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Sample records for glast large area

  1. Gamma Large Area Silicon Telescope (GLAST)

    International Nuclear Information System (INIS)

    Godfrey, G.L.

    1993-11-01

    The recent discoveries and excitement generated by EGRET have prompted an investigation into modern technologies ultimately leading to the next generation space-based gamma ray telescope. The goal is to design a detector that will increase the data acquisition rate by almost two orders of magnitude beyond EGRET, while at the same time improving on the angular resolution, the energy measurement of reconstructed gamma rays, and the triggering capability of the instrument. The GLAST proposal is based on the assertion that silicon particle detectors are the technology of choice for space application: no consumables, no gas volume, robust (versus fragile), long lived, and self triggering. The GLAST detector is roughly modeled after EGRET in that a tracking module precedes a calorimeter. The GLAST Tracker has planes of thin radiatior interspersed with planes of crossed-strip (x,y) 300-μm-pitch silicon detectors to measure the coordinates of converted electron-positron pairs. The gap between the layers (∼5 cm) provides a lever arm in track fitting resulting in an angular resolution of 0.1 degree at high energy (the low energy angular resolution at 100 MeV would be about 2 degree, limited by multiple scattering). A possible GLAST calorimeter is made of a mosaic of Csl crystals of order 10 r.l. in depth, with silicon photodiodes readout. The increased depth of the GLAST calorimeter over EGRET's extends the energy range to about 300 GeV

  2. The GLAST Large Area Telescope Detector Performance Monitoring

    International Nuclear Information System (INIS)

    Borgland, A.W.; Charles, E.; SLAC

    2007-01-01

    The Large Area Telescope (LAT) is one of two instruments on board the Gamma-ray Large Area Telescope (GLAST), the next generation high energy gamma-ray space telescope. The LAT contains sixteen identical towers in a four-by-four grid. Each tower contains a silicon-strip tracker and a CsI calorimeter that together will give the incident direction and energy of the pair-converting photon in the energy range 20 MeV - 300 GeV. In addition, the instrument is covered by a finely segmented Anti-Coincidence Detector (ACD) to reject charged particle background. Altogether, the LAT contains more than 864k channels in the trackers, 1536 CsI crystals and 97 ACD plastic scintillator tiles and ribbons. Here we detail some of the strategies and methods for how we are planning to monitor the instrument performance on orbit. It builds on the extensive experience gained from Integration and Test and Commissioning of the instrument on ground

  3. GLAST, the Gamma-ray Large Area Space Telescope

    CERN Document Server

    De Angelis, A

    2001-01-01

    GLAST, a detector for cosmic gamma rays in the range from 20 MeV to 300 GeV, will be launched in space in 2005. Breakthroughs are expected in particular in the study of particle acceleration mechanisms in space and of gamma ray bursts, and maybe on the search for cold dark matter; but of course the most exciting discoveries could come from the unexpected.

  4. Gleam: the GLAST Large Area Telescope Simulation Framework

    CERN Document Server

    Boinee, P; De Angelis, Alessandro; Favretto, Dario; Frailis, Marco; Giannitrapani, Riccardo; Milotti, Edoardo; Longo, Francesco; Brigida, Monica; Gargano, Fabio; Giglietto, Nicola; Loparco, Francesco; Mazziotta, Mario Nicola; Cecchi, Claudia; Lubrano, Pasquale; Pepe, Monica; Baldini, Luca; Cohen-Tanugi, Johann; Kuss, Michael; Latronico, Luca; Omodei, Nicola; Spandre, Gloria; Bogart, Joanne R.; Dubois, Richard; Kamae, Tune; Rochester, Leon; Usher, Tracy; Burnett, Thompson H.; Robinson, Sean M.; Bastieri, Denis; Rando, Riccardo

    2003-01-01

    This paper presents the simulation of the GLAST high energy gamma-ray telescope. The simulation package, written in C++, is based on the Geant4 toolkit, and it is integrated into a general framework used to process events. A detailed simulation of the electronic signals inside Silicon detectors has been provided and it is used for the particle tracking, which is handled by a dedicated software. A unique repository for the geometrical description of the detector has been realized using the XML language and a C++ library to access this information has been designed and implemented.

  5. Conceptual Design Gamma-Ray Large Area Space Telescope (GLAST) Tower Structure

    Energy Technology Data Exchange (ETDEWEB)

    Jennings, Chad

    2002-07-18

    The main objective of this work was to develop a conceptual design and engineering prototype for the Gamma-ray Large Area Space Telescope (GLAST) tower structure. This thesis describes the conceptual design of a GLAST tower and the fabrication and testing of a prototype tower tray. The requirements were that the structure had to support GLAST's delicate silicon strip detector array through ground handling, launch and in orbit operations as well as provide for thermal and electrical pathways. From the desired function and the given launch vehicle for the spacecraft that carries the GLAST detector, an efficient structure was designed which met the requirements. This thesis developed in three stages: design, fabrication, and testing. During the first stage, a general set of specifications was used to develop the initial design, which was then analyzed and shown to meet or exceed the requirements. The second stage called for the fabrication of prototypes to prove manufacturability and gauge cost and time estimates for the total project. The last step called for testing the prototypes to show that they performed as the analysis had shown and prove that the design met the requirements. As a spacecraft engineering exercise, this project required formulating a solution based on engineering judgment, analyzing the solution using advanced engineering techniques, then proving the validity of the design and analysis by the manufacturing and testing of prototypes. The design described here met all the requirements set out by the needs of the experiment and operating concerns. This strawman design is not intended to be the complete or final design for the GLAST instrument structure, but instead examines some of the main challenges involved and demonstrates that there are solutions to them. The purpose of these tests was to prove that there are solutions to the basic mechanical, electrical and thermal problems presented with the GLAST project.

  6. Gamma Ray Large Area Space Telescope (GLAST) Balloon Flight Engineering Model: Overview

    Science.gov (United States)

    Thompson, D. J.; Godfrey, G.; Williams, S. M.; Grove, J. E.; Mizuno, T.; Sadrozinski, H. F.-W.; Kamae, T.; Ampe, J.; Briber, Stuart; Dann, James; hide

    2001-01-01

    The Gamma Ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT) is a pair-production high-energy (greater than 20 MeV) gamma-ray telescope being built by an international partnership of astrophysicists and particle physicists for a satellite launch in 2006, designed to study a wide variety of high-energy astrophysical phenomena. As part of the development effort, the collaboration has built a Balloon Flight Engineering Model (BFEM) for flight on a high-altitude scientific balloon. The BFEM is approximately the size of one of the 16 GLAST-LAT towers and contains all the components of the full instrument: plastic scintillator anticoincidence system (ACD), high-Z foil/Si strip pair-conversion tracker (TKR), CsI hodoscopic calorimeter (CAL), triggering and data acquisition electronics (DAQ), commanding system, power distribution, telemetry, real-time data display, and ground data processing system. The principal goal of the balloon flight was to demonstrate the performance of this instrument configuration under conditions similar to those expected in orbit. Results from a balloon flight from Palestine, Texas, on August 4, 2001, show that the BFEM successfully obtained gamma-ray data in this high-background environment.

  7. The Anti-Coincidence Detector for the GLAST Large Area Telescope

    Energy Technology Data Exchange (ETDEWEB)

    Moiseev, A.A.; Hartman, R.C.; Ormes, J.F.; Thompson, D.J.; Amato, M.J.; Johnson, T.E.; Segal, K.N.; Sheppard, D.A.

    2007-03-23

    This paper describes the design, fabrication and testing of the Anti-Coincidence Detector (ACD) for the Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT). The ACD is LAT's first-level defense against the charged cosmic ray background that outnumbers the gamma rays by 3-5 orders of magnitude. The ACD covers the top and 4 sides of the LAT tracking detector, requiring a total active area of {approx}8.3 square meters. The ACD detector utilizes plastic scintillator tiles with wave-length shifting fiber readout. In order to suppress self-veto by shower particles at high gamma-ray energies, the ACD is segmented into 89 tiles of different sizes. The overall ACD efficiency for detection of singly charged relativistic particles entering the tracking detector from the top or sides of the LAT exceeds the required 0.9997.

  8. GLAST

    International Nuclear Information System (INIS)

    Bloom, E.D.

    1995-01-01

    Recent results from the Energetic Gamma-Ray Experiment Telescope (EGRET) aboard the Compton Observatory have generated strong interest in space based high-energy (E γ > 10 MeV) gamma ray astronomy. This science has wetted the authors' curiosity of what might be observed with an instrument having considerably more capability than EGRET, if such a device were practical in these fiscally difficult times. Advances in silicon technology over the past decade, and the resulting rapid drop in costs, encourage the development of a dramatically new type of high-energy gamma ray space telescope based on silicon strip technology. The GLAST team (GLAST stands for Gamma-ray Large Area Space Telescope) has been working for the past two years on the design of such an instrument, and the development of the silicon strip hardware and readout electronics needed to realize this design. As in previous high-energy instruments, GLAST is a pair spectrometer backed by a total absorption electro-magnetic shower counter. Measurement of the energy and direction of the induced electro-magnetic shower provides information about the energy and direction of the incident gamma-ray. However, due to the flexibility and relatively low cost of the silicon strip technology, the telescope has about a factor of 10 increase in effective area over EGRET, and about a factor of 5 increase in field of view. At the same time, the GLAST design is calculated to have much better point source sensitivity, and to have an energy range of 10 MeV γ < 300 GeV. Due to the economics of silicon technology, along with weight, and size savings compared to gas based detector technology, the authors estimate that this instrument can be built and flown as a Delta II mission. Thus, GLAST would easily fit into the NASA intermediate category with an estimated total cost of about $200 million

  9. Gamma Large Area Silicon Telescope (GLAST): Applying silicon strip detector technology to the detection of gamma rays in space

    International Nuclear Information System (INIS)

    Atwood, W.B.

    1993-06-01

    The recent discoveries and excitement generated by space satellite experiment EGRET (presently operating on Compton Gamma Ray Observatory -- CGRO) have prompted an investigation into modern detector technologies for the next generation space based gamma ray telescopes. The GLAST proposal is based on silicon strip detectors as the open-quotes technology of choiceclose quotes for space application: no consumables, no gas volume, robust (versus fragile), long lived, and self triggerable. The GLAST detector basically has two components: a tracking module preceding a calorimeter. The tracking module has planes of crossed strip (x,y) 300 μm pitch silicon detectors coupled to a thin radiator to measure the coordinates of converted electron-positron pairs. The gap between the layers (∼5 cm) provides a lever arm for track fitting resulting in an angular resolution of <0.1 degree at high energy. The status of this R ampersand D effort is discussed including details on triggering the instrument, the organization of the detector electronics and readout, and work on computer simulations to model this instrument

  10. GLAST and AGN Science

    Science.gov (United States)

    Reyes, Luis C.

    2006-04-01

    The Large Area Telescope (LAT) on board GLAST (Gamma-ray Large Area Space Telescope) is an instrument under construction to study the gamma-ray sky in the energy range 20 MeV to >300 GeV with special interest in the previously unexplored region between a few GeV and a few hundred GeV. Among the high energy gamma-ray sources in the sky, the Blazar-class of AGNs are distinguished because of their brightness and very short term variability. GLAST's improved sensitivity with respect to previous missions will increase the number of known AGN gamma-ray sources from about 100 to thousands, with redshifts up to z>4. Science returns with GLAST include: examination of the blazar sequence model, test of leptonic and hadronic models for particle acceleration, physics of relativistic jets, and evolution of Blazar AGNs population with cosmic time. Special consideration will be given to the possibility of using the large size of the GLAST Blazar catalog to distinguish intrinsic spectra of AGNs from the redshift dependent effects of attenuation by the Extragalactic Background Light (EBL). A measured attenuation as a function of AGN redshift would constitute and effective and unique probe to the optical-UV EBL.

  11. Environmental Tests of the Flight GLAST LAT Tracker Towers

    Energy Technology Data Exchange (ETDEWEB)

    Bagagli, R.; Baldini, L.; Bellazzini, R.; Barbiellini, G.; Belli, F.; Borden, T.; Brez, A.; Brigida, M.; Caliandro, G.A.; Cecchi, C.; Cohen-Tanugi, J.; Angelis, A.De; Drell, P.; Favuzzi, C.; Fusco, P.; Gargano, F.; Germani, S.; Giglietto, N.; Giordano, F.; Goodman, J.; Himel, T.

    2008-03-12

    The Gamma-ray Large Area Space telescope (GLAST) is a gamma-ray satellite scheduled for launch in 2008. Before the assembly of the Tracker subsystem of the Large Area Telescope (LAT) science instrument of GLAST, every component (tray) and module (tower) has been subjected to extensive ground testing required to ensure successful launch and on-orbit operation. This paper describes the sequence and results of the environmental tests performed on an engineering model and all the flight hardware of the GLAST LAT Tracker. Environmental tests include vibration testing, thermal cycles and thermal-vacuum cycles of every tray and tower as well as the verification of their electrical performance.

  12. The GLAST LAT Instrument Science Operations Center

    International Nuclear Information System (INIS)

    Cameron, Robert A.; SLAC

    2007-01-01

    The Gamma-ray Large Area Space Telescope (GLAST) is scheduled for launch in late 2007. Operations support and science data processing for the Large Area Telescope (LAT) instrument on GLAST will be provided by the LAT Instrument Science Operations Center (ISOC) at the Stanford Linear Accelerator Center (SLAC). The ISOC supports GLAST mission operations in conjunction with other GLAST mission ground system elements and supports the research activities of the LAT scientific collaboration. The ISOC will be responsible for monitoring the health and safety of the LAT, preparing command loads for the LAT, maintaining embedded flight software which controls the LAT detector and data acquisition flight hardware, maintaining the operating configuration of the LAT and its calibration, and applying event reconstruction processing to down-linked LAT data to recover information about detected gamma-ray photons. The SLAC computer farm will be used to process LAT event data and generate science products, to be made available to the LAT collaboration through the ISOC and to the broader scientific community through the GLAST Science Support Center at NASA/GSFC. ISOC science operations will optimize the performance of the LAT and oversee automated science processing of LAT data to detect and monitor transient gamma-ray sources

  13. GLAST 239 Days till Launch

    CERN Multimedia

    CERN. Geneva

    2007-01-01

    The GLAST mission will open a new era in High Energy Astrophysics. GLAST will increase the available data over its predecessor, EGRET, by 2 orders of magnitude along with greatly improved image reconstruction, dead-time, and energy resolution. Vast improvements to known science and the large discovery potential are eagerly anticipated by the Astrophysics community. The current status of the mission will be detailed as well as the preparation by the GLAST Collaboration for the first observations. A few science topics as relates to fundamental physics questions will also be discussed.

  14. Serving Data to the GLAST Users Community

    International Nuclear Information System (INIS)

    Stephens, Thomas E.

    2007-01-01

    The scientific community will access the public GLAST data through the website of the GLAST Science Support Center (GSSC). For most data products the GSSC website will link to the NASA High Energy Astrophysics Science Archive Research Center's (HEASARC) Browse interface, which will actually serve the data. For example, data from the GLAST Burst Monitor (GBM) from a given burst will be packaged together and accessible through Browse. However, the photon and event data produced by the Large Area Telescope (LAT), GLAST's primary instrument, will be distributed through a custom GSSC interface. These data will be collected over the LAT's large field-of-view, usually while the LAT is scanning the sky, and thus photons from a particular direction cannot be attributed to a single 'observation' in the traditional sense. Users will request all photons detected from a region on the sky over a specified time and energy range. Through its website the GSSC will also provide long and short term science timelines, spacecraft position and attitude histories, exposure maps and other scientific data products. The different data products provided by the GSSC will be described

  15. Gamma-Ray Pulsar Studies With GLAST

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, D.J.; /NASA, Goddard

    2011-11-23

    Some pulsars have their maximum observable energy output in the gamma-ray band, offering the possibility of using these high-energy photons as probes of the particle acceleration and interaction processes in pulsar magnetospheres. After an extended hiatus between satellite missions, the recently-launched AGILE mission and the upcoming Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT) will allow gamma-ray tests of the theoretical models developed based on past discoveries. With its greatly improved sensitivity, better angular resolution, and larger energy reach than older instruments, GLAST LAT should detect dozens to hundreds of new gamma-ray pulsars and measure luminosities, light curves, and phase-resolved spectra with unprecedented resolution. It will also have the potential to find radio-quiet pulsars like Geminga, using blind search techniques. Cooperation with radio and X-ray pulsar astronomers is an important aspect of the LAT team's planning for pulsar studies.

  16. Detecting The EBL Attenuation Of Blazars With GLAST

    Science.gov (United States)

    Reyes, Luis C.

    2006-09-01

    The Large Area Telescope (LAT) on board GLAST (Gamma-ray Large Area Space Telescope) due for launch in Fall 2007 will study the gamma-ray sky in the energy range 20 MeV to >300 GeV. GLAST-LAT's improved sensitivity with respect to previous missions will increase the number of known Blazars from about 100 to thousands, with redshifts up to z 5. Since Gamma rays with energy above 10 GeV interact via pair-production with photons from the Extragalactic Background Light (EBL), the systematic attenuation of GLAST-detected Blazars as a function of redshift would constitute and effective and unique probe to the optical-UV EBL density and its evolution over cosmic history. Based on the GLAST-LAT instrument performance, detailed simulations of expected blazar populations attenuated by EBL have been performed. In this poster we present an analysis of such simulations in order to measure the EBL attenuation, ensuing a clear distinction between competing EBL models.

  17. The GLAST silicon-strip tracking system

    International Nuclear Information System (INIS)

    Johnson, Robert P.

    2000-01-01

    The GLAST instrument concept is a gamma-ray pair conversion telescope that uses silicon microstrip detector technology to track the electron-positron pairs resulting from gamma-ray conversions in thin lead foils. A cesium iodide calorimeter following the tracker is used to measure the gamma-ray energy. Silicon strip technology is mature and robust, with an excellent heritage in space science and particle physics. It has many characteristics important for optimal performance of a pair conversion telescope, including high efficiency in thin detector planes, low noise, and excellent resolution and two-track separation. The large size of GLAST and high channel count in the tracker puts demands on the readout technology to operate at very low power, yet with sufficiently low noise occupancy to allow self triggering. A prototype system employing custom-designed ASIC's has been built and tested that meets the design goal of approximately 200 W per channel power consumption with a noise occupancy of less than one hit per trigger per 10,000 channels. Detailed design of the full-scale tracker is well advanced, with non-flight prototypes built for all components, and a complete 50,000 channel engineering demonstration tower module is currently under construction and will be tested in particle beams in late 1999. The flight-instrument conceptual design is for a 4x4 array of tower modules with an aperture of 2.9 m2 and an effective area of greater than 8000 cm2

  18. The GLAST Silicon-Strip Tracking System

    International Nuclear Information System (INIS)

    Johnson, R

    2004-01-01

    The GLAST instrument concept is a gamma-ray pair conversion telescope that uses silicon microstrip detector technology to track the electron-positron pairs resulting from gamma ray conversions in thin lead foils. A cesium iodide calorimeter following the tracker is used to measure the gamma-ray energy. Silicon strip technology is mature and robust, with an excellent heritage in space science and particle physics. It has many characteristics important for optimal performance of a pair conversion telescope, including high efficiency in thin detector planes, low noise, and excellent resolution and two-track separation. The large size of GLAST and high channel count in the tracker puts demands on the readout technology to operate at very low power, yet with sufficiently low noise occupancy to allow self triggering. A prototype system employing custom-designed ASIC's has been built and tested that meets the design goal of approximately 200 (micro)W per channel power consumption with a noise occupancy of less than one hit per trigger per 10,000 channels. Detailed design of the full-scale tracker is well advanced, with non-flight prototypes built for all components, and a complete 50,000 channel engineering demonstration tower module is currently under construction and will be tested in particle beams in late 1999. The flight-instrument conceptual design is for a 4 x 4 array of tower modules with an aperture of 2.9 m 2 and an effective area of greater than 8000 cm 2

  19. Definition of a Twelve-Point Polygonal SAA Boundary for the GLAST Mission

    International Nuclear Information System (INIS)

    Djomehri, Sabra I.; UC, Santa Cruz; SLAC

    2007-01-01

    The Gamma-Ray Large Area Space Telescope (GLAST), set to launch in early 2008, detects gamma rays within a huge energy range of 100 MeV - 300 GeV. Background cosmic radiation interferes with such detection resulting in confusion over distinguishing cosmic from gamma rays encountered. This quandary is resolved by encasing GLAST's Large Area Telescope (LAT) with an Anti-Coincidence Detector (ACD), a device which identifies and vetoes charged particles. The ACD accomplishes this through plastic scintillator tiles; when cosmic rays strike, photons produced induce currents in Photomultiplier Tubes (PMTs) attached to these tiles. However, as GLAST orbits Earth at altitudes ∼550km and latitudes between -26 degree and 26 degree, it will confront the South Atlantic Anomaly (SAA), a region of high particle flux caused by trapped radiation in the geomagnetic field. Since the SAA flux would degrade the sensitivity of the ACD's PMTs over time, a determined boundary enclosing this region need be attained, signaling when to lower the voltage on the PMTs as a protective measure. The operational constraints on such a boundary require a convex SAA polygon with twelve edges, whose area is minimal ensuring GLAST has maximum observation time. The AP8 and PSB97 models describing the behavior of trapped radiation were used in analyzing the SAA and defining a convex SAA boundary of twelve sides. The smallest possible boundary was found to cover 14.58% of GLAST's observation time. Further analysis of defining a boundary safety margin to account for inaccuracies in the models reveals if the total SAA hull area is increased by ∼20%, the loss of total observational area is < 5%. These twelve coordinates defining the SAA flux region are ready for implementation by the GLAST satellite

  20. Preliminary results from the GLAST silicon tracker beam test

    Energy Technology Data Exchange (ETDEWEB)

    Germani, Stefano [INFN sez.Perugia, Via A. Pascoli, 06123, Perugia (Italy)], E-mail: stefano.germani@pg.infn.it

    2007-12-01

    The Large Area Telescope (LAT) on board the Gamma-ray Large Area Space Telescope (GLAST) is a pair-conversion gamma-ray detector designed to explore the gamma-ray universe in the 20 MeV-300 GeV energy band. The Tracker subsystem of the LAT will perform tracking of electrons and positrons to determine the origin of the gamma-ray. The LAT instrument, the Calibration Unit (CU) and the beamtest performed at CERN during the summer 2006 are described in this paper.

  1. Preliminary Results From the GLAST Silicon Tracker Beam Test

    Energy Technology Data Exchange (ETDEWEB)

    Germani, Stefano; /INFN, Perugia

    2009-05-12

    The Large Area Telescope (LAT) on board the Gamma-ray Large Area Space Telescope (GLAST) is a pair-conversion gamma-ray detector designed to explore the gamma-ray universe in the 20 MeV-300 GeV energy band. The Tracker subsystem of the LAT will perform tracking of electrons and positrons to determine the origin of the gamma-ray. The LAT instrument, the Calibration Unit (CU) and the beamtest performed at CERN during the summer 2006 are described in this paper.

  2. GLAST and Suzaku. Study on cosmic-ray acceleration and interaction in the cosmos

    International Nuclear Information System (INIS)

    Kamae, Tuneyoshi

    2007-01-01

    The Gamma-Ray Large Area Space Telescope (GLAST) is an international and multi-agency mission scheduled for launch in the fall of 2007. The Large Area Telescope (LAT), the primary instrument of the mission, will survey the high energy sky found to be very dynamic and surprisingly diverse by its predecessor the Energetic Gamma Ray Experiment Telescope (EGRET). GLAST-LAT will have a much improved sensitivity when compared with EGRET and extend the higher energy coverage to ∼300 GeV. The instrument is now mounted on the spacecraft and undergoing a suite of pre-flight tests. Data analysis software has been tried out by collaborators in two rounds of 'Data Challenges' using simulated observations including backgrounds. The instrument performance and observational data on selected sources presented here have been obtained through the Data Challenges in the collaborative efforts. There are features in the GLAST-LAT observation possibly unfamiliar to X-ray astronomers: 1) GLAST will operate mostly in the survey mode; 2) the foreground objects (gas, dust, and star-light) become gamma-ray sources; 3) multiple sources will be 'confused' because of the wide point-spread-function. The last two features will pose a challenge for analysis on extended Galactic sources such as supernova remnants and pulsar wind nebulae: multi-wavelength study with X-ray instruments like Suzaku and atmospheric Chrenkov telescopes will become essential to dig out the underlying physics. (author)

  3. THE ORIGIN OF COSMIC RAYS: WHAT CAN GLAST SAY?

    Energy Technology Data Exchange (ETDEWEB)

    Bloom, Elliott

    2000-10-10

    Gamma rays in the band from 30 MeV to 300 GeV, used in combination with direct measurements and with data from radio and X-ray bands, provide a powerful tool for studying the origin of Galactic cosmic rays. Gamma-ray Large Area Space Telescope (GLAST) with its fine 10-20 arcmin angular resolution will be able to map the sites of acceleration of cosmic rays and their interactions with interstellar matter. It will provide information that is necessary to study the acceleration of energetic particles in supernova shocks, their transport in the interstellar medium and penetration into molecular clouds.

  4. Correlative Spectral Analysis of Gamma-Ray Bursts using Swift-BAT and GLAST-GBM

    International Nuclear Information System (INIS)

    Stamatikos, Michael; Sakamoto, Taka; Band, David L.

    2008-01-01

    We discuss the preliminary results of spectral analysis simulations involving anticipated correlated multi-wavelength observations of gamma-ray bursts (GRBs) using Swift's Burst Alert Telescope (BAT) and the Gamma-Ray Large Area Space Telescope's (GLAST) Burst Monitor (GLAST-GBM), resulting in joint spectral fits, including characteristic photon energy (E peak ) values, for a conservative annual estimate of ∼30 GRBs. The addition of BAT's spectral response will (i) complement in-orbit calibration efforts of GBM's detector response matrices, (ii) augment GLAST's low energy sensitivity by increasing the ∼20-100 keV effective area, (iii) facilitate ground-based follow-up efforts of GLAST GRBs by increasing GBM's source localization precision, and (iv) help identify a subset of non-triggered GRBs discovered via off-line GBM data analysis. Such multi-wavelength correlative analyses, which have been demonstrated by successful joint-spectral fits of Swift-BAT GRBs with other higher energy detectors such as Konus-WIND and Suzaku-WAM, would enable the study of broad-band spectral and temporal evolution of prompt GRB emission over three energy decades, thus potentially increasing science return without placing additional demands upon mission resources throughout their contemporaneous orbital tenure over the next decade.

  5. Correlative Spectral Analysis of Gamma-Ray Bursts using Swift-BAT and GLAST-GBM

    International Nuclear Information System (INIS)

    Stamatikos, Michael; Sakamoto, Takanori; Band, David L.

    2008-01-01

    We discuss the preliminary results of spectral analysis simulations involving anticipated correlated multi-wavelength observations of gamma-ray bursts (GRBs) using Swift's Burst Alert Telescope (BAT) and the Gamma-Ray Large Area Space Telescope's (GLAST) Burst Monitor (GLAST-GBM), resulting in joint spectral fits, including characteristic photon energy (E peak ) values, for a conservative annual estimate of ∼30 GRBs. The addition of BAT/s spectral response will (i) complement in-orbit calibration efforts of GBM's detector response matrices, (ii) augment GLAST's low energy sensitivity by increasing the ∼20-100 keV effective area, (iii) facilitate ground-based follow-up efforts of GLAST GRBs by increasing GBM's source localization precision, and (iv) help identify a subset of non-triggered GRBs discovered via off-line GBM data analysis. Such multi-wavelength correlative analyses, which have been demonstrated by successful joint-spectral fits of Swift-BAT GRBs with other higher energy detectors such as Konus-WIND and Suzaku-WAM, would enable the study of broad-band spectral and temporal evolution of prompt GRB emission over three energy decades, thus potentially increasing science return without placing additional demands upon mission resources throughout their contemporaneous orbital tenure over the next decade

  6. GLAST beam test at SLAC

    International Nuclear Information System (INIS)

    Engovatov, D.; Anthony, P.; Atwood, W.

    1996-10-01

    In May and June, a beam test for GLAST calorimeter technologies was conducted. A parasitic low intensity electron/tagged photon beam line into the End Station A at SLAC was commissioned and used. The preliminary stage of the test was devoted to measuring the performance of the parasitic beam. In the main test we studied the response of GLAST prototype CsI and scintillating fiber calorimeters to the electrons and photons. Results of this work are discussed

  7. The GLAST Mission, LAT and GRBs

    International Nuclear Information System (INIS)

    Omodei, Nicola; INFN, Pisa

    2006-01-01

    The GLAST Large Area Telescope (LAT) is the next generation satellite experiment for high-energy gamma-ray astronomy. It is a pair conversion telescope built with a plastic anticoincidence shield, a segmented CsI electromagnetic calorimeter, and the largest silicon strip tracker ever built. It will cover the energy range from 30 MeV to 300 GeV, shedding light on many issues left open by its predecessor EGRET. One of the most exciting science topics is the detection and observation of gamma-ray bursts (GRBs). In this paper we present the work done so far by the GRB LAT science group in studying the performance of the LAT detector to observe GRBs.We report on the simulation framework developed by the group as well as on the science tools dedicated to GRBs data analysis. We present the LAT sensitivity to GRBs obtained with such simulations, and, finally, the general scheme of GRBs detection that will be adopted on orbit

  8. The Status of GLAST CsI Calorimeter

    Energy Technology Data Exchange (ETDEWEB)

    Chekhtman, A.

    2003-09-18

    GLAST is a gamma-ray observatory for celestial sources in the energy range from 20 MeV to 300 GeV. This is NASA project with launch anticipated in 2006. The principal instrument of the GLAST mission is the Large Area Telescope (LAT), consisting of an Anti Coincidence Detector (ACD), a silicon-strip detector Tracker (TKR) and a hodoscopic CsI Calorimeter (CAL). It consists of 16 identical modules arranged in a 4 x 4 array. Each module has horizontal dimensions 38 x 38 cm{sup 2} and active thickness 8.5 radiation length. It contains 96 CsI (Tl) crystals arranged in 8 layers with 12 crystals per layer. The scintillation light is measured by PIN photodiodes mounted on both ends of each crystal. The sum of signals at the two ends of the crystal provides the energy measurement. The difference in these signals provides the position measurement along the crystal. The calorimeter was designed to meet the goals of good energy resolution (better than 10% for photon energies 100 MeV-100 GeV), position resolution of {approx} 1 mm for photon energies > 1 GeV, and a rejection factor of > 100 for charged cosmic rays, under limitations on calorimeter weight (95 kg per module) and power consumption (6 W per module). The Monte Carlo simulation and prototype beam test results confirm that proposed design meets the requirements. Calorimeter production is planned to start in 2003.

  9. Response of the GLAST LAT calorimeter to relativistic heavy ions

    International Nuclear Information System (INIS)

    Lott, B.; Piron, F.; Blank, B.; Bogaert, G.; Bregeon, J.; Canchel, G.; Chekhtman, A.; D'Avezac, P.; Dumora, D.; Giovinazzo, J.; Grove, J.E.; Hellstroem, M.; Jacholkowska, A.; Johnson, W.N.; Nuss, E.; Reposeur, Th.; Smith, D.A.; Suemmerer, K.

