved Raman and fluorescence measurements with a CMOS SPAD detector shows promise in diverse areas, including fundamental chemical research, the

  16. Feasibility of Geiger-mode avalanche photodiodes in CMOS standard technologies for tracker detectors

    OpenAIRE

    Vilella Figueras, Eva

    2013-01-01

    The next generation of particle colliders will be characterized by linear lepton colliders, where the collisions between electrons and positrons will allow to study in great detail the new particle discovered at CERN in 2012 (presumably the Higgs boson). At present time, there are two alternative projects underway, namely the ILC (International Linear Collider) and CLIC (Compact LInear Collider). From the detector point of view, the physics aims at these particle colliders impose such extreme...

  17. Space-based detectors

    Science.gov (United States)

    Sesana, A.; Weber, W. J.; Killow, C. J.; Perreur-Lloyd, M.; Robertson, D. I.; Ward, H.; Fitzsimons, E. D.; Bryant, J.; Cruise, A. M.; Dixon, G.; Hoyland, D.; Smith, D.; Bogenstahl, J.; McNamara, P. W.; Gerndt, R.; Flatscher, R.; Hechenblaikner, G.; Hewitson, M.; Gerberding, O.; Barke, S.; Brause, N.; Bykov, I.; Danzmann, K.; Enggaard, A.; Gianolio, A.; Vendt Hansen, T.; Heinzel, G.; Hornstrup, A.; Jennrich, O.; Kullmann, J.; Møller-Pedersen, S.; Rasmussen, T.; Reiche, J.; Sodnik, Z.; Suess, M.; Armano, M.; Sumner, T.; Bender, P. L.; Akutsu, T.; Sathyaprakash, B. S.

    2014-12-01

    The parallel session C5 on Space-Based Detectors gave a broad overview over the planned space missions related to gravitational wave detection. Overviews of the revolutionary science to be expected from LISA was given by Alberto Sesana and Sasha Buchman. The launch of LISA Pathfinder (LPF) is planned for 2015. This mission and its payload "LISA Technology Package" will demonstrate key technologies for LISA. In this context, reference masses in free fall for LISA, and gravitational physics in general, was described by William Weber, laser interferometry at the pico-metre level and the optical bench of LPF was presented by Christian Killow and the performance of the LPF optical metrology system by Paul McNamara. While LPF will not yet be sensitive to gravitational waves, it may nevertheless be used to explore fundamental physics questions, which was discussed by Michele Armano. Some parts of the LISA technology that are not going to be demonstrated by LPF, but under intensive development at the moment, were presented by Oliver Jennrich and Oliver Gerberding. Looking into the future, Japan is studying the design of a mid-frequency detector called DECIGO, which was discussed by Tomotada Akutsu. Using atom interferometry for gravitational wave detection has also been recently proposed, and it was critically reviewed by Peter Bender. In the nearer future, the launch of GRACE Follow-On (for Earth gravity observation) is scheduled for 2017, and it will include a Laser Ranging Interferometer as technology demonstrator. This will be the first inter-spacecraft laser interferometer and has many aspects in common with the LISA long arm, as discussed by Andrew Sutton.

  18. Design, construction and setting of a parallel plate avalanche detector with coordinate read-out

    International Nuclear Information System (INIS)

    This detector planned for heavy ion experiments has the following dimensions: 150x210 mm2. Each coordinate of the trajectory is obtained from a plane of read-out wires located half-way between the two electrodes of each gap. Position read-out is made by the delay line method. Interpolating properties cancel out the effects of quantization due to the wires. Two gaps sharing a common electrode, with their wire-planes at 900, furnish the two coordinates. The common electrode (Anode) delivers a fast signal on each ion crossing. Formation of signals on the anode with their distortion by the associated circuit was calculated. Formation of signals on the wires and their distortion into the delay lines was also determined. This allowed to evaluate the influence of the various parameters leading to an optimum time and space resolution. With 252Cf fission products, 500 ps and 0.6 mm were so obtained. Differential linearity is better than 75 μm. Pulse height analysis of the anode signals makes discrimination between lightly and heavily ionizing ions possible

  19. Ultraviolet AlGaN-based Avalanche Photo Diode Grown over Single Crystal Bulk AlN Substrates Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Premature breakdown is a key obstacle in developing AlGaN-based avalanche photo diodes (APD) for ultraviolet (UV) light detection. Novel materials growth...

  20. Four-layer depth-of-interaction PET detector for high resolution PET using a multi-pixel S8550 avalanche photodiode

    Science.gov (United States)

    Nishikido, Fumihiko; Inadama, Naoko; Oda, Ichiro; Shibuya, Kengo; Yoshida, Eiji; Yamaya, Taiga; Kitamura, Keishi; Murayama, Hideo

    2010-09-01

    Avalanche photodiodes (APDs) are being used as photodetectors in positron emission tomography (PET) because they have many advantages over photomultipliers (PMTs) typically used in PET detectors. We have developed a PET detector that consists of a multi-pixel APD and a 6×6×4 array of 1.46×1.46 mm 2×4.5 m LYSO crystals for a small animal PET scanner. The detector can identify four-layer depth of interaction (DOI) with a position-sensitive APD coupled to the backside of a crystal array by just an optimized reflector arrangement. Since scintillation lights are shared among many pixels by the method, weaker signals in APD pixels far from the interacting crystals are affected by noise. To evaluate the performance of the four-layer DOI detector with the APD and the influence of electrical noise on our method, we constructed a prototype DOI detector and tested its performance. We found, except for crystal elements on the edge of the crystal array, all crystal elements could be identified from the 2D position histogram. An energy resolution of 16.9% was obtained for the whole crystal array of the APD detector. The results of noise dependence of detector performances indicated that the DOI detector using the APD could achieve sufficient performance even when using application-specific integrated circuits.

  1. Four-layer depth-of-interaction PET detector for high resolution PET using a multi-pixel S8550 avalanche photodiode

    Energy Technology Data Exchange (ETDEWEB)

    Nishikido, Fumihiko, E-mail: funis@nirs.go.j [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Inadama, Naoko [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Oda, Ichiro [Shimadzu Corporation, Nishinokyo Kuwabaracho 1 Nakagyo-ku, Kyoto-shi, Kyoto 604-8511 (Japan); Shibuya, Kengo; Yoshida, Eiji; Yamaya, Taiga [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Kitamura, Keishi [Shimadzu Corporation, Nishinokyo Kuwabaracho 1 Nakagyo-ku, Kyoto-shi, Kyoto 604-8511 (Japan); Murayama, Hideo [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan)

    2010-09-21

    Avalanche photodiodes (APDs) are being used as photodetectors in positron emission tomography (PET) because they have many advantages over photomultipliers (PMTs) typically used in PET detectors. We have developed a PET detector that consists of a multi-pixel APD and a 6x6x4 array of 1.46x1.46 mm{sup 2}x4.5 m LYSO crystals for a small animal PET scanner. The detector can identify four-layer depth of interaction (DOI) with a position-sensitive APD coupled to the backside of a crystal array by just an optimized reflector arrangement. Since scintillation lights are shared among many pixels by the method, weaker signals in APD pixels far from the interacting crystals are affected by noise. To evaluate the performance of the four-layer DOI detector with the APD and the influence of electrical noise on our method, we constructed a prototype DOI detector and tested its performance. We found, except for crystal elements on the edge of the crystal array, all crystal elements could be identified from the 2D position histogram. An energy resolution of 16.9% was obtained for the whole crystal array of the APD detector. The results of noise dependence of detector performances indicated that the DOI detector using the APD could achieve sufficient performance even when using application-specific integrated circuits.

  2. Influence of temperature and bias voltage on the performance of a high resolution PET detector built with position sensitive avalanche photodiodes

    Science.gov (United States)

    Vandenbroucke, A.; McLaughlin, T. J.; Levin, C. S.

    2012-08-01

    We evaluate the performance of an 8 × 8 array of 0.9 × 0.9 × 1 mm3 cerium doped lutetium oxyothosilicate (LSO) crystals coupled to a position sensitive avalanche photodiode (PSAPD) as a function of bias voltage and temperature. We use this detector to develop a general methodology to optimize bias voltage, temperature, and gain for PET detectors using semiconductor photodetectors. This detector module will be used in a novel high resolution positron emission tomography (PET) camera dedicated to breast imaging under construction in our lab. Due to the tight packing of many PSAPDs in the system a thermal gradient is expected across the imaging heads. Data were collected for 11 PSAPD temperatures between 5°C and 40°C using a thermo-electric (Peltier) device. At each temperature the bias voltage was varied in steps of 5 V over a 50 V range. We present three methods to predict the optimal bias voltage at every temperature: one based on optimizing the coincidence time resolution, the others based on the relative change in PSAPD gain and leakage current due to the onset of hole multiplication. Optimal gain could also be predicted based on the quality of the flood histogram. At optimal bias voltage, the energy resolution degrades as (10.5±0.1)+((0.038±0.006)/ °C·T)%. Time resolution stays constant at 2.37±0.02 ns below 15°C. Above this temperature, time resolution deteriorates as (1.67±0.06)+((0.042±0.002)/°C·T)ns. Even at high temperatures, all 64 crystal position peaks in the flood histogram are still clearly visible. The width of the peaks in the flood histogram show a quadratic degradation with temperature: (2.6±0.1)·10-2+(1.6±0.2)·10-5/(°C)2·T2. We conclude that both the quality of the flood histogram as well as the coincidence time resolution are better parameters to estimate the optimal bias voltage, than energy resolution. Optimal bias voltage is found to be dependent on the value of k, the ratio between hole and electron multiplication. We

  3. Single electron multiplication distribution in GEM avalanches

    CERN Document Server

    Laszlo, Andras; Kiss, Gabor; Varga, Dezso

    2016-01-01

    In this paper measurement results and experimental methodology is presented on the determination of multiplication distributions of avalanches in GEM foils initiated by a single electron. The measurement relies on the amplification of photoelectrons by the GEM under study, which is subsequently amplified in an MWPC. The intrinsic detector resolution, namely the sigma over mean ratio of this distribution is also elaborated. Small gain dependence of the avalanche size is observed in the range of net effective gain of 15 to 100. The distribution has an exponentially decaying tail at large amplitudes, whereas the applied working gas is seen to have a well visible effect on the shape of the multiplication distribution at low amplitudes; or equivalently, the working gas has an influence on the intrinsic detector resolution of GEMs via suppression of the low amplitude responses. A sigma over mean ratio down to 0.75 was reached using neon based mixture, whereas other gases provided an intrinsic detector resolution cl...

  4. Design, fabrication and characterisation of InGaAs/InP single-photon avalanche diode detectors

    CERN Document Server

    Warburton, R E; Tan, L; Ng, J S; Krysa, A; Groom, K; David, J P R; Cova, S; Buller, G S; Warburton, Ryan E.; Pellegrini, Sara; Tan, Lionel; Ng, Jo Shien; Krysa, Andrey; Groom, Kris; David, John P.R.; Cova, Sergio; Buller, Gerald S.

    2006-01-01

    This paper demonstrates the performance of planar geometry InGaAs/InP avalanche diodes, specifically designed and fabricated for Geiger-mode operation at wavelengths around 1550nm, in terms of dark count rate, single-photon detection efficiency, afterpulsing and photon-timing jitter.

  5. Automated identification of potential snow avalanche release areas based on digital elevation models

    Directory of Open Access Journals (Sweden)

    Y. Bühler

    2013-05-01

    Full Text Available The identification of snow avalanche release areas is a very difficult task. The release mechanism of snow avalanches depends on many different terrain, meteorological, snowpack and triggering parameters and their interactions, which are very difficult to assess. In many alpine regions such as the Indian Himalaya, nearly no information on avalanche release areas exists mainly due to the very rough and poorly accessible terrain, the vast size of the region and the lack of avalanche records. However avalanche release information is urgently required for numerical simulation of avalanche events to plan mitigation measures, for hazard mapping and to secure important roads. The Rohtang tunnel access road near Manali, Himachal Pradesh, India, is such an example. By far the most reliable way to identify avalanche release areas is using historic avalanche records and field investigations accomplished by avalanche experts in the formation zones. But both methods are not feasible for this area due to the rough terrain, its vast extent and lack of time. Therefore, we develop an operational, easy-to-use automated potential release area (PRA detection tool in Python/ArcGIS which uses high spatial resolution digital elevation models (DEMs and forest cover information derived from airborne remote sensing instruments as input. Such instruments can acquire spatially continuous data even over inaccessible terrain and cover large areas. We validate our tool using a database of historic avalanches acquired over 56 yr in the neighborhood of Davos, Switzerland, and apply this method for the avalanche tracks along the Rohtang tunnel access road. This tool, used by avalanche experts, delivers valuable input to identify focus areas for more-detailed investigations on avalanche release areas in remote regions such as the Indian Himalaya and is a precondition for large-scale avalanche hazard mapping.

  6. Integrated avalanche photodiode arrays

    Energy Technology Data Exchange (ETDEWEB)

    Harmon, Eric S.

    2015-07-07

    The present disclosure includes devices for detecting photons, including avalanche photon detectors, arrays of such detectors, and circuits including such arrays. In some aspects, the detectors and arrays include a virtual beveled edge mesa structure surrounded by resistive material damaged by ion implantation and having side wall profiles that taper inwardly towards the top of the mesa structures, or towards the direction from which the ion implantation occurred. Other aspects are directed to masking and multiple implantation and/or annealing steps. Furthermore, methods for fabricating and using such devices, circuits and arrays are disclosed.

  7. Development of high performance Avalanche Photodiodes and dedicated analog systems for HXI/SGD detectors onboard the Astro-H mission

    International Nuclear Information System (INIS)

    Hard X-ray Imager and Soft Gamma-ray Detector are being developed as onboard instruments for the Astro-H mission, which is scheduled for launch in 2014. In both detectors, BGO scintillators play key roles in achieving high sensitivity in low Earth orbit (LEO), by generating active veto signals to reject cosmic-ray events and gamma-ray backgrounds from radio-activated detector materials. In order to maximize background rejection power, it is also important to minimize the energy threshold of this shield. As a readout sensor of weak scintillation light from a number of BGO crystals in a complicated detector system, high performance, reverse-type Avalanche Photodiodes (APDs), with an effective area of 10×10mm2 are being employed, instead of bulky photomultiplier tubes (PMTs).Another advantage of using APDs is their low power consumption, although the relatively low gain of APDs (compared to conventional PMTs) requires dedicated analog circuits for noise suppression. In this paper, we report on the development and performance of APD detectors specifically designed for the Astro-H mission. In addition to APD performance, various environmental tests, including radiation hardness and qualification thermal cycling, will be described in detail. Moreover, a dedicated charge sensitive amplifier and analog filters are newly developed and tested here to optimize the performance of APDs to activate fast veto signals within a few μs from the BGO trigger. We will also report on overall performance testing of a prototype BGO detector system that mimics the data acquisition system onboard Astro-H.

  8. Dark-current characteristics of GaN-based UV avalanche photodiodes

    Science.gov (United States)

    Xu, Jintong; Chang, Chao; Li, Xiangyang

    2015-04-01

    For UV detecting, it needs high ratio of signal to noise, which means high responsibility and low noise. GaN-based avalanche photodiodes can provide a high internal photocurrent gain. In this paper, we report the testing and characterization of GaN based thin film materials, optimization design of device structure, the device etching and passivation technology, and the photoelectric characteristics of the devices. Also, uniformity of the device was obtained. The relationship between dark current and material quality or device processes was the focus of this study. GaN based material with high aluminum components have high density defects. Scanning electron microscope, cathodoluminescence spectra, X-ray double crystal diffraction and transmission spectroscopy testing were employed to evaluate the quality of GaN-based material. It shows that patterned sapphire substrate or thick AlN buffer layer is more effective to get high quality materials. GaN-based materials have larger hole ionization coefficient, so back incident structure were adopted to maximize the hole-derived multiplication course and it was helped to get a smaller multiplication noise. The device with separate absorption and multiplication regions is also prospective to reduce the avalanche noise. According to AlGaN based material characteristics and actual device fabrication, device structure was optimized further. Low physical damage inductively coupled plasma (ICP) etching method was used to etch mesa and wet etching method was employed to treat mesa damage. Silica is passivation material of device mesa. For solar-blind ultraviolet device, it is necessary to adopt a wider bandgap material than AlGaN material. The current-voltage characteristics under reverse bias were measured in darkness and under UV illumination. The distribution of dark current and response of different devices was obtained. In short, for GaN-based UV avalanche photodiode, dark current was related to high density dislocation of

  9. Sub-bandgap linear-absorption-based photodetectors in avalanche mode in PN-diode-integrated silicon microring resonators.

    Science.gov (United States)

    Li, Yu; Feng, Shaoqi; Zhang, Yu; Poon, Andrew W

    2013-12-01

    We report a sub-bandgap linear-absorption-based photodetector in avalanche mode at 1550 nm in a PN-diode-integrated silicon microring resonator. The photocurrent is primarily generated by the defect-state absorption introduced by the boron and phosphorous ion implantation during the PN diode formation. The responsivity is enhanced by both the cavity effect and the avalanche multiplication. We measure a responsivity of ~72.8 mA/W upon 8 V at cavity resonances in avalanche mode, corresponding to a gain of ~72 relative to the responsivity of ~1.0 mA/W upon 3 V at cavity resonances in normal mode. Our device exhibits a 3 dB bandwidth of ~7 GHz and an open eye diagram at 15 Gbit/s upon 8 V.

  10. Snow Avalanches

    Science.gov (United States)

    Ancey, C.

    Over the last century, mountain ranges in Europe and North America have seen substantial development due to the increase in recreational activities, transportation, construction in high altitude areas, etc. In these mountain ranges, avalanches often threaten man's activities and life. Typical examples include recent disasters, such as the avalanche at Val d'Isère in 1970 (39 people were killed in a hostel) or the series of catastrophic avalanches throughout the Northern Alps in February 1999 (62 residents killed). The rising demand for higher safety measures has given new impetus to the development of mitigation technology and has given rise to a new scientific area entirely devoted to snow and avalanches. This paper summarises the paramount features of avalanches (formation and motion) and outlines the main approaches used for describing their movement. We do not tackle specific problems related to snow mechanics and avalanche forecasting. For more information on the subject, the reader is referred to the main textbooks published in Alpine countries [1-8].

  11. Amorphous silicon based particle detectors

    OpenAIRE

    Wyrsch, N; Franco, A; Riesen, Y.; Despeisse, M; S. Dunand; Powolny, F; Jarron, P.; Ballif, C.

    2012-01-01

    Radiation hard monolithic particle sensors can be fabricated by a vertical integration of amorphous silicon particle sensors on top of CMOS readout chip. Two types of such particle sensors are presented here using either thick diodes or microchannel plates. The first type based on amorphous silicon diodes exhibits high spatial resolution due to the short lateral carrier collection. Combination of an amorphous silicon thick diode with microstrip detector geometries permits to achieve micromete...

  12. Avalanche risk in backcountry terrain based on usage frequency and accident data

    Directory of Open Access Journals (Sweden)

    F. Techel

    2014-08-01

    Full Text Available In Switzerland, the vast majority of avalanche accidents occurs during recreational activities. Risk analysis studies mostly rely on accident statistics without considering exposure (or the elements at risk, i.e. how many and where people are recreating. We compared the accident data (backcountry touring with reports from two social media mountaineering networks – bergportal.ch and camptocamp.org. On these websites, users reported more than 15 000 backcountry tours during the five winters 2009/2010 to 2013/2014. We noted similar patterns in avalanche accident data and user data like demographics of recreationists, distribution of the day of the week (weekday vs. weekend or weather conditions (fine vs. poor weather. However, we also found differences such as the avalanche danger conditions on days with activities and accidents, but also the geographic distribution. While backcountry activities are concentrated in proximity to the main population centres in the West and North of the Swiss Alps, a large proportion of the severe avalanche accidents occurred in the inner-alpine, more continental regions with frequently unfavorably snowpack structure. This suggests that even greater emphasis should be put on the type of avalanche problem in avalanche education and avalanche forecasting to increase the safety of backcountry recreationists.

  13. 3D near-infrared imaging based on a single-photon avalanche diode array sensor

    NARCIS (Netherlands)

    Mata Pavia, J.; Charbon, E.; Wolf, M.

    2011-01-01

    An imager for optical tomography was designed based on a detector with 128x128 single-photon pixels that included a bank of 32 time-to-digital converters. Due to the high spatial resolution and the possibility of performing time resolved measurements, a new contact-less setup has been conceived in w

  14. A PMT-like high gain avalanche photodiode based on GaN/AlN periodical stacked structure

    CERN Document Server

    Zheng, Ji-yuan; Yang, Di; Yu, Jia-dong; Meng, Xiao; E, Yan-xiong; Wu, Chao; Hao, Zhi-biao; Sun, Chang-zheng; Xiong, Bing; Luo, Yi; Han, Yan-jian; Wang, Jian; Li, Hong-tao; Brault, Julien; Matta, Samuel; Khalfioui, Mohamed Al; Yan, Jian-chang; Wei, Tong-bo; Zhang, Yun; Wang, Jun-xi

    2016-01-01

    Avalanche photodiode (APD) has been intensively investigated as a promising candidate to replace photomultiplier tubes (PMT) for weak light detection. However, in conventional APDs, a large portion of carrier energy drawn from the electric field is thermalized, and the multiplication efficiencies of electron and hole are low and close. In order to achieve high gain, the device should work under breakdown bias, where carrier multiplication proceeds bi-directionally to form a positive feedback multiplication circle. However, breakdown is hard to control, in practice, APDs should work under Geiger mode as a compromise between sustainable detection and high gain. The complexity of system seriously restricts the application. Here, we demonstrate an avalanche photodiode holding high gain without breakdown, which means no quenching circuit is needed for sustainable detection. The device is based on a GaN/AlN periodically-stacked-structure (PSS), wherein electron holds much higher efficiency than hole to draw energy ...

  15. Geiger-Mode Avalanche Photodiode Arrays Integrated to All-Digital CMOS Circuits

    Science.gov (United States)

    Aull, Brian

    2016-01-01

    This article reviews MIT Lincoln Laboratory's work over the past 20 years to develop photon-sensitive image sensors based on arrays of silicon Geiger-mode avalanche photodiodes. Integration of these detectors to all-digital CMOS readout circuits enable exquisitely sensitive solid-state imagers for lidar, wavefront sensing, and passive imaging. PMID:27070609

  16. Geiger-Mode Avalanche Photodiode Arrays Integrated to All-Digital CMOS Circuits

    OpenAIRE

    Brian Aull

    2016-01-01

    This article reviews MIT Lincoln Laboratory's work over the past 20 years to develop photon-sensitive image sensors based on arrays of silicon Geiger-mode avalanche photodiodes. Integration of these detectors to all-digital CMOS readout circuits enable exquisitely sensitive solid-state imagers for lidar, wavefront sensing, and passive imaging.

  17. Geiger-Mode Avalanche Photodiode Arrays Integrated to All-Digital CMOS Circuits

    Directory of Open Access Journals (Sweden)

    Brian Aull

    2016-04-01

    Full Text Available This article reviews MIT Lincoln Laboratory's work over the past 20 years to develop photon-sensitive image sensors based on arrays of silicon Geiger-mode avalanche photodiodes. Integration of these detectors to all-digital CMOS readout circuits enable exquisitely sensitive solid-state imagers for lidar, wavefront sensing, and passive imaging.

  18. Geiger-Mode Avalanche Photodiode Arrays Integrated to All-Digital CMOS Circuits.

    Science.gov (United States)

    Aull, Brian

    2016-01-01

    This article reviews MIT Lincoln Laboratory's work over the past 20 years to develop photon-sensitive image sensors based on arrays of silicon Geiger-mode avalanche photodiodes. Integration of these detectors to all-digital CMOS readout circuits enable exquisitely sensitive solid-state imagers for lidar, wavefront sensing, and passive imaging. PMID:27070609

  19. Cosmic Ray Measurements by Scintillators with Metal Resistor Semiconductor Avalanche Photo Diodes

    Science.gov (United States)

    Blanco, Francesco; La Rocca, Paola; Riggi, Francesco; Akindinov, Alexandre; Mal'kevich, Dmitry

    2008-01-01

    An educational set-up for cosmic ray physics experiments is described. The detector is based on scintillator tiles with a readout through metal resistor semiconductor (MRS) avalanche photo diode (APD) arrays. Typical measurements of the cosmic angular distribution at sea level and a study of the East-West asymmetry obtained by such a device are…

  20. A novel camera type for very high energy gamma-ray astronomy based on Geiger-mode avalanche photodiodes

    CERN Document Server

    Anderhub, H; Biland, A; Boller, A; Braun, I; Bretz, T; Commichau, S; Commichau, V; Dorner, D; Gendotti, A; Grimm, O; von Gunten, H; Hildebrand, D; Horisberger, U; Krähenbühl, T; Kranich, D; Lorenz, E; Lustermann, W; Mannheim, K; Neise, D; Pauss, F; Renker, D; Rhode, W; Rissi, M; Röser, U; Rollke, S; Stark, L S; Stucki, J -P; Viertel, G; Vogler, P; Weitzel, Q

    2009-01-01

    Geiger-mode avalanche photodiodes (G-APD) are promising new sensors for light detection in atmospheric Cherenkov telescopes. In this paper, the design and commissioning of a 36-pixel G-APD prototype camera is presented. The data acquisition is based on the Domino Ring Sampling (DRS2) chip. A sub-nanosecond time resolution has been achieved. Cosmic-ray induced air showers have been recorded using an imaging mirror setup, in a self-triggered mode. This is the first time that such measurements have been carried out with a complete G-APD camera.

  1. A novel camera type for very high energy gamma-ray astronomy based on Geiger-mode avalanche photodiodes

    Energy Technology Data Exchange (ETDEWEB)

    Anderhub, H; Biland, A; Boller, A; Braun, I; Commichau, S; Commichau, V; Dorner, D; Gendotti, A; Grimm, O; Gunten, H von; Hildebrand, D; Horisberger, U; Kraehenbuehl, T; Kranich, D; Lorenz, E; Lustermann, W [Institute for Particle Physics, ETH Zurich, Schafmattstr. 20, 8093 Zurich (Switzerland); Backes, M; Neise, D [TU Dortmund University, Otto-Hahn-Str. 4, 44227 Dortmund (Germany); Bretz, T; Mannheim, K [University of Wuerzburg Am Hubland, 97074 Wuerzburg (Germany)], E-mail: qweitzel@phys.ethz.ch (and others)

    2009-10-15

    Geiger-mode avalanche photodiodes (G-APD) are promising new sensors for light detection in atmospheric Cherenkov telescopes. In this paper, the design and commissioning of a 36-pixel G-APD prototype camera is presented. The data acquisition is based on the Domino Ring Sampling (DRS2) chip. A sub-nanosecond time resolution has been achieved. Cosmic-ray induced air showers have been recorded using an imaging mirror setup, in a self-triggered mode. This is the first time that such measurements have been carried out with a complete G-APD camera.

  2. Model of turn-on characteristics of InP-based Geiger-mode avalanche photodiodes suitable for circuit simulations

    Science.gov (United States)

    Jordy, George; Donnelly, Joseph

    2015-05-01

    A model for the turn-on characteristics of separate-absorber-multiplier InP-based Geiger-mode Avalanche Photodiodes (APDs) has been developed. Verilog-A was used to implement the model in a manner that can be incorporated into circuit simulations. Rather than using SPICE elements to mimic the voltage and current characteristics of the APD, Verilog-A can represent the first order nonlinear differential equations that govern the avalanche current of the APD. This continuous time representation is fundamentally different than the piecewise linear characteristics of other models. The model is based on a driving term for the differential current, which is given by the voltage overbias minus the voltage drop across the device's space-charge resistance RSC. This drop is primarily due to electrons transiting the separate absorber. RSC starts off high and decreases with time as the initial breakdown filament spreads laterally to fill the APD. With constant bias voltage, the initial current grows exponentially until space charge effects reduce the driving function. With increasing current the driving term eventually goes to zero and the APD current saturates. On the other hand, if the APD is biased with a capacitor, the driving term becomes negative as the capacitor discharges, reducing the current and driving the voltage below breakdown. The model parameters depend on device design and are obtained from fitting the model to Monte-Carlo turn-on simulations that include lateral spreading of the carriers of the relevant structure. The Monte-Carlo simulations also provide information on the probability of avalanche, and jitter due to where the photon is absorbed in the APD.

  3. Turn-key Near-Infrared Photon-Counting Detector Module for LIDAR Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to design and deliver a turn-key photon counting detector module for near-infrared wavelengths, based on large-area InGaAs/InP avalanche photodiodes...

  4. X-ray source based on open gaseous diode at supershot avalanche electron beam

    International Nuclear Information System (INIS)

    The formation of a volume discharge in an open gas diode with coaxial electrodes filled with air at atmospheric pressure was accompanied by hard X-ray emission. The conditions of supershort avalanche electron beam formation are retained at a pulse repetition rate up to 1.5 kHz. X radiation formed by 60 keV electrons is recorded by using high-voltage nanosecond pulses and by formation of volume discharges in open gas diodes filled with air at atmospheric pressure

  5. Radiation detectors based by polymer materials

    International Nuclear Information System (INIS)

    Scintillation counters make use of the property of certain chemical compounds to emit short light pulses after excitation produced by the passage of charged particles or photons of high energy. These flashes of light are detected by a photomultiplier tube that converts the photons into a voltage pulse. The light emitted from the detector also can be collected, focussed and dispersed by a CCD detector. The study of the evolution of the light emission and of the radiation damage under irradiation is a primary topic in the development of radiation hard polymer based scintillator. Polymer scintillator thin films are used in monitoring radiation beam intensities and simultaneous counting of different radiations. Radiation detectors have characteristics which depend on: the type of radiation, the energy of radiation, and the material of the detector. Three types of polymer thin films were studied: a polyvinyltoluene based scintillator, fluorinated polyimide and PMMA. (authors)

  6. Results from prototypes of environmental and health alarm devices based on gaseous detectors operating in air in counting mode

    CERN Document Server

    Martinengo, P; Peskov, V; Benaben, P; Charpak, G; Breuil, P

    2011-01-01

    We have developed and successfully tested two prototypes of detectors of dangerous gases based on wire-type counters operating in air in avalanche mode: one is for radon (Rn) detection whereas the other one is for the detection of gases with an ionization potential less than the air components. Due to the operation in pulse counting mode these prototypes have sensitivities comparable to (in the case of the Rn detector) or much higher than (in the case of the detector for low ionization gases) the best commercial devices currently available on the market. We believe that due to their high sensitivity, simplicity and low cost such new detectors will find massive applications. One of them, discussed in this paper, could be the on-line monitoring of Rn for the prediction of earthquakes. (C) 2010 Elsevier B.V. All rights reserved.

  7. Ion chamber based neutron detectors

    Science.gov (United States)

    Derzon, Mark S; Galambos, Paul C; Renzi, Ronald F

    2014-12-16

    A neutron detector with monolithically integrated readout circuitry, including: a bonded semiconductor die; an ion chamber formed in the bonded semiconductor die; a first electrode and a second electrode formed in the ion chamber; a neutron absorbing material filling the ion chamber; and the readout circuitry which is electrically coupled to the first and second electrodes. The bonded semiconductor die includes an etched semiconductor substrate bonded to an active semiconductor substrate. The readout circuitry is formed in a portion of the active semiconductor substrate. The ion chamber has a substantially planar first surface on which the first electrode is formed and a substantially planar second surface, parallel to the first surface, on which the second electrode is formed. The distance between the first electrode and the second electrode may be equal to or less than the 50% attenuation length for neutrons in the neutron absorbing material filling the ion chamber.

  8. Analysis and modeling of optical crosstalk in InP-based Geiger-mode avalanche photodiode FPAs

    Science.gov (United States)

    Chau, Quan; Jiang, Xudong; Itzler, Mark A.; Entwistle, Mark; Piccione, Brian; Owens, Mark; Slomkowski, Krystyna

    2015-05-01

    Optical crosstalk is a major factor limiting the performance of Geiger-mode avalanche photodiode (GmAPD) focal plane arrays (FPAs). This is especially true for arrays with increased pixel density and broader spectral operation. We have performed extensive experimental and theoretical investigations on the crosstalk effects in InP-based GmAPD FPAs for both 1.06-μm and 1.55-μm applications. Mechanisms responsible for intrinsic dark counts are Poisson processes, and their inter-arrival time distribution is an exponential function. In FPAs, intrinsic dark counts and cross talk events coexist, and the inter-arrival time distribution deviates from purely exponential behavior. From both experimental data and computer simulations, we show the dependence of this deviation on the crosstalk probability. The spatial characteristics of crosstalk are also demonstrated. From the temporal and spatial distribution of crosstalk, an efficient algorithm to identify and quantify crosstalk is introduced.

  9. Detector Based Radio Tomographic Imaging

    OpenAIRE

    Yiğitler, Hüseyin; Jäntti, Riku; Kaltiokallio, Ossi; Patwari, Neal

    2016-01-01

    Received signal strength based radio tomographic imaging is a popular device-free indoor localization method which reconstructs the spatial loss field of the environment using measurements from a dense wireless network. Existing methods solve an associated inverse problem using algebraic or compressed sensing reconstruction algorithms. We propose an alternative imaging method that reconstructs spatial field of occupancy using a back-projection based reconstruction algorithm. The introduced sy...

  10. Track Based Alignment of Composite Detector Structures

    CERN Document Server

    Karimäki, V; Schilling, F P

    2006-01-01

    An iterative algorithm for track based alignment is presented. The algorithm can be applied to rigid composite detector structures or to individual modules. The iterative process involves track reconstruction and alignment, in which the chi-2 function of the hit residuals of each alignable object is minimized. Six alignment parameters per structure or per module, three for location and three for orientation, can be computed. The method is computationally light and easily parallelizable. The performance of the method is demonstrated with simulated tracks in the CMS pixel detector and tracks reconstructed from experimental data recorded with a test beam setup.

  11. Multiuser detector based on wavelet networks

    Institute of Scientific and Technical Information of China (English)

    王伶; 焦李成; 陶海红; 刘芳

    2004-01-01

    Multiple access interference (MAI) and near-far problem are two major obstacles in DS-CDMA systems.Combining wavelet neural networks and two matched filters, the novel multiuser detector, which is based on multiple variable function estimation wavelet networks over single path asynchronous channel and space-time channel respectively is presented. Excellent localization characteristics of wavelet functions in both time and frequency domains allowed hierarchical multiple resolution learning of input-output data mapping. The mathematic frame of the neural networks and error back ward propagation algorithm are introduced. The complexity of the multiuser detector only depends on that of wavelet networks. With numerical simulations and performance analysis, it indicates that the multiuser detector has excellent performance in eliminating MAI and near-far resistance.

  12. Determination of snow avalanche return periods using a tree-ring based reconstruction in the French Alps: cross validation with the predictions of a statistical-dynamical model

    Science.gov (United States)

    Schläppy, Romain; Eckert, Nicolas; Jomelli, Vincent; Grancher, Delphine; Brunstein, Daniel; Stoffel, Markus; Naaim, Mohamed

    2013-04-01

    Documenting past avalanche activity represents an indispensable step in avalanche hazard assessment. Nevertheless, (i) archival records of past avalanche events do not normally yield data with satisfying spatial and temporal resolution and (ii) precision concerning runout distance is generally poorly defined. In addition, historic documentation is most often (iii) biased toward events that caused damage to structure or loss of life on the one hand and (iv) undersampled in unpopulated areas on the other hand. On forested paths dendrogeomorphology has been demonstrated to represent a powerful tool to reconstruct past activity of avalanches with annual resolution and for periods covering the past decades to centuries. This method is based on the fact that living trees may be affected by snow avalanches during their flow and deposition phases. Affected trees will react upon these disturbances with a certain growth response. An analysis of the responses recorded in tree rings coupled with an evaluation of the position of reacting trees within the path allows the dendrogeomorphic expert to identify past snow avalanche events and deduced their minimum runout distance. The objective of the work presented here is firstly to dendrochronogically -reconstruct snow avalanche activity in the Château Jouan path located near Montgenèvre in the French Alps. Minimal runout distances are then determined for each reconstructed event by considering the point of further reach along the topographic profile. Related empirical return intervals are evaluated, combining the extent of each event with the average local frequency of the dendrological record. In a second step, the runout distance distribution derived from dendrochronological reconstruction is compared to the one derived from historical archives and to high return period avalanches predicted by an up-to-date locally calibrated statistical-numerical model. It appears that dendrochronological reconstructions correspond mostly to

  13. Norm based Threshold Selection for Fault Detectors

    DEFF Research Database (Denmark)

    Rank, Mike Lind; Niemann, Henrik

    1998-01-01

    The design of fault detectors for fault detection and isolation (FDI) in dynamic systems is considered from a norm based point of view. An analysis of norm based threshold selection is given based on different formulations of FDI problems. Both the nominal FDI problem as well as the uncertain FDI...... problem are considered. Based on this analysis, a performance index based on norms of the involved transfer functions is given. The performance index allows us also to optimize the structure of the fault detection filter directly...

  14. New μSR spectrometer at J-PARC MUSE based on Kalliope detectors

    International Nuclear Information System (INIS)

    We developed a new positron detector system called Kalliope, which is based on multi-pixel avalanch photo-diode (m-APD), application specific integrated circuit (ASIC), field programmable gated array (FPGA) and ethernet-based SiTCP data transfer technology. We have manufactured a general-purpose spectrometer for muon spin relaxation (μSR) measurements, employing 40 Kalliope units (1280 channels of scintillators) installed in a 0.4 T longitudinal-field magnet. The spectrometer has been placed at D1 experimental area of J- PARC Muon Science Establishment (MUSE). Since February of 2014, the spectrometer has been used for the user programs of MUSE after a short commissioning period of one week. The data accumulation rate of the new spectrometer is 180 million positron events per hour (after taking the coincidence of two scintillators of telescopes) from a 20×20 mm sample for double-pulsed incoming muons

  15. Norm based design of fault detectors

    DEFF Research Database (Denmark)

    Rank, Mike Lind; Niemann, Hans Henrik

    1999-01-01

    The design of fault detectors for fault detection and isolation (FDI) in dynamic systems is considered in this paper from a norm based point of view. An analysis of norm based threshold selection is given based on different formulations of FDI problems. Both the nominal FDI problem as well as the...... uncertain FDI problem is considered. With reference to this analysis, a performance index based on norms of the involved transfer functions is given. A method for designing FDI filters which will minimize the performance index is also given....

  16. Ground-based LiDAR integration with avalanche control operations: target planning and assessment of control effectiveness

    Science.gov (United States)

    Deems, J. S.; LeWinter, A.; Gadomski, P. J.; Finnegan, D. C.

    2015-12-01

    The varying distribution of snow depth in avalanche starting zones exerts a strong influence on avalanche potential and character. Extreme depth changes over short distances are common, especially in wind-affected, above-treeline environments. Snow depth also affects the ease of avalanche triggering. Experience shows that avalanche reduction efforts are often more successful when targeting shallow trigger point areas near deeper slabs with explosives or ski cutting. We are exploring the use of high resolution snow depth and depth change maps from differential LiDAR scans to quantify loading patterns for use in both pre-control planning and in post-control assessment. We present results from our ongoing work at the Arapahoe Basin and Aspen Highlands ski areas in Colorado, USA, and from a new collaboration with the Colorado Department of Transportation. At Arapahoe Basin we have tested rapid snow depth product generation for use in planning placement of explosives for artificial avalanche triggering. At Aspen Highlands we have explored measurement of minimum disturbance depth from bootpacking. In a new application, we are assessing avalanche hazard reduction with new Gazex exploder arrays on Loveland and Berthoud Passes.

  17. Electroluminescence en avalanche des jonctions p-n a base de silicium et d'arseniure de gallium, et effet d'irradiation

    Science.gov (United States)

    Aboujja, Sidi

    2000-10-01

    Dans ce travail de these nous etudions l'electroluminescence (EL) des jonctions a base de silicium (Si) et d'arseniures de gallium (GaAs), polarisees en avalanche. Dans le cas des jonctions p-n a base de Si (semi-conducteur a gap indirect), la polarisation en direct est accompagnee d'une emission de lumiere dans l'infrarouge. Cette emission est due a la recombinaison des electrons-trous a travers le gap indirect appelee recombinaison interbande. La polarisation en avalanche est accompagnee d'une emission de lumiere dans le visible. Cette emission fait l'objet de controverses depuis sa decouverte en 1955. Il n'y a pas encore un accord definitif sur son origine. Une des causes du desaccord est la forme spectrale du signal qui apparaIt non reproductible. Souvent les spectres sont presentes sans correction par la reponse du systeme de detection. La plupart des modeles proposes pour expliquer cette emission en avalanche se basent sur les transitions entre la bande de conduction et la bande de valence appeles modeles interbandes. Pour verifier sa validite, nous avons expose les jonctions aux irradiations dans le but d'introduire des defauts dans la bande interdite et nous avons fait varier la temperature afin de changer le gap et la population des porteurs. Nous avons observe que l'EL dans le mode de polarisation directe chute suite aux irradiations et a la baisse de temperature, comme prevu. Mais l'EL en avalanche est insensible a ces deux perturbations. Par consequent nous avons rejete le mecanisme de recombinaison interbande. Pour expliquer l'emission en avalanche nous proposons des transitions entre d'autres niveaux excites appeles sous-bandes de conduction. La mesure de duree de vie qui s'est revelee courte suggere des transitions directes entre sous-bandes de conduction. La confrontation de la structure de bandes d'energie et l'experience nous a permis d'attribuer cette emission en avalanche a des transitions entre les sous-bandes de conduction Gamma1 et Gamma '1

  18. The performance of 2D array detectors for light sheet based fluorescence correlation spectroscopy.

    Science.gov (United States)

    Singh, Anand Pratap; Krieger, Jan Wolfgang; Buchholz, Jan; Charbon, Edoardo; Langowski, Jörg; Wohland, Thorsten

    2013-04-01

    Single plane illumination microscopy based fluorescence correlation spectroscopy (SPIM-FCS) is a new method for imaging FCS in 3D samples, providing diffusion coefficients, transport, flow velocities and concentrations in an imaging mode. SPIM-FCS records correlation functions over a whole plane in a sample, which requires array detectors for recording the fluorescence signal. Several types of image sensors are suitable for FCS. They differ in properties such as effective area per pixel, quantum efficiency, noise level and read-out speed. Here we compare the performance of several low light array detectors based on three different technologies: (1) Single-photon avalanche diode (SPAD) arrays, (2) passive-pixel electron multiplying charge coupled device (EMCCD) and (3) active-pixel scientific-grade complementary metal oxide semiconductor cameras (sCMOS). We discuss the influence of the detector characteristics on the effective FCS observation volume, and demonstrate that light sheet based SPIM-FCS provides absolute diffusion coefficients. This is verified by parallel measurements with confocal FCS, single particle tracking (SPT), and the determination of concentration gradients in space and time. While EMCCD cameras have a temporal resolution in the millisecond range, sCMOS cameras and SPAD arrays can extend the time resolution of SPIM-FCS down to 10 μs or lower. PMID:23571955

  19. Compact ion chamber based neutron detector

    Science.gov (United States)

    Derzon, Mark S.; Galambos, Paul C.; Renzi, Ronald F.

    2015-10-27

    A directional neutron detector has an ion chamber formed in a dielectric material; a signal electrode and a ground electrode formed in the ion chamber; a neutron absorbing material filling the ion chamber; readout circuitry which is electrically coupled to the signal and ground electrodes; and a signal processor electrically coupled to the readout circuitry. The ion chamber has a pair of substantially planar electrode surfaces. The chamber pressure of the neutron absorbing material is selected such that the reaction particle ion trail length for neutrons absorbed by the neutron absorbing material is equal to or less than the distance between the electrode surfaces. The signal processor is adapted to determine a path angle for each absorbed neutron based on the rise time of the corresponding pulse in a time-varying detector signal.

  20. Avoiding sensor blindness in Geiger mode avalanche photodiode arrays fabricated in a conventional CMOS process

    OpenAIRE

    Vilella Figueras, Eva; Diéguez Barrientos, Àngel

    2011-01-01

    The need to move forward in the knowledge of the subatomic world has stimulated the development of new particle colliders. However, the objectives of the next generation of colliders sets unprecedented challenges to the detector performance. The purpose of this contribution is to present a bidimensional array based on avalanche photodiodes operated in the Geiger mode to track high energy particles in future linear colliders. The bidimensional array can function in a gated mode to reduce the p...

  1. Sub-nanosecond time resolution detector based on APD for Synchrotron Radiation ultrafast experiments

    CERN Document Server

    Li, Zhen-jie; Liu, Peng; Wang, Shan-feng; Dong, Wei-wei; Zhou, Yang-fan

    2015-01-01

    Synchrotron radiation light sources produce intense beam of X-ray with ultra-short pulse and nanosecond period. This of-fers the opportunities for the time resolution experiments. Achieving higher counting rate and faster arriving time is diffi-cult for common detectors. But avalanche photodiodes (APD) based on silicon which have been commercially available1 with large active areas (e.g.10mmx10mm@ Perkin-Elmer Inc.) could satisfy the demands due to their good time resolution, low noise and large area.We investigate the high counting rate and nanosecond time resolution detector with APD. The detector's fast amplifier was designed with the gain of about 60dB (1000). The amplifier included with three stages RF-preamplifier using MAR6+ chip5 for the carefully controlling the circuit oscillation. Some measures have been taken for the preamplifiers good performance such as using resistance net between RF-preamplifier chip and the isolation of high voltage circuit from the preamplifier. The time resolution of the pr...

  2. Performance of Ultra-Fast Silicon Detectors

    CERN Document Server

    Cartiglia, N; Ely, S; Fadeyev, V; Galloway, Z; Marchetto, F; Mazza, G; Ngo, J; Obertino, M; Parker, C; Rivetti, A; Shumacher, D; Sadrozinski, H F-W; Seiden, A; Zatserklyaniy, A

    2013-01-01

    The development of Low-Gain Avalanche Detectors has opened up the possibility of manufacturing silicon detectors with signal larger than that of traditional sensors. In this paper we explore the timing performance of Low-Gain Avalanche Detectors, and in particular we demonstrate the possibility of obtaining ultra-fast silicon detector with time resolution of less than 20 picosecond.

  3. Advantages of gated silicon single photon detectors

    Science.gov (United States)

    Legré, Matthieu; Lunghi, Tommaso; Stucki, Damien; Zbinden, Hugo

    2013-05-01

    We present gated silicon single photon detectors based on two commercially available avalanche photodiodes (APDs) and one customised APD from ID Quantique SA. This customised APD is used in a commercially available device called id110. A brief comparison of the two commercial APDs is presented. Then, the charge persistence effect of all of those detectors that occurs just after a strong illumination is shown and discussed.

  4. Advanced active quenching circuits for single-photon avalanche photodiodes

    Science.gov (United States)

    Stipčević, M.; Christensen, B. G.; Kwiat, P. G.; Gauthier, D. J.

    2016-05-01

    Commercial photon-counting modules, often based on actively quenched solid-state avalanche photodiode sensors, are used in wide variety of applications. Manufacturers characterize their detectors by specifying a small set of parameters, such as detection efficiency, dead time, dark counts rate, afterpulsing probability and single photon arrival time resolution (jitter), however they usually do not specify the conditions under which these parameters are constant or present a sufficient description. In this work, we present an in-depth analysis of the active quenching process and identify intrinsic limitations and engineering challenges. Based on that, we investigate the range of validity of the typical parameters used by two commercial detectors. We identify an additional set of imperfections that must be specified in order to sufficiently characterize the behavior of single-photon counting detectors in realistic applications. The additional imperfections include rate-dependence of the dead time, jitter, detection delay shift, and "twilighting." Also, the temporal distribution of afterpulsing and various artifacts of the electronics are important. We find that these additional non-ideal behaviors can lead to unexpected effects or strong deterioration of the system's performance. Specifically, we discuss implications of these new findings in a few applications in which single-photon detectors play a major role: the security of a quantum cryptographic protocol, the quality of single-photon-based random number generators and a few other applications. Finally, we describe an example of an optimized avalanche quenching circuit for a high-rate quantum key distribution system based on time-bin entangled photons.

  5. New neutron detector based on Micromegas technology for ADS projects

    OpenAIRE

    Andriamonje, Samuel; Andriamonje, Gregory; Aune, Stephan; Ban, Gilles; Breaud, Stephane; Blandin, Christophe; Ferrer, Esther; Geslot, Benoit; Giganon, Arnaud; Giomataris, Ioannis; Jammes, Christian; Kadi, Yacine; Laborie, Philippe; Lecolley, Jean Francois; Pancin, Julien

    2006-01-01

    A new neutron detector based on Micromegas technology has been developed for the measurement of the simulated neutron spectrum in the ADS project. After the presentation of simulated neutron spectra obtained in the interaction of 140 MeV protons with the spallation target inside the TRIGA core, a full description of the new detector configuration is given. The advantage of this detector compared to conventional neutron flux detectors and the results obtained with the first prototype at the CE...

  6. Electric field distribution and simulation of avalanche formation due to the passage of heavy ions in a parallel grid avalanche counter

    Indian Academy of Sciences (India)

    D Kanjilal; S Saha

    2009-05-01

    Electric field distributions and their role in the formation of avalanche due to the passage of heavy ions in parallel grid avalanche type wire chamber detectors are evaluated using a Monte Carlo simulation. The relative merits and demerits of parallel and crossed wire grid configurations are studied. It is found that the crossed grid geometry has marginally higher gain at larger electric fields close to the avalanche region. The spatial uniformity of response in the two wire grid configurations is also compared.

  7. A new configuration of the Moxon-Rae detector based on Si detector

    International Nuclear Information System (INIS)

    A new Moxon-Rae detector configuration based on Si semiconductor detector was proposed in this paper. Three γ-ray sources, 137Cs, 60Co, and 24Na, were employed to make actual measurements using the new Moxon-Rae detector. The measured pulse height spectra and detection efficiencies were compared with the EGS4 simulated values. The results revealed that the proposed new configuration is indeed a successful method and specially a useful technique for higher energy γ-ray measurement

  8. Performance comparisons of contour-based corner detectors.

    Science.gov (United States)

    Awrangjeb, Mohammad; Lu, Guojun; Fraser, Clive S

    2012-09-01

    Corner detectors have many applications in computer vision and image identification and retrieval. Contour-based corner detectors directly or indirectly estimate a significance measure (e.g., curvature) on the points of a planar curve, and select the curvature extrema points as corners. While an extensive number of contour-based corner detectors have been proposed over the last four decades, there is no comparative study of recently proposed detectors. This paper is an attempt to fill this gap. The general framework of contour-based corner detection is presented, and two major issues-curve smoothing and curvature estimation, which have major impacts on the corner detection performance, are discussed. A number of promising detectors are compared using both automatic and manual evaluation systems on two large datasets. It is observed that while the detectors using indirect curvature estimation techniques are more robust, the detectors using direct curvature estimation techniques are faster. PMID:22645267

  9. Neuronal avalanches and brain plasticity

    Science.gov (United States)

    de Arcangelis, L.; Herrmann, H. J.; Perrone-Capano, C.

    2007-12-01

    Networks of living neurons exhibit an avalanche mode of activity, experimentally found in organotypic cultures. Moreover, experimental studies of morphology indicate that neurons develop a network of small-world-like connections, with the possibility of a very high connectivity degree. Here we discuss a recent model based on self-organized criticality, which consists of an electrical network with threshold firing and activity-dependent synapse strengths. The model is implemented on regular and small world lattices and on a scale-free network, the Apollonian network. The system exhibits an avalanche activity with a power law distribution of sizes and durations. The analysis of the power spectra of the electrical signal reproduces very robustly the power law behaviour with the exponent 0.8, experimentally measured in electroencephalogram (EEG) spectra. The exponents are found to be quite stable with respect to initial configurations and strength of plastic remodelling, indicating that universality holds for a wide class of neural network models.

  10. Positron camera with high-density avalanche chambers

    International Nuclear Information System (INIS)

    The results of an extensive investigation of the properties of high-density avalanche chambers (HIDAC) are presented. This study has been performed in order to optimize the layout of HIDAC detectors, since they are intended to be applied as position sensitive detectors for annihilation radiation in a positron emission tomograph being under construction. (author)

  11. A Stream Encryption Scheme with Both Key and Plaintext Avalanche Effects for Designing Chaos-Based Pseudorandom Number Generator with Application to Image Encryption

    Science.gov (United States)

    Han, Dandan; Min, Lequan; Chen, Guanrong

    Based on a stream encryption scheme with avalanche effect (SESAE), a stream encryption scheme with both key avalanche effect and plaintext avalanche effect (SESKPAE) is introduced. Using this scheme and an ideal 2d-word (d-segment) pseudorandom number generator (PRNG), a plaintext can be encrypted such that each bit of the ciphertext block has a change with the probable probability of (2d ‑ 1)/2d when any word of the key is changed or any bit of the plaintext is changed. To that end, a novel four-dimensional discrete chaotic system (4DDCS) is proposed. Combining the 4DDCS with a generalized synchronization (GS) theorem, a novel eight-dimensional discrete GS chaotic system (8DDGSCS) is constructed. Using the 8DDGSCS, a 216-word chaotic pseudorandom number generator (CPRNG) is designed. The keyspace of the 216-word CPRNG is larger than 21195. Then, the FIPS 140-2 test suit/generalized FIPS 140-2 test suit is used to test the randomness of the 1000-key streams consisting of 20000 bits generated by the 216-word CPRNG, the RC4 algorithm PRNG and the ZUC algorithm PRNG, respectively. The test results show that for the three PRNGs, there are 100%/98.9%, 99.9%/98.8%, 100%/97.9% key streams passing the tests, respectively. Furthermore, the SP800-22 test suite is used to test the randomness of four 100-key streams consisting of 1000000 bits generated by four PRNGs, respectively. The numerical results show that the randomness performances of the 216-word CPRNG is promising, showing that there are no significant correlations between the key streams and the perturbed key streams generated via the 216-word CPRNG. Finally, using the 216-word CPRNG and the SESKPAE to encrypt two gray-scale images, test results demonstrate that the 216-word CPRNG is able to generate both key avalanche effect and plaintext avalanche effect, which are similar to those generated via an ideal CPRNG, and performs better than other comparable schemes.

  12. High Sensitivity Indium Phosphide Based Avalanche Photodiode Focal Plane Arrays Project

    Data.gov (United States)

    National Aeronautics and Space Administration — nLight has demonstrated highly-uniform APD arrays based on the highly sensitive InGaAs/InP material system. These results provide great promise for achieving the...

  13. Room temperature single-photon detectors for high bit rate quantum key distribution

    Energy Technology Data Exchange (ETDEWEB)

    Comandar, L. C.; Patel, K. A. [Toshiba Research Europe Ltd., 208 Cambridge Science Park, Milton Road, Cambridge CB4 0GZ (United Kingdom); Engineering Department, Cambridge University, 9 J J Thomson Ave., Cambridge CB3 0FA (United Kingdom); Fröhlich, B., E-mail: bernd.frohlich@crl.toshiba.co.uk; Lucamarini, M.; Sharpe, A. W.; Dynes, J. F.; Yuan, Z. L.; Shields, A. J. [Toshiba Research Europe Ltd., 208 Cambridge Science Park, Milton Road, Cambridge CB4 0GZ (United Kingdom); Penty, R. V. [Engineering Department, Cambridge University, 9 J J Thomson Ave., Cambridge CB3 0FA (United Kingdom)

    2014-01-13

    We report room temperature operation of telecom wavelength single-photon detectors for high bit rate quantum key distribution (QKD). Room temperature operation is achieved using InGaAs avalanche photodiodes integrated with electronics based on the self-differencing technique that increases avalanche discrimination sensitivity. Despite using room temperature detectors, we demonstrate QKD with record secure bit rates over a range of fiber lengths (e.g., 1.26 Mbit/s over 50 km). Furthermore, our results indicate that operating the detectors at room temperature increases the secure bit rate for short distances.