    2006-01-01

    The CsI calorimeter of the Gamma-Ray Large-Area Space Telescope (GLAST) will be calibrated in flight with cosmic-ray heavy ions. In order to determine the response of the calorimeter to relativistic heavy ions lighter than Fe, an experiment was carried out at the GSI heavy ion facility using the Fragment Separator (FRS). The measured response exhibits an unexpected feature for light ions, opposite to that observed at low incident energy: for a given deposited energy, the observed signal is greater for these ions than for protons (or more generally Z=1 minimum ionizing particles). Pulse shapes are found to be almost identical for carbon ions and Z=1 particles, with a significant slow scintillation component, which constitutes another departure from the low-energy behavior. Data on the energy resolution for the individual CsI crystals and on the loss of ions due to nuclear reactions in the calorimeter are also presented

  10. The assembly of the silicon tracker for the GLAST beam test engineering model

    International Nuclear Information System (INIS)

    Allport, P.; Atwood, E.; Atwood, W.; Beck, G.; Bhatnager, B.; Bloom, E.; Broeder, J.; Chen, V.; Clark, J.; Cotton, N.; Couto e Silva, E. do; Feerick, B.; Giebels, G.; Godfrey, G.; Handa, T.; Hernando, J.A.; Hirayama, M.; Johnson, R.P.; Kamae, T.; Kashiguine, S.; Kroeger, W.; Milbury, C.; Miller, W.; Millican, O.; Nikolaou, M.; Nordby, M.; Ohsugi, T.; Paliaga, G.; Ponslet, E.; Rowe, W.; Sadrozinski, H.F.-W.; Spencer, E.; Stromberg, S.; Swensen, E.; Takayuki, M.; Tournear, D.; Webster, A.; Winkler, G.; Yamamoto, K.; Yamamura, K.; Yoshida, S.

    2001-01-01

    The silicon tracker for the engineering model of the GLAST Large Area Telescope (LAT) to date represents the largest surface of silicon microstrip detectors assembled in a tracker (2.7 m 2 ). It demonstrates the feasibility of employing this technology for satellite based experiments, in which large effective areas and high reliability are required. This note gives an overview of the assembly of this silicon tracker and discusses in detail studies performed to track quality assurance: leakage current, mechanical alignment and production yields

  11. Search for GLAST gamma ray burst triggers due to particle precipitation in the South Atlantic Anomaly

    International Nuclear Information System (INIS)

    Augusto, C. R. A.; Navia, C. E.; Tsui, K. H.

    2008-01-01

    When GLAST is in the South Atlantic Anomaly (SAA), the rate of charged particles is too high to be efficiently filtered out. Moreover the high rate can cause saturation effects in the readout electronics and the sensors must be turned off. The SAA area relative to the total area of GLAST's orbit is approximately 12.5% and GLAST spends 18% of the time in it. In spite of these cares, we show in this work that, due to drift processes, particle precipitation can still trigger GLAST when it is close to the SAA region. Here, we report two GLAST gamma ray burst monitor (GBM) triggers, trigger 239895229 and trigger 239913100, on August, 08, 2008 whose characteristics are similar to the ones observed in the Swift-BAT noise triggers (due to particle precipitation in the SAA region). Both GLAST triggers happened during a plentiful particle precipitation in the SAA region, observed by Tupi telescopes at the ground with their trigger coordinates close to the field of view of the telescopes. Details of these results are reported.

  12. Analysis of Burst Observations by GLAST's LAT Detector

    International Nuclear Information System (INIS)

    Band, David L.; Digel, Seth W.

    2004-01-01

    Analyzing data from GLAST's Large Area Telescope (LAT) will require sophisticated techniques. The PSF and effective area are functions of both photon energy and the position in the field-of-view. During most of the mission the observatory will survey the sky continuously, and thus, the LAT will detect each count from a source at a different detector orientation; each count requires its own response function! The likelihood as a function of celestial position and photon energy will be the foundation of the standard analysis techniques. However, the 20 MeV-300 GeV emission at the time of the ∼ 100 keV burst emission (timescale of ∼ 10 s) can be isolated and analyzed because essentially no non-burst counts are expected within a PSF radius of the burst location during the burst. Both binned and unbinned (in energy) spectral fitting will be possible. Longer timescale afterglow emission will require the likelihood analysis that will be used for persistent sources

  13. Construction, Test And Calibration of the GLAST Silicon Tracker

    Energy Technology Data Exchange (ETDEWEB)

    Sgro, C.; Atwood, W.B.; Baldini, L.; Barbiellini, G.; Bellazzini, R.; Belli, F.; Bonamente, E.; Borden, T.; Bregeon, J.; Brez, A.; Brigida, M.; Caliandro, G.A.; Cecchi, C.; Cohen-Tanugi, J.; De Angelis, A.; Drell, P.; Favuzzi, C.; Fukazawa, Y.; Fusco, P.; Gargano, F.; Germani, S.; /INFN, Pisa /Pisa U. /UC, Santa Cruz /INFN, Trieste /Rome U.,Tor Vergata /SLAC /INFN, Bari /Bari U. /INFN, Perugia /Perugia U. /Udine U. /Hiroshima U. /Maryland U., JCA /Tokyo Inst. Tech. /JAXA, Sagamihara /INFN, Padua /Padua U. /Pisa, Scuola Normale Superiore /NASA, Goddard

    2009-06-05

    The Gamma-ray Large Area Space Telescope represents a great advance in space application of silicon detectors. With a surface of 80 m{sup 2} and about 1 M readout channels it is the largest silicon tracker ever built for a space experiment. GLAST is an astro-particle mission that will study the mostly unexplored, high energy (20 MeV-300 GeV) spectrum coming from active sources or diffused in the Universe. The detector integration and test phase is complete. The full instrument underwent environmental testing and the spacecraft integration phase has just started: the launch is foreseen in late 2007. In the meanwhile the spare modules are being used for instrument calibration and performance verification employing the CERN accelerator complex. A Calibration Unit has been exposed to photon, electron and hadron beams from a few GeV up to 300 GeV. We report on the status of the instrument and on the calibration campaign.

  14. Large area bulk superconductors

    Science.gov (United States)

    Miller, Dean J.; Field, Michael B.

    2002-01-01

    A bulk superconductor having a thickness of not less than about 100 microns is carried by a polycrystalline textured substrate having misorientation angles at the surface thereof not greater than about 15.degree.; the bulk superconductor may have a thickness of not less than about 100 microns and a surface area of not less than about 50 cm.sup.2. The textured substrate may have a thickness not less than about 10 microns and misorientation angles at the surface thereof not greater than about 15.degree.. Also disclosed is a process of manufacturing the bulk superconductor and the polycrystalline biaxially textured substrate material.

  15. XML for Detector Description at GLAST

    Energy Technology Data Exchange (ETDEWEB)

    Bogart, Joanne

    2002-04-30

    The problem of representing a detector in a form which is accessible to a variety of applications, allows retrieval of information in ways which are natural to those applications, and is maintainable has been vexing physicists for some time. Although invented to address an entirely different problem domain, the document markup meta-language XML is well-suited to detector description. This paper describes its use for a GLAST detector.

  16. XML for detector description at GLAST

    International Nuclear Information System (INIS)

    Bogart, J.; Favretto, D.; Giannitrapani, R.

    2001-01-01

    The problem of representing a detector in a form which is accessible to a variety of applications, allows retrieval of information in ways which are natural to those applications, and is maintainable has been vexing physicists for some time. Although invented to address an entirely different problem domain, the document markup meta-language XML is well-suited to detector description. The author describes its use for a GLAST detector

  17. XML for Detector Description at GLAST

    International Nuclear Information System (INIS)

    Bogart, Joanne

    2002-01-01

    The problem of representing a detector in a form which is accessible to a variety of applications, allows retrieval of information in ways which are natural to those applications, and is maintainable has been vexing physicists for some time. Although invented to address an entirely different problem domain, the document markup meta-language XML is well-suited to detector description. This paper describes its use for a GLAST detector

  18. Large area and flexible electronics

    CERN Document Server

    Caironi, Mario

    2015-01-01

    From materials to applications, this ready reference covers the entire value chain from fundamentals via processing right up to devices, presenting different approaches to large-area electronics, thus enabling readers to compare materials, properties and performance.Divided into two parts, the first focuses on the materials used for the electronic functionality, covering organic and inorganic semiconductors, including vacuum and solution-processed metal-oxide semiconductors, nanomembranes and nanocrystals, as well as conductors and insulators. The second part reviews the devices and applicatio

  19. Large-area photonic crystals

    Science.gov (United States)

    Ruhl, Tilmann; Spahn, Peter; Hellmann, Gotz P.; Winkler, Holger

    2004-09-01

    Materials with a periodically modulated refractive index, with periods on the scale of light wavelengths, are currently attracting much attention because of their unique optical properties which are caused by Bragg scattering of the visible light. In nature, 3d structures of this kind are found in the form of opals in which monodisperse silica spheres with submicron diameters form a face-centered-cubic (fcc) lattice. Artificial opals, with the same colloidal-crystalline fcc structure, have meanwhile been prepared by crystallizing spherical colloidal particles via sedimentation or drying of dispersions. In this report, colloidal crystalline films are introduced that were produced by a novel technique based on shear flow in the melts of specially designed submicroscopic silica-polymer core-shell hybrid spheres: when the melt of these spheres flows between the plates of a press, the spheres crystallize along the plates, layer by layer, and the silica cores assume the hexagonal order corresponding to the (111) plane of the fcc lattice. This process is fast and yields large-area films, thin or thick. To enhance the refractive index contrast in these films, the colloidal crystalline structure was inverted by etching out the silica cores with hydrofluoric acid. This type of an inverse opal, in which the fcc lattice is formed by mesopores, is referred to as a polymer-air photonic crystal.

  20. Large area CMOS image sensors

    International Nuclear Information System (INIS)

    Turchetta, R; Guerrini, N; Sedgwick, I

    2011-01-01

    CMOS image sensors, also known as CMOS Active Pixel Sensors (APS) or Monolithic Active Pixel Sensors (MAPS), are today the dominant imaging devices. They are omnipresent in our daily life, as image sensors in cellular phones, web cams, digital cameras, ... In these applications, the pixels can be very small, in the micron range, and the sensors themselves tend to be limited in size. However, many scientific applications, like particle or X-ray detection, require large format, often with large pixels, as well as other specific performance, like low noise, radiation hardness or very fast readout. The sensors are also required to be sensitive to a broad spectrum of radiation: photons from the silicon cut-off in the IR down to UV and X- and gamma-rays through the visible spectrum as well as charged particles. This requirement calls for modifications to the substrate to be introduced to provide optimized sensitivity. This paper will review existing CMOS image sensors, whose size can be as large as a single CMOS wafer, and analyse the technical requirements and specific challenges of large format CMOS image sensors.

  1. LYCORIS - A Large Area Strip Telescope

    CERN Document Server

    Krämer, U; Stanitzki, M; Wu, M

    2018-01-01

    The LYCORIS Large Area Silicon Strip Telescope for the DESY II Test Beam Facility is presented. The DESY II Test Beam Facility provides elec- tron and positron beams for beam tests of up to 6 GeV. A new telescope with a large 10 × 20 cm2 coverage area based on a 25 μm pitch strip sensor is to be installed within the PCMAG 1 T solenoid. The current state of the system is presented.

  2. The European Large Area ISO Survey

    DEFF Research Database (Denmark)

    Oliver, S.; Rowan-Robinson, M.; Alexander, D.M.

    2000-01-01

    We describe the European Large Area ISO Survey (ELAIS). ELAIS was the largest single Open Time project conducted by ISO, mapping an area of 12 deg(2) at 15 mu m with ISOCAM and at 90 mu m with ISOPHOT. Secondary surveys in other ISO bands were undertaken by the ELAIS team within the fields of the...

  3. Large area damage testing of optics

    International Nuclear Information System (INIS)

    Sheehan, L.; Kozlowski, M.; Stolz, C.

    1996-01-01

    The damage threshold specifications for the National Ignition Facility will include a mixture of standard small-area tests and new large-area tests. During our studies of laser damage and conditioning processes of various materials we have found that some damage morphologies are fairly small and this damage does not grow with further illumination. This type of damage might not be detrimental to the laser performance. We should therefore assume that some damage can be allowed on the optics, but decide on a maximum damage allowance of damage. A new specification of damage threshold termed open-quotes functional damage thresholdclose quotes was derived. Further correlation of damage size and type to system performance must be determined in order to use this measurement, but it is clear that it will be a large factor in the optics performance specifications. Large-area tests have verified that small-area testing is not always sufficient when the optic in question has defect-initiated damage. This was evident for example on sputtered polarizer and mirror coatings where the defect density was low enough that the features could be missed by standard small- area testing. For some materials, the scale-length at which damage non-uniformities occur will effect the comparison of small-area and large-area tests. An example of this was the sub-aperture tests on KD*P crystals on the Beamlet test station. The tests verified the large-area damage threshold to be similar to that found when testing a small-area. Implying that for this KD*P material, the dominate damage mechanism is of sufficiently small scale-length that small-area testing is capable of determining the threshold. The Beamlet test station experiments also demonstrated the use of on-line laser conditioning to increase the crystals damage threshold

  4. Large Area Sputter Coating on Glass

    Science.gov (United States)

    Katayama, Yoshihito

    Large glass has been used for commercial buildings, housings and vehicles for many years. Glass size for flat displays is getting larger and larger. The glass for the 8th generation is more than 5 m2 in area. Demand of the large glass is increasing not only in these markets but also in a solar cell market growing drastically. Therefore, large area coating is demanded to plus something else on glass more than ever. Sputtering and pyrolysis are the major coating methods on large glass today. Sputtering process is particularly popular because it can deposit a wide variety of materials in good coating uniformity on the glass. This paper describes typical industrial sputtering system and recent progress in sputtering technology. It also shows typical coated glass products in architectural, automotive and display fields and comments on their functions, film stacks and so on.

  5. Large catchment area recharges Titan's Ontario Lacus

    Science.gov (United States)

    Dhingra, Rajani D.; Barnes, Jason W.; Yanites, Brian J.; Kirk, Randolph L.

    2018-01-01

    We seek to address the question of what processes are at work to fill Ontario Lacus while other, deeper south polar basins remain empty. Our hydrological analysis indicates that Ontario Lacus has a catchment area spanning 5.5% of Titan's surface and a large catchment area to lake surface area ratio. This large catchment area translates into large volumes of liquid making their way to Ontario Lacus after rainfall. The areal extent of the catchment extends to at least southern mid-latitudes (40°S). Mass conservation calculations indicate that runoff alone might completely fill Ontario Lacus within less than half a Titan year (1 Titan year = 29.5 Earth years) assuming no infiltration. Cassini Visual and Infrared Mapping Spectrometer (VIMS) observations of clouds over the southern mid and high-latitudes are consistent with precipitation feeding Ontario's large catchment area. This far-flung rain may be keeping Ontario Lacus filled, making it a liquid hydrocarbon oasis in the relatively dry south polar region.

  6. Design and Initial Tests of the Tracker-Converter ofthe Gamma-ray Large Area Space Telescope

    Energy Technology Data Exchange (ETDEWEB)

    Atwood, W.B.; Bagagli, R.; Baldini, L.; Bellazzini, R.; Barbiellini, G.; Belli, F.; Borden, T.; Brez, A.; Brigida, M.; Caliandro, G.A.; Cecchi, C.; Cohen-Tanugi, J.; De; Drell, P.; Favuzzi, C.; Fukazawa, Y.; Fusco, P.; Gargano, F.; Germani, S.; Giannitrapani, R.; Giglietto, N.; /UC, Santa Cruz /INFN, Pisa /Pisa U. /INFN, Trieste /INFN,

    2007-04-16

    The Tracker subsystem of the Large Area Telescope (LAT) science instrument of the Gamma-ray Large Area Space Telescope (GLAST) mission has been completed and tested. It is the central detector subsystem of the LAT and serves both to convert an incident gamma-ray into an electron-positron pair and to track the pair in order to measure the gamma-ray direction. It also provides the principal trigger for the LAT. The Tracker uses silicon strip detectors, read out by custom electronics, to detect charged particles. The detectors and electronics are packaged, along with tungsten converter foils, in 16 modular, high-precision carbon-composite structures. It is the largest silicon-strip detector system ever built for launch into space, and its aggressive design emphasizes very low power consumption, passive cooling, low noise, high efficiency, minimal dead area, and a structure that is highly transparent to charged particles. The test program has demonstrated that the system meets or surpasses all of its performance specifications as well as environmental requirements. It is now installed in the completed LAT, which is being prepared for launch in early 2008.

  7. Quantitative Mapping of Large Area Graphene Conductance

    DEFF Research Database (Denmark)

    Buron, Jonas Christian Due; Petersen, Dirch Hjorth; Bøggild, Peter

    2012-01-01

    We present quantitative mapping of large area graphene conductance by terahertz time-domain spectroscopy and micro four point probe. We observe a clear correlation between the techniques and identify the observed systematic differences to be directly related to imperfections of the graphene sheet...

  8. Stability of large-area molecular junctions

    NARCIS (Netherlands)

    Akkerman, Hylke B.; Kronemeijer, Auke J.; Harkema, Jan; van Hal, Paul A.; Smits, Edsger C. P.; de Leeuw, Dago M.; Blom, Paul W. M.

    The stability of molecular junctions is crucial for any application of molecular electronics. Degradation of molecular junctions when exposed to ambient conditions is regularly observed. In this report the stability of large-area molecular junctions under ambient conditions for more than two years

  9. A large area plastic Cherenkov detector

    International Nuclear Information System (INIS)

    Bernabei, R.; Bidoli, V.; Zorzi, G. de; Biagio, A. di

    1978-01-01

    A large area Cherenkov counter has been built up using as a radiator a sheet of Pilot 425 plastic, (180x20)cm 2 x2.5 cm. Experimental tests performed with a pion beam in order to measure the average number of photoelectrons collected by photomultipliers and the scintillation to Cherenkov light ratio. (Auth.)

  10. Noise Pulses in Large Area Optical Modules

    International Nuclear Information System (INIS)

    Aiello, Sebastiano; Leonora, Emanuele; Giordano, Valentina

    2013-06-01

    A great number of large area photomultipliers are widely used in neutrino and astro-particle detector to measure Cherenkov light in medium like water or ice. The key element of these detectors are the so-called 'optical module', which consist in photodetectors closed in a transparent pressure-resistant container to protect it and ensure good light transmission. The noise pulses present on the anode of each photomultiplier affect strongly the performance of the detector. A large study was conducted on noise pulses of large area photomultipliers, considering time and charge distributions of dark pulses, prepulses, delayed pulses, and after pulses. The contribution to noise pulses due to the presence of the external glass spheres was also studied, even comparing two vessels of different brands. (authors)

  11. Progress on large area GEMs (VCI 2010)

    CERN Document Server

    Villa, Marco; Alfonsi, Matteo; Brock, Ian; Croci, Gabriele; David, Eric; de Oliveira, Rui; Ropelewski, Leszek; Taureg, Hans; van Stenis, Miranda

    2011-01-01

    The Gas Electron Multiplier (GEM) manufacturing technique has recently evolved to allow the production of large area GEMs. A novel approach based on single mask photolithography eliminates the mask alignment issue, which limits the dimensions in the traditional double mask process. Moreover, a splicing technique overcomes the limited width of the raw material. Stretching and handling issues in large area GEMs have also been addressed. Using the new improvements it was possible to build a prototype triple-GEM detector of ~ 2000 cm2 active area, aimed at an application for the TOTEM T1 upgrade. Further refinements of the single mask technique give great control over the shape of the GEM holes and the size of the rims, which can be tuned as needed. In this framework, simulation studies can help to understand the GEM behavior depending on the hole shape.

  12. Chemical Vapour Deposition of Large Area Graphene

    DEFF Research Database (Denmark)

    Larsen, Martin Benjamin Barbour Spanget

    Chemical Vapor Deposition (CVD) is a viable technique for fabrication of large areas of graphene. CVD fabrication is the most prominent and common way of fabricating graphene in industry. In this thesis I have attempted to optimize a growth recipe and catalyst layer for CVD fabrication of uniform......, single layer, and high carrier mobility large area graphene. The main goals of this work are; (1) explore the graphene growth mechanics in a low pressure cold-wall CVD system on a copper substrate, and (2) optimize the process of growing high quality graphene in terms of carrier mobility, and crystal...... structure. Optimization of a process for graphene growth on commercially available copper foil is limited by the number of aluminium oxide particles on the surface of the catalyst. By replacing the copper foil with a thin deposited copper film on a SiO2/Si or c-plane sapphire wafer the particles can...

  13. Pulsed Gamma-Rays From PSR J2021 3651 with the Fermi Large Area Telescope

    International Nuclear Information System (INIS)

    Abdo, Aous A.; Ackermann, M.; Ajello, Marco; Atwood, William B.; Baldini, L.; Ballet, J.; Barbiellini, Guido; Bastieri, Denis; Battelino, Milan; Baughman, B.M.; Bechtol, K.; Bellazzini, Ronaldo; Berenji, Bijan; Bloom, Elliott D.; Bogaert, G.; Borgland, Anders W.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Burnett, Thompson H.

    2009-01-01

    We report the detection of pulsed gamma-rays from the young, spin-powered radio pulsar PSR J2021+3651 using data acquired with the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope (formerly GLAST). The light curve consists of two narrow peaks of similar amplitude separated by 0.468 ± 0.002 in phase. The first peak lags the maximum of the 2 GHz radio pulse by 0.162 ± 0.004 ± 0.01 in phase. The integral gamma-ray photon flux above 100 MeV is (56 ± 3 ± 11) x 10 -8 cm -2 s -1 . The photon spectrum is well-described by an exponentially cut-off power law of the form dF/dE = kE -# Gamma#e (-E/E c ) where the energy E is expressed in GeV. The photon index is Γ = 1.5 ± 0.1 ± 0.1 and the exponential cut-off is E c = 2.4 ± 0.3 ± 0.5 GeV. The first uncertainty is statistical and the second is systematic. The integral photon flux of the bridge is approximately 10% of the pulsed emission, and the upper limit on off-pulse gamma-ray emission from a putative pulsar wind nebula is -2 but a poorly constrained magnetic geometry. Re-analysis of Chandra data enhanced the significance of the weak X-ray pulsations, and the first peak is roughly phase-aligned with the first gamma-ray peak. We discuss the emission region and beaming geometry based on the shape and spectrum of the gamma-ray light curve combined with radio and X-ray measurements, and the implications for the pulsar distance. Gamma-ray emission from the polar cap region seems unlikely for this pulsar.

  14. Very large area multiwire spectroscopic proportional counters

    International Nuclear Information System (INIS)

    Ubertini, P.; Bazzano, A.; Boccaccini, L.; Mastropietro, M.; La Padula, C.D.; Patriarca, R.; Polcaro, V.F.

    1981-01-01

    As a result of a five year development program, a final prototype of a Very Large Area Spectroscopic Proportional Counter (VLASPC), to be employed in space borne payloads, was produced at the Istituto di Astrofisica Spaziale, Frascati. The instrument is the last version of a new generation of Multiwire Spectroscopic Proportional Counters (MWSPC) succesfully employed in many balloon borne flights, devoted to hard X-ray astronomy. The sensitive area of this standard unit is 2700 cm 2 with an efficiency higher than 10% in the range 15-180 keV (80% at 60 keV). The low cost and weight make this new type of VLASPC competitive with Nal arrays, phoswich and GSPC detectors in terms of achievable scientific results. (orig.)

  15. Very large area multiwire spectroscopic proportional counters

    Energy Technology Data Exchange (ETDEWEB)

    Ubertini, P.; Bazzano, A.; Boccaccini, L.; Mastropietro, M.; La Padula, C.D.; Patriarca, R.; Polcaro, V.F. (Istituto di Astrofisica Spaziale, Frascati (Italy))

    1981-07-01

    As a result of a five year development program, a final prototype of a Very Large Area Spectroscopic Proportional Counter (VLASPC), to be employed in space borne payloads, was produced at the Istituto di Astrofisica Spaziale, Frascati. The instrument is the last version of a new generation of Multiwire Spectroscopic Proportional Counters (MWSPC) successfully employed in many balloon borne flights, devoted to hard X-ray astronomy. The sensitive area of this standard unit is 2700 cm/sup 2/ with an efficiency higher than 10% in the range 15-180 keV (80% at 60 keV). The low cost and weight make this new type of VLASPC competitive with Nal arrays, phoswich and GSPC detectors in terms of achievable scientific results.

  16. Supernova Remnants with Fermi Large Area Telescope

    Directory of Open Access Journals (Sweden)

    Caragiulo M.

    2017-01-01

    Full Text Available The Large Area Telescope (LAT, on-board the Fermi satellite, proved to be, after 8 years of data taking, an excellent instrument to detect and observe Supernova Remnants (SNRs in a range of energies running from few hundred MeV up to few hundred GeV. It provides essential information on physical processes that occur at the source, involving both accelerated leptons and hadrons, in order to understand the mechanisms responsible for the primary Cosmic Ray (CR acceleration. We show the latest results in the observation of Galactic SNRs by Fermi-LAT.

  17. Large area solid target neutron source

    International Nuclear Information System (INIS)

    Crawford, J.C.; Bauer, W.

    1974-01-01

    A potentially useful neutron source may result from the combination of a solid deuterium-tritium loaded target with the large area, high energy ion beams from ion sources being developed for neutral beam injection. The resulting neutron source would have a large radiating area and thus produce the sizable experimental volume necessary for future studies of bulk and synergistic surface radiation effects as well as experiments on engineering samples and small components. With a 200 keV D + T + beam and 40 kW/cm 2 power dissipation on a 200 cm 2 target spot, a total neutron yield of about 4 x 10 15 n/sec may be achieved. Although the useable neutron flux from this source is limited to 1 to 2 x 10 13 n/cm 2 /sec, this flux can be produced 3 cm in front of the target and over about 300 cm 3 of experimental volume. Problems of total power dissipation, sputtering, isotopic flushing and thermal dissociation are reviewed. Neutron flux profiles and potential experimental configurations are presented and compared to other neutron source concepts. (U.S.)

  18. Charge reconstruction in large-area photomultipliers

    Science.gov (United States)

    Grassi, M.; Montuschi, M.; Baldoncini, M.; Mantovani, F.; Ricci, B.; Andronico, G.; Antonelli, V.; Bellato, M.; Bernieri, E.; Brigatti, A.; Brugnera, R.; Budano, A.; Buscemi, M.; Bussino, S.; Caruso, R.; Chiesa, D.; Corti, D.; Dal Corso, F.; Ding, X. F.; Dusini, S.; Fabbri, A.; Fiorentini, G.; Ford, R.; Formozov, A.; Galet, G.; Garfagnini, A.; Giammarchi, M.; Giaz, A.; Insolia, A.; Isocrate, R.; Lippi, I.; Longhitano, F.; Lo Presti, D.; Lombardi, P.; Marini, F.; Mari, S. M.; Martellini, C.; Meroni, E.; Mezzetto, M.; Miramonti, L.; Monforte, S.; Nastasi, M.; Ortica, F.; Paoloni, A.; Parmeggiano, S.; Pedretti, D.; Pelliccia, N.; Pompilio, R.; Previtali, E.; Ranucci, G.; Re, A. C.; Romani, A.; Saggese, P.; Salamanna, G.; Sawy, F. H.; Settanta, G.; Sisti, M.; Sirignano, C.; Spinetti, M.; Stanco, L.; Strati, V.; Verde, G.; Votano, L.

    2018-02-01

    Large-area PhotoMultiplier Tubes (PMT) allow to efficiently instrument Liquid Scintillator (LS) neutrino detectors, where large target masses are pivotal to compensate for neutrinos' extremely elusive nature. Depending on the detector light yield, several scintillation photons stemming from the same neutrino interaction are likely to hit a single PMT in a few tens/hundreds of nanoseconds, resulting in several photoelectrons (PEs) to pile-up at the PMT anode. In such scenario, the signal generated by each PE is entangled to the others, and an accurate PMT charge reconstruction becomes challenging. This manuscript describes an experimental method able to address the PMT charge reconstruction in the case of large PE pile-up, providing an unbiased charge estimator at the permille level up to 15 detected PEs. The method is based on a signal filtering technique (Wiener filter) which suppresses the noise due to both PMT and readout electronics, and on a Fourier-based deconvolution able to minimize the influence of signal distortions—such as an overshoot. The analysis of simulated PMT waveforms shows that the slope of a linear regression modeling the relation between reconstructed and true charge values improves from 0.769 ± 0.001 (without deconvolution) to 0.989 ± 0.001 (with deconvolution), where unitary slope implies perfect reconstruction. A C++ implementation of the charge reconstruction algorithm is available online at [1].

  19. Large area electron beam diode development

    International Nuclear Information System (INIS)

    Helava, H.; Gilman, C.M.; Stringfield, R.M.; Young, T.

    1983-01-01

    A large area annular electron beam diode has been tested at Physics International Co. on the multi-terawatt PITHON generator. A twelve element post hole convolute converted the coaxial MITL into a triaxial arrangement of anode current return structures both inside and outside the cathode structure. The presence of both inner and outer current return paths provide magnetic pressure balance for the beam, as determined by diode current measurements. X-ray pinhole photographs indicated uniform emission with intensity maxima between the post positions. Current losses in the post hole region were negligible, as evidenced by the absence of damage to the aluminum hardware. Radial electron flow near the cathode ring however did damage the inner anode cylinder between the post positions. Cutting away these regions prevented further damage of the transmission lines

  20. Large-area mapping of biodiversity

    Science.gov (United States)

    Scott, J.M.; Jennings, M.D.

    1998-01-01

    The age of discovery, description, and classification of biodiversity is entering a new phase. In responding to the conservation imperative, we can now supplement the essential work of systematics with spatially explicit information on species and assemblages of species. This is possible because of recent conceptual, technical, and organizational progress in generating synoptic views of the earth's surface and a great deal of its biological content, at multiple scales of thematic as well as geographic resolution. The development of extensive spatial data on species distributions and vegetation types provides us with a framework for: (a) assessing what we know and where we know it at meso-scales, and (b) stratifying the biological universe so that higher-resolution surveys can be more efficiently implemented, coveting, for example, geographic adequacy of specimen collections, population abundance, reproductive success, and genetic dynamics. The land areas involved are very large, and the questions, such as resolution, scale, classification, and accuracy, are complex. In this paper, we provide examples from the United States Gap Analysis Program on the advantages and limitations of mapping the occurrence of terrestrial vertebrate species and dominant land-cover types over large areas as joint ventures and in multi-organizational partnerships, and how these cooperative efforts can be designed to implement results from data development and analyses as on-the-ground actions. Clearly, new frameworks for thinking about biogeographic information as well as organizational cooperation are needed if we are to have any hope of documenting the full range of species occurrences and ecological processes in ways meaningful to their management. The Gap Analysis experience provides one model for achieving these new frameworks.

  1. Instrument Response Modeling and Simulation for the GLAST Burst Monitor

    International Nuclear Information System (INIS)

    Kippen, R. M.; Hoover, A. S.; Wallace, M. S.; Pendleton, G. N.; Meegan, C. A.; Fishman, G. J.; Wilson-Hodge, C. A.; Kouveliotou, C.; Lichti, G. G.; Kienlin, A. von; Steinle, H.; Diehl, R.; Greiner, J.; Preece, R. D.; Connaughton, V.; Briggs, M. S.; Paciesas, W. S.; Bhat, P. N.

    2007-01-01

    The GLAST Burst Monitor (GBM) is designed to provide wide field of view observations of gamma-ray bursts and other fast transient sources in the energy range 10 keV to 30 MeV. The GBM is composed of several unshielded and uncollimated scintillation detectors (twelve NaI and two BGO) that are widely dispersed about the GLAST spacecraft. As a result, reconstructing source locations, energy spectra, and temporal properties from GBM data requires detailed knowledge of the detectors' response to both direct radiation as well as that scattered from the spacecraft and Earth's atmosphere. This full GBM instrument response will be captured in the form of a response function database that is derived from computer modeling and simulation. The simulation system is based on the GEANT4 Monte Carlo radiation transport simulation toolset, and is being extensively validated against calibrated experimental GBM data. We discuss the architecture of the GBM simulation and modeling system and describe how its products will be used for analysis of observed GBM data. Companion papers describe the status of validating the system

  2. Electromagnetic surface waves for large-area RF plasma productions between large-area planar electrodes

    International Nuclear Information System (INIS)

    Nonaka, S.

    1992-01-01

    Recently, large-area plasma production has been tested by means of a 13.56 MHz radio-frequency (RF) discharge between a pair of large-area planar electrodes, approximately 0.5 m x 1.4 m, as one of the semiconductor technologies for fabrication of large-area amorphous silicon solar cells in the ''Sunshine Project'' of the Agency of Industrial Science and Technology in Japan. We also confirmed long plasma production between a pair of long electrodes. In this paper, normal electromagnetic (EM) waves propagating in a region between a planar waveguide with one plasma and two dielectric layers are analyzed in order to study the feasibility of large-area plasma productions by EM wave-discharges between a pair of large-area RF electrodes larger than the half-wavelength of RF wave. In conclusion, plasmas higher than an electron plasma frequency will be produced by an odd TMoo surface mode. (author) 4 refs., 3 figs

  3. Large area atmospheric-pressure plasma jet

    Science.gov (United States)

    Selwyn, Gary S.; Henins, Ivars; Babayan, Steve E.; Hicks, Robert F.

    2001-01-01

    Large area atmospheric-pressure plasma jet. A plasma discharge that can be operated at atmospheric pressure and near room temperature using 13.56 MHz rf power is described. Unlike plasma torches, the discharge produces a gas-phase effluent no hotter than 250.degree. C. at an applied power of about 300 W, and shows distinct non-thermal characteristics. In the simplest design, two planar, parallel electrodes are employed to generate a plasma in the volume therebetween. A "jet" of long-lived metastable and reactive species that are capable of rapidly cleaning or etching metals and other materials is generated which extends up to 8 in. beyond the open end of the electrodes. Films and coatings may also be removed by these species. Arcing is prevented in the apparatus by using gas mixtures containing He, which limits ionization, by using high flow velocities, and by properly spacing the rf-powered electrode. Because of the atmospheric pressure operation, there is a negligible density of ions surviving for a sufficiently long distance beyond the active plasma discharge to bombard a workpiece, unlike the situation for low-pressure plasma sources and conventional plasma processing methods.

  4. FERMI LARGE AREA TELESCOPE FIRST SOURCE CATALOG

    International Nuclear Information System (INIS)

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Allafort, A.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Antolini, E.; Bonamente, E.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Bellazzini, R.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bisello, D.; Baughman, B. M.; Belli, F.

    2010-01-01

    We present a catalog of high-energy gamma-ray sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi), during the first 11 months of the science phase of the mission, which began on 2008 August 4. The First Fermi-LAT catalog (1FGL) contains 1451 sources detected and characterized in the 100 MeV to 100 GeV range. Source detection was based on the average flux over the 11 month period, and the threshold likelihood Test Statistic is 25, corresponding to a significance of just over 4σ. The 1FGL catalog includes source location regions, defined in terms of elliptical fits to the 95% confidence regions and power-law spectral fits as well as flux measurements in five energy bands for each source. In addition, monthly light curves are provided. Using a protocol defined before launch we have tested for several populations of gamma-ray sources among the sources in the catalog. For individual LAT-detected sources we provide firm identifications or plausible associations with sources in other astronomical catalogs. Identifications are based on correlated variability with counterparts at other wavelengths, or on spin or orbital periodicity. For the catalogs and association criteria that we have selected, 630 of the sources are unassociated. Care was taken to characterize the sensitivity of the results to the model of interstellar diffuse gamma-ray emission used to model the bright foreground, with the result that 161 sources at low Galactic latitudes and toward bright local interstellar clouds are flagged as having properties that are strongly dependent on the model or as potentially being due to incorrectly modeled structure in the Galactic diffuse emission.

  5. Massive stars in colliding wind systems: the GLAST perspective

    International Nuclear Information System (INIS)

    Reimer, Anita; Reimer, Olaf

    2007-01-01

    Colliding winds of massive stars in binary systems arc considered as candidate sites of high-energy non-thermal photon emission. They are already among the suggested counterparts for a few individual unidentified EGRET sources, but may constitute a detectable source population for the GLAST observatory.The present work investigates such population study of massive colliding wind systems at high-energy gamma-rays. Based on the recent detailed model (Reimer et al. 2006) for non-thermal photon production in prime candidate systems, we unveil the expected characteristics of this source class in the observables accessible at LAT energies. Combining the broadband emission model with the presently cataloged distribution of such systems and their individual parameters allows us to conclude on the expected maximum number of LAT-detections among massive stars in colliding wind binary systems

  6. ISABELLE. Volume 3. Experimental areas, large detectors

    International Nuclear Information System (INIS)

    1981-01-01

    This section presents the papers which resulted from work in the Experimental Areas portion of the Workshop. The immediate task of the group was to address three topics. The topics were dictated by the present state of ISABELLE experimental areas construction, the possibility of a phased ISABELLE and trends in physics and detectors

  7. Preserving Medieval Farm Mounds in a Large Stormwater Retention Area

    NARCIS (Netherlands)

    Vorenhout, M.

    2016-01-01

    The Netherlands has denoted large areas as stormwater retention areas. These areas function as temporary storage locations for stormwater when rivers cannot cope with the amount of water. A large area, the Onlanden — 2,500 hectares — was developed as such a storage area between 2008 and 2013. This

  8. Pulsed Gamma-Rays From PSR J2021 3651 with the Fermi Large Area Telescope

    Energy Technology Data Exchange (ETDEWEB)

    Abdo, Aous A.; /Naval Research Lab, Wash., D.C.; Ackermann, M.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Ajello, Marco; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Atwood, William B.; /UC, Santa Cruz; Baldini, L.; /INFN, Pisa; Ballet, J.; /DAPNIA, Saclay; Barbiellini, Guido; /INFN, Trieste /Trieste U.; Bastieri, Denis; /INFN, Padua /Padua U.; Battelino, Milan; /Royal Inst. Tech., Stockholm; Baughman, B.M.; /Ohio State U.; Bechtol, K.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bellazzini, Ronaldo; /INFN, Pisa; Berenji, Bijan; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bloom, Elliott D.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bogaert, G.; /Ecole Polytechnique; Borgland, Anders W.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bregeon, J.; /INFN, Pisa; Brez, A.; /INFN, Pisa; Brigida, M.; /Bari U. /INFN, Bari; Bruel, P.; /Ecole Polytechnique; Burnett, Thompson H.; /Washington U., Seattle /Bari U. /INFN, Bari /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Columbia U. /IASF, Milan /IASF, Milan /DAPNIA, Saclay /INFN, Perugia /Perugia U. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /George Mason U. /Naval Research Lab, Wash., D.C. /IASF, Milan /IASF, Milan /NASA, Goddard /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /INFN, Perugia /Perugia U. /LPCE, Orleans /Montpellier U. /Sonoma State U. /Royal Inst. Tech., Stockholm /Stockholm U. /ASI, Rome /NRAO, Charlottesville /Naval Research Lab, Wash., D.C. /INFN, Trieste /Pavia U. /Bari U. /INFN, Bari /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /UC, Santa Cruz /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /CENBG, Gradignan /CENBG, Gradignan /Manchester U. /Montpellier U. /Bari U. /INFN, Bari; /more authors..

    2011-11-30

    We report the detection of pulsed gamma-rays from the young, spin-powered radio pulsar PSR J2021+3651 using data acquired with the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope (formerly GLAST). The light curve consists of two narrow peaks of similar amplitude separated by 0.468 {+-} 0.002 in phase. The first peak lags the maximum of the 2 GHz radio pulse by 0.162 {+-} 0.004 {+-} 0.01 in phase. The integral gamma-ray photon flux above 100 MeV is (56 {+-} 3 {+-} 11) x 10{sup -8} cm{sup -2} s{sup -1}. The photon spectrum is well-described by an exponentially cut-off power law of the form dF/dE = kE{sup -{Gamma}}e{sup (-E/E{sub c})} where the energy E is expressed in GeV. The photon index is {Gamma} = 1.5 {+-} 0.1 {+-} 0.1 and the exponential cut-off is E{sub c} = 2.4 {+-} 0.3 {+-} 0.5 GeV. The first uncertainty is statistical and the second is systematic. The integral photon flux of the bridge is approximately 10% of the pulsed emission, and the upper limit on off-pulse gamma-ray emission from a putative pulsar wind nebula is < 10% of the pulsed emission at the 95% confidence level. Radio polarization measurements yield a rotation measure of RM = 524 {+-} 4 rad m{sup -2} but a poorly constrained magnetic geometry. Re-analysis of Chandra data enhanced the significance of the weak X-ray pulsations, and the first peak is roughly phase-aligned with the first gamma-ray peak. We discuss the emission region and beaming geometry based on the shape and spectrum of the gamma-ray light curve combined with radio and X-ray measurements, and the implications for the pulsar distance. Gamma-ray emission from the polar cap region seems unlikely for this pulsar.

  9. Pulsed Gamma-Rays From the Millisecond Pulsar J0030+0451 with the Fermi Large Area Telescope

    International Nuclear Information System (INIS)

    Abdo, Aous A.; Ackermann, M.; Atwood, W.B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, Guido; Bastieri, Denis; Battelino, M.; Baughman, B.M.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bloom, Elliott D.; Bonamente, E.; Borgland, A.W.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Burnett, Thompson H.

    2009-01-01

    We report the discovery of gamma-ray pulsations from the nearby isolated millisecond pulsar PSR J0030+0451 with the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope (formerly GLAST). This discovery makes PSR J0030+0451 the second millisecond pulsar to be detected in gamma-rays after PSR J0218+4232, observed by the EGRET instrument on the Compton Gamma Ray Observatory. The spin-down power (dot E) = 3.5 x 10 33 ergs s -1 is an order of magnitude lower than the empirical lower bound of previously known gamma-ray pulsars. The emission profile is characterized by two narrow peaks, respectively 0.07 ± 0.01 and 0.08 ± 0.02 wide, separated by 0.44 ± 0.02 in phase. The first gamma-ray peak falls 0.15 ± 0.01 after the main radio peak. The pulse shape is similar to that of the 'normal' gamma-ray pulsars. An exponentially cut-off power-law fit of the emission spectrum leads to an integral photon flux above 100 MeV of (6.76 ± 1.05 ± 1.35) x 10 -8 cm -2 s -1 with cut-off energy (1.7 ± 0.4 ± 0.5) GeV. Based on its parallax distance of (300 ± 90) pc, we obtain a gamma-ray efficiency L γ /(dot E) ≅ 15% for the conversion of spin-down energy rate into gamma-ray radiation, assuming isotropic emission.

  10. PULSED GAMMA RAYS FROM THE MILLISECOND PULSAR J0030+0451 WITH THE FERMI LARGE AREA TELESCOPE

    International Nuclear Information System (INIS)

    Abdo, A. A.; Ackermann, M.; Bechtol, K.; Berenji, B.; Bloom, E. D.; Borgland, A. W.; Atwood, W. B.; Axelsson, M.; Battelino, M.; Baldini, L.; Bellazzini, R.; Bregeon, J.; Brez, A.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Baughman, B. M.; Bonamente, E.; Brigida, M.; Bruel, P.

    2009-01-01

    We report the discovery of gamma-ray pulsations from the nearby isolated millisecond pulsar (MSP) PSR J0030+0451 with the Large Area Telescope on the Fermi Gamma-ray Space Telescope (formerly GLAST). This discovery makes PSR J0030+0451 the second MSP to be detected in gamma rays after PSR J0218+4232, observed by the EGRET instrument on the Compton Gamma-Ray Observatory. The spin-down power E-dot=3.5x10 33 erg s -1 is an order of magnitude lower than the empirical lower bound of previously known gamma-ray pulsars. The emission profile is characterized by two narrow peaks, 0.07 ± 0.01 and 0.08 ± 0.02 wide, respectively, separated by 0.44 ± 0.02 in phase. The first gamma-ray peak falls 0.15 ± 0.01 after the main radio peak. The pulse shape is similar to that of the 'normal' gamma-ray pulsars. An exponentially cutoff power-law fit of the emission spectrum leads to an integral photon flux above 100 MeV of (6.76 ± 1.05 ± 1.35) x 10 -8 cm -2 s -1 with cutoff energy (1.7 ± 0.4 ± 0.5) GeV. Based on its parallax distance of (300 ± 90) pc, we obtain a gamma-ray efficiency L γ /E-dot≅15 percent for the conversion of spin-down energy rate into gamma-ray radiation, assuming isotropic emission.

  11. Pulsed Gamma-Rays From the Millisecond Pulsar J0030+0451 with the Fermi Large Area Telescope

    Energy Technology Data Exchange (ETDEWEB)

    Abdo, Aous A.; /Naval Research Lab, Wash., D.C.; Ackermann, M.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Atwood, W.B.; /UC, Santa Cruz; Axelsson, M. /Stockholm U., OKC /Stockholm U.; Baldini, L.; /INFN, Pisa; Ballet, J.; /DAPNIA, Saclay; Barbiellini, Guido; /INFN, Trieste /Trieste U.; Bastieri, Denis; /INFN, Padua /Padua U.; Battelino, M.; /Stockholm U., OKC /Royal Inst. Tech., Stockholm; Baughman, B.M.; /Ohio State U.; Bechtol, K.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bellazzini, R.; /INFN, Pisa; Berenji, B.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bloom, Elliott D.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bonamente, E.; /INFN, Perugia /Perugia U.; Borgland, A.W.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bregeon, J.; /INFN, Pisa; Brez, A.; /INFN, Pisa; Brigida, M.; /Bari U. /INFN, Bari; Bruel, P.; /Ecole Polytechnique; Burnett, Thompson H.; /Washington U., Seattle /Bari U. /INFN, Bari /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /IASF, Milan /IASF, Milan /DAPNIA, Saclay /INFN, Perugia /Perugia U. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /George Mason U. /Naval Research Lab, Wash., D.C. /NASA, Goddard /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /INFN, Perugia /Perugia U. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /LPCE, Orleans /Montpellier U. /Sonoma State U. /Stockholm U., OKC /Royal Inst. Tech., Stockholm /Stockholm U. /ASDC, Frascati /Naval Research Lab, Wash., D.C. /INFN, Trieste /Bari U. /INFN, Bari /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /UC, Santa Cruz /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /CENBG, Gradignan /CENBG, Gradignan /Montpellier U. /Bari U. /INFN, Bari /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /INFN, Trieste /Hiroshima U.; /more authors..

    2011-11-17

    We report the discovery of gamma-ray pulsations from the nearby isolated millisecond pulsar PSR J0030+0451 with the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope (formerly GLAST). This discovery makes PSR J0030+0451 the second millisecond pulsar to be detected in gamma-rays after PSR J0218+4232, observed by the EGRET instrument on the Compton Gamma Ray Observatory. The spin-down power {dot E} = 3.5 x 10{sup 33} ergs s{sup -1} is an order of magnitude lower than the empirical lower bound of previously known gamma-ray pulsars. The emission profile is characterized by two narrow peaks, respectively 0.07 {+-} 0.01 and 0.08 {+-} 0.02 wide, separated by 0.44 {+-} 0.02 in phase. The first gamma-ray peak falls 0.15 {+-} 0.01 after the main radio peak. The pulse shape is similar to that of the 'normal' gamma-ray pulsars. An exponentially cut-off power-law fit of the emission spectrum leads to an integral photon flux above 100 MeV of (6.76 {+-} 1.05 {+-} 1.35) x 10{sup -8} cm{sup -2} s{sup -1} with cut-off energy (1.7 {+-} 0.4 {+-} 0.5) GeV. Based on its parallax distance of (300 {+-} 90) pc, we obtain a gamma-ray efficiency L{sub {gamma}}/{dot E} {approx_equal} 15% for the conversion of spin-down energy rate into gamma-ray radiation, assuming isotropic emission.

  12. Reduced alcohol intake and reward associated with impaired endocannabinoid signaling in mice with a deletion of the glutamate transporter GLAST

    DEFF Research Database (Denmark)

    Karlsson, Rose-Marie; Adermark, Louise; Molander, Anna

    2012-01-01

    mice with a deletion of GLAST to test this prediction. WT and GLAST KO mice were tested for alcohol consumption using two-bottle free-choice drinking. Alcohol reward was evaluated using conditioned place preference (CPP). Sensitivity to depressant alcohol effects was tested using the accelerating...... rotarod, alcohol-induced hypothermia, and loss of righting reflex. Extracellular glutamate was measured using microdialysis, and striatal slice electrophysiology was carried out to examine plasticity of the cortico-striatal pathway as a model system in which adaptations to the constitutive GLAST deletion...... deletion of GLAST unexpectedly results in markedly reduced alcohol consumption and preference, associated with markedly reduced alcohol reward. Endocannabinoid signaling appears to be down-regulated upstream of the CB1 receptor as a result of the GLAST deletion, and is a candidate mechanism behind...

  13. Fabrication of the GLAST Silicon Tracker Readout Electronics

    Energy Technology Data Exchange (ETDEWEB)

    Baldini, Luca; Brez, Alessandro; Himel, Thomas; Johnson, R.P.; Latronico, Luca; Minuti, Massimo; Nelson, David; Sadrozinski, H.F.-W.; Sgro, Carmelo; Spandre, Gloria; Sugizaki, Mutsumi; Tajima, Hiro; Cohen Tanugi, Johann; Young, Charles; Ziegler, Marcus; /Pisa U. /INFN, Pisa /SLAC /UC, Santa Cruz

    2006-03-03

    A unique electronics system has been built and tested for reading signals from the silicon-strip detectors of the Gamma-ray Large Area Space Telescope mission. The system amplifies and processes signals from 884,736 36-cm long silicon strips in a 4 x 4 array of tower modules. An aggressive mechanical design fits the readout electronics in narrow spaces between the tower modules, to minimize dead area. This design and the resulting departures from conventional electronics packaging led to several fabrication challenges and lessons learned. This paper describes the fabrication processes and how the problems peculiar to this design were overcome.

  14. Large-Area Visually Augmented Navigation for Autonomous Underwater Vehicles

    National Research Council Canada - National Science Library

    Eustice, Ryan M

    2005-01-01

    ...., unstructured terrain, low-overlap imagery, moving light source). Our large area SLAM algorithm recursively incorporates relative-pose constraints using a view-based representation that exploits exact sparsity in the Gaussian canonical...

  15. Diagnose of large area electron beam with faraday cup

    International Nuclear Information System (INIS)

    Tang Ying; Qian Hang; Yi Aiping; Huang Xin; Yu Li; Liu Jingru; Su Jiancang; Ding Zhenjie; Ding Yongzhong; Yu Jianguo

    2008-01-01

    In the experiment of gas laser pumped by electron beam, large area uniform electron beam is important to generate high efficiency laser output. This paper introduces Faraday cup is used in the diagnose experiment on the uniformity of large area e-beam generated by SPG-200 pulsed power generator. Construction of Faraday cup and the results of calibration are presented in detail. The uniformity of velvet emission is given, and the results of experiment are analyzed. (authors)

  16. Optimization of magnetic field system for glass spherical tokamak GLAST-III

    International Nuclear Information System (INIS)

    Ahmad, Zahoor; Ahmad, S; Naveed, M A; Deeba, F; Javeed, M Aqib; Batool, S; Hussain, S; Vorobyov, G M

    2017-01-01

    GLAST-III (Glass Spherical Tokamak) is a spherical tokamak with aspect ratio A = 2. The mapping of its magnetic system is performed to optimize the GLAST-III tokamak for plasma initiation using a Hall probe. Magnetic field from toroidal coils shows 1/ R dependence which is typical with spherical tokamaks. Toroidal field (TF) coils can produce 875 Gauss field, an essential requirement for electron cyclotron resonance assisted discharge. The central solenoid (CS) of GLAST-III is an air core solenoid and requires compensation coils to reduce unnecessary magnetic flux inside the vessel region. The vertical component of magnetic field from the CS in the vacuum vessel region is reduced to 1.15 Gauss kA −1 with the help of a differential loop. The CS of GLAST can produce flux change up to 68 mVs. Theoretical and experimental results are compared for the current waveform of TF coils using a combination of fast and slow capacitor banks. Also the magnetic field produced by poloidal field (PF) coils is compared with theoretically predicted values. It is found that calculated results are in good agreement with experimental measurement. Consequently magnetic field measurements are validated. A tokamak discharge with 2 kA plasma current and pulse length 1 ms is successfully produced using different sets of coils. (paper)

  17. Spatially explicit shallow landslide susceptibility mapping over large areas

    Science.gov (United States)

    Dino Bellugi; William E. Dietrich; Jonathan Stock; Jim McKean; Brian Kazian; Paul Hargrove

    2011-01-01

    Recent advances in downscaling climate model precipitation predictions now yield spatially explicit patterns of rainfall that could be used to estimate shallow landslide susceptibility over large areas. In California, the United States Geological Survey is exploring community emergency response to the possible effects of a very large simulated storm event and to do so...

  18. Large area modules based on low band gap polymers

    DEFF Research Database (Denmark)

    Bundgaard, Eva; Krebs, Frederik C

    2010-01-01

    The use of three low band gap polymers in large area roll-to-roll coated modules is demonstrated. The polymers were prepared by a Stille cross coupling polymerization and all had a band gap around 1.6 eV. The polymers were first tested in small area organic photovoltaic devices which showed...

  19. Pneumatic radiator of transition radiation for large working area arrangements

    International Nuclear Information System (INIS)

    Shikhlyarov, K.K.; Gavalyan, V.G.

    1993-01-01

    An unconventional approach to the constructions of large area regular radiator of X-rays transition radiation is proposed based on the use of a pack of hermetically sealed bags, in which elastic helium layers are formed. A prototype of such a radiator of about 1m 2 area was made for test of the proposed device. 9 refs

  20. Seafloor mapping of large areas using multibeam system - Indian experience

    Digital Repository Service at National Institute of Oceanography (India)

    Kodagali, V.N.; KameshRaju, K.A; Ramprasad, T.

    averaged and merged to produce large area maps. Maps were generated in the scale of 1 mil. and 1.5 mil covering area of about 2 mil. sq.km in single map. Also, depth contour interval were generated. A computer program was developed to convert the depth data...

  1. Large-area OLED lightings and their applications

    International Nuclear Information System (INIS)

    Park, J W; Shin, D C; Park, S H

    2011-01-01

    In this paper, we review the key issues related to the fabrication of large-area organic light-emitting devices (OLEDs) for lighting applications. We discuss the origin of a short-circuit problem, luminance non-uniformity, hot spot, efficiency reduction (power loss), and heat generation and present the way of suppressing them. We also introduce three different application areas of large-area OLED lighting panels. They can be integrated with a solar cell for power recycling or inorganic LEDs for emotional lightings. The feasibility of using OLEDs for the application of visible-light communications is also reviewed

  2. Mapping the electrical properties of large-area graphene

    DEFF Research Database (Denmark)

    Bøggild, Peter; Mackenzie, David; Whelan, Patrick Rebsdorf

    2017-01-01

    The significant progress in terms of fabricating large-area graphene films for transparent electrodes, barriers, electronics, telecommunication and other applications has not yet been accompanied by efficient methods for characterizing the electrical properties of large-area graphene. While......, and a high measurement effort per device. In this topical review, we provide a comprehensive overview of the issues that need to be addressed by any large-area characterisation method for electrical key performance indicators, with emphasis on electrical uniformity and on how this can be used to provide...... a more accurate analysis of the graphene film. We review and compare three different, but complementary approaches that rely either on fixed contacts (dry laser lithography), movable contacts (micro four point probes) and non-contact (terahertz time-domain spectroscopy) between the probe and the graphene...

  3. Optical fabrication of large area photonic microstructures by spliced lens

    Science.gov (United States)

    Jin, Wentao; Song, Meng; Zhang, Xuehua; Yin, Li; Li, Hong; Li, Lin

    2018-05-01

    We experimentally demonstrate a convenient approach to fabricate large area photorefractive photonic microstructures by a spliced lens device. Large area two-dimensional photonic microstructures are optically induced inside an iron-doped lithium niobate crystal. The experimental setups of our method are relatively compact and stable without complex alignment devices. It can be operated in almost any optical laboratories. We analyze the induced triangular lattice microstructures by plane wave guiding, far-field diffraction pattern imaging and Brillouin-zone spectroscopy. By designing the spliced lens appropriately, the method can be easily extended to fabricate other complex large area photonic microstructures, such as quasicrystal microstructures. Induced photonic microstructures can be fixed or erased and re-recorded in the photorefractive crystal.

  4. Plasma and Ion Sources in Large Area Coatings: A Review

    Energy Technology Data Exchange (ETDEWEB)

    Anders, Andre

    2005-02-28

    Efficient deposition of high-quality coatings often requires controlled application of excited or ionized particles. These particles are either condensing (film-forming) or assisting by providing energy and momentum to the film growth process, resulting in densification, sputtering/etching, modification of stress, roughness, texture, etc. In this review, the technical means are surveyed enabling large area application of ions and plasmas, with ion energies ranging from a few eV to a few keV. Both semiconductortype large area (single wafer or batch processing with {approx} 1000 cm{sup 2}) and in-line web and glass-coating-type large area (> 10{sup 7} m{sup 2} annually) are considered. Characteristics and differences between plasma and ion sources are explained. The latter include gridded and gridless sources. Many examples are given, including sources based on DC, RF, and microwave discharges, some with special geometries like hollow cathodes and E x B configurations.

  5. Charge-carrier transport in large-area epitaxial graphene

    Energy Technology Data Exchange (ETDEWEB)

    Kisslinger, Ferdinand; Popp, Matthias; Weber, Heiko B. [Lehrstuhl fuer Angewandte Physik, Friedrich-Alexander-Universitaet Erlangen-Nuernberg (FAU), Erlangen (Germany); Jobst, Johannes [Huygens-Kamerlingh Onnes Laboratorium, Leiden Institute of Physics, Leiden University (Netherlands); Shallcross, Sam [Lehrstuhl fuer theoretische Festkoerperphysik, Friedrich-Alexander-Universitaet Erlangen-Nuernberg (FAU), Erlangen (Germany)

    2017-11-15

    We present an overview of recent charge carrier transport experiments in both monolayer and bilayer graphene, with emphasis on the phenomena that appear in large-area samples. While many aspects of transport are based on quantum mechanical concepts, in the large-area limit classical corrections dominate and shape the magnetoresistance and the tunneling conductance. The discussed phenomena are very general and can, with little modification, be expected in any atomically thin 2D conductor. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Manufacture of axially insulated large-area diodes

    International Nuclear Information System (INIS)

    Ma Weiyi; Zhou Kungang; Wang Youtian; Zhang Dong; Shan Yusheng; Wang Naiyan

    1999-01-01

    The author describes the design and construction of the axially insulated large-area diodes used in the 'Heaven-1'. The four axially insulated large-area diodes are connected to the 10 ohm pulse transmission lines via the vacuum feed through tubes. The experimental results with the diodes are given. The diodes can steadily work at the voltage of 650 kV, and the diode current density is about 80 A per cm 2 with a pulse width of 220 ns. The electron beams with a total energy of 25 kJ are obtained

  7. Large-area metallic photonic lattices for military applications.

    Energy Technology Data Exchange (ETDEWEB)

    Luk, Ting Shan

    2007-11-01

    In this project we developed photonic crystal modeling capability and fabrication technology that is scaleable to large area. An intelligent optimization code was developed to find the optimal structure for the desired spectral response. In terms of fabrication, an exhaustive survey of fabrication techniques that would meet the large area requirement was reduced to Deep X-ray Lithography (DXRL) and nano-imprint. Using DXRL, we fabricated a gold logpile photonic crystal in the <100> plane. For the nano-imprint technique, we fabricated a cubic array of gold squares. These two examples also represent two classes of metallic photonic crystal topologies, the connected network and cermet arrangement.

  8. Material balance areas and frequencies for large reprocessing plants

    International Nuclear Information System (INIS)

    Burr, T.

    1994-01-01

    It has long been recognized that facilities with a large nuclear material throughput will probably not meet the International Atomic Energy Agency (IAEA) goal for detecting trickle diversion of plutonium over periods of about one year. The reason is that measurement errors for plutonium concentration and for liquid volume are often approximately relative over a fairly wide range of true values. Therefore, large throughput facilities will tend to have large uncertainties assigned to their annual throughput. By the same argument, if frequent balances are performed over small material balance areas, then the uncertainty associated with each balance period for each balance area will be small. However, trickle diversion would still be difficult to detect statistically. Because the IAEA will soon be faced with safeguarding a new large-scale reprocessing plant in Japan, it is timely to reconsider the advantages and disadvantages of performing frequent material balances over small balance areas (individual tanks where feasible). Therefore, in this paper the authors present some simulation results to study the effect of balance frequency on loss detection probability, and further simulation results to study possibilities introduced by choosing small balance areas. They conclude by recommending frequent balances over small areas

  9. Large area high-speed metrology SPM system

    International Nuclear Information System (INIS)

    Klapetek, P; Valtr, M; Martinek, J; Picco, L; Payton, O D; Miles, M; Yacoot, A

    2015-01-01

    We present a large area high-speed measuring system capable of rapidly generating nanometre resolution scanning probe microscopy data over mm 2 regions. The system combines a slow moving but accurate large area XYZ scanner with a very fast but less accurate small area XY scanner. This arrangement enables very large areas to be scanned by stitching together the small, rapidly acquired, images from the fast XY scanner while simultaneously moving the slow XYZ scanner across the region of interest. In order to successfully merge the image sequences together two software approaches for calibrating the data from the fast scanner are described. The first utilizes the low uncertainty interferometric sensors of the XYZ scanner while the second implements a genetic algorithm with multiple parameter fitting during the data merging step of the image stitching process. The basic uncertainty components related to these high-speed measurements are also discussed. Both techniques are shown to successfully enable high-resolution, large area images to be generated at least an order of magnitude faster than with a conventional atomic force microscope. (paper)

  10. Large area high-speed metrology SPM system

    Science.gov (United States)

    Klapetek, P.; Valtr, M.; Picco, L.; Payton, O. D.; Martinek, J.; Yacoot, A.; Miles, M.