  14. Advances in InGaAs/InP single-photon detector systems for quantum communication

    CERN Document Server

    Zhang, Jun; Zbinden, Hugo; Pan, Jian-Wei

    2015-01-01

    Single-photon detectors (SPDs) are the most sensitive instruments for light detection. In the near-infrared range, SPDs based on III-V compound semiconductor avalanche photodiodes have been extensively used during the past two decades for diverse applications due to their advantages in practicality including small size, low cost and easy operation. In the past decade, the rapid developments and increasing demands in quantum information science have served as key drivers to improve the device performance of single-photon avalanche diodes and to invent new avalanche quenching techniques. This Review aims to introduce the technology advances of InGaAs/InP single-photon detector systems in the telecom wavelengths and the relevant quantum communication applications, and particularly to highlight recent emerging techniques such as high-frequency gating at GHz rates and free-running operation using negative-feedback avalanche diodes. Future perspectives of both the devices and quenching techniques are summarized.

  15. Beam test results of a 15 ps timing system based on ultra-fast silicon detectors

    CERN Document Server

    Cartiglia, N; Sola, V; Arcidiacono, R; Cirio, R; Cenna, F; Ferrero, M; Monaco, V; Mulargia, R; Obertino, M; Ravera, F; Sacchi, R; Bellora, A; Durando, S; Mandurrino, M; Minafra, N; Fadeyev, V; Freeman, P; Galloway, Z; Gkougkousis, E; Grabas, H; Gruey, B; Labitan, C A; Losakul, R; McKinney-Martinez, F; Sadrozinski, H F -W; Seiden, A; Spencer, E; Wilder, M; Woods, N; Zatserklyaniy, A; Pellegrini, G; Hidalgo, S; Carulla, M; Flores, D; Merlos, A; Quirion, D; Cindro, V; Kramberger, G; Mandic, I; Mikuz, M; Zavrtanik, M

    2016-01-01

    In this paper we report on the timing resolution of the first production of 50 micro-meter thick Ultra-Fast Silicon Detectors (UFSD) as obtained in a beam test with pions of 180 GeV/c momentum. UFSD are based on the Low-Gain Avalanche Detectors (LGAD) design, employing n-on-p silicon sensors with internal charge multiplication due to the presence of a thin, low-resistivity diffusion layer below the junction. The UFSD used in this test belongs to the first production of thin (50 {\\mu}m) sensors, with an pad area of 1.4 mm2. The gain was measured to vary between 5 and 70 depending on the bias voltage. The experimental setup included three UFSD and a fast trigger consisting of a quartz bar readout by a SiPM. The timing resolution, determined comparing the time of arrival of the particle in one or more UFSD and the trigger counter, for single UFSD was measured to be 35 ps for a bias voltage of 200 V, and 26 ps for a bias voltage of 240 V, and for the combination of 3 UFSD to be 20 ps for a bias voltage of 200 V, ...

  16. Discrimination capability of avalanche counters detecting different ionizing particles

    International Nuclear Information System (INIS)

    The discrimination capability of avalanche counters to detect different ionizing particles has been studied using a 252Cf source. Pulse height, pulse-height resolution and timing properties have been measured as a function of the reduced applied voltage for parallel-plate and parallel-grid avalanche counters. At the highest applied voltages, space charge effects shift the pulse-height signal of the avalanche counter away from being linearly proportional to the stopping power of the detected particles and cause the pulse-height resolution to deteriorate. To optimize the avalanche counter capability, without loss of time resolution, it appears better to operate the detector at voltages well below the breakdown threshold. Measurements with 32S ions are also reported. (orig.)

  17. GaN-based PIN alpha particle detectors

    International Nuclear Information System (INIS)

    GaN-based PIN alpha particle detectors are studied in this article. The electrical properties of detectors have been investigated, such as current-voltage (I-V) and capacitance-voltage (C-V). The reverse current of all detectors is in nA range applied at 30 V, which is suitable for detector operation. The charge collection efficiency (CCE) is measured to be approximately 80% but the energy resolution is calculated to be about 40% mostly because the intrinsic layer is not sufficiently thick enough.

  18. New neutron detector based on Micromegas technology for ADS projects

    CERN Document Server

    Andriamonje, Samuel A; Aune, Stephan; Ban, Gilles; Breaud, Stephane; Blandin, Christophe; Ferrer, Esther; Geslot, Benoit; Giganon, Arnaud; Giomataris, Ioannis; Jammes, Christian; Kadi, Yacine; Laborie, Philippe; Lecolley, Jean Francois; Pancin, Julien; Riallot, Marc; Rosa, Roberto; Sarchiapone, Lucia; Steckmeyer, Jean Claude; Tillier, Joel

    2006-01-01

    A new neutron detector based on Micromegas technology has been developed for the measurement of the simulated neutron spectrum in the ADS project. After the presentation of simulated neutron spectra obtained in the interaction of 140 MeV protons with the spallation target inside the TRIGA core, a full description of the new detector configuration is given. The advantage of this detector compared to conventional neutron flux detectors and the results obtained with the first prototype at the CELINA 14 MeV neutron source facility at CEA-Cadarache are presented. The future developments of operational Piccolo-Micromegas for fast neutron reactors are also described.

  19. High-efficiency and low-jitter Silicon single-photon avalanche diodes based on nanophotonic absorption enhancement

    CERN Document Server

    Ma, Jian; Yu, Zongfu; Jiang, Xiao; Huo, Yijie; Zang, Kai; Zhang, Jun; Harris, James S; Jin, Ge; Zhang, Qiang; Pan, Jian-Wei

    2015-01-01

    Silicon single-photon avalanche diode (SPAD) is a core device for single-photon detection in the visible and the near-infrared range, and widely used in many applications. However, due to limits of the structure design and device fabrication for current silicon SPADs, the key parameters of detection befficiency and timing jitter are often forced to compromise. Here, we propose a nanostructured silicon SPAD, which achieves high detection efficiency with excellent timing jitter simultaneously over a broad spectral range. The optical and electric simulations show significant performance enhancement compared with conventional silicon SPAD devices. This nanostructured devices can be easily fabricated and thus well suited for practical applications.

  20. Studies of THGEM-based detector at low-pressure Hydrogen/Deuterium, for AT-TPC applications

    CERN Document Server

    Cortesi, Marco; Mittig, Wolfgang; Bazin, Daniel; Beceiro-Novo, Saul; Stolz, Andreas

    2015-01-01

    We study the performance of single- and double- THick Gas Electron Multiplier (THGEM) detectors in pure Hydrogen and Deuterium at low pressures, in the range of 100-450 Torr. The effect of the pressure on the maximum achievable gain, ion-back flow and long-term gain stability are investigated for single and double cascade detectors. In particular, it was found that maximum achievable gains above 10^4, from single-photoelectrons avalanche, can be achieved for pressures of 200 Torr and above; for lower pressure the gains are limited by avalanche-induced secondary effects to a values of around 103. The results of this work are relevant in the field of avalanche mechanism in low-pressure, low-mass noble gases, in particular for applications of THGEM end-cap readout for active-target Time Projection Chambers (TPC) in the field of nuclear physics and nuclear astrophysics.

  1. Studies of THGEM-based detector at low-pressure Hydrogen/Deuterium, for AT-TPC applications

    International Nuclear Information System (INIS)

    We study the performance of single- and double- THick Gas Electron Multiplier (THGEM) detectors in pure Hydrogen (H2) and Deuterium (D2) at low pressures, in the range of 100–450 torr. The effect of the pressure on the maximum achievable gain, ion-back flow and long-term gain stability are investigated for single and double cascade detectors. In particular, it was found that maximum achievable gains above 104, from single-photoelectrons avalanche, can be achieved for pressures of 200 torr and above; for lower pressure the gains are limited by avalanche-induced secondary effects to a values of around 103. The results of this work are relevant in the field of avalanche mechanism in low-pressure, low-mass noble gases, in particular for applications of THGEM end-cap readout for active-target Time Projection Chambers (TPC) in the field of nuclear physics and nuclear astrophysics

  2. Different hierarchy of avalanches observed in the Bak-Sneppen evolution model

    CERN Document Server

    Li, W

    2000-01-01

    We introduce a new quantity, average fitness, into the Bak-Sneppen evolution model. Through the new quantity, a different hierarchy of avalanches is observed. The gap equation, in terms of the average fitness, is presented to describe the self-organization of the model. It is found that the critical value of the average fitness can be exactly obtained. Based on the simulations, two critical exponents, avalanche distribution and avalanche dimension, of the new avalanches are given.

  3. Gas filled detectors

    International Nuclear Information System (INIS)

    The main types of gas filled nuclear detectors: ionization chambers, proportional counters, parallel-plate avalanche counters (PPAC) and microstrip detectors are described. New devices are shown. A description of the processes involved in such detectors is also given. (K.A.) 123 refs.; 25 figs.; 3 tabs

  4. Commercially available Geiger mode single-photon avalanche photodiode with a very low afterpulsing probability

    CERN Document Server

    Stipčević, Mario

    2015-01-01

    Afterpulsing is one of the main technological flaws present in photon counting detectors based on solid-state semiconductor avalanche photodiodes operated in Geiger mode. Level of afterpulsing depends mainly on type of the semiconductor, doping concentrations and temperature and presents an additional source of noise, along with dark counts. Unlike dark counts which appear randomly in time, aterpulses and are time-correlated with the previous detections. For measurements that rely on timing information afterpulsing can create fake signals and diminish the sensitivity. In this work we test a novel broadband sensitive APD that was designed for sub-Geiger avalanche gain operation. We find that this APD, which has a reach-through geometry typical of single-photon detection photodiodes, can also operate in Geiger mode with usable detection sensitivity and acceptable dark counts level while exhibiting uniquely low afterpulsing. The afterpulsing of tested samples was systematically less than 0.05 percent at 10V exce...

  5. A noble gas detector with electroluminescence readout based on an array of APDs

    International Nuclear Information System (INIS)

    We present the results of the operation of an array of avalanche photodiodes (APDs) for the readout of an electroluminescence detector. The detector contains 24 APDs with a pitch of 15 mm between them allowing energy and position measurements simultaneously. Measurements were performed in xenon (3.8 bar) and argon (4.8 bar) showing a good energy resolution of 5.3% FWHM at 60 keV in xenon and 9.4% in argon respectively. Following Monte Carlo studies the performance could be improved significantly by reducing the pitch between the sensors

  6. Production networks and failure avalanches

    CERN Document Server

    Weisbuch, G; Weisbuch, Gerard; Battiston, Stefano

    2005-01-01

    Although standard economics textbooks are seldom interested in production networks, modern economies are more and more based upon suppliers/customers interactions. One can consider entire sectors of the economy as generalised supply chains. We will take this view in the present paper and study under which conditions local failures to produce or simply to deliver can result in avalanches of shortage and bankruptcies across the network. We will show that a large class of models exhibit scale free distributions of production and wealth among firms and that metastable regions of high production are highly localised.

  7. The MCP-based vertex detector

    CERN Document Server

    Gevorkov, L G; CERN. Geneva; Laptev, V D; Patarakin, O O; Valiev, F F

    1992-01-01

    We discuss the possible application of large area microchannel plates (MCPs) as a basic Abstract: element of a vertex detector unit. Two types of basic modules : (MCP + Delay Line) and (MCP + Microstrips) are suggested. The proposal exploits unique MCPàs features i.e. fine granularity, high intrinsic gain, high counting rates, good performance in the presence of a magnetic field.

  8. Towards graphene-based detectors for dark matter directional detection

    CERN Document Server

    Wang, Shang-Yung

    2015-01-01

    Dark matter detectors with directional sensitivity have the capability to distinguish dark matter induced nuclear recoils from isotropic backgrounds, thus providing a smoking gun signature for dark matter in the Galactic halo. Here we propose a conceptually novel class of high directional sensitivity dark matter detectors utilizing graphene-based van der Waals heterostructures. The advantages over conventional low pressure gas time projection chamber-based directional detectors are discussed in detail. A practical implementation using graphene/hexagonal boron nitride and graphene/molybdenum disulfide heterostructures is presented together with an overwhelming amount of experimental evidence in strong support of its feasibility.

  9. Interplanetary space weather effects on Lunar Reconnaissance Orbiter avalanche photodiode performance

    Science.gov (United States)

    Clements, E. B.; Carlton, A. K.; Joyce, C. J.; Schwadron, N. A.; Spence, H. E.; Sun, X.; Cahoy, K.

    2016-05-01

    Space weather is a major concern for radiation-sensitive space systems, particularly for interplanetary missions, which operate outside of the protection of Earth's magnetic field. We examine and quantify the effects of space weather on silicon avalanche photodiodes (SiAPDs), which are used for interplanetary laser altimeters and communications systems and can be sensitive to even low levels of radiation (less than 50 cGy). While ground-based radiation testing has been performed on avalanche photodiode (APDs) for space missions, in-space measurements of SiAPD response to interplanetary space weather have not been previously reported. We compare noise data from the Lunar Reconnaissance Orbiter (LRO) Lunar Orbiter Laser Altimeter (LOLA) SiAPDs with radiation measurements from the onboard Cosmic Ray Telescope for the Effects of Radiation (CRaTER) instrument. We did not find any evidence to support radiation as the cause of changes in detector threshold voltage during radiation storms, both for transient detector noise and long-term average detector noise, suggesting that the approximately 1.3 cm thick shielding (a combination of titanium and beryllium) of the LOLA detectors is sufficient for SiAPDs on interplanetary missions with radiation environments similar to what the LRO experienced (559 cGy of radiation over 4 years).

  10. Room temperature particle detectors based on indium phosphide

    Energy Technology Data Exchange (ETDEWEB)

    Yatskiv, R., E-mail: yatskiv@ufe.c [Institute of Photonics and Electronics, Academy of Sciences of the Czech Republic, Chaberska 57, 18251 Praha 8 (Czech Republic); Grym, J.; Zdansky, K. [Institute of Photonics and Electronics, Academy of Sciences of the Czech Republic, Chaberska 57, 18251 Praha 8 (Czech Republic); Pekarek, L. [Institute of Photonics and Electronics, Academy of Sciences of the Czech Republic, Chaberska 57, 18251 Praha 8 (Czech Republic); Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 18221 Praha 8 (Czech Republic)

    2010-01-01

    A study of electrical properties and detection performance of particle detectors based on bulk InP and semiconducting LPE layers operated at room temperature is presented. Bulk detectors were fabricated on semi-insulating InP crystals grown by liquid-encapsulated Czochralski (LEC) technique. High purity InP layers of both n- and p-type conductivity were used to fabricate detector structures with p-n junction. The detection performance of particle detectors was measured by pulse-height spectra with alpha particles emitted from {sup 241}Am source at room temperature. Better noise properties were achieved for detectors with p-n junctions due to better quality contacts on p-type layers.

  11. Room temperature particle detectors based on indium phosphide

    Science.gov (United States)

    Yatskiv, R.; Grym, J.; Zdansky, K.; Pekarek, L.

    2010-01-01

    A study of electrical properties and detection performance of particle detectors based on bulk InP and semiconducting LPE layers operated at room temperature is presented. Bulk detectors were fabricated on semi-insulating InP crystals grown by liquid-encapsulated Czochralski (LEC) technique. High purity InP layers of both n- and p-type conductivity were used to fabricate detector structures with p-n junction. The detection performance of particle detectors was measured by pulse-height spectra with alpha particles emitted from 241Am source at room temperature. Better noise properties were achieved for detectors with p-n junctions due to better quality contacts on p-type layers.

  12. Room temperature particle detectors based on indium phosphide

    International Nuclear Information System (INIS)

    A study of electrical properties and detection performance of particle detectors based on bulk InP and semiconducting LPE layers operated at room temperature is presented. Bulk detectors were fabricated on semi-insulating InP crystals grown by liquid-encapsulated Czochralski (LEC) technique. High purity InP layers of both n- and p-type conductivity were used to fabricate detector structures with p-n junction. The detection performance of particle detectors was measured by pulse-height spectra with alpha particles emitted from 241Am source at room temperature. Better noise properties were achieved for detectors with p-n junctions due to better quality contacts on p-type layers.

  13. A compensated fission detector based on photovoltaic cells

    Energy Technology Data Exchange (ETDEWEB)

    Petit, M. [CEA/DAM Ile-de-France, DPTA/Service de Physique Nucleaire, BP 12, 91680 Bruyeres-le-Chatel (France); Ethvignot, T. [CEA/DAM Ile-de-France, DPTA/Service de Physique Nucleaire, BP 12, 91680 Bruyeres-le-Chatel (France); Granier, T. [CEA/DAM Ile-de-France, DPTA/Service de Physique Nucleaire, BP 12, 91680 Bruyeres-le-Chatel (France)]. E-mail: thierry.granier@cea.fr; Haight, R.C. [LANSCE-3, Los Alamos National Laboratory, MS H855, Los Alamos, NM 87545 (United States); O' Donnell, J.M. [LANSCE-3, Los Alamos National Laboratory, MS H855, Los Alamos, NM 87545 (United States); Rochman, D. [LANSCE-3, Los Alamos National Laboratory, MS H855, Los Alamos, NM 87545 (United States); Wender, S.A. [LANSCE-3, Los Alamos National Laboratory, MS H855, Los Alamos, NM 87545 (United States); Bond, E.M. [C-INC, Los Alamos National Laboratory, MS J514, Los Alamos, NM 87545 (United States); Bredeweg, T.A. [C-INC, Los Alamos National Laboratory, MS J514, Los Alamos, NM 87545 (United States); Vieira, D.J. [C-INC, Los Alamos National Laboratory, MS J514, Los Alamos, NM 87545 (United States); Wilhelmy, J.B. [C-INC, Los Alamos National Laboratory, MS J514, Los Alamos, NM 87545 (United States); Danon, Y. [Rensselaer Polytechnic Institute, Troy, NY 12180 (United States)

    2005-12-01

    Standard techniques of event-by-event detection of fission may fail when operated in high {gamma}-ray or particle radiation environments. This is the case within the 800MeV proton-driven lead slowing-down neutron spectrometer at LANSCE where standard fission detectors are found to be inoperable for microseconds to milliseconds after each proton pulse. To overcome this problem, a simple fission fragment detector based on compensated photovoltaic cells has been developed. The compensated detector has lower susceptibility to the strong {gamma}-flash and can recover much faster than an uncompensated detector. This detector is well adapted to applications involving the detection of fission in regions where high intensity {gamma}-ray and/or particle radiation fields exist.

  14. A compensated fission detector based on photovoltaic cells

    Science.gov (United States)

    Petit, M.; Ethvignot, T.; Granier, T.; Haight, R. C.; O'Donnell, J. M.; Rochman, D.; Wender, S. A.; Bond, E. M.; Bredeweg, T. A.; Vieira, D. J.; Wilhelmy, J. B.; Danon, Y.

    2005-12-01

    Standard techniques of event-by-event detection of fission may fail when operated in high γ-ray or particle radiation environments. This is the case within the 800 MeV proton-driven lead slowing-down neutron spectrometer at LANSCE where standard fission detectors are found to be inoperable for microseconds to milliseconds after each proton pulse. To overcome this problem, a simple fission fragment detector based on compensated photovoltaic cells has been developed. The compensated detector has lower susceptibility to the strong γ-flash and can recover much faster than an uncompensated detector. This detector is well adapted to applications involving the detection of fission in regions where high intensity γ-ray and/or particle radiation fields exist.

  15. A passive FPAA based RF scatter meteor detector

    CERN Document Server

    Popowicz, Adam; Bernacki, Krzysztof; Fietkiewicz, Karol

    2015-01-01

    In the article we present a hardware meteor detector. The detection principle is based on the electromagnetic wave reflection from the ionized meteor trail in the atmosphere. The detector uses the ANADIGM field programmable analogue array (FPAA), which is an attractive alternative for a typically used detecting equipment - a PC computer with dedicated software. We implement an analog signal path using most of available FPAA resources to obtain precise audio signal detection. Our new detector was verified in collaboration with the Polish Fireball Network - the organization which monitors meteor activity in Poland. When compared with currently used signal processing PC software employing real radio meteor scatter signals, our low-cost detector proved to be more precise and reliable. Due to its cost and efficiency superiority over the current solution, the presented module is going to be implemented in the planned distributed detectors system.

  16. Modeling and monitoring avalanches caused by rain-on-snow events

    Science.gov (United States)

    Havens, S.; Marshall, H. P.; Trisca, G. O.; Johnson, J. B.; Nicholson, B.

    2014-12-01

    Direct-action avalanches occur during large storm cycles in mountainous regions, when stresses on the snowpack increase rapidly due to the load of new snow and outpace snow strengthening due to compaction. If temperatures rise above freezing during the storm and snowfall turns to rain, the near-surface snow undergoes rapid densification caused by the introduction of liquid water. This shock to the snowpack, if stability is near critical, can cause widespread immediate avalanching due to the large induced strain rates in the slab, followed by secondary delayed avalanches due to both the increased load as well as water percolation to the depth of a weak layer. We use the semi-empirical SNOow Slope Stability model (SNOSS) to estimate the evolution of stability prior to large avalanches during rain-on-snow events on Highway 21 north of Boise, Idaho. We have continuously monitored avalanche activity using arrays of infrasound sensors in the avalanche-prone section of HW21 near Stanley, in collaboration with the Idaho Transportation Department's avalanche forecasting program. The autonomous infrasound avalanche monitoring system provides accurate timing of avalanche events, in addition to capturing avalanche dynamics during some major releases adjacent to the array. Due to the remote location and low winter traffic volume, the highway is typically closed for multiple days during major avalanche cycles. Many major avalanches typically release naturally and reach the road, but due the complex terrain and poor visibility, manual observations are often not possible until several days later. Since most avalanche programs typically use explosives on a regular basis to control slope stability, the infrasound record of avalanche activity we have recorded on HW21 provides a unique opportunity to study large naturally triggered avalanches. We use a first-order physically based stability model to estimate the importance of precipitation phase, amount, and rate during major rain

  17. Modelisation de photodetecteurs a base de matrices de diodes avalanche monophotoniques pour tomographie d'emission par positrons

    Science.gov (United States)

    Corbeil Therrien, Audrey

    La tomographie d'emission par positrons (TEP) est un outil precieux en recherche preclinique et pour le diagnostic medical. Cette technique permet d'obtenir une image quantitative de fonctions metaboliques specifiques par la detection de photons d'annihilation. La detection des ces photons se fait a l'aide de deux composantes. D'abord, un scintillateur convertit l'energie du photon 511 keV en photons du spectre visible. Ensuite, un photodetecteur convertit l'energie lumineuse en signal electrique. Recemment, les photodiodes avalanche monophotoniques (PAMP) disposees en matrice suscitent beaucoup d'interet pour la TEP. Ces matrices forment des detecteurs sensibles, robustes, compacts et avec une resolution en temps hors pair. Ces qualites en font un photodetecteur prometteur pour la TEP, mais il faut optimiser les parametres de la matrice et de l'electronique de lecture afin d'atteindre les performances optimales pour la TEP. L'optimisation de la matrice devient rapidement une operation difficile, car les differents parametres interagissent de maniere complexe avec les processus d'avalanche et de generation de bruit. Enfin, l'electronique de lecture pour les matrices de PAMP demeure encore rudimentaire et il serait profitable d'analyser differentes strategies de lecture. Pour repondre a cette question, la solution la plus economique est d'utiliser un simulateur pour converger vers la configuration donnant les meilleures performances. Les travaux de ce memoire presentent le developpement d'un tel simulateur. Celui-ci modelise le comportement d'une matrice de PAMP en se basant sur les equations de physique des semiconducteurs et des modeles probabilistes. Il inclut les trois principales sources de bruit, soit le bruit thermique, les declenchements intempestifs correles et la diaphonie optique. Le simulateur permet aussi de tester et de comparer de nouvelles approches pour l'electronique de lecture plus adaptees a ce type de detecteur. Au final, le simulateur vise a

  18. A detector insert based on continuous scintillators for hybrid MR–PET imaging of the human brain

    Energy Technology Data Exchange (ETDEWEB)

    Rato Mendes, P., E-mail: pedro.rato@ciemat.es [CIEMAT, Avenida Complutense 40, 28040 Madrid (Spain); Cuerdo, R.; Sarasola, I.; García de Acilu, P.; Navarrete, J.; Vela, O.; Oller, J.C.; Cela, J.M. [CIEMAT, Avenida Complutense 40, 28040 Madrid (Spain); Núñez, L.; Pastrana, M. [Hospital Universitario Puerta de Hierro Majadahonda, Manuel de Falla 1, 28222 Majadahonda (Spain); Romero, L.; Willmott, C. [CIEMAT, Avenida Complutense 40, 28040 Madrid (Spain)

    2013-02-21

    We are developing a positron emission tomography (PET) insert for existing magnetic resonance (MR) equipment, aiming at hybrid MR–PET imaging. Our detector block design is based on trapezoid-shaped LYSO:Ce monolithic scintillators coupled to magnetically compatible Hamamatsu S8550-02 silicon avalanche photodiode (APD) matrices with a dedicated ASIC front-end readout from GammaMedica-Ideas (Fornebu, Norway). The detectors are position sensitive, capable of determining the incidence point of 511 keV gammas with an intrinsic spatial resolution on the order of 2 mm by means of supervised learning neural-network (NN) algorithms. These algorithms, apart from providing continuous coordinates, are also intrinsically corrected for depth of interaction effects and thus parallax-free. Recently we have implemented an advanced prototype featuring two heads with four detector blocks each and final front-end and readout electronics, improving the spatial resolution of reconstructed point source images down to 1.7 mm full width at half maximum (FWHM). Presently we are carrying out operational tests of components and systems under magnetic fields using a 3 T MR scanner. In this paper we present a description of our project, a summary of the results obtained with laboratory prototypes, and the strategy to build and install the complete system at the nuclear medicine department of a collaborating hospital.

  19. Particle detectors based on semiconducting InP epitaxial layers

    OpenAIRE

    Yatskiv, R. (Roman); Grym, J.; Žďánský, K. (Karel)

    2011-01-01

    In this work, we present study of electrical properties and detection performance of two types of InP detector structures: (i) with p-n-junction and (ii) with Schottky contact prepared on high purity p-type InP. The p-n junction detectors were based on a high purity InP:Pr layers of both n- and p- type conductivity with carrier concentration on the order of 1014 cm-3 grown on Sn doped n-type substrate. Schottky barrier detectors were prepared by vacuum evaporation of Pd on high purity p-type ...

  20. Selective detector of cosmic particles based on diamond sensitive elements

    Science.gov (United States)

    Altukhov, A. A.; Zaharchenko, K. V.; Kolyubin, V. A.; Lvov, S. A.; Nedosekin, P. G.; Tyurin, E. M.; Ibragimov, R. F.; Kadilin, V. V.; Nikolaev, I. V.

    2016-02-01

    The article describes the device for selective registration of electrons, protons and heavy ions fluxes from the solar and galactic cosmic rays in the twelve energy ranges, built on a base of diamond detector. The use of the diamond detectors allowed for the creation a device for registration of cosmic particles fluxes at the external spacecraft surface with the resource not less than 20 years. Selective detector is aimed for continuous monitoring of radiation situation on board the spacecrafts, in order to predict the residual life of their work and prompt measures to actively protect the spacecraft when the flow of cosmic particles is sharply increased.

  1. The STACEE-32 Ground Based Gamma-ray Detector

    CERN Document Server

    Hanna, D S; Boone, L M; Chantell, M C; Conner, Z; Covault, C E; Dragovan, M; Fortin, P; Gregorich, D T; Hinton, J A; Mukherjee, R; Ong, R A; Oser, S; Ragan, K; Scalzo, R A; Schütte, D R; Theoret, C G; Tümer, T O; Williams, D A; Zweerink, J A

    2002-01-01

    We describe the design and performance of the Solar Tower Atmospheric Cherenkov Effect Experiment detector in its initial configuration (STACEE-32). STACEE is a new ground-based gamma ray detector using the atmospheric Cherenkov technique. In STACEE, the heliostats of a solar energy research array are used to collect and focus the Cherenkov photons produced in gamma-ray induced air showers. The large Cherenkov photon collection area of STACEE results in a gamma-ray energy threshold below that of previous detectors.

  2. Scintillation Particle Detectors Based on Plastic Optical Fibres and Microfluidics

    CERN Document Server

    Mapelli, Alessandro; Renaud, Philippe

    2011-01-01

    This thesis presents the design, development, and experimental validation of two types of scintillation particle detectors with high spatial resolution. The first one is based on the well established scintillating fibre technology. It will complement the ATLAS (A Toroidal Large ApparatuS) detector at the CERN Large Hadron Collider (LHC). The second detector consists in a microfabricated device used to demonstrate the principle of operation of a novel type of scintillation detector based on microfluidics. The first part of the thesis presents the work performed on a scintillating fibre tracking system for the ATLAS experiment. It will measure the trajectory of protons elastically scattered at very small angles to determine the absolute luminosity of the CERN LHC collider at the ATLAS interaction point. The luminosity of an accelerator characterizes its performance. It is a process-independent parameter that is completely determined by the properties of the colliding beams and it relates the cross section of a ...

  3. Novel Boron Based Multilayer Thermal Neutron Detector

    CERN Document Server

    SCHIEBER, M

    2010-01-01

    The detector contains four or more layers of natural Boron absorbing thermal neutrons. Thickness of a layer is 0.4 - 1.2 mg/cm2. The layers are deposited on one or on both sides of a metal surface used as contacts. Between the absorbing layers there are gas-filled gaps 3 - 6 mm thick. Electric field of 100 - 200 V/cm is applied to the gas-filled gaps. Natural Boron contains almost 20% of 10B isotope. When atoms of 10B capture a thermal neutron, nuclear reaction occurs, as a result of which two heavy particles - alpha particle and ion 7Li - from the thin absorber layer are emitted in opposing sides. One of the two particles penetrates into gas-filled gap between Boron layers and ionizes the gas. An impulse of electric current is created in the gas-filled gap actuated by the applied electric field. The impulse is registered by an electronic circuit. We have made and tested detectors containing from two to sixteen layers of natural Boron with an efficiency of thermal neutron registration from 2.9% to 12.5% accor...

  4. Investigation of avalanche photodiodes radiation hardness for baryonic matter studies

    International Nuclear Information System (INIS)

    Modern avalanche photodiodes (APDs) with high gain are good device candidates for light readout from detectors applied in relativistic heavy-ion collision experiments. The results of the investigations of the APDs properties from Zecotek, Ketek, and Hamamatsu manufacturers after irradiation using secondary neutrons from U120M cyclotron facility at NPI of ASCR in Rez are presented. The results of the investigations can be used for the design of the detectors for the experiments at NICA and FAIR

  5. Investigation of avalanche photodiodes radiation hardness for baryonic matter studies

    CERN Document Server

    Kushpil, V; Ladygin, V P; Kugler, A; Kushpil, S; Svoboda, O; Tlustý, P

    2015-01-01

    Modern avalanche photodiodes (APDs) with high gain are good device candidates for light readout from detectors applied in relativistic heavy ion collisions experiments. The results of the investigations of the APDs properties from Zecotek, Ketek and Hamamatsu manufacturers after irradiation using secondary neutrons from cyclotron facility U120M at NPI of ASCR in \\v{R}e\\v{z} are presented. The results of the investigations can be used for the design of the detectors for the experiments at NICA and FAIR.

  6. 高分辨率高效率三维正电子发射断层扫描成像探测器研发%High Spatial Resolution and High Sensitivity Three Dimensional PET Detector Development with Position-sensitive Avalanche Photodiode and Silicon Photomultiplier Readout

    Institute of Scientific and Technical Information of China (English)

    李成; 邝忠华; 都军伟; 白晓薇; Simon R. Cherry; 梁栋; 刘新; 郑海荣; 杨永峰

    2016-01-01

    Small animal positron emission tomography (PET) is a well-established imaging modality in preclinical biomedical research. But depth encoding detectors are required to simultaneously achieve high spatial resolution and high sensitivity for a small animal PET scanner. In this work, we evaluated several dual-ended readout detector modules using lutetium oxyorthosilicate (LSO) arrays with crystal sizes ranging from 0.70 mm to 0.44 mm, read out by either position-sensitive avalanche photodiodes (PSAPDs) or position-sensitive silicon photomultipliers (PS-SiPMs). A new type of PS-SiPM was developed recently and was evaluated for the ifrst time in this work. First, the signal-to-noise ratio (SNR) of both PSAPDs and PS-SiPMs was measured, and then the lfood histograms, energy resolution and depth of interaction (DOI) resolution of dual-ended readout detector modules by using both PSAPDs and PS-SiPMs were measured. The PSAPD has much better SNR as compared with PS-SiPM. For the detectors using PSAPDs, crystals as small as 0.44 mm can be resolved and a DOI resolution as good as 1.4 mm was obtained. For the detectors using PS-SiPMs, 0.7 mm crystals can be resolved and a DOI resolution of 2.9 mm was obtained. Based on the results of the lfood histograms, energy resolution and DOI resolution the detector modules using PSAPD are better than those using PS-SiPMs. The SNR of the PS-SiPM would need to be improved to resolve even smaller crystals and the number of SiPM cells also need to be increased to reduce the saturation effect to improve the DOI resolution. The performance of the three dimensional depth encoding PET detectors using PSAPDs is much better because the SNR of PSAPD is much higher than PS-SiPM. In the future, high resolution depth encoding PET detectors will be developed by using both new PS-SiPMs and SiPM arrays.%小动物正电子发射断层扫描成像(Positron Emission Tomography,PET)是临床前生物医学研究的重要工具,但小动物 PET要同时

  7. Central Tracking Detector Based on Scintillating Fibres

    CERN Multimedia

    2002-01-01

    Scintillating fibres form a reasonable compromise for central tracking detectors in terms of price, resolution, response time, occupancy and heat production. \\\\ \\\\ New fluorescents with large Stokes shifts have been produced, capable of working without wavelength shifters. Coherent multibundles have been developed to achieve high packing fractions. Small segments of tracker shell have been assembled and beam tests have confirmed expectations on spatial resolution. An opto-electronic delay line has been designed to delay the track patterns and enable coincidences with a first level trigger. Replacement of the conventional phosphor screen anode with a Si pixel chip is achieved. This tube is called ISPA-tube and has already been operated in beam tests with a scintillating fibres tracker. \\\\ \\\\ The aim of the proposal is to improve hit densities for small diameter fibres by increasing the fraction of trapped light, by reducing absorption and reflection losses, by reflecting light at the free fibre end, and by inc...

  8. Observational Selection Effects with Ground-based Gravitational Wave Detectors

    CERN Document Server

    Chen, Hsin-Yu; Vitale, Salvatore; Holz, Daniel E; Katsavounidis, Erik

    2016-01-01

    Ground-based interferometers are not perfectly all-sky instruments, and it is important to account for their behavior when considering the distribution of detected events. In particular, the LIGO detectors are most sensitive to sources above North America and the Indian Ocean and, as the Earth rotates, the sensitive regions are swept across the sky. However, because the detectors do not acquire data uniformly over time, there is a net bias on detectable sources' right ascensions. Both LIGO detectors preferentially collect data during their local night; it is more than twice as likely to be local midnight than noon when both detectors are operating. We discuss these selection effects and how they impact LIGO's observations and electromagnetic follow-up. Beyond galactic foregrounds associated with seasonal variations, we find that equatorial observatories can access over $80\\%$ of the localization probability, while mid-latitudes will access closer to $70\\%$. Facilities located near the two LIGO sites can obser...

  9. Particle detectors based on semiconducting InP epitaxial layers

    Science.gov (United States)

    Yatskiv, R.; Grym, J.; Zdansky, K.

    2011-01-01

    A study of electrical properties and detection performance of two types of Indium Phosphide detector structures was performed: (i) with p-n-junction and (ii) with Schottky contact prepared on high purity p-type InP. The p-n junction detectors were based on a high purity InP:Pr layers of both n- and p- type conductivity with carrier concentration on the order of 1014 cm-3 grown on Sn doped n-type substrate. Schottky barrier detectors were prepared by vacuum evaporation of Pd on high purity p-type epitaxial layer grown on Mn doped p-type substrate. The detection performance of particle detectors was measured by pulse-height spectra with alpha particles emitted from 241Am source at room temperature.

  10. Particle detectors based on semiconducting InP epitaxial layers

    Energy Technology Data Exchange (ETDEWEB)

    Yatskiv, R; Grym, J; Zdansky, K, E-mail: yatskiv@ufe.cz [Institute of Photonics and Electronics, Academy of Sciences of the Czech Republic, Chaberska 57, 18251 Praha 8 (Czech Republic)

    2011-01-15

    A study of electrical properties and detection performance of two types of Indium Phosphide detector structures was performed: (i) with p-n-junction and (ii) with Schottky contact prepared on high purity p-type InP. The p-n junction detectors were based on a high purity InP:Pr layers of both n- and p- type conductivity with carrier concentration on the order of 10{sup 14} cm{sup -3} grown on Sn doped n-type substrate. Schottky barrier detectors were prepared by vacuum evaporation of Pd on high purity p-type epitaxial layer grown on Mn doped p-type substrate. The detection performance of particle detectors was measured by pulse-height spectra with alpha particles emitted from {sup 241}Am source at room temperature.

  11. Particle detectors based on semiconducting InP epitaxial layers

    International Nuclear Information System (INIS)

    A study of electrical properties and detection performance of two types of Indium Phosphide detector structures was performed: (i) with p-n-junction and (ii) with Schottky contact prepared on high purity p-type InP. The p-n junction detectors were based on a high purity InP:Pr layers of both n- and p- type conductivity with carrier concentration on the order of 1014 cm-3 grown on Sn doped n-type substrate. Schottky barrier detectors were prepared by vacuum evaporation of Pd on high purity p-type epitaxial layer grown on Mn doped p-type substrate. The detection performance of particle detectors was measured by pulse-height spectra with alpha particles emitted from 241Am source at room temperature.

  12. Simulations of SiPM based scintillation detector for PANDA

    International Nuclear Information System (INIS)

    The Facility for Antiproton and Ion Research (FAIR) is a future project at GSI which will extend hadron physics studies up to the charm meson region using antiproton beams together with a state-of-the-art PANDA (acronym for antiProton ANnihilation at DArmstadt) detector. The physics aim, in a broader sense, is to address the fundamental problems of hadron physics and aspects of Quantum Chromo Dynamics (QCD) at low energies. The proposed work in India will consist of several parts: (i) development of a SiPM based scintillation tile hodoscope for TOF information, (ii) development of a luminosity detector (silicon strip detector), and (iii) simulation studies of these detectors design as well as physics case studies. The present paper reports the initial simulation studies that have been started at Nuclear Physics Division (NPD), BARC, on the silicon photomultiplier(SiPM) based fast scintillation detector (SciTil). The hardware development activities on this SciTil detector, that are also going on in parallel at NPD, has been reported in an another contribution to this proceedings

  13. Characteristics of avalanche accidents and a overview of avalanche equipment

    Directory of Open Access Journals (Sweden)

    Mateusz Biela

    2015-12-01

    Full Text Available Avalanches are one of the most spectacular phenomena which may occur in the mountains. Unfortunately they are often caused by humans and pose for him a big danger. In the Polish Tatras alone they represent 18% of all causes of death among 1996-2013. One fourth of the people caught by an avalanche dies, and their chances of survival depends on the depth of burial, burial time, the presence of an air pocket and the degree of injuries. The most common cause of death is asphyxiation, the next is injuries and hypothermia is the rarest cause of death. The fate of the buried people depends on their equipment such as avalanche transceiver, ABS backpack and AvaLung, and also from the equipment of the people who are seeking (avalanche probes, avalanche transceiver and shovels, which has been proven in practice and research.

  14. A Noble Gas Detector with Electroluminescence Readout based on an Array of APDs

    CERN Document Server

    Bourguille, B; Gil-Botella, I; Lux, T; Palomares, C; Sanchez, F; Santorelli, R

    2015-01-01

    We present the results of the operation of an array of avalanche photodiodes (APDs) for the readout of an electroluminescence detector. The detector contains 24 APDs with a pitch of 15 mm between them allowing energy and position measurements simultaneously. Measurements were performed in xenon (3.8 bar) and argon (4.8 bar) showing a good energy resolution of 5.3% FWHM at 60 keV in xenon and 9.4% in argon respectively. In X-ray energies of 13 could be clearly separated from the pedestals indicating that this kind of technology might be also interesting for dark matter detectors. Following Monte Carlo studies the performance could be improved significantly by reducing the pitch between the sensors.

  15. Cellular automaton-based position sensitive detector equalization

    Energy Technology Data Exchange (ETDEWEB)

    Ferrando, Nestor [Grupo de Diseno de Sistemas Digitales, Instituto de Aplicaciones de las Tecnologias de la Informacion y de las Comunicaciones Avanzadas, Universidad Politecnica de Valencia, Camino de Vera s/n, 46022 Valencia (Spain)], E-mail: nesferjo@upvnet.upv.es; Herrero, V.; Cerda, J.; Lerche, C.W.; Colom, R.J.; Gadea, R.; Martinez, J.D.; Monzo, J.M.; Mateo, F.; Sebastia, A.; Benlloch, J.M. [Grupo de Diseno de Sistemas Digitales, Instituto de Aplicaciones de las Tecnologias de la Informacion y de las Comunicaciones Avanzadas, Universidad Politecnica de Valencia, Camino de Vera s/n, 46022 Valencia (Spain)

    2009-06-01

    Indirect position detectors based on scintillator crystals lack of spacial uniformity in their response. This happens due to crystal inhomogeneities and gain differences among the photomultiplier anodes. In order to solve this, PESIC, an integrated front-end for multianode photomultiplier based nuclear imaging devices was created. One of its main features is the digitally programmable gain adjustment for every photomultiplier output. On another front, cellular automata have been proved to be a useful method for dynamic system modeling. In this paper, a cellular automaton which emulates the behavior of the scintillator crystal, the photomultiplier and the front-end is introduced. Thanks to this model, an automatic energy-based calibration of the detector can be done by configuring the cellular automaton with experimental data and making it evolve up to an stable state. This can be useful as a precalibration method of the detector.

  16. Forensic Analysis of the May 2014 West Salt Creek Rock Avalanche in Western Colorado

    Science.gov (United States)

    Coe, J. A.; Baum, R. L.; Allstadt, K.; Kochevar, B. F.; Schmitt, R. G.; Morgan, M. L.; White, J. L.; Stratton, B. T.; Hayashi, T. A.; Kean, J. W.

    2015-12-01

    The rain-on-snow induced West Salt Creek rock avalanche occurred on May 25, 2014 on the northern flank of Grand Mesa. The avalanche was rare for the contiguous U.S. because of its large size (59 M m3) and high mobility (Length/Height=7.2). To understand the avalanche failure sequence, mechanisms, and mobility, we conducted a forensic analysis using large-scale (1:1000) structural mapping and seismic data. We used high-resolution, Unmanned Aircraft System (UAS) imagery as a base for our field mapping and analyzed seismic data from 22 broadband stations (distances <656 km) and one short-period network. We inverted broadband data to derive a time series of forces that the avalanche exerted on the earth and tracked these forces using curves in the avalanche path. Our results revealed that the rock avalanche was a cascade of landslide events, rather than a single massive failure. The sequence began with a landslide/debris flow that started about 10 hours before the main avalanche. The main avalanche lasted just over 3 minutes and traveled at average velocities ranging from 15 to 36 m/s. For at least two hours after the avalanche ceased movement, a central, hummock-rich, strike-slip bound core continued to move slowly. Following movement of the core, numerous shallow landslides, rock slides, and rock falls created new structures and modified topography. Mobility of the main avalanche and central core were likely enhanced by valley floor material that liquefied from undrained loading by the overriding avalanche. Although the base was likely at least partially liquefied, our mapping indicates that the overriding avalanche internally deformed predominantly by sliding along discrete shear surfaces in material that was nearly dry and had substantial frictional strength. These results indicate that the West Salt Creek avalanche, and probably other long-traveled avalanches, could be modeled as two layers: a liquefied basal layer; and a thicker and stronger overriding layer.

  17. Particle and radiation detectors based on diamond

    Energy Technology Data Exchange (ETDEWEB)

    Bergonzo, P.; Tromson, D.; Mer, C.; Guizard, B.; Foulon, F.; Brambilla, A. [LIST/DIMRI/SIAR, CEA/Saclay, Gif-sur-Yvette (France)

    2001-05-16

    CVD diamond is a remarkable material for the fabrication of particle and photon radiation detectors. The improvement of the electronic properties of the material has been under intensive investigations and led to the development of a few applications that are addressing specific industrial needs. In particular, we have used diamond layers for industrial applications where it exhibits attractive characteristics as compared with other materials: e.g., radiation and corrosion hardness for {alpha}-counters or high gamma-meters at high fluxes; high transparency to low energy X-rays for synchrotron beam line monitoring devices, etc. These specific properties can motivate the use of diamond even though the detection properties remain relatively poor. Indeed, one inherent problem with diamond is the presence of defect levels that are altering the detection characteristics. These are observed in all CVD materials but also in very high quality natural diamonds. They result in unstable responses and carrier losses. Also, it has been observed that high sensitivities may result from the progressive filling of deep levels, e.g. pumping effects, with a detrimental effect on the stability and the response time. Also, the polycrystalline nature is somewhat detrimental as it induces significant non-uniformities of the device response with respect to the position of interaction. We have investigated these features by imaging the response of CVD diamond using a micrometer size focused X-ray beam. The comparison with the grain structure showed that it has a strong influence on the field distribution. We present here recent developments studied at CEA in Saclay for the optimisation of the material with respect to the specific requirements of several applications. They include radiation hard counters; X-ray intensity, shape and beam position monitors, solar blind photodetectors, and high dose rate gamma-meters. (orig.)

  18. Statistical analyses support power law distributions found in neuronal avalanches.

    Directory of Open Access Journals (Sweden)

    Andreas Klaus

    Full Text Available The size distribution of neuronal avalanches in cortical networks has been reported to follow a power law distribution with exponent close to -1.5, which is a reflection of long-range spatial correlations in spontaneous neuronal activity. However, identifying power law scaling in empirical data can be difficult and sometimes controversial. In the present study, we tested the power law hypothesis for neuronal avalanches by using more stringent statistical analyses. In particular, we performed the following steps: (i analysis of finite-size scaling to identify scale-free dynamics in neuronal avalanches, (ii model parameter estimation to determine the specific exponent of the power law, and (iii comparison of the power law to alternative model distributions. Consistent with critical state dynamics, avalanche size distributions exhibited robust scaling behavior in which the maximum avalanche size was limited only by the spatial extent of sampling ("finite size" effect. This scale-free dynamics suggests the power law as a model for the distribution of avalanche sizes. Using both the Kolmogorov-Smirnov statistic and a maximum likelihood approach, we found the slope to be close to -1.5, which is in line with previous reports. Finally, the power law model for neuronal avalanches was compared to the exponential and to various heavy-tail distributions based on the Kolmogorov-Smirnov distance and by using a log-likelihood ratio test. Both the power law distribution without and with exponential cut-off provided significantly better fits to the cluster size distributions in neuronal avalanches than the exponential, the lognormal and the gamma distribution. In summary, our findings strongly support the power law scaling in neuronal avalanches, providing further evidence for critical state dynamics in superficial layers of cortex.

  19. Al0.52In0.48P avalanche photodiodes for soft X-ray spectroscopy

    International Nuclear Information System (INIS)

    The performance of Al0.52In0.48P avalanche photodiodes was assessed as soft X-ray detectors at room temperature. The effect of the avalanche gain improved the energy resolution and an energy resolution (FWHM) of 682 eV is reported for 5.9 keV X-rays

  20. Radiation hard avalanche photodiodes for CMS ECAL

    CERN Document Server

    Kuznetsov, A; Britvitch, A; Deiters, K; Egeland, R; Gilbert, B; Godinovic, N; Ingram, Q; Lester, E; Musienko, Y; Puljak, I; Renker, D; Reucroft, S; Rusack, R W; Sakhelashvili, T M; Singovsky, A V; Soric, I; Swain, J D

    2003-01-01

    The photo detectors of the CMS electromagnetic calorimeter have to operate in a rather hostile environment, in a strong magnetic field of 4T and under unprecedented radiation levels. Avalanche Photo Diodes (APDs) have been chosen to detect the scintillation light of the 62,000 lead tungstate crystals in the barrel part of the calorimeter. After a 6 year long R&D work Hamamatsu Photonics produces APDs with a structure that is basically radiation hard. Only a few percent of the delivered APDs are weak due to defects at the surface caused by dust particles in the production process. Since a reliability of 99.9% is required, a method to detect weak APDs before they are built into the detector had to be developed. The described screening method is a combination of **6**0Co irradiations and annealing under bias of all APDs and irradiations with hadrons on a sampling basis.

  1. Zinc Oxide Nanorod Based Ultraviolet Detectors with Wheatstone Bridge Design

    Science.gov (United States)

    Vasudevan, Arun

    This research work, for the first time, investigated metal semiconductor-metal (MSM) zine oxide (ZnO) nanorod based ultra-violet (UV) detectors having a Wheatstone bridge design with a high responsivity at room temperature and above, as well as a responsivity that was largely independent of the change in ambient conditions. The ZnO nanorods which acted as the sensing element of the detector were grown by a chemical growth technique. Studies were conducted to determine the effects on ZnO nanorod properties by varying the concentration of the chemicals used for the rod growth. These studies showed how the rod diameter and the deposition of ZnO nanorods from the solution was controlled by varying the concentration of the chemicals used for the rod growth. Conventional MSM UV detectors were fabricated with ZnO nanorods grown under optimized conditions to determine the dependence of UV response on electrode dimension and rod dimension. These studies gave insights into the dependence of UV response on the width of the electrode, spacing between the electrodes, density of the rod growth, and length and diameter of the rods. The UV responsivity was affected by varying the number of times the seed layer was spin coated, by varying the spin speed of seed layer coating and by varying the annealing temperature of the seed and rod. Based on these studies, optimum conditions for the fabrication of Wheatstone bridge UV ZnO nanorod detectors were determined. The Wheatstone bridge ZnO nanorod UV detectors were fabricated in three different configurations, namely, symmetric, asymmetric, and quasi-symmetric. The transient responses of the symmetric, asymmetric and quasi-symmetric configurations at room temperature and above showed how the response stability differed. At high temperature the responsivity of quasi-symmetric Wheatstone bridge detector configuration did not drop after saturation and the responsivity drifted by 17% to 25% from the room temperature response

  2. The Marocche rock avalanches (Trentino, Italy)

    Science.gov (United States)

    Ivy-Ochs, Susan; Martin, Silvana; Campedel, Paolo; Viganò, Alfio; Alberti, Silvio; Rigo, Manuel; Vockenhuber, Christof

    2015-04-01

    The floors of the Adige and Sarca River valleys are punctuated by numerous rock avalanche deposits of undetermined age. With a view to understanding predisposition and triggering factors, thus ultimately paleoseismicity in the region, we are studying the geomorphology and timing of the largest rock avalanches of the River Sarca-Lake Garda area (e.g., Marocche, Monte Spinale, Lago di Tovel, Lago di Molveno, San Giovanni and Torbole). Among the most extensive of these deposits, with an area of 13 km2 and a volume of about 109 m3, are the Marocche. Marocche deposits cover the lower Sarca valley north of Lake Garda for a length of more than 8 km with 200 m of debris. Both collapse and bedding parallel sliding are a consequence of dip slopes and the extreme relief on the right side of the valley of nearly 2000 m from the bedrock below the valley floor to the peaks combined with the zones of structural weakness. The rock avalanches developed within carbonate rocks of Mesozoic age, mainly limestones of the Jurassic Calcari Grigi Group. The main scarps are located on the western side of the lower Sarca Valley, along the steep faces of Mt. Brento and Mt. Casale. The presence of these scarps is strictly related to the Southern Giudicarie and the Ballino fault systems. The former is here constituted by regular NNE-directed ESE-vergent thrust faults. The latter has been reactivated as normal faults. These complicated structural relationships favored complex failure mechanisms, including rock slide and massive collapse. At the Marocche itself, based on field relationships and analysis of lidar imagery, we differentiated two large rock avalanches: the Marocca di Kas in the south which overlies and in part buries the Marocche (s.s.) in the northern sector. Previous mapping had suggested up to five rock avalanches in the area where we differentiate two. In spite of hypotheses suggesting failure of the rock avalanches onto stagnating late Pleistocene glaciers, preliminary 36Cl

  3. Experimental characterization of semiconductor-based thermal neutron detectors

    Energy Technology Data Exchange (ETDEWEB)

    Bedogni, R., E-mail: roberto.bedogni@lnf.infn.it [IFNF—LNF, via E. Fermi n. 40, 00044 Frascati, Roma (Italy); Bortot, D.; Pola, A.; Introini, M.V.; Lorenzoli, M. [Politecnico di Milano, Dipartimento di Energia, via La Masa 34, 20156 Milano (Italy); INFN—Milano, Via Celoria 16, 20133 Milano (Italy); Gómez-Ros, J.M. [IFNF—LNF, via E. Fermi n. 40, 00044 Frascati, Roma (Italy); CIEMAT, Av. Complutense 40, 28040 Madrid (Spain); Sacco, D. [IFNF—LNF, via E. Fermi n. 40, 00044 Frascati, Roma (Italy); INAIL—DIT, Via di Fontana Candida 1, 00040 Monteporzio Catone (Italy); Esposito, A.; Gentile, A.; Buonomo, B. [IFNF—LNF, via E. Fermi n. 40, 00044 Frascati, Roma (Italy); Palomba, M.; Grossi, A. [ENEA Triga RC-1C.R. Casaccia, via Anguillarese 301, 00060 S. Maria di Galeria, Roma (Italy)

    2015-04-21

    In the framework of NESCOFI@BTF and NEURAPID projects, active thermal neutron detectors were manufactured by depositing appropriate thickness of {sup 6}LiF on commercially available windowless p–i–n diodes. Detectors with different radiator thickness, ranging from 5 to 62 μm, were manufactured by evaporation-based deposition technique and exposed to known values of thermal neutron fluence in two thermal neutron facilities exhibiting different irradiation geometries. The following properties of the detector response were investigated and presented in this work: thickness dependence, impact of parasitic effects (photons and epithermal neutrons), linearity, isotropy, and radiation damage following exposure to large fluence (in the order of 10{sup 12} cm{sup −2})

  4. Microscopic simulation of particle detectors

    International Nuclear Information System (INIS)

    Detailed computer simulations are indispensable tools for the development and optimization of modern particle detectors. The interaction of particles with the sensitive medium, giving rise to ionization or excitation of atoms, is stochastic by its nature. The transport of the resulting photons and charge carriers, which eventually generate the observed signal, is also subject to statistical fluctuations. Together with the readout electronics, these processes - which are ultimately governed by the atomic cross-sections for the respective interactions - pose a fundamental limit to the achievable detector performance. Conventional methods for calculating electron drift lines based on macroscopic transport coefficients used to provide an adequate description for traditional gas-based particle detectors such as wire chambers. However, they are not suitable for small-scale devices such as micropattern gas detectors, which have significantly gained importance in recent years. In this thesis, a novel approach, based on semi-classical (''microscopic'') Monte Carlo simulation, is presented. As a first application, the simulation of avalanche fluctuations is discussed. It is shown that the microscopic electron transport method allows, for the first time, a quantitative prediction of gas gain spectra. Further, it is shown that the shape of avalanche size distributions in uniform fields can be understood intuitively in terms of a toy model extracted from the simulation. Stochastic variations in the number of electrons produced along a charged particle track are another determining factor for the resolution and efficiency of a detector. It is shown that the parameters characterizing primary ionization fluctuations, more specifically the so-called W value and the Fano factor, can be calculated accurately using microscopic techniques such that they need no longer be treated as free variables in the simulation. Profiting from recent progress in the determination of Penning transfer

  5. Hybrid AlGaN-SiC Avalanche Photodiode for Deep-UV Photon Detection

    Science.gov (United States)

    Aslam, Shahid; Herrero, Federico A.; Sigwarth, John; Goldsman, Neil; Akturk, Akin

    2010-01-01

    The proposed device is capable of counting ultraviolet (UV) photons, is compatible for inclusion into space instruments, and has applications as deep- UV detectors for calibration systems, curing systems, and crack detection. The device is based on a Separate Absorption and Charge Multiplication (SACM) structure. It is based on aluminum gallium nitride (AlGaN) absorber on a silicon carbide APD (avalanche photodiode). The AlGaN layer absorbs incident UV photons and injects photogenerated carriers into an underlying SiC APD that is operated in Geiger mode and provides current multiplication via avalanche breakdown. The solid-state detector is capable of sensing 100-to-365-nanometer wavelength radiation at a flux level as low as 6 photons/pixel/s. Advantages include, visible-light blindness, operation in harsh environments (e.g., high temperatures), deep-UV detection response, high gain, and Geiger mode operation at low voltage. Furthermore, the device can also be designed in array formats, e.g., linear arrays or 2D arrays (micropixels inside a superpixel).