    2015-02-01

    We present a large area high-speed measuring system capable of rapidly generating nanometre resolution scanning probe microscopy data over mm2 regions. The system combines a slow moving but accurate large area XYZ scanner with a very fast but less accurate small area XY scanner. This arrangement enables very large areas to be scanned by stitching together the small, rapidly acquired, images from the fast XY scanner while simultaneously moving the slow XYZ scanner across the region of interest. In order to successfully merge the image sequences together two software approaches for calibrating the data from the fast scanner are described. The first utilizes the low uncertainty interferometric sensors of the XYZ scanner while the second implements a genetic algorithm with multiple parameter fitting during the data merging step of the image stitching process. The basic uncertainty components related to these high-speed measurements are also discussed. Both techniques are shown to successfully enable high-resolution, large area images to be generated at least an order of magnitude faster than with a conventional atomic force microscope.

  11. Technique investigation on large area neutron scintillation detector array

    International Nuclear Information System (INIS)

    Chen Jiabin

    2006-12-01

    The detailed project for developing Large Area Neutron Scintillation Detector Array (LaNSA) to be used for measuring fusion fuel area density on Shenguang III prototype is presented, including experimental principle, detector working principle, electronics system design and the needs for target chamber etc. The detailed parameters for parts are given and the main causes affecting the system function are analyzed. The realization path is introduced. (authors)

  12. Semiconductor-based, large-area, flexible, electronic devices

    Science.gov (United States)

    Goyal, Amit [Knoxville, TN

    2011-03-15

    Novel articles and methods to fabricate the same resulting in flexible, large-area, triaxially textured, single-crystal or single-crystal-like, semiconductor-based, electronic devices are disclosed. Potential applications of resulting articles are in areas of photovoltaic devices, flat-panel displays, thermophotovoltaic devices, ferroelectric devices, light emitting diode devices, computer hard disc drive devices, magnetoresistance based devices, photoluminescence based devices, non-volatile memory devices, dielectric devices, thermoelectric devices and quantum dot laser devices.

  13. Identifying Corridors among Large Protected Areas in the United States.

    Directory of Open Access Journals (Sweden)

    R Travis Belote

    Full Text Available Conservation scientists emphasize the importance of maintaining a connected network of protected areas to prevent ecosystems and populations from becoming isolated, reduce the risk of extinction, and ultimately sustain biodiversity. Keeping protected areas connected in a network is increasingly recognized as a conservation priority in the current era of rapid climate change. Models that identify suitable linkages between core areas have been used to prioritize potentially important corridors for maintaining functional connectivity. Here, we identify the most "natural" (i.e., least human-modified corridors between large protected areas in the contiguous Unites States. We aggregated results from multiple connectivity models to develop a composite map of corridors reflecting agreement of models run under different assumptions about how human modification of land may influence connectivity. To identify which land units are most important for sustaining structural connectivity, we used the composite map of corridors to evaluate connectivity priorities in two ways: (1 among land units outside of our pool of large core protected areas and (2 among units administratively protected as Inventoried Roadless (IRAs or Wilderness Study Areas (WSAs. Corridor values varied substantially among classes of "unprotected" non-core land units, and land units of high connectivity value and priority represent diverse ownerships and existing levels of protections. We provide a ranking of IRAs and WSAs that should be prioritized for additional protection to maintain minimal human modification. Our results provide a coarse-scale assessment of connectivity priorities for maintaining a connected network of protected areas.

  14. Large area imaging of forensic evidence with MA-XRF

    NARCIS (Netherlands)

    Langstraat, K.; Knijnenberg, A.; Edelman, G.; van de Merwe, L.; van Loon, A.; Dik, J.; van Asten, A.

    2017-01-01

    This study introduces the use of macroscopic X-ray fluorescence (MA-XRF) for the detection, classification and imaging of forensic traces over large object areas such as entire pieces of clothing and wall paneling. MA-XRF was sufficiently sensitive and selective to detect human biological traces

  15. Large area imaging of forensic evidence with MA-XRF

    NARCIS (Netherlands)

    Langstraat, Kirsten; Knijnenberg, Alwin; Edelman, Gerda; Van De Merwe, Linda; van Loon, A.; Dik, J.; van Asten, Arian C.

    2017-01-01

    This study introduces the use of macroscopic X-ray fluorescence (MA-XRF) for the detection, classification and imaging of forensic traces over large object areas such as entire pieces of clothing and wall paneling. MA-XRF was sufficiently sensitive and selective to detect human biological traces

  16. Large area, low cost solar cell development and production readiness

    Science.gov (United States)

    Michaels, D.

    1982-01-01

    A process sequence for a large area ( or = 25 sq. cm) silicon solar cell was investigated. Generic cell choice was guided by the expected electron fluence, by the packing factors of various cell envelope designs onto each panel to provide needed voltage as well as current, by the weight constraints on the system, and by the cost goals of the contract.

  17. Beam test of a large area silicon drift detector

    International Nuclear Information System (INIS)

    Castoldi, A.; Chinnici, S.; Gatti, E.; Longoni, A.; Palma, F.; Sampietro, M.; Rehak, P.; Ballocchi, G.; Kemmer, J.; Holl, P.; Cox, P.T.; Giacomelli, P.; Vacchi, A.

    1992-01-01

    The results from the tests of the first large area (4 x 4 cm 2 ) planar silicon drift detector prototype in a pion beam are reported. The measured position resolution in the drift direction is (σ=40 ± 10)μm

  18. Fabrication of large area flexible nanoplasmonic templates with flow coating

    Science.gov (United States)

    Huang, Qian; Devetter, Brent M.; Roosendaal, Timothy; LaBerge, Max; Bernacki, Bruce E.; Alvine, Kyle J.

    2017-07-01

    We describe the development of a custom-built two-axis flow coater for the deposition of polymeric nanosphere monolayers that could be used in the fabrication of large area nanoplasmonic films. The technique described here has the capability of depositing large areas (up to 7 in. × 10 in.) of self-assembled monolayers of polymeric nanospheres onto polyethylene terephthalate (PET) films. Here, three sets of films consisting of different diameters (ranging from 100 to 300 nm) of polymeric nanospheres were used to demonstrate the capabilities of this instrument. To improve the surface wettability of the PET substrates during wet-deposition, we enhanced the wettability by using a forced air blown-arc plasma treatment system. Both the local microstructure, as confirmed by scanning electron microscopy, describing monolayer and multilayer coverage, and the overall macroscopic uniformity of the resultant nanostructured film were optimized by controlling the relative stage to blade speed and nanosphere concentration. We also show using a smaller nanoparticle template that such monolayers can be used to form nanoplasmonic films. As this flow-coating approach is a scalable technique, large area films such as the ones described here have a variety of crucial emerging applications in areas such as energy, catalysis, and chemical sensing.

  19. Experimental study on generation of large area uniform electron beam

    International Nuclear Information System (INIS)

    Tang Ying; Yi Aiping; Liu Jingru; Qian Hang; Huang Xin; Yu Li; Su Jiancang; Ding Zhenjie; Ding Yongzhong; Yu Jianguo

    2007-01-01

    In the experiment of gas laser pumped by electron beam, large area uniform electron beam is important to generate high efficiency laser output. The experimental study on generation of large area uniform electron beam with SPG-200 pulsed power generator is introduced. SPG-200 is an all-solid-state components pulsed power generator based on SOS, and its open voltage is more than 350 kV. The cathode have the area of 24 mm x 294 mm, and the anode-cathode(A-C)gap spacing is adjustable from 0 to 49 mm. The electron beam of cathode emission is transported to the laser chamber through the diode pressure foil, which sepa-rates the vacuum chamber from the laser chamber. Velvet and graphite cathodes are studied, each generates large area electron beam. The diode parameters are presented, and the uniformity of e-beam is diagnosed. The experimental results show that the diode voltage of the graphite cathode is 240-280 kV, and the diode current is 0.7-1.8 kA. The diode voltage of the velvet cathode is 200-250 kV, and the diode current is 1.5-1.7 kA. The uniformity of the velvet cathode emission is better than that of the graphite cathode. (authors)

  20. Regulations and Strategy for a Loss of Large Area

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Heok-soon [KHNP CRI, Daejeon (Korea, Republic of)

    2016-10-15

    The Nuclear Regulatory Commission (NRC) has issued 10 CFR 50.54(hh) that requires licensees to develop guidance and strategies for addressing the loss of large areas of the plant due to explosions or fires from a beyond-design basis event through the use of readily available resources and by identifying potential practicable areas for the use of beyond-readily-available resources. These strategies would address licensee response to events that are beyond the design basis of the facility. This paper illustrates overview of Regulations and some important Strategy for a Loss of Large Area of an advanced nuclear power plant. Regulations and Strategy for Loss of Large Area Analysis could be overlooked during the development stage of Physical Protection System. KHNP was done the project of Physical Protection System design including LOLA to meet the criteria of U.S. NRC and IAEA requirements in INFCIRC/225/Rev.5. The New Reactor should meet the regulatory requirements for LOLA. In the future, the results of project will expect to apply new NPPs.

  1. Spatially explicit shallow landslide susceptibility mapping over large areas

    Science.gov (United States)

    Bellugi, Dino; Dietrich, William E.; Stock, Jonathan D.; McKean, Jim; Kazian, Brian; Hargrove, Paul

    2011-01-01

    Recent advances in downscaling climate model precipitation predictions now yield spatially explicit patterns of rainfall that could be used to estimate shallow landslide susceptibility over large areas. In California, the United States Geological Survey is exploring community emergency response to the possible effects of a very large simulated storm event and to do so it has generated downscaled precipitation maps for the storm. To predict the corresponding pattern of shallow landslide susceptibility across the state, we have used the model Shalstab (a coupled steady state runoff and infinite slope stability model) which susceptibility spatially explicit estimates of relative potential instability. Such slope stability models that include the effects of subsurface runoff on potentially destabilizing pore pressure evolution require water routing and hence the definition of upslope drainage area to each potential cell. To calculate drainage area efficiently over a large area we developed a parallel framework to scale-up Shalstab and specifically introduce a new efficient parallel drainage area algorithm which produces seamless results. The single seamless shallow landslide susceptibility map for all of California was accomplished in a short run time, and indicates that much larger areas can be efficiently modelled. As landslide maps generally over predict the extent of instability for any given storm. Local empirical data on the fraction of predicted unstable cells that failed for observed rainfall intensity can be used to specify the likely extent of hazard for a given storm. This suggests that campaigns to collect local precipitation data and detailed shallow landslide location maps after major storms could be used to calibrate models and improve their use in hazard assessment for individual storms.

  2. Rabi-like splitting from large area plasmonic microcavity

    Directory of Open Access Journals (Sweden)

    Fatemeh Hosseini Alast

    2017-08-01

    Full Text Available Rabi-like splitting was observed from a hybrid plasmonic microcavity. The splitting comes from the coupling of cavity mode with the surface plasmon polariton mode; anti-crossing was observed alongside the modal conversional channel on the reflection light measurement. The hybrid device consists of a 10x10 mm2 ruled metal grating integrated onto the Fabry-Perot microcavity. The 10x10 mm2 ruled metal grating fabricated from laser interference and the area is sufficiently large to be used in the practical optical device. The larger area hybrid plasmonic microcavity can be employed in polariton lasers and biosensors.

  3. Large-area, laterally-grown epitaxial semiconductor layers

    Science.gov (United States)

    Han, Jung; Song, Jie; Chen, Danti

    2017-07-18

    Structures and methods for confined lateral-guided growth of a large-area semiconductor layer on an insulating layer are described. The semiconductor layer may be formed by heteroepitaxial growth from a selective growth area in a vertically-confined, lateral-growth guiding structure. Lateral-growth guiding structures may be formed in arrays over a region of a substrate, so as to cover a majority of the substrate region with laterally-grown epitaxial semiconductor tiles. Quality regions of low-defect, stress-free GaN may be grown on silicon.

  4. Uniformity studies in large area triple-GEM based detectors

    Energy Technology Data Exchange (ETDEWEB)

    Akl, M. Abi [Science Program, Texas A& M University at Qatar, PO Box 23874, Doha (Qatar); Bouhali, O., E-mail: othmane.bouhali@qatar.tamu.edu [Science Program, Texas A& M University at Qatar, PO Box 23874, Doha (Qatar); Qatar Computing Research Institute, Hamad Bin Khalifa University, PO Box 5825, Doha (Qatar); Castaneda, A.; Maghrbi, Y.; Mohamed, T. [Science Program, Texas A& M University at Qatar, PO Box 23874, Doha (Qatar)

    2016-10-01

    Gas Electron Multiplier (GEM) based detectors have been used in many applications since their introduction in 1997. Large areas, e.g. exceeding 30×30 cm{sup 2}, of GEM detectors are foreseen in future experiments which puts stringent requirements on the uniformity of response across the detection area. We investigate the effect of small variations of several parameters that could affect the uniformity. Parameters such as the anode pitch, the gas gap, the size and the shape of the holes are investigated. Simulation results are presented and compared to previous experimental data.

  5. Large area, surface discharge pumped, vacuum ultraviolet light source

    Science.gov (United States)

    Sze, R.C.; Quigley, G.P.

    1996-12-17

    Large area, surface discharge pumped, vacuum ultraviolet (VUV) light source is disclosed. A contamination-free VUV light source having a 225 cm{sup 2} emission area in the 240-340 nm region of the electromagnetic spectrum with an average output power in this band of about 2 J/cm{sup 2} at a wall-plug efficiency of approximately 5% is described. Only ceramics and metal parts are employed in this surface discharge source. Because of the contamination-free, high photon energy and flux, and short pulse characteristics of the source, it is suitable for semiconductor and flat panel display material processing. 3 figs.

  6. Large-area smart glass and integrated photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Lampert, C.M. [Star Science, 8730 Water Road, Cotati, CA 94931-4252 (United States)

    2003-04-01

    Several companies throughout the world are developing dynamic glazing and large-area flat panel displays. University and National Laboratory groups are researching new materials and processes to improve these products. The concept of a switchable glazing for building and vehicle application is very attractive. Conventional glazing only offers fixed transmittance and control of energy passing through it. Given the wide range of illumination conditions and glare, a dynamic glazing with adjustable transmittance offers the best solution. Photovoltaics can be integrated as power sources for smart windows. In this way a switchable window could be a completely stand alone smart system. A new range of large-area flat panel display including light-weight and flexible displays are being developed. These displays can be used for banner advertising, dynamic pricing in stores, electronic paper, and electronic books, to name only a few applications. This study covers selected switching technologies including electrochromism, suspended particles, and encapsulated liquid crystals.

  7. Dwell time considerations for large area cold plasma decontamination

    Science.gov (United States)

    Konesky, Gregory

    2009-05-01

    Atmospheric discharge cold plasmas have been shown to be effective in the reduction of pathogenic bacteria and spores and in the decontamination of simulated chemical warfare agents, without the generation of toxic or harmful by-products. Cold plasmas may also be useful in assisting cleanup of radiological "dirty bombs." For practical applications in realistic scenarios, the plasma applicator must have both a large area of coverage, and a reasonably short dwell time. However, the literature contains a wide range of reported dwell times, from a few seconds to several minutes, needed to achieve a given level of reduction. This is largely due to different experimental conditions, and especially, different methods of generating the decontaminating plasma. We consider these different approaches and attempt to draw equivalencies among them, and use this to develop requirements for a practical, field-deployable plasma decontamination system. A plasma applicator with 12 square inches area and integral high voltage, high frequency generator is described.

  8. An insulating grid spacer for large-area MICROMEGAS chambers

    International Nuclear Information System (INIS)

    Bernard, D.; Delagrange, H.; D'Enterria, D.G.; Guay, M.L.M. Le; Martinez, G.; Mora, M.J.; Pichot, P.; Roy, D.; Schutz, Y.; Gandi, A.; Oliveira, R. de

    2002-01-01

    We present a novel design for large-area gaseous detectors based on the MICROMEGAS technology. This technology incorporates an insulating grid, sandwiched between the micro-mesh and the anode-pad plane, which provides a uniform 200 μm amplification gap. The uniformity of the amplification gap thickness has been verified. The gain performances of the detector are presented and compared to the values obtained with detectors using cylindrical micro spacers. The new design presents several technical and financial advantages

  9. Large area avalanche MRS-photodiodes for nuclear spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ermalitski, F A; Zalesski, V B

    1996-12-31

    Problems of application of avalanche photodiodes (APD) in readout systems of nuclear spectrometers are considered. APD`s with a large sensitive area of a diameter 1-5 mm and a high multiplication coefficient 200-1000 are created. MPS-photodiodes provide for the energy resolution 80% at temperature 231 K for detecting gamma-quanta with energy 662 keV. 4 refs.

  10. Gravure printing of graphene for large-area flexible electronics.

    Science.gov (United States)

    Secor, Ethan B; Lim, Sooman; Zhang, Heng; Frisbie, C Daniel; Francis, Lorraine F; Hersam, Mark C

    2014-07-09

    Gravure printing of graphene is demonstrated for the rapid production of conductive patterns on flexible substrates. Development of suitable inks and printing parameters enables the fabrication of patterns with a resolution down to 30 μm. A mild annealing step yields conductive lines with high reliability and uniformity, providing an efficient method for the integration of graphene into large-area printed and flexible electronics. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Mapping the electrical properties of large-area graphene

    Science.gov (United States)

    Bøggild, Peter; Mackenzie, David M. A.; Whelan, Patrick R.; Petersen, Dirch H.; Due Buron, Jonas; Zurutuza, Amaia; Gallop, John; Hao, Ling; Jepsen, Peter U.

    2017-12-01

    The significant progress in terms of fabricating large-area graphene films for transparent electrodes, barriers, electronics, telecommunication and other applications has not yet been accompanied by efficient methods for characterizing the electrical properties of large-area graphene. While in the early prototyping as well as research and development phases, electrical test devices created by conventional lithography have provided adequate insights, this approach is becoming increasingly problematic due to complications such as irreversible damage to the original graphene film, contamination, and a high measurement effort per device. In this topical review, we provide a comprehensive overview of the issues that need to be addressed by any large-area characterisation method for electrical key performance indicators, with emphasis on electrical uniformity and on how this can be used to provide a more accurate analysis of the graphene film. We review and compare three different, but complementary approaches that rely either on fixed contacts (dry laser lithography), movable contacts (micro four point probes) and non-contact (terahertz time-domain spectroscopy) between the probe and the graphene film, all of which have been optimized for maximal throughput and accuracy, and minimal damage to the graphene film. Of these three, the main emphasis is on THz time-domain spectroscopy, which is non-destructive, highly accurate and allows both conductivity, carrier density and carrier mobility to be mapped across arbitrarily large areas at rates that by far exceed any other known method. We also detail how the THz conductivity spectra give insights on the scattering mechanisms, and through that, the microstructure of graphene films subject to different growth and transfer processes. The perspectives for upscaling to realistic production environments are discussed.

  12. High Energy Astrophysics with the Fermi Large Area Telescope

    Science.gov (United States)

    Hays, Elizabeth

    2009-01-01

    This slide presentation reviews some of the findings of the Large Area Telescope (LAT) aboard the Fermi Observatory. It includes information about the LAT, and the Gamma-Ray Burst Monitor (GBM), detection of the quiet sun and the moon in gamma rays, Pulsars observed by the observatory, Globular Star Clusters, Active Galactic Nucleus, and Gamma-Ray Bursts, with specific information about GRB 080916C.

  13. Advanced Large Area Plastic Scintillator Project (ALPS): Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, David V.; Reeder, Paul L.; Todd, Lindsay C.; Warren, Glen A.; McCormick, Kathleen R.; Stephens, Daniel L.; Geelhood, Bruce D.; Alzheimer, James M.; Crowell, Shannon L.; Sliger, William A.

    2008-02-05

    The advanced Large-Area Plastic Scintillator (ALPS) Project at Pacific Northwest National Laboratory investigated possible technological avenues for substantially advancing the state-of-the-art in gamma-ray detection via large-area plastic scintillators. The three predominant themes of these investigations comprised the following: * Maximizing light collection efficiency from a single large-area sheet of plastic scintillator, and optimizing hardware event trigger definition to retain detection efficiency while exploiting the power of coincidence to suppress single-PMT "dark current" background; * Utilizing anti-Compton vetoing and supplementary spectral information from a co-located secondary, or "Back" detector, to both (1) minimize Compton background in the low-energy portion of the "Front" scintillator's pulse-height spectrum, and (2) sharpen the statistical accuracy of the front detector's low-energy response prediction as impelmented in suitable energy-windowing algorithms; and * Investigating alternative materials to enhance the intrinsic gamma-ray detection efficiency of plastic-based sensors.

  14. Advanced Large Area Plastic Scintillator Project (ALPS): Final Report

    International Nuclear Information System (INIS)

    Jordan, David V.; Reeder, Paul L.; Todd, Lindsay C.; Warren, Glen A.; McCormick, Kathleen R.; Stephens, Daniel L.; Geelhood, Bruce D.; Alzheimer, James M.; Crowell, Shannon L.; Sliger, William A.

    2008-01-01

    The advanced Large-Area Plastic Scintillator (ALPS) Project at Pacific Northwest National Laboratory investigated possible technological avenues for substantially advancing the state-of-the-art in gamma-ray detection via large-area plastic scintillators. The three predominant themes of these investigations comprised the following: * Maximizing light collection efficiency from a single large-area sheet of plastic scintillator, and optimizing hardware event trigger definition to retain detection efficiency while exploiting the power of coincidence to suppress single-PMT 'dark current' background; * Utilizing anti-Compton vetoing and supplementary spectral information from a co-located secondary, or 'Back' detector, to both (1) minimize Compton background in the low-energy portion of the 'Front' scintillator's pulse-height spectrum, and (2) sharpen the statistical accuracy of the front detector's low-energy response prediction as implemented in suitable energy-windowing algorithms; and * Investigating alternative materials to enhance the intrinsic gamma-ray detection efficiency of plastic-based sensors

  15. Characterization and Calibration of Large Area Resistive Strip Micromegas Detectors

    CERN Document Server

    Losel, Philipp Jonathan; The ATLAS collaboration

    2015-01-01

    Resisitve strip Micromegas detectors behave discharge tolerant. They have been tested extensively as smaller detectors of about 10 x 10 cm$^2$ in size and they work reliably at high rates of 100\\,kHz/cm$^2$ and above. Tracking resolutions well below 100\\,$\\mu$m have been observed for 100 GeV muons and pions. Micromegas detectors are meanwhile proposed as large area muon precision trackers of 2-3\\,m$^2$ in size. To investigate possible differences between small and large detectors, a 1\\,m$^2$ detector with 2048 resistive strips at a pitch of 450 $\\mu$m was studied in the LMU Cosmic Ray Facility (CRF) using two 4 $\\times$ 2.2 m$^2$ large Monitored Drift Tube (MDT) chambers for cosmic muon reference tracking. Segmentation of the resistive strip anode plane in 57.6\\,mm x 95\\,mm large areas has been realized by the readout of 128 strips with one APV25 chip each and by 11 95\\,mm broad trigger scintillators placed along the readout strips.\\\\ This allows for mapping of homogenity in pulse height and efficiency, deter...

  16. Characterization and Calibration of Large Area Resistive Strip Micromegas Detectors

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00389527; The ATLAS collaboration

    2016-01-01

    Resistive strip Micromegas detectors are discharge tolerant. They have been tested extensively as small detectors of about 10 x 10 cm$^2$ in size and they work reliably at high rates of 100 kHz/cm$^2$ and above. Tracking resolution well below 100 $\\mu$m has been observed for 100 GeV muons and pions. Micromegas detectors are meanwhile proposed as large area muon precision trackers of 2-3 m$^2$ in size. To investigate possible differences between small and large detectors, a 1 m$^2$ detector with 2048 resistive strips at a pitch of 450 $\\mu$m was studied in the LMU Cosmic Ray Measurement Facility (CRMF) using two 4 $\\times$ 2.2 m$^2$ large Monitored Drift Tube (MDT) chambers for cosmic muon reference tracking. A segmentation of the resistive strip anode plane in 57.6 mm x 93 mm large areas has been realized by the readout of 128 strips with one APV25 chip each and by eleven 93 mm broad trigger scintillators placed along the readout strips. This allows for mapping of homogeneity in pulse height and efficiency, d...

  17. Large-area high-efficiency flexible PHOLED lighting panels

    Science.gov (United States)

    Pang, Huiqing; Mandlik, Prashant; Levermore, Peter A.; Silvernail, Jeff; Ma, Ruiqing; Brown, Julie J.

    2012-09-01

    Organic Light Emitting Diodes (OLEDs) provide various attractive features for next generation illumination systems, including high efficiency, low power, thin and flexible form factor. In this work, we incorporated phosphorescent emitters and demonstrated highly efficient white phosphorescent OLED (PHOLED) devices on flexible plastic substrates. The 0.94 cm2 small-area device has total thickness of approximately 0.25 mm and achieved 63 lm/W at 1,000 cd/m2 with CRI = 85 and CCT = 2920 K. We further designed and fabricated a 15 cm x 15 cm large-area flexible white OLED lighting panels, finished with a hybrid single-layer ultra-low permeability single layer barrier (SLB) encapsulation film. The flexible panel has an active area of 116.4 cm2, and achieved a power efficacy of 47 lm/W at 1,000 cd/m2 with CRI = 83 and CCT = 3470 K. The efficacy of the panel at 3,000 cd/m2 is 43 lm/W. The large-area flexible PHOLED lighting panel is to bring out enormous possibilities to the future general lighting applications.

  18. Large-area photogrammetry based testing of wind turbine blades

    Science.gov (United States)

    Poozesh, Peyman; Baqersad, Javad; Niezrecki, Christopher; Avitabile, Peter; Harvey, Eric; Yarala, Rahul

    2017-03-01

    An optically based sensing system that can measure the displacement and strain over essentially the entire area of a utility-scale blade leads to a measurement system that can significantly reduce the time and cost associated with traditional instrumentation. This paper evaluates the performance of conventional three dimensional digital image correlation (3D DIC) and three dimensional point tracking (3DPT) approaches over the surface of wind turbine blades and proposes a multi-camera measurement system using dynamic spatial data stitching. The potential advantages for the proposed approach include: (1) full-field measurement distributed over a very large area, (2) the elimination of time-consuming wiring and expensive sensors, and (3) the need for large-channel data acquisition systems. There are several challenges associated with extending the capability of a standard 3D DIC system to measure entire surface of utility scale blades to extract distributed strain, deflection, and modal parameters. This paper only tries to address some of the difficulties including: (1) assessing the accuracy of the 3D DIC system to measure full-field distributed strain and displacement over the large area, (2) understanding the geometrical constraints associated with a wind turbine testing facility (e.g. lighting, working distance, and speckle pattern size), (3) evaluating the performance of the dynamic stitching method to combine two different fields of view by extracting modal parameters from aligned point clouds, and (4) determining the feasibility of employing an output-only system identification to estimate modal parameters of a utility scale wind turbine blade from optically measured data. Within the current work, the results of an optical measurement (one stereo-vision system) performed on a large area over a 50-m utility-scale blade subjected to quasi-static and cyclic loading are presented. The blade certification and testing is typically performed using International

  19. Contribution to the energy calibration of GLAST-LAT's calorimeter and validation of hadronic cascade models available with GEANT4

    International Nuclear Information System (INIS)

    Bregeon, J.

    2005-09-01

    GLAST is the new generation of Gamma-ray telescope and should dramatically improve our knowledge of the gamma-ray sky when it is launched on September 7. 2007. Data from the beam test that was held at GANIL with low energy ions were analyzed in order to measure the light quenching factor of CsI for all kinds of ions from proton to krypton of energy between 0 and 73 MeV per nucleon. These results have been very useful to understand the light quenching for relativistic ions that was measured during the GSI beam test. The knowledge of light quenching in GLAST CsI detectors for high energy ions is required for the on-orbit calibration with cosmic rays to succeed. Hadronic background rejection is another major issue for GLAST, thus, all the algorithms rely on the GLAST official Monte-Carlo simulation, GlastRelease. Hadronic cascade data from the GSI beam test and from another beam test held at CERN on the SPS have been used to benchmark hadronic cascade simulation within the framework of GEANT4, on which GlastRelease is based. Testing the good reproduction of simple parameters in GLAST-like calorimeters for hadronic cascades generated by 1.7 GeV, 3.4 GeV, 10 GeV and 20 GeV protons or pions led us to the conclusion that at high energy the default LHEP model is good enough, whereas at low energy the Bertini intra-nuclear cascade model should be used. (author)

  20. Priority areas for large mammal conservation in Equatorial Guinea.

    Science.gov (United States)

    Murai, Mizuki; Ruffler, Heidi; Berlemont, Antoine; Campbell, Genevieve; Esono, Fidel; Agbor, Anthony; Mbomio, Domingo; Ebana, Agustín; Nze, Antonio; Kühl, Hjalmar S

    2013-01-01

    Hunting is one of the main driving forces behind large mammal density distribution in many regions of the world. In tropical Africa, urban demand for bushmeat has been shown to dominate over subsistence hunting and its impact often overrides spatial-ecological species characteristics. To effectively protect remaining mammal populations the main factors that influence their distribution need to be integrated into conservation area prioritisation and management plans. This information has been lacking for Río Muni, Equatorial Guinea, as prior studies have been outdated or have not systematically covered the continental region of the country. In this study we evaluated: 1) the relative importance of local vs. commercial hunting; 2) wildlife density of protected vs. non-protected areas; and 3) the importance of ecological factors vs. human influence in driving mammal density distribution in Río Muni. We adopted a systematic countrywide line transect approach with particular focus on apes and elephants, but also including other mammal species. For analysis of field data we used generalised linear models with a set of predictor variables representing ecological conditions, anthropogenic pressure and protected areas. We estimate that there are currently 884 (437-1,789) elephants and 11,097 (8,719-13,592) chimpanzees and gorillas remaining in Río Muni. The results indicate strong hunting pressures on both local and commercial levels, with roads demonstrating a negative impact on elephants and overall mammal body mass. Protected areas played no role in determining any of the mammal species distributions and significant human hunting signs were found inside these protected areas, illustrating the lack of environmental law enforcement throughout the country. Río Muni is currently under-represented in conservation efforts in Western Equatorial Africa, and we recommend a focus on cross-boundary conservation, in particular in the Monte Alén-Monts de Cristal and Río Campo

  1. Application issues for large-area electrochromic windows incommercial buildings

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Eleanor S.; DiBartolomeo, D.L.

    2000-05-01

    Projections of performance from small-area devices to large-area windows and enterprise marketing have created high expectations for electrochromic glazings. As a result, this paper seeks to precipitate an objective dialog between material scientists and building-application scientists to determine whether actual large-area electrochromic devices will result in significant performance benefits and what material improvements are needed, if any, to make electrochromics more practical for commercial building applications. Few in-situ tests have been conducted with large-area electrochromic windows applied in buildings. This study presents monitored results from a full-scale field test of large-area electrochromic windows to illustrate how this technology will perform in commercial buildings. The visible transmittance (Tv) of the installed electrochromic ranged from 0.11 to 0.38. The data are limited to the winter period for a south-east-facing window. The effect of actual device performance on lighting energy use, direct sun control, discomfort glare, and interior illumination is discussed. No mechanical system loads were monitored. These data demonstrate the use of electrochromics in a moderate climate and focus on the most restrictive visual task: computer use in offices. Through this small demonstration, we were able to determine that electrochromic windows can indeed provide unmitigated transparent views and a level of dynamic illumination control never before seen in architectural glazing materials. Daily lighting energy use was 6-24 percent less compared to the 11 percent-glazing, with improved interior brightness levels. Daily lighting energy use was 3 percent less to 13 percent more compared to the 38 percent-glazing, with improved window brightness control. The electrochromic window may not be able to fulfill both energy-efficiency and visual comfort objectives when low winter direct sun is present, particularly for computer tasks using cathode-ray tube (CRT

  2. Large area optical mapping of surface contact angle.

    Science.gov (United States)

    Dutra, Guilherme; Canning, John; Padden, Whayne; Martelli, Cicero; Dligatch, Svetlana

    2017-09-04

    Top-down contact angle measurements have been validated and confirmed to be as good if not more reliable than side-based measurements. A range of samples, including industrially relevant materials for roofing and printing, has been compared. Using the top-down approach, mapping in both 1-D and 2-D has been demonstrated. The method was applied to study the change in contact angle as a function of change in silver (Ag) nanoparticle size controlled by thermal evaporation. Large area mapping reveals good uniformity for commercial Aspen paper coated with black laser printer ink. A demonstration of the forensic and chemical analysis potential in 2-D is shown by uncovering the hidden CsF initials made with mineral oil on the coated Aspen paper. The method promises to revolutionize nanoscale characterization and industrial monitoring as well as chemical analyses by allowing rapid contact angle measurements over large areas or large numbers of samples in ways and times that have not been possible before.

  3. Dark Matter Searches with the Fermi Large Area Telescope

    International Nuclear Information System (INIS)

    Meurer, Christine

    2008-01-01

    The Fermi Gamma-Ray Space Telescope, successfully launched on June 11th, 2008, is the next generation satellite experiment for high-energy gamma-ray astronomy. The main instrument, the Fermi Large Area Telescope (LAT), with a wide field of view (>2 sr), a large effective area (>8000 cm 2 at 1 GeV), sub-arcminute source localization, a large energy range (20 MeV-300 GeV) and a good energy resolution (close to 8% at 1 GeV), has excellent potential to either discover or to constrain a Dark Matter signal. The Fermi LAT team pursues complementary searches for signatures of particle Dark Matter in different search regions such as the galactic center, galactic satellites and subhalos, the milky way halo, extragalactic regions as well as the search for spectral lines. In these proceedings we examine the potential of the LAT to detect gamma-rays coming from Weakly Interacting Massive Particle annihilations in these regions with special focus on the galactic center region.

  4. Amplifiers dedicated for large area SiC photodiodes

    Science.gov (United States)

    Doroz, P.; Duk, M.; Korwin-Pawlowski, M. L.; Borecki, M.

    2016-09-01

    Large area SiC photodiodes find applications in optoelectronic sensors working at special conditions. These conditions include detection of UV radiation in harsh environment. Moreover, the mentioned sensors have to be selective and resistant to unwanted signals. For this purpose, the modulation of light at source unit and the rejection of constant current and low frequency component of signal at detector unit are used. The popular frequency used for modulation in such sensor is 1kHz. The large area photodiodes are characterized by a large capacitance and low shunt resistance that varies with polarization of the photodiode and can significantly modify the conditions of signal pre-amplification. In this paper two pre-amplifiers topology are analyzed: the transimpedance amplifier and the non-inverting voltage to voltage amplifier with negative feedback. The feedback loops of both pre-amplifiers are equipped with elements used for initial constant current and low frequency signals rejections. Both circuits are analyzed and compared using simulation and experimental approaches.

  5. Multimodality treatment of large AVMs in eloquent areas

    International Nuclear Information System (INIS)

    Inoue, Hiroshi K.; Naitou, Isao

    2004-01-01

    Our treatment of arteriovenous malformations (AVMs) with Gamma Knife Radiosurgery (optimal dose treatment) showed 88.4% total obliteration in small AVMs less than 10 ml after the first treatment and very low morbidity (1.7%) in long-term follow-up (5 to 12 years). These results indicate that combined treatment is a good strategy for large AVMs in eloquent areas. Therefore, we evaluated larger AVMs treated with direct surgery including feeder clipping and/or intravascular embolization prior to radiosurgery for further development of radiosurgery of large AVMs. Fifty of 171 patients had combined treatment (embolization: 27, direct surgery: 19, both: 4) and were followed more than 4 years and 6 months. Mean volume at the time of radiosurgery was smallest in the surgery group. Total obliteration was obtained in 94.4% of small AVMs less than 10 ml (surgery: 100%, embolization: 88.9%), although larger AVMs still have a lower obliteration rate. No lethal hemorrhages appeared after combination treatment up to date. We concluded that radiosurgery combined with surgery and/or embolization is a safe and effective treatment for large AVMs in eloquent areas. (author)

  6. Edge field emission of large-area single layer graphene

    Energy Technology Data Exchange (ETDEWEB)

    Kleshch, Victor I., E-mail: klesch@polly.phys.msu.ru [Department of Physics, M.V. Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Bandurin, Denis A. [Department of Physics, M.V. Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Orekhov, Anton S. [Department of Physics, M.V. Lomonosov Moscow State University, Moscow 119991 (Russian Federation); A.V. Shubnikov Institute of Crystallography, RAS, Moscow 119333 (Russian Federation); Purcell, Stephen T. [ILM, Université Claude Bernard Lyon 1 et CNRS, UMR 5586, 69622 Villeurbanne (France); Obraztsov, Alexander N. [Department of Physics, M.V. Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Department of Physics and Mathematics, University of Eastern Finland, Joensuu 80101 (Finland)

    2015-12-01

    Graphical abstract: - Highlights: • Stable field emission was observed from the edge of large-area graphene on quartz. • A strong hysteresis in current–voltage characteristics was observed. • The hysteresis was explained by mechanical peeling of graphene edge from substrate. • Reversible peeling of graphene edge may be used in microelectromechanical systems. - Abstract: Field electron emission from the edges of large-area (∼1 cm × 1 cm) graphene films deposited onto quartz wafers was studied. The graphene was previously grown by chemical vapour deposition on copper. An extreme enhancement of electrostatic field at the edge of the films with macroscopically large lateral dimensions and with single atom thickness was achieved. This resulted in the creation of a blade type electron emitter, providing stable field emission at low-voltage with linear current density up to 0.5 mA/cm. A strong hysteresis in current–voltage characteristics and a step-like increase of the emission current during voltage ramp up were observed. These effects were explained by the local mechanical peeling of the graphene edge from the quartz substrate by the ponderomotive force during the field emission process. Specific field emission phenomena exhibited in the experimental study are explained by a unique combination of structural, electronic and mechanical properties of graphene. Various potential applications ranging from linear electron beam sources to microelectromechanical systems are discussed.

  7. LLNL large-area inductively coupled plasma (ICP) source: Experiments

    International Nuclear Information System (INIS)

    Richardson, R.A.; Egan, P.O.; Benjamin, R.D.

    1995-05-01

    We describe initial experiments with a large (76-cm diameter) plasma source chamber to explore the problems associated with large-area inductively coupled plasma (ICP) sources to produce high density plasmas useful for processing 400-mm semiconductor wafers. Our experiments typically use a 640-nun diameter planar ICP coil driven at 13.56 MHz. Plasma and system data are taken in Ar and N 2 over the pressure range 3-50 mtorr. RF inductive power was run up to 2000W, but typically data were taken over the range 100-1000W. Diagnostics include optical emission spectroscopy, Langmuir probes, and B probes as well as electrical circuit measurements. The B and E-M measurements are compared with models based on commercial E-M codes. Initial indications are that uniform plasmas suitable for 400-mm processing are attainable

  8. Background simulations for the Large Area Detector onboard LOFT

    DEFF Research Database (Denmark)

    Campana, Riccardo; Feroci, Marco; Ettore, Del Monte

    2013-01-01

    and magnetic fields around compact objects and in supranuclear density conditions. Having an effective area of similar to 10 m(2) at 8 keV, LOFT will be able to measure with high sensitivity very fast variability in the X-ray fluxes and spectra. A good knowledge of the in-orbit background environment...... is essential to assess the scientific performance of the mission and optimize the design of its main instrument, the Large Area Detector (LAD). In this paper the results of an extensive Geant-4 simulation of the instrumentwillbe discussed, showing the main contributions to the background and the design...... an anticipated modulation of the background rate as small as 10 % over the orbital timescale. The intrinsic photonic origin of the largest background component also allows for an efficient modelling, supported by an in-flight active monitoring, allowing to predict systematic residuals significantly better than...

  9. Method of manufacturing a large-area segmented photovoltaic module

    Science.gov (United States)

    Lenox, Carl

    2013-11-05

    One embodiment of the invention relates to a segmented photovoltaic (PV) module which is manufactured from laminate segments. The segmented PV module includes rectangular-shaped laminate segments formed from rectangular-shaped PV laminates and further includes non-rectangular-shaped laminate segments formed from rectangular-shaped and approximately-triangular-shaped PV laminates. The laminate segments are mechanically joined and electrically interconnected to form the segmented module. Another embodiment relates to a method of manufacturing a large-area segmented photovoltaic module from laminate segments of various shapes. Other embodiments relate to processes for providing a photovoltaic array for installation at a site. Other embodiments and features are also disclosed.

  10. An insulating grid spacer for large-area MICROMEGAS chambers

    CERN Document Server

    Bernard, D; D'Enterria, D G; Le Guay, M; Martínez, G; Mora, M J; Pichot, P; Roy, D; Schutz, Y; Gandi, A; De Oliveira, R

    2002-01-01

    We present an original design for large area gaseous detectors based on the MICROMEGAS technology. This technology incorporates an insulating grid, sandwiched between the micro-mesh and the anode-pad plane, which provides an uniform 200 $\\mu$m amplification gap. The uniformity of the amplification gap thickness has been verified under several experimental conditions. The gain performances of the detector are presented and compared to the values obtained with detectors using cylindrical micro spacers. The new design presents several technical and financial advantages.

  11. Development of large area resistive electrodes for ATLAS NSW Micromegas

    Science.gov (United States)

    Ochi, Atsuhiko

    2018-02-01

    Micromegas with resistive anodes will be used for the NSW upgrades of the ATLAS experiment at LHC. Resistive electrodes are used in MPGD devices to prevent sparks in high-rate operation. Large-area resistive electrodes for Micromegas have been developed using two different technologies: screen printing and carbon sputtering. The maximum resistive foil size is 45 × 220 cm with a printed pattern of 425-μm pitch strips. These technologies are also suitable for mass production. Prototypes of a production model series have been successfully produced. In this paper, we report the development, the production status, and the test results of resistive Micromegas.

  12. Position reconstruction in large-area scintillating fibre detectors

    Energy Technology Data Exchange (ETDEWEB)

    Mahata, K. [Gesellschaft fuer Schwerionenforschung (GSI), D-64291 Darmstadt (Germany); Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India)], E-mail: kmahata@barc.gov.in; Johansson, H.T. [Gesellschaft fuer Schwerionenforschung (GSI), D-64291 Darmstadt (Germany); Department of Fundamental Physics, Chalmers University of Technology, S-412 96 Goeteborg (Sweden); Paschalis, S. [Department of Physics, University of Liverpool, Oliver Lodge Laboratory, L69 7ZE (United Kingdom); Simon, H.; Aumann, T. [Gesellschaft fuer Schwerionenforschung (GSI), D-64291 Darmstadt (Germany)

    2009-09-11

    A new analysis procedure has been developed for the large-area scintillating fibre detectors with position-sensitive photomultiplier (PSPM) readout used for heavy ions in the LAND set-up at GSI. It includes gain matching of the PSPM, calibration of the PSPM fibre mask and hit reconstruction. This procedure allows for a quasi-online calibration of this tracking device. It also allows for a precise determination of the position close to the intrinsic detector resolution of 1 mm pitch together with careful treatment of individual event accuracies.

  13. Large area nuclear particle detectors using ET materials

    International Nuclear Information System (INIS)

    1987-08-01

    The purpose of this SBIR Phase 1 feasibility effort was to demonstrate the usefulness of Quantex electron-trapping (ET) materials for spatial detection of nuclear particles over large areas. This demonstration entailed evaluating the prompt visible scintillation as nuclear particles impinged on films of ET materials, and subsequently detecting the nuclear particle impingement information pattern stored in the ET material, by means of the visible-wavelength luminescence produced by near-infrared interrogation. Readily useful levels of scintillation and luminescence outputs are demonstrated

  14. Investigation of electrically exploded large area foil for current switching

    International Nuclear Information System (INIS)

    Chernyshev, V.K.; Boyko, A.M.; Kostyukov, V.N.; Kuzyaev, A.I.; Kulagin, A.A.; Mamyshev, V.I.; Mezhevov, A.B.; Nechaev, A.I.; Petrukhin, A.A.; Protasov, M.S.; Shevtsov, V.I.; Yakubov, V.B.

    1990-01-01

    The possibility of microsecond ∼40 MA current switching from EMG into a quasiconstant inductive load by an electrically exploded foil is investigated. The copper foil of large area, S ∼ 10 4 cm 2 , was placed between thin-walled insulators into a coaxial transmission line (TL). This paper shows a conceptual device scheme. To feed a foil opening switch (FOS), a disc explosive magnetic generator (DEMG) with 20 μs current rise time was employed. An inductive coaxial load was connected to a FOS at a moment, that was close to the foil vaporization start by means of an axisymmetric explosive current commutator (ECC)

  15. Fermi Large Area Telescope Bright Gamma-ray Source List

    Energy Technology Data Exchange (ETDEWEB)

    Abdo, Aous A.; /Naval Research Lab, Wash., D.C.; Ackermann, M.; /KIPAC, Menlo Park /SLAC; Ajello, M.; /KIPAC, Menlo Park /SLAC; Atwood, W.B.; /UC, Santa Cruz; Axelsson, M.; /Stockholm U., OKC /Stockholm U.; Baldini, L.; /INFN, Pisa; Ballet, J.; /DAPNIA, Saclay; Band, D.L.; /NASA, Goddard /NASA, Goddard; Barbiellini, Guido; /INFN, Trieste /Trieste U.; Bastieri, Denis; /INFN, Padua /Padua U.; Bechtol, K.; /KIPAC, Menlo Park /SLAC; Bellazzini, R.; /INFN, Pisa; Berenji, B.; /KIPAC, Menlo Park /SLAC; Bignami, G.F.; /Pavia U.; Bloom, Elliott D.; /KIPAC, Menlo Park /SLAC; Bonamente, E.; /INFN, Perugia /Perugia U.; Borgland, A.W.; /KIPAC, Menlo Park /SLAC; Bregeon, J.; /INFN, Pisa; Brigida, M.; /Bari U. /INFN, Bari; Bruel, P.; /Ecole Polytechnique; Burnett, Thompson H.; /Washington U., Seattle /Bari U. /INFN, Bari /KIPAC, Menlo Park /SLAC /IASF, Milan /IASF, Milan /DAPNIA, Saclay /ASDC, Frascati /INFN, Perugia /Perugia U. /KIPAC, Menlo Park /SLAC /George Mason U. /Naval Research Lab, Wash., D.C. /NASA, Goddard /KIPAC, Menlo Park /SLAC /INFN, Perugia /Perugia U. /KIPAC, Menlo Park /SLAC /Montpellier U. /Sonoma State U. /Stockholm U., OKC /Royal Inst. Tech., Stockholm /Stockholm U. /KIPAC, Menlo Park /SLAC /ASDC, Frascati /NASA, Goddard /Maryland U. /Naval Research Lab, Wash., D.C. /INFN, Trieste /Pavia U. /Bari U. /INFN, Bari /KIPAC, Menlo Park /SLAC /UC, Santa Cruz /KIPAC, Menlo Park /SLAC /KIPAC, Menlo Park /SLAC /KIPAC, Menlo Park /SLAC /Montpellier U. /Bari U. /INFN, Bari /Ecole Polytechnique /NASA, Goddard; /more authors..

    2009-05-15

    Following its launch in 2008 June, the Fermi Gamma-ray Space Telescope (Fermi) began a sky survey in August. The Large Area Telescope (LAT) on Fermi in three months produced a deeper and better resolved map of the {gamma}-ray sky than any previous space mission. We present here initial results for energies above 100 MeV for the 205 most significant (statistical significance greater than {approx}10{sigma}) {gamma}-ray sources in these data. These are the best characterized and best localized point-like (i.e., spatially unresolved) {gamma}-ray sources in the early mission data.

  16. Large area x-ray detectors for cargo radiography

    Science.gov (United States)

    Bueno, C.; Albagli, D.; Bendahan, J.; Castleberry, D.; Gordon, C.; Hopkins, F.; Ross, W.

    2007-04-01

    Large area x-ray detectors based on phosphors coupled to flat panel amorphous silicon diode technology offer significant advances for cargo radiologic imaging. Flat panel area detectors provide large object coverage offering high throughput inspections to meet the high flow rate of container commerce. These detectors provide excellent spatial resolution when needed, and enhanced SNR through low noise electronics. If the resolution is reduced through pixel binning, further advances in SNR are achievable. Extended exposure imaging and frame averaging enables improved x-ray penetration of ultra-thick objects, or "select-your-own" contrast sensitivity at a rate many times faster than LDAs. The areal coverage of flat panel technology provides inherent volumetric imaging with the appropriate scanning methods. Flat panel area detectors have flexible designs in terms of electronic control, scintillator selection, pixel pitch, and frame rates. Their cost is becoming more competitive as production ramps up for the healthcare, nondestructive testing (NDT), and homeland protection industries. Typically used medical and industrial polycrystalline phosphor materials such as Gd2O2S:Tb (GOS) can be applied to megavolt applications if the phosphor layer is sufficiently thick to enhance x-ray absorption, and if a metal radiator is used to augment the quantum detection efficiency and reduce x-ray scatter. Phosphor layers ranging from 0.2-mm to 1-mm can be "sandwiched" between amorphous silicon flat panel diode arrays and metal radiators. Metal plates consisting of W, Pb or Cu, with thicknesses ranging from 0.25-mm to well over 1-mm can be used by covering the entire area of the phosphor plate. In some combinations of high density metal and phosphor layers, the metal plate provides an intensification of 25% in signal due to electron emission from the plate and subsequent excitation within the phosphor material. This further improves the SNR of the system.

  17. Aerial radiation survey techniques for efficient characterization of large areas

    International Nuclear Information System (INIS)

    Sydelko, T.; Riedhauser, S.

    2006-01-01

    Full text: Accidental or intentional releases of radioactive isotopes over potentially very large surface areas can pose serious health risks to humans and ecological receptors. Timely and appropriate responses to these releases depend upon rapid and accurate characterization of impacted areas. These characterization efforts can be adversely impacted by heavy vegetation, rugged terrain, urban environments, and the presence of unknown levels of radioactivity. Aerial survey techniques have proven highly successful in measuring gamma emissions from radiological contaminates of concern quickly, efficiently, and safely. Examples of accidental releases include the unintentional distribution of uranium mining ores during transportation, the loss of uranium processing and waste materials, unintentional nuclear power plant emissions into the atmosphere, and the distribution of isotopes during major flooding events such as the one recently occurring in New Orleans. Intentional releases have occurred during the use of deleted uranium ammunition test firing and war time use by military organizations. The threat of radiological dispersion device (dirty bomb) use by terrorists is currently a major concern of many major cities worldwide. The U.S. Department of Energy, in cooperation with its Remote Sensing Laboratory and Argonne National Laboratory, has developed a sophisticated aerial measurement system for identifying the locations, types, and quantities of gamma emitting radionuclides over extremely large areas. Helicopter mounted Nal detectors are flown at low altitude and constant speed along parallel paths measuring the full spectrum of gamma activity. Analytical procedures are capable of distinguishing between radiological contamination and changes in natural background emissions. Mapped and tabular results of these accurate, timely and cost effective aerial gamma radiation surveys can be used to assist with emergency response actions, if necessary, and to focus more

  18. MILDOS-AREA: An enhanced version of MILDOS for large-area sources

    International Nuclear Information System (INIS)

    Yuan, Y.C.; Wang, J.H.C.; Zielen, A.

    1989-06-01

    The MILDOS-AREA computer code is a modified version of the MILDOS code, which estimates the radiological impacts of airborne emissions from uranium mining and milling facilities or any other large-area source involving emissions of radioisotopes of the uranium-238 series. MILDOS-AREA is designed for execution on personal computers. The modifications incorporated in the MILDOS-AREA code provide enhanced capabilities for calculating doses from large-area sources and update dosimetry calculations. The major revision from the original MILDOS code is the treatment of atmospheric dispersion from area sources: MILDOS-AREA substitutes a finite element integration approach for the virtual-point method (the algorithm used in the original MILDOS code) when specified by the user. Other revisions include the option of using Martin-Tickvart dispersion coefficients in place of Briggs coefficients for a given source, consideration of plume reflection, and updated internal dosimetry calculations based on the most recent recommendations of the International Commission on Radiation Protection and the age-specific dose calculation methodology developed by Oak Ridge National Laboratory. This report also discusses changes in computer code structure incorporated into MILDOS-AREA, summarizes data input requirements, and provides instructions for installing and using the program on personal computers. 15 refs., 9 figs., 26 tabs

  19. Comfort Study of Office Buildings with Large Glazed Areas

    Directory of Open Access Journals (Sweden)

    Violeta Motuzienė

    2017-09-01

    Full Text Available In the buildings with large glazed areas the biggest problem is the space overheating during the warm season. This causes increased energy demand for cooling. The survey was carried out during the warm and cold seasons in two office buildings with large glazed areas. The methodology was prepared for evaluating indoor climate parameters using objective and subjective evaluation. The measurements have shown that there are problems with lighting in workplaces of both buildings during both the warm and cold seasons. The biggest problem is too dry air during the cold period, an acceptable temperature is also not always in the building No. 2. The survey has shown that some employees are dissatisfied with the indoor climate in the workplace, the bigger dissatisfaction is in building No. 2. Assessing according to the O. Fanger methodology was obtained that the number of PPD is in the normal range during the cold period, whereas close to the limit when the building can not be operated in the warm period.

  20. An advanced open path atmospheric pollution monitor for large areas

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, L.; Suhre, D.; Mani, S. [and others

    1996-12-31

    Over 100 million gallons of radioactive and toxic waste materials generated in weapon materials production are stored in 322 tanks buried within large areas at DOE sites. Toxic vapors occur in the tank headspace due to the solvents used and chemical reactions within the tanks. To prevent flammable or explosive concentration of volatile vapors, the headspace are vented, either manually or automatically, to the atmosphere when the headspace pressure exceeds preset values. Furthermore, 67 of the 177 tanks at the DOE Hanford Site are suspected or are known to be leaking into the ground. These underground storage tanks are grouped into tank farms which contain closely spaced tanks in areas as large as 1 km{sup 2}. The objective of this program is to protect DOE personnel and the public by monitoring the air above these tank farms for toxic air pollutants without the monitor entering the tanks farms, which can be radioactive. A secondary objective is to protect personnel by monitoring the air above buried 50 gallon drums containing moderately low radioactive materials but which could also emit toxic air pollutants.

  1. Reactive dual magnetron sputtering for large area application

    International Nuclear Information System (INIS)

    Struempfel, J.

    2002-01-01

    Production lines for large area coating demand high productivity of reactive magnetron sputtering processes. Increased dynamic deposition rates for oxides and nitrides were already obtained by using of highly powered magnetrons in combination with advanced sputter techniques. However, besides high deposition rates the uniformity of such coatings has to be carefully considered. First the basics of reactive sputtering processes and dual magnetron sputtering are summarized. Different methods for process stabilization and control are commonly used for reactive sputtering. The Plasma Emission Monitor (PE M) offers the prerequisite for fast acting process control derived from the in-situ intensity measurements of a spectral line of the sputtered target material. Combined by multiple Plasma Emission Monitor control loops segmented gas manifolds are able to provide excellent thin film uniformity at high deposition rates. The Dual Magnetron allows a broad range of processing by different power supply modes. Medium frequency, DC and pulsed DC power supplies can be used for high quality layers. Whereas the large area coating of highly isolating layers like TiO 2 or SiO 2 is dominated by MF sputtering best results for coating with transparent conductive oxides are obtained by dual DC powering of the dual magnetron arrangement. (Author)

  2. Electrothermal Simulation of Large-Area Semiconductor Devices

    Directory of Open Access Journals (Sweden)

    C Kirsch

    2017-06-01

    Full Text Available The lateral charge transport in thin-film semiconductor devices is affected by the sheet resistance of the various layers. This may lead to a non-uniform current distribution across a large-area device resulting in inhomogeneous luminance, for example, as observed in organic light-emitting diodes (Neyts et al., 2006. The resistive loss in electrical energy is converted into thermal energy via Joule heating, which results in a temperature increase inside the device. On the other hand, the charge transport properties of the device materials are also temperature-dependent, such that we are facing a two-way coupled electrothermal problem. It has been demonstrated that adding thermal effects to an electrical model significantly changes the results (Slawinski et al., 2011. We present a mathematical model for the steady-state distribution of the electric potential and of the temperature across one electrode of a large-area semiconductor device, as well as numerical solutions obtained using the finite element method.

  3. Wind Data Analysis and Wind Flow Simulation Over Large Areas

    Directory of Open Access Journals (Sweden)

    Terziev Angel

    2014-03-01

    Full Text Available Increasing the share of renewable energy sources is one of the core policies of the European Union. This is because of the fact that this energy is essential in reducing the greenhouse gas emissions and securing energy supplies. Currently, the share of wind energy from all renewable energy sources is relatively low. The choice of location for a certain wind farm installation strongly depends on the wind potential. Therefore the accurate assessment of wind potential is extremely important. In the present paper an analysis is made on the impact of significant possible parameters on the determination of wind energy potential for relatively large areas. In the analysis the type of measurements (short- and long-term on-site measurements, the type of instrumentation and the terrain roughness factor are considered. The study on the impact of turbulence on the wind flow distribution over complex terrain is presented, and it is based on the real on-site data collected by the meteorological tall towers installed in the northern part of Bulgaria. By means of CFD based software a wind map is developed for relatively large areas. Different turbulent models in numerical calculations were tested and recommendations for the usage of the specific models in flows modeling over complex terrains are presented. The role of each parameter in wind map development is made. Different approaches for determination of wind energy potential based on the preliminary developed wind map are presented.

  4. Simulations of Large-Area Electron Beam Diodes

    Science.gov (United States)

    Swanekamp, S. B.; Friedman, M.; Ludeking, L.; Smithe, D.; Obenschain, S. P.

    1999-11-01

    Large area electron beam diodes are typically used to pump the amplifiers of KrF lasers. Simulations of large-area electron beam diodes using the particle-in-cell code MAGIC3D have shown the electron flow in the diode to be unstable. Since this instability can potentially produce a non-uniform current and energy distribution in the hibachi structure and lasing medium it can be detrimental to laser efficiency. These results are similar to simulations performed using the ISIS code.(M.E. Jones and V.A. Thomas, Proceedings of the 8^th) International Conference on High-Power Particle Beams, 665 (1990). We have identified the instability as the so called ``transit-time" instability(C.K. Birdsall and W.B. Bridges, Electrodynamics of Diode Regions), (Academic Press, New York, 1966).^,(T.M. Antonsen, W.H. Miner, E. Ott, and A.T. Drobot, Phys. Fluids 27), 1257 (1984). and have investigated the role of the applied magnetic field and diode geometry. Experiments are underway to characterize the instability on the Nike KrF laser system and will be compared to simulation. Also some possible ways to mitigate the instability will be presented.

  5. Large area nanoimprint by substrate conformal imprint lithography (SCIL)

    Science.gov (United States)

    Verschuuren, Marc A.; Megens, Mischa; Ni, Yongfeng; van Sprang, Hans; Polman, Albert

    2017-06-01

    Releasing the potential of advanced material properties by controlled structuring materials on sub-100-nm length scales for applications such as integrated circuits, nano-photonics, (bio-)sensors, lasers, optical security, etc. requires new technology to fabricate nano-patterns on large areas (from cm2 to 200 mm up to display sizes) in a cost-effective manner. Conventional high-end optical lithography such as stepper/scanners is highly capital intensive and not flexible towards substrate types. Nanoimprint has had the potential for over 20 years to bring a cost-effective, flexible method for large area nano-patterning. Over the last 3-4 years, nanoimprint has made great progress towards volume production. The main accelerator has been the switch from rigid- to wafer-scale soft stamps and tool improvements for step and repeat patterning. In this paper, we discuss substrate conformal imprint lithography (SCIL), which combines nanometer resolution, low patterns distortion, and overlay alignment, traditionally reserved for rigid stamps, with the flexibility and robustness of soft stamps. This was made possible by a combination of a new soft stamp material, an inorganic resist, combined with an innovative imprint method. Finally, a volume production solution will be presented, which can pattern up to 60 wafers per hour.

  6. Characterization of new hexagonal large area Geiger Avalanche Photodiodes

    International Nuclear Information System (INIS)

    Boccone, V.; Aguilar, J.A.; Della Volpe, D.; Christov, A.; Montaruli, T.; Rameez, M.; Basili, A.

    2013-06-01

    Photomultipliers (PMTs) are the standard detector for construction of the current generation of imaging Atmospheric Cherenkov Telescopes (IACTs). Despite impressive improvements in QE and reliability in the last years, these devices suffer from the limitation of being unable to operate in the partially illuminated sky (during full or partial moon periods) as the excess light leads to a significant increase in the rate of ageing of the devices themselves and consequently limit the life of the camera. A viable alternative is the large area Geiger-mode avalanche photodiodes (G-APDs also known as Silicon Photomultipliers or SiPMs) that are commercially available from different producers in various types and dimensions. The sufficiency of the maturity of this technology for application to Cherenkov Astronomy has already been demonstrated by the FACT telescope. One of the camera designs under study for the 4 m Davies Cotton Telescope foresees the utilization of a large area G-APDs coupled to non imaging light concentrators. In collaboration with Hamamatsu and deriving from their current technology, we have designed a new hexagonal shaped large area G-APD HEX S12516 which when coupled to a Winston cone of 24 degrees cutting angle allows for a pixel angular resolution of 0.25 degrees for a f/D 1.4 telescope with a diameter of 4 m. The device, available in 2 different cell size configurations (50 μm and 100 μm), is divided into 4 different channels powered in common cathode mode. A temperature sensor was included for a better temperature evaluation in the characterization phase. The first 3 prototypes were fully characterized and the results are compared to the larger area devices commercially available such as the S10985-050C (2x2 array of 3x3 mm 2 G-APDs). The photo-detection efficiency is measured applying the Poisson statistics method using pulsed LED at 7 different wavelengths from 355 to 670 nm and for different bias over-voltages (V ov ). Optical crosstalk and

  7. Large area UV light source with a semiconductor cathode

    International Nuclear Information System (INIS)

    Salamov, B. G.; Ciftci, Y. Oe.; Colakoglu, K.