  6. Skyrmion based microwave detectors and harvesting

    Energy Technology Data Exchange (ETDEWEB)

    Finocchio, G.; Giordano, A. [Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, Viale F. Stagno d' Alcontres 31, 98166 Messina (Italy); Ricci, M.; Burrascano, P. [Department of Engineering, Polo Scientifico Didattico di Terni, University of Perugia, Terni, TR I-50100 (Italy); Tomasello, R.; Lanuzza, M. [Department of Computer Science, Modelling, Electronics and System Science, University of Calabria, via P. Bucci 41C, I-87036 Rende (CS) (Italy); Puliafito, V.; Azzerboni, B. [Department of Engineering, University of Messina, c.da di Dio, I-98166 Messina (Italy); Carpentieri, M. [Department of Electrical and Information Engineering, Politecnico di Bari, via E. Orabona 4, I-70125 Bari (Italy)

    2015-12-28

    Magnetic skyrmions are topologically protected states that are very promising for the design of the next generation of ultra-low-power electronic devices. In this letter, we propose a magnetic tunnel junction based spin-transfer torque diode with a magnetic skyrmion as ground state and a perpendicular polarizer patterned as nano-contact for a local injection of the current. The key result is the possibility to achieve sensitivities (i.e., detection voltage over input microwave power) larger than 2000 V/W for optimized contact diameters. We also pointed out that large enough voltage controlled magnetocrystalline anisotropy could significantly improve the sensitivity. Our results can be very useful for the identification of a class of spin-torque diodes with a non-uniform ground state and to understand the fundamental physics of the skyrmion dynamical properties.

  7. Skyrmion based microwave detectors and harvesting

    International Nuclear Information System (INIS)

    Magnetic skyrmions are topologically protected states that are very promising for the design of the next generation of ultra-low-power electronic devices. In this letter, we propose a magnetic tunnel junction based spin-transfer torque diode with a magnetic skyrmion as ground state and a perpendicular polarizer patterned as nano-contact for a local injection of the current. The key result is the possibility to achieve sensitivities (i.e., detection voltage over input microwave power) larger than 2000 V/W for optimized contact diameters. We also pointed out that large enough voltage controlled magnetocrystalline anisotropy could significantly improve the sensitivity. Our results can be very useful for the identification of a class of spin-torque diodes with a non-uniform ground state and to understand the fundamental physics of the skyrmion dynamical properties

  8. An X-ray scanner prototype based on a novel hybrid gaseous detector

    CERN Document Server

    Iacobaeus, C; Lund-Jensen, B; Peskov, Vladimir

    2007-01-01

    We have developed a prototype of a new type of hybrid X-ray detector. It contains a thin wall (few μm) edge- illuminated lead glass capillary plate (acting as a converter of X-rays photons to primary electrons) combined with a microgap parallel-plate avalanche chamber operating in various gas mixtures at 1 atm. The operation of these converters was studied in a wide range of X-ray energies (from 6 to 60 keV) at incident angles varying from 0° to 90°. The detection efficiency, depending on the geometry, photon's energy, incident angle and the mode of operation, was between a few and 40%. The position resolution achieved was 50 μm in digital form and was practically independent of the photon's energy or gas mixture. The developed detector may open new possibilities for medical imaging, for example in mammography, portal imaging, radiography (including security devices), crystallography and many other applications.

  9. Spatio-temporal avalanche forecasting with Support Vector Machines

    Directory of Open Access Journals (Sweden)

    A. Pozdnoukhov

    2011-02-01

    Full Text Available This paper explores the use of the Support Vector Machine (SVM as a data exploration tool and a predictive engine for spatio-temporal forecasting of snow avalanches. Based on the historical observations of avalanche activity, meteorological conditions and snowpack observations in the field, an SVM is used to build a data-driven spatio-temporal forecast for the local mountain region. It incorporates the outputs of simple physics-based and statistical approaches used to interpolate meteorological and snowpack-related data over a digital elevation model of the region. The interpretation of the produced forecast is discussed, and the quality of the model is validated using observations and avalanche bulletins of the recent years. The insight into the model behaviour is presented to highlight the interpretability of the model, its abilities to produce reliable forecasts for individual avalanche paths and sensitivity to input data. Estimates of prediction uncertainty are obtained with ensemble forecasting. The case study was carried out using data from the avalanche forecasting service in the Locaber region of Scotland, where avalanches are forecast on a daily basis during the winter months.

  10. Effect of junction temperature on the large-signal properties of a 94 GHz silicon based double-drift region impact avalanche transit time device

    Institute of Scientific and Technical Information of China (English)

    Aritra Acharyya; Suranjana Banerjee; J.P.Banerjee

    2013-01-01

    The authors have developed a large-signal simulation technique extending an in-house small-signal simulation code for analyzing a 94 GHz double-drift region impact avalanche transit time device based on silicon with a non-sinusoidal voltage excitation and studied the effect of junction temperature between 300 and 550 K on the large-signal characteristics of the device for both continuous wave (CW) and pulsed modes of operation.Results show that the large-signal RF power output of the device in both CW and pulsed modes increases with the increase of voltage modulation factor up to 60%,but decreases sharply with further increase of voltage modulation factor for a particular junction temperature; while the same parameter increases with the increase of junction temperature for a particular voltage modulation factor.Heat sinks made of copper and type-ⅡA diamond are designed to carry out the steady-state and transient thermal analysis of the device operating in CW and pulsed modes respectively.Authors have adopted Olson's method to carry out the transient analysis of the device,which clearly establishes the superiority of type-ⅡA diamond over copper as the heat sink material of the device from the standpoint of the undesirable effect of frequency chirping due to thermal transients in the pulsed mode.

  11. Application of PN and avalanche silicon photodiodes to low-level optical

    Science.gov (United States)

    Eppeldauer, G.; Schaefer, A. R.

    1988-01-01

    New approaches to the discovery of other planetary systems require very sensitive and stable detection techniques in order to succeed. Two methods in particular, the astrometric and the photometric methods, require this. To begin understanding the problems and limitations of solid state detectors regarding this application, preliminary experiments were performed at the National Bureau of Standards and a low light level detector characterization facility was built. This facility is briefly described, and the results of tests conducted in it are outlined. A breadboard photometer that was used to obtain stellar brightness ratio precision data is described. The design principles of PN and avalanche silicon photodiodes based on low light level measuring circuits are discussed.

  12. Neuronal avalanches and coherence potentials

    Science.gov (United States)

    Plenz, D.

    2012-05-01

    The mammalian cortex consists of a vast network of weakly interacting excitable cells called neurons. Neurons must synchronize their activities in order to trigger activity in neighboring neurons. Moreover, interactions must be carefully regulated to remain weak (but not too weak) such that cascades of active neuronal groups avoid explosive growth yet allow for activity propagation over long-distances. Such a balance is robustly realized for neuronal avalanches, which are defined as cortical activity cascades that follow precise power laws. In experiments, scale-invariant neuronal avalanche dynamics have been observed during spontaneous cortical activity in isolated preparations in vitro as well as in the ongoing cortical activity of awake animals and in humans. Theory, models, and experiments suggest that neuronal avalanches are the signature of brain function near criticality at which the cortex optimally responds to inputs and maximizes its information capacity. Importantly, avalanche dynamics allow for the emergence of a subset of avalanches, the coherence potentials. They emerge when the synchronization of a local neuronal group exceeds a local threshold, at which the system spawns replicas of the local group activity at distant network sites. The functional importance of coherence potentials will be discussed in the context of propagating structures, such as gliders in balanced cellular automata. Gliders constitute local population dynamics that replicate in space after a finite number of generations and are thought to provide cellular automata with universal computation. Avalanches and coherence potentials are proposed to constitute a modern framework of cortical synchronization dynamics that underlies brain function.

  13. A revision of the Haiming rock avalanche (Eastern Alps)

    Science.gov (United States)

    Dufresne, Anja; Ostermann, Marc; Kelfoun, Karim; Ring, Max; Asam, Dario; Prager, Christoph

    2016-04-01

    The carbonate Haiming rock avalanche is directly neighbouring the larger Tschirgant rock avalanche deposit, both located in the upper Inn valley (Tyrol, Austria). Based on detailed morpho-lithologic mapping of the deposit, which has not been done at Haiming before, the sedimentology of the Holocene landslide debris is characterised. Structural-tectonic elements of the bedrock units at the scarp area are supplemented with borehole data from drillings at the source area giving valuable insights into the complex geological bedrock composition and structure. New source and runout reconstructions allow updated volumetric calculations, which are subsequently integrated into numerical runout modelling. Haiming is one of few topographically unobstructed rock avalanches, yet its morphology was greatly influenced by fluvial terraces, which are still discernible through the deposit on LiDAR hillshade images. We also address the influence of the rock avalanche on the valley floor and local river system as a short-lived dam and its interaction with fluvial incision. Finally, we discuss the Haiming rock avalanche in view of the other massive rock slope failures in the area ("Fernpass cluster"), their spatio-temporal distribution, and point out further highlights of this simple(?) rock avalanche deposit.

  14. Neutron detector based on lithiated sol-gel glass

    CERN Document Server

    Wallace, S; Miller, L F; Dai, S

    2002-01-01

    A neutron detector technology is demonstrated based on sup 6 Li/ sup 1 sup 0 B doped sol-gel glass. The detector is a sol-gel glass film coated silicon surface barrier detector (SBD). The ionized charged particles from (n, alpha) reactions in the sol-gel film enter the SBD and are counted. Data showing that gamma-ray pulse amplitudes interfere with identifying charged particles that exit the film layer with energies below the gamma-ray energy is presented. Experiments were performed showing the effect of sup 1 sup 3 sup 7 Cs and sup 6 sup 0 Co gamma rays on the SBD detector. The reaction product energies of the triton and alpha particles from sup 6 Li are significantly greater than the energies of the Compton electrons from high-energy gamma rays, allowing the measurement of neutrons in a high gamma background. The sol-gel radiation detection technology may be applicable to the characterization of transuranic waste, spent nuclear fuel and to the monitoring of stored plutonium.

  15. Characterization and Monte Carlo simulation of single ion Geiger mode avalanche diodes integrated with a quantum dot nanostructure

    Science.gov (United States)

    Sharma, Peter; Abraham, J. B. S.; Ten Eyck, G.; Childs, K. D.; Bielejec, E.; Carroll, M. S.

    Detection of single ion implantation within a nanostructure is necessary for the high yield fabrication of implanted donor-based quantum computing architectures. Single ion Geiger mode avalanche (SIGMA) diodes with a laterally integrated nanostructure capable of forming a quantum dot were fabricated and characterized using photon pulses. The detection efficiency of this design was measured as a function of wavelength, lateral position, and for varying delay times between the photon pulse and the overbias detection window. Monte Carlo simulations based only on the random diffusion of photo-generated carriers and the geometrical placement of the avalanche region agrees qualitatively with device characterization. Based on these results, SIGMA detection efficiency appears to be determined solely by the diffusion of photo-generated electron-hole pairs into a buried avalanche region. Device performance is then highly dependent on the uniformity of the underlying silicon substrate and the proximity of photo-generated carriers to the silicon-silicon dioxide interface, which are the most important limiting factors for reaching the single ion detection limit with SIGMA detectors. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  16. Distribution-based CFAR detectors in SAR images

    Institute of Scientific and Technical Information of China (English)

    Gan Rongbing; Wang Jianguo

    2006-01-01

    As traditional two-parameter constant false alarm rate (CFAR) target detection algorithms in SAR images ignore target distribution, their performances are not the best or near best. As the resolution of SAR images increases, small targets present more pixels in SAR images. So the target distribution is of much significance. Distribution-based CFAR detection algorithm is presented. We unite the pixels around the test cell, and estimate the distribution of test cell by them. Generalized Likelihood Ratio Test (GLRT) is used to deduce the detectors. The performance of the distribution-based CFAR (DBCFAR) detectors is analyzed theoretically. False alarms of DBCFAR detection are fewer than those of CFAR at the same detection rate. Finally experiments are done and the results show the performance of DBCFAR is out of conventional CFAR. False alarms of DBCFAR detection are concentrated while those of CFAR detection are dispersive.

  17. Accelerometer-Based Event Detector for Low-Power Applications

    OpenAIRE

    József Smidla; Gyula Simon

    2013-01-01

    In this paper, an adaptive, autocovariance-based event detection algorithm is proposed, which can be used with micro-electro-mechanical systems (MEMS) accelerometer sensors to build inexpensive and power efficient event detectors. The algorithm works well with low signal-to-noise ratio input signals, and its computational complexity is very low, allowing its utilization on inexpensive low-end embedded sensor devices. The proposed algorithm decreases its energy consumption by lowering its duty...

  18. Signal and Noise Properties of Position-Sensitive Avalanche Photodiodes

    OpenAIRE

    Yang, Yongfeng; Wu, Yibao; Farrell, Richard; Dokhale, Purushottam A.; Shah, Kanai S.; Cherry, Simon R.

    2011-01-01

    After many years of development, position-sensitive avalanche photodiodes (PSAPDs) are now being incorporated into a range of scintillation detector systems, including those used in high-resolution small-animal PET and PET/MR scanners. In this work, the signal, noise, signal-to-noise ratio (SNR), flood histogram and timing resolution were measured for lutetium oxyorthosilicate (LSO) scintillator arrays coupled to PSAPDs ranging in size from 10–20 mm, and the optimum bias voltage and working t...

  19. Performances of a HGCDTE APD Based Detector with Electric Cooling for 2-μm DIAL/IPDA Applications

    Science.gov (United States)

    Dumas, A.; Rothman, J.; Gibert, F.; Lasfargues, G.; Zanatta, J.-P.; Edouart, D.

    2016-06-01

    In this work we report on design and testing of an HgCdTe Avalanche Photodiode (APD) detector assembly for lidar applications in the Short Wavelength Infrared Region (SWIR : 1,5 - 2 μm). This detector consists in a set of diodes set in parallel -making a 200 μm large sensitive area- and connected to a custom high gain TransImpedance Amplifier (TIA). A commercial four stages Peltier cooler is used to reach an operating temperature of 185K. Crucial performances for lidar use are investigated : linearity, dynamic range, spatial homogeneity, noise and resistance to intense illumination.

  20. Avalanche effects near nanojunctions

    Science.gov (United States)

    Nandigana, Vishal V. R.; Aluru, N. R.

    2016-07-01

    In this article, we perform a computational investigation of a nanopore connected to external fluidic reservoirs of asymmetric geometries. The asymmetry between the reservoirs is achieved by changing the cross-sectional areas, and the reservoirs are designated as the micropore reservoir and macropore reservoir. When an electric field is applied, which is directed from the macropore towards the micropore reservoir, we observe local nonequilibrium chaotic current oscillations. The current oscillations originate at the micropore-nanopore interface owing to the local cascade of ions; we refer to this phenomenon as the "avalanche effects." We mathematically quantify chaos in terms of the maximum Lyapunov exponent. The maximum Lyapunov exponent exhibits a monotonic increase with the applied voltage and the macropore reservoir diameter. The temporal power spectra maps of the chaotic currents depict a low-frequency "1 /f "-type dynamics for the voltage chaos and "1 /f2 "-type dynamics for the macropore reservoir chaos. The results presented here offer avenues to manipulate ionic diodes and fluidic pumps.

  1. Room temperature photon number resolving detector at telecom wavelengths

    OpenAIRE

    Pomarico, Enrico; Sanguinetti, Bruno; Thew, Robert Thomas; Zbinden, Hugo

    2010-01-01

    In this paper we present a photon number resolving detector at infrared wavelengths, operating at room temperature and with a large dynamic range. It is based on the up-conversion of a signal at 1559 nm into visible wavelength and on its detection by a thermoelectrically cooled multi-pixel silicon avalanche photodiodode, also known as a Silicon Photon Multiplier. With the appropriate up-conversion this scheme can be implemented for arbitrary wavelengths above the visible spectral window. The ...

  2. SENTIRAD-An innovative personal radiation detector based on a scintillation detector and a silicon photomultiplier

    International Nuclear Information System (INIS)

    The alarming personal radiation detector (PRD) is a device intended for Homeland Security (HLS) applications. This portable device is designed to be worn or carried by security personnel to detect photon-emitting radioactive materials for the purpose of crime prevention. PRD is required to meet the scope of specifications defined by various HLS standards for radiation detection. It is mandatory that the device be sensitive and simultaneously small, pocket-sized, of robust mechanical design and carriable on the user's body. To serve these specialized purposes and requirements, we developed the SENTIRAD, a new radiation detector designed to meet the performance criteria established for counterterrorist applications. SENTIRAD is the first commercially available PRD based on a CsI(Tl) scintillation crystal that is optically coupled with a silicon photomultiplier (SiPM) serving as a light sensor. The rapidly developing technology of SiPM, a multipixel semiconductor photodiode that operates in Geiger mode, has been thoroughly investigated in previous studies. This paper presents the design considerations, constraints and radiological performance relating to the SENTIRAD radiation sensor.

  3. SENTIRAD—An innovative personal radiation detector based on a scintillation detector and a silicon photomultiplier

    Science.gov (United States)

    Osovizky, A.; Ginzburg, D.; Manor, A.; Seif, R.; Ghelman, M.; Cohen-Zada, I.; Ellenbogen, M.; Bronfenmakher, V.; Pushkarsky, V.; Gonen, E.; Mazor, T.; Cohen, Y.

    2011-10-01

    The alarming personal radiation detector (PRD) is a device intended for Homeland Security (HLS) applications. This portable device is designed to be worn or carried by security personnel to detect photon-emitting radioactive materials for the purpose of crime prevention. PRD is required to meet the scope of specifications defined by various HLS standards for radiation detection. It is mandatory that the device be sensitive and simultaneously small, pocket-sized, of robust mechanical design and carriable on the user's body. To serve these specialized purposes and requirements, we developed the SENTIRAD, a new radiation detector designed to meet the performance criteria established for counterterrorist applications. SENTIRAD is the first commercially available PRD based on a CsI(Tl) scintillation crystal that is optically coupled with a silicon photomultiplier (SiPM) serving as a light sensor. The rapidly developing technology of SiPM, a multipixel semiconductor photodiode that operates in Geiger mode, has been thoroughly investigated in previous studies. This paper presents the design considerations, constraints and radiological performance relating to the SENTIRAD radiation sensor.

  4. A fully-integrated 12.5-Gb/s 850-nm CMOS optical receiver based on a spatially-modulated avalanche photodetector

    NARCIS (Netherlands)

    Lee, M.J.; Youn, J.S.; Park, K.Y.; Choi, W.Y.

    2014-01-01

    We present a fully integrated 12.5-Gb/s optical receiver fabricated with standard 0.13-µm complementary metal-oxide-semiconductor (CMOS) technology for 850-nm optical interconnect applications. Our integrated optical receiver includes a newly proposed CMOS-compatible spatially-modulated avalanche ph

  5. Note: All solid-state high repetitive sub-nanosecond risetime pulse generator based on bulk gallium arsenide avalanche semiconductor switches

    Science.gov (United States)

    Hu, Long; Su, Jiancang; Ding, Zhenjie; Hao, Qingsong; Fan, Yajun; Liu, Chunliang

    2016-08-01

    An all solid-state high repetitive sub-nanosecond risetime pulse generator featuring low-energy-triggered bulk gallium arsenide (GaAs) avalanche semiconductor switches and a step-type transmission line is presented. The step-type transmission line with two stages is charged to a potential of 5.0 kV also biasing at the switches. The bulk GaAs avalanche semiconductor switch closes within sub-nanosecond range when illuminated with approximately 87 nJ of laser energy at 905 nm in a single pulse. An asymmetric dipolar pulse with peak-to-peak amplitude of 9.6 kV and risetime of 0.65 ns is produced on a resistive load of 50 Ω. A technique that allows for repetition-rate multiplication of pulse trains experimentally demonstrated that the parallel-connected bulk GaAs avalanche semiconductor switches are triggered in sequence. The highest repetition rate is decided by recovery time of the bulk GaAs avalanche semiconductor switch, and the operating result of 100 kHz of the generator is discussed.

  6. Heterodyne detection with mismatch correction base on array detector

    Science.gov (United States)

    Hongzhou, Dong; Guoqiang, Li; Ruofu, Yang; Chunping, Yang; Mingwu, Ao

    2016-07-01

    Based on an array detector, a new heterodyne detection system, which can correct the mismatches of amplitude and phase between signal and local oscillation (LO) beams, is presented in this paper. In the light of the fact that, for a heterodyne signal, there is a certain phase difference between the adjacent two samples of analog-to-digital converter (ADC), we propose to correct the spatial phase mismatch by use of the time-domain phase difference. The corrections can be realized by shifting the output sequences acquired from the detector elements in the array, and the steps of the shifting depend on the quantity of spatial phase mismatch. Numerical calculations of heterodyne efficiency are conducted to confirm the excellent performance of our system. Being different from previous works, our system needs not extra optical devices, so it provides probably an effective means to ease the problem resulted from the mismatches.

  7. Heterodyne detection with mismatch correction based on array detector

    Science.gov (United States)

    Dong, Hongzhou; Li, Guoqiang; Yang, Ruofu; Yang, Chunping; Ao, Mingwu

    2016-07-01

    Based on an array detector, a new heterodyne detection system, which can correct the mismatches of amplitude and phase between signal and local oscillation (LO) beams, is presented in this paper. In the light of the fact that, for a heterodyne signal, there is a certain phase difference between the adjacent two samples of analog-to-digital converter (ADC), we propose to correct the spatial phase mismatch by use of the time-domain phase difference. The corrections can be realized by shifting the output sequences acquired from the detector elements in the array, and the steps of the shifting depend on the quantity of spatial phase mismatch. Numerical calculations of heterodyne efficiency are conducted to confirm the excellent performance of our system. Being different from previous works, our system needs not extra optical devices, so it provides probably an effective means to ease the problem resulted from the mismatches.

  8. Intrinsic Radiation in Lutetium Based PET Detector: Advantages and Disadvantages

    CERN Document Server

    Wei, Qingyang

    2015-01-01

    Lutetium (Lu) based scintillators such as LSO and LYSO, are widely used in modern PET detectors due to their high stopping power for 511 keV gamma rays, high light yield and short decay time. However, 2.6% of naturally occurring Lu is 176Lu, a long-lived radioactive element including a beta decay and three major simultaneous gamma decays. This phenomenon introduces random events to PET systems that affects the system performance. On the other hand, the advantages of intrinsic radiation of 176Lu (IRL) continues to be exploited. In this paper, research literatures about IRL in PET detectors are reviewed. Details about the adverse effects of IRL to PET and their solutions, as well as the useful applications are presented and discussed.

  9. Prototype of a large neutron detector based on MWPC

    Institute of Scientific and Technical Information of China (English)

    TIAN LiChao; QI HuiRong; SUN ZhiJia; WANG YanFeng; ZHANG Jian; LIU RongGuang; ZHAO YuBin

    2014-01-01

    A prototype of large-area position sensitive neutron detector was designed and constructed according to the requirements of the Small-Angle Scattering spectrometer of China Spallation Neutron Source (CSNS).The detector was based on the 3He neutron convertor and MWPC with an effective area of 650 mm×650 mm.A prototype was completed and tested with 55Fe X-ray.The high-pressure vessel was designed and constructed with high-strength aluminum alloy.A position resolution of about 4.6 mm×2.3 mm (FWHM) and efficiency > 65% for neutrons with wavelength of 1.8(A) was determined after the operational gas filled.

  10. Angular resolution of space-based gravitational wave detectors

    International Nuclear Information System (INIS)

    Proposed space-based gravitational wave antennas involve satellites arrayed either in an equilateral triangle around the Earth in the ecliptic plane (the ecliptic-plane option) or in an equilateral triangle orbiting the Sun in such a way that the plane of the triangle is tilted at 60 deg, relative to the ecliptic (the precessing-plane option). In this paper, we explore the angular resolution of these two classes of detectors for two kinds of sources (essentially monochromatic compact binaries and coalescing massive-black-hole binaries) using time-domain expressions for the gravitational waveform that are accurate to 4/2 PN order. Our results display an interesting effect not previously reported in the literature, and particularly underline the importance of including the higher-order PN terms in the waveform when predicting the angular resolution of ecliptic-plane detector arrays

  11. 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.

  12. The remote monitoring system of BESⅢ detector based on web

    International Nuclear Information System (INIS)

    It designed a remote monitoring system of BESⅢ experiment based on web. The software of the system is mainly based on module programming. The Ajax technology and the MVC pattern is used in system framework construction. The function of selecting multiple tables is realized by structural checkbox tree using jstree library. Data chart is plotted by High Charts library. The updating of data curve is realized by the method of calculating the time span between the real data record to measure the http request. The system design can be used by detector monitoring system like BESⅢ. (authors)

  13. Gamma-ray imaging detectors based on silicon drift detectors arrays coupled to a single scintillator

    International Nuclear Information System (INIS)

    Arrays of Silicon Drift Detectors (SDDs) coupled to a single scintillator, according to the Anger Camera scheme, can be successfully employed in gamma-ray imaging. The low value of output capacitance of a SDD allows to reach a lower electronics noise with respect to conventional silicon photodiodes used in scintillation detection. A small prototype of gamma camera with sub-millimeter resolution has been realized by using a monolithic array of small SDDs (5 mm2 each unit) with on-chip JFET. For the realization of gamma cameras of larger areas based on single units assembled in array, SDDs of 30 mm2 of area with external JFET have been also experimented

  14. Snow Avalanche Disturbance Ecology: Examples From the San Juan Mountains, Colorado.

    Science.gov (United States)

    Simonson, S.; Fassnacht, S. R.

    2008-12-01

    We evaluated landscape ecology approaches to characterize snow avalanche paths based on patterns of plant species composition and evidence of disturbance. Historical records of avalanche incidents, patterns in the annual growth layers of woody plants, and distributions of plant species can be used to quantify and map the frequency and magnitude of snow slide events. Near Silverton, Colorado, a series of snow storms in January of 2005 resulted in many avalanche paths running full track at 30 and 100 year return frequency. Many avalanches cut fresh trimlines, widening their tracks by uprooting, stripping, and breaking mature trees. Powerful avalanches deposited massive piles of snow, rocks, and woody debris in their runout zones. We used cross-section discs and cores of representative downed trees to detect dendro-ecological signals of past snow avalanche disturbance. Avalanche signals included impact scars from the moving snow and associated wind blast, relative width of annual growth rings, and development of reaction wood in response to tilting. Initial measurements of plant diversity and disturbance along the elevation gradient of an avalanche path near Silverton indicate that avalanche activity influences patterns of forest cover, contributes to the high local plant species diversity, and provides opportunities for new seedling establishment.

  15. Large area radiation detectors based on II VI thin films

    Science.gov (United States)

    Quevedo-Lopez, Manuel

    2015-03-01

    The development of low temperature device technologies that have enabled flexible displays also present opportunities for flexible electronics and flexible integrated systems. Of particular interest are possible applications in flexible, low metal content, sensor systems for unattended ground sensors, smart medical bandages, electronic ID tags for geo-location, conformal antennas, neutron/gamma-ray/x-ray detectors, etc. In this talk, our efforts to develop novel CMOS integration schemes, circuits, memory, sensors as well as novel contacts, dielectrics and semiconductors for flexible electronics are presented. In particular, in this presentation we discuss fundamental materials properties including crystalline structure, interfacial reactions, doping, etc. defining performance and reliability of II-VI-based radiation sensors. We investigate the optimal thickness of a semiconductor diode for thin-film solid state thermal neutron detectors. Besides II-VI materials, we also evaluated several diode materials, Si, CdTe,GaAs, C (diamond), and ZnO, and two neutron converter materials,10B and 6LiF. We determine the minimum semiconductor thickness needed to achieve maximum neutron detection efficiency. By keeping the semiconductor thickness to a minimum, gamma rejection is kept as high as possible. In this way, we optimize detector performance for different thin-film semiconductor materials.

  16. Switching variability index based multiple strategy CFAR detector

    Institute of Scientific and Technical Information of China (English)

    Yang Li; Zhenyuan Ji; Bingfei Li; Gil Alterovitz

    2014-01-01

    A switching variability index (SVI) constant false alarm rate (CFAR) detector is proposed for improving the detection performance of VI-CFAR detectors in multiple targets back-grounds. When the presence of non-homogeneity in CFAR re-ference windows is indicated by a VI-CFAR detector, a switching-CFAR detector is introduced to optimize the performance of the VI-CFAR detector in homogeneous, multiple targets and clut-ter edge backgrounds. The structure and parameters selection method of the SVI-CFAR detector is presented. Comparisons with classic CFAR detectors and recently proposed detectors are also given. Theoretical analysis and simulation results show that SVI-CFAR detector maintains the good performance of the VI-CFAR detector in homogeneous and clutter edge backgrounds, while greatly improving the capacity of anti-multi targets.

  17. The MAPS based PXL vertex detector for the STAR experiment

    Science.gov (United States)

    Contin, G.; Anderssen, E.; Greiner, L.; Schambach, J.; Silber, J.; Stezelberger, T.; Sun, X.; Szelezniak, M.; Vu, C.; Wieman, H.; Woodmansee, S.

    2015-03-01

    The Heavy Flavor Tracker (HFT) was installed in the STAR experiment for the 2014 heavy ion run of RHIC. Designed to improve the vertex resolution and extend the measurement capabilities in the heavy flavor domain, the HFT is composed of three different silicon detectors based on CMOS monolithic active pixels (MAPS), pads and strips respectively, arranged in four concentric cylinders close to the STAR interaction point. The two innermost HFT layers are placed at a radius of 2.7 and 8 cm from the beam line, respectively, and accommodate 400 ultra-thin (50 μ m) high resolution MAPS sensors arranged in 10-sensor ladders to cover a total silicon area of 0.16 m2. Each sensor includes a pixel array of 928 rows and 960 columns with a 20.7 μ m pixel pitch, providing a sensitive area of ~ 3.8 cm2. The architecture is based on a column parallel readout with amplification and correlated double sampling inside each pixel. Each column is terminated with a high precision discriminator, is read out in a rolling shutter mode and the output is processed through an integrated zero suppression logic. The results are stored in two SRAM with ping-pong arrangement for a continuous readout. The sensor features 185.6 μ s readout time and 170 mW/cm2 power dissipation. The detector is air-cooled, allowing a global material budget as low as 0.39% on the inner layer. A novel mechanical approach to detector insertion enables effective installation and integration of the pixel layers within an 8 hour shift during the on-going STAR run.In addition to a detailed description of the detector characteristics, the experience of the first months of data taking will be presented in this paper, with a particular focus on sensor threshold calibration, latch-up protection procedures and general system operations aimed at stabilizing the running conditions. Issues faced during the 2014 run will be discussed together with the implemented solutions. A preliminary analysis of the detector performance

  18. The MAPS based PXL vertex detector for the STAR experiment

    International Nuclear Information System (INIS)

    The Heavy Flavor Tracker (HFT) was installed in the STAR experiment for the 2014 heavy ion run of RHIC. Designed to improve the vertex resolution and extend the measurement capabilities in the heavy flavor domain, the HFT is composed of three different silicon detectors based on CMOS monolithic active pixels (MAPS), pads and strips respectively, arranged in four concentric cylinders close to the STAR interaction point. The two innermost HFT layers are placed at a radius of 2.7 and 8 cm from the beam line, respectively, and accommodate 400 ultra-thin (50 μ m) high resolution MAPS sensors arranged in 10-sensor ladders to cover a total silicon area of 0.16 m2. Each sensor includes a pixel array of 928 rows and 960 columns with a 20.7 μ m pixel pitch, providing a sensitive area of ∼ 3.8 cm2. The architecture is based on a column parallel readout with amplification and correlated double sampling inside each pixel. Each column is terminated with a high precision discriminator, is read out in a rolling shutter mode and the output is processed through an integrated zero suppression logic. The results are stored in two SRAM with ping-pong arrangement for a continuous readout. The sensor features 185.6 μ s readout time and 170 mW/cm2 power dissipation. The detector is air-cooled, allowing a global material budget as low as 0.39% on the inner layer. A novel mechanical approach to detector insertion enables effective installation and integration of the pixel layers within an 8 hour shift during the on-going STAR run.In addition to a detailed description of the detector characteristics, the experience of the first months of data taking will be presented in this paper, with a particular focus on sensor threshold calibration, latch-up protection procedures and general system operations aimed at stabilizing the running conditions. Issues faced during the 2014 run will be discussed together with the implemented solutions. A preliminary analysis of the detector

  19. Intrinsic Radiation in Lutetium Based PET Detector: Advantages and Disadvantages

    OpenAIRE

    Wei, Qingyang

    2015-01-01

    Lutetium (Lu) based scintillators such as LSO and LYSO, are widely used in modern PET detectors due to their high stopping power for 511 keV gamma rays, high light yield and short decay time. However, 2.6% of naturally occurring Lu is 176Lu, a long-lived radioactive element including a beta decay and three major simultaneous gamma decays. This phenomenon introduces random events to PET systems that affects the system performance. On the other hand, the advantages of intrinsic radiation of 176...

  20. The STACEE Ground-Based Gamma-Ray Detector

    CERN Document Server

    Gingrich, D M; Bramel, D; Carson, J; Covault, C E; Fortin, P; Hanna, D S; Hinton, J A; Jarvis, A; Kildea, J; Lindner, T; Müller, C; Mukherjee, R; Ong, R A; Ragan, K; Scalzo, R A; Theoret, C G; Williams, D A; Zweerink, J A

    2005-01-01

    We describe the design and performance of the Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) in its complete configuration. STACEE uses the heliostats of a solar energy research facility to collect and focus the Cherenkov photons produced in gamma-ray induced air showers. The light is concentrated onto an array of photomultiplier tubes located near the top of a tower. The large Cherenkov photon collection area of STACEE results in a gamma-ray energy threshold below that of previous ground-based detectors. STACEE is being used to observe pulsars, supernova remnants, active galactic nuclei, and gamma-ray bursts.

  1. Arrest of Avalanche Propagation by Discontinuities on Snow Cover

    Science.gov (United States)

    Frigo, B.; Chiaia, B.

    2009-04-01

    Considering the spatial variability of the snow cover, the paper analyses, in the framework of Fracture Mechanics, the Mode II fracture propagation on snow cover that leads to large dry slab avalanches. Under the hypothesis of a perfectly brittle phenomenon, avalanche triggering is usually investigated numerically by means of Linear Elastic Fracture Mechanics (McClung, 1979; Chiaia et al., 2008). Since, however, the real phenomenon is intrinsically dynamical, another aspect to investigate is represented by dynamic fracture propagation. In this paper, we model dynamic crack propagation into a dry snow slab, to assess the possibility of crack arrest due to the presence of weak zones distributed along the snow slope. As a consequence of the first triggering mechanism (the Mode II fracture propagation on the weak plane), the secondary Mode I crack propagation in the crown is studied by means of numerical simulations based on Dynamic Elastic Fracture Mechanics and on the theory of crack arresters. By taking into account kinetic energy and using the FEM software FRANC 2D (Wawrzynek and Ingraffea, 1993), several paths of crown fracture propagation and their stability have been investigated. The snowpack is considered as a linear-elastic plate (2D problem), whose physical and mechanical parameters are chosen according to classical literature values. To investigate the possible arrest of crown fracture, we apply the theory of crack arresters, usually adopted for pipelines and perforated steel sheets fracture problems. To study crack arrest, different crack paths are simulated, in discontinuous (equipped with different shapes and geometries of artificial voids) snowpacks. The simulations show the effectiveness of these weak zones, to reduce substantially the crack driving force of the propagating fracture. This means that, increasing spatial variability tends to stabilize the snow slope, eventually splitting a major avalanche event into smaller, independent avalanches. Our

  2. Gaseous wire detectors

    International Nuclear Information System (INIS)

    This article represents a series of three lectures describing topics needed to understand the design of typical gaseous wire detectors used in large high energy physics experiments; including the electrostatic design, drift of electrons in the electric and magnetic field, the avalanche, signal creation, limits on the position accuracy as well as some problems one encounters in practical operations

  3. A Simple Numerical Approach To Avalanche Forecasting: Chowkibal-tangdhar Axis, Kashmir, India

    Science.gov (United States)

    Singh, Amreek; Joshi, J. C.; Ganju, Ashwagosha

    Chowkibal-Tangdhar axis of Kashmir region in India is a stretch of about 36 kms with 26 major avalanche sites. It falls in Pir Panjal range and crosses Nastachun pass cutting across Shamsabari Mountains, at an altitude of 3120m. Snow-meteorological data of 10 years recorded at two different altitude zones in the axis were statistically analyzed in the backdrop of the avalanche occurrences observed during the same period on the axis. The results show primary significance towards avalanching for certain variables e.g. fresh snow depth, snowfall rate, standing snow, water equivalent of fresh precipitation, recorded at either observatory. But for others, especially wind parameters, trend of significance is different for the two observatories. The results have also been compared with one similar study conducted for the data from Kooteny pass, British Columbia, Canada. The comparison shows a similar significance trend for most of the variables for the two areas. The attempt has also been made to identify the ranges of variables responsible for the formation of loose snow, slab, dry or wet avalanches with their avalanche size. The overall study provides an objective criterion to assess the significance of individual snow-met variables from avalanching point of view. The significance criterion thus evolved has been further implemented in the development of a simple numerical model to assess the probability, type and size of avalanching in the axis. For a particular day, the significance level of individual parameters is first determined according to the developed criterion. The average level of significance then indicates the probability of avalanching in the axis on that day. A critical limit of probability based on the data of past occurrences, helps to put that particular day in the class of avalanche or non-avalanche day. The values of the individual variables, then predict the likely nature of avalanche in terms of type and size based on the pre-identified ranges.

  4. Micro flame-based detector suite for universal gas sensing.

    Energy Technology Data Exchange (ETDEWEB)

    Hamilton, Thomas Warren; Washburn, Cody M.; Moorman, Matthew Wallace; Manley, Robert George; Lewis, Patrick Raymond; Miller, James Edward; Clem, Paul Gilbert; Shelmidine, Gregory J.; Manginell, Ronald Paul; Okandan, Murat

    2005-11-01

    A microflame-based detector suit has been developed for sensing of a broad range of chemical analytes. This detector combines calorimetry, flame ionization detection (FID), nitrogen-phosphorous detection (NPD) and flame photometric detection (FPD) modes into one convenient platform based on a microcombustor. The microcombustor consists in a micromachined microhotplate with a catalyst or low-work function material added to its surface. For the NPD mode a low work function material selectively ionizes chemical analytes; for all other modes a supported catalyst such as platinum/alumina is used. The microcombustor design permits rapid, efficient heating of the deposited film at low power. To perform calorimetric detection of analytes, the change in power required to maintain the resistive microhotplate heater at a constant temperature is measured. For FID and NPD modes, electrodes are placed around the microcombustor flame zone and an electrometer circuit measures the production of ions. For FPD, the flame zone is optically interrogated to search for light emission indicative of deexcitation of flame-produced analyte compounds. The calorimetric and FID modes respond generally to all hydrocarbons, while sulfur compounds only alarm in the calorimetric mode, providing speciation. The NPD mode provides 10,000:1 selectivity of nitrogen and phosphorous compounds over hydrocarbons. The FPD can distinguish between sulfur and phosphorous compounds. Importantly all detection modes can be established on one convenient microcombustor platform, in fact the calorimetric, FID and FPD modes can be achieved simultaneously on only one microcombustor. Therefore, it is possible to make a very universal chemical detector array with as little as two microcombustor elements. A demonstration of the performance of the microcombustor in each of the detection modes is provided herein.

  5. Recent technological developments on LGAD and iLGAD detectors for tracking and timing applications

    Science.gov (United States)

    Pellegrini, G.; Baselga, M.; Carulla, M.; Fadeyev, V.; Fernández-Martínez, P.; García, M. Fernández; Flores, D.; Galloway, Z.; Gallrapp, C.; Hidalgo, S.; Liang, Z.; Merlos, A.; Moll, M.; Quirion, D.; Sadrozinski, H.; Stricker, M.; Vila, I.

    2016-09-01

    This paper reports the latest technological development on the Low Gain Avalanche Detector (LGAD) and introduces a new architecture of these detectors called inverse-LGAD (iLGAD). Both approaches are based on the standard Avalanche Photo Diodes (APD) concept, commonly used in optical and X-ray detection applications, including an internal multiplication of the charge generated by radiation. The multiplication is inherent to the basic n++-p+-p structure, where the doping profile of the p+ layer is optimized to achieve high field and high impact ionization at the junction. The LGAD structures are optimized for applications such as tracking or timing detectors for high energy physics experiments or medical applications where time resolution lower than 30 ps is required. Detailed TCAD device simulations together with the electrical and charge collection measurements are presented through this work.

  6. Recent Technological Developments on LGAD and iLGAD Detectors for Tracking and Timing Applications

    CERN Document Server

    Pellegrini, G; Carulla, M.; Fadeyev, V.; Fernandez-Martinez, P.; Fernandez-Garcia, M.; Flores, D.; Galloway, Z.; Gallrapp, C.; Hidalgo, S.; Liang, Z.; Merlos, A.; Moll, M.; Quirion, D.; Sadrozinski, H.; Stricker, M.; Vila, I.

    2016-01-01

    This paper reports the last technological development on the Low Gain Avalanche Detector (LGAD) and introduces a new architecture of these detectors called inverse-LGAD (iLGAD). Both approaches are based on the standard Avalanche Photo Diodes (APD) concept, commonly used in optical and X-ray detection applications, including an internal multiplication of the charge generated by radiation. The multiplication is inherent to the basic n++-p+-p structure, where the doping profile of the p+ layer is optimized to achieve high field and high impact ionization at the junction. The LGAD structures are optimized for applications such as tracking or timing detectors for high energy physics experiments or medical applications where time resolution lower than 30 ps is required. Detailed TCAD device simulations together with the electrical and charge collection measurements are presented through this work.

  7. Correcting for accidental correlations in saturated avalanche photodiodes.

    Science.gov (United States)

    Grieve, J A; Chandrasekara, R; Tang, Z; Cheng, C; Ling, A

    2016-02-22

    In this paper we present a general method for estimating rates of accidental coincidence between a pair of single photon detectors operated within their saturation regimes. By folding the effects of recovery time of both detectors and the detection circuit into an "effective duty cycle" we are able to accomodate complex recovery behaviour at high event rates. As an example, we provide a detailed high-level model for the behaviour of passively quenched avalanche photodiodes, and demonstrate effective background subtraction at rates commonly associated with detector saturation. We show that by post-processing using the updated model, we observe an improvement in polarization correlation visibility from 88.7% to 96.9% in our experimental dataset. This technique will be useful in improving the signal-to-noise ratio in applications which depend on coincidence measurements, especially in situations where rapid changes in flux may cause detector saturation. PMID:26907016

  8. High-density avalanche chambers for positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Manfrass, P.; Enghardt, W.; Fromm, W.D.; Wohlfarth, D.; Hohmuth, K.

    1988-12-15

    A positron tomograph for radiopharmaceutical and medical research is under construction. In its final stage it will cover six high-density avalanche chambers (HIDAC) in a hexagonal arrangement. Each detector with a sensitive area of 50x28 cm/sup 2/ will consist of a stack of four pairs of multihole photon-to-electron converters with a multiwire proportional counter (MWPC) in between. An experimental investigation of detector properties as time and spatial resolutions as well as detector efficiency in dependence to converter structure, electric field strength and counting gas mixture preceded the final design of these detectors. Results of these studies are outlined. Furthermore, longitudinal tomograms taken with a stationary test camera are presented.

  9. Low-temperature-dependent property in an avalanche photodiode based on GaN/AlN periodically-stacked structure

    Science.gov (United States)

    Zheng, Jiyuan; Wang, Lai; Yang, Di; Yu, Jiadong; Meng, Xiao; Hao, Zhibiao; Sun, Changzheng; Xiong, Bing; Luo, Yi; Han, Yanjun; Wang, Jian; Li, Hongtao; Li, Mo; Li, Qian

    2016-01-01

    In ultra-high sensitive APDs, a vibrate of temperature might bring a fatal decline of the multiplication performance. Conventional method to realize a temperature-stable APD focuses on the optimization of device structure, which has limited effects. While in this paper, a solution by reducing the carrier scattering rate based on an GaN/AlN periodically-stacked structure (PSS) APD is brought out to improve temperature stability essentially. Transport property is systematically investigated. Compared with conventional GaN homojunction (HJ) APDs, electron suffers much less phonon scatterings before it achieves ionization threshold energy and more electrons occupy high energy states in PSS APD. The temperature dependence of ionization coefficient and energy distribution is greatly reduced. As a result, temperature stability on gain is significantly improved when the ionization happens with high efficiency. The change of gain for GaN (10 nm)/AlN (10 nm) PSS APD from 300 K to 310 K is about 20% lower than that for HJ APD. Additionally, thicker period length is found favorable to ionization coefficient ratio but a bit harmful to temperature stability, while increasing the proportion of AlN at each period in a specific range is found favorable to both ionization coefficient ratio and temperature stability. PMID:27775088

  10. Sediment Transport by Spring Avalanches in the Southern Swiss Alps

    Science.gov (United States)

    Egloff, J. M.; Hunziker, M.; Moore, J. R.; Christen, M.

    2010-12-01

    Dense wet-snow avalanches breaking through to the base of the snow pack or overriding snow-free surfaces can entrain basal material and act as important agents of sediment transport in steep Alpine catchments. As part of an ongoing study, we investigated two debris fans in the Matter Valley of southern Switzerland during spring 2009 and 2010, with emphasis on quantifying avalanche sediment transport. Deposited debris ranged from soil parcels and plant material to cobbles and boulders greater than 1 m3. Large boulders were generally angular and fresh with clear signs of recent impacts. The seasonal sediment load transported by avalanches was estimated at one fan by sampling the debris content within a number of representative areas, and then extrapolating the cumulative volume. Results reveal a total transported sediment volume of ~150 m3 in 2009 and ~15 m3 in 2010, which likely reflects varying snowfall and avalanche frequency between years. When distributed over the deposition area on the fan, these results imply an average accumulated sediment thickness of 12 mm in 2009 and 3 mm in 2010. Calculated catchment-wide erosion rates are ~0.1 mm/yr for 2009 and ~0.01 mm/yr for 2010. Cross-sections through avalanche debris revealed that transported sediment generally resides on top of the snow surface. As the avalanches melt, entrained sediment is set down gently, often resulting in precariously balanced boulders and rows of blocks perched on the walls of the fan’s channels. In flat lying areas, snowmelt resulted in sparse sediment deposits with no clear structure or sorting. Observations show that the fan surface is usually protected from erosion by snow and older avalanche deposits, which provide a smooth gliding plane for new events. Within the bedrock gulley adjacent to the fan, and in the avalanche source region above, signs of abrasive wear were evident on exposed bedrock surfaces. These include rounded and scoured bedrock, fresh signs of boulder impacts, and

  11. Technical Proposal for the ALICE START Fast Timing Detector Based on Fine-Mesh Phototubes

    CERN Document Server

    Kaplin, V A; CERN. Geneva; Loginov, V A; Strikhanov, M N; Gavrilov, Yu K; Filippov, S N; Kurepin, A B; Mayevskaya, A I

    1997-01-01

    Technical Proposal for the ALICE START Fast Timing Detector Based on Fine-Mesh Phototubes A scintillation detector based on fine-mesh phototubes with good timing proporties ( ~ 50 ps) is proposed as a complementary detector for two existing options of the ALICE Forward Multiplicity Detector. Experimental results show high time resolution (up to 35 ps) and high gain in a magnetic field up to 0.5 T of fine-mesh Russian phototubes FEU-527. The proposed detector consists of two arrays of scintillation (or Cherenkov) counters, 24 counters each. The Monte-Carlo simulations made for the proposed design of the detector for p-p collisions give the average efficiency of the detector about 80%. The physical characteristics of the proposed detector are compared with those expected for the MCP version of the FMD.

  12. BJT-based detector on high-resistivity silicon with integrated biasing structure

    Energy Technology Data Exchange (ETDEWEB)

    Verzellesi, G. [Department of Information Engineering, University of Modena and Reggio Emilia, via Vignolese 905, 41100 Modena (Italy) and INFM Modena, and INFN Bologna (Italy)]. E-mail: verzellesi.giovanni@unimore.it; Batignani, G. [University of Pisa, Department of Physics ' E. Fermi' , and INFN Pisa, Largo Pontecorvo 3, 56127 Pisa (Italy); Bettarini, S. [University of Pisa, Department of Physics ' E. Fermi' , and INFN Pisa, Largo Pontecorvo 3, 56127 Pisa (Italy); Boscardin, M. [ITC-irst, Microsystems Division, via Sommarive, 18, 38050 Povo di Trento (Italy); Bosisio, L. [University of Trieste, Department of Physics, and INFN Trieste, via A. Valerio 2, Trieste, 34127 (Italy); Dalla Betta, G.-F. [University of Trento, Department of Information and Communication Technology, via Sommarive 14, 38050 Povo di Trento (Italy); Giacomini, G. [University of Trieste, Department of Physics, and INFN Trieste, via A. Valerio 2, Trieste, 34127 (Italy); Piemonte, C. [ITC-irst, Microsystems Division, via Sommarive, 18, 38050 Povo di Trento (Italy)

    2006-11-01

    A novel method for biasing phototransistor-based radiation detectors on high-resistivity Si is presented, that relies on the integration into the detector base of a pnp transistor acting as a current source. The proposed approach can be extended in a natural way to the biasing of npn detector arrays, allowing different detectors to be biased at the same quiescent current, by connecting all the biasing pnp transistors with a diode-connected reference transistor (integrated onto the same chip), so that they form a current-mirror circuit. Relying on two-dimensional numerical device simulations, several test structures have been designed and fabricated, including single BJT detectors and detector arrays with pnp biasing transistors connected in the current-mirror configuration. The electrical characterization of fabricated structures shows that both single detectors and detector arrays are operational and behave in good agreement with simulations, thus demonstrating the feasibility of the proposed approach.

  13. Novel micropixel avalanche photodiodes (MAPD) with superhigh pixel density

    International Nuclear Information System (INIS)

    In many detectors based on scintillators the photomultiplier tubes (PMTs) are used as photodetectors. At present photodiodes are finding wide application. Solid state photodetectors allow operation in strong magnetic fields that are often present in applications, e.g., some calorimeters operating near magnets, combined PET and MRT, etc. The photon detection efficiency (PDE) of photodiodes may reach values a few times higher than that of PMTs. Also, they are rigid, compact and have relatively low operating voltage. In the last few years Micropixel Avalanche PhotoDiodes (MAPDs) have been developed and started to be used. The MAPD combines a lot of advantages of semiconductor photodetectors and has a high gain, which is close to that of the PMT. Yet, they have some disadvantages, and one of them is a limited dynamic range that corresponds to a total number of pixels. The novel deep microwell MAPD with high pixel density produced by Zecotek Company partially avoids this disadvantage. In this paper characteristics of these photodetectors are presented in comparison with the PMT characteristics. The results refer to measurements of the gain, PDE, cross-talks, photon counting and applications: beam test results of two different 'Shashlyk' EM calorimeters for COMPASS (CERN) and NICA-MPD (JINR) with the MAPD readout and a possibility of using the MAPD in PET

  14. A compact gas-filled avalanche counter for DANCE

    Science.gov (United States)

    Wu, C. Y.; Chyzh, A.; Kwan, E.; Henderson, R. A.; Gostic, J. M.; Carter, D.; Bredeweg, T. A.; Couture, A.; Jandel, M.; Ullmann, J. L.

    2012-12-01

    A compact gas-filled avalanche counter for the detection of fission fragments was developed for a highly segmented 4π γ-ray calorimeter, namely the Detector for Advanced Neutron Capture Experiments located at the Lujan Center of the Los Alamos Neutron Science Center. It has been used successfully for experiments with 235U, 238Pu, 239Pu, and 241Pu isotopes to provide a unique signature to differentiate the fission from the competing neutron-capture reaction channel. It was also used to study the spontaneous fission in 252Cf. The design and performance of this avalanche counter for targets with extreme α-decay rate up to ˜2.4×108/s are described.

  15. A compact gas-filled avalanche counter for DANCE

    Energy Technology Data Exchange (ETDEWEB)

    Wu, C.Y., E-mail: wu24@llnl.gov [Lawrence Livermore National Laboratory, Livermore, CA 94551 (United States); Chyzh, A.; Kwan, E.; Henderson, R.A.; Gostic, J.M.; Carter, D. [Lawrence Livermore National Laboratory, Livermore, CA 94551 (United States); Bredeweg, T.A.; Couture, A.; Jandel, M.; Ullmann, J.L. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2012-12-01

    A compact gas-filled avalanche counter for the detection of fission fragments was developed for a highly segmented 4{pi} {gamma}-ray calorimeter, namely the Detector for Advanced Neutron Capture Experiments located at the Lujan Center of the Los Alamos Neutron Science Center. It has been used successfully for experiments with {sup 235}U, {sup 238}Pu, {sup 239}Pu, and {sup 241}Pu isotopes to provide a unique signature to differentiate the fission from the competing neutron-capture reaction channel. It was also used to study the spontaneous fission in {sup 252}Cf. The design and performance of this avalanche counter for targets with extreme {alpha}-decay rate up to {approx}2.4 Multiplication-Sign 10{sup 8}/s are described.

  16. A compact gas-filled avalanche counter for DANCE

    International Nuclear Information System (INIS)

    A compact gas-filled avalanche counter for the detection of fission fragments was developed for a highly segmented 4π γ-ray calorimeter, namely the Detector for Advanced Neutron Capture Experiments located at the Lujan Center of the Los Alamos Neutron Science Center. It has been used successfully for experiments with 235U, 238Pu, 239Pu, and 241Pu isotopes to provide a unique signature to differentiate the fission from the competing neutron-capture reaction channel. It was also used to study the spontaneous fission in 252Cf. The design and performance of this avalanche counter for targets with extreme α-decay rate up to ∼2.4×108/s are described.

  17. Optimisation and Characterisation of Glass RPC for India-based Neutrino Observatory Detectors

    OpenAIRE

    Kanishka, R.; Bhatnagar, Vipin; Indumathi, D.