    2002-01-01

    The light emission (LE) in the UV and visible (blue) range generated by a planar gas discharge system (PGDS) with a semiconductor cathode (SC) are studied. New light source offer high-intensity narrow-band emission at various UV and visible wavelengths (330 - 440 nm). Spectra in N 2 is presented, as well as intensity vs pressure curves for the main peaks of the spectrum. The use of source offers several advantages: PGDS can be extremely efficient energy converters transforming and amplifying a relatively low-powered photon flux incident on the receiving surface of the SC into a flux of high-energy particles over extended areas, i.e. electron, ions, photons. Thus, extremely bright UV and visible sources can be built. LE characteristics of the space in the PGDS are complex, depending on the emitting medium and species. By using the IR light to excite the SC of the system, we have shown that the discharge light emission (DLE) of the device with the N 2 in the gap can serve as an efficient source of the UV radiation if gas pressure and electric field are sufficiently high. This is realized due to the effect of the stabilisation of the spatially homogeneous mode of the discharge in a narrow gap with a large emitting area of SC. Special features of DLE render it highly promising for the development of sources with a large area of the emitting surface, high spatial uniformity of UV radiation, and fast dynamics of these devices. This low cost, high power light sources can provide an interesting alternative to conventional UV lamps

  8. Priority areas for large mammal conservation in Equatorial Guinea.

    Directory of Open Access Journals (Sweden)

    Mizuki Murai

    Full Text Available Hunting is one of the main driving forces behind large mammal density distribution in many regions of the world. In tropical Africa, urban demand for bushmeat has been shown to dominate over subsistence hunting and its impact often overrides spatial-ecological species characteristics. To effectively protect remaining mammal populations the main factors that influence their distribution need to be integrated into conservation area prioritisation and management plans. This information has been lacking for Río Muni, Equatorial Guinea, as prior studies have been outdated or have not systematically covered the continental region of the country. In this study we evaluated: 1 the relative importance of local vs. commercial hunting; 2 wildlife density of protected vs. non-protected areas; and 3 the importance of ecological factors vs. human influence in driving mammal density distribution in Río Muni. We adopted a systematic countrywide line transect approach with particular focus on apes and elephants, but also including other mammal species. For analysis of field data we used generalised linear models with a set of predictor variables representing ecological conditions, anthropogenic pressure and protected areas. We estimate that there are currently 884 (437-1,789 elephants and 11,097 (8,719-13,592 chimpanzees and gorillas remaining in Río Muni. The results indicate strong hunting pressures on both local and commercial levels, with roads demonstrating a negative impact on elephants and overall mammal body mass. Protected areas played no role in determining any of the mammal species distributions and significant human hunting signs were found inside these protected areas, illustrating the lack of environmental law enforcement throughout the country. Río Muni is currently under-represented in conservation efforts in Western Equatorial Africa, and we recommend a focus on cross-boundary conservation, in particular in the Monte Alén-Monts de Cristal

  9. New Gener. High-Energy Spectra of the Blazar 3C 279 with XMM-Newton and GLAST

    Science.gov (United States)

    Collmar, Werner

    2007-10-01

    We propose two 20 ksec XMM-Newton observations of the X-ray bright gamma-ray blazar 3C~279 simultaneous with GLAST/LAT. The main goal is to measure its X-ray properties (spectrum, variability) in order to (1) improve our knowledge on the X-ray emission of the blazar, and (2) to supplement and correlate them to simultaneous GLAST/LAT Gamma-ray observations (30 MeV-300 GeV). Simultaneous GLAST observations of 3C 279 are guaranteed (assuming proper operation then). The high-energy data will be supplemented by ground-based measurements, adding finally up to multifrequency spectra which have unprecedented accuracy and will extend up to high-energy gamma-rays. Such high-quality SEDs will provide severe constraints on their modeling and have the potential to discriminate among models.

  10. Nitrogen large area proportional counter with gas regeneration

    International Nuclear Information System (INIS)

    Leidner, L.; Sadri, E.

    1984-10-01

    A nitrogen large area proportional chamber with gas regeneration is introduced to measure alpha and beta/gamma activites. In contrast to the flow counters used till now the new detector is independent of an external gas supply. The gas amplification factor of nitrogen keeps constant up to an impurity of 2% of O 2 . Oxygen diffusing through unavoidable leakages into the counting gas is removed by an activated catalyzer using low temperature copper oxidation. Humidty is adsorbed by a molecular sieve. The closed counter consists of three components: the actual detector, a gas purification cartridge and a gas circulating pump. Finally, the report describes long run experiments being carried out with prototypes. (orig./HP) [de

  11. Exposure-rate calibration using large-area calibration pads

    International Nuclear Information System (INIS)

    Novak, E.F.

    1988-09-01

    The US Department of Energy (DOE) Office of Remedial Action and Waste Technology established the Technical Measurements Center (TMC) at the DOE Grand Junction Projects Office (GJPO) in Grand Junction, Colorado, to standardize, calibrate, and compare measurements made in support of DOE remedial action programs. A set of large-area, radioelement-enriched concrete pads was constructed by the DOE in 1978 at the Walker Field Airport in Grand Junction for use as calibration standards for airborne gamma-ray spectrometer systems. The use of these pads was investigated by the TMC as potential calibration standards for portable scintillometers employed in measuring gamma-ray exposure rates at Uranium Mill Tailings Remedial Action (UMTRA) project sites. Data acquired on the pads using a pressurized ionization chamber (PIC) and three scintillometers are presented as an illustration of an instrumental calibration. Conclusions and recommended calibration procedures are discussed, based on the results of these data

  12. Digital radiography with large-area flat-panel detectors

    International Nuclear Information System (INIS)

    Kotter, E.; Langer, M.

    2002-01-01

    Large-area flat-panel detectors with active readout mechanisms have been on the market for the past 2 years. This article describes different detector technologies. An important distinction is made between detectors with direct and those with indirect conversion of X-rays into electrical charges. Detectors with indirect conversion are built with unstructured or structured scintillators, the latter resulting in less lateral diffusion of emitted light. Some important qualities of flat-panel detectors are discussed. The first phantom and clinical studies published report an image quality at least comparable to that of screen-film systems and a potential for dose reduction. The available studies are summarised in this article. (orig.)

  13. Coating and Patterning Functional Materials for Large Area Electrofluidic Arrays

    Directory of Open Access Journals (Sweden)

    Hao Wu

    2016-08-01

    Full Text Available Industrialization of electrofluidic devices requires both high performance coating laminates and efficient material utilization on large area substrates. Here we show that screen printing can be effectively used to provide homogeneous pin-hole free patterned amorphous fluoropolymer dielectric layers to provide both the insulating and fluidic reversibility required for devices. Subsequently, we over-coat photoresist using slit coating on this normally extremely hydrophobic layer. In this way, we are able to pattern the photoresist by conventional lithography to provide the chemical contrast required for liquids dosing by self-assembly and highly-reversible electrofluidic switching. Materials, interfacial chemistry, and processing all contribute to the provision of the required engineered substrate properties. Coating homogeneity as characterized by metrology and device performance data are used to validate the methodology, which is well-suited for transfer to high volume production in existing LCD cell-making facilities.

  14. A large area detector for x-ray applications

    International Nuclear Information System (INIS)

    Rodricks, B.; Huang, Qiang; Hopf, R.; Wang, Kemei.

    1993-01-01

    A large area detector for x-ray synchrotron applications has been developed. The front end of this device consist of a scintillator coupled to a fiber-optic taper. The fiber-optic taper is comprised of 4 smaller (70 mm x 70 mm) tapers fused together in a square matrix giving an active area of 140 mm x 140 mm. Each taper has a demagnification of 5.5 resulting in four small ends that are 12 mm diagonally across. The small ends of each taper are coupled to four microchannel-plate-based image intensifiers. The output from each image intensifier is focused onto a Charge Coupled Device (CCD) detector. The four CCDs are read out in parallel and are independently controlled. The image intensifiers also act as fast (20 ns) electronic shutters. The system is capable of displaying images in real time. Additionally, with independent control on the readout of each row of data from the CCD, the system is capable of performing high speed imaging through novel readout manipulation

  15. Optimization of Performance Parameters for Large Area Silicon Photomultipliers

    Science.gov (United States)

    Janzen, Kathryn

    2008-10-01

    The goal of the GlueX experiment is to search for exotic hybrid mesons as evidence of gluonic excitations in an effort to better understand confinement. A key component of the GlueX detector is the electromagnetic barrel calorimeter (BCAL) located immediately inside a superconducting solenoid of approximately 2.5T. Because of this arrangement, traditional vacuum photomultiplier tubes (PMTs) which are affected significantly by magnetic fields cannot be used on the BCAL. The use of Silicon photomultipliers (SiPMs) as front-end detectors has been proposed. While the largest SiPMs that have been previously employed by other experiments are 1x1 mm^2, GlueX proposes to use large area SiPMs each composed of 16 - 3x3 mm^2 cells in a 4x4 array. This puts the GlueX collaboration in the unique position of driving the technology for larger area sensors. In this talk I will discuss tests done in Regina regarding performance parameters of prototype SiPM arrays delivered by SensL, a photonics research and development company based in Ireland, as well as sample 1x1 mm^2 and 3x3 mm^2 SiPMs.

  16. Large area diamond-like carbon coatings by ion implantation

    International Nuclear Information System (INIS)

    McCabe, A.R.; Proctor, G.; Jones, A.M.; Bull, S.J.; Chivers, D.J.

    1993-01-01

    Diamond-like Carbon (DLC) coatings have been deposited onto large geometry components in the Harwell Blue Tank ion implantation facility. To modify the substrate surface and to crack the low vapour pressure oil which is evaporated and condensed onto the surface, a 40 Kev nitrogen ion bucket ion source is used. The coating of areas up to 1 metre in diameter is common and with component manipulation larger areas may be coated. Since the component temperature never exceeds 80 o C during the process, a wide range of materials may be coated including specialist tool steels and even certain high density polymers. In order to produce hard wear resistant coatings with extremely low coefficients of friction (0.02-0.15) and a range of mechanical and electrical properties, various oil precursors have been investigated. The production and assessment of such coatings, including measurements of their tribiological performance, is presented. Applications for wear resistance, corrosion protection and electrically conducting coatings are discussed with examples drawn from engineering, electronics and biomedicine. (7 figures, 13 references). (UK)

  17. Characterising large area silicon drift detectors with MOS injectors

    International Nuclear Information System (INIS)

    Bonvicini, V.; Rashevsky, A.; Vacchi, A.

    1999-01-01

    In the framework of the INFN DSI project, the first prototypes of a large-area Silicon Drift Detector (SDD) have been designed and produced on 5'' diameter wafers of Neutron Transmutation Doped (NTD) silicon with a resistivity of 3000 Ω·cm. The detector is a 'butterfly' bi-directional structure with a drift length of 32 mm and the drifting charge is collected by two arrays of anodes having a pitch of 200 μm. The high-voltage divider is integrated on-board and is realised with p + implantations. For test and calibration purposes, the detector has a new type of MOS injector. The paper presents results obtained to injecting charge at the maximum drift distance (32mm) from the anodes by means of the MOS injecting structure, As front-end electronics, the authors have used a 32-channels low-noise bipolar VLSI circuit (OLA, Omni-purpose Low-noise Amplifer) specifically designed for silicon drift detectors. The uniformity of the drift time in different regions of the sensitive area and its dependence on the ambient temperature are studied

  18. Addressing Criticisms of Large-Scale Marine Protected Areas

    Science.gov (United States)

    Ban, Natalie C; Fernandez, Miriam; Friedlander, Alan M; García-Borboroglu, Pablo; Golbuu, Yimnang; Guidetti, Paolo; Harris, Jean M; Hawkins, Julie P; Langlois, Tim; McCauley, Douglas J; Pikitch, Ellen K; Richmond, Robert H; Roberts, Callum M

    2018-01-01

    Abstract Designated large-scale marine protected areas (LSMPAs, 100,000 or more square kilometers) constitute over two-thirds of the approximately 6.6% of the ocean and approximately 14.5% of the exclusive economic zones within marine protected areas. Although LSMPAs have received support among scientists and conservation bodies for wilderness protection, regional ecological connectivity, and improving resilience to climate change, there are also concerns. We identified 10 common criticisms of LSMPAs along three themes: (1) placement, governance, and management; (2) political expediency; and (3) social–ecological value and cost. Through critical evaluation of scientific evidence, we discuss the value, achievements, challenges, and potential of LSMPAs in these arenas. We conclude that although some criticisms are valid and need addressing, none pertain exclusively to LSMPAs, and many involve challenges ubiquitous in management. We argue that LSMPAs are an important component of a diversified management portfolio that tempers potential losses, hedges against uncertainty, and enhances the probability of achieving sustainably managed oceans. PMID:29731514

  19. Methods for Finding Legacy Wells in Large Areas

    Energy Technology Data Exchange (ETDEWEB)

    Hammack, Richard W. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Veloski, Garret A. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Hodges, D. Greg [Fugro Airborne Surveys, Mississauga, ON (Canada); White, Jr., Curt M. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)

    2016-06-16

    United States. When abandoned, many wells were not adequately sealed and now provide a potential conduit for the vertical movement of liquids and gases. Today, groundwater aquifers can be contaminated by surface pollutants flowing down wells or by deep, saline water diffusing upwards. Likewise, natural gas, carbon dioxide (CO2), or radon can travel upwards via these wells to endanger structures or human health on the surface. Recently, the need to find and plug wells has become critical with the advent of carbon dioxide injection into geologic formations for enhanced oil recovery (EOR) or carbon storage. The potential for natural gas or brine leakage through existing wells has also been raised as a concern in regions where shale resources are hydraulically fractured for hydrocarbon recovery. In this study, the National Energy Technology Laboratory (NETL) updated existing, effective well finding techniques to be able to survey large areas quickly using helicopter or ground-vehicle-mounted magnetometers, combined with mobile methane detection. For this study, magnetic data were collected using airborne and ground vehicles equipped with two boom-mounted magnetometers, or on foot using a hand-held magnetometer with a single sensor. Data processing techniques were employed to accentuate well-casing-type magnetic signatures. To locate wells with no magnetic signature (wells where the steel well casing had been removed), the team monitored for anomalous concentrations of methane, which could indicate migration of volatile compounds from deeper sedimentary strata along a well or fracture pathway. Methane measurements were obtained using the ALPIS DIfferential Absorption Lidar (DIAL) sensor for helicopter surveys and the Apogee leak detection system (LDS) for ground surveys. These methods were evaluated at a 100-year-old oilfield in Wyoming, where a helicopter magnetic survey accurately located 93% of visible wells. In addition, 20% of the wells found by the survey were

  20. Methods for Finding Legacy Wells in Large Areas

    Energy Technology Data Exchange (ETDEWEB)

    Hammack, Richard [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Veloski, Garret [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Hodges, D. Greg [Fugro Airborne Surveys, Mississauga, ON (Canada); White, Jr., Charles E. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)

    2016-06-16

    More than 10 million wells have been drilled during 150 years of oil and gas production in the United States. When abandoned, many wells were not adequately sealed and now provide a potential conduit for the vertical movement of liquids and gases. Today, groundwater aquifers can be contaminated by surface pollutants flowing down wells or by deep, saline water diffusing upwards. Likewise, natural gas, carbon dioxide (CO2), or radon can travel upwards via these wells to endanger structures or human health on the surface. Recently, the need to find and plug wells has become critical with the advent of carbon dioxide injection into geologic formations for enhanced oil recovery (EOR) or carbon storage. The potential for natural gas or brine leakage through existing wells has also been raised as a concern in regions where shale resources are hydraulically fractured for hydrocarbon recovery. In this study, the National Energy Technology Laboratory (NETL) updated existing, effective well finding techniques to be able to survey large areas quickly using helicopter or ground-vehicle-mounted magnetometers, combined with mobile methane detection. For this study, magnetic data were collected using airborne and ground vehicles equipped with two boom-mounted magnetometers, or on foot using a hand-held magnetometer with a single sensor. Data processing techniques were employed to accentuate well-casing-type magnetic signatures. To locate wells with no magnetic signature (wells where the steel well casing had been removed), the team monitored for anomalous concentrations of methane, which could indicate migration of volatile compounds from deeper sedimentary strata along a well or fracture pathway. Methane measurements were obtained using the ALPIS DIfferential Absorption Lidar (DIAL) sensor for helicopter surveys and the Apogee leak detection system (LDS) for ground surveys. These methods were evaluated at a 100-year-old oilfield in Wyoming, where a helicopter magnetic

  1. Large-area landslide susceptibility with optimized slope-units

    Science.gov (United States)

    Alvioli, Massimiliano; Marchesini, Ivan; Reichenbach, Paola; Rossi, Mauro; Ardizzone, Francesca; Fiorucci, Federica; Guzzetti, Fausto

    2017-04-01

    A Slope-Unit (SU) is a type of morphological terrain unit bounded by drainage and divide lines that maximize the within-unit homogeneity and the between-unit heterogeneity across distinct physical and geographical boundaries [1]. Compared to other terrain subdivisions, SU are morphological terrain unit well related to the natural (i.e., geological, geomorphological, hydrological) processes that shape and characterize natural slopes. This makes SU easily recognizable in the field or in topographic base maps, and well suited for environmental and geomorphological analysis, in particular for landslide susceptibility (LS) modelling. An optimal subdivision of an area into a set of SU depends on multiple factors: size and complexity of the study area, quality and resolution of the available terrain elevation data, purpose of the terrain subdivision, scale and resolution of the phenomena for which SU are delineated. We use the recently developed r.slopeunits software [2,3] for the automatic, parametric delineation of SU within the open source GRASS GIS based on terrain elevation data and a small number of user-defined parameters. The software provides subdivisions consisting of SU with different shapes and sizes, as a function of the input parameters. In this work, we describe a procedure for the optimal selection of the user parameters through the production of a large number of realizations of the LS model. We tested the software and the optimization procedure in a 2,000 km2 area in Umbria, Central Italy. For LS zonation we adopt a logistic regression model implemented in an well-known software [4,5], using about 50 independent variables. To select the optimal SU partition for LS zonation, we want to define a metric which is able to quantify simultaneously: (i) slope-unit internal homogeneity (ii) slope-unit external heterogeneity (iii) landslide susceptibility model performance. To this end, we define a comprehensive objective function S, as the product of three

  2. Detections of millisecond pulsars with the FERMI Large Area Telescope

    International Nuclear Information System (INIS)

    Guillemot, L.

    2009-09-01

    The Fermi observatory was launched on June 11, 2008. It hosts the Large Area Telescope (LAT), sensitive to gamma-ray photons from 20 MeV to over 300 GeV. When the LAT began its activity, nine young and energetic pulsars were known in gamma ray range. At least several tens of pulsar detections by the LAT were predicted before launch. The LAT also allowed the study of millisecond pulsars (MSPs), never firmly detected in gamma ray range before Fermi. This thesis first presents the pulsar timing campaign for the LAT, in collaboration with large radio telescopes and X-ray telescopes, allowing for high sensitivity pulsed searches. Furthermore, it lead to quasi-homogeneous coverage of the galactic MSPs, so that the search for pulsations in LAT data for this population of stars was not affected by an a-priori bias. We present a search for pulsations from these objects in LAT data. For the first time, eight galactic MSPs have been detected as sources of pulsed gamma-ray emission over 100 MeV. In addition, a couple of good candidates for future detection are seen. A similar search for globular cluster MSPs was not successful so far. Comparison of the phase-aligned gamma-ray and radio light curves, as well as the spectral shapes, leads to the conclusion that their gamma-ray emission is similar to that of normal pulsars, and is probably produced in the outer-magnetosphere. This discovery suggests that many unresolved gamma-ray sources are unknown MSPs. (author)

  3. Nano/biosensors based on large-area graphene

    Science.gov (United States)

    Ducos, Pedro Jose

    Two dimensional materials have properties that make them ideal for applications in chemical and biomolecular sensing. Their high surface/volume ratio implies that all atoms are exposed to the environment, in contrast to three dimensional materials with most atoms shielded from interactions inside the bulk. Graphene additionally has an extremely high carrier mobility, even at ambient temperature and pressure, which makes it ideal as a transduction device. The work presented in this thesis describes large-scale fabrication of Graphene Field Effect Transistors (GFETs), their physical and chemical characterization, and their application as biomolecular sensors. Initially, work was focused on developing an easily scalable fabrication process. A large-area graphene growth, transfer and photolithography process was developed that allowed the scaling of production of devices from a few devices per single transfer in a chip, to over a thousand devices per transfer in a full wafer of fabrication. Two approaches to biomolecules sensing were then investigated, through nanoparticles and through chemical linkers. Gold and platinum Nanoparticles were used as intermediary agents to immobilize a biomolecule. First, gold nanoparticles were monodispersed and functionalized with thiolated probe DNA to yield DNA biosensors with a detection limit of 1 nM and high specificity against noncomplementary DNA. Second, devices are modified with platinum nanoparticles and functionalized with thiolated genetically engineered scFv HER3 antibodies to realize a HER3 biosensor. Sensors retain the high affinity from the scFv fragment and show a detection limit of 300 pM. We then show covalent and non-covalent chemical linkers between graphene and antibodies. The chemical linker 1-pyrenebutanoic acid succinimidyl ester (pyrene) stacks to the graphene by Van der Waals interaction, being a completely non-covalent interaction. The linker 4-Azide-2,3,5,6-tetrafluorobenzoic acid, succinimidyl ester (azide

  4. Searches for Dark Matter with the Fermi Large Area Telescope

    CERN Multimedia

    CERN. Geneva

    2016-01-01

    The nature of dark matter is a longstanding enigma of physics; it may consist of particles beyond the Standard Model that are still elusive to experiments. Among indirect search techniques, which look for stable products from the annihilation or decay of dark matter particles, or from axions coupling to high-energy photons, observations of the gamma-ray sky have come to prominence over the last few years, because of the excellent sensitivity and full-sky coverage of the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope mission. The LAT energy range from 20 MeV to above 300 GeV is particularly well suited for searching for products of the interactions of dark matter particles. In this talk I will describe targets studied for evidence of dark matter with the LAT, and review the status of searches performed with up to six years of LAT data. I will also discuss the factors that determine the sensitivities of these searches, including the magnitudes of the signals and the relevant backgrounds, c...

  5. Assessing trade-offs in large marine protected areas.

    Science.gov (United States)

    Davies, Tammy E; Epstein, Graham; Aguilera, Stacy E; Brooks, Cassandra M; Cox, Michael; Evans, Louisa S; Maxwell, Sara M; Nenadovic, Mateja; Ban, Natalie C

    2018-01-01

    Large marine protected areas (LMPAs) are increasingly being established and have a high profile in marine conservation. LMPAs are expected to achieve multiple objectives, and because of their size are postulated to avoid trade-offs that are common in smaller MPAs. However, evaluations across multiple outcomes are lacking. We used a systematic approach to code several social and ecological outcomes of 12 LMPAs. We found evidence of three types of trade-offs: trade-offs between different ecological resources (supply trade-offs); trade-offs between ecological resource conditions and the well-being of resource users (supply-demand trade-offs); and trade-offs between the well-being outcomes of different resource users (demand trade-offs). We also found several divergent outcomes that were attributed to influences beyond the scope of the LMPA. We suggest that despite their size, trade-offs can develop in LMPAs and should be considered in planning and design. LMPAs may improve their performance across multiple social and ecological objectives if integrated with larger-scale conservation efforts.

  6. Calibration of large area Micromegas using cosmic rays

    Energy Technology Data Exchange (ETDEWEB)

    Loesel, Philipp; Biebel, Otmar; Bortfeldt, Jonathan; Flierl, Bernhard; Hertenberger, Ralf; Mueller, Ralph [LMU Muenchen (Germany); Zibell, Andre [JMU Wuerzburg (Germany)

    2016-07-01

    The high luminosity upgrade of the LHC storage ring implies an upgrade of the Muon Spectrometer of the ATLAS experiment. The presently installed detectors of the inner end-cap region cannot cope with the increased background situation and will be replaced by Micromegas and sTGC detectors. Before installation at CERN, the 2 m{sup 2} sized Micromegas quadruplets (SM2) built in Germany will be calibrated. The LMU Cosmic Ray Measurement Facility (CRF) consists of two Monitored Drift Tube chambers (MDT) with an active area of about 9 m{sup 2} for muon tracking and two trigger hodoscopes with sub-ns time-resolution and with additional position information along the wires of the MDTs. With an angular acceptance of -30 to +30 the CRF allows for centroidal or μTPC position determination and thus for calibration in three dimensions. Of particular interest are potential deviations in the micro pattern readout structures or potential deformations of the whole detector. The Performance of the CRF is presently investigated using a telescope of a 1 m{sup 2} and three 100 cm{sup 2} resistive strip Micromegas. We report on the differences in performance between large and small detectors, report on homogeneity of efficiency and pulse height, and present results on deformation and performance of the 1 m{sup 2} Micromegas.

  7. Fermi Large Area Telescope Operations: Progress Over 4 Years

    Energy Technology Data Exchange (ETDEWEB)

    Cameron, Robert A.; /SLAC

    2012-06-28

    The Fermi Gamma-ray Space Telescope was launched into orbit in June 2008, and is conducting a multi-year gamma-ray all-sky survey, using the main instrument on Fermi, the Large Area Telescope (LAT). Fermi began its science mission in August 2008, and has now been operating for almost 4 years. The SLAC National Accelerator Laboratory hosts the LAT Instrument Science Operations Center (ISOC), which supports the operation of the LAT in conjunction with the Mission Operations Center (MOC) and the Fermi Science Support Center (FSSC), both at NASA's Goddard Space Flight Center. The LAT has a continuous output data rate of about 1.5 Mbits per second, and data from the LAT are stored on Fermi and transmitted to the ground through TDRS and the MOC to the ISOC about 10 times per day. Several hundred computers at SLAC are used to process LAT data to perform event reconstruction, and gamma-ray photon data are subsequently delivered to the FSSC for public release with a few hours of being detected by the LAT. We summarize the current status of the LAT, and the evolution of the data processing and monitoring performed by the ISOC during the first 4 years of the Fermi mission, together with future plans for further changes to detected event data processing and instrument operations and monitoring.

  8. Large-Area, Ensemble Molecular Electronics: Motivation and Challenges.

    Science.gov (United States)

    Vilan, Ayelet; Aswal, Dinesh; Cahen, David

    2017-03-08

    We review charge transport across molecular monolayers, which is central to molecular electronics (MolEl), using large-area junctions (NmJ). We strive to provide a wide conceptual overview of three main subtopics. First, a broad introduction places NmJ in perspective to related fields of research and to single-molecule junctions (1mJ) in addition to a brief historical account. As charge transport presents an ultrasensitive probe for the electronic perfection of interfaces, in the second part ways to form both the monolayer and the contacts are described to construct reliable, defect-free interfaces. The last part is dedicated to understanding and analyses of current-voltage (I-V) traces across molecular junctions. Notwithstanding the original motivation of MolEl, I-V traces are often not very sensitive to molecular details and then provide a poor probe for chemical information. Instead, we focus on how to analyze the net electrical performance of molecular junctions, from a functional device perspective. Finally, we point to creation of a built-in electric field as a key to achieve functionality, including nonlinear current-voltage characteristics that originate in the molecules or their contacts to the electrodes. This review is complemented by a another review that covers metal-molecule-semiconductor junctions and their unique hybrid effects.

  9. Large area CNT-Si heterojunction for photodetection

    Energy Technology Data Exchange (ETDEWEB)

    Aramo, C., E-mail: aramo@na.infn.it [INFN, Sezione di Napoli, Via Cintia 2, 80126 Napoli (Italy); Ambrosio, M.; Bonavolontà, C. [INFN, Sezione di Napoli, Via Cintia 2, 80126 Napoli (Italy); Boscardin, M.; Crivellari, M. [Centro per Materiali e i Microsistemi Fondazione Bruno Kessler (FBK), Via Sommarive 18, Povo di Trento, 38123 Trento (Italy); Lisio, C. de [INFN, Sezione di Napoli, Via Cintia 2, 80126 Napoli (Italy); Dip. Scienze Fisiche, Università degli Studi di Napoli “Federico II”, Via Cintia 2, 80126 Napoli (Italy); Grossi, V. [INFN, Sezione di L' Aquila and Dip. Scienze Fisiche e Chimiche, Università degli Studi dell' Aquila, Via Vetoio, Coppito, 67100 L' Aquila (Italy); Maddalena, P. [INFN, Sezione di Napoli, Via Cintia 2, 80126 Napoli (Italy); Dip. Scienze Fisiche, Università degli Studi di Napoli “Federico II”, Via Cintia 2, 80126 Napoli (Italy); Passacantando, M. [INFN, Sezione di L' Aquila and Dip. Scienze Fisiche e Chimiche, Università degli Studi dell' Aquila, Via Vetoio, Coppito, 67100 L' Aquila (Italy); Valentino, M. [CNR-SPIN UOS di Napoli, Via Cintia 2, 80126 Napoli (Italy)

    2017-02-11

    Multiwall carbon nanotubes (MWCNTs) consist of multiple layers of graphite sheets arranged in concentric cylinders, from two to many tens. These systems are closely related to graphite layers but in some features, MWCNTs behave quite differently from graphite. In particular, their ability to generate a photocurrent in a wide wavelength range has been demonstrated either without or with the application of a draining voltage. In addition, the photocurrent signal has been found to reproduce the optical absorbance of MWCNTs, showing a maximum in the near UV region. In this paper main characteristics of a novel large area photodetector featuring low noise, high linearity and efficiency are reported. This detector has been obtained by coupling the optoelectronic characteristics of MWCNTs with the well-known properties of silicon. MWCNTs are growth on n-doped silicon layer by chemical vapour deposition creating a p–n heterojunction with high sensitivity to the radiation from UV to IR. An additional MIS junction is obtained with a metallic conductive layer deposited on the back of silicon substrate. Moreover, first results on the signals generated by pulsed laser are also reported.