    2016-01-01

    The proposed magnetised Iron CALorimeter detector (ICAL) to be built in the India-based Neutrino Observatory (INO) laboratory aims to detect atmospheric muon neutrinos. In order to achieve improved physics results, the constituent components of the detector must be fully understood by proper characterisation and optimisation of various parameters. Resistive Plate Chambers (RPCs) are the active detector elements in the ICAL detector and can be made of glass or bakelite. The number of RPCs requ...

  18. Accelerometer-Based Event Detector for Low-Power Applications

    Directory of Open Access Journals (Sweden)

    József Smidla

    2013-10-01

    Full Text Available In this paper, an adaptive, autocovariance-based event detection algorithm is proposed, which can be used with micro-electro-mechanical systems (MEMS accelerometer sensors to build inexpensive and power efficient event detectors. The algorithm works well with low signal-to-noise ratio input signals, and its computational complexity is very low, allowing its utilization on inexpensive low-end embedded sensor devices. The proposed algorithm decreases its energy consumption by lowering its duty cycle, as much as the event to be detected allows it. The performance of the algorithm is tested and compared to the conventional filter-based approach. The comparison was performed in an application where illegal entering of vehicles into restricted areas was detected.

  19. Illicit material detector based on gas sensors and neural networks

    Science.gov (United States)

    Grimaldi, Vincent; Politano, Jean-Luc

    1997-02-01

    In accordance with its missions, le Centre de Recherches et d'Etudes de la Logistique de la Police Nationale francaise (CREL) has been conducting research for the past few years targeted at detecting drugs and explosives. We have focused our approach of the underlying physical and chemical detection principles on solid state gas sensors, in the hope of developing a hand-held drugs and explosives detector. The CREL and Laboratory and Scientific Services Directorate are research partners for this project. Using generic hydrocarbon, industrially available, metal oxide sensors as illicit material detectors, requires usage precautions. Indeed, neither the product's concentrations, nor even the products themselves, belong to the intended usage specifications. Therefore, the CREL is currently investigating two major research topics: controlling the sensor's environment: with environmental control we improve the detection of small product concentration; determining detection thresholds: both drugs and explosives disseminate low gas concentration. We are attempting to quantify the minimal concentration which triggers detection. In the long run, we foresee a computer-based tool likely to detect a target gas in a noisy atmosphere. A neural network is the suitable tool for interpreting the response of heterogeneous sensor matrix. This information processing structure, alongside with proper sensor environment control, will lessen the repercussions of common MOS sensor sensitivity characteristic dispersion.

  20. A prototype coordinate detector based on granulated thin-walled drift tubes

    CERN Document Server

    Bazylev, S N; Tikhomirov, V O; Davkov, K I; Gregor, I; Smirnov, S Y; Senger, P; Shutov, A V; Slepnev, I V; Myalkovskiy, V V; Naumann, L; Mouraviev, S V; Zhukov, I A; Peshekhonov, V D; Russakovich, N A; Rufanov, I A; Rembser, C

    2011-01-01

    A prototype detector based on thin-walled segmented tubes has been developed and its parameters have been studied. The detector contains 360 registration channels with a straw diameter of 4 mm. The prototype' granularity is 4 cm(2) and the length of insensitive region due to straw internal elements is less than 5\\% of its full sensitive area. Deterioration of the spatial resolution near these elements is observed for 1.0\\% of the detector sensitive area. The time and spatial parameters of the detector do not differ from those of conventional tracking detectors based on drift tubes. (C) 2011 Published by Elsevier B.V.

  1. Hole-Initiated-Avalanche, Linear-Mode, Single-Photon-Sensitive Avalanche Photodetector with Reduced Excess Noise and Low Dark Count Rate Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A radiation hard, single photon sensitive InGaAs avalanche photodiode (APD) receiver technology will be demonstrated useful for long range space based optical...

  2. Geometrical properties of avalanches in self-organized critical models of solar flares

    International Nuclear Information System (INIS)

    We investigate the geometrical properties of avalanches in self-organized critical models of solar flares. Traditionally, such models differ from the classical sandpile model in their formulation of stability criteria in terms of the curvature of the nodal field, and belong to a distinct universality class. With a view toward comparing these properties to those inferred from spatially and temporally resolved flare observations, we consider the properties of avalanche peak snapshots, time-integrated avalanches in two and three dimensions, and the two-dimensional projections of the latter. The nature of the relationship between the avalanching volume and its projected area is an issue of particular interest in the solar flare context. Using our simulation results we investigate this relationship, and demonstrate that proper accounting of the fractal nature of avalanches can bring into agreement hitherto discrepant results of observational analyses based on simple, nonfractal geometries for the flaring volume

  3. Spectrum Sensor Hardware Implementation Based on Cyclostationary Feature Detector

    Directory of Open Access Journals (Sweden)

    Jussi Ryynänen

    2011-03-01

    Full Text Available Cognitive radios utilize spectrum sensors to provide information about the surrounding radio environment. This enables cognitive radios to communicate at the same frequency bands with existing (primary radio systems, and thereby improve the utilization of spectral resources. Furthermore, the spectrum sensor must be able to guarantee that the cognitive radio devices do not interfere with the primary system transmissions. This paper describes a hardware implementation of a spectrum sensor based on cyclostationary feature detector, which has an improved detection performance achieved by decimation of the cyclic spectrum. Decimation also provides a simple way to control detection time and, therefore, allows trading the detection time to better probability of detection and vice versa. Implementation complexity in terms of power consumption and silicon area for a 65 nm CMOS process is evaluated. Measured detection performance is presented and detection of a 802.11g WLAN signal through air interface is demonstrated.

  4. Research on Stealthy Headphone Detector Based on Geomagnetic Sensor

    Directory of Open Access Journals (Sweden)

    Liu Ya

    2016-01-01

    Full Text Available A kind of stealth headphone detector based on geomagnetic sensor has been developed to deal with the stealth headphones which are small, extremely stealthy and hard to detect. The U.S. PNI geomagnetic sensor is chosen to obtain magnetic field considering the strong magnetic performance of stealth headphones. The earth’s magnetic field at the geomagnetic sensor is eliminated by difference between two geomagnetic sensors, and then weak variations of magnetic field is detected. STM8S103K2 is chosen as the central controlling chip, which is connected to LED, buzzer and LCD 1602. As shown by the experimental results, the probe is not liable to damage by the magnetic field and the developed device has high sensitivity, low False Positive Rate (FAR and satisfactory reliability.

  5. A method to precisely identify the afterpulses when using the S9717 avalanche photodiode

    Science.gov (United States)

    Rusu, Alexandru; Rusu, Lucian

    2015-12-01

    The detection ratio of an avalanche photodiode (APD) biased in Geiger-mode increases versus the excess voltage; the afterpulsing rate increases too. The last one can be reduced by inserting an artificial dead time and accepting a lower measuring top rate. So, in order to tune a single-photon detector system, it is necessary to exactly identify afterpulses and measure their rate; the experimental results are presented. When using the S9717 APD in Geiger-mode, the cathode to ground voltage waveform reveals the existence of a particular sequence of pulses: a usual one followed, within 1μs, by a least one appearing to have been generated for negative excess voltage values. All these characteristics are the signature of the afterpulsing generation. Based on this observation, we were able to precisely measure the afterpulsing rate.

  6. A method to precisely identify the afterpulses when using the S9717 avalanche photodiode

    Energy Technology Data Exchange (ETDEWEB)

    Rusu, Alexandru, E-mail: alrusu@nipne.ro; Rusu, Lucian [“Horia Hulubei” National Institute for Physics and Nuclear Engineering, Reactorului Street, No. 34, City Măgurele, jud. Ilfov, POB 077125 (Romania)

    2015-12-07

    The detection ratio of an avalanche photodiode (APD) biased in Geiger-mode increases versus the excess voltage; the afterpulsing rate increases too. The last one can be reduced by inserting an artificial dead time and accepting a lower measuring top rate. So, in order to tune a single-photon detector system, it is necessary to exactly identify afterpulses and measure their rate; the experimental results are presented. When using the S9717 APD in Geiger-mode, the cathode to ground voltage waveform reveals the existence of a particular sequence of pulses: a usual one followed, within 1μs, by a least one appearing to have been generated for negative excess voltage values. All these characteristics are the signature of the afterpulsing generation. Based on this observation, we were able to precisely measure the afterpulsing rate.

  7. Joint preprocesser-based detector for cooperative networks with limited hardware processing capability

    KAUST Repository

    Abuzaid, Abdulrahman I.

    2015-02-01

    In this letter, a joint detector for cooperative communication networks is proposed when the destination has limited hardware processing capability. The transmitter sends its symbols with the help of L relays. As the destination has limited hardware, only U out of L signals are processed and the energy of the remaining relays is lost. To solve this problem, a joint preprocessing based detector is proposed. This joint preprocessor based detector operate on the principles of minimizing the symbol error rate (SER). For a realistic assessment, pilot symbol aided channel estimation is incorporated for this proposed detector. From our simulations, it can be observed that our proposed detector achieves the same SER performance as that of the maximum likelihood (ML) detector with all participating relays. Additionally, our detector outperforms selection combining (SC), channel shortening (CS) scheme and reduced-rank techniques when using the same U. Our proposed scheme has low computational complexity.

  8. Supersensitive avalanche silicon drift photodetector

    International Nuclear Information System (INIS)

    Physical principles of performance and main characteristics of a novel avalanche photodetector developed on the basis of MOS (metal-oxide-silicon) technology are presented. The photodetector contains a semitransparent gate electrode and a drain contact to provide a drift of multiplied charge carriers along the semiconductor surface. A high gain (more than 104) of the photocurrent was achieved due to the local negative feedback effect realized on the Si -- SiO2 boundary. Special attention is paid to the possibilities of the development of a supersensitive avalanche CCD (charge-coupled device) for the detection of individual photons in visible and ultraviolet spectral regions. The experimental results obtained with a two-element CCD prototype are discussed. (author)

  9. Multi scale Harris corner detector based on Differential Morphological Decomposition

    OpenAIRE

    GUEGUEN LIONEL; Pesaresi, Martino

    2010-01-01

    In this paper, a novel method for multi scale corner analysis and detection is presented. First, stateof-the-art Harris–Laplace corner detector is reminded, which benefits from linear scale-space analysis. Secondly, a non-linear scale-space transform, namely Differential Morphological Decomposition, is described. This multi-scale transform is used jointly with the Harris corner indicator to build a new multi scale corner detector. Both corner detectors are visually assessed on synthet...

  10. MDRAP - a MATLAB-based detector response analysis package

    International Nuclear Information System (INIS)

    An analysis program has been developed, in the MATLAB environment, for determining in-core flux detector dynamic response characteristics from a combined knowledge of the local detector flux and measured detector output. Critical to the program is an accurate estimate of the local detector flux. The estimated local detector flux is input to a detailed model of the detector and its electronic compensators; the model output is compared with the recorded signal. The model of the detector is then iteratively adjusted to minimize the mean square error between the output of the model and the recorded signal. The process is completely automated, requiring no manual input by the code user. The program has been used on both Pt-clad and vanadium detectors for the Point Lepreau Nuclear Generating Station for various power rundown tests. This paper describes the code and presents results from the analysis of Pt-clad detectors with data from the 1997 shutdown system (SDS1) Trip Test at Pt. Lepreau. (author)

  11. Fission-fragment detector for DANCE based on thin scintillating films

    Science.gov (United States)

    Rusev, G.; Roman, A. R.; Daum, J. K.; Springs, R. K.; Bond, E. M.; Jandel, M.; Baramsai, B.; Bredeweg, T. A.; Couture, A.; Favalli, A.; Ianakiev, K. D.; Iliev, M. L.; Mosby, S.; Ullmann, J. L.; Walker, C. L.

    2015-12-01

    A fission-fragment detector based on thin scintillating films has been built to serve as a trigger/veto detector in neutron-induced fission measurements at DANCE. The fissile material is surrounded by scintillating films providing 4 π detection of the fission fragments. The scintillation photons were registered with silicon photomultipliers. A measurement of the 235U (n , f) reaction with this detector at DANCE revealed a correct time-of-flight spectrum and provided an estimate for the efficiency of the prototype detector of 11.6(7)%. Design and test measurements with the detector are described.

  12. Avalanches, Scaling and Coherent Noise

    OpenAIRE

    Newman, M. E. J.; Sneppen, Kim

    1996-01-01

    We present a simple model of a dynamical system driven by externally-imposed coherent noise. Although the system never becomes critical in the sense of possessing spatial correlations of arbitrarily long range, it does organize into a stationary state characterized by avalanches with a power-law size distribution. We explain the behavior of the model within a time-averaged approximation, and discuss its potential connection to the dynamics of earthquakes, the Gutenberg-Richter law, and to rec...

  13. Self-aligned multi-channel superconducting nanowire avalanche photodetector

    CERN Document Server

    Cheng, Risheng; Ma, Xiaosong; Fan, Linran; Fong, King Y; Poot, Menno; Tang, Hong X

    2016-01-01

    We describe a micromachining process to allow the coupling of an array of single-mode telecommunication fibers to individual superconducting nanowire single photon detectors (SNSPDs). As proof of principle, we show the integration of four detectors on the same silicon chip, including two standard single-section nanowire detectors and two superconducting nanowire avalanche photodetectors (SNAPs) with modified series structure without external inductor, and their performances are compared. The SNAP shows saturated system detection efficiency of 16% while the dark count rate is less than 20 Hz, without the use of photon-recycling reflectors. The SNAP also demonstrates doubled signal-to-noise ratio, reduced reset time (~ 4.9 ns decay time) and improved timing jitter (62 ps FWHM) compared to standard SNSPDs.

  14. Practical photon number detection with electric field-modulated silicon avalanche photodiodes.

    Science.gov (United States)

    Thomas, O; Yuan, Z L; Shields, A J

    2012-01-01

    Low-noise single-photon detection is a prerequisite for quantum information processing using photonic qubits. In particular, detectors that are able to accurately resolve the number of photons in an incident light pulse will find application in functions such as quantum teleportation and linear optics quantum computing. More generally, such a detector will allow the advantages of quantum light detection to be extended to stronger optical signals, permitting optical measurements limited only by fluctuations in the photon number of the source. Here we demonstrate a practical high-speed device, which allows the signals arising from multiple photon-induced avalanches to be precisely discriminated. We use a type of silicon avalanche photodiode in which the lateral electric field profile is strongly modulated in order to realize a spatially multiplexed detector. Clearly discerned multiphoton signals are obtained by applying sub-nanosecond voltage gates in order to restrict the detector current. PMID:22273682

  15. Townsend coefficients of gases in avalanche counters

    International Nuclear Information System (INIS)

    Though much work has been done by many authors in the last few years in the development and application of avalanche counters for ion radiation, it is based upon values of the Townsend coefficients as the essential gas parameter, which were determined many years ago for much lower reduced field strengths F/p than prevail in such counters. Therefore absolute determinations of α in vapours of methyl alcohol, cyclohexane, acetone, and n-heptene were performed under original conditions of avalanche counters. The values obtained do not differ by more than 30%-50% from the former values indeed, extrapolated over F/p for the first three mentioned substances, but the amounts of A and B in the usual representation α/p=A exp(-B(F/p)) are much greater for the stronger reduced fields. This is of importance for such counter properties as the dependence of pulse heights on pressure, voltage, electrode distance etc., which are governed by other combinations of A and B than α/p itself. A comparison of results for different ionic radiations shows a marked influence of the primary ionization density along the particle tracks which is hard to explain. (Auth.)

  16. Comparison of seismic and infrasound wave fields generated by snow avalanches

    Science.gov (United States)

    Suriñach, Emma; Tapia, Mar; Pérez-Guillén, Cristina; Khazaradze, Giorgi; Roig, Pere

    2016-04-01

    Snow avalanches are a source of waves that are transmitted through the ground and the air. These wave fields are detected by seismic and infrasound sensors. During the winter seasons 2008 -2016, a good quality database of avalanches was obtained at the VdlS test site with an accurate instrumentation. These avalanches were both natural and artificially triggered and were of varying types and sizes. Distances involved were 0.5 -3 km. Seismic signals were acquired using three seismometers (3-components, 1Hz) spaced 600 m apart along the avalanche track. One infrasound sensor (0.1Hz) and one seismometer (3-components, 1Hz) were placed one next to the other with a common base of time on the slope opposite the path. The database obtained enables us to compare the different signals generated. Differences in the frequency content and shape of the signals depending on the type and size of the avalanche are detected. A clear evolution of the recorded seismic signals along the path is observed. The cross correlation of the infrasound and seismic signals generated by the avalanches allows us to determine different characteristics for powder, transitional and wet avalanches concerning their wave fields. The joint analysis of infrasound and seismic waves enables us to obtain valuable information about the internal parts of the avalanche as a source of each wave field. This study has repercussions on avalanche dynamics and on the selection of the appropriate avalanche detection system. This study is supported by the Spanish Ministry of Science and Innovation project CHARMA: CHAracterization and ContRol of MAss Movements. A Challenge for Geohazard Mitigation (CGL2013-40828-R), and RISKNAT group (2014GR/1243).

  17. Avalanche ecology and large magnitude avalanche events: Glacier National Park, Montana, USA

    Science.gov (United States)

    Fagre, Daniel B.; Peitzsch, Erich H.

    2010-01-01

    Large magnitude snow avalanches play an important role ecologically in terms of wildlife habitat, vegetation diversity, and sediment transport within a watershed. Ecological effects from these infrequent avalanches can last for decades. Understanding the frequency of such large magnitude avalanches is also critical to avalanche forecasting for the Going-to-the-Sun Road (GTSR). In January 2009, a large magnitude avalanche cycle occurred in and around Glacier National Park, Montana. The study site is the Little Granite avalanche path located along the GTSR. The study is designed to quantify change in vegetative cover immediately after a large magnitude event and document ecological response over a multi-year period. GPS field mapping was completed to determine the redefined perimeter of the avalanche path. Vegetation was inventoried using modified U.S. Forest Service Forest Inventory and Analysis plots, cross sections were taken from over 100 dead trees throughout the avalanche path, and an avalanche chronology was developed. Initial results indicate that the perimeter of this path was expanded by 30%. The avalanche travelled approximately 1200 vertical meters and 3 linear kilometers. Stands of large conifers as old as 150 years were decimated by the avalanche, causing a shift in dominant vegetation types in many parts of the avalanche path. Woody debris is a major ground cover up to 3 m in depth on lower portions of the avalanche path and will likely affect tree regrowth. Monitoring and measuring the post-avalanche vegetation recovery of this particular avalanche path provides a unique dataset for determining the ecological role of avalanches in mountain landscapes.

  18. MCP-based detector some results and perspectives

    CERN Document Server

    Patarakin, O O; Strepetov, A N; Turbin, E V; Sinitsin, V I; Kartamushev, A A

    1997-01-01

    The timing resolution of photomultiplier tubes (PMT) based on shevron-type microchannel plates (MCP) has been studied inmagnetic fields. The same timingresolution with and without a longitudinal magnetic field up to 2.0 kGwas obtained as = 85 ± 2 ps. It is shown that an increase of timing resolution in this magnetic field does not exceed25 ps (upper limit). The timing resolution of = 31 ± 2 pswas obtained for narrow (10resolution) amplitude spectrumfrom Corone discharge. The counting rate of MCP-based detector was studied in function of the direction of the magnetic field.The spatial and timing resolution for the MCP-based PMT were obtained using laser pulses as well. With laser pulses of 0.3 ns a timing resolution of ≅ 450 ps was obtained. Taking into account the amplitude correction narrows to 140 ps. Using 100 fs-laser with the standard constant fractiondiscriminator gives a timing resolution from 20 to 40 ps depending on the read-out MCP region.The perspectives of using...

  19. Avalanche Dynamics in Wet Granular Materials

    OpenAIRE

    Tegzes, P.; Vicsek, T.; P. Schiffer

    2002-01-01

    We have studied the dynamics of avalanching wet granular media in a rotating drum apparatus. Quantitative measurements of the flow velocity and the granular flux during avalanches allow us to characterize novel avalanche types unique to wet media. We also explore the details of viscoplastic flow (observed at the highest liquid contents) in which there are lasting contacts during flow, leading to coherence across the entire sample. This coherence leads to a velocity independent flow depth at h...

  20. Scintillation neutron detectors based on solid-state photomultipliers and lightguides

    Energy Technology Data Exchange (ETDEWEB)

    Litvin, V. S., E-mail: vlitvin@inr.ru; Marin, V. N.; Karaevsky, S. K.; Trunov, D. N.; Axenov, S. N.; Stolyarov, A. A.; Sadykov, R. A. [Russian Academy of Sciences, Institute for Nuclear Research (Russian Federation)

    2016-01-15

    Neutron detectors based on scintillation screens ZnS(Ag)/LiF and solid-state photomultipliers have been developed. Lightguides are used to collect light. The application of a coincidence scheme provides a low dark count and a neutron detection efficiency as high as 70%. A scheme of x-y neutron detector based on wavelength shifting fibers is also proposed. Tests of the proposed versions of detectors in a neutron beam have shown their efficiency.

  1. The Design of a Low Power Floating Gate Based Phase Frequency Detector and Charge Pump Implementation

    OpenAIRE

    Md. Monirul Islam; Ankit Shivhare

    2013-01-01

    A simple new architecture of phase frequency detector with low power and low phase noise is presented in this paper. The proposed phase frequency detector is based on floating gate, consist of 4 transistors including one floating gate pMOS and one floating gate nMOS constructed with two GDI (gate diffusion input) cells and maintain main characteristics of conventional phase frequency detector in 180 nm technology. Floating gate based methodology reduced the power of phase frequenc...

  2. Scintillation neutron detectors based on solid-state photomultipliers and lightguides

    International Nuclear Information System (INIS)

    Neutron detectors based on scintillation screens ZnS(Ag)/LiF and solid-state photomultipliers have been developed. Lightguides are used to collect light. The application of a coincidence scheme provides a low dark count and a neutron detection efficiency as high as 70%. A scheme of x-y neutron detector based on wavelength shifting fibers is also proposed. Tests of the proposed versions of detectors in a neutron beam have shown their efficiency

  3. Double Screening Tests of the CMS ECAL Avalanche Photodiodes

    CERN Document Server

    Deiters, Konrad; Renker, Dieter; Sakhelashvili, Tariel; Britvitch, Ilia; Kuznetsov, Andrey; Musienko, Yuri; Singovsky, Alexander

    2005-01-01

    Specially developed avalanche photo-diodes (APDs) will be used to measure the light from the 61,200 lead tungstate crystals in the barrel part of the CMS electromagnetic calorimeter. To ensure the reliability over the lifetime of the detector, every APD is screened by irradiation and burn-in before it is accepted for CMS. As part of the establishment of the screening procedure and to determine its effectiveness, a large number of APDs were screened twice. The results of these tests suggest that the required reliability will be achieved.

  4. Characterization of the KID-Based Light Detectors of CALDER

    Science.gov (United States)

    Casali, N.; Bellini, F.; Cardani, L.; Castellano, M. G.; Colantoni, I.; Coppolecchia, A.; Cosmelli, C.; Cruciani, A.; D'Addabbo, A.; Di Domizio, S.; Martinez, M.; Tomei, C.; Vignati, M.

    2016-07-01

    The aim of the Cryogenic wide-Area Light Detectors with Excellent Resolution (CALDER) project is the development of light detectors with active area of 5 × 5 cm2 and noise energy resolution smaller than 20 eV RMS, implementing phonon-mediated kinetic inductance detectors. The detectors are developed to improve the background suppression in large-mass bolometric experiments such as CUORE, via the double read-out of the light and the heat released by particles interacting in the bolometers. In this work, we present the characterization of the first light detectors developed by CALDER. We describe the analysis tools to evaluate the resonator parameters (resonant frequency and quality factors) taking into account simultaneously all the resonance distortions introduced by the read-out chain (as the feed-line impedance and its mismatch) and by the power stored in the resonator itself. We detail the method for the selection of the optimal point for the detector operation (maximizing the signal-to-noise ratio). Finally, we present the response of the detector to optical pulses in the energy range of 0{-}30 keV.

  5. Study of a nTHGEM-based thermal neutron detector

    Science.gov (United States)

    Li, Ke; Zhou, Jian-Rong; Wang, Xiao-Dong; Xiong, Tao; Zhang, Ying; Xie, Yu-Guang; Zhou, Liang; Xu, Hong; Yang, Gui-An; Wang, Yan-Feng; Wang, Yan; Wu, Jin-Jie; Sun, Zhi-Jia; Hu, Bi-Tao

    2016-07-01

    With new generation neutron sources, traditional neutron detectors cannot satisfy the demands of the applications, especially under high flux. Furthermore, facing the global crisis in 3He gas supply, research on new types of neutron detector as an alternative to 3He is a research hotspot in the field of particle detection. GEM (Gaseous Electron Multiplier) neutron detectors have high counting rate, good spatial and time resolution, and could be one future direction of the development of neutron detectors. In this paper, the physical process of neutron detection is simulated with Geant4 code, studying the relations between thermal conversion efficiency, boron thickness and number of boron layers. Due to the special characteristics of neutron detection, we have developed a novel type of special ceramic nTHGEM (neutron THick GEM) for neutron detection. The performance of the nTHGEM working in different Ar/CO2 mixtures is presented, including measurements of the gain and the count rate plateau using a copper target X-ray source. A detector with a single nTHGEM has been tested for 2-D imaging using a 252Cf neutron source. The key parameters of the performance of the nTHGEM detector have been obtained, providing necessary experimental data as a reference for further research on this detector. Supported by National Natural Science Foundation of China (11127508, 11175199, 11205253, 11405191), Key Laboratory of Neutron Physics, CAEP (2013DB06, 2013BB04) and CAS (YZ201512)

  6. Using GIS and Google Earth for the creation of the Going-to-the-Sun Road Avalanche Atlas, Glacier National Park, Montana, USA

    Science.gov (United States)

    Peitzsch, Erich H.; Fagre, Daniel B.; Dundas, Mark

    2010-01-01

    Snow avalanche paths are key geomorphologic features in Glacier National Park, Montana, and an important component of mountain ecosystems: they are isolated within a larger ecosystem, they are continuously disturbed, and they contain unique physical characteristics (Malanson and Butler, 1984). Avalanches impact subalpine forest structure and function, as well as overall biodiversity (Bebi et al., 2009). Because avalanches are dynamic phenomena, avalanche path geometry and spatial extent depend upon climatic regimes. The USGS/GNP Avalanche Program formally began in 2003 as an avalanche forecasting program for the spring opening of the ever-popular Going-to-the-Sun Road (GTSR), which crosses through 37 identified avalanche paths. Avalanche safety and forecasting is a necessary part of the GTSR spring opening procedures. An avalanche atlas detailing topographic parameters and oblique photographs was completed for the GTSR corridor in response to a request from GNP personnel for planning and resource management. Using ArcMap 9.2 GIS software, polygons were created for every avalanche path affecting the GTSR using aerial imagery, field-based observations, and GPS measurements of sub-meter accuracy. Spatial attributes for each path were derived within the GIS. Resulting products include an avalanche atlas book for operational use, a geoPDF of the atlas, and a Google Earth flyover illustrating each path and associated photographs. The avalanche atlas aids park management in worker safety, infrastructure planning, and natural resource protection by identifying avalanche path patterns and location. The atlas was created for operational and planning purposes and is also used as a foundation for research such as avalanche ecology projects and avalanche path runout modeling.

  7. Silicon photomultiplier based photon detector module as a detector of Cherenkov photons

    Science.gov (United States)

    Korpar, Samo; Chagani, Hassan; Dolenec, Rok; Križan, Peter; Pestotnik, Rok; Stanovnik, Aleš

    2010-11-01

    We have constructed and tested a module, consisting of 64 (= 8×8) Hamamatsu MPPC S10362-11-100P silicon photomultipliers, for position sensitive detection of Cherenkov photons. Suitable light concentrators were produced to increase the efficiency and to improve the signal to noise ratio. The results of our measurements indicate that the performance of such a Cherenkov counter with aerogel radiator could meet the requirements of particle identification at the foreseen upgraded Belle detector.

  8. Particle detectors based on InP Schottky diodes

    International Nuclear Information System (INIS)

    A study of electrical properties and detection performance of Indium Phosphide detector structures with Schottky contacts prepared on high purity p-type InP was performed. Schottky barrier detectors were prepared by vacuum evaporation of Pd on p-type epitaxial layers grown on Zn-doped p-type substrates. The detection performance of the detectors was characterized by the measurement of pulse-height spectra with alpha particles emitted from 241Am source at room temperature. The influence of the quality of p-type epitaxial layers on the charge-collection efficiency and energy resolution in the full-width half-maximum is discussed.

  9. Optimisation and Characterisation of Glass RPC for India-based Neutrino Observatory Detectors

    CERN Document Server

    Kanishka, R; Indumathi, D

    2016-01-01

    The proposed magnetised Iron CALorimeter detector (ICAL) to be built in the India-based Neutrino Observatory (INO) laboratory aims to detect atmospheric muon neutrinos. In order to achieve improved physics results, the constituent components of the detector must be fully understood by proper characterisation and optimisation of various parameters. Resistive Plate Chambers (RPCs) are the active detector elements in the ICAL detector and can be made of glass or bakelite. The number of RPCs required for this detector is very large number so a detailed R & D is necessary to establish the characterisation and optimisation of these RPCs. These detectors once installed will be taking data for 15-20 years. In this paper, we report the selection criteria of glass used of various Indian manufacturers such as Asahi, Saint Gobain and Modi. Based on the factors like aging that deteriorate the quality of glass the choice is made. The glass characterisation studies include UV-VIS transmission for optical properties, SEM...

  10. Multiple Detectors Based Analytical Performance of Spectrum Sensing

    Directory of Open Access Journals (Sweden)

    S.Taruna

    2014-03-01

    Full Text Available A key challenge in operating cognitive radios (CRs in a self-organizing (ad hoc network is how to adaptively and efficiently utilize spectrum resources keeping in mind that no interference is caused to primary users and also that no spectrum is rendered unused when a secondary user is waiting for access. Detecting the spectrum holes using one detector can be insufficient for increasing secondary users. In the proposed paper, an attempt has been made to implement multiple detectors to improve the probability of detection by increasing the SNR. Multiple detector technique has been implemented using various methods like Selection Combining (SC, Equal Gain Combining (EGC, and Maximum Ratio Combining (MRC, to discover which of these methods provide better increase in SNR as the numbers of detectors are increased.

  11. AlN Based Extreme Ultraviolet (EUV) Detectors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This Phase I project is to investigate the feasibility for achieving EUV detectors for space applications by exploiting the ultrahigh bandgap semiconductor - AlN....

  12. Calorimeter based detectors for high energy hadron colliders. [Progress report

    Energy Technology Data Exchange (ETDEWEB)

    1993-06-23

    The work was directed in two complementary directions, the D0 experiment at Fermilab, and the GEM detector for the SSC. Efforts have been towards the data taking and analysis with the newly commissioned D0 detector at Fermilab in the {bar p}p Collider run that started in May 1992 and ended on June 1, 1993. We involved running and calibration of the calorimeter and tracking chambers, the second level trigger development, and various parts of the data analysis, as well as studies for the D0 upgrade planned in the second half of this decade. Another major accomplishment was the ``delivery`` of the Technical Design Report for the GEM SSC detector. Efforts to the overall detector and magnet design, design of the facilities, installation studies, muon system coordination, muon chamber design and tests, muon system simulation studies, and physics simulation studies. In this document we describe these activities separately.

  13. Calorimeter based detectors for high energy hadron colliders

    Energy Technology Data Exchange (ETDEWEB)

    1993-06-23

    The work was directed in two complementary directions, the D0 experiment at Fermilab, and the GEM detector for the SSC. Efforts have been towards the data taking and analysis with the newly commissioned D0 detector at Fermilab in the [bar p]p Collider run that started in May 1992 and ended on June 1, 1993. We involved running and calibration of the calorimeter and tracking chambers, the second level trigger development, and various parts of the data analysis, as well as studies for the D0 upgrade planned in the second half of this decade. Another major accomplishment was the delivery'' of the Technical Design Report for the GEM SSC detector. Efforts to the overall detector and magnet design, design of the facilities, installation studies, muon system coordination, muon chamber design and tests, muon system simulation studies, and physics simulation studies. In this document we describe these activities separately.

  14. Injection quality measurements with diamond based particle detectors

    CERN Document Server

    Stein, Oliver; CERN. Geneva. ATS Department

    2016-01-01

    During the re-commissioning phase of the LHC after the long shutdown 1 very high beam losses were observed at the TDI during beam injection. The losses reached up to 90% of the dump threshold. To decrease the through beam losses induced stress on the accelerator components these loss levels need to be reduced. Measurements with diamond based particle detectors (dBLMs), which have nano-second time resolution, revealed that the majority of these losses come from recaptured SPS beam surrounding the nominal bunch train. In this MD the injection loss patterns and loss intensities were investigated in greater detail. Performed calibration shots on the TDI (internal beam absorber for injection) gave a conversion factor from impacting particles intensities to signal in the dBLMs (0.1Vs/109 protons). Using the SPS tune kicker for cleaning the recaptured beam in the SPS and changing the LHC injection kicker settings resulted in a reduction of the injection losses. For 144 bunch injections the loss levels were decreased...

  15. CdTe detector based PIXE mapping of geological samples

    Energy Technology Data Exchange (ETDEWEB)

    Chaves, P.C., E-mail: cchaves@ctn.ist.utl.pt [Centro de Física Atómica da Universidade de Lisboa, Av. Prof. Gama Pinto 2, 1649-003 Lisboa (Portugal); IST/ITN, Instituto Superior Técnico, Universidade Técnica de Lisboa, Campus Tecnológico e Nuclear, EN10, 2686-953 Sacavém (Portugal); Taborda, A. [Centro de Física Atómica da Universidade de Lisboa, Av. Prof. Gama Pinto 2, 1649-003 Lisboa (Portugal); IST/ITN, Instituto Superior Técnico, Universidade Técnica de Lisboa, Campus Tecnológico e Nuclear, EN10, 2686-953 Sacavém (Portugal); Oliveira, D.P.S. de [Laboratório Nacional de Energia e Geologia (LNEG), Apartado 7586, 2611-901 Alfragide (Portugal); Reis, M.A. [Centro de Física Atómica da Universidade de Lisboa, Av. Prof. Gama Pinto 2, 1649-003 Lisboa (Portugal); IST/ITN, Instituto Superior Técnico, Universidade Técnica de Lisboa, Campus Tecnológico e Nuclear, EN10, 2686-953 Sacavém (Portugal)

    2014-01-01

    A sample collected from a borehole drilled approximately 10 km ESE of Bragança, Trás-os-Montes, was analysed by standard and high energy PIXE at both CTN (previous ITN) PIXE setups. The sample is a fine-grained metapyroxenite grading to coarse-grained in the base with disseminated sulphides and fine veinlets of pyrrhotite and pyrite. Matrix composition was obtained at the standard PIXE setup using a 1.25 MeV H{sup +} beam at three different spots. Medium and high Z elemental concentrations were then determined using the DT2fit and DT2simul codes (Reis et al., 2008, 2013 [1,2]), on the spectra obtained in the High Resolution and High Energy (HRHE)-PIXE setup (Chaves et al., 2013 [3]) by irradiation of the sample with a 3.8 MeV proton beam provided by the CTN 3 MV Tandetron accelerator. In this paper we present results, discuss detection limits of the method and the added value of the use of the CdTe detector in this context.

  16. MEMS-based infrared detector for body thermometer

    Science.gov (United States)

    Yoo, Kum-Pyo; Kim, Yun-Ho; Min, Nam-Ki

    2005-12-01

    Infrared detectors have many application fields. One of those, MEMS based thermopile is attractive for many low-cost commercial and industrial applications, mainly because it does not require cooling for operation and the process technologies are relatively simple. The MEMS thermopile fabricated on a silicon nitride microbridge structure was proposed. Using microbridge rather conventional membrane makes it possible to fabricate much smaller micro thermopile and to reduce heat loss because of small contact area at silicon rim. The bridge material is only composed of Si3N4. The thermocouple was used a poly-Si and an aluminum. The characteristic of electromotive force (EMF) generation was evaluated for various patterns at hot junction. Aluminum thermocouple shape on bridge structure was designed two patterns. One was a square shape and the other shape was a hollow square. The output voltage of hollow square-type electrode was increased in compared with square-type electrode from 3.03uV/°C to 4.609uV/°C at body temperature (37°C). With the same membrane dimensions and the same overall thickness of the chip a thermopile on microbridge is almost 53% smaller a conventional thermopile chip.

  17. Development of Optimal Photosensors Based Heart Pulse Detector

    Directory of Open Access Journals (Sweden)

    N. M. Z. Hashim

    2013-08-01

    Full Text Available The development of heart pulse instruments rapidly fast in market since 21st century. However, the heart pulse detector is expensive due to the complicated system and it is used widely only in hospitals and clinics. The project is targeting to develop a significant photosensor to the medical fields that is easy to use and monitor their health by the user everywhere. The other target is to develop acomfortable instrument, reliable, accurate result to develop of heart pulse using low cost photosensors. This project involved both hardware and software with related to signal processing, mathematical,computational, formalisms, modeling techniques for transforming, transmitting and also for analog or digital signal. This project also used Peripheral Interface Controller (PIC 16F877A microcontroller asthe main function to control other elements. Result showed this project functioned smoothly and successfully with overall objectives were achieved. Apart from that, this project give good services forpeople to monitor their heart condition form time to time. In the future, wireless connection e.g. Global System for Mobile Communications (GSM and Zigbee would be developed to make the system more reliable to the current world. Furthermore, the system should be compatible to various environments such as Android based OS so that it can be controlled away from the original location.

  18. Avalanches in dry and saturated disordered media at fracture

    Science.gov (United States)

    Milanese, Enrico; Yılmaz, Okan; Molinari, Jean-François; Schrefler, Bernhard

    2016-04-01

    This paper analyzes fracturing in inhomogeneous media under dry and fully saturated conditions. We adopt a central force model with continuous damage to study avalanche behavior in a two-dimensional truss lattice undergoing dilation. Multiple fractures can develop at once and a power-law distribution of the avalanche size is observed. The values for the power-law exponent are compared with the ones found in the literature and scale-free behavior is suggested. The fracture evolves intermittently in time because only some avalanches correspond to fracture advancement. A fully saturated model with continuous damage based on the extended Biot's theory is developed and avalanche behavior is studied in the presence of fluid, varying the fluid boundary conditions. We show that power-law behavior is destroyed when the fluid flux governs the problem. Fluid pressure behavior during intermittent crack tip advancement is studied for the continuous-damage fully saturated model. It is found that when mechanical loading prevails, the pressure rises when the crack advances, while when fluid loading prevails, the pressure drops when the crack advances.

  19. Avalanches in dry and saturated disordered media at fracture.

    Science.gov (United States)

    Milanese, Enrico; Yılmaz, Okan; Molinari, Jean-François; Schrefler, Bernhard

    2016-04-01

    This paper analyzes fracturing in inhomogeneous media under dry and fully saturated conditions. We adopt a central force model with continuous damage to study avalanche behavior in a two-dimensional truss lattice undergoing dilation. Multiple fractures can develop at once and a power-law distribution of the avalanche size is observed. The values for the power-law exponent are compared with the ones found in the literature and scale-free behavior is suggested. The fracture evolves intermittently in time because only some avalanches correspond to fracture advancement. A fully saturated model with continuous damage based on the extended Biot's theory is developed and avalanche behavior is studied in the presence of fluid, varying the fluid boundary conditions. We show that power-law behavior is destroyed when the fluid flux governs the problem. Fluid pressure behavior during intermittent crack tip advancement is studied for the continuous-damage fully saturated model. It is found that when mechanical loading prevails, the pressure rises when the crack advances, while when fluid loading prevails, the pressure drops when the crack advances. PMID:27176380

  20. Airplane Ice Detector Based on a Microwave Transmission Line

    Science.gov (United States)

    Ngo, Phong; Arndt, G. Dickey; Carl, James R.

    2004-01-01

    An electronic instrument that could detect the potentially dangerous buildup of ice on an airplane wing is undergoing development. The instrument is based on a microwave transmission line configured as a capacitance probe: at selected spots, the transmission-line conductors are partly exposed to allow any ice and/or liquid water present at those spots to act as predominantly capacitive electrical loads on the transmission line. These loads change the input impedance of the transmission line, as measured at a suitable excitation frequency. Thus, it should be possible to infer the presence of ice and/or liquid water from measurements of the input impedance and/or electrical parameters related to the input impedance. The sensory transmission line is of the microstrip type and thus thin enough to be placed on an airplane wing without unduly disturbing airflow in flight. The sensory spots are small areas from which the upper layer of the microstrip has been removed to allow any liquid water or ice on the surface to reach the transmission line. The sensory spots are spaced at nominal open-circuit points, which are at intervals of a half wavelength (in the transmission line, not in air) at the excitation frequency. The excitation frequency used in the experiments has been 1 GHz, for which a half wavelength in the transmission line is .4 in. (.10 cm). The figure depicts a laboratory prototype of the instrument. The impedance-related quantities chosen for use in this version of the instrument are the magnitude and phase of the scattering parameter S11 as manifested in the in-phase (I ) and quadrature (Q) outputs of the phase detector. By careful layout of the transmission line (including the half-wavelength sensor spacing), one can ensure that the amplitude and phase of the input to the phase detector keep shifting in the same direction as ice forms on one or more of the sensor areas. Although only one transmission-line sensor strip is used in the laboratory version, in a

  1. Ultracold neutron detectors based on 10B converters used in the qBounce experiments ☆

    OpenAIRE

    Jenke, Tobias; Cronenberg, Gunther; Filter, Hanno; Geltenbort, Peter; Klein, Martin; Lauer, Thorsten; Mitsch, Kevin; Saul, Heiko; Seiler, Dominik; Stadler, David; Thalhammer, Martin; Abele, Hartmut

    2013-01-01

    Gravity experiments with very slow, so-called ultracold neutrons connect quantum mechanics with tests of Newton's inverse square law at short distances. These experiments face a low count rate and hence need highly optimized detector concepts. In the frame of this paper, we present low-background ultracold neutron counters and track detectors with micron resolution based on a 10B converter. We discuss the optimization of 10B converter layers, detector design and concepts for read-out electron...

  2. BJT detector with FPGA-based read-out for alpha particle monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Tyzhnevyi, V; Dalla Betta, G-F [Universita di Trento, via Sommarive, 14, 38123 Trento (Italy); Rovati, L [Universita di Modena e Reggio Emilia, via Vignolese 905, 41125 Modena (Italy); Verzellesi, G [Universita di Modena e Reggio Emilia, via Amendola 2, Pad. Morselli, 42100 Reggio Emilia (Italy); Zorzi, N, E-mail: tyzhnevyi@disi.unitn.it [Fondazione Bruno Kessler, via Sommarive, 18, 38123 Trento (Italy)

    2011-01-15

    In this work we introduce a new prototype of readout electronics (ALPHADET), which was designed for an {alpha}-particle detection system based on a bipolar junction transistor (BJT) detector. The system uses an FPGA, which provides many advantages at the stage of prototyping and testing the detector. The main design and electrical features of the board are discussed in this paper, along with selected results from the characterization of ALPHADET coupled to BJT detectors.

  3. Spatial resolution of a {\\mu}PIC-based neutron imaging detector

    OpenAIRE

    Parker, Joseph D.; Harada, Masahide; Hattori, Kaori; Iwaki, Satoru; Kabuki, Shigeto; Kishimoto, Yuji; Kubo, Hidetoshi; Kurosawa, Shunsuke; Matsuoka, Yoshihiro; Miuchi, Kentaro; Mizumoto, Tetsuya; Nishimura, Hironobu; Oku, Takayuki; Sawano, Tatsuya; Shinohara, Takenao

    2013-01-01

    We present a detailed study of the spatial resolution of our time-resolved neutron imaging detector utilizing a new neutron position reconstruction method that improves both spatial resolution and event reconstruction efficiency. Our prototype detector system, employing a micro-pattern gaseous detector known as the micro-pixel chamber ({\\mu}PIC) coupled with a field-programmable-gate-array-based data acquisition system, combines 100{\\mu}m-level spatial and sub-{\\mu}s time resolutions with exc...

  4. Theoretical performance analysis for CMOS based high resolution detectors.

    Science.gov (United States)

    Jain, Amit; Bednarek, Daniel R; Rudin, Stephen

    2013-03-01

    High resolution imaging capabilities are essential for accurately guiding successful endovascular interventional procedures. Present x-ray imaging detectors are not always adequate due to their inherent limitations. The newly-developed high-resolution micro-angiographic fluoroscope (MAF-CCD) detector has demonstrated excellent clinical image quality; however, further improvement in performance and physical design may be possible using CMOS sensors. We have thus calculated the theoretical performance of two proposed CMOS detectors which may be used as a successor to the MAF. The proposed detectors have a 300 μm thick HL-type CsI phosphor, a 50 μm-pixel CMOS sensor with and without a variable gain light image intensifier (LII), and are designated MAF-CMOS-LII and MAF-CMOS, respectively. For the performance evaluation, linear cascade modeling was used. The detector imaging chains were divided into individual stages characterized by one of the basic processes (quantum gain, binomial selection, stochastic and deterministic blurring, additive noise). Ranges of readout noise and exposure were used to calculate the detectors' MTF and DQE. The MAF-CMOS showed slightly better MTF than the MAF-CMOS-LII, but the MAF-CMOS-LII showed far better DQE, especially for lower exposures. The proposed detectors can have improved MTF and DQE compared with the present high resolution MAF detector. The performance of the MAF-CMOS is excellent for the angiography exposure range; however it is limited at fluoroscopic levels due to additive instrumentation noise. The MAF-CMOS-LII, having the advantage of the variable LII gain, can overcome the noise limitation and hence may perform exceptionally for the full range of required exposures; however, it is more complex and hence more expensive. PMID:24353390

  5. Characterization of the KID-Based Light Detectors of CALDER

    CERN Document Server

    Casali, N; Cardani, L; Castellano, M G; Colantoni, I; Coppolecchia, A; Cosmelli, C; Cruciani, A; D'Addabbo, A; Di Dominio, S; Martinez, M; Tomei, C; Vignati, M

    2015-01-01

    The aim of the Cryogenic wide-Area Light Detectors with Excellent Resolution (CALDER) project is the development of light detectors with active area of $5\\times5$ cm$^2$ and noise energy resolution smaller than 20 eV RMS, implementing phonon-mediated kinetic inductance detectors. The detectors are developed to improve the background suppression in large-mass bolometric experiments such as CUORE, via the double read-out of the light and the heat released by particles interacting in the bolometers. In this work, we present the characterization of the first light detectors developed by CALDER. We describe the analysis tools to evaluate the resonator parameters (resonant frequency and quality factors) taking into account simultaneously all the resonance distortions introduced by the read-out chain (as the feed-line impedance and its mismatch) and by the power stored in the resonator itself. We detail the method for the selection of the optimal point for the detector operation (maximizing the signal-to-noise ratio...

  6. Silicon Geiger mode avalanche photodiodes

    Institute of Scientific and Technical Information of China (English)

    M. Mazzillo; S. Billotta; G. Bonanno; A. Campisi; L. Cosentino; P. Finocchiaro; F. Musumeci; S.Privitera; S. Tudisco; G. Condorelli; D. Sanfilippo; G. Fallica; E. Sciacca; S. Aurite; S. Lombardo; E. Rlmini; M. Belluso

    2007-01-01

    In this letter we present the results regarding the electrical and optical characterization of Geiger mode silicon avalanche photodiodes (GMAP) fabricated by silicon standard planar technology. Low dark count rates, negligible afterpulsing effects,good timing resolution and high quantum detection efficiency in all the visible range have been measured. The very good electro-optical performances of our photodiodes make them attractive for the fabrication of arrays with a large number of GMAP to be used both in the commercial and the scientific fields, as telecommunications and nuclear medical imaging.

  7. Single Photon Counting UV Solar-Blind Detectors Using Silicon and III-Nitride Materials.

    Science.gov (United States)

    Nikzad, Shouleh; Hoenk, Michael; Jewell, April D; Hennessy, John J; Carver, Alexander G; Jones, Todd J; Goodsall, Timothy M; Hamden, Erika T; Suvarna, Puneet; Bulmer, J; Shahedipour-Sandvik, F; Charbon, Edoardo; Padmanabhan, Preethi; Hancock, Bruce; Bell, L Douglas

    2016-01-01

    Ultraviolet (UV) studies in astronomy, cosmology, planetary studies, biological and medical applications often require precision detection of faint objects and in many cases require photon-counting detection. We present an overview of two approaches for achieving photon counting in the UV. The first approach involves UV enhancement of photon-counting silicon detectors, including electron multiplying charge-coupled devices and avalanche photodiodes. The approach used here employs molecular beam epitaxy for delta doping and superlattice doping for surface passivation and high UV quantum efficiency. Additional UV enhancements include antireflection (AR) and solar-blind UV bandpass coatings prepared by atomic layer deposition. Quantum efficiency (QE) measurements show QE > 50% in the 100-300 nm range for detectors with simple AR coatings, and QE ≅ 80% at ~206 nm has been shown when more complex AR coatings are used. The second approach is based on avalanche photodiodes in III-nitride materials with high QE and intrinsic solar blindness. PMID:27338399

  8. Single Photon Counting UV Solar-Blind Detectors Using Silicon and III-Nitride Materials.

    Science.gov (United States)

    Nikzad, Shouleh; Hoenk, Michael; Jewell, April D; Hennessy, John J; Carver, Alexander G; Jones, Todd J; Goodsall, Timothy M; Hamden, Erika T; Suvarna, Puneet; Bulmer, J; Shahedipour-Sandvik, F; Charbon, Edoardo; Padmanabhan, Preethi; Hancock, Bruce; Bell, L Douglas

    2016-06-21

    Ultraviolet (UV) studies in astronomy, cosmology, planetary studies, biological and medical applications often require precision detection of faint objects and in many cases require photon-counting detection. We present an overview of two approaches for achieving photon counting in the UV. The first approach involves UV enhancement of photon-counting silicon detectors, including electron multiplying charge-coupled devices and avalanche photodiodes. The approach used here employs molecular beam epitaxy for delta doping and superlattice doping for surface passivation and high UV quantum efficiency. Additional UV enhancements include antireflection (AR) and solar-blind UV bandpass coatings prepared by atomic layer deposition. Quantum efficiency (QE) measurements show QE > 50% in the 100-300 nm range for detectors with simple AR coatings, and QE ≅ 80% at ~206 nm has been shown when more complex AR coatings are used. The second approach is based on avalanche photodiodes in III-nitride materials with high QE and intrinsic solar blindness.

  9. Single Photon Counting UV Solar-Blind Detectors Using Silicon and III-Nitride Materials

    Science.gov (United States)

    Nikzad, Shouleh; Hoenk, Michael; Jewell, April D.; Hennessy, John J.; Carver, Alexander G.; Jones, Todd J.; Goodsall, Timothy M.; Hamden, Erika T.; Suvarna, Puneet; Bulmer, J.; Shahedipour-Sandvik, F.; Charbon, Edoardo; Padmanabhan, Preethi; Hancock, Bruce; Bell, L. Douglas

    2016-01-01

    Ultraviolet (UV) studies in astronomy, cosmology, planetary studies, biological and medical applications often require precision detection of faint objects and in many cases require photon-counting detection. We present an overview of two approaches for achieving photon counting in the UV. The first approach involves UV enhancement of photon-counting silicon detectors, including electron multiplying charge-coupled devices and avalanche photodiodes. The approach used here employs molecular beam epitaxy for delta doping and superlattice doping for surface passivation and high UV quantum efficiency. Additional UV enhancements include antireflection (AR) and solar-blind UV bandpass coatings prepared by atomic layer deposition. Quantum efficiency (QE) measurements show QE > 50% in the 100–300 nm range for detectors with simple AR coatings, and QE ≅ 80% at ~206 nm has been shown when more complex AR coatings are used. The second approach is based on avalanche photodiodes in III-nitride materials with high QE and intrinsic solar blindness. PMID:27338399

  10. Dendrogeomorphology and high-magnitude snow avalanches: a review and case study

    Directory of Open Access Journals (Sweden)

    D. R. Butler

    2008-04-01

    Full Text Available The application of the principles of dendrogeomorphology for the dating of high-magnitude snow avalanches is well established in the natural hazards literature. A variety of methodologies are employed by different authors, however, and no standardization currently exists for appropriate sample sizes, the issue of "weighting" certain tree-ring responses as more important than others, or the minimum number of responding trees required in order to infer an avalanche event. We review the literature of dendrogeomorphology as it applies to snow avalanches, and examine the questions of sample size, type of ring reactions dated and weighted, and minimum responses. We present tree-ring data from two avalanche paths in the Rocky Mountains of Montana, USA, from trees uprooted by major snow avalanches in the winter of 2002. These data provide distinct chronologies of past avalanche events, and also illustrate how the critical choice of a minimum Index Number can affect the number of avalanche events in a final chronology based on tree-ring analysis.

  11. SiC-based Photo-detectors for UV, VUV, EUV and Soft X-ray Detection

    Science.gov (United States)

    Yan, Feng

    2006-01-01

    A viewgraph presentation describing an ideal Silicon Carbide detector for ultraviolet, vacuum ultraviolet, extreme ultraviolet and soft x-ray detection is shown. The topics include: 1) An ideal photo-detector; 2) Dark current density of SiC photodiodes at room temperature; 3) Dark current in SiC detectors; 4) Resistive and capacitive feedback trans-impedance amplifier; 5) Avalanche gain; 6) Excess noise; 7) SNR in single photon counting mode; 8) Structure of SiC single photon counting APD and testing structure; 9) Single photon counting waveform and testing circuit; 10) Amplitude of SiC single photon counter; 11) Dark count of SiC APD photon counters; 12) Temperature-dependence of dark count rate; 13) Reduce the dark count rate by reducing the breakdown electric field; 14) Spectrum range for SiC detectors; 15) QE curves of Pt/4H-SiC photodiodes; 16) QE curve of SiC; 17) QE curves of SiC photodiode vs. penetration depth; 18) Visible rejection of SiC photodiodes; 19) Advantages of SiC photodiodes; 20) Competitors of SiC detectors; 21) Extraterrestrial solar spectra; 22) Visible-blind EUV detection; 23) Terrestrial solar spectra; and 24) Less than 1KeV soft x-ray detection.

  12. Review of amorphous silicon based particle detectors: the quest for single particle detection

    Science.gov (United States)

    Wyrsch, N.; Ballif, C.

    2016-10-01

    Hydrogenated amorphous silicon (a-Si:H) is attractive for radiation detectors because of its radiation resistance and processability over large areas with mature Si microfabrication techniques. While the use of a-Si:H for medical imaging has been very successful, the development of detectors for particle tracking and minimum-ionizing-particle detection has lagged, with almost no practical implementation. This paper reviews the development of various types of a-Si:H-based detectors and discusses their respective achievements and limitations. It also presents more recent developments of detectors that could potentially achieve single particle detection and be integrated in a monolithic fashion into a variety of applications.

  13. 2-dimensional GEM detector with FEE based on the nXYTER ASIC

    International Nuclear Information System (INIS)

    The GEM detector with 2-dimensional readout printed circuit board and an active area 10 × 10 cm2 for detection of diffraction patterns has been developed and constructed. A multichannel front end electronics based on two 128 channel nXYTER chips has been used. The investigations with this detector were made with high rate X-ray sources (6–15 keV). The measurement results of gas gain, spatial resolution and energy resolution are presented. The application of the GEM detector as a potential detector for material science and other diffraction experiments is presented

  14. Development of wide-ranged diamond-based detector unit for gamma radiation measurement

    Science.gov (United States)

    Baranova, M. A.; Boyko, A. V.; Chebyshev, S. B.; Cherkashin, I. I.; Kireev, V. P.; Petrov, V. I.

    2016-02-01

    In the article the description of wide-ranged diamond-based detector unit is given. Characteristics of the diamond detector were studied in current and in impulse mode. As well it was studied how detector's sensitivity depends on power doze within the limits from 10-3 to 0,4Gy/h (impulse mode) and from 10-1to 2 104Gy/h (current mode). On the basis of the obtained data it is possible to estimate about the possibility of using the detector to prevent emergency accident on a nuclear power plant and for everyday control at a nuclear power plant.

  15. Physics Potential of the ICAL detector at the India-based Neutrino Observatory (INO)

    CERN Document Server

    Ahmed, Shakeel; Hasan, Rashid; Salim, Mohammad; Singh, S K; Inbanathan, S S R; Singh, Venktesh; Subrahmanyam, V S; Behera, Shiba Prasad; Chandratre, Vinay B; Dash, Nitali; Datar, Vivek M; Kashyap, V K S; Mohanty, Ajit K; Pant, Lalit M; Chatterjee, Animesh; Choubey, Sandhya; Gandhi, Raj; Ghosh, Anushree; Tiwari, Deepak; Ajmi, Ali; Sankar, S Uma; Behera, Prafulla; Chacko, Aleena; Jafer, Sadiq; Libby, James; Raveendrababu, K; Rebin, K R; Indumathi, D; Meghna, K; Lakshmi, S M; Murthy, M V N; Pal, Sumanta; Rajasekaran, G; Sinha, Nita; Agarwalla, Sanjib Kumar; Khatun, Amina; Mehta, Poonam; Bhatnagar, Vipin; Kanishka, R; Kumar, A; Shahi, J S; Singh, J B; Ghosh, Monojit; Ghoshal, Pomita; Goswami, Srubabati; Gupta, Chandan; Raut, Sushant; Bhattacharya, Sudeb; Bose, Suvendu; Ghosal, Ambar; Jash, Abhik; Kar, Kamalesh; Majumdar, Debasish; Majumdar, Nayana; Mukhopadhyay, Supratik; Saha, Satyajit; Acharya, B S; Banerjee, Sudeshna; Bhattacharya, Kolahal; Dasgupta, Sudeshna; Devi, Moon Moon; Dighe, Amol; Majumder, Gobinda; Mondal, Naba K; Redij, Asmita; Samuel, Deepak; Satyanarayana, B; Thakore, Tarak; Ravikumar, C D; Vinodkumar, A M; Gangopadhyay, Gautam; Raychaudhuri, Amitava; Choudhary, Brajesh C; Gaur, Ankit; Kaur, Daljeet; Kumar, Ashok; Kumar, Sanjeev; Naimuddin, Md; Bari, Waseem; Malik, Manzoor A; Singh, Jyotsna; Krishnaveni, S; Ravikumar, H B; Ranganathaiah, C; Mahapatra, Swapna; Biswas, Saikat; Chattopadhyay, Subhasis; Ganai, Rajesh; Ghosh, Tapasi; Viyogi, Y P

    2015-01-01

    The upcoming 50 kt magnetized iron calorimeter (ICAL) detector at the India-based Neutrino Observatory (INO) is designed to study the atmospheric neutrinos and antineutrinos separately over a wide range of energies and path lengths. The primary focus of this experiment is to explore the Earth matter effects by observing the energy and zenith angle dependence of the atmospheric neutrinos in the multi-GeV range. This study will be crucial to address some of the outstanding issues in neutrino oscillation physics, including the fundamental issue of neutrino mass hierarchy. In this document, we present the physics potential of the detector as obtained from realistic detector simulations. We describe the simulation framework, the neutrino interactions in the detector, and the expected response of the detector to particles traversing it. The ICAL detector can determine the energy and direction of the muons to a high precision, and in addition, its sensitivity to multi-GeV hadrons increases its physics reach substant...

  16. A measurement method of a detector response function for monochromatic electrons based on the Compton scattering

    Science.gov (United States)

    Bakhlanov, S. V.; Bazlov, N. V.; Derbin, A. V.; Drachnev, I. S.; Kayunov, A. S.; Muratova, V. N.; Semenov, D. A.; Unzhakov, E. V.

    2016-06-01

    In this paper we present a method of scintillation detector energy calibration using the gamma-rays. The technique is based on the Compton scattering of gamma-rays in a scintillation detector and subsequent photoelectric absorption of the scattered photon in the Ge-detector. The novelty of this method is that the source of gamma rays, the germanium and scintillation detectors are immediately arranged adjacent to each other. The method presents an effective solution for the detectors consisting of a low atomic number materials, when the ratio between Compton effect and photoelectric absorption is large and the mean path of gamma-rays is comparable to the size of the detector. The technique can be used for the precision measurements of the scintillator light yield dependence on the electron energy.

  17. A measurement method of a detector response function for monochromatic electrons based on the Compton scattering

    CERN Document Server

    Bakhlanov, S V; Derbin, A V; Drachnev, I S; Kayunov, A S; Muratova, V N; Semenov, D A; Unzhakov, E V

    2016-01-01

    In this paper we present a method of scintillation detector energy calibration using the gamma-rays. The technique is based on the Compton scattering of gamma-rays in a scintillation detector and subsequent photoelectric absorption of the scattered photon in the Ge-detector. The novelty of this method is that the source of gamma rays, the germanium and scintillation detectors are immediately arranged adjacent to each other. The method presents an effective solution for the detectors consisting of a low atomic number materials, when the ratio between Compton effect and photoelectric absorption is large and the mean path of gamma-rays is comparable to the size of the detector. The technique can be used for the precision measurements of the scintillator light yield dependence on the electron energy.

  18. Design and construct of a new detector for gas chromatography based on continuous negative corona discharge.

    Science.gov (United States)

    Ghahfarokhi, M Sharifian; Khayamian, T

    2011-05-01

    In this work, a new detector was designed and constructed based on negative corona discharge. This detector can be used separately or as a detector in gas chromatography. The detector and chromatographic variables including cell temperature, gas flow rates, voltage between the two electrodes, and column temperature were optimized. Chloroform was used as a test compound to evaluate the performance of the detector. The detection limit of chloroform was obtained 0.78 ng∕ml and its dynamic range was over the range of 2-840 ng∕ml. The relative standard detection was about 6% for the limit of quantification. This detector is able to be used as an alternative for analysis of compounds containing electronegative elements. PMID:21639545

  19. Detectors for proton counting. Si-APD and scintillation detectors

    International Nuclear Information System (INIS)

    Increased intensity of synchrotron radiation requests users to prepare photon pulse detectors having higher counting rates. As detectors for photon counting, silicon-avalanche photodiode (Si-APD) and scintillation detectors were chosen for the fifth series of detectors. Principle of photon detection by pulse and need of amplification function of the detector were described. Structure and working principle, high counting rate measurement system, bunch of electrons vs. counting rate, application example of NMR time spectroscopy measurement and comments for users were described for the Si-APD detector. Structure of scintillator and photomultiplier tube, characteristics of scintillator and performance of detector were shown for the NaI detector. Future development of photon pulse detectors was discussed. (T. Tanaka)

  20. Overspill avalanching in a dense reservoir network

    CERN Document Server

    Mamede, G L; Schneider, C M; de Araújo, J C; Herrmann, H J

    2012-01-01

    Sustainability of communities, agriculture, and industry is strongly dependent on an effective storage and supply of water resources. In some regions the economic growth has led to a level of water demand which can only be accomplished through efficient reservoir networks. Such infrastructures are not always planned at larger scale but rather made by farmers according to their local needs of irrigation during droughts. Based on extensive data from the upper Jaguaribe basin, one of the world's largest system of reservoirs, located in the Brazilian semiarid northeast, we reveal that surprisingly it self-organizes into a scale-free network exhibiting also a power-law in the distribution of the lakes and avalanches of discharges. With a new self-organized-criticality-type model we manage to explain the novel critical exponents. Implementing a flow model we are able to reproduce the measured overspill evolution providing a tool for catastrophe mitigation and future planning.

  1. Smaller, Lower-Power Fast-Neutron Scintillation Detectors

    Science.gov (United States)

    Patel, Jagdish; Blaes, Brent

    2008-01-01

    Scintillation-based fast-neutron detectors that are smaller and less power-hungry than mainstream scintillation-based fast-neutron detectors are undergoing development. There are numerous applications for such detectors in monitoring fast-neutron fluxes from nuclear reactors, nuclear materials, and natural sources, both on Earth and in outer space. A particularly important terrestrial application for small, low-power, portable fast-neutron detectors lies in the requirement to scan for nuclear materials in cargo and baggage arriving at international transportation facilities. The present development of miniature, low-power scintillation-based fast-neutron detectors exploits recent advances in the fabrication of avalanche photodiodes (APDs). Basically, such a detector includes a plastic scintillator, typically between 300 and 400 m thick with very thin silver mirror coating on all its faces except the one bonded to an APD. All photons generated from scintillation are thus internally reflected and eventually directed to the APD. This design affords not only compactness but also tight optical coupling for utilization of a relatively large proportion of the scintillation light. The combination of this tight coupling and the avalanche-multiplication gain (typically between 750 and 1,000) of the APD is expected to have enough sensitivity to enable monitoring of a fast-neutron flux as small as 1,000 cm(exp -2)s(exp -1). Moreover, pulse-height analysis can be expected to provide information on the kinetic energies of incident neutrons. It has been estimated that a complete, fully developed fast-neutron detector of this type, would be characterized by linear dimensions of the order of 10 cm or less, a mass of no more than about 0.5 kg, and a power demand of no more than a few watts.

  2. Semiconductor neutron detectors based on new types of materials

    International Nuclear Information System (INIS)

    Neutron detection in hostile environments such as nuclear reactors has been performed using a new kind of semiconductor detector. So far, crystalline semiconductor detectors are not used in nuclear reactor instrumentation because of their sensitivity to radiation damage. For doses in excess of a few tens of kilo rads, radiation induced lattice defects produce a strong loss in the standard semiconductor detector performances. In the last few years, new semiconductor materials having amorphous or polycrystalline structures such as silicon, silicon carbide or CVD diamond, became available. These semiconductors, produced by Chemical Vapor Deposition, come in the form of thin layers being typically a few tens of micron thick. Their crystalline structure is particularly resistant to radiation damage up to a few Mrads but prevent the material use in spectrometry measurements. Nevertheless, these detectors, working in a counting mode, are suitable for the detection of alpha particles produced by the neutron capture reaction with boron. Such thin film detectors have a very poor sensitivity to γ-ray background. Furthermore, they are easier and cheaper to implement than current neutron gas counters. Preliminary results obtained with diamond and amorphous silicon diodes exposed to α particles are presented. (authors). 7 figs., 3 tabs., 11 refs

  3. Development of a microstrip-based neutron detector

    Indian Academy of Sciences (India)

    S S Desai; A M Shaikh; V Radhakrishna; K Rajanna

    2004-08-01

    A gas-filled microstrip detector for thermal neutrons has been built and successfully tested in our laboratory. The detector has an active area of 20 mm × 15 mm and consists of alternate anodes and cathodes of widths 12 m and 300 m respectively. The anode to cathode gap is 150 m and the pitch is 612 m. A high resistance, meandering type horizontal strip connects the anodes at one end and aids in position sensing by charge division method. The detector is tested with gas mixtures 3He+Kr (1 : 2) and 3He+CF4 (2 : 1) at pressure of 3 atmospheres and using a Pu-Be neutron source. The pulse height spectrum shows energy resolution of ∼ 8% (FWHM) for the 764 keV peak at anode voltage of 525 V for 3He+Kr and ∼ 15% at anode voltage of 800 V for 3He+CF4. Gas gains up to 6.3 × 103 and 3.6 × 103 are obtained respectively with these gas mixtures. The overall efficiency of the detector along the sensitive length is tested by exposing the active area to neutrons and recording the position spectrum. The detector shows fairly uniform efficiency (∼ 45\\%) over the active length.

  4. Organic semiconductor nickel phthalocyanine-based photocapacitive and photoresistive detector

    Science.gov (United States)

    Shah, Mutabar; Karimov, Kh S.; Sayyad, M. H.

    2010-07-01

    In this study, the photosensitive organic semiconductor nickel phthalocyanine (NiPc) is investigated as a photocapacitive and photoresistive detector. NiPc thin film is grown by vacuum thermal evaporation on an indium tin oxide (ITO)-coated glass substrate. Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is deposited as a top electrode by drop-casting to fabricate the ITO/NiPc/PEDOT:PSS light detector. It has been observed that under the unmodulated filament lamp illumination of up to 9720 lux the capacitance of the detectors increased up to 21, 18 and 4% at a frequency of measuring voltage of 120 Hz, 1 kHz and 10 kHz, respectively, under dark conditions. The change in resistance with the variation in the intensity of light is also investigated. The capacitance and resistance of the light detector decrease with an increase in the frequency. It is assumed that the photocapacitive and photoresistive response of the detector is associated with polarization occurring due to the transfer of photo-generated electrons and holes. The calculated results are in reasonable agreement with the experimental results.

  5. Position resolution of a double junction superconductive detector based on a single material

    Science.gov (United States)

    Samedov, V. V.

    2008-02-01

    The Naples group from Istituto Nazionale di Fisica Nucleare presented the results of theoretical investigations of a new class of superconductive radiation detectors - double junction superconductive detector based on a single material [1]. In such detectors, the absorption of energy occurs in a long superconductive strip while two superconductive tunnel junctions positioned at the ends of the strip provide the readout of the signals. The main peculiarity of this type of detectors is that they are based on a single superconducting material, i.e., without trapping layers at the ends of the strip. In this paper, general approach to the position resolution of this type of detectors has been attempted. The formula for the position resolution is derived. It is shown that the application of the aluminium for the absorber may be the best possible way not only due to the small gap energy, but also mainly for STJ fabrication technology based on the aluminium oxide tunnel barrier.

  6. Asymmetric devices based on carbon nanotubes as detectors of sub-THz radiation

    Science.gov (United States)

    Gayduchenko, I. A.; Fedorov, G. E.; Stepanova, T. S.; Titova, N.; Voronov, B. M.; But, D.; Coquillat, D.; Diakonova, N.; Knap, W.; Goltsman, G. N.

    2016-08-01

    Demand for efficient terahertz (THz) radiation detectors resulted in intensive study of the asymmetric carbon nanostructures as a possible solution for that problem. In this work, we systematically investigate the response of asymmetric carbon nanodevices to sub-terahertz radiation using different sensing elements: from dense carbon nanotube (CNT) network to individual CNT. We conclude that the detectors based on individual CNTs both semiconducting and quasi-metallic demonstrate much stronger response in sub-THz region than detectors based on disordered CNT networks at room temperature. We also demonstrate the possibility of using asymmetric detectors based on CNT for imaging in the THz range at room temperature. Further optimization of the device configuration may result in appearance of novel terahertz radiation detectors.

  7. Plasmonic field confinement for separate absorption-multiplication in InGaAs nanopillar avalanche photodiodes

    Science.gov (United States)

    Farrell, Alan C.; Senanayake, Pradeep; Hung, Chung-Hong; El-Howayek, Georges; Rajagopal, Abhejit; Currie, Marc; Hayat, Majeed M.; Huffaker, Diana L.

    2015-12-01

    Avalanche photodiodes (APDs) are essential components in quantum key distribution systems and active imaging systems requiring both ultrafast response time to measure photon time of flight and high gain to detect low photon flux. The internal gain of an APD can improve system signal-to-noise ratio (SNR). Excess noise is typically kept low through the selection of material with intrinsically low excess noise, using separate-absorption-multiplication (SAM) heterostructures, or taking advantage of the dead-space effect using thin multiplication regions. In this work we demonstrate the first measurement of excess noise and gain-bandwidth product in III-V nanopillars exhibiting substantially lower excess noise factors compared to bulk and gain-bandwidth products greater than 200 GHz. The nanopillar optical antenna avalanche detector (NOAAD) architecture is utilized for spatially separating the absorption region from the avalanche region via the NOA resulting in single carrier injection without the use of a traditional SAM heterostructure.

  8. Fast neutron fields imaging with a CCD-based luminescent detector

    International Nuclear Information System (INIS)

    The paper considers some questions concerned with the development of an imaging system based on a CCD-detector for visualising fast neutron fields. From those the most important are: development of fast neutron screens, detector resistance to irradiation fields, and feasibility of fast neutron radiography and tomography at various neutron sources

  9. Fast neutron fields imaging with a CCD-based luminescent detector

    CERN Document Server

    Mikerov, V

    1999-01-01

    The paper considers some questions concerned with the development of an imaging system based on a CCD-detector for visualising fast neutron fields. From those the most important are: development of fast neutron screens, detector resistance to irradiation fields, and feasibility of fast neutron radiography and tomography at various neutron sources.

  10. Development and analysis of silicon based detectors for low energy nuclear radiation

    International Nuclear Information System (INIS)

    The design and assembly of a prototype silicon based detector especially for the detection of auroral X-rays is presented. The theoretical fundamentals are shown and the adoption of the detector for applications in future satellite experiments are described. 136 refs

  11. An Ultra-Wideband Schottky Diode Based Envelope Detector for 2.5 Gbps signals

    DEFF Research Database (Denmark)

    Cimoli, Bruno; Valdecasa, Guillermo Silva; Granja, Angel Blanco;

    2016-01-01

    In this paper an ultra-wideband (UWB) Schottky diode based envelope detector is reported. The detector consists of an input matching network, a Schottky diode and wideband output filtering network. The output network is tailored to demodulate ultra-wideband amplitude shift keying (ASK) signals up...

  12. An Omnidirectional Polarization Detector Based on a Metamaterial Absorber

    Science.gov (United States)

    Zhang, Binzhen; Zhang, Yong; Duan, Junping; Zhang, Wendong; Wang, Wanjun

    2016-01-01

    The theory, design, simulation, fabrication, and performance of an omnidirectional polarization detector (PD) with two resonances located in the X and Ka ranges based on a metamaterial absorber (MMA) are presented in this paper. The sandwich structure of PD is composed of 0.1 μm periodic “I” shaped patches on the metasurface, a dielectric of 200 μm FR-4 on the interlayer, and a 0.3 μm copper film on the substrate. PD absorptivity is first used to reflect and describe the polarization of the incident wave. The numerical results, derived from the standard full wave finite integration technology (FIT) of CST 2015, indicates that the designed PD shows polarization sensitivity at all incidence angles. The effects on absorptivity produced by the incidence angles, polarization angles, and materials are investigated. The amplitude of absorptivity change caused by polarization reaches 99.802%. A laser ablation process is adopted to prepare the designed PD on a FR-4 board coated with copper on the double plane with a thickness that was 1/93 and 1/48 of wavelength at a resonance frequency of 16.055 GHz and 30.9 GHz, respectively. The sample test results verify the designed PD excellent detectability on the polarization of the incident waves. The proposed PD, which greatly enriches the applications of metamaterials in bolometers, thermal images, stealth materials, microstructure measurements, and electromagnetic devices, is easy to mass produce and market because of its strong detectability, ultrathin thickness, effective cost, and convenient process. PMID:27455280

  13. An Omnidirectional Polarization Detector Based on a Metamaterial Absorber.

    Science.gov (United States)

    Zhang, Binzhen; Zhang, Yong; Duan, Junping; Zhang, Wendong; Wang, Wanjun

    2016-01-01

    The theory, design, simulation, fabrication, and performance of an omnidirectional polarization detector (PD) with two resonances located in the X and Ka ranges based on a metamaterial absorber (MMA) are presented in this paper. The sandwich structure of PD is composed of 0.1 μm periodic "I" shaped patches on the metasurface, a dielectric of 200 μm FR-4 on the interlayer, and a 0.3 μm copper film on the substrate. PD absorptivity is first used to reflect and describe the polarization of the incident wave. The numerical results, derived from the standard full wave finite integration technology (FIT) of CST 2015, indicates that the designed PD shows polarization sensitivity at all incidence angles. The effects on absorptivity produced by the incidence angles, polarization angles, and materials are investigated. The amplitude of absorptivity change caused by polarization reaches 99.802%. A laser ablation process is adopted to prepare the designed PD on a FR-4 board coated with copper on the double plane with a thickness that was 1/93 and 1/48 of wavelength at a resonance frequency of 16.055 GHz and 30.9 GHz, respectively. The sample test results verify the designed PD excellent detectability on the polarization of the incident waves. The proposed PD, which greatly enriches the applications of metamaterials in bolometers, thermal images, stealth materials, microstructure measurements, and electromagnetic devices, is easy to mass produce and market because of its strong detectability, ultrathin thickness, effective cost, and convenient process. PMID:27455280

  14. An Omnidirectional Polarization Detector Based on a Metamaterial Absorber

    Directory of Open Access Journals (Sweden)

    Binzhen Zhang

    2016-07-01

    Full Text Available The theory, design, simulation, fabrication, and performance of an omnidirectional polarization detector (PD with two resonances located in the X and Ka ranges based on a metamaterial absorber (MMA are presented in this paper. The sandwich structure of PD is composed of 0.1 μm periodic “I” shaped patches on the metasurface, a dielectric of 200 μm FR-4 on the interlayer, and a 0.3 μm copper film on the substrate. PD absorptivity is first used to reflect and describe the polarization of the incident wave. The numerical results, derived from the standard full wave finite integration technology (FIT of CST 2015, indicates that the designed PD shows polarization sensitivity at all incidence angles. The effects on absorptivity produced by the incidence angles, polarization angles, and materials are investigated. The amplitude of absorptivity change caused by polarization reaches 99.802%. A laser ablation process is adopted to prepare the designed PD on a FR-4 board coated with copper on the double plane with a thickness that was 1/93 and 1/48 of wavelength at a resonance frequency of 16.055 GHz and 30.9 GHz, respectively. The sample test results verify the designed PD excellent detectability on the polarization of the incident waves. The proposed PD, which greatly enriches the applications of metamaterials in bolometers, thermal images, stealth materials, microstructure measurements, and electromagnetic devices, is easy to mass produce and market because of its strong detectability, ultrathin thickness, effective cost, and convenient process.

  15. A resonance ionization imaging detector based on cesium atomic vapor

    International Nuclear Information System (INIS)

    A novel Cs resonance ionization imaging detector (RIID) has been developed and evaluated. The detector is capable of two-dimensional imaging with high spectral resolution, which is determined by the Doppler broadened atomic linewidth of Cs at given temperature. Ionization schemes of Cs have been investigated using dye and color center tunable lasers pumped by an excimer laser and by a Nd:YAG laser. It has been experimentally shown that the most efficient ionization scheme for Cs RIID should include a three-step excitation/ionization ladder, for example, with transitions at λ1=852.11 (852.113) nm, λ2=917.22 (917.2197) nm, and λ3=1064 nm. The imaging capabilities of the detector have been evaluated using a simpler two-step ionization scheme with wavelengths λ1=852.11 nm and λ2=508 nm

  16. A resonance ionization imaging detector based on cesium atomic vapor

    Science.gov (United States)

    Temirov, J. P.; Chigarev, N. V.; Matveev, O. I.; Omenetto, N.; Smith, B. W.; Winefordner, J. D.

    2004-05-01

    A novel Cs resonance ionization imaging detector (RIID) has been developed and evaluated. The detector is capable of two-dimensional imaging with high spectral resolution, which is determined by the Doppler broadened atomic linewidth of Cs at given temperature. Ionization schemes of Cs have been investigated using dye and color center tunable lasers pumped by an excimer laser and by a Nd:YAG laser. It has been experimentally shown that the most efficient ionization scheme for Cs RIID should include a three-step excitation/ionization ladder, for example, with transitions at λ1=852.11 (852.113) nm, λ2=917.22 (917.2197) nm, and λ3=1064 nm. The imaging capabilities of the detector have been evaluated using a simpler two-step ionization scheme with wavelengths λ1=852.11 nm and λ2=508 nm.

  17. Experimental research on the THGEM-based thermal neutron detector

    CERN Document Server

    Lei, Yang; Zhi-Jia, Sun; Ying, Zhang; Chao-Qiang, Huang; Guang-Ai, Sun; Yan-Feng, Wang; Gui-An, Yang; Hong, Xu; Yu-Guang, Xie; Yuan-Bo, Chen

    2014-01-01

    A new thermal neutron detector with the domestically produced THGEM (THick Gas Electron Multiplier) was developed as an alternative to 3He to meet the needs of the next generation of neutron facilities. One type of Au-coated THGEM was designed specifically for the neutron detection. A detector prototype had been developed and the preliminary experimental tests were presented, including the performance of the Au-coated THGEM working in the Ar/CO2 gas mixtures and the neutron imaging test with 252CF source, which would provide the reference of experimental data for the research in future.

  18. Experimental research on the THGEM-based thermal neutron detector

    OpenAIRE

    Lei, Yang; Jian-Rong, Zhou; Zhi-Jia, Sun; Ying, Zhang; Chao-Qiang, Huang; Guang-Ai, Sun; Yan-feng, Wang; Gui-An, Yang; HONG, XU; Yu-Guang, Xie; Yuan-Bo, Chen

    2014-01-01

    A new thermal neutron detector with the domestically produced THGEM (THick Gas Electron Multiplier) was developed as an alternative to 3He to meet the needs of the next generation of neutron facilities. One type of Au-coated THGEM was designed specifically for the neutron detection. A detector prototype had been developed and the preliminary experimental tests were presented, including the performance of the Au-coated THGEM working in the Ar/CO2 gas mixtures and the neutron imaging test with ...

  19. Ultra-fast silicon detectors (UFSD)

    Science.gov (United States)

    Sadrozinski, H. F.-W.; Anker, A.; Chen, J.; Fadeyev, V.; Freeman, P.; Galloway, Z.; Gruey, B.; Grabas, H.; John, C.; Liang, Z.; Losakul, R.; Mak, S. N.; Ng, C. W.; Seiden, A.; Woods, N.; Zatserklyaniy, A.; Baldassarri, B.; Cartiglia, N.; Cenna, F.; Ferrero, M.; Pellegrini, G.; Hidalgo, S.; Baselga, M.; Carulla, M.; Fernandez-Martinez, P.; Flores, D.; Merlos, A.; Quirion, D.; Mikuž, M.; Kramberger, G.; Cindro, V.; Mandić, I.; Zavrtanik, M.

    2016-09-01

    We report on measurements on Ultra-Fast Silicon Detectors (UFSD) which are based on Low-Gain Avalanche Detectors (LGAD). They are n-on-p sensors with internal charge multiplication due to the presence of a thin, low-resistivity diffusion layer below the junction, obtained with a highly doped implant. We have performed several beam tests with LGAD of different gain and report the measured timing resolution, comparing it with laser injection and simulations. For the 300 μm thick LGAD, the timing resolution measured at test beams is 120 ps while it is 57 ps for IR laser, in agreement with simulations using Weightfield2. For the development of thin sensors and their readout electronics, we focused on the understanding of the pulse shapes and point out the pivotal role the sensor capacitance plays.

  20. The 10 Tesla muSR instrument: detector solutions

    CERN Document Server

    Stoykov, A; Sedlak, K; Rodriguez, J; Greuter, U; Amato, A

    2012-01-01

    Solutions to the detector system of the High-Field muSR instrument at the Paul Scherrer Institut (PSI) in Switzerland are presented. The strict technical requirements are fulfilled through the application of Geiger-mode Avalanche Photodiodes.

  1. Monte Carlo simulation of a quantum noise limited Čerenkov detector based on air-spaced light guiding taper for megavoltage x-ray imaging

    Energy Technology Data Exchange (ETDEWEB)

    Teymurazyan, A. [Imaging Research, Sunnybrook Health Sciences Centre, Department of Medical Biophysics, University of Toronto, Toronto M4N 3M5 (Canada); Rowlands, J. A. [Imaging Research, Sunnybrook Health Sciences Centre, Department of Medical Biophysics, University of Toronto, Toronto M4N 3M5 (Canada); Thunder Bay Regional Research Institute (TBRRI), Thunder Bay P7A 7T1 (Canada); Department of Radiation Oncology, University of Toronto, Toronto M5S 3E2 (Canada); Pang, G., E-mail: geordi.pang@sunnybrook.ca [Imaging Research, Sunnybrook Health Sciences Centre, Department of Medical Biophysics, University of Toronto, Toronto M4N 3M5 (Canada); Department of Radiation Oncology, University of Toronto, Toronto M5S 3E2 (Canada); Odette Cancer Centre, Toronto M4N 3M5 (Canada); Department of Physics, Ryerson University, Toronto M5B 2K3 (Canada)

    2014-04-15

    Purpose: Electronic Portal Imaging Devices (EPIDs) have been widely used in radiation therapy and are still needed on linear accelerators (Linacs) equipped with kilovoltage cone beam CT (kV-CBCT) or MRI systems. Our aim is to develop a new high quantum efficiency (QE) Čerenkov Portal Imaging Device (CPID) that is quantum noise limited at dose levels corresponding to a single Linac pulse. Methods: Recently a new concept of CPID for MV x-ray imaging in radiation therapy was introduced. It relies on Čerenkov effect for x-ray detection. The proposed design consisted of a matrix of optical fibers aligned with the incident x-rays and coupled to an active matrix flat panel imager (AMFPI) for image readout. A weakness of such design is that too few Čerenkov light photons reach the AMFPI for each incident x-ray and an AMFPI with an avalanche gain is required in order to overcome the readout noise for portal imaging application. In this work the authors propose to replace the optical fibers in the CPID with light guides without a cladding layer that are suspended in air. The air between the light guides takes on the role of the cladding layer found in a regular optical fiber. Since air has a significantly lower refractive index (∼1 versus 1.38 in a typical cladding layer), a much superior light collection efficiency is achieved. Results: A Monte Carlo simulation of the new design has been conducted to investigate its feasibility. Detector quantities such as quantum efficiency (QE), spatial resolution (MTF), and frequency dependent detective quantum efficiency (DQE) have been evaluated. The detector signal and the quantum noise have been compared to the readout noise. Conclusions: Our studies show that the modified new CPID has a QE and DQE more than an order of magnitude greater than that of current clinical systems and yet a spatial resolution similar to that of current low-QE flat-panel based EPIDs. Furthermore it was demonstrated that the new CPID does not require an

  2. Evaluation of Compton gamma camera prototype based on pixelated CdTe detectors

    OpenAIRE

    Calderón, Y.; Chmeissani, M.; Kolstein, M.; De Lorenzo, G.

    2014-01-01

    A proposed Compton camera prototype based on pixelated CdTe is simulated and evaluated in order to establish its feasibility and expected performance in real laboratory tests. The system is based on module units containing a 2×4 array of square CdTe detectors of 10×10 mm2 area and 2 mm thickness. The detectors are pixelated and stacked forming a 3D detector with voxel sizes of 2 × 1 × 2 mm3. The camera performance is simulated with Geant4-based Architecture for Medicine-Oriented Simulations(G...

  3. Proximity focusing RICH detector based on multilayer silica aerogel radiator

    CERN Document Server

    De Leo, R; Bellunato, T; Calvi, M; Cisbani, E; Cusanno, F; Garibaldi, F; Lagamba, L; Marra, M; Marrone, S; Matteuzzi, C; Musico, P; Nappi, E; Perego, D L; Torrioli, S; Vilardi, I

    2010-01-01

    The performance of a proximity focusing Ring Imaging Cherenkov detector equipped with a radiator of silica aerogel is presented. The aerogel tile used is a monolith with variable index of refraction. Cherenkov photons are detected with high granularity by eight Hamamatsu H9500 flat panel multi anode phototubes.

  4. High-sensitivity CCD-based x-ray detector

    International Nuclear Information System (INIS)

    The detector is designed for imaging measurements requiring relatively high sensitivity and high spatial resolution. The detector can discriminate single X-ray photons, yet has the wide dynamic range (∼10000:1) associated with integrating detectors. A GdO2S2 phosphor screen converts the incoming X-ray image into an optical image. The optical image is coupled (without demagnification) to the CCD image sensor using a fiber optic faceplate. The CCD (Philips Semiconductors) has an area of 4.9 x 8.6 cm with 4000 x 7000 12 μm pixels. A single 12 keV X-ray photon produces a signal of 100 e-. With 2 x 2 pixel binning, the total noise per 24 μm pixel in a 100 s image is ∼30 e-, the detective quantum efficiency is >0.6 at 1 X-ray photon per pixel, and the full image can be read out in <4 s. The spatial resolution is 50 μm. The CCD readout system is fully computer-controlled, allowing flexible operation in time-resolved experiments. The detector has been characterized using visible-light images, X-ray images and time-resolved muscle diffraction measurements.

  5. Radiation effects on II-VI compound-based detectors

    CERN Document Server

    Cavallini, A; Dusi, W; Auricchio, N; Chirco, P; Zanarini, M; Siffert, P; Fougeres, P

    2002-01-01

    The performance of room temperature CdTe and CdZnTe detectors exposed to a radiation source can be strongly altered by the interaction of the ionizing particles and the material. Up to now, few experimental data are available on the response of II-VI compound detectors to different types of radiation sources. We have carried out a thorough investigation on the effects of gamma-rays, neutrons and electron irradiation both on CdTe : Cl and Cd sub 0 sub . sub 9 Zn sub 0 sub . sub 1 Te detectors. We have studied the detector response after radiation exposure by means of dark current measurements and of quantitative spectroscopic analyses at low and medium energies. The deep traps present in the material have been characterized by means of PICTS (photo-induced current transient spectroscopy) analyses, which allow to determine the trap apparent activation energy and capture cross-section. The evolution of the trap parameters with increasing irradiation doses has been monitored for all the different types of radiati...

  6. Detector Physics of Resistive Plate Chambers

    CERN Document Server

    Lippmann, Christian; Riegler, W

    2003-01-01

    Resistive Plate Chambers (RPCs) are gaseous parallel plate avalanche detectors that implement electrodes made from a material with a high volume resistivity between 10^7 and 10^12 Ohm cm. Large area RPCs with 2mm single gaps operated in avalanche mode provide above 98% efficiency and a time resolution of around 1ns up to a flux of several kHz/cm2. These Trigger RPCs will, as an example, equip the muon detector system of the ATLAS experiment at CERN on an area of 3650m2 and with 355.000 independent read out channels. Timing RPCs with a gas gap of 0.2 to 0.3mm are widely used in multi gap configurations and provide 99% efficiency and time resolution down to 50ps. While their performance is comparable to existing scintillator-based Time-Of-Flight (TOF) technology, Timing RPCs feature a significantly, up to an order of magnitude, lower price per channel. They will for example equip the 176m2 TOF barrel of the ALICE experiment at CERN with 160.000 independent read out cells. RPCs were originally operated in stream...

  7. AIGO: a southern hemisphere detector for the worldwide array of ground-based interferometric gravitational wave detectors

    Energy Technology Data Exchange (ETDEWEB)

    Barriga, P; Blair, D G; Coward, D; Davidson, J; Dumas, J-C; Howell, E; Ju, L; Wen, L; Zhao, C [School of Physics, The University of Western Australia, Crawley, WA 6009 (Australia); McClelland, D E; Scott, S M; Slagmolen, B J J; Inta, R [Department of Physics, Faculty of Science, Australian National University, Canberra, ACT 0200 (Australia); Munch, J; Ottaway, D J; Veitch, P; Hosken, D [Department of Physics, University of Adelaide, Adelaide, SA 5005 (Australia); Melatos, A; Chung, C; Sammut, L, E-mail: pbarriga@cyllene.uwa.edu.a [School of Physics University of Melbourne, Parkville, Vic 3010 (Australia)

    2010-04-21

    This paper describes the proposed AIGO detector for the worldwide array of interferometric gravitational wave detectors. The first part of the paper summarizes the benefits that AIGO provides to the worldwide array of detectors. The second part gives a technical description of the detector, which will follow closely the Advanced LIGO design. Possible technical variations in the design are discussed.

  8. Wave-like avalanche propagation in the continuum field model of self-organized criticality

    OpenAIRE

    Oh, Dong Keun; Jhang, Hogun

    2013-01-01

    Travelling wave is identified as the mechanism of avalanche propagation in the continuum SOC (self-organized critical) system. Recovering the hidden causality based on a generalization of Fick's law, we lead the equivalent continuum equation which has spatiotemporal nonlocality. Taking into account of the hyperbolicity from the retarded response of the nonlocal kernel, it is possible to capture the propagating avalanche in constant speed. Verifying the computation, we analyze the evolution of...

  9. Temporal correlations in neuronal avalanche occurrence

    Science.gov (United States)

    Lombardi, F.; Herrmann, H. J.; Plenz, D.; de Arcangelis, L.

    2016-04-01

    Ongoing cortical activity consists of sequences of synchronized bursts, named neuronal avalanches, whose size and duration are power law distributed. These features have been observed in a variety of systems and conditions, at all spatial scales, supporting scale invariance, universality and therefore criticality. However, the mechanisms leading to burst triggering, as well as the relationship between bursts and quiescence, are still unclear. The analysis of temporal correlations constitutes a major step towards a deeper understanding of burst dynamics. Here, we investigate the relation between avalanche sizes and quiet times, as well as between sizes of consecutive avalanches recorded in cortex slice cultures. We show that quiet times depend on the size of preceding avalanches and, at the same time, influence the size of the following one. Moreover we evidence that sizes of consecutive avalanches are correlated. In particular, we show that an avalanche tends to be larger or smaller than the following one for short or long time separation, respectively. Our analysis represents the first attempt to provide a quantitative estimate of correlations between activity and quiescence in the framework of neuronal avalanches and will help to enlighten the mechanisms underlying spontaneous activity.

  10. Development of an X-ray HARP–FEA detector system for high-throughput protein crystallography

    International Nuclear Information System (INIS)

    A new detector system for protein crystallography based on an X-ray HARP–FEA is presented. A new detector system for protein crystallography is now being developed based on an X-ray HARP–FEA (high-gain avalanche rushing amorphous photoconductor–field emitter array), which consists of an amorphous selenium membrane and a matrix field emitter array. The combination of the membrane avalanche effect with a single driven FEA has several advantages over currently available area detectors, including higher sensitivity, higher spatial resolution and a higher frame rate. Preliminary evaluation of the detector has been carried out and its effectiveness has been confirmed. Next, diffraction images were measured with continuous rotation of a protein crystal, and the images were compared with those measured by the existing CCD detector; the system successfully obtained high-spatial-resolution images. Using shutterless measurement, the total measurement time can be reduced significantly, making the method appropriate for high-throughput protein crystallography. The X-ray HARP–FEA detector is an attractive candidate for the next generation of X-ray area detectors

  11. Linking snow depth to avalanche release area size: measurements from the Vallée de la Sionne field site

    Science.gov (United States)

    Veitinger, Jochen; Sovilla, Betty

    2016-08-01

    One of the major challenges in avalanche hazard assessment is the correct estimation of avalanche release area size, which is of crucial importance to evaluate the potential danger that avalanches pose to roads, railways or infrastructure. Terrain analysis plays an important role in assessing the potential size of avalanche releases areas and is commonly based on digital terrain models (DTMs) of a snow-free summer terrain. However, a snow-covered winter terrain can significantly differ from its underlying, snow-free terrain. This may lead to different, and/or potentially larger release areas. To investigate this hypothesis, the relation between avalanche release area size, snow depth and surface roughness was investigated using avalanche observations of artificially triggered slab avalanches over a period of 15 years in a high-alpine field site. High-resolution, continuous snow depth measurements at times of avalanche release showed a decrease of mean surface roughness with increasing release area size, both for the bed surface and the snow surface before avalanche release. Further, surface roughness patterns in snow-covered winter terrain appeared to be well suited to demarcate release areas, suggesting an increase of potential release area size with greater snow depth. In this context, snow depth around terrain features that serve as potential delineation borders, such as ridges or trenches, appeared to be particularly relevant for release area size. Furthermore, snow depth measured at a nearby weather station was, to a considerable extent, related to potential release area size, as it was often representative of snow depth around those critical features where snow can accumulate over a long period before becoming susceptible to avalanche release. Snow depth - due to its link to surface roughness - could therefore serve as a highly useful variable with regard to potential release area definition for varying snow cover scenarios, as, for example, the avalanche

  12. Performance characteristics of a silicon photomultiplier based compact radiation detector for Homeland Security applications

    International Nuclear Information System (INIS)

    A next-generation compact radiation detector was studied for more accurate measurement of radiation and for improvement of detector reliability for the purpose of developing radiation protection technology and military applications. The previously used radiation detector had some limitations due to its bulky size, limited range and its environment for radiation measurement. On the other hand, the compact radiation detector examined in this study utilizes a silicon photomultiplier which appears to be more suitable for this application because of its physical superiority characterized by its small size, high sensitivity, and durability. Accordingly, a SiPM based scintillation detector has been developed as part of this basic study of military radiation detectors. The detector has been tested for its ability to obtain the operating characteristics of a sensor and analyzed with variations of parameter values and for efficiency of detection in accordance with its ability to measure radiation in the environment. Two SiPM based Scintillation detectors with LYSO, BGO and CsI:Tl scintillators were developed and the detectors were analyzed by a number of operating characteristics such as reverse bias, operating temperature and high magnetic field, that depend on environmental changes in radiation measurement. The Photon count rate and spectra were compared for these three scintillators. We found that there were variations in the radiation detection which were characterized by reverse bias, temperature and high magnetic field. It was also found that there was an 11.9% energy resolution for the LYSO, 15.5% for BGO and 13.5% for CsI:Tl using Array SiPM, and 18% for CsI:Tl energy resolution using single SiPM when we measured energy resolution of 511 keV for 22Na. These results demonstrate the potential widespread use of SiPM based compact radiation detectors for Homeland Security applications

  13. Design of a Silicon Photomultiplier Based Compact Radiation Detector for Homeland Security Screening

    International Nuclear Information System (INIS)

    Next-generation compact radiation detector was studied for more accurate measurement of radiation and improvement of reliability of the detector with purpose of developing of radiation protection technology and military application. The radiation detector which was used previously had some limitations due to the bulky size, limited range and the environment of radiation measurement. On the other hand, the compact radiation detector under this study which has adopted the silicon photomultiplier seems to be suitable for the application because of its physical excellence which are characterized by its small size, high sensitivity and durability. Accordingly, a SiPM based Scintillation detector has been made as a part of basic study of military radiation detector development. The detector has been tested for obtaining the operating characteristics of a sensor and analyzed with variation of parameter values and the efficiency of detection in accordance with the factor of measurement environment of radiation. The two SiPM based Scintillation detectors with the LYSO, BGO and CsI:Tl scintillator were made and the detectors were analyzed with the variation of operating characteristics as reverse bias, operating temperature and high magnetic field that are depend on environmental changes of radiation measurement. The results of three scintillators for a photon count rate and spectra were compared with each other. It was found that there are variations of radiation detection which are characterized by reverse bias, temperature and high magnetic field. Also, It was found that there were the 11.9 % for the LYSO, 15.5 % for BGO and 13.5 % for CsI:Tl energy resolution using array SiPM, and 18 % for CsI:Tl energy resolution using single SiPM, respectively when we measured energy resolution of 511 keV for 22Na. The results demonstrate the potential of SiPM based compact radiation detector to be used widely for Homeland Security applications. (authors)

  14. Performance characteristics of a silicon photomultiplier based compact radiation detector for Homeland Security applications

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hye Min, E-mail: ramilab2011@gmail.com; Joo, Koan Sik

    2015-05-01

    A next-generation compact radiation detector was studied for more accurate measurement of radiation and for improvement of detector reliability for the purpose of developing radiation protection technology and military applications. The previously used radiation detector had some limitations due to its bulky size, limited range and its environment for radiation measurement. On the other hand, the compact radiation detector examined in this study utilizes a silicon photomultiplier which appears to be more suitable for this application because of its physical superiority characterized by its small size, high sensitivity, and durability. Accordingly, a SiPM based scintillation detector has been developed as part of this basic study of military radiation detectors. The detector has been tested for its ability to obtain the operating characteristics of a sensor and analyzed with variations of parameter values and for efficiency of detection in accordance with its ability to measure radiation in the environment. Two SiPM based Scintillation detectors with LYSO, BGO and CsI:Tl scintillators were developed and the detectors were analyzed by a number of operating characteristics such as reverse bias, operating temperature and high magnetic field, that depend on environmental changes in radiation measurement. The Photon count rate and spectra were compared for these three scintillators. We found that there were variations in the radiation detection which were characterized by reverse bias, temperature and high magnetic field. It was also found that there was an 11.9% energy resolution for the LYSO, 15.5% for BGO and 13.5% for CsI:Tl using Array SiPM, and 18% for CsI:Tl energy resolution using single SiPM when we measured energy resolution of 511 keV for {sup 22}Na. These results demonstrate the potential widespread use of SiPM based compact radiation detectors for Homeland Security applications.

  15. Absolute efficiency measurements with the {sup 10}B based Jalousie detector

    Energy Technology Data Exchange (ETDEWEB)

    Modzel, G., E-mail: modzel@physi.uni-heidelberg [Physikalisches Institut, Universität Heidelberg, Neuenheimer Feld 226, 69120 Heidelberg (Germany); Henske, M. [CDT CASCADE Detector Technologies GmbH, Hans-Bunte-Str. 8–10, 69123 Heidelberg (Germany); Houben, A. [Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen (Germany); Klein, M. [Physikalisches Institut, Universität Heidelberg, Neuenheimer Feld 226, 69120 Heidelberg (Germany); CDT CASCADE Detector Technologies GmbH, Hans-Bunte-Str. 8–10, 69123 Heidelberg (Germany); Köhli, M.; Lennert, P. [Physikalisches Institut, Universität Heidelberg, Neuenheimer Feld 226, 69120 Heidelberg (Germany); Meven, M. [Heinz Maier-Leibnitz Zentrum (MLZ), 85747 Garching (Germany); Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science (JCNS), Outstation at MLZ, 85747 Garching (Germany); Schmidt, C.J. [CDT CASCADE Detector Technologies GmbH, Hans-Bunte-Str. 8–10, 69123 Heidelberg (Germany); GSI Detector Laboratory, Planckstr. 1, 64291 Darmstadt (Germany); Schmidt, U. [Physikalisches Institut, Universität Heidelberg, Neuenheimer Feld 226, 69120 Heidelberg (Germany); Schweika, W. [Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science (JCNS), 52425 Jülich (Germany); European Spallation Source ESS AB, SE-22100 Lund (Sweden)

    2014-04-11

    The {sup 10}B based Jalousie detector is a replacement for {sup 3}He counter tubes, which are nowadays less affordable for large area detectors due to the {sup 3}He crisis. In this paper we investigate and verify the performance of the new {sup 10}B based detector concept and its adoption for the POWTEX diffractometer, which is designed for the detection of thermal neutrons with predicted detection efficiencies of 75–50% for neutron energies of 10–100 meV, respectively. The predicted detection efficiency has been verified by absolute measurements using neutrons with a wavelength of 1.17 Å (59 meV)

  16. Pulse filtering and correction for CZT detectors using simple digital algorithms based on the wavelet transform

    International Nuclear Information System (INIS)

    The authors report an approach to double gaussian filtering used in classical works as dual parameter pulse processing. This technique has been implemented by creating a bank of gaussian-like digital filters based on wavelet transforms. A simple method to correct for the charge loss inherent to room temperature semiconductor gamma detectors has been developed. This method is based on multi-resolution signal analysis. Results are reported from tests of these algorithms on commercial CZT detectors and two trapped hole charge correction levels are compared. Finally, the advantages and limitations of this new approach to detector pulse processing are discussed

  17. FIR Detectors/Cameras Based on GaN and Si Field-Effect Devices Project

    Data.gov (United States)

    National Aeronautics and Space Administration — SETI proposes to develop GaN and Si based multicolor FIR/THz cameras with detector elements and readout, signal processing electronics integrated on a single chip....

  18. Optimal Filtering Algorithm-Based Multiuser Detector for Fast Fading CDMA Systems

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A multiuser detector was developed for fast fading code-division multiple-access systems by representing the channels as a system with the multiplicative noise (SMN) model and then using the known optimal filtering algorithm for the SMN for multiuser detection (MUD). This multiuser detector allows the channel response to be stochastic in one symbol duration, which can be regarded as an effective method of MUD for fast fading CDMA systems. Performance analyses show that the multiuser detector is theoretically valid for CDMA systems over fast fading channels. Simulations show that the multiuser detector performs better than the Kalman filter-based multiuser detector with a faster convergence rate and lower bit error rate.

  19. Geant4 based simulation of the Water Cherenkov Detectors of the LAGO Project

    CERN Document Server

    Calderón, R; Núñez, L A

    2015-01-01

    To characterize the signals registered by the different types of water Cherenkov detectors (WCD) used by the Latin American Giant Observatory (LAGO) Project, it is necessary to develop detailed simulations of the detector response to the flux of secondary particles at the detector level. These particles are originated during the interaction of cosmic rays with the atmosphere. In this context, the LAGO project aims to study the high energy component of gamma rays bursts (GRBs) and space weather phenomena by looking for the solar modulation of galactic cosmic rays (GCRs). Focus in this, a complete and complex chain of simulations is being developed that account for geomagnetic effects, atmospheric reaction and detector response at each LAGO site. In this work we shown the first steps of a GEANT4 based simulation for the LAGO WCD, with emphasis on the induced effects of the detector internal diffusive coating.

  20. Antenna-integrated 0.6 THz FET direct detectors based on CVD graphene.

    Science.gov (United States)

    Zak, Audrey; Andersson, Michael A; Bauer, Maris; Matukas, Jonas; Lisauskas, Alvydas; Roskos, Hartmut G; Stake, Jan

    2014-10-01

    We present terahertz (THz) detectors based on top-gated graphene field effect transistors (GFETs) with integrated split bow-tie antennas. The GFETs were fabricated using graphene grown by chemical vapor deposition (CVD). The THz detectors are capable of room-temperature rectification of a 0.6 THz signal and achieve a maximum optical responsivity better than 14 V/W and minimum optical noise-equivalent power (NEP) of 515 pW/Hz(0.5). Our results are a significant improvement over previous work on graphene direct detectors and are comparable to other established direct detector technologies. This is the first time room-temperature direct detection has been demonstrated using CVD graphene, which introduces the potential for scalable, wafer-level production of graphene detectors. PMID:25203787

  1. Influence of field effect on the performance of InGaAs-based terahertz radiation detectors

    CERN Document Server

    Minkevičius, Linas; Kojelis, Martynas; Žąsinas, Ernestas; Bukauskas, Virginijus; Šetkus, Arūnas; Kašalynas, Irmantas; Valušis, Gintaras

    2016-01-01

    Detailed electric characterization of high-performance InGaAs-based terahertz radiation detectors and corresponding simulation results are presented. The local surface potential and tunneling current were scanned on the surface of detectors by Kelvin probe force microscope (KPFM) and scanning tunneling microscope (STM) and a position of the Fermi level was obtained from these experiments. Current-voltage curves were measured and modelled using Synopsys Sentaurus TCAD package to get a better insight of processes happening within the detector. In addition, finite-difference time-domain simulations were performed to reveal the peculiarities of electric field concentration by the metal contacts of the detectors. Results of our investigation confirm, that field-effect induced conductivity modulation is a possible contributing mechanism to high sensitivity of the detectors.

  2. A directional gamma-ray detector based on scintillator plates

    Energy Technology Data Exchange (ETDEWEB)

    Hanna, D., E-mail: hanna@physics.mcgill.ca; Sagnières, L.; Boyle, P.J.; MacLeod, A.M.L.

    2015-10-11

    A simple device for determining the azimuthal location of a source of gamma radiation, using ideas from astrophysical gamma-ray burst detection, is described. A compact and robust detector built from eight identical modules, each comprising a plate of CsI(Tl) scintillator coupled to a photomultiplier tube, can locate a point source of gamma rays with degree-scale precision by comparing the count rates in the different modules. Sensitivity to uniform environmental background is minimal.

  3. Novel Boron-10-based detectors for Neutron Scattering Science

    OpenAIRE

    Piscitelli, Francesco; project, for the ILL/ESS/LiU collaboration for the development of the B10 detector technology in the framework of the CRISP

    2015-01-01

    Nowadays neutron scattering science is increasing its instrumental power. Most of the neutron sources in the world are pushing the development of their technologies to be more performing. The neutron scattering development is also pushed by the European Spallation Source (ESS) in Sweden, a neutron facility which has just started construction. Concerning small area detectors (1m^2), the 3He technology, which is today cutting edge, is reaching fundamental limits in its development. Counting rat...

  4. Novel Boron-10-based detectors for Neutron Scattering Science

    CERN Document Server

    Piscitelli, Francesco

    2015-01-01

    Nowadays neutron scattering science is increasing its instrumental power. Most of the neutron sources in the world are pushing the development of their technologies to be more performing. The neutron scattering development is also pushed by the European Spallation Source (ESS) in Sweden, a neutron facility which has just started construction. Concerning small area detectors (1m^2), the 3He technology, which is today cutting edge, is reaching fundamental limits in its development. Counting rate capability, spatial resolution and cost-e?ectiveness, are only a few examples of the features that must be improved to ful?fill the new requirements. On the other hand, 3He technology could still satisfy the detector requirements for large area applications (50m^2), however, because of the present 3He shortage that the world is experiencing, this is not practical anymore. The recent detector advances (the Multi-Grid and the Multi-Blade prototypes) developed in the framework of the collaboration between the Institut Laue...

  5. Polycrystalline diamond based detector for Z-pinch diagnosis

    International Nuclear Information System (INIS)

    Full text of publication follows: Z-pinch is a self-constricted plasma configuration, as well as a high efficient X-ray simulator with energy transfer coefficient in the range of 0.8% - 23% [1-4]. Characteristics of the X-ray from Z-pinch are very important for researches focusing on the physical processes of plasma [5-6]. A chemical vapour deposition (CVD) derived polycrystalline diamond film detector has been developed as the X-ray detector on Z-pinch at a high powerful pulsed electron beam accelerator named Qiangguang-I (current 1.4-2.1 MA, rising time 80-100 ns) in Northwest Institute of Nuclear Technology in P. R. China. This detector is 16 mm in diameter and 300 μm in thickness with gold electrodes on both sides. The dark current of the detector is lower than 60 pA with the electric field intensity of 3 V/μm. The charge collection efficiency is 60.8% with the electric field intensity of 1.67 V/μm. The energy response and the time response have been studied by both experiments and theoretical calculation. The spectral response to X-ray is flat over the range of 3-5 keV. The rising time of response pulse is 2-3 ns. This diamond detector acquires good experimental data which are in good agreement with the results got from the X-ray Diodes (XRDs) [7] on Z-pinch diagnosis at Qiangguang-I facility. These results show that the device we developed offers a good choice for Z-pinch diagnosis at high power electron beam accelerator. References: [1] R. B. Spielman, C. Deeney and G. A. Chandler, Phys of Plasmas 5, 5 (1998); [2] Proceedings of 10. IEEE International Pulsed Power Conference 1995, 1-2; [3] Proceedings of 11. IEEE International Pulsed Power Conference 1997, 23-36; [4] A. Qiu, Engineering Science 2, 9(2000); [5] A. Qiu, B. Kuai and Z. Zeng, Acta Physica Sinica 55, 11 (2006); [6] W. Wang, D. He and A. Qiu, High Power Laser and Particle Beams 15, 184(2003); [7] G. A. Chandler, C. Deeney and M. Cuneo, Review of Scientific Instruments 70, 1(1999). (authors)

  6. Catastrophic avalanches and methods of their control

    Directory of Open Access Journals (Sweden)

    N. A. Volodicheva

    2014-01-01

    Full Text Available Definition of such phenomenon as “catastrophic avalanche” is presented in this arti-cle. Several situations with releases of catastrophic avalanches in mountains of Caucasus, Alps, and Central Asia are investigated. Materials of snow-avalanche ob-servations performed since 1960s at the Elbrus station of the Lomonosov Moscow State University (Central Caucasus were used for this work. Complex-valued measures of engineering protection demonstrating different efficiencies are consid-ered.