  10. A Prototype Large Area Detector Module for Muon Scattering Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Steer, C.A.; Boakes, J.; Burns, J.; Snow, S.; Stapleton, M.; Thompson, L.F.; Quillin, S. [AWE Aldermaston, Reading, Berkshire, RG7 4PR (United Kingdom)

    2015-07-01

    Abstract-Shielded special nuclear materials (SNM) are of concern as some fissile isotopes have low gamma and neutron emission rates. These materials are also easily shielded to the point where their passive emissions are comparable to background. Consequently, shielded SNM is very challenging for passive radiation detection portals which scan cargo containers. One potential solution for this is to utilise the natural cosmic ray muon background and examine how these muons scatter from materials inside the container volume, terms; the muon scattering tomography (MST) technique measures the three-dimensional localised scattering at all points within a cargo container, providing a degree of material discrimination. There is the additional benefit that the MST signal increases with the presence of more high density shielding materials, in contrast to passive radiation detection. Simulations and calculations suggest that the effectiveness of the technique is sensitive to the tracking accuracy amongst other parameters, motivating the need to develop practical detector systems that are capable of tracking cosmic ray muons. To this end, we have constructed and tested a 2 m by 2 m demonstration module based on gaseous drift chambers and triggered by a large area scintillator-based detector, which is readout by wavelength shifting fibres. We discuss its design, construction, characterisation and operational challenges. (authors)

  11. FERMI LARGE AREA TELESCOPE OBSERVATION OF SUPERNOVA REMNANT S147

    Energy Technology Data Exchange (ETDEWEB)

    Katsuta, J.; Uchiyama, Y.; Tanaka, T.; Tajima, H.; Bechtol, K.; Funk, S.; Lande, J. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Ballet, J. [Laboratoire AIM, CEA-IRFU/CNRS/Universite Paris Diderot, Service d' Astrophysique, CEA Saclay, 91191 Gif sur Yvette (France); Hanabata, Y. [Department of Physical Sciences, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Lemoine-Goumard, M. [Universite Bordeaux 1, CNRS/IN2p3, Centre d' Etudes Nucleaires de Bordeaux Gradignan, 33175 Gradignan (France); Takahashi, T., E-mail: katsuta@slac.stanford.edu, E-mail: uchiyama@slac.stanford.edu [Institute of Space and Astronautical Science, Japanese Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan)

    2012-06-20

    We present an analysis of gamma-ray data obtained with the Large Area Telescope on board the Fermi Gamma-ray Space Telescope in the region around supernova remnant (SNR) S147 (G180.0-1.7). A spatially extended gamma-ray source detected in an energy range of 0.2-10 GeV is found to coincide with SNR S147. We confirm its spatial extension at >5{sigma} confidence level. The gamma-ray flux is (3.8 {+-} 0.6) Multiplication-Sign 10{sup -8} photons cm{sup -2} s{sup -1}, corresponding to a luminosity of 1.3 Multiplication-Sign 10{sup 34} (d/1.3 kpc){sup 2} erg s{sup -1} in this energy range. The gamma-ray emission exhibits a possible spatial correlation with the prominent H{alpha} filaments of SNR S147. There is no indication that the gamma-ray emission comes from the associated pulsar PSR J0538+2817. The gamma-ray spectrum integrated over the remnant is likely dominated by the decay of neutral {pi} mesons produced through the proton-proton collisions in the filaments. The reacceleration of the pre-existing cosmic rays and subsequent adiabatic compression in the filaments is sufficient to provide the energy density required of high-energy protons.

  12. FERMI LARGE AREA TELESCOPE OBSERVATIONS OF THE VELA PULSAR

    International Nuclear Information System (INIS)

    Abdo, A. A.; Ackermann, M.; Bartelt, J.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Bogart, J. R.; Atwood, W. B.; Bagagli, R.; Baldini, L.; Bellardi, F.; Bellazzini, R.; Ballet, J.; Band, D. L.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Bisello, D.; Baughman, B. M.

    2009-01-01

    The Vela pulsar is the brightest persistent source in the GeV sky and thus is the traditional first target for new γ-ray observatories. We report here on initial Fermi Large Area Telescope observations during verification phase pointed exposure and early sky survey scanning. We have used the Vela signal to verify Fermi timing and angular resolution. The high-quality pulse profile, with some 32,400 pulsed photons at E ≥ 0.03 GeV, shows new features, including pulse structure as fine as 0.3 ms and a distinct third peak, which shifts in phase with energy. We examine the high-energy behavior of the pulsed emission; initial spectra suggest a phase-averaged power-law index of Γ = 1.51 +0.05 -0.04 with an exponential cutoff at E c = 2.9 ± 0.1 GeV. Spectral fits with generalized cutoffs of the form e -(E/E c ) b require b ≤ 1, which is inconsistent with magnetic pair attenuation, and thus favor outer-magnetosphere emission models. Finally, we report on upper limits to any unpulsed component, as might be associated with a surrounding pulsar wind nebula.

  13. Large area self-powered gamma ray detector

    International Nuclear Information System (INIS)

    LeVert, F.E.

    1994-01-01

    The purpose of this research was to develop a large area self-powered gamma detector (LASPGD) capable of detecting the movement of sealed radiation sources into and out of industrial radiographic units and to construct a prototype source position monitor (SPM) for these units utilizing the LASPGD. Prototype isotropic and directional LASPGDs, with solid and inert gas dielectrics, were developed and extensively tested using calibrated gamma sources (i.e., Cs-137, and Co-60). The sensitivities of the isotropic detectors, with inert gas dielectrics, were found to be approximately a factor of ten greater than those measured for the solid dielectric LASPGDs. Directionally sensitive self-powered detectors were found to exhibit a forward-to-back hemispherical sensitivity ratio of approximately 2 to 1. Industrial radiographic units containing Ir-192 sources with different activities were used to test the performance of the SPM. The SPM, which utilized a gas dielectric LASPGD, performed as designed. That is, the current generated in the LASPGD was converted to a voltage, amplified and used to control the on/off state of an incandescent lamp. The incandescent lamp, which functions as the source/out warning indicator, flashes at a rate of one flash per second when the source is in use (i.e. out of its shield)

  14. Large area imaging of forensic evidence with MA-XRF.

    Science.gov (United States)

    Langstraat, Kirsten; Knijnenberg, Alwin; Edelman, Gerda; van de Merwe, Linda; van Loon, Annelies; Dik, Joris; van Asten, Arian

    2017-11-08

    This study introduces the use of macroscopic X-ray fluorescence (MA-XRF) for the detection, classification and imaging of forensic traces over large object areas such as entire pieces of clothing and wall paneling. MA-XRF was sufficiently sensitive and selective to detect human biological traces like blood, semen, saliva, sweat and urine on fabric on the basis of Fe, Zn, K, Cl and Ca elemental signatures. With MA-XRF a new chemical contrast is introduced for human stain detection and this can provide a valuable alternative when the evidence item is challenging for conventional techniques. MA-XRF was also successfully employed for the chemical imaging and classification of gunshot residues (GSR). The full and non-invasive elemental mapping (Pb, Ba, Sr, K and Cl) of intact pieces of clothing allows for a detailed shooting incident reconstruction linking firearms and ammunition to point of impact and providing information on the shooting angle. In high resolution mode MA-XRF can even be used to provide information on the shooting order of different ammunition types. Finally, by using the surface penetration of X-rays we demonstrate that the lead signature of a bullet impact can be easily detected even if covered by multiple layers of wall paint or human blood.

  15. MONITORING OF LARGE INSTABLE AREAS: system reliability and new tools.

    Science.gov (United States)

    Leandro, G.; Mucciarelli, M.; Pellicani, R.; Spilotro, G.

    2009-04-01

    The monitoring of unstable or potentially unstable areas is a necessary operation every time you can not remove the conditions of risk and apply to mitigation measures. In Italian Apennine regions there are many urban or extra-urban areas affected by instability, for which it is impracticable to remove hazard conditions, because of size and cost problems. The technological evolution exportable to the field of land instability monitoring is particularly lively and allows the use of warning systems unthinkable just few years ago. However, the monitoring of unstable or potentially unstable areas requires a very great knowledge of the specific problems, without which the reliability of the system may be dangerously overestimated. The movement may arise, indeed, in areas not covered by instrumentation, or covered with vegetation that prevents the acquisition of both reflected signals in the multi-beam laser techniques and radar signals. Environmental conditions (wind, concentrated sources of light, temperature changes, presence of animals) may also invalidate the accuracy of the measures, by introducing modulations or disturbance at a level well above the threshold of alarm signal, leading consequently to raise the values of the warning threshold. The Authors have gained long experience with the observation and monitoring of some large landslides in the Southern Apennine (Aliano, Buoninventre, Calciano, Carlantino, etc.) and unstable areas also at regional scale. One of the most important experiences is about the case of landslides of extensive areas, where unstable and stables zones coexist along transverse and longitudinal axis. In many of these cases you need the accurate control of the movement at selected points to evaluate the trend of displacement velocity, which can be achieved by means of a single-beam laser. The control of these movements, however, does not provide information on stress pattern into the stable areas. Among the sensitive precursors, acoustic

  16. Exploring Milkyway Halo Substructures with Large-Area Sky Surveys

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ting [Texas A & M Univ., College Station, TX (United States)

    2016-01-01

    Over the last two decades, our understanding of the Milky Way has been improved thanks to large data sets arising from large-area digital sky surveys. The stellar halo is now known to be inhabited by a variety of spatial and kinematic stellar substructures, including stellar streams and stellar clouds, all of which are predicted by hierarchical Lambda Cold Dark Matter models of galaxy formation. In this dissertation, we first present the analysis of spectroscopic observations of individual stars from the two candidate structures discovered using an M-giant catalog from the Two Micron All-Sky Survey. The follow-up observations show that one of the candidates is a genuine structure which might be associated with the Galactic Anticenter Stellar Structure, while the other one is a false detection due to the systematic photometric errors in the survey or dust extinction in low Galactic latitudes. We then presented the discovery of an excess of main sequence turn-off stars in the direction of the constellations of Eridanus and Phoenix from the first-year data of the Dark Energy Survey (DES) – a five-year, 5,000 deg2 optical imaging survey in the Southern Hemisphere. The Eridanus-Phoenix (EriPhe) overdensity is centered around l ~ 285° and b ~ -60° and the Poisson significance of the detection is at least 9σ. The EriPhe overdensity has a cloud-like morphology and the extent is at least ~ 4 kpc by ~ 3 kpc in projection, with a heliocentric distance of about d ~ 16 kpc. The EriPhe overdensity is morphologically similar to the previously-discovered Virgo overdensity and Hercules-Aquila cloud. These three overdensities lie along a polar plane separated by ~ 120° and may share a common origin. In addition to the scientific discoveries, we also present the work to improve the photometric calibration in DES using auxiliary calibration systems, since the photometric errors can cause false detection in first the halo substructure. We present a detailed description of the two

  17. A large area cooled-CCD detector for electron microscopy

    International Nuclear Information System (INIS)

    Faruqi, A.R.; Andrews, H.N.; Raeburn, C.

    1994-01-01

    Large area cooled-CCDs are an excellent medium for (indirectly) recording electron images and electron diffraction patterns in real time and for use in electron tomography; real-time imaging is extremely useful in making rapid adjustments in the electron microscope. CCDs provide high sensitivity (useful for minimising dosage to radiation-sensitive biological specimen), good resolution, stable performance, excellent dynamic range and linearity and a reasonably fast readout.We have built an electron imaging device based on the EEV 1152 by 814 pixel CCD which is controlled from a unix based SUN Sparcstation operating under X-Windows. The incident 100 kV electrons are converted to visible light in a 0.5 mm thick YAG single crystal which is imaged through a lens on to the CCD.The CCD electronics is designed to be as flexible as possible and allows a wide variation in the readout speed to cater for the relatively fast application where readout noise is less critical and low readout noise applications where the extra few seconds of readout time are not significant. The CCD electronics is built in VME format which is controlled through a S-bus to VME driver. With two parallel channels of readout the whole image can be read out in similar 1 s (using the faster readout speed) with 16 bit precision and the image is displayed under X-Windows in a few seconds. The present readout works at 500 kHz and has a noise of similar 30 e rms per pixel. With a Peltier cooling device we can operate the CCD at similar -40 circle C which reduces the dark current adequately to allow exposures of up to several minutes. Several examples of patterns collected with the system on a Philips CM12 microscope will be presented. ((orig.))

  18. Evaluating biodiversity conservation around a large Sumatran protected area.

    Science.gov (United States)

    Linkie, Matthew; Smith, Robert J; Zhu, Yu; Martyr, Deborah J; Suedmeyer, Beth; Pramono, Joko; Leader-Williams, Nigel

    2008-06-01

    Many of the large, donor-funded community-based conservation projects that seek to reduce biodiversity loss in the tropics have been unsuccessful. There is, therefore, a need for empirical evaluations to identify the driving factors and to provide evidence that supports the development of context-specific conservation projects. We used a quantitative approach to measure, post hoc, the effectiveness of a US$19 million Integrated Conservation and Development Project (ICDP) that sought to reduce biodiversity loss through the development of villages bordering Kerinci Seblat National Park, a UNESCO World Heritage Site in Indonesia. We focused on the success of the ICDP component that disbursed a total of US$1.5 million through development grants to 66 villages in return for their commitment to stop illegally clearing the forest. To investigate whether the ICDP lowered deforestation rates in focal villages, we selected a subset of non-ICDP villages that had similar physical and socioeconomic features and compared their respective deforestation rates. Village participation in the ICDP and its development schemes had no effect on deforestation. Instead, accessible areas where village land-tenure had been undermined by the designation of selective-logging concessions tended to have the highest deforestation rates. Our results indicate that the goal of the ICDP was not met and, furthermore, suggest that both law enforcement inside the park and local property rights outside the park need to be strengthened. Our results also emphasize the importance of quantitative approaches in helping to inform successful and cost-effective strategies for tropical biodiversity conservation.

  19. Neutral processes forming large clones during colonization of new areas.

    Science.gov (United States)

    Rafajlović, M; Kleinhans, D; Gulliksson, C; Fries, J; Johansson, D; Ardehed, A; Sundqvist, L; Pereyra, R T; Mehlig, B; Jonsson, P R; Johannesson, K

    2017-08-01

    In species reproducing both sexually and asexually clones are often more common in recently established populations. Earlier studies have suggested that this pattern arises due to natural selection favouring generally or locally successful genotypes in new environments. Alternatively, as we show here, this pattern may result from neutral processes during species' range expansions. We model a dioecious species expanding into a new area in which all individuals are capable of both sexual and asexual reproduction, and all individuals have equal survival rates and dispersal distances. Even under conditions that favour sexual recruitment in the long run, colonization starts with an asexual wave. After colonization is completed, a sexual wave erodes clonal dominance. If individuals reproduce more than one season, and with only local dispersal, a few large clones typically dominate for thousands of reproductive seasons. Adding occasional long-distance dispersal, more dominant clones emerge, but they persist for a shorter period of time. The general mechanism involved is simple: edge effects at the expansion front favour asexual (uniparental) recruitment where potential mates are rare. Specifically, our model shows that neutral processes (with respect to genotype fitness) during the population expansion, such as random dispersal and demographic stochasticity, produce genotype patterns that differ from the patterns arising in a selection model. The comparison with empirical data from a post-glacially established seaweed species (Fucus radicans) shows that in this case, a neutral mechanism is strongly supported. © 2017 The Authors. Journal of Evolutionary Biology Published by John Wiley & Sons ltd on Behalf of European Society for Evolutionary Biology.

  20. THE SPITZER -HETDEX EXPLORATORY LARGE-AREA SURVEY

    Energy Technology Data Exchange (ETDEWEB)

    Papovich, C.; Shipley, H. V.; Mehrtens, N.; Lanham, C.; DePoy, D. L.; Kawinwanichakij, L. [Department of Physics and Astronomy, Texas A and M University, College Station, TX, 77843-4242 (United States); Lacy, M. [North American ALMA Science Center, NRAO Headquarters, Charlottesville, VA 22903 (United States); Ciardullo, R.; Gronwall, C. [Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States); Finkelstein, S. L.; Drory, N.; Gebhardt, K.; Hill, G. J.; Jogee, S. [Department of Astronomy, The University of Texas at Austin, Austin, TX 78712 (United States); Bassett, R. [International Centre for Radio Astronomy Research, University of Western Australia, 7 Fairway, Crawley, WA 6009 (Australia); Behroozi, P. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Blanc, G. A. [Departamento de Astronomía, Universidad de Chile, Camino del Observatorio 1515, Las Condes, Santiago (Chile); Jong, R. S. de [Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany); Gawiser, E. [Department of Physics and Astronomy, Rutgers, The State University of New Jersey, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States); Hopp, U., E-mail: papovich@physics.tamu.edu, E-mail: papovich@tamu.edu [Max-Planck-Institut für Extraterrestrische Physik, D-85741, Garching (Germany); and others

    2016-06-01

    We present post-cryogenic Spitzer imaging at 3.6 and 4.5 μ m with the Infrared Array Camera (IRAC) of the Spitzer /HETDEX Exploratory Large-Area (SHELA) survey. SHELA covers ≈24 deg{sup 2} of the Sloan Digital Sky Survey “Stripe 82” region, and falls within the footprints of the Hobby–Eberly Telescope Dark Energy Experiment (HETDEX) and the Dark Energy Survey. The HETDEX blind R ∼ 800 spectroscopy will produce ∼200,000 redshifts from the Ly α emission for galaxies in the range 1.9 <  z  < 3.5, and an additional ∼200,000 redshifts from the [O ii] emission for galaxies at z  < 0.5. When combined with deep ugriz images from the Dark Energy Camera, K -band images from NEWFIRM, and other ancillary data, the IRAC photometry from Spitzer will enable a broad range of scientific studies of the relationship between structure formation, galaxy stellar mass, halo mass, the presence of active galactic nuclei, and environment over a co-moving volume of ∼0.5 Gpc{sup 3} at 1.9 <  z  < 3.5. Here, we discuss the properties of the SHELA IRAC data set, including the data acquisition, reduction, validation, and source catalogs. Our tests show that the images and catalogs are 80% (50%) complete to limiting magnitudes of 22.0 (22.6) AB mag in the detection image, which is constructed from the weighted sum of the IRAC 3.6 and 4.5 μ m images. The catalogs reach limiting sensitivities of 1.1  μ Jy at both 3.6 and 4.5 μ m (1 σ , for R = 2″ circular apertures). As a demonstration of the science, we present IRAC number counts, examples of highly temporally variable sources, and galaxy surface density profiles of rich galaxy clusters. In the spirit of the Spitzer Exploratory programs, we provide all of the images and catalogs as part of the publication.

  1. THE SPITZER -HETDEX EXPLORATORY LARGE-AREA SURVEY

    International Nuclear Information System (INIS)

    Papovich, C.; Shipley, H. V.; Mehrtens, N.; Lanham, C.; DePoy, D. L.; Kawinwanichakij, L.; Lacy, M.; Ciardullo, R.; Gronwall, C.; Finkelstein, S. L.; Drory, N.; Gebhardt, K.; Hill, G. J.; Jogee, S.; Bassett, R.; Behroozi, P.; Blanc, G. A.; Jong, R. S. de; Gawiser, E.; Hopp, U.

    2016-01-01

    We present post-cryogenic Spitzer imaging at 3.6 and 4.5 μ m with the Infrared Array Camera (IRAC) of the Spitzer /HETDEX Exploratory Large-Area (SHELA) survey. SHELA covers ≈24 deg 2 of the Sloan Digital Sky Survey “Stripe 82” region, and falls within the footprints of the Hobby–Eberly Telescope Dark Energy Experiment (HETDEX) and the Dark Energy Survey. The HETDEX blind R ∼ 800 spectroscopy will produce ∼200,000 redshifts from the Ly α emission for galaxies in the range 1.9 <  z  < 3.5, and an additional ∼200,000 redshifts from the [O ii] emission for galaxies at z  < 0.5. When combined with deep ugriz images from the Dark Energy Camera, K -band images from NEWFIRM, and other ancillary data, the IRAC photometry from Spitzer will enable a broad range of scientific studies of the relationship between structure formation, galaxy stellar mass, halo mass, the presence of active galactic nuclei, and environment over a co-moving volume of ∼0.5 Gpc 3 at 1.9 <  z  < 3.5. Here, we discuss the properties of the SHELA IRAC data set, including the data acquisition, reduction, validation, and source catalogs. Our tests show that the images and catalogs are 80% (50%) complete to limiting magnitudes of 22.0 (22.6) AB mag in the detection image, which is constructed from the weighted sum of the IRAC 3.6 and 4.5 μ m images. The catalogs reach limiting sensitivities of 1.1  μ Jy at both 3.6 and 4.5 μ m (1 σ , for R = 2″ circular apertures). As a demonstration of the science, we present IRAC number counts, examples of highly temporally variable sources, and galaxy surface density profiles of rich galaxy clusters. In the spirit of the Spitzer Exploratory programs, we provide all of the images and catalogs as part of the publication.

  2. Index-antiguided planar waveguide lasers with large mode area

    Science.gov (United States)

    Liu, Yuanye

    The on-going research and application interests with high power large-mode-area (LMA) waveguide lasers, especially in fiber geometry, at the beginning of this century drive the development of many novel waveguide designs. Index antiguiding, proposed by Siegman in 2003, is among one of them. The goal for index antiguiding is to introduce transversal modal loss with the relative simple waveguide design while maintain single transverse mode operation for good beam quality. The idea which is selectively support of fundamental mode is facilitated by involving certain level of signal regeneration inside the waveguide core. Since the modal loss is closed associated with waveguide design parameters such as core size and refractive index, the amount of gain inside the core provides active control of transverse modes inside index-antiguiding waveguide. For example, fundamental transverse mode inside such waveguide can be excited and propagate lossless when sufficient optical gain is provided. This often requires doped waveguide core and optical pumping at corresponding absorption band. However, the involvement of optical pumping also has its consequences. Phenomena such as thermal-optic effect and gain spatial hole-burning which are commonly found in bulk lasers request attention when scaling up output power with LMA index-antiguided waveguide amplifiers and resonators. In response, three key challenges of index-antiguided planar waveguide lasers, namely, guiding mechanism, power efficiency and transverse mode discrimination, are analyzed theoretically and experimentally in this dissertation. Experiments are based on two index-antiguided planar waveguide chips, whose core thickness are 220 microm and 400 microm respectively. The material of waveguide core is 1% Neodymium-doped Yttrium Aluminium garnet, or Nd:YAG while the cladding is made from Terbium Gallium garnet, or TGG. Due to the face pumping and limited pump power, it is found, with 220 microm-thick-core chip, that

  3. Plan for support of large-plant (post-CRBR) needs in large-leak sodium-water reaction area

    International Nuclear Information System (INIS)

    Whipple, J.C.

    1980-03-01

    Work in the large leak test and analysis area of steam generator development has been carried out at GE-ARSD under 189a SG037 since 1973. The currently planned master schedule for the SG037 program is shown. Principal activities are the large leak testing program being carried out at the Large Leak Test Rig and the analysis methods development. The plan for supporting the large plant (post-CRBR) needs in the large leak sodium-water reaction area is outlined. Most of the needs will be answered in the current SG037 large leak program

  4. Four large coastal upwelling areas are created by eastern boundary ...

    African Journals Online (AJOL)

    spamer

    large deep-water hake Merluccius paradoxus, 2.7% small M. paradoxus, 1.3% ... hake in the Benguela region, the shallow-water species. Merluccius capensis .... sharks are not included in the estimate, and neither is the proportion of sharks ...

  5. Irradiation of large area Mylar membrane and characterization of ...

    Indian Academy of Sciences (India)

    Unknown

    of its energy in areas away from the trajectory or just de- excites in time depending on the type of material. In insu- lators electronic excitation can induce extended defects along the ion path due to the secondary ionization (Mehta. 1996). Many polymers are able to recover the track halo up to a certain limit of the order of a ...

  6. Avian surveys of large geographical areas: A systematic approach

    Science.gov (United States)

    Scott, J.M.; Jacobi, J.D.; Ramsey, F.L.

    1981-01-01

    A multidisciplinary team approach was used to simultaneously map the distribution of birds, selected food items, and major vegetation types in 34,000- to 140,000-ha tracts in native Hawaiian forests. By using a team approach, large savings in time can be realized over attempts to conduct similar surveys of smaller scope, and a systems approach to management problems is made easier. The methods used in survey design, training observers, and documenting bird numbersand habitat descriptions are discussed in detail.

  7. Performance of the Antares large area cold cathode electron gun

    International Nuclear Information System (INIS)

    Rosocha, L.A.; Mansfield, C.R.

    1983-01-01

    The performance of the electron gun which supplies ionization for the Antares high-power electron-beam-sustained CO 2 -laser power amplifier is described. This electron gun is a coaxial cylindrical cold cathode vacuum triode having a total electron aperture area of approximately 9 m 2 . Electrons are extracted from the gun in pulses of 3 to 6 μs duration, average current densities of 40 to 60 mA/cm 2 , and electron energies of 450 to 500 keV. The main areas of discussion in this paper are the performance in terms of grid control, current-density balance, and current runaway due to breakdown limitations. Comparison of the experimental results with the predictions of a theoretical model for the electron gun are also presented

  8. Performance of the Antares large area cold cathode electron gun

    International Nuclear Information System (INIS)

    Rosocha, L.A.; Mansfield, C.R.

    1983-01-01

    The performance of the electron gun which supplies ionization for the Antares high power electron beam sustained CO 2 laser power amplifier is described. This electron gun is a coaxial cylindrical cold cathode vacuum triode having a total electron aperture area of approximately 9 m 2 . Electrons are extracted from the gun in pulses of 3-6 μs duration, average current densities of 40-60 ma/cm2, and electron energies of 450-500 keV. The main areas of discussion in this paper are the performance in terms of grid control, current density balance, and current runaway due to breakdown limitations. Comparison of the experimental results with the predictions of a theoretical model for the electron gun will also be presented

  9. Monitoring gamma radioactivity over large land areas using portable equipment

    International Nuclear Information System (INIS)

    Mac Mahon, T.D.; Gray, P.W.; Eer, A.M. D'; Naboulsi, A.H.; Koutsoyannopoulos, C.

    1990-01-01

    The principal objective of this research has been to provide information on cost-effective techniques to detect localized areas of gamma-emitting radionuclides. This objective has been achieved by determining the time required to scan unit area as a function of depth of the gamma source below the site surface, the activity of the gamma source, the energy of the emitted gamma-ray, and the gamma transport properties of the site material. A comparison between survey and sampling techniques is made, and the advantages of using survey techniques to detect localized gamma-ray sources are discussed. A survey technique based on an adaptive moving array detector system is described. A field experiment has been carried out to verify the results of calculations of the sensitivity of the techniques described

  10. A large area transition radiation detector for the NOMAD experiment

    Science.gov (United States)

    Bassompierre, G.; Bermond, M.; Berthet, M.; Bertozzi, T.; Détraz, C.; Dubois, J.-M.; Dumps, L.; Engster, C.; Fazio, T.; Gaillard, G.; Gaillard, J.-M.; Gouanère, M.; Manola-Poggioli, E.; Mossuz, L.; Mendiburu, J.-P.; Nédélec, P.; Palazzini, E.; Pessard, H.; Petit, P.; Petitpas, P.; Placci, A.; Sillou, D.; Sottile, R.; Valuev, V.; Verkindt, D.; Vey, H.; Wachnik, M.

    1998-02-01

    A transition radiation detector to identify electrons at 90% efficiency with a rejection factor against pions of 10 3 on an area of 2.85 × 2.85 m 2 has been constructed for the NOMAD experiment. Each of its 9 modules includes a 315 plastic foil radiator and a detector plane of 176 vertical straw tubes filled with a xenon-methane gas mixture. Details of the design, construction and operation of the detector are given.

  11. A large area transition radiation detector for the NOMAD experiment

    CERN Document Server

    Bassompierre, Gabriel; Berthet, M; Bertozzi, T; Détraz, C; Dubois, J M; Dumps, Ludwig; Engster, Claude; Fazio, T; Gaillard, G; Gaillard, Jean-Marc; Gouanère, M; Manola-Poggioli, E; Mossuz, L; Mendiburu, J P; Nédélec, P; Palazzini, E; Pessard, H; Petit, P; Petitpas, P; Placci, Alfredo; Sillou, D; Sottile, R; Valuev, V Yu; Verkindt, D; Vey, H; Wachnik, M

    1997-01-01

    A transition radiation detector to identify electrons at 90% efficiency with a rejection factor against pions of 10 3 on an area of 2.85 × 2.85 m 2 has been constructed for the NOMAD experiment. Each of its 9 modules includes a 315 plastic foil radiator and a detector plane of 176 vertical straw tubes filled with a xenon-methane gas mixture. Details of the design, construction and operation of the detector are given.

  12. Development of large area, high efficiency amorphous silicon solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, K.S.; Kim, S.; Kim, D.W. [Yu Kong Taedok Institute of Technology (Korea, Republic of)

    1996-02-01

    The objective of the research is to develop the mass-production technologies of high efficiency amorphous silicon solar cells in order to reduce the costs of solar cells and dissemination of solar cells. Amorphous silicon solar cell is the most promising option of thin film solar cells which are relatively easy to reduce the costs. The final goal of the research is to develop amorphous silicon solar cells having the efficiency of 10%, the ratio of light-induced degradation 15% in the area of 1200 cm{sup 2} and test the cells in the form of 2 Kw grid-connected photovoltaic system. (author) 35 refs., 8 tabs., 67 figs.

  13. Progress in amorphous silicon based large-area multijunction modules

    Science.gov (United States)

    Carlson, D. E.; Arya, R. R.; Bennett, M.; Chen, L.-F.; Jansen, K.; Li, Y.-M.; Maley, N.; Morris, J.; Newton, J.; Oswald, R. S.; Rajan, K.; Vezzetti, D.; Willing, F.; Yang, L.

    1996-01-01

    Solarex, a business unit of Amoco/Enron Solar, is scaling up its a-Si:H/a-SiGe:H tandem device technology for the production of 8 ft2 modules. The current R&D effort is focused on improving the performance, reliability and cost-effectiveness of the tandem junction technology by systematically optimizing the materials and interfaces in small-area single- and tandem junction cells. Average initial conversion efficiencies of 8.8% at 85% yield have been obtained in pilot production runs with 4 ft2 tandem modules.

  14. Fully low voltage and large area searching scanning tunneling microscope

    International Nuclear Information System (INIS)

    Pang, Zongqiang; Wang, Jihui; Lu, Qingyou

    2009-01-01

    We present a novel scanning tunneling microscope (STM), which allows the tip to travel a large distance (millimeters) on the sample and take images (to find microscopic targets) anywhere it reaches without losing atomic resolution. This broad range searching capability, together with the coarse approach and scan motion, is all done with only one single piezoelectric tube scanner as well as with only low voltages (<15 V). Simple structure, low interference and high precision are thus achieved. To this end, a pillar and a tube scanner are mounted in parallel on a base with one ball glued on the pillar top and two balls glued on the scanner top. These three balls form a narrow triangle, which supports a triangular slider piece. By inertial stepping, the scanner can move the slider toward the pillar (coarse approach) or rotate the slider about the pillar (travel along sample surface). Since all the stepping motions are driven by the scanner's lateral bending which is large per unit voltage, high voltages are unnecessary. The technology is also applicable to scanning force microscopes (SFM) such as atomic force microscopes (AFM), etc

  15. 102(ℎ/2π)k Large Area Atom Interferometers

    International Nuclear Information System (INIS)

    Chiow, Sheng-wey; Kovachy, Tim; Chien, Hui-Chun; Kasevich, Mark A.

    2011-01-01

    We demonstrate atom interferometers utilizing a novel beam splitter based on sequential multiphoton Bragg diffractions. With this sequential Bragg large momentum transfer (SB-LMT) beam splitter, we achieve high contrast atom interferometers with momentum splittings of up to 102 photon recoil momenta (102(ℎ/2π)k). To our knowledge, this is the highest momentum splitting achieved in any atom interferometer, advancing the state-of-the-art by an order of magnitude. We also demonstrate strong noise correlation between two simultaneous SB-LMT interferometers, which alleviates the need for ultralow noise lasers and ultrastable inertial environments in some future applications. Our method is intrinsically scalable and can be used to dramatically increase the sensitivity of atom interferometers in a wide range of applications, including inertial sensing, measuring the fine structure constant, and detecting gravitational waves.