  7. Characterization of the QUartz Photon Intensifying Detector (QUPID) for use in Noble Liquid Detectors

    CERN Document Server

    Teymourian, A; Baudis, L; Beltrame, P; Brown, E; Cline, D; Ferella, A D; Fukasawa, A; Lam, C W; Lim, T; Lung, K; Meng, Y; Muramatsu, S; Pantic, E; Suyama, M; Wang, H; Arisaka, K

    2011-01-01

    Dark Matter and Double Beta Decay experiments require extremely low radioactivity within the detector materials. For this purpose, the University of California, Los Angeles and Hamamatsu Photonics have developed the QUartz Photon Intensifying Detector (QUPID), an ultra-low background photodetector based on the Hybrid Avalanche Photo Diode (HAPD) and entirely made of ultraclean synthetic fused silica. In this work we present the basic concept of the QUPID and the testing measurements on Qupids from the first production line. Screening of radioactivity at the Gator facility in the Laboratori Nazionali del Gran Sasso has shown that the QUPIDs safely fulfill the low radioactive contamination requirements for the next generation zero background experiments set by Monte Carlo simulations. The quantum efficiency of the QUPID at room temperature is > 30% at the xenon scintillation wavelength. At low temperatures, the QUPID shows a leakage current less than 1 nA and a global gain of 10^5. In these conditions, the phot...

  8. Some influences of rock strength and strain rate on propagation of rock avalanches

    Science.gov (United States)

    Bowman, Elisabeth; Rait, Kim

    2016-04-01

    Rock avalanches are extreme and destructive mass movements in which large volumes of rock (typically >1 million cubic metres) travel at high speeds, covering large distances, and the occurrence of which is highly unpredictable. The "size effect" in rock avalanches, whereby those with larger volumes produce greater spreading efficiency (as defined by an increase in normalised runout) or lower farboschung angle (defined as the tangent of the ratio of fall height to runout length), is well known. Studies have shown that rock strength is a controlling factor in the mobility of rock avalanches - that is, mass movements involving lower strength rock are generally found to produce greater mobility as evidenced by the spread of deposits or low farboschung angle. However, there are conflicting ideas as to how and why this influence is manifested. This paper discusses different theories of rock comminution in light of numerical simulations of rock clasts undergoing normal and shear induced loading, experimental work on rock avalanche behaviour, and dynamic fracture mechanics. In doing so, we introduce the idea of thresholds of strain rate for the production of dynamic fragmentation (as opposed to pseudo-static clast crushing) that are based, inter alia, on static rock strength. To do this, we refer to data from physical models using rock analogue materials, field data on chalk cliff collapses, and field statistics from documented rock avalanches. The roles of normal and shear loading and loading rate within a rock avalanche are examined numerically using 3D Discrete Element Method models of rock clasts loaded to failure. Results may help to reconcile the observations that large rock avalanches in stronger materials tend not to fragment as much as those in weaker materials and also possess lower mobility, while small cliff collapses (typically > 1000 cubic metres) in weak chalk can exhibit rock avalanche-like behaviour at much smaller volumes.

  9. Spatial resolution of a μPIC-based neutron imaging detector

    Energy Technology Data Exchange (ETDEWEB)

    Parker, J.D., E-mail: jparker@cr.scphys.kyoto-u.ac.jp [Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa-oiwakecho, Sakyo-ku, Kyoto 606-8502 (Japan); Harada, M. [Materials and Life Science Facility Division, Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki 319-1195 (Japan); Hattori, K.; Iwaki, S.; Kabuki, S.; Kishimoto, Y.; Kubo, H.; Kurosawa, S.; Matsuoka, Y.; Miuchi, K.; Mizumoto, T.; Nishimura, H. [Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa-oiwakecho, Sakyo-ku, Kyoto 606-8502 (Japan); Oku, T. [Materials and Life Science Facility Division, Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki 319-1195 (Japan); Sawano, T. [Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa-oiwakecho, Sakyo-ku, Kyoto 606-8502 (Japan); Shinohara, T.; Suzuki, J. [Materials and Life Science Facility Division, Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki 319-1195 (Japan); Takada, A.; Tanimori, T.; Ueno, K. [Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa-oiwakecho, Sakyo-ku, Kyoto 606-8502 (Japan)

    2013-10-21

    We present a detailed study of the spatial resolution of our time-resolved neutron imaging detector utilizing a new neutron position reconstruction method that improves both spatial resolution and event reconstruction efficiency. Our prototype detector system, employing a micro-pattern gaseous detector known as the micro-pixel chamber (μPIC) coupled with a field-programmable-gate-array-based data acquisition system, combines 100μm-level spatial and sub-μs time resolutions with excellent gamma rejection and high data rates, making it well suited for applications in neutron radiography at high-intensity, pulsed neutron sources. From data taken at the Materials and Life Science Experimental Facility within the Japan Proton Accelerator Research Complex (J-PARC), the spatial resolution was found to be approximately Gaussian with a sigma of 103.48±0.77μm (after correcting for beam divergence). This is a significant improvement over that achievable with our previous reconstruction method (334±13μm), and compares well with conventional neutron imaging detectors and with other high-rate detectors currently under development. Further, a detector simulation indicates that a spatial resolution of less than 60μm may be possible with optimization of the gas characteristics and μPIC structure. We also present an example of imaging combined with neutron resonance absorption spectroscopy. -- Highlights: • Neutron imaging detector with micro-pattern gaseous detector and {sup 3}He was developed. • Detector combines imaging with energy by time-of-flight and high-rate capability. • Detector features 18% efficiency, 0.6μs time resolution, and γ sensitivity <10{sup −12}. • New analysis method with template fit achieves spatial resolution of nearly 100μm. • Simulation study indicates improvement to ∼60μm after optimization.

  10. Spatial resolution of a μPIC-based neutron imaging detector

    International Nuclear Information System (INIS)

    We present a detailed study of the spatial resolution of our time-resolved neutron imaging detector utilizing a new neutron position reconstruction method that improves both spatial resolution and event reconstruction efficiency. Our prototype detector system, employing a micro-pattern gaseous detector known as the micro-pixel chamber (μPIC) coupled with a field-programmable-gate-array-based data acquisition system, combines 100μm-level spatial and sub-μs time resolutions with excellent gamma rejection and high data rates, making it well suited for applications in neutron radiography at high-intensity, pulsed neutron sources. From data taken at the Materials and Life Science Experimental Facility within the Japan Proton Accelerator Research Complex (J-PARC), the spatial resolution was found to be approximately Gaussian with a sigma of 103.48±0.77μm (after correcting for beam divergence). This is a significant improvement over that achievable with our previous reconstruction method (334±13μm), and compares well with conventional neutron imaging detectors and with other high-rate detectors currently under development. Further, a detector simulation indicates that a spatial resolution of less than 60μm may be possible with optimization of the gas characteristics and μPIC structure. We also present an example of imaging combined with neutron resonance absorption spectroscopy. -- Highlights: • Neutron imaging detector with micro-pattern gaseous detector and 3He was developed. • Detector combines imaging with energy by time-of-flight and high-rate capability. • Detector features 18% efficiency, 0.6μs time resolution, and γ sensitivity −12. • New analysis method with template fit achieves spatial resolution of nearly 100μm. • Simulation study indicates improvement to ∼60μm after optimization

  11. Digital X-ray detector based on a CCD matrix

    International Nuclear Information System (INIS)

    The application of charge-coupled devices (CCD) as position-sensitive detectors for X-ray radiation is discussed. The experimental scheme contains a videotransmission camera to detect pulsed X-ray radiation and Vektor analog-to-digital converters and computer interface. It is shown that the sensitivity range of a K1200TsM1 matrix to bremsstrahlung with an average energy of 75 keV is 2.7·10-8-0.8·10-6 J/cm2. The spatial resolution of the resultant X-ray image is discussed. 5 refs., 5 figs

  12. Smartphone based point-of-care detector of urine albumin

    Science.gov (United States)

    Cmiel, Vratislav; Svoboda, Ondrej; Koscova, Pavlina; Provaznik, Ivo

    2016-03-01

    Albumin plays an important role in human body. Its changed level in urine may indicate serious kidney disorders. We present a new point-of-care solution for sensitive detection of urine albumin - the miniature optical adapter for iPhone with in-built optical filters and a sample slot. The adapter exploits smart-phone flash to generate excitation light and camera to measure the level of emitted light. Albumin Blue 580 is used as albumin reagent. The proposed light-weight adapter can be produced at low cost using a 3D printer. Thus, the miniaturized detector is easy to use out of lab.

  13. Combined detectors of charged particles based on zinc selenide scintillators and silicon photodiodes

    CERN Document Server

    Ryzhikov, V D; Starzhinskij, N G

    2001-01-01

    combined detectors of charged particles are described based on zinc selenide (Zn Se(Te)) crystals,silicon photodiodes and charges-sensitive amplifiers. Zn Se(Te) scintillators are characterized by high alpha to beta ratio (approx 1.0), good scintillation efficiency (up to 22%),and high radiation stability (up to 100 Mrad),together with good spectral matching with silicon PIN photodiodes. The signal coming from the photodiode in the two modes (photoreceiver and semiconductor detector) differ in the amplitude values and pulse duration, which opens new possibilities for development and application of such combined detectors.

  14. Robust PCA-Based Abnormal Traffic Flow Pattern Isolation and Loop Detector Fault Detection

    Institute of Scientific and Technical Information of China (English)

    JIN Xuexiang; ZHANG Yi; LI Li; HU Jianming

    2008-01-01

    One key function of intelligent transportation systems is to automatically detect abnormal traffic phenomena and to help further investigations of the cause of the abnormality. This paper describes a robust principal components analysis (RPCA)-based abnormal traffic flow pattern isolation and loop detector fault detection method. The results show that RPCA is a useful tool to distinguish regular traffic flow from abnor-mal traffic flow patterns caused by accidents and loop detector faults. This approach gives an effective traffic flow data pre-processing method to reduce the human effort in finding potential loop detector faults. The method can also be used to further investigate the causes of the abnormality.

  15. Discriminating cosmic muon and x-ray based on rising time using GEM detector

    OpenAIRE

    Hui-Yin, Wu; Sheng-Ying, Zhao; Xiao-Dong, Wang; Xian-Ming, Zhang; Hui-Rong, Qi; Wei, Zhang; Ke-Yan, Wu; Bi-Tao, Hu; Yi, Zhang

    2015-01-01

    Gas electron multiplier(GEM) detector is used in Cosmic Muon Scattering Tomography and neutron imaging in the last decade. In this work, a triple GEM device with an effective readout area of 10 cm X 10 cm is developed, and an experiment of discriminating between cosmic muon and x-ray based on rising time is tested. The energy resolution of GEM detector is tested by 55Fe ray source to prove the GEM detector has a good performance. The analysis of the complete signal-cycles allows to get the ri...

  16. 32 Bin Near-Infrared Time-Multiplexing Detector with Attojoule Single-Shot Energy Resolution

    CERN Document Server

    Eraerds, Patrick; Pomarico, Enrico; Sanguinetti, Bruno; Thew, Rob; Zbinden, Hugo

    2010-01-01

    We present two implementations of photon counting time-multiplexing detectors for near-infrared wavelengths, based on Peltier cooled InGaAs/InP avalanche photo diodes (APDs). A first implementation is motivated by practical considerations using only commercially available components. It features 16 bins, pulse repetition rates of up to 22 kHz and a large range of applicable pulse widths of up to 100 ns. A second implementation is based on rapid gating detectors, permitting deadtimes below 10 ns. This allows one to realize a high dynamic-range 32 bin detector, able to process pulse repetition rates of up to 6 MHz for pulse width of up to 200 ps. Analysis of the detector response at 16.5% detection efficiency, reveals a single-shot energy resolution on the attojoule level.

  17. Development of a reader for track etch detectors based on a commercially available slide scanner

    CERN Document Server

    Steele, J D; Tanner, R J; Bartlett, D T

    1999-01-01

    NRPB has operated a routine neutron personal dosimetry service based on the electrochemical etch of PADC elements since 1986. Since its inception it has used an automated reader based on a video camera and real time analysis. A new and more powerful replacement system has been developed using a commercially available photographic slide scanner. This permits a complete image of the dosemeter to be grabbed in a single scan, generating a 2592x3888 pixel file which is saved for subsequent analysis. This gives an effective pixel size of 10x10 mu m with an image of the entire dosemeter in one field of view. Custom written software subsequently analyses the image to assess the number of etched pits on the dosemeter and read the detector identification number (code). Batch scanning of up to 40 detectors is also possible using an autofeed attachment. The system can be used for electrochemically etched tracks for neutron detectors and chemically etched tracks for radon detectors.

  18. Proton recoil telescope based on diamond detectors for measurement of fusion neutrons

    CERN Document Server

    Caiffi, B; Ripani, M; Pillon, M; Taiuti, M

    2015-01-01

    Diamonds are very promising candidates for the neutron diagnostics in harsh environments such as fusion reactor. In the first place this is because of their radiation hardness, exceeding that of Silicon by an order of magnitude. Also, in comparison to the standard on-line neutron diagnostics (fission chambers, silicon based detectors, scintillators), diamonds are less sensitive to $\\gamma$ rays, which represent a huge background in fusion devices. Finally, their low leakage current at high temperature suppresses the detector intrinsic noise. In this talk a CVD diamond based detector has been proposed for the measurement of the 14 MeV neutrons from D-T fusion reaction. The detector was arranged in a proton recoil telescope configuration, featuring a plastic converter in front of the sensitive volume in order to induce the (n,p) reaction. The segmentation of the sensitive volume, achieved by using two crystals, allowed to perform measurements in coincidence, which suppressed the neutron elastic scattering backg...

  19. New scintillating media based on liquid crystals for particle detectors

    CERN Document Server

    Barnik, M I; Vasilchenko, V G; Golovkin, S V; Medvedkov, A M; Soloviev, A S

    2000-01-01

    The study results of optical, photoluminiscent and scintillation properties of a liquid crystal 4-pentyl-4'-cyanobiphenyl are presented. The scintillation light output of this liquid crystal is about 35% of crystal anthracene, its main decay time constants are 4 and 14 ns, and the maximum of light emission spectrum is about 400 nm. The light output of a dissolution of green emitting light scintillation dopant R6 in the liquid crystal is about 120% of crystal anthracene. The light output of the frozen dissolution measured at -112 deg. C is about 2.5 times higher as observed at +20 deg. C. In the uniaxially oriented liquid crystal, the predominant intensity direction of emitted light is pointed perpendicular to the liquid crystal director and an appreciable part of the emitted light is elliptically polarized. The possibility to use scintillation properties of liquid crystals is considered both for the improvement of existing particle detector characteristics and for the creation of new gated particle detectors.

  20. TORCH - a Cherenkov-based time-of-flight detector

    CERN Document Server

    van Dijk, M W U; Cowie, E N; Cussans, D; D' Ambrosio, C; Forty, R; Frei, C; Gys, T; Piedigrossi, D; Castillo Garcia, L; Fopma, J; Gao, R; Harnew, N; Keri, T

    2014-01-01

    TORCH is an innovative high-precision time-of-flight system to provide particle identification in the difficult intermediate momentum region up to 10 GeV/c. It is also suitable for large-area applications. The detector provides a time-of-flight measurement from the imaging of Cherenkov photons emitted in a 1 cm thick quartz radiator. The photons propagate by total internal reflection to the edge of the quartz plate, where they are focused onto an array of photon detectors at the periphery. A time-of-flight resolution of about 10–15 ps per incident charged particle needs to be achieved for a three sigma kaon–pion separation up to 10 GeV/c momentum for the TORCH located 9.5 m from the interaction point. Given ∼ 30 detected photons per incident charged particle, this requires measuring the time-of-arrival of individual photons to about 70 ps. This paper will describe the design of a TORCH prototype involving a number of ground-breaking and challenging techniques.

  1. Track detector based dosimetry for therapeutic carbon beams

    CERN Document Server

    Osinga, J -M; Brabcová, K Pachnerová; Akselrod, M S; Jäkel, O; Davídková, M; Greilich, S

    2013-01-01

    The ability of plastic and fluorescent nuclear track detectors (PNTDs and FNTDs) to measure fluence and the linear energy transfer (LET) of clinical carbon ion beams was investigated. We employed coincident measurements with both systems and registered the results at the level of single tracks. Irradiations were performed in the entrance channel of the monoenergetic carbon ion beam covering the therapeutically useful energy range from 80 to 425 MeV/u. About 99 % of all primary particle tracks detected by both detectors were successfully matched, while 1 % of the particles were only detected by the FNTDs because of their superior spatial resolution. We conclude that both PNTDs and FNTDs are suitable for clinical carbon beam dosimetry with a detection efficiency of at least 98.82 % and 99.83 % respectively, if irradiations are performed with low fluence in the entrance channel of the ion beam. Additionally, a relationship between the mean LET as determined with PNTDs and the mean fluorescence amplitude of the p...

  2. High dynamic range CMOS-based mammography detector for FFDM and DBT

    Science.gov (United States)

    Peters, Inge M.; Smit, Chiel; Miller, James J.; Lomako, Andrey

    2016-03-01

    Digital Breast Tomosynthesis (DBT) requires excellent image quality in a dynamic mode at very low dose levels while Full Field Digital Mammography (FFDM) is a static imaging modality that requires high saturation dose levels. These opposing requirements can only be met by a dynamic detector with a high dynamic range. This paper will discuss a wafer-scale CMOS-based mammography detector with 49.5 μm pixels and a CsI scintillator. Excellent image quality is obtained for FFDM as well as DBT applications, comparing favorably with a-Se detectors that dominate the X-ray mammography market today. The typical dynamic range of a mammography detector is not high enough to accommodate both the low noise and the high saturation dose requirements for DBT and FFDM applications, respectively. An approach based on gain switching does not provide the signal-to-noise benefits in the low-dose DBT conditions. The solution to this is to add frame summing functionality to the detector. In one X-ray pulse several image frames will be acquired and summed. The requirements to implement this into a detector are low noise levels, high frame rates and low lag performance, all of which are unique characteristics of CMOS detectors. Results are presented to prove that excellent image quality is achieved, using a single detector for both DBT as well as FFDM dose conditions. This method of frame summing gave the opportunity to optimize the detector noise and saturation level for DBT applications, to achieve high DQE level at low dose, without compromising the FFDM performance.

  3. Study on the imaging ability of the 2D neutron detector based on MWPC

    OpenAIRE

    LiChao, Tian; YuanBo, Chen; Bin, Tang; JianRong, Zhou; HuiRong, Qi; RongGuang, Liu; Zhang JIAN; GuiAn, Yang; HONG, XU; DongFeng, Chen; ZhiJia, Sun

    2013-01-01

    A 2D neutron detector based on 3He convertor and MWPC with an active area of 200 mm \\times 200 mm has been successfully designed and fabricated. The detector has been tested with Am/Be neutron source and with collimated neutron beam with wavelength of {\\lambda} = 1.37 {\\AA}. A best spatial resolution of 1.18 mm (FWHM) and good linearity were obtained. This is in good agreement with the theoretical calculations.

  4. Development of a mini high efficiency neutron detector based on 6LiI (Eu) scintillator

    International Nuclear Information System (INIS)

    A mini neutron detector with the dimension of φ25 mm ×20 mm is developed based on a 6LiI( Eu) scintillator with a Hamamatsu S3590-08 photodiode. The detector was used to detect thermal neutrons from a paraffin shielded 252Cf neutron source and the detect efficiency to thermal neutron was calculated to be 95% with a resolution of thermal neutron peak about 16%. (authors)

  5. Low dark count geiger mode avalanche photodiodes fabricated in conventional CMOS technologies

    OpenAIRE

    Vilella Figueras, Eva; Arbat Casas, Anna; Alonso Casanovas, Oscar; Comerma Montells, Albert; Trenado, J.; Vilà i Arbonès, Anna Maria; Casanova Mohr, Raimon; Garrido Beltrán, Lluís; Diéguez Barrientos, Àngel

    2011-01-01

    Avalanche photodiodes operated in the Geiger mode present very high intrinsic gain and fast time response, which make the sensor an ideal option for those applications in which detectors with high sensitivity and velocity are required. Moreover, they are compatible with conventional CMOS technologies, allowing sensor and front-end electronics integration within the pixel cell. Despite these excellent qualities, the photodiode suffers from high intrinsic noise, which degrades the performance o...

  6. Gamma-Free Neutron Detector Based upon Lithium Phosphate Nanoparticles

    International Nuclear Information System (INIS)

    A gamma-free neutron-sensitive scintillator is needed to enhance radiation sensing and detection for nonproliferation applications. Such a scintillator would allow very large detectors to be placed at the perimeter of spent-fuel storage facilities at commercial nuclear power plants, so that any movement of spontaneously emitted neutrons from spent nuclear fuel or weapons grade plutonium would be noted in real-time. This task is to demonstrate that the technology for manufacturing large panels of fluor-doped plastic containing lithium-6 phosphate nanoparticles can be achieved. In order to detect neutrons, the nanoparticles must be sufficiently small so that the plastic remains transparent. In this way, the triton and alpha particles generated by the capture of the neutron will result in a photon burst that can be coupled to a wavelength shifting fiber (WLS) producing an optical signal of about ten nanoseconds duration signaling the presence of a neutron emitting source

  7. A large area, silicon photomultiplier-based PET detector module

    Science.gov (United States)

    Raylman, R. R.; Stolin, A.; Majewski, S.; Proffitt, J.

    2014-01-01

    The introduction of silicon photomultipliers (SiPM) has facilitated construction of compact, efficient and magnetic field-hardened positron emission tomography (PET) scanners. To take full advantage of these devices, methods for using them to produce large field-of-view PET scanners are needed. In this investigation, we explored techniques to combine two SiPM arrays to form the building block for a small animal PET scanner. The module consists of a 26×58 array of 1.5×1.5 mm2 LYSO elements (spanning 41×91 mm2) coupled to two SensL SiPM arrays. The SiPMs were read out with new multiplexing electronics developed for this project. To facilitate calculation of event position with multiple SiPM arrays it was necessary to spread scintillation light amongst a number of elements with a small light guide. This method was successful in permitting identification of all detector elements, even at the seam between two SiPM arrays. Since the performance of SiPMs is enhanced by cooling, the detector module was fitted with a cooling jacket, which allowed the temperature of the device and electronics to be controlled. Testing demonstrated that the peak-to-valley contrast ratio of the light detected from the scintillation array was increased by ~45% when the temperature was reduced from 28 °C to 16 °C. Energy resolution for 511 keV photons improved slightly from 18.8% at 28 °C to 17.8% at 16 °C. Finally, the coincidence timing resolution of the module was found to be insufficient for time-of-flight applications (~2100 ps at 14 °C). The first use of these new modules will be in the construction of a small animal PET scanner to be integrated with a 3 T clinical magnetic resonance imaging scanner.

  8. Monitoring of full-depth avalanches contaminated by soil and rocks - their origin and consequences, (Krkonose/Karkonosze Mts.- High Sudetes)

    Science.gov (United States)

    Kocianova, M.

    2009-04-01

    Monitoring of full-depth avalanches contaminated by soil and rocks - their origin and consequences, (Krkonose/Karkonosze Mts.- High Sudetes) Milena Kocianova Valerian Spusta, Irena Spatenkova, Alena Tondrova, Igor Jan Dvorak, Vlastimil Pilous Krkonoše National Park Administration, Dobrovskeho 3, 543 01 Vrchlabi, Czech republic Monitoring of snow avalanches is provided in Czech part of the Krkonose/Karkonosze Mountains since the winter season 1961/62. The full-depth avalanches contaminated by soil and rocks represent about 4% of the monitored number. There are six bigger avalanches of this type recorded during last 10 years. The areas of snutched weathering mantles reached at about 3000 - 23 000 m2 per individual avalanche track. In deposit zones the areas from 2600 to 18700 m2 were covered by soil, sods and small rock fragments whose volume ranged from about 130 to 880 m3 per individual avalanche track. The volume of large rock fragments in one concrete track was counted up to 144 m3. The great influence of full depth avalanches on relief and slope development is evident. Based on monitoring the speed of snutched areas overgrowing by vegetation and on comparison of space design of plant communities out off and on the avalanche tracks respectively, it would be possible to estimate the period of such bigger events. Very important thing is that four avalanche events were triggered by water, which infiltrated the base of snowpack within upper or central parts of avalanche slopes. Water origin was probably either a) in mires on adjacent summit plateau (ground water flown on inclined bedrock layers to the avalanche slopes) and b) in thawing water of snow patches situated on the cryoplanation terraces above the avalanche slopes. More detailed study of these phenomena is needed in the future.

  9. Optimization of a bolometer detector for ITER based on Pt absorber on SiN membrane.

    Science.gov (United States)

    Meister, H; Eich, T; Endstrasser, N; Giannone, L; Kannamüller, M; Kling, A; Koll, J; Trautmann, T; Detemple, P; Schmitt, S

    2010-10-01

    Any plasma diagnostic in ITER must be able to operate at temperatures in excess of 200 °C and neutron loads corresponding to 0.1 dpa over its lifetime. To achieve this aim for the bolometer diagnostic, a miniaturized metal resistor bolometer detector based on Pt absorbers galvanically deposited on SiN membranes is being developed. The first two generations of detectors featured up to 4.5 μm thick absorbers. Results from laboratory tests are presented characterizing the dependence of their calibration constants under thermal loads up to 450 °C. Several detectors have been tested in ASDEX Upgrade providing reliable data but also pointing out the need for further optimization. A laser trimming procedure has been implemented to reduce the mismatch in meander resistances below 1% for one detector and the thermal drifts from this mismatch.

  10. OFDM Signal Detector Based on Cyclic Autocorrelation Function and its Properties

    Directory of Open Access Journals (Sweden)

    Z. Fedra

    2011-12-01

    Full Text Available This paper is devoted to research of the general and particular properties of the OFDM signal detector based on the cyclic autocorrelation function. The cyclic autocorrelation function is estimated using DFT. The parameters of the testing signal have been chosen according to 802.11g WLAN. Some properties are described analytically; all events are examined via computer simulations. It is shown that the detector is able to detect an OFDM signal in the case of multipath propagation, inexact frequency synchronization and without time synchronization. The sensitivity of the detector could be decreased in the above cases. An important condition for proper value of the detector sampling interval was derived. Three types of the channels were studied and compared. Detection threshold SNR=-9 dB was found for the signal under consideration and for two-way propagation.

  11. Design of an Angle Detector for Laser Beams Based on Grating Coupling

    Directory of Open Access Journals (Sweden)

    Weidong Zhou

    2012-02-01

    Full Text Available A novel angle detector for laser beams is designed in this paper. It takes advantage of grating coupling to couple the incident light into a slab waveguide; and, the incident light’s angle can be determined by reading the outputs of light detectors within the waveguide. This device offers fast-responding on-chip detection of laser beam’s angle. Compared to techniques based on quadrant photodiodes or lateral effect photodiodes, the device in this paper has far greater detectable range (up to a few degrees, to be specific. Performance of the laser angle detector in this paper is demonstrated by finite-difference-time-domain simulations. Numerical results show that, the detectable angle range can be adjusted by several design parameters and can reach [−4°, 4°]. The laser beam angle detector in this paper is expected to find various applications such as ultra-fast optical interconnects.

  12. Optimization of a bolometer detector for ITER based on Pt absorber on SiN membrane.

    Science.gov (United States)

    Meister, H; Eich, T; Endstrasser, N; Giannone, L; Kannamüller, M; Kling, A; Koll, J; Trautmann, T; Detemple, P; Schmitt, S

    2010-10-01

    Any plasma diagnostic in ITER must be able to operate at temperatures in excess of 200 °C and neutron loads corresponding to 0.1 dpa over its lifetime. To achieve this aim for the bolometer diagnostic, a miniaturized metal resistor bolometer detector based on Pt absorbers galvanically deposited on SiN membranes is being developed. The first two generations of detectors featured up to 4.5 μm thick absorbers. Results from laboratory tests are presented characterizing the dependence of their calibration constants under thermal loads up to 450 °C. Several detectors have been tested in ASDEX Upgrade providing reliable data but also pointing out the need for further optimization. A laser trimming procedure has been implemented to reduce the mismatch in meander resistances below 1% for one detector and the thermal drifts from this mismatch. PMID:21061487

  13. Optimization of a bolometer detector for ITER based on Pt absorber on SiN membrane

    International Nuclear Information System (INIS)

    Any plasma diagnostic in ITER must be able to operate at temperatures in excess of 200 deg. C and neutron loads corresponding to 0.1 dpa over its lifetime. To achieve this aim for the bolometer diagnostic, a miniaturized metal resistor bolometer detector based on Pt absorbers galvanically deposited on SiN membranes is being developed. The first two generations of detectors featured up to 4.5 μm thick absorbers. Results from laboratory tests are presented characterizing the dependence of their calibration constants under thermal loads up to 450 deg. C. Several detectors have been tested in ASDEX Upgrade providing reliable data but also pointing out the need for further optimization. A laser trimming procedure has been implemented to reduce the mismatch in meander resistances below 1% for one detector and the thermal drifts from this mismatch.

  14. GaN-Based Detector Enabling Technology for Next Generation Ultraviolet Planetary Missions

    Science.gov (United States)

    Aslam, S.; Gronoff, G.; Hewagama, T.; Janz, S.; Kotecki, C.

    2012-01-01

    The ternary alloy AlN-GaN-InN system provides several distinct advantages for the development of UV detectors for future planetary missions. First, (InN), (GaN) and (AlN) have direct bandgaps 0.8, 3.4 and 6.2 eV, respectively, with corresponding wavelength cutoffs of 1550 nm, 365 nm and 200 nm. Since they are miscible with each other, these nitrides form complete series of indium gallium nitride (In(sub l-x)Ga(sub x)N) and aluminum gallium nitride (Al(sub l-x)Ga(sub x)N) alloys thus allowing the development of detectors with a wavelength cut-off anywhere in this range. For the 2S0-365 nm spectral wavelength range AlGaN detectors can be designed to give a 1000x solar radiation rejection at cut-off wavelength of 325 nm, than can be achieved with Si based detectors. For tailored wavelength cut-offs in the 365-4S0 nm range, InGaN based detectors can be fabricated, which still give 20-40x better solar radiation rejection than Si based detectors. This reduced need for blocking filters greatly increases the Detective Quantum efficiency (DQE) and simplifies the instrument's optical systems. Second, the wide direct bandgap reduces the thermally generated dark current to levels allowing many observations to be performed at room temperature. Third, compared to narrow bandgap materials, wide bandgap semiconductors are significantly more radiation tolerant. Finally, with the use of an (AI, In)GaN array, the overall system cost is reduced by eliminating stringent Si CCD cooling systems. Compared to silicon, GaN based detectors have superior QE based on a direct bandgap and longer absorption lengths in the UV.

  15. Infrasound array criteria for automatic detection and front velocity estimation of snow avalanches: towards a real-time early-warning system

    Directory of Open Access Journals (Sweden)

    E. Marchetti

    2015-04-01

    Full Text Available Avalanche risk management is strongly related to the ability to identify and timely report the occurrence of snow avalanches. Infrasound has been applied to avalanche research and monitoring for the last 20 years but it never turned into an operational tool for the ambiguity to identify clear signals related to avalanches. We present here a new method based on the analysis of infrasound signals recorded by a small aperture array in Ischgl (Austria, which overcome now this limit. The method is based on array derived wave parameters, such as back-azimuth and apparent velocity. The method defines threshold criteria for automatic avalanche identification considering avalanches as a moving source of infrasound. We validate efficiency of the automatic infrasound detection with continuous observations with Doppler Radar and we show how dynamics parameters such as the velocity of a snow avalanche in any given path around the array can be efficiently derived. Our results indicate that a proper infrasound array analysis allows a robust, real-time, remote detection of snow avalanches that could thus contribute significantly to avalanche forecast and risk management.

  16. Solid-state neutron detectors based on thickness scalable hexagonal boron nitride

    CERN Document Server

    Ahmed, Kawser; Weltz, Adam; Lu, James J -Q; Danon, Yaron; Bhat, Ishwara B

    2016-01-01

    This paper reports on the device processing and characterization of hexagonal boron nitride (hBN) based solid-state thermal neutron detectors, where hBN thickness varied from 2.5 to 15 microns. These natural hBN epilayers (with 19.9% B-10) were grown by a low pressure chemical vapor deposition process. Complete dry processing was adopted for the fabrication of these metal-semiconductor-metal (MSM) configuration detectors. These detectors showed intrinsic thermal neutron detection efficiency values of 0.86%, 2.4%, 3.15%, and 4.71% for natural hBN thickness values of 2.5, 7.5, 10, and 15 microns, respectively. Measured efficiencies are very close (more than 92%) to the theoretical maximum efficiencies for corresponding hBN thickness values for these detectors. This clearly shows the hBN thickness scalability of these detectors. A 15-micron thick hBN based MSM detector is expected to yield an efficiency of 21.4%, if enriched hBN (with ~100% B-10) is used instead of natural hBN. These results demonstrate that the...

  17. FPGA Based Data Read-Out System of the Belle 2 Pixel Detector

    CERN Document Server

    Levit, Dmytro; Greenwald, Daniel; Paul, Stephan

    2014-01-01

    The upgrades of the Belle experiment and the KEKB accelerator aim to increase the data set of the experiment by the factor 50. This will be achieved by increasing the luminosity of the accelerator which requires a significant upgrade of the detector. A new pixel detector based on DEPFET technology will be installed to handle the increased reaction rate and provide better vertex resolution. One of the features of the DEPFET detector is a long integration time of 20 {\\mu}s, which increases detector occupancy up to 3 %. The detector will generate about 2 GB/s of data. An FPGA-based two-level read-out system, the Data Handling Hybrid, was developed for the Belle 2 pixel detector. The system consists of 40 read-out and 8 controller modules. All modules are built in {\\mu}TCA form factor using Xilinx Virtex-6 FPGA and can utilize up to 4 GB DDR3 RAM. The system was successfully tested in the beam test at DESY in January 2014. The functionality and the architecture of the Belle 2 Data Handling Hybrid system as well a...

  18. Multiplexed readout demonstration of a TES-based detector array in a resistance locked loop

    CERN Document Server

    van der Kuur, Jan; Kiviranta, Mikko; Akamatsu, Hiroki; Khosropanah, Pourya; Hartog, Roland den; Suzuki, Toyoaki; Jackson, Brian

    2015-01-01

    TES-based bolometer and microcalorimeter arrays with thousands of pixels are under development for several space-based and ground-based applications. A linear detector response and low levels of cross talk facilitate the calibration of the instruments. In an effort to improve the properties of TES-based detectors, fixing the TES resistance in a resistance-locked loop (RLL) under optical loading has recently been proposed. Earlier theoretical work on this mode of operation has shown that the detector speed, linearity and dynamic range should improve with respect to voltage biased operation. This paper presents an experimental demonstration of multiplexed readout in this mode of operation in a TES-based detector array with noise equivalent power values (NEP) of $3.5\\cdot 10^{-19} $W/$\\sqrt{\\mathrm{Hz}}$. The measured noise and dynamic properties of the detector in the RLL will be compared with the earlier modelling work. Furthermore, the practical implementation routes for future FDM systems for the readout of ...

  19. Rock avalanches: significance and progress (Invited)

    Science.gov (United States)

    Davies, T. R.

    2013-12-01

    1. The probability distribution of landslide volumes follows a power-law indicating that large rock avalanches dominate the terrestrial sediment supply from mountains, and that their source area morphologies dominate mountain topography. 2. Large rock slope failures (~ 106 m3 or greater) often mobilise into rock avalanches, which can travel extraordinarily long distances with devastating effect. This hypermobility has been the subject of many investigations; we have demonstrated that it can be explained quantitatively and accurately by considering the energetics of the intense rock fragmentation that always occurs during motion of a large rock mass. 3. Study of rock avalanche debris psd shows that the energy used in creating new rock surface area during fragmentation is not lost to surface energy, but is recycled generating a high-frequency elastic energy field that reduces the frictional resistance to motion during runout. 4. Rock avalanches that deposit on glaciers can eventually form large terminal moraines that have no connection with any climatic event; unless these are identified as rock-avalanche-influenced they can confuse palaeoclimatic inferences drawn from moraine ages. Rock-avalanche-derived fines, however, can be identified in moraine debris up to ten thousand years old by the characteristic micron-scale agglomerates that form during intense fragmentation, and which are absent from purely climatically-induced moraines; there is thus a strong case for re-examining existing palaeoclimatic databases to eliminate potentially rock-avalanche-influenced moraine ages. 5. Rock avalanches (especially coseismic ones) are a serious hazard, being very destructive in their own right; they also block river valleys, forming landslide dams and potentially devastating dambreak floods, and subsequent severe decade-scale aggradation of downstream fans and floodplains. Rock avalanches falling into lakes or fiords can cause catastrophic tsunami that pose a serious risk to

  20. The imaging pin detector - a simple and effective new imaging device for soft x-rays and soft beta emissions

    International Nuclear Information System (INIS)

    The development of a new bidimensional imaging detector system for soft X and beta radiations is reported. Based on the detection of the differential induction signals on pickup electrodes placed around a point anode in a gas avalanche detector, the system described has achieved a spatial resolution of better than 1mm fwhm over a field of 30mm diameter while preserving excellent pulse height resolution. The present device offers considerable potential as a cheap and robust imaging system for applications in X-ray diffraction and autoradiography. (author)

  1. A Scale Invariant Interest Point Detector in Gabor Based Energy Space

    Institute of Scientific and Technical Information of China (English)

    CAO Zheng-Cai; MA Feng-Le; FU Yi-Li; ZHANG Jian

    2014-01-01

    Interest point detection is a fundamental issue in many intermediate level vision problems and plays a significant role in vision systems. The previous interest point detectors are designed to detect some special image structures such as corners, junctions, line terminations and so on. These detectors based on some simplified 2D feature models will not work for image fea-tures that differ significantly from the models. In this paper, a scale invariant interest point detector, which is appropriate for most types of image features, is proposed based on an iterative method in the Gabor based energy space. It detects interest points by noting that there are some similarities in the phase domain for all types of image features, which are obtained by different detectors respectively. Firstly, this approach obtains the positions of candidate points by detecting the local maxima of a series of energy maps constructed by Gabor filter responses. Secondly, an iterative algorithm is adopted to select the corre-sponding characteristic scales and accurately locate the interest points simultaneously in the Gabor based energy space. Finally, in order to improve the real-time performance of the approach, a fast implementation of Gabor function is used to accelerate the process of energy space construction. Experiments show that this approach has a broader applicability than the other detec-tors and has a good performance under rotation and some other image changes.

  2. Improved X-ray detection and particle identification with avalanche photodiodes

    CERN Document Server

    Diepold, Marc; Machado, Jorge; Amaro, Pedro; Abdou-Ahmed, Marwan; Amaro, Fernando D; Antognini, Aldo; Biraben, François; Chen, Tzu-Ling; Covita, Daniel S; Dax, Andreas J; Franke, Beatrice; Galtier, Sandrine; Gouvea, Andrea L; Götzfried, Johannes; Graf, Thomas; Hänsch, Theodor W; Hildebrandt, Malte; Indelicato, Paul; Julien, Lucile; Kirch, Klaus; Knecht, Andreas; Kottmann, Franz; Krauth, Julian J; Liu, Yi-Wei; Monteiro, Cristina M B; Mulhauser, Françoise; Naar, Boris; Nebel, Tobias; Nez, François; Santos, José Paulo; Santos, Joaquim M F dos; Schuhmann, Karsten; Szabo, Csilla I; Taqqu, David; Veloso, João F C A; Voss, Andreas; Weichelt, Birgit; Pohl, Randolf

    2015-01-01

    Avalanche photodiodes are commonly used as detectors for low energy x-rays. In this work we report on a fitting technique used to account for different detector responses resulting from photo absorption in the various APD layers. The use of this technique results in an improvement of the energy resolution at 8.2 keV by up to a factor of 2, and corrects the timing information by up to 25 ns to account for space dependent electron drift time. In addition, this waveform analysis is used for particle identification, e.g. to distinguish between x-rays and MeV electrons in our experiment.

  3. Spatial aspects of vulnerability and risk resulting from snow avalanches

    Science.gov (United States)

    Fuchs, S.; Koltermann, P.; Sokratov, S.; Seliverstov, Y.; Shnyparkov, A.

    2012-04-01

    Mountain regions provide a significant proportion of areas used for human settlements, economic purpose, and recreation. Simultaneously, due to steep vertical gradients mountain areas are prone to mass movement processes. The intersection of such processes with areas used by human action turns them into hazards. In particular in arctic regions, which show a greater susceptibility to disturbances than many landscapes, considerable efforts have been undertaken in recent decades to reduce the adverse effects of mountain hazards. The concept of risk supplemented the traditional engineering approaches of technical mitigation since the 1990s to comprehensively manage these threats, and to develop strategies for a sustainable use of these areas. The concept of risk is based on a mathematical combination of hazards and consequences, but is static over time. However, three major dynamic systems interact in the field of mountain hazard risk management: the physical environment, which includes hazardous events; the social and demographic characteristics of the communities that experience them; and the values at risk such as buildings, roads, and other components of the built environment. These dynamics have not sufficiently been taken into account so far in natural hazard risk management, in particular with respect to industrialised artic regions. Within the city of Kirovsk, Kola Peninsula, Russian Federation, these dynamics were assessed by taking snow avalanche risk as an example. The test site is exposed to multiple avalanche tracks with repeated releases during individual winter seasons, endangering the built environment and any kind of infrastructure lines. The aim was to contribute to the development of a spatial risk model for mountain regions on different temporal scales. The spatial characteristics of the long-term avalanche risk, as a result of the evolution of the built environment, was analysed on an annual as well as inter-annual level. This long-term development

  4. Development of a detector based on Silicon Drift Detectors for gamma-ray spectroscopy and imaging applications

    Science.gov (United States)

    Busca, P.; Butt, A. D.; Fiorini, C.; Marone, A.; Occhipinti, M.; Peloso, R.; Quaglia, R.; Bombelli, L.; Giacomini, G.; Piemonte, C.; Camera, F.; Giaz, A.; Million, B.; Nelms, N.; Shortt, B.

    2014-05-01

    This work deals with the development of a new gamma detector based on Silicon Drift Detectors (SDDs) to readout large LaBr3:Ce scintillators for gamma-ray spectroscopy and imaging applications. The research is supported by the European Space Agency through the Technology Research Programme (TRP) and by Istituto Nazionale di Fisica Nucleare (INFN) within the Gamma project. The SDDs, produced at Fondazione Bruno Kessler (FBK) semiconductor laboratories, are designed as monolithic arrays of 3 × 3 units, each one of an active area of 8 mm × 8 mm (overall area of 26 mm × 26 mm). The readout electronics and the architecture of the camera are briefly described and then first experimental results coupling the SDD array with a 1'' × 1'' LaBr3:Ce scintillator are reported. An energy resolution of 3% FWHM at 662 keV has been measured at -20°C, better than coupling the same scintillator with a photomultiplier tube. The same scintillator is also used to evaluate position sensitivity with a 1 mm collimated Cs-137 source. The main difficulty in determining the position of the gamma-ray interaction in the crystal is associated to the high thickness/diameter ratio of the crystal (1:1) and the use of reflectors on all lateral and top sides the crystal. This last choice enhances energy resolution but makes imaging capability more challenging because light is spread over all photodetectors. Preliminary results show that the camera is able to detect shifts in the measured signals, when the source is moved with steps of 5 mm. A modified version of the centroid method is finally implemented to evaluate the imaging capability of the system.

  5. AQUARIUS: the next generation mid-IR detector for ground-based astronomy, an update.

    Science.gov (United States)

    Ives, Derek; Finger, Gert; Jakob, Gerd; Beckmann, Udo

    2014-07-01

    ESO has already published data from a preliminary laboratory analysis on the new mid-IR detector, AQUARIUS, at the previous SPIE conference of 2012, held in Amsterdam2. This data analysis indicated that this new mid-IR Si:As IBC detector, from Raytheon Vision Systems, was an excellent astronomical detector when compared to previous generations of this detector type, specifically in terms of stability, read noise and cosmetic quality. Since that time, the detector has been deployed into the VISIR1 instrument at the VLT, with very mixed performance results, especially when used with the telescope secondary mirror, to chop between two areas of sky to do background subtraction and at the same time when many frames are co-added to improve the signal to noise performance. This is the typical mode of operation for a mid-IR instrument on a ground based telescope. Preliminary astronomical data analysis indicated that the new detector was a factor of two to three times less sensitive in terms of its signal to noise per unit time performance when directly compared to the old DRS detector that AQUARIUS was designed to replace. To determine the reason for this loss of sensitivity, the instrument was removed from the telescope and not offered to the ESO user community. A detector testing campaign was then initiated in our laboratory to determine the reasons for this loss of sensitivity, assuming that it was an issue with the new detector itself. This paper reports on our latest laboratory measurements to determine the reasons for this loss of sensitivity. We specifically report on indirect measurements made to measure the quantum efficiency of the detector, which can be difficult to measure directly. We also report on a little known source of noise, called Excess Low Frequency Noise (ELFN). Detailed analysis and testing has confirmed that this ELFN is the reason for the loss of instrument sensitivity. This has been proven by a re-commissioning phase at the telescope with the

  6. Study on the performance of ZnO nanomaterial-based surface acoustic wave ultraviolet detectors

    International Nuclear Information System (INIS)

    A ZnO nanomaterial-based surface acoustic wave (SAW) ultraviolet (UV) detector is highly desirable for UV radiation detection due to its high sensitivity. In this work, firstly the ZnO nanomaterial-based SAW UV detectors operating at three different frequencies (∼50, ∼100 and ∼200 MHz) were fabricated. Then, four ZnO nanomaterial sensing layers with different thicknesses were synthesized on the SAW UV detectors operating at ∼200 MHz. The morphology, crystallization and photoluminescence of ZnO nanomaterial sensing layers were characterized using the scanning electron microscopy, transmission electron microscopy, x-ray diffraction and fluorescence spectrometer, respectively. The SAW UV detectors based on different operating frequencies and ZnO nanomaterial sensing layer's thicknesses were exposed under UV illumination at a wavelength of 365 nm and their UV responses were measured. The experimental results indicate that the frequency shift of ZnO nanomaterial-based SAW UV detector can be significantly improved by increasing operating frequency or ZnO nanomaterial sensing layer's thickness. Furthermore, the detectors exhibit good selectivity of UV illumination, an ultrahigh UV sensitivity of about 9.6 ppm (µW cm−2)−1 and fast transient properties. The experimental results agree well with the acousto-electric effect theory. What deserves to be noted is that, under a UV intensity of 150 µW cm−2, the frequency shift of the SAW UV detector operating at ∼50 MHz with a thin ZnO nanomaterial sensing layer was only ∼50 kHz while that of the SAW UV detector operating at ∼200 MHz with a thick ZnO nanomaterial sensing layer could reach ∼292 kHz. These results suggest the huge potential applications of ultra-sensitive ZnO nanomaterial-based SAW UV detectors for remote wireless UV and radiation monitoring. (paper)

  7. DDG4 A Simulation Framework based on the DD4hep Detector Description Toolkit

    Science.gov (United States)

    Frank, M.; Gaede, F.; Nikiforou, N.; Petric, M.; Sailer, A.

    2015-12-01

    The detector description is an essential component that has to be used to analyse and simulate data resulting from particle collisions in high energy physics experiments. Based on the DD4hep detector description toolkit a flexible and data driven simulation framework was designed using the Geant4 tool-kit. We present this framework and describe the guiding requirements and the architectural design, which was strongly driven by ease of use. The goal was, given an existing detector description, to simulate the detector response to particle collisions in high energy physics experiments with minimal effort, but not impose restrictions to support enhanced or improved behaviour. Starting from the ROOT based geometry implementation used by DD4hep an automatic conversion mechanism to Geant4 was developed. The physics response and the mechanism to input particle data from generators was highly formalized and can be instantiated on demand using known factory patterns. A palette of components to model the detector response is provided by default, but improved or more sophisticated components may easily be added using the factory pattern. Only the final configuration of the instantiated components has to be provided by end-users using either C++ or python scripting or an XML based description.

  8. Maximal avalanches in the Bak-Sneppen model

    OpenAIRE

    Gillett, Alexis; Meester, Ronald; van der Wal, Peter

    2006-01-01

    We study the durations of the avalanches in the maximal avalanche decomposition of the Bak-Sneppen evolution model. We show that all the avalanches in this maximal decomposition have infinite expectation, but only `barely', in the sense that if we made the appropriate threshold a tiny amount smaller (in a certain sense), then the avalanches would have finite expectation. The first of these results is somewhat surprising, since simulations suggest finite expectations.

  9. The laser calibration system for the STACEE ground-based gamma ray detector

    CERN Document Server

    Hanna, D

    2002-01-01

    We describe the design and performance of the laser system used for calibration monitoring of components of the STACEE detector. STACEE is a ground based gamma ray detector which uses the heliostats of a solar power facility to collect and focus Cherenkov light onto a system of secondary optics and photomultiplier tubes. To monitor the gain and check the linearity and timing properties of the phototubes and associated electronics, a system based on a dye laser, neutral density filters and optical fibres has been developed. In this paper we describe the system and present some results from initial tests made with it.

  10. Simulation of a flowing snow avalanche using molecular dynamics

    OpenAIRE

    Güçer, Denizhan; ÖZGÜÇ, Halil Bülent

    2014-01-01

    This paper presents an approach for the modeling and simulation of a flowing snow avalanche, which is formed of dry and liquefied snow that slides down a slope, using molecular dynamics and the discrete element method. A particle system is utilized as a base method for the simulation and marching cubes with real-time shaders are employed for rendering. A uniform grid-based neighbor search algorithm is used for collision detection for interparticle and particle-terrain interactions. A mass-spr...

  11. Relating rock avalanche morphology to emplacement processes

    Science.gov (United States)

    Dufresne, Anja; Prager, Christoph; Bösmeier, Annette

    2015-04-01

    The morphology, structure and sedimentological characteristics of rock avalanche deposits reflect both internal emplacement processes and external influences, such as runout path characteristics. The latter is mainly predisposed by topography, substrate types, and hydrogeological conditions. Additionally, the geological setting at the source slope controls, e.g. the spatial distribution of accumulated lithologies and hence material property-related changes in morphology, or the maximum clast size and amount of fines of different lithological units. The Holocene Tschirgant rock avalanche (Tyrol, Austria) resulted from failure of an intensely deformed carbonate rock mass on the southeast face of a 2,370-m-high mountain ridge. The initially sliding rock mass rapidly fragmented as it moved towards the floor of the Inn River valley. Part of the 200-250 x 106 m3 (Patzelt 2012) rock avalanche debris collided with and moved around an opposing bedrock ridge and flowed into the Ötz valley, reaching up to 6.3 km from source. Where the Tschirgant rock avalanche spread freely it formed longitudinal ridges aligned along motion direction as well as smaller hummocks. Encountering high topography, it left runup ridges, fallback patterns (i.e. secondary collapse), and compressional morphology (successively elevated, transverse ridges). Further evidence for the mechanical landslide behaviour is given by large volumes of mobilized valley-fill sediments (polymict gravels and sands). These sediments indicate both shearing and compressional faulting within the rock avalanche mass (forming their own morphological units through, e.g. in situ bulldozing or as distinctly different hummocky terrain), but also indicate extension of the spreading landslide mass (i.e. intercalated/injected gravels encountered mainly in morphological depressions between hummocks). Further influences on its morphology are given by the different lithological units. E.g. the transition from massive dolomite

  12. Performance evaluation of a lossy transmission lines based diode detector at cryogenic temperature

    Science.gov (United States)

    Villa, E.; Aja, B.; de la Fuente, L.; Artal, E.

    2016-01-01

    This work is focused on the design, fabrication, and performance analysis of a square-law Schottky diode detector based on lossy transmission lines working under cryogenic temperature (15 K). The design analysis of a microwave detector, based on a planar gallium-arsenide low effective Schottky barrier height diode, is reported, which is aimed for achieving large input return loss as well as flat sensitivity versus frequency. The designed circuit demonstrates good sensitivity, as well as a good return loss in a wide bandwidth at Ka-band, at both room (300 K) and cryogenic (15 K) temperatures. A good sensitivity of 1000 mV/mW and input return loss better than 12 dB have been achieved when it works as a zero-bias Schottky diode detector at room temperature, increasing the sensitivity up to a minimum of 2200 mV/mW, with the need of a DC bias current, at cryogenic temperature.

  13. Low-dose performance of wafer-scale CMOS-based X-ray detectors

    Science.gov (United States)

    Maes, Willem H.; Peters, Inge M.; Smit, Chiel; Kessener, Yves; Bosiers, Jan

    2015-03-01

    Compared to published amorphous-silicon (TFT) based X-ray detectors, crystalline silicon CMOS-based active-pixel detectors exploit the benefits of low noise, high speed, on-chip integration and featuring offered by CMOS technology. This presentation focuses on the specific advantage of high image quality at very low dose levels. The measurement of very low dose performance parameters like Detective Quantum Efficiency (DQE) and Noise Equivalent Dose (NED) is a challenge by itself. Second-order effects like defect pixel behavior, temporal and quantization noise effects, dose measurement accuracy and limitation of the x-ray source settings will influence the measurements at very low dose conditions. Using an analytical model to predict the low dose behavior of a detector from parameters extracted from shot-noise limited dose levels is presented. These models can also provide input for a simulation environment for optimizing the performance of future detectors. In this paper, models for predicting NED and the DQE at very low dose are compared to measurements on different CMOS detectors. Their validity for different sensor and optical stack combinations as well as for different x-ray beam conditions was validated.

  14. Geometric optimization of a neutron detector based on a lithium glass–polymer composite

    International Nuclear Information System (INIS)

    We report on the simulation and optimization of a neutron detector based on a glass–polymer composite that achieves high gamma rejection. Lithium glass is embedded in polyvinyltoluene in three geometric forms: disks, rods, and spheres. Optimal shape, geometric configuration, and size of the lithium glass fragments are determined using Geant4 simulations. All geometrical configurations maintain an approximate 7% glass to polymer mass ratio. Results indicate a 125-mm diameter as the optimal detector size for initial prototype design achieving a 10% efficiency for the thermalization of incident fission neutrons from 252Cf. The geometrical features of a composite detector are shown to have little effect on the intrinsic neutron efficiency, but a significant effect on the gamma rejection is observed. The sphere geometry showed the best overall performance with an intrinsic neutron efficiency of approximately 6% with a gamma rejection better than 10−7 for 280-μm diameter spheres. These promising results provide a motivation for prototype composite detector development based on the simulated designs. - Highlights: • Composite polymer–lithium glass scintillation detector is simulated. • Polymer is considered to be non-scintillating in the simulation. • Three forms of lithium glass are considered: disks, rods, and spheres. • Glass shape has a small effect on neutron efficiency. • Glass shape has a significant effect on gamma rejection

  15. Development and characterization of a neutron detector based on a lithium glass–polymer composite

    International Nuclear Information System (INIS)

    We report on the fabrication and characterization of a neutron scintillation detector based on a Li-glass–polymer composite that utilizes a combination of pulse height and pulse shape discrimination (PSD) to achieve high gamma rejection. In contrast to fast neutron detection in a PSD medium, we combine two scintillating materials that do not possess inherent neutron/gamma PSD properties to achieve effective PSD/pulse height discrimination in a composite material. Unlike recoil-based fast neutron detection, neutron/gamma discrimination can be robust even at low neutron energies due to the high Q-value neutron capture on 6Li. A cylindrical detector with a 5.05 cm diameter and 5.08 cm height was fabricated from scintillating 1 mm diameter Li-glass rods and scintillating polyvinyltoluene. The intrinsic efficiency for incident fission neutrons from 252Cf and gamma rejection of the detector were measured to be 0.33% and less than 10−8, respectively. These results demonstrate the high selectivity of the detector for neutrons and provide motivation for prototyping larger detectors optimized for specific applications, such as detection and event-by-event spectrometry of neutrons produced by fission

  16. Geometric optimization of a neutron detector based on a lithium glass–polymer composite

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, M., E-mail: mike.f.mayer@gmail.com [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA 16802 (United States); Nattress, J. [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA 16802 (United States); Trivelpiece, C. [Materials Research Institute, The Pennsylvania State University, University Park, PA 16802 (United States); Jovanovic, I. [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA 16802 (United States)

    2015-06-01

    We report on the simulation and optimization of a neutron detector based on a glass–polymer composite that achieves high gamma rejection. Lithium glass is embedded in polyvinyltoluene in three geometric forms: disks, rods, and spheres. Optimal shape, geometric configuration, and size of the lithium glass fragments are determined using Geant4 simulations. All geometrical configurations maintain an approximate 7% glass to polymer mass ratio. Results indicate a 125-mm diameter as the optimal detector size for initial prototype design achieving a 10% efficiency for the thermalization of incident fission neutrons from {sup 252}Cf. The geometrical features of a composite detector are shown to have little effect on the intrinsic neutron efficiency, but a significant effect on the gamma rejection is observed. The sphere geometry showed the best overall performance with an intrinsic neutron efficiency of approximately 6% with a gamma rejection better than 10{sup −7} for 280-μm diameter spheres. These promising results provide a motivation for prototype composite detector development based on the simulated designs. - Highlights: • Composite polymer–lithium glass scintillation detector is simulated. • Polymer is considered to be non-scintillating in the simulation. • Three forms of lithium glass are considered: disks, rods, and spheres. • Glass shape has a small effect on neutron efficiency. • Glass shape has a significant effect on gamma rejection.

  17. Boron-coated straws as a replacement for 3He-based neutron detectors

    Science.gov (United States)

    Lacy, Jeffrey L.; Athanasiades, Athanasios; Sun, Liang; Martin, Christopher S.; Lyons, Tom D.; Foss, Michael A.; Haygood, Hal B.

    2011-10-01

    US and international government efforts to equip major seaports with large area neutron detectors, aimed to intercept the smuggling of nuclear materials, have precipitated a critical shortage of 3He gas. It is estimated that the annual demand of 3He for US security applications alone is more than the worldwide supply. This is strongly limiting the prospects of neutron science, safeguards, and other applications that rely heavily on 3He-based detectors. Clearly, alternate neutron detection technologies that can support large sensitive areas, and have low gamma sensitivity and low cost must be developed. We propose a low-cost technology based on long copper tubes (straws), coated on the inside with a thin layer of 10B-enriched boron carbide ( 10B 4C). In addition to the high abundance of boron on Earth and low cost of 10B enrichment, the boron-coated straw (BCS) detector offers distinct advantages over conventional 3He-based detectors, and alternate technologies such as 10BF 3 tubes and 10B-coated rigid tubes. These include better distribution inside moderator assemblies, many-times faster electronic signals, no pressurization, improved gamma-ray rejection, no toxic or flammable gases, and ease of serviceability. We present the performance of BCS detectors dispersed in a solid plastic moderator to address the need for portal monitoring. The design adopts the outer dimensions of currently deployed 3He-based monitors, but takes advantage of the small BCS diameter to achieve a more uniform distribution of neutron converter throughout the moderating material. We show that approximately 63 BCS detectors, each 205 cm long, distributed inside the moderator, can match or exceed the detection efficiency of typical monitors fitted with a 5 cm diameter 3He tube, 187 cm long, pressurized to 3 atm.

  18. Concept of a novel fast neutron imaging detector based on THGEM for fan-beam tomography applications

    OpenAIRE

    Cortesi, M.; Zboray, R.; Adams, R.; Dangendorf, V.; Prasser, H.-M.

    2012-01-01

    The conceptual design and operational principle of a novel high-efficiency, fast neutron imaging detector based on THGEM, intended for future fan-beam transmission tomography applications, is described. We report on a feasibility study based on theoretical modeling and computer simulations of a possible detector configuration prototype. In particular we discuss results regarding the optimization of detector geometry, estimation of its general performance, and expected imaging quality: it has ...

  19. Development of an angled Si-PM-based detector unit for positron emission mammography (PEM) system

    Science.gov (United States)

    Nakanishi, Kouhei; Yamamoto, Seiichi

    2016-11-01

    Positron emission mammography (PEM) systems have higher sensitivity than clinical whole body PET systems because they have a smaller ring diameter. However, the spatial resolution of PEM systems is not high enough to detect early stage breast cancer. To solve this problem, we developed a silicon photomultiplier (Si-PM) based detector unit for the development of a PEM system. Since a Si-PM's channel is small, Si-PM can resolve small scintillator pixels to improve the spatial resolution. Also Si-PM based detectors have inherently high timing resolution and are able to reduce the random coincidence events by reducing the time window. We used 1.5×1.9×15 mm LGSO scintillation pixels and arranged them in an 8×24 matrix to form scintillator blocks. Four scintillator blocks were optically coupled to Si-PM arrays with an angled light guide to form a detector unit. Since the light guide has angles of 5.625°, we can arrange 64 scintillator blocks in a nearly circular shape (a regular 64-sided polygon) using 16 detector units. We clearly resolved the pixels of the scintillator blocks in a 2-dimensional position histogram where the averages of the peak-to-valley ratios (P/Vs) were 3.7±0.3 and 5.7±0.8 in the transverse and axial directions, respectively. The average energy resolution was 14.2±2.1% full-width at half-maximum (FWHM). By including the temperature dependent gain control electronics, the photo-peak channel shifts were controlled within ±1.5% with the temperature from 23 °C to 28 °C. With these results, in addition to the potential high timing performance of Si-PM based detectors, our developed detector unit is promising for the development of a high-resolution PEM system.

  20. Characterisation of a detector based on microchannel plates for electrons in the energy range 10-20 keV

    Energy Technology Data Exchange (ETDEWEB)

    Moldovan, G. [Department of Materials, University of Oxford, Parks Road, Oxford, Oxon OX1 3PH (United Kingdom)], E-mail: grigore.moldovan@materials.ox.ac.uk; Matheson, J.; Derbyshire, G. [Rutherford Appleton Laboratory, Science and Technology Facilities Council, Chilton, Didcot, Oxon OX11 0QX (United Kingdom); Kirkland, A. [Department of Materials, University of Oxford, Parks Road, Oxford, Oxon OX1 3PH (United Kingdom)

    2008-11-11

    As part of a feasibility study into the use of novel electron detectors for an X-ray photoelectron emission microscope (XPEEM), we have characterised a detector based on microchannel plates (MCPs), a phosphor screen and a CCD camera. For XPEEM, an imaging detector is required for electrons in the energy range 10-20 keV. This type of detector is a standard fitment on commercial instruments and we have studied its performance in some detail in order to provide a baseline against which to evaluate future detector technologies. We present detective quantum efficiency (DQE), noise power spectrum (NPS) and modulation transfer function (MTF) measurements of a commercial detector, in the energy range of interest, as a function of the detector bias voltage.

  1. Characterization of thermal cross-talk in a MEMS-based thermopile detector array

    NARCIS (Netherlands)

    Wu, H.; Grabarnik, S.; Emadi, A.; De Graaf, G.; Wolffenbuttel, R.F.

    2009-01-01

    The spectral resolution of a MEMS-based IR microspectrometer critically depends on the thermal cross-talk between adjacent TE elements in the detector array. Thermal isolation between elements is realized by using bulk micromachining directly following CMOS processing. This paper reports on the char

  2. Development of a thermal neutron detector based on scintillating fibers and silicon photomultipliers

    International Nuclear Information System (INIS)

    We propose a technique for thermal neutron detection, based on a 6Li converter placed in front of scintillating fibers readout by means of silicon photomultipliers. Such a technique allows building cheap and compact detectors and dosimeters, thus possibly opening new perspectives in terms of granular monitoring of neutron fluxes as well as space-resolved neutron detection.

  3. A Low-Cost Liquid-Chromatography System Using a Spectronic 20-Based Detector.

    Science.gov (United States)

    Jezorek, John R.; And Others

    1986-01-01

    Describes the design and evaluation of a Spectronic 20-based detector as well as a simple system for postcolumn derivatization useful for metal-ion chromatographic detection. Both detection and derivatization can be performed in the ultra-violet (UV) mode using a low-cost UV-visible spectrophotometer and UV-region derivatization reagents. (JN)

  4. Evolution of Some Particle Detectors Based On the Discharge in Gases

    Science.gov (United States)

    Charpak, G.

    1969-11-19

    Summary of the properties of some of the detectors that are commonly used in counter experiments to localize charged particles, and which are based on discharge in gases under the influence of electric fields and some basic facts of gaseous amplification in homogeneous and inhomogeneous fields.

  5. A Real Valued Neural Network Based Autoregressive Energy Detector for Cognitive Radio Application.

    Science.gov (United States)

    Onumanyi, A J; Onwuka, E N; Aibinu, A M; Ugweje, O C; Salami, M J E

    2014-01-01

    A real valued neural network (RVNN) based energy detector (ED) is proposed and analyzed for cognitive radio (CR) application. This was developed using a known two-layered RVNN model to estimate the model coefficients of an autoregressive (AR) system. By using appropriate modules and a well-designed detector, the power spectral density (PSD) of the AR system transfer function was estimated and subsequent receiver operating characteristic (ROC) curves of the detector generated and analyzed. A high detection performance with low false alarm rate was observed for varying signal to noise ratio (SNR), sample number, and model order conditions. The proposed RVNN based ED was then compared to the simple periodogram (SP), Welch periodogram (WP), multitaper (MT), Yule-Walker (YW), Burg (BG), and covariance (CV) based ED techniques. The proposed detector showed better performance than the SP, WP, and MT while providing better false alarm performance than the YW, BG, and CV. Data provided here support the effectiveness of the proposed RVNN based ED for CR application.

  6. Nano-multiplication region avalanche photodiodes and arrays

    Science.gov (United States)

    Zheng, Xinyu (Inventor); Pain, Bedabrata (Inventor); Cunningham, Thomas J. (Inventor)

    2011-01-01

    An avalanche photodiode with a nano-scale reach-through structure comprising n-doped and p-doped regions, formed on a silicon island on an insulator, so that the avalanche photodiode may be electrically isolated from other circuitry on other silicon islands on the same silicon chip as the avalanche photodiode. For some embodiments, multiplied holes generated by an avalanche reduces the electric field in the depletion region of the n-doped and p-doped regions to bring about self-quenching of the avalanche photodiode. Other embodiments are described and claimed.

  7. Modeling of radiation damage recovery in particle detectors based on GaN

    Science.gov (United States)

    Gaubas, E.; Ceponis, T.; Pavlov, J.

    2015-12-01

    The pulsed characteristics of the capacitor-type and PIN diode type detectors based on GaN have been simulated using the dynamic and drift-diffusion models. The drift-diffusion current simulations have been implemented by employing the commercial software package Synopsys TCAD Sentaurus. The bipolar drift regime has been analyzed. The possible internal gain in charge collection through carrier multiplication processes determined by impact ionization has been considered in order to compensate carrier lifetime reduction due to radiation defects introduced into GaN material of detector.

  8. Characterization of thermal cross-talk in a MEMS-based thermopile detector array

    OpenAIRE

    H. Wu; Grabarnik, S.; Emadi, A.; De Graaf, G.; Wolffenbuttel, R F

    2009-01-01

    The spectral resolution of a MEMS-based IR microspectrometer critically depends on the thermal cross-talk between adjacent TE elements in the detector array. Thermal isolation between elements is realized by using bulk micromachining directly following CMOS processing. This paper reports on the characterization results of bridge-shaped TE detector elements that are cut out of a membrane. Elements with dimensions of 650 × 36 μm2 are separated by 10 μm wide gaps in order to minimize the thermal...

  9. A Leakage Current-based Measurement of the Radiation Damage in the ATLAS Pixel Detector

    CERN Document Server

    Gorelov, Igor; The ATLAS collaboration

    2015-01-01

    A measurement has been made of the radiation damage incurred by the ATLAS Pixel Detector barrel silicon modules from the beginning of operations through the end of 2012. This translates to hadronic fluence received over the full period of operation at energies up to and including 8 TeV. The measurement is based on a per-module measurement of the silicon sensor leakage current. The results are presented as a function of integrated luminosity and compared to predictions by the Hamburg Model. This information can be used to predict limits on the lifetime of the Pixel Detector due to current, for various operating scenarios.

  10. Neutron imaging detector based on the muPIC micro-pixel chamber

    OpenAIRE

    Parker, J. D.; Hattori, K.; Fujioka, H.; Harada, M; Iwaki, S.; Kabuki, S.; Kishimoto, Y.; Kubo, H.; Kurosawa, S.; Miuchi, K; Nagae, T.; Nishimura, H; Oku, T; SAWANO, T.; Shinohara, T

    2012-01-01

    We have developed a prototype time-resolved neutron imaging detector employing the micro-pixel chamber (muPIC), a micro-pattern gaseous detector, coupled with a field programmable gate array-based data acquisition system for applications in neutron radiography at high-intensity neutron sources. The prototype system, with an active area of 10cm x 10cm and operated at a gas pressure of 2 atm, measures both the energy deposition (via time-over-threshold) and 3-dimensional track of each neutron-i...

  11. PoGOLino: A scintillator-based balloon-borne neutron detector

    Energy Technology Data Exchange (ETDEWEB)

    Kole, Merlin, E-mail: merlin@particle.kth.se [KTH Royal Institute of Technology, Department of Physics, 106 91 Stockholm (Sweden); The Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Centre, 106 91 Stockholm (Sweden); Chauvin, Maxime [KTH Royal Institute of Technology, Department of Physics, 106 91 Stockholm (Sweden); The Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Centre, 106 91 Stockholm (Sweden); Fukazawa, Yasushi [Department of Physical Science, Hiroshima University, Hiroshima 739-8526 (Japan); Fukuda, Kentaro; Ishizu, Sumito [Tokuyama Corporation, Shunan, Yamaguchi (Japan); Jackson, Miranda [KTH Royal Institute of Technology, Department of Physics, 106 91 Stockholm (Sweden); The Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Centre, 106 91 Stockholm (Sweden); Kamae, Tune [University of Tokyo, Department of Physics, 113-0033 Tokyo (Japan); Kawaguchi, Noriaki [Tokuyama Corporation, Shunan, Yamaguchi (Japan); Kawano, Takafumi [Department of Physical Science, Hiroshima University, Hiroshima 739-8526 (Japan); Kiss, Mózsi; Moretti, Elena; Pearce, Mark; Rydström, Stefan [KTH Royal Institute of Technology, Department of Physics, 106 91 Stockholm (Sweden); The Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Centre, 106 91 Stockholm (Sweden); Takahashi, Hiromitsu [Department of Physical Science, Hiroshima University, Hiroshima 739-8526 (Japan); Yanagida, Takayuki [Kyushu Institute of Technology, Kitakyushu, Fukuoka (Japan)

    2015-01-11

    PoGOLino is a balloon-borne scintillator-based experiment developed to study the largely unexplored high altitude neutron environment at high geomagnetic latitudes. The instrument comprises two detectors that make use of LiCAF, a novel neutron sensitive scintillator, sandwiched by BGO crystals for background reduction. The experiment was launched on March 20th 2013 from the Esrange Space Centre, Northern Sweden (geomagnetic latitude of 65°), for a three hour flight during which the instrument took data up to an altitude of 30.9 km. The detector design and ground calibration results are presented together with the measurement results from the balloon flight.

  12. PoGOLino: a scintillator-based balloon-borne neutron detector

    CERN Document Server

    Kole, Merlin; Fukazawa, Yasushi; Fukuda, Kentaro; Ishizu, Sumito; Jackson, Miranda; Kamae, Tune; Kawaguchi, Noriaki; Kawano, Takafumi; Kiss, Mozsi; Moretti, Elena; Pearce, Mark; Rydström, Stefan; Takahashi, Hiromitsu; Yanagida, Takayuki

    2014-01-01

    PoGOLino is a balloon-borne scintillator-based experiment developed to study the largely unexplored high altitude neutron environment at high geomagnetic latitudes. The instrument comprises two detectors that make use of LiCAF, a novel neutron sensitive scintillator, sandwiched by BGO crystals for background reduction. The experiment was launched on March 20th 2013 from the Esrange Space Centre, Northern Sweden (geomagnetic latitude of $65^\\circ$), for a three hour flight during which the instrument took data up to an altitude of 30.9 km. The detector design and ground calibration results are presented together with the measurement results from the balloon flight.

  13. A transputer-based list mode parallel system for digital radiography with 2D silicon detectors

    International Nuclear Information System (INIS)

    The authors believe that a dedicated parallel computer system can represent an effective and flexible approach to the problem of list mode acquisition and reconstruction of digital radiographic images obtained with a double-sided silicon microstrip detector. They present a Transputer-based implementation of a parallel system for the data acquisition and image reconstruction from a silicon crystal with 200μm read-out pitch. They are currently developing a prototype of the system connected to a detector with a 10mm2 sensitive area

  14. MCP-based detector in the Magnetic Field: Some results and perspectives

    CERN Document Server

    Patarakin, O O; CERN. Geneva; Kartamushev, A A; Tikhonov, V N

    1997-01-01

    This paper presents the experimental results of the MCP-based detector timing resolution studying. The timing resolution of shevron-type MCP-detector was obtained =82±2 ps as without magnetic field as with longitudinal magnetic field at 1.5 kG. It was shown that a deterioration of a timing resolution in this field is smaller than 20 ps. The timing resolution =31±2 ps had been obtained for thin (10%) amplitude spectrum

  15. Demonstrating a directional detector based on neon for characterizing high energy neutrons

    OpenAIRE

    Hexley, A.; Moulai, M. H.; Spitz, J.; Conrad, J. M.

    2015-01-01

    MITPC is a gas-based time projection chamber used for detecting fast, MeV-scale neutrons. The standard version of the detector relies on a mixture of 600~torr gas composed of 87.5% $^4$He and 12.5% CF$_4$ for precisely measuring the energy and direction of neutron-induced nuclear recoils. We describe studies performed with a prototype detector investigating the use of Ne, as a replacement for $^4$He, in the gas mixture. Our discussion focuses on the advantages of Ne as the fast neutron target...

  16. Avalanche Hazard Mapping with Satellite Data and a Digital Elevation Model

    Directory of Open Access Journals (Sweden)

    Urs Gruber

    1995-04-01

    Full Text Available Today avalanche hazard mapping is a very time-consuming affair. To map large remote areas, a method based on satellite imagery and digital elevation model has been developed. For this purpose, two test-sites in the Swiss Apls were selected. To simulate the avalanche hazard, the existing Salm-Voellmy model was modified to the computer environment and extended to the characteristics of avalanches within forested terrain. The forests were classified with Landsat-TM data. So far, only a single forest-class was established. The separation of forest, shrub, and non-forested area along the timberline poses a problem. On the other hand, a classification of small openings and avalanche tracks within the forest could be achieved. A comparison with the existing avalanche cadastral map revealed that 85 per cent of the risk areas were correctly classified. On the other hand, the separation into the defined red and blue danger zones was not satisfactory. For the model's application to become operational, further improvements are needed. However, the general approach is very promising, and should lead to more reliable hazard maps for planning purposes, as well as to new and better insights into the mutual effects between snow and forest.

  17. Improvement of an X-ray imaging detector based on a scintillating guides screen

    CERN Document Server

    Badel, X; Linnros, J; Kleimann, P; Froejdh, C; Petersson, C S

    2002-01-01

    An X-ray imaging detector has been developed for dental applications. The principle of this detector is based on application of a silicon charge coupled device covered by a scintillating wave-guide screen. Previous studies of such a detector showed promising results concerning the spatial resolution but low performance in terms of signal to noise ratio (SNR) and sensitivity. Recent results confirm the wave-guiding properties of the matrix and show improvement of the detector in terms of response uniformity, sensitivity and SNR. The present study is focussed on the fabrication of the scintillating screen where the principal idea is to fill a matrix of Si pores with a CsI scintillator. The photoluminescence technique was used to prove the wave-guiding property of the matrix and to inspect the filling uniformity of the pores. The final detector was characterized by X-ray evaluation in terms of spatial resolution, light output and SNR. A sensor with a spatial resolution of 9 LP/mm and a SNR over 50 has been achie...

  18. Development of High-Resolution Muon Tracking Systems Based on Micropattern Detectors

    CERN Document Server

    Bortfeldt, Jonathan; Heereman, David; Hertenberger, Ralf

    2012-01-01

    A muon tracking system consisting of four 9cm x 10cm sized bulk Micromegas detectors with 128um amplification-gap and two 10cm x 10cm triple GEM detectors is foreseen for high-precision tracking of 140GeV muons at the H8 beamline at CERN with a rate of up to 10kHz and an overall resolution below 40um. Larger detectors with an active area of 0.5m^2 and more are under development for detector studies in high neutron or gamma ray background environments at the Gamma Irradiation Facility at CERN and the Munich tandem accelerator. Signal studies of both detector types have been performed by recording cosmic muon and 5.9keV X-ray signals with a single charge-sensitive preamplifier using several gas-mixtures of Ar:CO_2. The signals were digitized using 1GHz VME based flashADCs with 2520 sampling points. The analysis of the complete signal-cycles allows for the determination of rise times, pulse heights, timing fluctuations and discrimination of background, resulting in a FWHM energy resolution of about 20% and detec...

  19. ROOT based Offline and Online Analysis (ROAn): An analysis framework for X-ray detector data

    International Nuclear Information System (INIS)

    The ROOT based Offline and Online Analysis (ROAn) framework was developed to perform data analysis on data from Depleted P-channel Field Effect Transistor (DePFET) detectors, a type of active pixel sensors developed at the MPI Halbleiterlabor (HLL). ROAn is highly flexible and extensible, thanks to ROOT's features like run-time type information and reflection. ROAn provides an analysis program which allows to perform configurable step-by-step analysis on arbitrary data, an associated suite of algorithms focused on DePFET data analysis, and a viewer program for displaying and processing online or offline detector data streams. The analysis program encapsulates the applied algorithms in objects called steps which produce analysis results. The dependency between results and thus the order of calculation is resolved automatically by the program. To optimize algorithms for studying detector effects, analysis parameters are often changed. Such changes of input parameters are detected in subsequent analysis runs and only the necessary recalculations are triggered. This saves time and simultaneously keeps the results consistent. The viewer program offers a configurable Graphical User Interface (GUI) and process chain, which allows the user to adapt the program to different tasks such as offline viewing of file data, online monitoring of running detector systems, or performing online data analysis (histogramming, calibration, etc.). Because of its modular design, ROAn can be extended easily, e.g. be adapted to new detector types and analysis processes

  20. ROOT based Offline and Online Analysis (ROAn): An analysis framework for X-ray detector data

    Science.gov (United States)

    Lauf, Thomas; Andritschke, Robert

    2014-10-01

    The ROOT based Offline and Online Analysis (ROAn) framework was developed to perform data analysis on data from Depleted P-channel Field Effect Transistor (DePFET) detectors, a type of active pixel sensors developed at the MPI Halbleiterlabor (HLL). ROAn is highly flexible and extensible, thanks to ROOT's features like run-time type information and reflection. ROAn provides an analysis program which allows to perform configurable step-by-step analysis on arbitrary data, an associated suite of algorithms focused on DePFET data analysis, and a viewer program for displaying and processing online or offline detector data streams. The analysis program encapsulates the applied algorithms in objects called steps which produce analysis results. The dependency between results and thus the order of calculation is resolved automatically by the program. To optimize algorithms for studying detector effects, analysis parameters are often changed. Such changes of input parameters are detected in subsequent analysis runs and only the necessary recalculations are triggered. This saves time and simultaneously keeps the results consistent. The viewer program offers a configurable Graphical User Interface (GUI) and process chain, which allows the user to adapt the program to different tasks such as offline viewing of file data, online monitoring of running detector systems, or performing online data analysis (histogramming, calibration, etc.). Because of its modular design, ROAn can be extended easily, e.g. be adapted to new detector types and analysis processes.

  1. Feasibility of Amorphous Selenium Based Photon Counting Detectors for Digital Breast Tomosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Chen, J.; O' Connor, P.; Lehnert, J., De Geronimo, G., Dolazza, E., Tousignant, O., Laperriere, L., Greenspan, J., Zhao, W.

    2009-02-27

    Amorphous selenium (a-Se) has been incorporated successfully in direct conversion flat panel x-ray detectors, and has demonstrated superior image quality in screening mammography and digital breast tomosynthesis (DBT) under energy integration mode. The present work explores the potential of a-Se for photon counting detectors in DBT. We investigated major factors contributing to the variation in the charge collected by a pixel upon absorption of each x-ray photon. These factors included x-ray photon interaction, detector geometry, charge transport, and the pulse shaping and noise properties of the photon counting readout circuit. Experimental measurements were performed on a linear array test structure constructed by evaporating an a-Se layer onto an array of 100 {mu}m pitch strip electrodes, which are connected to a 32 channel low noise photon counting integrated circuit. The measured pulse height spectrum (PHS) under polychromatic xray exposure was interpreted quantitatively using the factors identified. Based on the understanding of a-Se photon counting performance, design parameters were proposed for a 2D detector with high quantum efficiency and count rate that could meet the requirements of photon counting detector for DBT.

  2. Improvement of an X-ray imaging detector based on a scintillating guides screen

    International Nuclear Information System (INIS)

    An X-ray imaging detector has been developed for dental applications. The principle of this detector is based on application of a silicon charge coupled device covered by a scintillating wave-guide screen. Previous studies of such a detector showed promising results concerning the spatial resolution but low performance in terms of signal to noise ratio (SNR) and sensitivity. Recent results confirm the wave-guiding properties of the matrix and show improvement of the detector in terms of response uniformity, sensitivity and SNR. The present study is focussed on the fabrication of the scintillating screen where the principal idea is to fill a matrix of Si pores with a CsI scintillator. The photoluminescence technique was used to prove the wave-guiding property of the matrix and to inspect the filling uniformity of the pores. The final detector was characterized by X-ray evaluation in terms of spatial resolution, light output and SNR. A sensor with a spatial resolution of 9 LP/mm and a SNR over 50 has been achieved using a standard dental X-ray source and doses in the order of those used at the moment by dentists (around 25 mR)

  3. Measuring acoustic emissions in an avalanche slope

    Science.gov (United States)

    Reiweger, Ingrid; Schweizer, Jürg

    2014-05-01

    Measurements of acoustic emissions are a common technique for monitoring damage and predicting imminent failure of a material. Within natural hazards it has already been used to successfully predict the break-off of a hanging glacier. To explore the applicability of the acoustic emission (AE) technique for avalanche prediction, we installed two acoustic sensors (with 30 kHz and 60 kHz resonance frequency) in an avalanche prone slope at the Mittelgrat in the Parsenn ski area above Davos, Switzerland. The slope is north-east facing, frequently wind loaded, and approximately 35° steep. The AE signals - in particular the event energy and waiting time distributions - were compared with slope stability. The latter was determined by observing avalanche activity. The results of two winter's measurements yielded that the exponent β of the inverse cumulative distribution of event energy showed a significant drop (from a value of 3.5 to roughly 2.5) at very unstable conditions, i.e. on the three days during our measurement periods when spontaneous avalanches released on our study slope.

  4. Avalanches in a Bose-Einstein condensate

    OpenAIRE

    Schuster, J; A. Marte; Amtage, S; Sang, B.; Rempe, G.; Beijerinck, HCW Herman

    2001-01-01

    Collisional avalanches are identified to be responsible for an 8-fold increase of the initial loss rate of a large 87-Rb condensate. We show that the collisional opacity of an ultra-cold gas exhibits a critical value. When exceeded, losses due to inelastic collisions are substantially enhanced. Under these circumstances, reaching the hydrodynamic regime in conventional BEC experiments is highly questionable.

  5. Single photon source characterization with a superconducting single photon detector

    CERN Document Server

    Hadfield, R H; Miller, A J; Mirin, R P; Nam, S W; Schwall, R E; Stevens, M J; Gruber, Steven S.; Hadfield, Robert H.; Miller, Aaron J.; Mirin, Richard P.; Nam, Sae Woo; Schwall, Robert E.; Stevens, Martin J.

    2005-01-01

    Superconducting single photon detectors (SSPD) based on nanopatterned niobium nitride wires offer single photon counting at fast rates, low jitter, and low dark counts, from visible wavelengths well into the infrared. We demonstrate the first use of an SSPD, packaged in a commercial cryocooler, for single photon source characterization. The source is an optically pumped, microcavity-coupled InGaAs quantum dot, emitting single photons on demand at 902 nm. The SSPD replaces the second silicon Avalanche Photodiode (APD) in a Hanbury-Brown Twiss interferometer measurement of the source second-order correlation function, g (2) (tau). The detection efficiency of the superconducting detector system is >2 % (coupling losses included). The SSPD system electronics jitter is 170 ps, versus 550 ps for the APD unit, allowing the source spontaneous emission lifetime to be measured with improved resolution.

  6. Time resolution in scintillator based detectors for positron emission tomography

    International Nuclear Information System (INIS)

    In the domain of medical photon detectors L(Y)SO scintillators are used for positron emission tomography (PET). The interest for time of flight (TOF) in PET is increasing since measurements have shown that new crystals like L(Y)SO coupled to state of the art photodetectors, e.g. silicon photomultipliers (SiPM), can reach coincidence time resolutions (CTRs) of far below 500ps FWHM. To achieve these goals it is important to study the processe in the whole detection chain, i.e. the high energy particle or gamma interaction in the crystal, the scintillation process itself, the light propagation in the crystal with the light transfer to the photodetector, and the electronic readout. In this thesis time resolution measurements for a PET like system are performed in a coincidence setup utilizing the ultra fast amplifier discriminator NINO. We found that the time-over-threshold energy information provided by NINO shows a degradation in energy resolution for higher SiPM bias voltages. This is a consequence of the increasing dark count rate (DCR) of the SiPM with higher bias voltages together with the exponential decay of the signal. To overcome this problem and to operate the SiPM at its optimum voltage in terms of timing we developed a new electronic board that employs NINO only as a low noise leading edge discriminator together with an analog amplifier which delivers the energy information. With this new electronic board we indeed improved the measured CTR by about 15%. To study the limits of time resolution in more depth we measured the CTR with 2x2x3mm3 LSO:Ce codoped 0.4%Ca crystals coupled to commercially available SiPMs (Hamamatsu S10931-50P MPPC) and achieved a CTR of 108±5ps FWHM at an energy of 511keV. We determined the influence of the data acquisition system and the electronics on the CTR to be 27±2ps FWHM and thus negligible. To quantitatively understand the measured values, we developed a Monte Carlo simulation tool in MATLAB that incorporates the timing

  7. Fabrication of Gamma Detectors Based on Magnetic Ag:Er Microcalorimeters

    Energy Technology Data Exchange (ETDEWEB)

    Friedrich, Stephan [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Boyd, Stephen [Univ. of New Mexico, Albuquerque, NM (United States); Cantor, Robin [STAR Cryoelectronics, Santa Fe, NM (United States)

    2015-11-25

    This report discusses the photolithographic fabrication of ultra-high resolution gamma-ray detectors based on magnetic microcalorimeters (MMCs). The MMC uses a novel Er-doped silver sensor (Ag:Er) that is expected to have higher sensitivity than the Er-doped gold (Au:Er) sensors currently in use. The MMC also integrates the first-stage SQUID preamplifier on the same chip as the MMC gamma detector to increase its signal-to-noise ratio. In addition, the MMC uses a passive Ta-Nb heat switch to replace one of the common long-term failure points in earlier detectors. This report discusses the fabrication process we have developed to implement the proposed improvements.

  8. Fabrication of Gamma Detectors Based on Magnetic Ag:Er Microcalorimeters

    Energy Technology Data Exchange (ETDEWEB)

    Friedrich, Stephan [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Boyd, Stephen [Univ. of New Mexico, Albuquerque, NM (United States); Cantor, Robin [STAR Cryoelectronics, Santa Fe, NM (United States)

    2016-05-06

    This report discusses the photolithographic fabrication of ultra-high resolution gamma-ray detectors based on magnetic microcalorimeters (MMCs). The MMC uses a novel Er-doped silver sensor (Ag:Er) that is expected to have higher sensitivity than the Er-doped gold (Au:Er) sensors currently in use. The MMC also integrates the first-stage SQUID preamplifier on the same chip as the MMC gamma detector to increase its signal-to-noise ratio. In addition, the MMC uses a passive Ta-Nb heat switch to replace one of the common long-term failure points in earlier detectors. This report discusses the fabrication process we have developed to implement the proposed improvements.

  9. Python based integration of GEM detector electronics with JET data acquisition system

    Science.gov (United States)

    Zabołotny, Wojciech M.; Byszuk, Adrian; Chernyshova, Maryna; Cieszewski, Radosław; Czarski, Tomasz; Dalley, Simon; Hogben, Colin; Jakubowska, Katarzyna L.; Kasprowicz, Grzegorz; Poźniak, Krzysztof; Rzadkiewicz, Jacek; Scholz, Marek; Shumack, Amy

    2014-11-01

    This paper presents the system integrating the dedicated measurement and control electronic systems for Gas Electron Multiplier (GEM) detectors with the Control and Data Acquisition system (CODAS) in the JET facility in Culham, England. The presented system performs the high level procedures necessary to calibrate the GEM detector and to protect it against possible malfunctions or dangerous changes in operating conditions. The system also allows control of the GEM detectors from CODAS, setting of their parameters, checking their state, starting the plasma measurement and to reading the results. The system has been implemented using the Python language, using the advanced libraries for implementation of network communication protocols, for object based hardware management and for data processing.

  10. Demonstrating a directional detector based on neon for characterizing high energy neutrons

    CERN Document Server

    Hexley, A; Spitz, J; Conrad, J M

    2015-01-01

    MITPC is a gas-based time projection chamber used for detecting fast, MeV-scale neutrons. The standard version of the detector relies on a mixture of 600~torr gas composed of 87.5% $^4$He and 12.5% CF$_4$ for precisely measuring the energy and direction of neutron-induced nuclear recoils. We describe studies performed with a prototype detector investigating the use of Ne, as a replacement for $^4$He, in the gas mixture. Our discussion focuses on the advantages of Ne as the fast neutron target for high energy neutron events ($\\lesssim$100 MeV) and a demonstration that the mixture will be effective for this event class. We find that the achievable gain and transverse diffusion of drifting electrons in the Ne mixture are acceptable and that the detector uptime lost due to voltage breakdowns in the amplification plane is negligible, compared to $\\sim$ 20% with the $^4$He mixture.

  11. Neutron imaging detector based on the muPIC micro-pixel chamber

    CERN Document Server

    Parker, J D; Fujioka, H; Harada, M; Iwaki, S; Kabuki, S; Kishimoto, Y; Kubo, H; Kurosawa, S; Miuchi, K; Nagae, T; Nishimura, H; Oku, T; Sawano, T; Shinohara, T; Suzuki, J; Takada, A; Tanimori, T; Ueno, K

    2012-01-01

    We have developed a prototype time-resolved neutron imaging detector employing the micro-pixel chamber (muPIC), a micro-pattern gaseous detector, coupled with a field programmable gate array-based data acquisition system for applications in neutron radiography at high-intensity neutron sources. The prototype system, with an active area of 10cm x 10cm and operated at a gas pressure of 2 atm, measures both the energy deposition (via time-over-threshold) and 3-dimensional track of each neutron-induced event, allowing the reconstruction of the neutron interaction point with improved accuracy. Using a simple position reconstruction algorithm, a spatial resolution of 349 +/- 36 microns was achieved, with further improvement expected. The detailed tracking allows strong rejection of background gamma-rays, resulting in an effective gamma sensitivity of 10^-12 or less, coupled with stable, robust neutron identification. The detector also features a time resolution of 0.6 microseconds.

  12. A region segmentation based algorithm for building crystal position lookup table in scintillation detector

    CERN Document Server

    Wang, Hai Peng; Liu, Shuang Quan; Fan, Xin; Cao, Xue Xiang; Chai, Pei; Shan, Bao Ci

    2014-01-01

    In scintillation detector, scintillation crystals are typically made into 2-dimension modular array. The location of incident gamma-ray need be calibrated due to spatial response nonlinearity. Generally, position histograms, the characteristic flood response of scintillation detectors, are used for position calibration. In this paper, a position calibration method based on crystal position lookup table which maps the inaccurate location calculated by Anger logic to the exact hitting crystal position has been proposed, Firstly, position histogram is segmented into disconnected regions. Then crystal marking points are labeled by finding the centroids of regions. Finally, crystal boundaries are determined and crystal position lookup table is generated. The scheme is evaluated by the whole-body PET scanner and breast dedicated SPECT detector developed by Institute of High Energy Physics, Chinese Academy of Sciences. The results demonstrate that the algorithm is accurate, efficient, robust and general purpose.

  13. Discriminating cosmic muon and x-ray based on rising time using GEM detector

    CERN Document Server

    Hui-Yin, Wu; Xiao-Dong, Wang; Xian-Ming, Zhang; Hui-Rong, Qi; Wei, Zhang; Ke-Yan, Wu; Bi-Tao, Hu; Yi, Zhang

    2015-01-01

    Gas electron multiplier(GEM) detector is used in Cosmic Muon Scattering Tomography and neutron imaging in the last decade. In this work, a triple GEM device with an effective readout area of 10 cm X 10 cm is developed, and an experiment of discriminating between cosmic muon and x-ray based on rising time is tested. The energy resolution of GEM detector is tested by 55Fe ray source to prove the GEM detector has a good performance. The analysis of the complete signal-cycles allows to get the rising time and pulse heights. The experiment result indicates that cosmic muon and x-ray can be discriminated with an appropriate rising time threshold.

  14. Development of new system for environmental monitoring based on Al2O3:C detectors

    International Nuclear Information System (INIS)

    The thermoluminescence detectors (TLD) have been widely used for environmental radiation monitoring around nuclear facilities. In this study, a new environmental dosimeter based on Al2O3:C detectors placed in black Perspex holder with appropriate filtrations (0.2 mm Aluminium, 0.2 mm Copper and 0.4 mm Lead) has been proposed. The energy response beneath each filter was determined over a photon energy ranging from 20 keV to 1.3 MeV according to the recommendations of the International Standards Organisation (ISO). An algorithm has been elaborated in order to evaluate the ambient dose equivalent from linear combination of the TL-reading of each detector. The results obtained in terms of energy and angle responses are analysed regarding the environmental monitoring standard performance

  15. Characterization of microbulk detectors in argon- and neon-based mixtures

    CERN Document Server

    Iguaz, F J; Giganon, A; Giomataris, I

    2012-01-01

    A recent Micromegas manufacturing technique, so called Microbulk, has been developed, improving the uniformity and stability of this kind of detectors. Excellent energy resolutions have been obtained, reaching values as low as 11% FWHM at 5.9 keV in Ar+5%iC4H10. This detector has other advantages like its flexible structure, low material budget and high radio-purity. Two microbulk detectors with gaps of 50 and 25 um have been characterized in argon- and neon-based mixtures with ethane, isobutane and cyclohexane. The results will be presented and discussed. The gain curves have been fitted to the Rose-Korff gain model and dependences of the electron mean free path and the threshold energy for ionization have been obtained. The possible relation between these two parameters and the energy resolution will be also discussed.

  16. Impact of particles on the Planck HFI detectors: Ground-based measurements and physical interpretation

    CERN Document Server

    Catalano, A; Atik, Y; Benoit, A; Bréele, E; Bock, J J; Camus, P; Chabot, M; Charra, M; Crill, B P; Coron, N; Coulais, A; Désert, F -X; Fauvet, L; Giraud-Héraud, Y; Guillaudin, O; Holmes, W; Jones, W C; Lamarre, J -M; Macías-Pérez, J; Martinez, M; Miniussi, A; Monfardini, A; Pajot, F; Patanchon, G; Pelissier, A; Piat, M; Puget, J -L; Renault, C; Rosset, C; Santos, D; Sauvé, A; Spencer, L D; Sudiwala, R

    2014-01-01

    The Planck High Frequency Instrument (HFI) surveyed the sky continuously from August 2009 to January 2012. Its noise and sensitivity performance were excellent, but the rate of cosmic ray impacts on the HFI detectors was unexpectedly high. Furthermore, collisions of cosmic rays with the focal plane produced transient signals in the data (glitches) with a wide range of characteristics. A study of cosmic ray impacts on the HFI detector modules has been undertaken to categorize and characterize the glitches, to correct the HFI time-ordered data, and understand the residual effects on Planck maps and data products. This paper presents an evaluation of the physical origins of glitches observed by the HFI detectors. In order to better understand the glitches observed by HFI in flight, several ground-based experiments were conducted with flight-spare HFI bolometer modules. The experiments were conducted between 2010 and 2013 with HFI test bolometers in different configurations using varying particles and impact ener...

  17. The use of detectors based on ionisation recombination in radiation protection

    International Nuclear Information System (INIS)

    Intitial recombination of ionisation in a gas depends on the ionisation density and hence on the linear energy transfer along the tracks of charged particles. This effect can be used as a basis for instruments that respond to different types of ionising radiation approximately in the way required by the quality factor-linear energy transfer relation recommended by the ICRP for use in radiation protection. Empirical instruments based on ionisation recombination that have been used for radiation protection measurements are reviewed, and relations are derived from recombination theory that show that the response of such detectors can be readily predicted. The usefulness of recombination instruments in radiation protection is discussed and their advantages and limitations assessed. It is shown that their main application will be as reference instruments against which other detectors can be calibrated. As an extension to using recombination detectors as reference instruments, the feasibility of specifying radiation quality in terms of ionisation recombination is investigated. (author)

  18. Demonstrating a directional detector based on neon for characterizing high energy neutrons

    Science.gov (United States)

    Hexley, Allie

    2016-03-01

    MITPC is a gas-based time projection chamber used for detecting fast, MeV-scale neutrons. The standard version of the detector relies on a mixture of 600 torr gas composed of 87.5% helium-4 and 12.5% tetrafluoromethane for precisely measuring the energy and direction of neutron-induced nuclear recoils. I describe studies performed with a prototype detector investigating the use of neon, as a replacement for helium-4, in the gas mixture. My discussion focuses on the advantages of neon as the fast neutron target for high energy neutron events (100 MeV) and a demonstration that the mixture will be effective for this event class. I show that the achievable gain and transverse diffusion of drifting electrons in the neon mixture are acceptable and that the detector uptime lost due to voltage breakdowns in the amplification plane is negligible, compared to 20% with the helium-4 mixture.

  19. Superconducting detector of IR single-photons based on thin WSi films

    CERN Document Server

    Seleznev, V A; Vakhtomin, Yu B; Morozov, P V; Zolotov, P I; Vasilev, D D; Moiseev, K M; Malevannaya, E I; Smirnov, K V

    2016-01-01

    We have developed the deposition technology of WSi thin films 4 to 9 nm thick with high temperature values of superconducting transition (Tc~4 K). Based on deposed films there were produced nanostructures with indicative planar sizes ~100 nm, and the research revealed that even on nanoscale the films possess of high critical temperature values of the superconducting transition (Tc~3.3-3.7K ) which certifies high quality and homogeneity of the films created. The first experiments on creating superconducting single-photon detectors showed that the detectors SDE (system detection efficiency) with increasing bias current (Ib) reaches a constant value of ~30% (for 1550 nm) defined by infrared radiation absorption by the superconducting structure. To enhance radiation absorption by the superconductor there were created detectors with cavity structures which demonstrated a practically constant value of quantum efficiency >65% for bias currents Ib>=0.6Ic. The minimal dark counts level (DC) made 1 s^-1 limited with ba...

  20. Cardiac Multi-detector CT Segmentation Based on Multiscale Directional Edge Detector and 3D Level Set.

    Science.gov (United States)

    Antunes, Sofia; Esposito, Antonio; Palmisano, Anna; Colantoni, Caterina; Cerutti, Sergio; Rizzo, Giovanna

    2016-05-01

    Extraction of the cardiac surfaces of interest from multi-detector computed tomographic (MDCT) data is a pre-requisite step for cardiac analysis, as well as for image guidance procedures. Most of the existing methods need manual corrections, which is time-consuming. We present a fully automatic segmentation technique for the extraction of the right ventricle, left ventricular endocardium and epicardium from MDCT images. The method consists in a 3D level set surface evolution approach coupled to a new stopping function based on a multiscale directional second derivative Gaussian filter, which is able to stop propagation precisely on the real boundary of the structures of interest. We validated the segmentation method on 18 MDCT volumes from healthy and pathologic subjects using manual segmentation performed by a team of expert radiologists as gold standard. Segmentation errors were assessed for each structure resulting in a surface-to-surface mean error below 0.5 mm and a percentage of surface distance with errors less than 1 mm above 80%. Moreover, in comparison to other segmentation approaches, already proposed in previous work, our method presented an improved accuracy (with surface distance errors less than 1 mm increased of 8-20% for all structures). The obtained results suggest that our approach is accurate and effective for the segmentation of ventricular cavities and myocardium from MDCT images. PMID:26319010

  1. Optical ionization detector

    Science.gov (United States)

    Wuest, Craig R.; Lowry, Mark E.

    1994-01-01

    An optical ionization detector wherein a beam of light is split so that one arm passes through a fiber optics and the other arm passes through a gas-filled region, and uses interferometry to detect density changes in a gas when charged particles pass through it. The gas-filled region of the detector is subjected to a high electric field and as a charged particle traverses this gas region electrons are freed from the cathode and accelerated so as to generate an electron avalanche which is collected on the anode. The gas density is effected by the electron avalanche formation and if the index or refraction is proportional to the gas density the index will change accordingly. The detector uses this index change by modulating the one arm of the split light beam passing through the gas, with respect to the other arm that is passed through the fiber optic. Upon recombining of the beams, interference fringe changes as a function of the index change indicates the passage of charged particles through the gaseous medium.

  2. GaN/InGaN avalanche phototransistors

    Science.gov (United States)

    Shen, Shyh-Chiang; Kao, Tsung-Ting; Kim, Hee-Jin; Lee, Yi-Che; Kim, Jeomoh; Ji, Mi-Hee; Ryou, Jae-Hyun; Detchprohm, Theeradetch; Dupuis, Russell D.

    2015-03-01

    We report on III-nitride (III-N) avalanche phototransistor (APT) action by illuminating ultraviolet (UV) photons onto a GaN/InGaN npn heterojunction bipolar transistor in an open-base configuration. A high responsivity of >1 A/W was measured for the device operating at a collector-to-emitter voltage (VCE) of 68 A/W at VCE = 95 V. The InGaN APT demonstrates the feasibility of using III-N bipolar transistor structures for high-sensitivity UV photodetection applications.

  3. AvaDrone: An Autonomous Drone for Avalanche Victim Recovery

    OpenAIRE

    Dickensheets, Benjamin D.

    2015-01-01

    For the 179 Americans that are caught in avalanches each year, timely recovery often means the difference between life and death. The goal of this project was to design and build a prototype drone for a system to quickly and automatically locate a buried victim, using an on-board antenna to receive a signal from industry standard transmitting beacons. The design was based on a quad-rotor platform and uses Arduino hardware to receive a beacon signal and navigate the craft. In broad strokes...

  4. Advances in solid state photon detectors

    Science.gov (United States)

    Renker, D.; Lorenz, E.

    2009-04-01

    Semiconductor photodiodes were developed in the early `Forties approximately at the time when the photomultiplier tube became a commercial product (RCA 1939). Only in recent years, with the invention of the Geiger-mode avalanche photodiodes, have the semiconductor photo detectors reached sensitivity comparable to that of photomultiplier tubes. The evolution started in the `Sixties with the p-i-n (PIN) photodiode, a very successful device, which is still used in many detectors for high energy physics and a large number of other applications like radiation detection and medical imaging. The next step was the development of the avalanche photodiode (APD) leading to a substantial reduction of noise but not yet achieving single photon response. The weakest light flashes that can be detected by the PIN diode need to contain several hundreds of photons. An improvement of the sensitivity by 2 orders of magnitude was achieved by the development of the avalanche photodiode, a device with internal gain. At the end of the millennium, the semiconductor detectors evolved with the Geiger-mode avalanche photodiode into highly sensitive devices, which have an internal gain comparable to the gain of photomultiplier tubes and a response to single photons. A review of the semiconductor photo detector design and development, the properties and problems, some applications and a speculative outlook on the future evolution will be presented.

  5. An instrumentation amplifier based readout circuit for a dual element microbolometer infrared detector

    Science.gov (United States)

    de Waal, D. J.; Schoeman, J.

    2014-06-01

    The infrared band is widely used in many applications to solve problems stretching over very diverse fields, ranging from medical applications like inflammation detection to military, security and safety applications employing thermal imaging in low light conditions. At the heart of these optoelectrical systems lies a sensor used to detect incident infrared radiation, and in the case of this work our focus is on uncooled microbolometers as thermal detectors. Microbolometer based thermal detectors are limited in sensitivity by various parameters, including the detector layout and design, operating temperature, air pressure and biasing that causes self heating. Traditional microbolometers use the entire membrane surface for a single detector material. This work presents the design of a readout circuit amplifier where a dual detector element microbolometer is used, rather than the traditional single element. The concept to be investigated is based on the principle that both elements will be stimulated with a similar incoming IR signal and experience the same resistive change, thus creating a common mode signal. However, such a common mode signal will be rejected by a differential amplifier, thus one element is placed within a negative resistance converter to create a differential mode signal that is twice the magnitude of the comparable single mode signal of traditional detector designs. An instrumentation amplifier is used for the final stage of the readout amplifier circuit, as it allows for very high common mode rejection with proper trimming of the Wheatstone bridge to compensate for manufacturing tolerance. It was found that by implementing the above, improved sensitivity can be achieved.

  6. Signal processing for a single detector MOEMS based NIR micro spectrometer

    Science.gov (United States)

    Heberer, Andreas; Grüger, Heinrich; Zimmer, Fabian; Schenk, Harald; Kenda, Andreas; Frank, Albert; Scherf, Werner

    2005-10-01

    The examination of spectra in the NIR range is necessary for applications like process control, element analysis or medical systems. Typically integrated NIR spectrometers are based on optical setups with diffraction grating and detector arrays. The main disadvantage is price and availability of NIR array InGaAs-based detectors. The implementation of a scanning grating chip realized in a MOEMS technology which integrates the diffractive element makes it possible to detect spectra with single detectors time resolved. Either simple InGaAs photodiodes or cooled detectors may be used. The set up is a shrinked Czerny-Turner spectrometer. The light is coupled in by an optical fibre. After focussing the light passes the scanning grating moving at 150-500 Hz in a sinusoidal way. There it is split off in the different wavelength, the monochrome intensity is caught by a second mirror and led to the detector. The detector signal is amplified by a transimpedance stage and converted to digital with 12 bit resolution. The main part of the signal processing is done by a digital signal processor, which is used to unfold the sinusoidal position and calculate the final spectra. The data rate can be up to 3 MHz, then a spectrum is acquired every 2ms by using a 500Hz Mirror. Using the DSP, the spectrometer can operate autarkic without any PC. Then the spectrum is display on a 160 x 80 pixel graphic LCD. A keypad is used to control the functions. For communication a USB port is included, additional interfaces can be realized by a 16-pin expansion port, which is freely programmable, by the system firmware.

  7. Ticor-based scintillation detectors for detection of mixed radiation

    CERN Document Server

    Litvinov, L A; Kolner, V B; Ryzhikov, V D; Volkov, V G; Tarasov, V A; Zelenskaya, O V

    2002-01-01

    Detection of mixed radiation of thermal neutrons and gamma-rays have been realized using a new ceramic material based on small-crystalline long-wave scintillator alpha-Al sub 2 O sub 3 :Ti (Ticor) and lithium fluoride. Characteristics are presented for scintillators with Si-PIN-PD type photoreceivers and PMT under sup 2 sup 3 sup 9 Pu alpha-particles, sup 2 sup 0 sup 7 Bi internal conversion electrons,as well as sup 2 sup 4 sup 1 Am and sup 1 sup 3 sup 7 Cs gamma-quanta. Detection efficiency of thermal neutron is estimated for composite materials based on Ticor and lithium fluoride.

  8. Spectrum Sensor Hardware Implementation Based on Cyclostationary Feature Detector

    OpenAIRE

    Jussi Ryynänen; Aarno Pärssinen; Sami Kallioinen; Marko Kosunen; Vesa Turunen

    2011-01-01

    Cognitive radios utilize spectrum sensors to provide information about the surrounding radio environment. This enables cognitive radios to communicate at the same frequency bands with existing (primary) radio systems, and thereby improve the utilization of spectral resources. Furthermore, the spectrum sensor must be able to guarantee that the cognitive radio devices do not interfere with the primary system transmissions. This paper describes a hardware implementation of a spectrum sensor base...

  9. Human emotion detector based on genetic algorithm using lip features

    Science.gov (United States)

    Brown, Terrence; Fetanat, Gholamreza; Homaifar, Abdollah; Tsou, Brian; Mendoza-Schrock, Olga

    2010-04-01

    We predicted human emotion using a Genetic Algorithm (GA) based lip feature extractor from facial images to classify all seven universal emotions of fear, happiness, dislike, surprise, anger, sadness and neutrality. First, we isolated the mouth from the input images using special methods, such as Region of Interest (ROI) acquisition, grayscaling, histogram equalization, filtering, and edge detection. Next, the GA determined the optimal or near optimal ellipse parameters that circumvent and separate the mouth into upper and lower lips. The two ellipses then went through fitness calculation and were followed by training using a database of Japanese women's faces expressing all seven emotions. Finally, our proposed algorithm was tested using a published database consisting of emotions from several persons. The final results were then presented in confusion matrices. Our results showed an accuracy that varies from 20% to 60% for each of the seven emotions. The errors were mainly due to inaccuracies in the classification, and also due to the different expressions in the given emotion database. Detailed analysis of these errors pointed to the limitation of detecting emotion based on the lip features alone. Similar work [1] has been done in the literature for emotion detection in only one person, we have successfully extended our GA based solution to include several subjects.

  10. Fault detection and isolation for self powered neutron detectors based on Principal Component Analysis

    International Nuclear Information System (INIS)

    Highlights: • The methodology of Principal Component Analysis (PCA) is utilized to detect faults occurred in self powered neutron detectors. • The square prediction error based on the PCA model is employed to detect the SPND fault. • The Detector Validity Index (DVI) based on the reconstruction is employed to isolate the faulty SPND. • The fault detection and isolation scheme is validated with four types of simulated SPND faults. - Abstract: The self powered neutron detectors (SPNDs) play an important role in nuclear reactor monitoring. The 3-D power distribution and parameters used to evaluate the operation condition of reactor and the margin of safety can be determined using the measurement of SPNDs through power mapping procedure. Faulty SPNDs that are either completely or partially failed (hard fault or soft fault) provide incorrect information for monitoring. Correct detection and isolation of the faulty SPNDs are of primary importance to the efficient operation and management of the nuclear reactor. In this study, the methodology of Principal Component Analysis (PCA) is utilized to construct the mathematical models among various detectors at different axial location within the same string. The data used to build the mathematical models are generated by advanced neutronics code SMART rather than measurements. The square prediction error based on the model and the Detector Validity Index (DVI) based on the reconstruction are employed, respectively, to detect the SPND fault and to isolate the faulty SPNDs. The fault detection and isolation scheme is validated with four types of simulated SPND faults, i.e. bias, drifting, precision degradation and complete failure. The simulation results show that the proposed PCA based method can be used in the nuclear reactor to ensure that faulty SPNDs can be detected quickly

  11. A First Comparison of the responses of a He4-based fast-neutron detector and a NE-213 liquid-scintillator reference detector

    CERN Document Server

    Jebali, R; Annand, J R M; Chandra, R; Davatz, G; Fissum, K G; Friederich, H; Gendotti, U; Hall-Wilton, R; Håkansson, E; Kanaki, K; Lundin, M; Murer, D; Nilsson, B; Rosborg, A; Svensson, H

    2015-01-01

    A first comparison has been made between the pulse-shape discrimination characteristics of a novel He4-based pressurized scintillation detector and a NE-213 liquid-scintillator reference detector using an Am/Be mixed-field neutron and gamma-ray source and a high-resolution scintillation-pulse digitizer. In particular, the capabilities of the two fast neutron detectors to discriminate between neutrons and gamma-rays were investigated. The NE-213 liquid-scintillator reference cell produced a wide range of scintillation-light yields in response to the gamma-ray field of the source. In stark contrast, the He4-based detector registered a maximum scintillation-light yield of 750 keVee to the same gamma-ray field. Pulse-shape discrimination for particles with scintillation-light yields of more than 750 keVee was excellent in the case of the He4-based detector, and above 750 keVee its signal was unambiguously neutron.

  12. An Adaptive Failure Detector Based on Quality of Service in Peer-to-Peer Networks

    Directory of Open Access Journals (Sweden)

    Jian Dong

    2014-09-01

    Full Text Available The failure detector is one of the fundamental components that maintain high availability of Peer-to-Peer (P2P networks. Under different network conditions, the adaptive failure detector based on quality of service (QoS can achieve the detection time and accuracy required by upper applications with lower detection overhead. In P2P systems, complexity of network and high churn lead to high message loss rate. To reduce the impact on detection accuracy, baseline detection strategy based on retransmission mechanism has been employed widely in many P2P applications; however, Chen’s classic adaptive model cannot describe this kind of detection strategy. In order to provide an efficient service of failure detection in P2P systems, this paper establishes a novel QoS evaluation model for the baseline detection strategy. The relationship between the detection period and the QoS is discussed and on this basis, an adaptive failure detector (B-AFD is proposed, which can meet the quantitative QoS metrics under changing network environment. Meanwhile, it is observed from the experimental analysis that B-AFD achieves better detection accuracy and time with lower detection overhead compared to the traditional baseline strategy and the adaptive detectors based on Chen’s model. Moreover, B-AFD has better adaptability to P2P network.

  13. Pixelated Geiger-Mode Avalanche Photo-Diode Characterization through Dark Current Measurement

    CERN Document Server

    Amaudruz, Pierre-André; Gilhully, Colleen; Goertzen, Andrew; James, Lloyd; Kozlowski, Piotr; Retière, Fabrice; Shams, Ehsan; Sossi, Vesna; Stortz, Greg; Thiessen, Jonathan D; Thompson, Christopher J

    2013-01-01

    PIXELATED geiger-mode avalanche photodiodes(PPDs), often called silicon photomultipliers (SiPMs) are emerging as an excellent replacement for traditional photomultiplier tubes (PMTs) in a variety of detectors, especially those for subatomic physics experiments, which requires extensive test and operation procedures in order to achieve uniform responses from all the devices. In this paper, we show for two PPD brands, Hamamatsu MPPC and SensL SPM, that the dark noise rate, breakdown voltage and rate of correlated avalanches can be inferred from the sole measure of dark current as a function of operating voltage, hence greatly simplifying the characterization procedure. We introduce a custom electronics system that allows measurement for many devices concurrently, hence allowing rapid testing and monitoring of many devices at low cost. Finally, we show that the dark current of Hamamastu Multi-Pixel Photon Counter (MPPC) is rather independent of temperature at constant operating voltage, hence the current measure...

  14. Performance and simulation of a double-gap resistive plate chamber in the avalanche mode

    CERN Document Server

    Ahn Sung Hwan; Hong Byung Sik; Hong Seong Jong; Ito, M; Kang, T I; Kim, B I; Kim, J H; Kim, Y J; Kim, Y U; Koo, D G; Lee Hyup Woo; Lee, K B; Lee Kyong Sei; Lee Seok Jae; Lim, J K; Moon, D H; Nam, S K; Park, S; Park, W J; Rhee June Tak; Ryu, M S; Sim Kwang Souk

    2004-01-01

    We present a detailed analysis of the time and the charge signals of a prototype double-gap resistive plate chamber for the endcap region of the Compact Muon Solenoid (CMS) detector at the Large Hadron Collider (LHC). The chamber was built with relatively low-resistivity bakelite. The time and the charge results demonstrate that the high- voltage plateau, which satisfies various CMS requirements for the efficiency, the noise cluster rate, the fraction of the large signal, and the streamer probability, can be extended at least up to 400 V with the present design. In addition, a simple avalanche multiplication model is studied in detail. The model can reproduce the experimental charge spectra reasonably well. The charge information enables us to estimate the effective Townsend coefficient in avalanche-mode operation.

  15. EIT Based Gas Detector Design by Using Michelson Interferometer

    International Nuclear Information System (INIS)

    Electromagnetically induced transparency (EIT) is one of the interesting phenomena of light-matter interaction which modifies matter properties for propagation of light. In other words, we can change the absorption and refractive index (RI) in neighborhood of the resonant frequency using EIT. In this paper, we have doped 3-level quantum dots in one of the Michelson Interferometer's mirror and used EIT to change its RI. So, a controllable phase difference between lights in two arms of interferometer is created. Long response time is the main drawback of Michelson interferometer based sensor, which is resolved by this technique.

  16. Diagnosis of pneumothorax using a microwave-based detector

    Science.gov (United States)

    Ling, Geoffrey S. F.; Riechers, Ronald G., Sr.; Pasala, Krishna M.; Blanchard, Jeremy; Nozaki, Masako; Ramage, Anthony; Jackson, William; Rosner, Michael; Garcia-Pinto, Patricia; Yun, Catherine; Butler, Nathan; Riechers, Ronald G., Jr.; Williams, Daniel; Zeidman, Seth M.; Rhee, Peter; Ecklund, James M.; Fitzpatrick, Thomas; Lockhart, Stephen

    2001-08-01

    A novel method for identifying pneumothorax is presented. This method is based on a novel device that uses electromagnetic waves in the microwave radio frequency (RF) region and a modified algorithm previously used for the estimation of the angle of arrival of radar signals. In this study, we employ this radio frequency triage tool (RAFT) to the clinical condition of pneumothorax, which is a collapsed lung. In anesthetized pigs, RAFT can detect changes in the RF signature from a lung that is 20 percent or greater collapsed. These results are compared to chest x-ray. Both studies are equivalent in their ability to detect pneumothorax in pigs.

  17. Non smooth mechanics and rock avalanches : Description of the collisions and numerical simulation of granular flow

    OpenAIRE

    DIMNET, E; DAL PONT, S

    2005-01-01

    Rock avalanches are often modelled as the propagation of a collection of discrete bodies. In this paper we use a mechanical description of instantaneous collisions, based on the theory proposed by M Frémond (Frémond, 1995) to compute the flow. The theory is based on the principle of virtual work and numerical examples are presented.

  18. Metal frame as local protection of superconducting films from thermomagnetic avalanches

    Science.gov (United States)

    Mikheenko, P.; Vestgârden, J. I.; Chaudhuri, S.; Maasilta, I. J.; Galperin, Y. M.; Johansen, T. H.

    2016-03-01

    Thermomagnetic avalanches in superconducting films propagating extremely fast while forming unpredictable patterns, represent a serious threat for the performance of devices based on such materials. It is shown here that a normal-metal frame surrounding a selected region inside the film area can provide efficient protection from the avalanches during their propagation stage. Protective behavior is confirmed by magneto-optical imaging experiments on NbN films equipped with Cu and Al frames, and also by performing numerical simulations. Experimentally, it is found that while conventional flux creep is not affected by the frames, the dendritic avalanches are partially or fully screened by them. The level of screening depends on the ratio of the sheet conductance of the metal and the superconductor in the resistive state, and for ratios much larger than unity the screening is very efficient.

  19. Metal frame as local protection of superconducting films from thermomagnetic avalanches

    Directory of Open Access Journals (Sweden)

    P. Mikheenko

    2016-03-01

    Full Text Available Thermomagnetic avalanches in superconducting films propagating extremely fast while forming unpredictable patterns, represent a serious threat for the performance of devices based on such materials. It is shown here that a normal-metal frame surrounding a selected region inside the film area can provide efficient protection from the avalanches during their propagation stage. Protective behavior is confirmed by magneto-optical imaging experiments on NbN films equipped with Cu and Al frames, and also by performing numerical simulations. Experimentally, it is found that while conventional flux creep is not affected by the frames, the dendritic avalanches are partially or fully screened by them. The level of screening depends on the ratio of the sheet conductance of the metal and the superconductor in the resistive state, and for ratios much larger than unity the screening is very efficient.

  20. The scientific potential of space-based gravitational wave detectors

    CERN Document Server

    Gair, Jonathan R

    2014-01-01

    The millihertz gravitational wave band can only be accessed with a space-based interferometer, but it is one of the richest in potential sources. Observations in this band have amazing scientific potential. The mergers between massive black holes with mass in the range 10 thousand to 10 million solar masses, which are expected to occur following the mergers of their host galaxies, produce strong millihertz gravitational radiation. Observations of these systems will trace the hierarchical assembly of structure in the Universe in a mass range that is very difficult to probe electromagnetically. Stellar mass compact objects falling into such black holes in the centres of galaxies generate detectable gravitational radiation for several years prior to the final plunge and merger with the central black hole. Measurements of these systems offer an unprecedented opportunity to probe the predictions of general relativity in the strong-field and dynamical regime. Millihertz gravitational waves are also generated by mil...

  1. Advanced Fluorescence Protein-Based Synapse-Detectors.

    Science.gov (United States)

    Lee, Hojin; Oh, Won Chan; Seong, Jihye; Kim, Jinhyun

    2016-01-01

    The complex information-processing capabilities of the central nervous system emerge from intricate patterns of synaptic input-output relationships among various neuronal circuit components. Understanding these capabilities thus requires a precise description of the individual synapses that comprise neural networks. Recent advances in fluorescent protein engineering, along with developments in light-favoring tissue clearing and optical imaging techniques, have rendered light microscopy (LM) a potent candidate for large-scale analyses of synapses, their properties, and their connectivity. Optically imaging newly engineered fluorescent proteins (FPs) tagged to synaptic proteins or microstructures enables the efficient, fine-resolution illumination of synaptic anatomy and function in large neural circuits. Here we review the latest progress in fluorescent protein-based molecular tools for imaging individual synapses and synaptic connectivity. We also identify associated technologies in gene delivery, tissue processing, and computational image analysis that will play a crucial role in bridging the gap between synapse- and system-level neuroscience. PMID:27445785

  2. Bioaerosol collection and concentration for microseparations-based detectors.

    Energy Technology Data Exchange (ETDEWEB)

    Cummings, Eric B. (Sandia National Laboratories, Livermore, CA); Ellis, C. R. Bowe (Sandia National Laboratories, Livermore, CA); Kanouff, Michael P. (Sandia National Laboratories, Livermore, CA); Rader, Daniel John; Wally, Karl (Sandia National Laboratories, Livermore, CA)

    2005-03-01

    The ability to detect Weapons of Mass Destruction biological agents rapidly and sensitively is vital to homeland security, spurring development of compact detection systems at Sandia and elsewhere. One such system is Sandia's microseparations-based pChemLab. Many bio-agents are serious health threats even at extremely low concentrations. Therefore, a universal challenge for detection systems is the efficient collection and selective transport of highly diffuse bio-agents against the enormous background of benign particles and species ever present in the ambient environment. We have investigated development of a ''front end'' system for the collection, preconcentration, and selective transport of aerosolized biological agents from dilute (1-10 active particles per liter of air) atmospheric samples, to ultimate concentrations of {approx}20 active particles per microliter of liquid, for interface with microfluidic-based analyses and detection systems. Our approach employs a Sandia-developed aerosol particle-focusing microseparator array to focus size-selected particles into a mating microimpinger array of open microfluidic transport channels. Upon collection (i.e., impingement, submergence, and liquid suspension), microfluidic dielectrophoretic particle concentrators and sorters can be employed to further concentrate and selectively transport bio-agent particles to the sample preparation stages of microfluidic analyses and detection systems. This report documents results in experimental testing, modeling and analysis, component design, and materials fabrication critical to establishing proof-of-principle for this collection ''front end''. Outstanding results have been achieved for the aerodynamic microseparator, and for the post-collection dielectrophoretic concentrator and sorter. Results have been obtained for the microimpinger, too, but issues of particle-trapping by surface tension in liquid surfaces have proven

  3. The MAPS-based vertex detector for the STAR experiment: Lessons learned and performance

    Science.gov (United States)

    Contin, Giacomo

    2016-09-01

    The PiXeL detector (PXL) of the STAR experiment at RHIC is the first application of the state-of-the-art thin Monolithic Active Pixel Sensors (MAPS) technology in a collider environment. The PXL, together with the Intermediate Silicon Tracker (IST) and the Silicon Strip Detector (SSD), form the Heavy Flavor Tracker (HFT), which has been designed to improve the vertex resolution and extend the STAR measurement capabilities in the heavy flavor domain, providing a clean probe for studying the Quark-Gluon Plasma. The two PXL layers are placed at a radius of 2.8 and 8 cm from the beam line, respectively, and is based on ultra-thin high resolution MAPS sensors. The sensor features 20.7 μm pixel pitch, 185.6 μs readout time and 170 mW/cm2 power dissipation. The detector is air-cooled, allowing a global material budget of 0.4% radiation length on the innermost layer. A novel mechanical approach to detector insertion allows for fast installation and integration of the pixel sub detector. The HFT took data in Au+Au collisions at 200 GeV during the 2014 RHIC run. Modified during the RHIC shutdown to improve its reliability, material budget, and tracking capabilities, the HFT took data in p+p and p+Au collisions at √sNN=200 GeV in the 2015 RHIC run. In this paper we present detector specifications, experience from the construction and operations, and lessons learned. We also show preliminary results from 2014 Au+Au data analyses, demonstrating the capabilities of charm reconstruction with the HFT.

  4. Development of Fuses for Protection of Geiger-Mode Avalanche Photodiode Arrays

    Science.gov (United States)

    Grzesik, Michael; Bailey, Robert; Mahan, Joe; Ampe, Jim

    2015-11-01

    Current-limiting fuses composed of Ti/Al/Ni were developed for use in Geiger-mode avalanche photodiode arrays for each individual pixel in the array. The fuses were designed to burn out at ˜4.5 × 10-3 A and maintain post-burnout leakage currents less than 10-7 A at 70 V sustained for several minutes. Experimental fuse data are presented and successful incorporation of the fuses into a 256 × 64 pixel InP-based Geiger-mode avalanche photodiode array is reported.

  5. GATE simulation of a LYSO-based SPECT imager: Validation and detector optimization

    Science.gov (United States)

    Li, Suying; Zhang, Qiushi; Xie, Zhaoheng; Liu, Qi; Xu, Baixuan; Yang, Kun; Li, Changhui; Ren, Qiushi

    2015-02-01

    This paper presents a small animal SPECT system that is based on cerium doped lutetium-yttrium oxyorthosilicate (LYSO) scintillation crystal, position sensitive photomultiplier tubes (PSPMTs) and parallel hole collimator. Spatial resolution test and animal experiment were performed to demonstrate the imaging performance of the detector. Preliminary results indicated a spatial resolution of 2.5 mm at FWHM that cannot meet our design requirement. Therefore, we simulated this gamma camera using GATE (GEANT 4 Application for Tomographic Emission) aiming to make detector spatial resolution less than 2 mm. First, the GATE simulation process was validated through comparison between simulated and experimental data. This also indicates the accuracy and effectiveness of GATE simulation for LYSO-based gamma camera. Then the different detector sampling methods (crystal size with 1.5, and 1 mm) and collimator design (collimator height with 30, 34.8, 38, and 43 mm) were studied to figure out an optimized parameter set. Detector sensitivity changes were also focused on with different parameters set that generated different spatial resolution results. Tradeoff curves of spatial resolution and sensitivity were plotted to determine the optimal collimator height with different sampling methods. Simulation results show that scintillation crystal size of 1 mm and collimator height of 38 mm, which can generate a spatial resolution of ~1.8 mm and sensitivity of ~0.065 cps/kBq, can be an ideal configuration for our SPECT imager design.

  6. A Wireless Sensor Network-Based Portable Vehicle Detector Evaluation System

    Directory of Open Access Journals (Sweden)

    Seong-eun Yoo

    2013-01-01

    Full Text Available In an upcoming smart transportation environment, performance evaluations of existing Vehicle Detection Systems are crucial to maintain their accuracy. The existing evaluation method for Vehicle Detection Systems is based on a wired Vehicle Detection System reference and a video recorder, which must be operated and analyzed by capable traffic experts. However, this conventional evaluation system has many disadvantages. It is inconvenient to deploy, the evaluation takes a long time, and it lacks scalability and objectivity. To improve the evaluation procedure, this paper proposes a Portable Vehicle Detector Evaluation System based on wireless sensor networks. We describe both the architecture and design of a Vehicle Detector Evaluation System and the implementation results, focusing on the wireless sensor networks and methods for traffic information measurement. With the help of wireless sensor networks and automated analysis, our Vehicle Detector Evaluation System can evaluate a Vehicle Detection System conveniently and objectively. The extensive evaluations of our Vehicle Detector Evaluation System show that it can measure the traffic information such as volume counts and speed with over 98% accuracy.

  7. A Wireless Sensor Network-Based Portable Vehicle Detector Evaluation System

    Science.gov (United States)

    Yoo, Seong-eun

    2013-01-01

    In an upcoming smart transportation environment, performance evaluations of existing Vehicle Detection Systems are crucial to maintain their accuracy. The existing evaluation method for Vehicle Detection Systems is based on a wired Vehicle Detection System reference and a video recorder, which must be operated and analyzed by capable traffic experts. However, this conventional evaluation system has many disadvantages. It is inconvenient to deploy, the evaluation takes a long time, and it lacks scalability and objectivity. To improve the evaluation procedure, this paper proposes a Portable Vehicle Detector Evaluation System based on wireless sensor networks. We describe both the architecture and design of a Vehicle Detector Evaluation System and the implementation results, focusing on the wireless sensor networks and methods for traffic information measurement. With the help of wireless sensor networks and automated analysis, our Vehicle Detector Evaluation System can evaluate a Vehicle Detection System conveniently and objectively. The extensive evaluations of our Vehicle Detector Evaluation System show that it can measure the traffic information such as volume counts and speed with over 98% accuracy. PMID:23344388

  8. GATE simulation of a LYSO-based SPECT imager: Validation and detector optimization

    Energy Technology Data Exchange (ETDEWEB)

    Li, Suying [Department of Biomedicine and Engineering, College of Engineering, Peking University, No. 5 Yiheyuan Road, Beijing 100871 (China); Zhang, Qiushi [Institute for Drug and Instrument Control of Health Department GLD of PLA, No. 17 Fengtai West Road, Beijing 100071 (China); Xie, Zhaoheng; Liu, Qi [Department of Biomedicine and Engineering, College of Engineering, Peking University, No. 5 Yiheyuan Road, Beijing 100871 (China); Xu, Baixuan [The General Hospital of Chinese People’s Liberation Army, No. 28 Fuxing Road, Beijing 100039 (China); Yang, Kun; Li, Changhui [Department of Biomedicine and Engineering, College of Engineering, Peking University, No. 5 Yiheyuan Road, Beijing 100871 (China); Ren, Qiushi, E-mail: renqsh@coe.pku.edu.cn [Department of Biomedicine and Engineering, College of Engineering, Peking University, No. 5 Yiheyuan Road, Beijing 100871 (China)

    2015-02-11

    This paper presents a small animal SPECT system that is based on cerium doped lutetium–yttrium oxyorthosilicate (LYSO) scintillation crystal, position sensitive photomultiplier tubes (PSPMTs) and parallel hole collimator. Spatial resolution test and animal experiment were performed to demonstrate the imaging performance of the detector. Preliminary results indicated a spatial resolution of 2.5 mm at FWHM that cannot meet our design requirement. Therefore, we simulated this gamma camera using GATE (GEANT 4 Application for Tomographic Emission) aiming to make detector spatial resolution less than 2 mm. First, the GATE simulation process was validated through comparison between simulated and experimental data. This also indicates the accuracy and effectiveness of GATE simulation for LYSO-based gamma camera. Then the different detector sampling methods (crystal size with 1.5, and 1 mm) and collimator design (collimator height with 30, 34.8, 38, and 43 mm) were studied to figure out an optimized parameter set. Detector sensitivity changes were also focused on with different parameters set that generated different spatial resolution results. Tradeoff curves of spatial resolution and sensitivity were plotted to determine the optimal collimator height with different sampling methods. Simulation results show that scintillation crystal size of 1 mm and collimator height of 38 mm, which can generate a spatial resolution of ∼1.8 mm and sensitivity of ∼0.065 cps/kBq, can be an ideal configuration for our SPECT imager design.

  9. GATE simulation of a LYSO-based SPECT imager: Validation and detector optimization

    International Nuclear Information System (INIS)

    This paper presents a small animal SPECT system that is based on cerium doped lutetium–yttrium oxyorthosilicate (LYSO) scintillation crystal, position sensitive photomultiplier tubes (PSPMTs) and parallel hole collimator. Spatial resolution test and animal experiment were performed to demonstrate the imaging performance of the detector. Preliminary results indicated a spatial resolution of 2.5 mm at FWHM that cannot meet our design requirement. Therefore, we simulated this gamma camera using GATE (GEANT 4 Application for Tomographic Emission) aiming to make detector spatial resolution less than 2 mm. First, the GATE simulation process was validated through comparison between simulated and experimental data. This also indicates the accuracy and effectiveness of GATE simulation for LYSO-based gamma camera. Then the different detector sampling methods (crystal size with 1.5, and 1 mm) and collimator design (collimator height with 30, 34.8, 38, and 43 mm) were studied to figure out an optimized parameter set. Detector sensitivity changes were also focused on with different parameters set that generated different spatial resolution results. Tradeoff curves of spatial resolution and sensitivity were plotted to determine the optimal collimator height with different sampling methods. Simulation results show that scintillation crystal size of 1 mm and collimator height of 38 mm, which can generate a spatial resolution of ∼1.8 mm and sensitivity of ∼0.065 cps/kBq, can be an ideal configuration for our SPECT imager design

  10. The sensitivity of the ICAL detector at India-based Neutrino Observatory to neutrino oscillation parameters

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Daljeet; Naimuddin, Md.; Kumar, Sanjeev [University of Delhi, Department of Physics and Astrophysics, Delhi (India)

    2015-04-01

    The India-based Neutrino Observatory will host a 50 kt magnetized iron calorimeter (ICAL) detector that will be able to detect muon tracks and hadron showers produced by charged-current muon neutrino interactions in the detector. The ICAL experiment will be able to determine the precision of atmospheric neutrino mixing parameters and neutrino mass hierarchy using atmospheric muon neutrinos through the earth matter effect. In this paper, we report on the sensitivity for the atmospheric neutrino mixing parameters(sin{sup 2}θ{sub 23} and vertical stroke Δm{sub 32}{sup 2} vertical stroke) and octant sensitivity for the ICAL detector using the reconstructed neutrino energy and muon direction as observables. We apply realistic resolutions and efficiencies obtained by the ICAL collaboration with a GEANT4-based simulation to reconstruct neutrino energy and muon direction. Our study shows that using neutrino energy and muon direction as observables for a χ{sup 2} analysis, the ICAL detector can measure sin{sup 2}θ{sub 23} and vertical stroke Δm{sub 32}{sup 2} vertical stroke with 13% and 4% uncertainties at 1σ confidence level and can rule out the wrong octant of θ{sub 23} with 2σ confidence level for 10 years of exposure. (orig.)

  11. Test of a prototype neutron spectrometer based on diamond detectors in a fast reactor

    CERN Document Server

    Osipenko, M; Ripani, M; Pillon, M; Ricco, G; Caiffi, B; Cardarelli, R; Verona-Rinati, G; Argiro, S

    2015-01-01

    A prototype of neutron spectrometer based on diamond detectors has been developed. This prototype consists of a $^6$Li neutron converter sandwiched between two CVD diamond crystals. The radiation hardness of the diamond crystals makes it suitable for applications in low power research reactors, while a low sensitivity to gamma rays and low leakage current of the detector permit to reach good energy resolution. A fast coincidence between two crystals is used to reject background. The detector was read out using two different electronic chains connected to it by a few meters of cable. The first chain was based on conventional charge-sensitive amplifiers, the other used a custom fast charge amplifier developed for this purpose. The prototype has been tested at various neutron sources and showed its practicability. In particular, the detector was calibrated in a TRIGA thermal reactor (LENA laboratory, University of Pavia) with neutron fluxes of $10^8$ n/cm$^2$s and at the 3 MeV D-D monochromatic neutron source na...

  12. GEM400: A front-end chip based on capacitor-switch array for pixel-based GEM detector

    International Nuclear Information System (INIS)

    The upgrade of Beijing Synchrotron Radiation Facility (BSRF) needs two-dimensional position-sensitive detection equipment to improve the experimental performance. Gas Electron Multiplier (GEM) detector, in particular, pixel-based GEM detector has good application prospects in the domain of synchrotron radiation. The read-out of larger scale pixel-based GEM detector is difficult for the high density of the pixels (PAD for collecting electrons). In order to reduce the number of cables, this paper presents a read-out scheme for pixel-based GEM detector, which is based on System-in-Package technology and ASIC technology. We proposed a circuit structure based on capacitor switch array circuit, and design a chip GEM400, which is a 400 channels ASIC. The proposed circuit can achieve good stability and low power dissipation. The chip is implemented in a 0.35μm CMOS process. The basic functional circuitry in ths chip includes analog switch, analog buffer, voltage amplifier, bandgap and control logic block, and the layout of this chip takes 5mm × 5mm area. The simulation results show that the chip can allow the maximum amount of input charge 70pC on the condition of 100pF external integrator capacitor. Besides, the chip has good channel uniformity (INL is better than 0.1%) and lower power dissipation.

  13. Joint Preprocesser-Based Detectors for One-Way and Two-Way Cooperative Communication Networks

    KAUST Repository

    Abuzaid, Abdulrahman I.

    2014-05-01

    Efficient receiver designs for cooperative communication networks are becoming increasingly important. In previous work, cooperative networks communicated with the use of L relays. As the receiver is constrained, channel shortening and reduced-rank techniques were employed to design the preprocessing matrix that reduces the length of the received vector from L to U. In the first part of the work, a receiver structure is proposed which combines our proposed threshold selection criteria with the joint iterative optimization (JIO) algorithm that is based on the mean square error (MSE). Our receiver assists in determining the optimal U. Furthermore, this receiver provides the freedom to choose U for each frame depending on the tolerable difference allowed for MSE. Our study and simulation results show that by choosing an appropriate threshold, it is possible to gain in terms of complexity savings while having no or minimal effect on the BER performance of the system. Furthermore, the effect of channel estimation on the performance of the cooperative system is investigated. In the second part of the work, a joint preprocessor-based detector for cooperative communication networks is proposed for one-way and two-way relaying. This joint preprocessor-based detector operates on the principles of minimizing the symbol error rate (SER) instead of minimizing MSE. For a realistic assessment, pilot symbols are used to estimate the channel. From our simulations, it can be observed that our proposed detector achieves the same SER performance as that of the maximum likelihood (ML) detector with all participating relays. Additionally, our detector outperforms selection combining (SC), channel shortening (CS) scheme and reduced-rank techniques when using the same U. Finally, our proposed scheme has the lowest computational complexity.

  14. An Atomically Layered InSe Avalanche Photodetector.

    Science.gov (United States)

    Lei, Sidong; Wen, Fangfang; Ge, Liehui; Najmaei, Sina; George, Antony; Gong, Yongji; Gao, Weilu; Jin, Zehua; Li, Bo; Lou, Jun; Kono, Junichiro; Vajtai, Robert; Ajayan, Pulickel; Halas, Naomi J

    2015-05-13

    Atomically thin photodetectors based on 2D materials have attracted great interest due to their potential as highly energy-efficient integrated devices. However, photoinduced carrier generation in these media is relatively poor due to low optical absorption, limiting device performance. Current methods for overcoming this problem, such as reducing contact resistances or back gating, tend to increase dark current and suffer slow response times. Here, we realize the avalanche effect in a 2D material-based photodetector and show that avalanche multiplication can greatly enhance the device response of an ultrathin InSe-based photodetector. This is achieved by exploiting the large Schottky barrier formed between InSe and Al electrodes, enabling the application of a large bias voltage. Plasmonic enhancement of the photosensitivity, achieved by patterning arrays of Al nanodisks onto the InSe layer, further improves device efficiency. With an external quantum efficiency approaching 866%, a dark current in the picoamp range, and a fast response time of 87 μs, this atomic layer device exhibits multiple significant advances in overall performance for this class of devices.

  15. Model-based detector and extraction of weak signal frequencies from chaotic data.

    Science.gov (United States)

    Zhou, Cangtao; Cai, Tianxing; Heng Lai, Choy; Wang, Xingang; Lai, Ying-Cheng

    2008-03-01

    Detecting a weak signal from chaotic time series is of general interest in science and engineering. In this work we introduce and investigate a signal detection algorithm for which chaos theory, nonlinear dynamical reconstruction techniques, neural networks, and time-frequency analysis are put together in a synergistic manner. By applying the scheme to numerical simulation and different experimental measurement data sets (Henon map, chaotic circuit, and NH(3) laser data sets), we demonstrate that weak signals hidden beneath the noise floor can be detected by using a model-based detector. Particularly, the signal frequencies can be extracted accurately in the time-frequency space. By comparing the model-based method with the standard denoising wavelet technique as well as supervised principal components analysis detector, we further show that the nonlinear dynamics and neural network-based approach performs better in extracting frequencies of weak signals hidden in chaotic time series.

  16. An F-statistic based multi-detector veto for detector artifacts in continuous-wave gravitational wave data

    OpenAIRE

    Keitel, D.; Prix, R.; Papa, M.; Siddiqi, M.

    2012-01-01

    Continuous gravitational waves (CW) are expected from spinning neutron stars with non-axisymmetric deformations. A network of interferometric detectors (LIGO, Virgo and GEO600) is looking for these signals. They are predicted to be very weak and retrievable only by integration over long observation times. One of the standard methods of CW data analysis is the multi-detector F-statistic. In a typical search, the F-statistic is computed over a range in frequency, spin-down and sky position, and...

  17. Status and progress of the novel photon detectors based on THGEM and hybrid MPGD architectures

    International Nuclear Information System (INIS)

    We are developing large size THick GEM (THGEM)-based detectors of single photons, mainly meant for Cherenkov imaging applications. The R and D programme includes the complete characterisation of the THGEM electron multipliers, the study of the aspects related to the detection of single photons and the engineering towards large size detector prototypes. Our most recent achievements include dedicated studies concerning the ion backflow to the photocathode; relevant progress in the engineering aspects, in particularly related to the production of large-size THGEMs, where the strict correlation between the local gain-value and the local thickness-value has been demonstrated and a 300×300 mm2 active area detector has been successfully operated at the CERN PS T10 test beam; the introduction of a new hybrid detector architecture, offering promising performance, which is formed by a THGEM layer which acts both as photocathode and pre-amplification device, followed by a MICROMEGAS (MM) multiplication stage. We report about the general status of the R and D programme and, in detail, about the recent progress. - Highlights: • The paper presents a study of micropattern gas electron multipliers based on THGEMs. • The paper focuses on the use of THGEMs as photon detector for RICH application: single photon detection. • The paper addresses the R and D activity and the results obtained both in laboratory activities and test beams. • The paper describes the technological challenges to instrument large surfaces, presenting possible solutions to the critical issues faced during the R and D activity

  18. Recent progress in InSb based quantum detectors in Israel

    Science.gov (United States)

    Klipstein, Philip; Aronov, Daniel; Ezra, Michael ben; Barkai, Itzik; Berkowicz, Eyal; Brumer, Maya; Fraenkel, Rami; Glozman, Alex; Grossman, Steve; Jacobsohn, Eli; Klin, Olga; Lukomsky, Inna; Shkedy, Lior; Shtrichman, Itay; Snapi, Noam; Yassen, Michael; Weiss, Eliezer

    2013-07-01

    InSb is a III-V binary semiconductor material with a bandgap wavelength of 5.4 μm at 77 K, well matched to the 3-5 μm MWIR atmospheric transmission window. When configured as a Focal Plane Array (FPA) detector, InSb photodiodes offer a large quantum efficiency, combined with excellent uniformity and high pixel operability. As such, InSb arrays exhibit good scalability and are an excellent choice for large format FPAs at a reasonable cost. The dark current is caused by Generation-Recombination (G-R) centres in the diode depletion region, and this leads to a typical operating temperature of ˜80 K in detectors with a planar implanted p-n junction. Over the last 15 years SCD has developed and manufactured a number of different 2-dimensional planar FPA formats, with pitches in the range of 15-30 μm. In recent years a new epi-InSb technology has been developed at SCD, in which the G-R contribution to the dark current is reduced. This enables InSb detector operation at 95-100 K, with equivalent performance to standard InSb at 80 K. In addition, using a new patented XBnn device architecture in which the G-R current is totally suppressed, epitaxial InAsSb detectors have been developed with a bandgap wavelength of 4.2 μm, which can operate in the 150-170 K range. In this short review of the past two decades, a number of key achievements in SCD's InSb based detector development program are described. These include High Operating Temperature (HOT) epi-InSb FPAs, large format megapixel FPAs with high functionality using a digital Read Out Integrated Circuit (ROIC), and ultra low Size, Weight and Power (SWaP) FPAs based on the HOT XBnn architecture.

  19. Performance of the Insertable B-Layer for the ATLAS Pixel Detector during Quality Assurance and a Novel Pixel Detector Readout Concept based on PCIe

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00356268; Pernegger, Heinz

    2016-07-27

    During the first long shutdown of the LHC the Pixel detector has been upgraded with a new 4th innermost layer, the Insertable B-Layer (IBL). The IBL will increase the tracking performance and help with higher than nominal luminosity the LHC will produce. The IBL is made up of 14 staves and in total 20 staves have been produced for the IBL. This thesis presents the results of the final quality tests performed on these staves in an detector-like environment, in order to select the 14 best of the 20 staves for integration onto the detector. The test setup as well as the testing procedure is introduced and typical results of each testing stage are shown and discussed. The overall performance of all staves is presented in regards to: tuning performance, radioactive source measurements, and number of failing pixels. Other measurement, which did not directly impact the selection of staves, but will be important for the operation of the detector or production of a future detector, are included. Based on the experienc...

  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. Development of Si-based detectors for intermediate energy heavy-ion physics at a storage-ring accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Whitlow, H.J.; Jaworowski, J.; Leandersson, M.; El Bouanani, M. [Lund Institute of Technology, Solvegatan Lund, (Sweden). Department of Nuclear Physics; Jakobsson, B. [Lund Univ. (Sweden). Dept. of Cosmic and Subatomic Physics; Romanski, J.; Westerberg, L.; Van Veldhuizen, E.J. [Uppsala Univ. (Sweden); The Chicsi Collaboration

    1996-12-31

    Ultrahigh vacuum (UHV) compatible Si detectors are being developed by the CELSIUS Heavy lon Collaboration (CHIC) for measuring the energy and identity of Intermediate Mass Fragments (IMF) with Z {approx} 3 - 12 and energies of 0.7 - I 0 A MeV. Here we give an overview of the development of Si {delta}E-E detector telescopes and investigations on IMF identification based on the pulse shape from Si-detectors where the particles impinge on the rear-face of the detector. 9 refs., 4 figs.

  2. New Developments in the Position Sensitive Detectors Based on Microchannel Plates

    Science.gov (United States)

    Tremsin, A. S.; Siegmund, O. H. W.

    2002-11-01

    We report on the latest developments in position sensitive photon counting detectors based on microchannel plates. Substantial improvement of the spatial resolution was achieved with introduction of new readout technology, namely crossed strip (XS) anode, and corresponding processing electronics. The spatial resolution of XS readout appeared to be as small as ~3-4 μm FWHM. Reduction of the total detector gain (down to 106 and potentially lower) without compromising the spatial accuracy allows detector operation at much higher local and global counting rates since the microchannel recharge time becomes smaller. Recent developments of novel microchannel plate technologies provide basis for substantial increase of the spectral sensitivity and quantum efficiency of MCP detectors. We have tested a number of new Silicon micromachined MCPs The new MCP technologies should allow deposition of completely new photocathode materials directly on the front surface of microchannel plates (opaque photocathodes). Opposite to standard glass MCPs new Silicon MCPs can sustain high temperatures (-800 C°) required for the photocathode deposition and activation processes.

  3. A spectroscopy-based detector to monitor tomato growth condition in greenhouse

    Science.gov (United States)

    Yang, Ce; Li, Minzan; Cui, Di

    2008-12-01

    A spectroscopy-based detector is developed to measure the nitrogen and chlorophyll content of tomato leaves and then to predict the growth condition of tomato plants in greenhouse. The detector uses two wavebands, 527 nm and 762 nm, since it is proved that these wavebands are sensitive to nitrogen and chlorophyll content in plant leaves by previous field test. The detector contains: A Y-type optic fiber, two silicon photocells, a signal processing unit, and a MCU. Light reflection from tomato leaves is transmitted by the Y-type optic fiber to the surface of the silicon photo cells, which transfer optical signal into electrical signal. Then the analog signal is amplified to conform to the TTL level signal standard and finally converted to digital signal by MAX186. After that, the MCU carries on a series of actions, including data calculating, displaying and storage. Using the measured data, the Normalized Difference Vegetation Index (NDVI) is calculated to estimate the nitrogen and chlorophyll content in plant leaves. The result is directly displayed on an LCD screen. Users have an option in saving data, either into a USB-memory stick or into a database over the PC serial port. The detector is portable, inexpensive, and convenient, which make it meet farmers' need in China. The performance test shows that the growth model works very well, and the device has high accuracy in predicting the growth condition of tomato plants in greenhouse.

  4. Gamma-spectrometric module based on HPGe detector for radiation portal monitors

    Directory of Open Access Journals (Sweden)

    Kondratjev Vladimir

    2015-01-01

    Full Text Available The appearance of small-sized and powerful enough electric cryocoolers of various types on the market, has opened the perspective of HPGe detectors application, cooled by such coolers, in radiation portal monitors. The first results of a spectrometric module based on HPGe detector with relative efficiency of 45% cooled by a Stirling-cycle cryocooler, are presented. The spectrometer has provided energy resolutions of less than 0.95 keV and 1.95 keV at energies of 122 keV and 1332 keV, respectively. The deterioration of the energy resolution of HPGe detector cooled by electric cryocooler in comparison to the resolution with liquid nitrogen cooling was about 8% at the energy of 1332 keV. With the use of activated filters to suppress pulses produced by the mechanical vibrations, the energy resolution of the spectrometer was 0.8 keV and 1.8 keV, respectively, however, the detector relative efficiency at the energy of 1332 keV has dropped to 39 %.

  5. Ion track reconstruction in 3D using alumina-based fluorescent nuclear track detectors

    CERN Document Server

    Niklas, Martin; Akselrod, Mark S; Abollahi, Amir; Jäkel, Oliver; Greilich, Steffen

    2013-01-01

    Fluorescent nuclear track detectors (FNTDs) based on Al2O3:C,Mg single crystal combined with confocal microscopy provide 3D information on ion tracks with a resolution only limited by light diffraction. FNTDs are also ideal substrates to be coated with cells to engineer cell-fluorescent ion track hybrid detectors. This radiobiological tool enables a novel platform linking cell responses to physical dose deposition on a sub-cellular level in proton and heavy ion therapies. To achieve spatial correlation between single ion hits in the cell coating and its biological response the ion traversals have to be reconstructed in 3D using the depth information gained by the FNTD read-out. FNTDs were coated with a confluent human lung adenocarcinoma epithelial cell layer. Carbon ion irradiation of the hybrid detector was performed perpendicular and angular to the detector surface. In-situ imaging of the fluorescently labeled cell layer and the FNTD was performed in a sequential read-out. Making use of the trajectory info...

  6. Ultracold neutron detectors based on {sup 10}B converters used in the qBounce experiments

    Energy Technology Data Exchange (ETDEWEB)

    Jenke, Tobias, E-mail: tjenke@ati.ac.at [Atominstitut TU Wien, Stadionallee 2, 1020 Wien (Austria); Cronenberg, Gunther; Filter, Hanno [Atominstitut TU Wien, Stadionallee 2, 1020 Wien (Austria); Geltenbort, Peter [Institut Laue-Langevin, 6 rue Jules Horowitz, 38042 Grenoble Cedex 9 (France); Klein, Martin [Physikalisches Institut Universität Heidelberg, Im Neuenheimer Feld 226, 69120 Heidelberg (Germany); Lauer, Thorsten [FRM II, TU München, Lichtenbergstraße 1, 85748 Garching (Germany); Mitsch, Kevin [Atominstitut TU Wien, Stadionallee 2, 1020 Wien (Austria); Saul, Heiko [Atominstitut TU Wien, Stadionallee 2, 1020 Wien (Austria); FRM II, TU München, Lichtenbergstraße 1, 85748 Garching (Germany); Seiler, Dominik [Physik Department, TU München, James-Franck-Straße, 85748 Garching (Germany); Stadler, David [Physikalisches Institut Universität Heidelberg, Im Neuenheimer Feld 226, 69120 Heidelberg (Germany); Thalhammer, Martin [Atominstitut TU Wien, Stadionallee 2, 1020 Wien (Austria); Abele, Hartmut, E-mail: abele@ati.ac.at [Atominstitut TU Wien, Stadionallee 2, 1020 Wien (Austria); Physikalisches Institut Universität Heidelberg, Im Neuenheimer Feld 226, 69120 Heidelberg (Germany); Physik Department, TU München, James-Franck-Straße, 85748 Garching (Germany)

    2013-12-21

    Gravity experiments with very slow, so-called ultracold neutrons connect quantum mechanics with tests of Newton's inverse square law at short distances. These experiments face a low count rate and hence need highly optimized detector concepts. In the frame of this paper, we present low-background ultracold neutron counters and track detectors with micron resolution based on a {sup 10}B converter. We discuss the optimization of {sup 10}B converter layers, detector design and concepts for read-out electronics focusing on high-efficiency and low-background. We describe modifications of the counters that allow one to detect ultracold neutrons selectively on their spin-orientation. This is required for searches of hypothetical forces with spin–mass couplings. The mentioned experiments utilize a beam-monitoring concept which accounts for variations in the neutron flux that are typical for nuclear research facilities. The converter can also be used for detectors, which feature high efficiencies paired with high spatial resolution of 1–2μm. They allow one to resolve the quantum mechanical wave function of an ultracold neutron bound in the gravity potential above a neutron mirror.

  7. Comparison of various stopping gases for {sup 3}He-based position sensitive neutron detectors

    Energy Technology Data Exchange (ETDEWEB)

    Doumas, A. [United States Merchant Marine Academy, Steamboat Road, Kings Point, NY 11024 (United States); Smith, G.C., E-mail: gsmith@bnl.gov [Instrumentation Division, Brookhaven National Laboratory, Upton, NY 11973 (United States)

    2012-05-21

    A range of solid state, scintillator and gas based detectors are being developed for use at the next generation of high flux neutron facilities. Since gas detectors are expected to continue to play a key role in future specific thermal neutron experiments, a comparison of the performance characteristics of prospective stopping gases is beneficial. Gas detectors typically utilize the reaction {sup 3}He(n,p)t to detect thermal neutrons; the {sup 3}He gas is used in a mixture containing a particular stopping gas in order to maintain relatively short ranges for the proton and triton pair emitted from the n-{sup 3}He reaction. Common stopping gases include hydrocarbons (e.g. propane), carbon tetrafluoride, and noble gases such as argon and xenon. For this study, we utilized the Monte Carlo simulation code 'Stopping and Range of Ions in Matter' to analyze the expected behavior of argon, xenon, carbon dioxide, difluoroethane and octafluoropropane as stopping gases for thermal neutron detectors. We also compare these findings to our previously analyzed performance of propane, butane and carbon tetrafluoride. A discussion of these gases includes their behavior in terms of proton and triton range, ionization distribution and straggle.

  8. Towards monolithic scintillator based TOF-PET systems: practical methods for detector calibration and operation

    Science.gov (United States)

    Borghi, Giacomo; Tabacchini, Valerio; Schaart, Dennis R.

    2016-07-01

    Gamma-ray detectors based on thick monolithic scintillator crystals can achieve spatial resolutions  NN) classification method for x,y-position estimation is accelerated with an algorithm that quickly preselects only the most useful reference events, reducing the computation time for position estimation by a factor of ~200 compared to the previously published k-NN 1D method. Also, the procedures for estimating the DOI and time of interaction are revised to enable full detector calibration by means of fan-beam or flood irradiations only. Moreover, a new technique is presented to allow the use of events in which some of the photosensor pixel values and/or timestamps are missing (e.g. due to dead time), so as to further increase system sensitivity. The accelerated methods were tested on a monolithic scintillator detector specifically developed for clinical PET applications, consisting of a 32 mm  ×  32 mm  ×  22 mm LYSO : Ce crystal coupled to a digital photon counter (DPC) array. This resulted in a spatial resolution of 1.7 mm FWHM, an average DOI resolution of 3.7 mm FWHM, and a CRT of 214 ps. Moreover, the possibility of using events missing the information of up to 16 out of 64 photosensor pixels is shown. This results in only a small deterioration of the detector performance.

  9. CdZnTe detector for computed tomography based on weighting potential

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Hyun Jong; Park, Chan Sun; Kim, Jung Su; Kim, Jung Min; Choi, Jong Hak; Kim, Ki Hyun [Korea University, Seoul (Korea, Republic of)

    2016-03-15

    Room-temperature operating CdZnTe(CZT) material is an innovative radiation detector which could reduce the patient dose to one-tenth level of conventional CT (Computed Tomography) and mammography system. The pixel and pixel pitch in the imaging device determine the conversion efficiency of incident Xor gamma-ray and the cross-talk of signal, that is, image quality of detector system. The weighting potential is the virtual potential determined by the position and geometry of electrode. The weighting potential obtained by computer-based simulation in solving Poisson equation with proper boundaries condition. The pixel was optimized by considering the CIE (charge induced efficiency) and the signal cross-talk in CT detector system. The pixel pitch was 1-mm and the detector thickness was 2-mm in the simulation. The optimized pixel size and inter-pixel distance for maximizing the CIE and minimizing the signal cross-talk is about 750 μm and 125 μm, respectively.

  10. Ultra-low threshold avalanche gain from solar-blind photodetector based on graded-band-gap-cubic-MgZnO.

    Science.gov (United States)

    Xie, Xiuhua; Zhang, Zhenzhong; Li, Binghui; Wang, Shuangpeng; Shen, Dezhen

    2015-12-14

    A larger ratio of conduction-band offset to valence-band offset is the unique character for Mg(x)Zn(1-x)O alloys. For this reason, it is feasible to build a quasi-electric forces, caused by the spatial gradient of the conduction edge, exerting on the electrons. In this paper, a novel graded band gap cubic-MgZnO-based solar-blind photodetector is successfully fabricated from Graded-Band-Gap-Cubic-MgZnO/i-MgO/p-Si heterojunction, via changing stoichiometry spatial gradient. Due to quasi-electric fields in non-uniform MgZnO, the multiple carriers are generated under ultra-low threshold bias voltage. The photodetector showed high performance, namely, high responsivity, quantum efficiency, high sensitivity and selectivity towards the solar-blind spectrum, and fast response times.

  11. Avalanche dynamics of radio pulsar glitches

    CERN Document Server

    Melatos, A; Wyithe, J S B

    2007-01-01

    We test statistically the hypothesis that radio pulsar glitches result from an avalanche process, in which angular momentum is transferred erratically from the flywheel-like superfluid in the star to the slowly decelerating, solid crust via spatially connected chains of local, impulsive, threshold-activated events, so that the system fluctuates around a self-organised critical state. Analysis of the glitch population (currently 285 events from 101 pulsars) demonstrates that the size distribution in individual pulsars is consistent with being scale invariant, as expected for an avalanche process. The waiting-time distribution is consistent with being exponential in seven out of nine pulsars where it can be measured reliably, after adjusting for observational limits on the minimum waiting time, as for a constant-rate Poisson process. PSR J0537$-$6910 and PSR J0835$-$4510 are the exceptions; their waiting-time distributions show evidence of quasiperiodicity. In each object, stationarity requires that the rate $\\...

  12. Do Neural Avalanches Indicate Criticality After All?

    CERN Document Server

    Dehghani, Mohammad; Shahbazi, Farhad

    2016-01-01

    Neural avalanches in size and duration exhibit a power law distribution illustrating as a straight line when plotted on the logarithmic scales. The power-law exponent is interpreted as the signature of criticality and it is assumed that the resting brain operates near criticality. However, there is no clear evidence that supports this assumption, and even there are extensive research studies conflicting one another. The model of the current paper is an extension of a previous publication wherein we used an integrate-and-fire model on a regular lattice with periodic boundary conditions and introduced the temporal complexity as a genuine signature of criticality. However, in that model the power-law distribution of neural avalanches were manifestation of super-criticality rather than criticality. Here, however, we show that replacing the discrete noise in the model with a Gaussian noise and continuous time solution of the equation leads to coincidence of temporal complexity and spatiotemporal patterns of neural...

  13. Snow Avalanche Release, Scale Invariance and Criticallity

    Science.gov (United States)

    Dendievel, R.; Faillettaz, J.; Daudon, D.; Louchet, F.

    It is widely recognised that a number of geophysical phenomena as volcanic eruptions, landslides, etc, obey the so-called Gutenberg-Richter relation, first established for the frequency-magnitude statistics of earthquakes, where is the occurence frequency of earthquakes with a magnitude greater than m. This power law behaviour, character- istic of critical phenomena, is usually evidenced in the form of a linear distribution in a double logarithmic plot, in a way similar to the self organised criticality of a sand pile (2). We have shown very recently and for the first time that snow avalanche release exhibited such a behaviour (3). The only reliable parameter we had at that time was the amplitude of the acoustic emission associated with the avalanche release. Since it was not possible to record several events in the same gully, data were taken in sev- eral gullys of the same mountain range. Yet, the data aligned quite well on a unique straight line, with a critical exponent of about 1.6. This observation suggests that the very nature of the release mechanism is independent of the average slope and mor- phology of the gully. In order to understand the origin of this critical behaviour and to further investigate the mechanisms responsible for avalanche release, the avalanche release is studied in the present paper both by discrete elements simulations and cel- lular automata, and compared to further field data. The discrete elements simulations deal with a population of spheres on a slope, experiencing both a gravitational stress, interactions with the substrate, and mutual contact interactions. A gradual increase of the slope or a gradual change in contact forces (accounting for thermal snow mi- crostructure evolution) eventually result in avalanche release. The conditions are ad- justed until the frequency-magnitude of avalanches exhibit a critical behaviour. The cellular automaton is more or less similar to a game of life: a 2-d grid of boxes repre- sents the

  14. Two-dimensional photon counting imaging detector based on a Vernier position sensitive anode readout

    Institute of Scientific and Technical Information of China (English)

    YAN Qiu-Rong; ZHAO Bao-Sheng; LIU Yong-An; YANG Hao; SHENG Li-Zhi; WEI Yong-Lin

    2011-01-01

    A two-dimensional photon counting imaging detector based on a Vernier position sensitive anode is reported. The decode principle and design of a two-dimensionai Vernier anode axe introduced in detail. A photon counting imaging system was built based on a Vernier anode. The image of very weak optical radiation can be reconstructed by image processing in a period of integration time. The resolution is superior to 100 μm according to the resolution test. The detector may realize the imaging of very weak particle flow of high- energy photons, electrons and ions, so it can be used for high-energy physics, deep space exploration, spectral measurement and bio-luminescence detection.

  15. Testing General Relativity with Low-Frequency, Space-Based Gravitational-Wave Detectors

    Directory of Open Access Journals (Sweden)

    John G. Baker

    2013-09-01

    Full Text Available We review the tests of general relativity that will become possible with space-based gravitational-wave detectors operating in the ∼ 10^{-5} – 1 Hz low-frequency band. The fundamental aspects of gravitation that can be tested include the presence of additional gravitational fields other than the metric; the number and tensorial nature of gravitational-wave polarization states; the velocity of propagation of gravitational waves; the binding energy and gravitational-wave radiation of binaries, and therefore the time evolution of binary inspirals; the strength and shape of the waves emitted from binary mergers and ringdowns; the true nature of astrophysical black holes; and much more. The strength of this science alone calls for the swift implementation of a space-based detector; the remarkable richness of astrophysics, astronomy, and cosmology in the low-frequency gravitational-wave band make the case even stronger.

  16. Precise measurement of first Townsend coefficient, using parallel plate avalanche chamber

    International Nuclear Information System (INIS)

    By employing iso-C4H10 gas, we have studied the effective parameters in the first Townsend coefficient measurement using parallel plate avalanche chamber (PPAC). Obtained results are free from space charge and gap deformation effects, which have seriously affected previous PPAC-based measurements. The required conditions for a reliable Townsend coefficient measurement are presented as well

  17. Basic characteristics of the avalanche transistor

    International Nuclear Information System (INIS)

    The avalanche transistor is a useful device for a short-pulse generator of the thermionic electron-gun. However, some properties of the transistor have not been clear experimentally until now. In this report the following properties are presented: the thermal characteristics of the primary breakdown voltage, variations of the output pulse waveform according to the power supply voltage, and the estimated V-I curve of the secondary breakdown voltage. (author)

  18. Artificial neural network based pulse shape analysis in cryogenic detectors for rare event searches

    International Nuclear Information System (INIS)

    We present a method based on an Artificial Neural Network for a pulse shape analysis in cryogenic detectors. To train the neural network a huge amount of pulses with known properties are necessary. Therefore, a data-driven simulation used to generate these sets is explained. Furthermore, these simulations allow detailed studies, especially of the cut efficiency and the signal purity of the developed cut. First results are presented and compared with the performance of alternative algorithms.

  19. DESIGN AND MODELLING HILBERT TRANSFORM BASED PHASE DETECTOR FOR ALL DIGITAL PHASE LOCKED LOOP

    OpenAIRE

    Anupama Patil*, Dr P.H.Tandel

    2016-01-01

    The Phase Locked Loop (PLL) is an almost always used electronics circuit for communication systems like modulator, demodulator, frequency generator and frequency synthesizer etc. All-digital phase locked loop (ADPLL) is digital version of the PLL. In this paper, a novel Hilbert transform based phase detection system for all-digital phase locked loop (ADPLL) is presented. The digital discrete time components are used to realize the phase detector system reducing the complexity of the design. T...

  20. Simulation of Portable Gamma Radiation Detectors for Virtual Reality based Training applications.

    OpenAIRE

    MOLTÓ CARACENA, TEÓFILO

    2016-01-01

    [EN] This thesis focuses on the development of a simulator of a gamma radiation portable detector. The aim is to determine the feasibility of such a software tool in a virtual reality (VR) based application, with the purpose of using it in training tasks in the framework of nuclear safeguards and security activities. The work starts with the definition of the series of technical requirements which are necessary to achieve a working prototype of an application of the kind aforementioned. ...