  16. Large area spark counters with fine time and position resolution

    International Nuclear Information System (INIS)

    Ogawa, A.; Atwood, W.B.; Fujiwara, N.; Pestov, Yu.N.; Sugahara, R.

    1983-10-01

    Spark counters trace their history back over three decades but have been used in only a limited number of experiments. The key properties of these devices include their capability of precision timing (at the sub 100 ps level) and of measuring the position of the charged particle to high accuracy. At SLAC we have undertaken a program to develop these devices for use in high energy physics experiments involving large detectors. A spark counter of size 1.2 m x 0.1 m has been constructed and has been operating continuously in our test setup for several months. In this talk I will discuss some details of its construction and its properties as a particle detector. 14 references

  17. LSSA large area silicon sheet task continuous Czochralski process development

    Science.gov (United States)

    Rea, S. N.

    1978-01-01

    A Czochralski crystal growing furnace was converted to a continuous growth facility by installation of a premelter to provide molten silicon flow into the primary crucible. The basic furnace is operational and several trial crystals were grown in the batch mode. Numerous premelter configurations were tested both in laboratory-scale equipment as well as in the actual furnace. The best arrangement tested to date is a vertical, cylindrical graphite heater containing small fused silicon test tube liner in which the incoming silicon is melted and flows into the primary crucible. Economic modeling of the continuous Czochralski process indicates that for 10 cm diameter crystal, 100 kg furnace runs of four or five crystals each are near-optimal. Costs tend to asymptote at the 100 kg level so little additional cost improvement occurs at larger runs. For these conditions, crystal cost in equivalent wafer area of around $20/sq m exclusive of polysilicon and slicing was obtained.

  18. Electron Emission from Ultra-Large Area MOS Electron Emitters

    DEFF Research Database (Denmark)

    Thomsen, Lasse Bjørchmar; Nielsen, Gunver; Vendelbo, Søren Bastholm

    2009-01-01

    Ultralarge metal-oxide-semiconductor (MOS) devices with an active oxide area of 1 cm2 have been fabricated for use as electron emitters. The MOS structures consist of a Si substrate, a SiO2 tunnel barrier (~5 nm), a Ti wetting layer (3–10 Å), and a Au top layer (5–60 nm). Electron emission from...... layer is varied from 3 to 10 Å which changes the emission efficiency by more than one order of magnitude. The apparent mean free path of ~5 eV electrons in Au is found to be 52 Å. Deposition of Cs on the Au film increased the electron emission efficiency to 4.3% at 4 V by lowering the work function....... Electron emission under high pressures (up to 2 bars) of Ar was observed. ©2009 American Vacuum Society...

  19. Large-area sheet task advanced dendritic web growth development

    Science.gov (United States)

    Duncan, C. S.; Seidensticker, R. G.; Mchugh, J. P.

    1984-01-01

    The thermal models used for analyzing dendritic web growth and calculating the thermal stress were reexamined to establish the validity limits imposed by the assumptions of the models. Also, the effects of thermal conduction through the gas phase were evaluated and found to be small. New growth designs, both static and dynamic, were generated using the modeling results. Residual stress effects in dendritic web were examined. In the laboratory, new techniques for the control of temperature distributions in three dimensions were developed. A new maximum undeformed web width of 5.8 cm was achieved. A 58% increase in growth velocity of 150 micrometers thickness was achieved with dynamic hardware. The area throughput goals for transient growth of 30 and 35 sq cm/min were exceeded.

  20. Research status of large mode area single polarization active fiber

    Science.gov (United States)

    Xiao, Chun; Zhang, Ge; Yang, Bin-hua; Cheng, Wei-feng; Gu, Shao-yi

    2018-03-01

    As high power fiber laser used more and more widely, to increase the output power of fiber laser and beam quality improvement have become an important goal for the development of high power fiber lasers. The use of large mode fiber is the most direct and effective way to solve the nonlinear effect and fiber damage in the fiber laser power lifting process. In order to reduce the effect of polarization of the fiber laser system, the study found that when introduces a birefringence in the single-mode fiber, the polarization state changes caused by the birefringence is far greater than the random polarization state changes, then the external disturbance is completely submerged, finally the polarization can be controlled and stabilized. Through the fine design of the fiber structure, if the birefringence is high enough to achieve the separation of the two polarization states, the fiber will have a different cut-off mechanism to eliminate polarization which is not need, which will realize single mode single polarization transmission in a band. In this paper, different types of single polarization fiber design are presented and the application of these fibers are also discussed.

  1. A large-area RF source for negative hydrogen ions

    International Nuclear Information System (INIS)

    Frank, P.; Feist, J. H.; Kraus, W.; Speth, E.; Heinemann, B.; Probst, F.; Trainham, R.; Jacquot, C.

    1998-01-01

    In a collaboration with CEA Cadarache, IPP is presently developing an rf source, in which the production of negative ions (H - /D - ) is being investigated. It utilizes PINI-size rf sources with an external antenna and for the first step a small size extraction system with 48 cm 2 net extraction area. First results from BATMAN (Bavarian T lowbar est Machine for N lowbar egative Ions) show (without Cs) a linear dependence of the negative ion yield with rf power, without any sign of saturation. At elevated pressure (1.6 Pa) a current density of 4.5 mA/cm 2 H - (without Cs) has been found so far. At medium pressure (0.6 Pa) the current density is lower by approx. a factor of 5, but preliminary results with Cesium injection show a relative increase by almost the same factor in this pressure range. Langmuir probe measurements indicate an electron temperature T e >2 eV close to the plasma grid with a moderate magnetic filter (700 Gcm). Attempts to improve the performance by using different magnetic configurations and different wall materials are under way

  2. Readout for a large area neutron sensitive microchannel plate detector

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yiming [Department of Engineering Physics, Tsinghua University, Beijing (China); Key Laboratory of Particle & Radiation Imaging, Tsinghua University, Ministry of Education, Beijing (China); Yang, Yigang, E-mail: yangyigang@mail.tsinghua.edu.cn [Department of Engineering Physics, Tsinghua University, Beijing (China); Key Laboratory of Particle & Radiation Imaging, Tsinghua University, Ministry of Education, Beijing (China); Wang, Xuewu; Li, Yuanjing [Department of Engineering Physics, Tsinghua University, Beijing (China); Key Laboratory of Particle & Radiation Imaging, Tsinghua University, Ministry of Education, Beijing (China)

    2015-06-01

    A neutron sensitive microchannel plate (MCP) detector was developed for neutron imaging on the beamline of a compact pulsed hadron source (CPHS). The detector was set up with a Wedge-and-Strip Anode (WSA) and a delay line anode readout to compare the spatial resolution and throughput with these two anodes. Tests show that the WSA readout is suitable for small area imaging with a spatial resolution of 200 μm with low energy X-rays in a 50 mm diameter MCP–WSA assembly. However, the spatial resolution deteriorated to ~2 mm in a 106 mm diameter MCP–WSA assembly because the noise caused by the parasitic capacitance is 10 times larger in the larger assembly than in the 50 mm diameter assembly. A 120 mm by 120 mm delay line anode was then used for the 106 mm MCP readout. The spatial resolution was evaluated for various voltages applied to the MCP V-stack, various readout voltages and various distances between the MCP V-stack rear face and the delay line. The delay line readout had resolutions of 65.6 μm in the x direction and 63.7 μm in the y direction and the throughput was greater than 600 kcps. The MCP was then used to acquire a neutron image of an USAF1951 Gd-mask.

  3. A large area Micromegas TPC for tracking at the ILC

    International Nuclear Information System (INIS)

    Wang, Wenxin

    2013-01-01

    The study of the fundamental building blocks of matter necessitates always more powerful accelerators. New particles are produced in high energy collisions of protons or electrons. The by-Products of these collisions are detected in large apparatus surrounding the interaction point. The 125 GeV Higgs particle discovered at LHC will be studied in detail in the next e + e - collider. The leading project for this is called ILC. The team that I joined is working on the R and D for a Time Projection Chamber (TPC) to detect the charged tracks by the ionization they leave in a gas volume, optimised for use at ILC. This primary ionization is amplified by the so-Called Micromegas device, with a charge-Sharing anode made of a resistive-Capacitive coating. After a presentation of the physics motivation for the ILC and ILD detector, I will review the principle of operation of a TPC (Chapter 2) and underline the advantages of the Micromegas readout with charge sharing. The main part of this PhD work concerns the detailed study of up to 12 prototypes of various kinds. The modules and their readout electronics are described in Chapter 3. A test-Bench setup has been assembled at CERN (Chapter 4) to study the response to a 55 Fe source, allowing an energy calibration and a uniformity study. In Chapter 5, the ion back-flow is studied using a bulk Micromegas and the gas gain is measured using a calibrated electronics chain. With the same setup, the electron transparency is measured as a function of the field ratio (drift/amplification). Also, several beam tests have been carried out at DESY with a 5 GeV electron beam in a 1 T superconducting magnet. These beam tests allowed the detailed study of the spatial resolution. In the final test, the endplate was equipped with seven modules, bringing sensitivity to misalignment and distortions. Such a study required software developments (Chapter 6) to make optimal use of the charge sharing and to reconstruct multiple tracks through several

  4. Prospecting direction and favourable target areas for exploration of large and super-large uranium deposits in China

    International Nuclear Information System (INIS)

    Liu Xingzhong

    1993-01-01

    A host of large uranium deposits have been successively discovered abroad by means of geological exploration, metallogenetic model studies and the application of new geophysical and geochemical methods since 1970's. Thorough undertaking geological research relevant to prospecting for super large uranium deposits have attracted great attention of the worldwide geological circle. The important task for the vast numbers of uranium geological workers is to make an afford to discover more numerous large and super large uranium deposits in China. The author comprehensively analyses the regional geological setting and geological metallogenetic conditions for the super large uranium deposits in the world. Comparative studies have been undertaken and the prospecting direction and favourable target areas for the exploration of super large uranium deposits in China have been proposed

  5. Development of a Methodology for Predicting Forest Area for Large-Area Resource Monitoring

    Science.gov (United States)

    William H. Cooke

    2001-01-01

    The U.S. Department of Agriculture, Forest Service, Southcm Research Station, appointed a remote-sensing team to develop an image-processing methodology for mapping forest lands over large geographic areds. The team has presented a repeatable methodology, which is based on regression modeling of Advanced Very High Resolution Radiometer (AVHRR) and Landsat Thematic...

  6. Development of a photogrammetry technique for large-area deformation monitoring in coal mining areas

    International Nuclear Information System (INIS)

    Redweik, P.M.

    1993-01-01

    The investigations of ground movements in coal mining areas during the past 10 years have been performed by methods of aerial photogrammetry. The ground points used for the determination of the movement in urban areas are manhole covers. The measurements must be repeated every three or four years. These facts have motivated the development of a new automatic method for measuring photo coordinates. This method is implemented on the Rollei RS1 (Reseau-Scanner Monocomparator. The approximate photo coordinates that are needed for this instrument can be computed from the old ground coordinates of each point. The manhole cover will be first recognised with a sort of template matching. Its central point will then be computed by using an ellipse operator. (orig.) [de

  7. Hybrid Ytterbium-doped large-mode-area photonic crystal fiber amplifier for long wavelengths

    DEFF Research Database (Denmark)

    Petersen, Sidsel Rübner; Alkeskjold, Thomas T.; Poli, Federica

    2012-01-01

    A large-mode-area Ytterbium-doped photonic crystal fiber amplifier with build-in gain shaping is presented. The fiber cladding consists of a hexagonal lattice of air holes, where three rows are replaced with circular high-index inclusions. Seven missing air holes define the large-mode-area core. ...

  8. Effects of uncertainty in model predictions of individual tree volume on large area volume estimates

    Science.gov (United States)

    Ronald E. McRoberts; James A. Westfall

    2014-01-01

    Forest inventory estimates of tree volume for large areas are typically calculated by adding model predictions of volumes for individual trees. However, the uncertainty in the model predictions is generally ignored with the result that the precision of the large area volume estimates is overestimated. The primary study objective was to estimate the effects of model...

  9. Highly Flexible and High-Performance Complementary Inverters of Large-Area Transition Metal Dichalcogenide Monolayers

    KAUST Repository

    Pu, Jiang

    2016-03-23

    Complementary inverters constructed from large-area monolayers of WSe2 and MoS2 achieve excellent logic swings and yield an extremely high gain, large total noise margin, low power consumption, and good switching speed. Moreover, the WSe2 complementary-like inverters built on plastic substrates exhibit high mechanical stability. The results provide a path toward large-area flexible electronics. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. The Feasibility of Small Hydro-Electric Generation in a Large Urban Area

    OpenAIRE

    Benson Y. Zhang; Adam Taylor

    2012-01-01

    The possibilities of generating electric power from relatively small hydro-electric sources in a large urban area is investigated. Two different aspects of hydro-electric sources have been studied: storm/waste water pipes in large multi-tenanted residential buildings and urban storm water discharge area (CSI area). The potential to generate from these sources has been investigated using a micro-turbine. The potential electric power which could be extracted from the sources was estimated using...

  11. Site survey for large wind turbines in the Rijnmond area. Plaatsingsmogelijkheden grote windturbines in het Rijnmondgebied

    Energy Technology Data Exchange (ETDEWEB)

    Arkesteyn, L A; Van der Ham, P

    1985-01-01

    This paper reveals only preliminary results of a study on site selection for large wind turbines in a heavily industrialized and urbanized area of The Netherlands: the Rijnmond area. Factors like average wind speed, coupling to electric power grid, acquisition of land, noise pollution, safety aspects, avoiding harm to birds, and fitting in the existent physical structure of the area are evaluated.

  12. Posterior cerebellar Purkinje cells in an SCA5/SPARCA1 mouse model are especially vulnerable to the synergistic effect of loss of β-III spectrin and GLAST.

    Science.gov (United States)

    Perkins, Emma M; Suminaite, Daumante; Clarkson, Yvonne L; Lee, Sin Kwan; Lyndon, Alastair R; Rothstein, Jeffrey D; Wyllie, David J A; Tanaka, Kohichi; Jackson, Mandy

    2016-10-15

    Clinical phenotypes of spinocerebellar ataxia type-5 (SCA5) and spectrin-associated autosomal recessive cerebellar ataxia type-1 (SPARCA1) are mirrored in mice lacking β-III spectrin (β-III-/-). One function of β-III spectrin is the stabilization of the Purkinje cell-specific glutamate transporter EAAT4 at the plasma membrane. In β-III-/- mice EAAT4 levels are reduced from an early age. In contrast levels of the predominant cerebellar glutamate transporter GLAST, expressed in Bergmann glia, only fall progressively from 3 months onwards. Here we elucidated the roles of these two glutamate transporters in cerebellar pathogenesis mediated through loss of β-III spectrin function by studying EAAT4 and GLAST knockout mice as well as crosses of both with β-III-/- mice. Our data demonstrate that EAAT4 loss, but not abnormal AMPA receptor composition, in young β-III-/- mice underlies early Purkinje cell hyper-excitability and that subsequent loss of GLAST, superimposed on the earlier deficiency of EAAT4, is responsible for Purkinje cell loss and progression of motor deficits. Yet the loss of GLAST appears to be independent of EAAT4 loss, highlighting that other aspects of Purkinje cell dysfunction underpin the pathogenic loss of GLAST. Finally, our results demonstrate that Purkinje cells in the posterior cerebellum of β-III-/- mice are most susceptible to the combined loss of EAAT4 and GLAST, with degeneration of proximal dendrites, the site of climbing fibre innervation, most pronounced. This highlights the necessity for efficient glutamate clearance from these regions and identifies dysregulation of glutamatergic neurotransmission particularly within the posterior cerebellum as a key mechanism in SCA5 and SPARCA1 pathogenesis.

  13. Large area substrate for surface enhanced Raman spectroscopy (SERS) using glass-drawing technique

    Science.gov (United States)

    Ivanov, Ilia N; Simpson, John T

    2012-06-26

    A method of making a large area substrate comprises drawing a plurality of tubes to form a plurality of drawn tubes, and cutting the plurality of drawn tubes into cut drawn tubes. Each cut drawn tube has a first end and a second end along the longitudinal direction of the respective cut drawn tube. The cut drawn tubes collectively have a predetermined periodicity. The method of making a large area substrate also comprises forming a metal layer on the first ends of the cut drawn tubes to provide a large area substrate.

  14. Production of the Large-area Plastic Scintillator for Beta-ray Detection using Epoxy Resin

    International Nuclear Information System (INIS)

    Nam, Jong Soo; Choi, Yong Seok; Hong, Sang Bum; Seo, Bum Kyung; Moon, Jei Kwon; Choi, Jong Won

    2016-01-01

    In this study, we prepared a plastic scintillator whose manufacturing process is simple and can be freely shaped. A thin plate of the plastic scintillator was manufactured using epoxy resin as a polymer. The plastic scintillator was made by mixing epoxy resin and organic scintillators under various conditions. The optimal mixture ratio to prepare the plastic scintillator was derived from the above results. Using the derived results, we made the large-area plastic scintillator which can quickly measure the contamination site and evaluated characteristics of the large-area plastic scintillator in the laboratory. A thin plate of a plastic scintillator with a simple preparation process can be freely shaped using epoxy resin and organic scintillators such as PPO and POPOP. PPO emits scintillation of light in the ultraviolet range, and POPOP is a wave shifter for moving the wavelength responsible for the PMT. The mixture ratio of PPO and POPOP was determined using their emission spectra. The optimal weight percentage of PPO and POPOP in an organic scintillator was determined to be 0.2 wt%:0.01 wt%. Based on the above results, the large-area plastic scintillator of the window size of a typical pancake-type αβ surface contamination counter was prepared. We want to evaluate the characteristics of the large-area plastic scintillator. However, there were the difficulties in evaluating characteristics of the large-area plastic scintillator. The cross-sectional area of the large-area plastic scintillator is significantly different to PMT

  15. Production of the Large-area Plastic Scintillator for Beta-ray Detection using Epoxy Resin

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Jong Soo; Choi, Yong Seok; Hong, Sang Bum; Seo, Bum Kyung; Moon, Jei Kwon; Choi, Jong Won [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    In this study, we prepared a plastic scintillator whose manufacturing process is simple and can be freely shaped. A thin plate of the plastic scintillator was manufactured using epoxy resin as a polymer. The plastic scintillator was made by mixing epoxy resin and organic scintillators under various conditions. The optimal mixture ratio to prepare the plastic scintillator was derived from the above results. Using the derived results, we made the large-area plastic scintillator which can quickly measure the contamination site and evaluated characteristics of the large-area plastic scintillator in the laboratory. A thin plate of a plastic scintillator with a simple preparation process can be freely shaped using epoxy resin and organic scintillators such as PPO and POPOP. PPO emits scintillation of light in the ultraviolet range, and POPOP is a wave shifter for moving the wavelength responsible for the PMT. The mixture ratio of PPO and POPOP was determined using their emission spectra. The optimal weight percentage of PPO and POPOP in an organic scintillator was determined to be 0.2 wt%:0.01 wt%. Based on the above results, the large-area plastic scintillator of the window size of a typical pancake-type αβ surface contamination counter was prepared. We want to evaluate the characteristics of the large-area plastic scintillator. However, there were the difficulties in evaluating characteristics of the large-area plastic scintillator. The cross-sectional area of the large-area plastic scintillator is significantly different to PMT.

  16. EnviroAtlas - Percent Large, Medium, and Small Natural Areas for the Conterminous United States

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset contains the percentage of small, medium, and large natural areas for each Watershed Boundary Dataset (WBD) 12-Digit Hydrologic Unit Code...

  17. Large Area Diamond Tribological Surfaces with Negligible Wear in Extreme Environments, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — In Phase I we propose to demonstrate the processing of very large area diamond sliding bearings and tribological surfaces. The bearings and surfaces will experience...

  18. 3D-Printed Disposable Wireless Sensors with Integrated Microelectronics for Large Area Environmental Monitoring

    KAUST Repository

    Farooqui, Muhammad Fahad; Karimi, Muhammad Akram; Salama, Khaled N.; Shamim, Atif

    2017-01-01

    disposable, compact, dispersible 3D-printed wireless sensor nodes with integrated microelectronics which can be dispersed in the environment and work in conjunction with few fixed nodes for large area monitoring applications. As a proof of concept

  19. Characterisation of large area THGEMs and experimental measurement of the Townsend coefficients for CF4

    Science.gov (United States)

    Burns, J.; Crane, T.; Ezeribe, A. C.; Grove, C. L.; Lynch, W.; Scarff, A.; Spooner, N. J. C.; Steer, C.

    2017-10-01

    Whilst the performance of small THGEMs is well known, here we consider the challenges in scaling these up to large area charge readouts. We first verify the expected gain of larger THGEMs by reporting experimental Townsend coefficients for a 10 cm diameter THGEM in low-pressure CF4. Large area 50 cm by 50 cm THGEMs were sourced from a commercial PCB supplier and geometrical imperfections were observed which we quantified using an optical camera setup. The large area THGEMs were experimentally characterised at Boulby Underground Laboratory through a series of gain calibrations and alpha spectrum measurements. ANSYS, Magboltz and Garfield++ simulations of the design of a TPC based on the large area THGEMs are presented. We also consider their implications for directional dark matter research and potential applications within nuclear security.

  20. Low-Power Large-Area Radiation Detector for Space Science Measurements

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this task is to develop a low-power, large-area detectors from SiC, taking advantage of very low thermal noise characteristics and high radiation...

  1. Pure crystal orientation and anisotropic charge transport in large-area hybrid perovskite films

    KAUST Repository

    Cho, Nam Chul; Li, Feng; Turedi, Bekir; Sinatra, Lutfan; Sarmah, Smritakshi P.; Parida, Manas R.; Saidaminov, Makhsud I.; Banavoth, Murali; Burlakov, Victor M.; Goriely, Alain; Mohammed, Omar F.; Wu, Tao; Bakr, Osman

    2016-01-01

    Controlling crystal orientations and macroscopic morphology is vital to develop the electronic properties of hybrid perovskites. Here we show that a large-area, orientationally pure crystalline (OPC) methylammonium lead iodide (MAPbI3) hybrid

  2. Solution coating of large-area organic semiconductor thin films with aligned single-crystalline domains

    KAUST Repository

    Diao, Ying; Tee, Benjamin C-K.; Giri, Gaurav; Xu, Jie; Kim, Do Hwan; Becerril, Hector A.; Stoltenberg, Randall M.; Lee, Tae Hoon; Xue, Gi; Mannsfeld, Stefan C. B.; Bao, Zhenan

    2013-01-01

    Solution coating of organic semiconductors offers great potential for achieving low-cost manufacturing of large-area and flexible electronics. However, the rapid coating speed needed for industrial-scale production poses challenges to the control

  3. 55-68 Impact of Area Enclosures on Density and Diversity of Large ...

    African Journals Online (AJOL)

    1Department of Land Resources Management and Environmental Protection, Mekelle University, ... The enclosures have higher density and diversity of large wild mammals ..... in it. Figure 4 Human interference in enclosures of the study area ...

  4. Frequency conversion through spontaneous degenerate four wave mixing in large mode area hybrid photonic crystal fibers

    DEFF Research Database (Denmark)

    Petersen, Sidsel Rübner; Alkeskjold, Thomas Tanggaard; Olausson, Christina Bjarnal Thulin

    2014-01-01

    Frequency conversion through spontaneous degenerate four wave mixing (FWM) is investigated in large mode area hybrid photonic crystal fibers. Different FWM processes are observed, phasematching between fiber modes of orthogonal polarization, intermodal phasematching across bandgaps, and intramodal...

  5. Intermodal parametric gain of degenerate four wave mixing in large mode area hybrid photonic crystal fibers

    DEFF Research Database (Denmark)

    Petersen, Sidsel Rübner; Lægsgaard, Jesper; Alkeskjold, Thomas Tanggaard

    2013-01-01

    Intermodal degenerate four wave mixing (FWM) is investigated numerically in large mode area hybrid photonic crystal fibers. The dispersion is controlled independently of core size, and thus allows for power scaling of the FWM process.......Intermodal degenerate four wave mixing (FWM) is investigated numerically in large mode area hybrid photonic crystal fibers. The dispersion is controlled independently of core size, and thus allows for power scaling of the FWM process....

  6. Detecting Change in Landscape Greenness over Large Areas: An Example for New Mexico, USA

    Science.gov (United States)

    Monitoring and quantifying changes in vegetation cover over large areas using remote sensing can potentially detect large-scale, slow changes (e.g., climate change), as well as more local and rapid changes (e.g., fire, land development). A useful indicator for detecting change i...

  7. Period doubling and chaos in large area Josephson junctions induced by rf signals

    DEFF Research Database (Denmark)

    Olsen, O. H.; Samuelsen, Mogens Rugholm

    1985-01-01

    The influence of an applied rf signal on the emitted radiation from a large area Josephson junction is examined. A model of the system is presented in the framework of the one-dimensional sine-Gordon equation. The model linearizes for small and large values of the amplitude of the applied signal...

  8. Highly Flexible and High-Performance Complementary Inverters of Large-Area Transition Metal Dichalcogenide Monolayers

    KAUST Repository

    Pu, Jiang; Funahashi, Kazuma; Chen, Chang-Hsiao; Li, Ming-yang; Li, Lain-Jong; Takenobu, Taishi

    2016-01-01

    Complementary inverters constructed from large-area monolayers of WSe2 and MoS2 achieve excellent logic swings and yield an extremely high gain, large total noise margin, low power consumption, and good switching speed. Moreover, the WSe2

  9. COMPARISON OF MULTI-SCALE DIGITAL ELEVATION MODELS FOR DEFINING WATERWAYS AND CATCHMENTS OVER LARGE AREAS

    Directory of Open Access Journals (Sweden)

    B. Harris

    2012-07-01

    Full Text Available Digital Elevation Models (DEMs allow for the efficient and consistent creation of waterways and catchment boundaries over large areas. Studies of waterway delineation from DEMs are usually undertaken over small or single catchment areas due to the nature of the problems being investigated. Improvements in Geographic Information Systems (GIS techniques, software, hardware and data allow for analysis of larger data sets and also facilitate a consistent tool for the creation and analysis of waterways over extensive areas. However, rarely are they developed over large regional areas because of the lack of available raw data sets and the amount of work required to create the underlying DEMs. This paper examines definition of waterways and catchments over an area of approximately 25,000 km2 to establish the optimal DEM scale required for waterway delineation over large regional projects. The comparative study analysed multi-scale DEMs over two test areas (Wivenhoe catchment, 543 km2 and a detailed 13 km2 within the Wivenhoe catchment including various data types, scales, quality, and variable catchment input parameters. Historic and available DEM data was compared to high resolution Lidar based DEMs to assess variations in the formation of stream networks. The results identified that, particularly in areas of high elevation change, DEMs at 20 m cell size created from broad scale 1:25,000 data (combined with more detailed data or manual delineation in flat areas are adequate for the creation of waterways and catchments at a regional scale.

  10. Comparison of Multi-Scale Digital Elevation Models for Defining Waterways and Catchments Over Large Areas

    Science.gov (United States)

    Harris, B.; McDougall, K.; Barry, M.

    2012-07-01

    Digital Elevation Models (DEMs) allow for the efficient and consistent creation of waterways and catchment boundaries over large areas. Studies of waterway delineation from DEMs are usually undertaken over small or single catchment areas due to the nature of the problems being investigated. Improvements in Geographic Information Systems (GIS) techniques, software, hardware and data allow for analysis of larger data sets and also facilitate a consistent tool for the creation and analysis of waterways over extensive areas. However, rarely are they developed over large regional areas because of the lack of available raw data sets and the amount of work required to create the underlying DEMs. This paper examines definition of waterways and catchments over an area of approximately 25,000 km2 to establish the optimal DEM scale required for waterway delineation over large regional projects. The comparative study analysed multi-scale DEMs over two test areas (Wivenhoe catchment, 543 km2 and a detailed 13 km2 within the Wivenhoe catchment) including various data types, scales, quality, and variable catchment input parameters. Historic and available DEM data was compared to high resolution Lidar based DEMs to assess variations in the formation of stream networks. The results identified that, particularly in areas of high elevation change, DEMs at 20 m cell size created from broad scale 1:25,000 data (combined with more detailed data or manual delineation in flat areas) are adequate for the creation of waterways and catchments at a regional scale.

  11. Productivity and efficiency of economic activity of the Lower Silesia's large area farms in comparison with other large area farms in Poland

    Directory of Open Access Journals (Sweden)

    Stanisław Minta

    2009-01-01

    Full Text Available The paper shows economical and financial situation of the agricultural companies which have most of the grounds in lease. Analysed objects were settled on Lower Silesia (the province in the south – west Poland. The main part of the results of research was about productivity and efficiency of economic resources in these objects. The research was made in years 2000-2002. The results of research in analyzed Lower Silesia’s companies were compared with the best Polish large area farms in order of law and organisation forms: leased farms, private farms and partnerships of Polish public agency AWRSP.

  12. A facile alternative technique for large-area graphene transfer via sacrificial polymer

    Directory of Open Access Journals (Sweden)

    Eric Auchter

    2017-12-01

    Full Text Available A novel method of transferring large-area graphene sheets onto a variety of substrates using Formvar (polyvinyl formal is presented. Due to the ease at which formvar can be dissolved in chloroform this method allows for a consistent, a clean, and a more rapid transfer than other techniques including the PMMA assisted one. This novel transfer method is demonstrated by transferring large-area graphene onto a range of substrates including commercial TEM grids, silicon dioxide and glass. Raman spectroscopy was used to confirm the presence of graphene and characterize the morphological properties of the large-area sheets. SEM and AFM analyses demonstrated the effectiveness of our rapid transfer technique for clean crystalline large-area graphene sheets. The removal of the sacrificial polymer was found to be one to two orders of magnitude faster than PMMA methods. Ultimately this facile transfer technique offers new opportunities for a wide range of applications for large-area graphene through the utilization of a new sacrificial polymer.

  13. Design of a broadband ultra-large area acoustic cloak based on a fluid medium

    Science.gov (United States)

    Zhu, Jian; Chen, Tianning; Liang, Qingxuan; Wang, Xiaopeng; Jiang, Ping

    2014-10-01

    A broadband ultra-large area acoustic cloak based on fluid medium was designed and numerically implemented with homogeneous metamaterials according to the transformation acoustics. In the present work, fluid medium as the body of the inclusion could be tuned by changing the fluid to satisfy the variant acoustic parameters instead of redesign the whole cloak. The effective density and bulk modulus of the composite materials were designed to agree with the parameters calculated from the coordinate transformation methodology by using the effective medium theory. Numerical simulation results showed that the sound propagation and scattering signature could be controlled in the broadband ultra-large area acoustic invisibility cloak, and good cloaking performance has been achieved and physically realized with homogeneous materials. The broadband ultra-large area acoustic cloaking properties have demonstrated great potentials in the promotion of the practical applications of acoustic cloak.

  14. Solution Coating of Superior Large-Area Flexible Perovskite Thin Films with Controlled Crystal Packing

    KAUST Repository

    Li, Jianbo

    2017-05-08

    Solution coating of organohalide lead perovskites offers great potential for achieving low-cost manufacturing of large-area flexible optoelectronics. However, the rapid coating speed needed for industrial-scale production poses challenges to the control of crystal packing. Herein, this study reports using solution shearing to confine crystal nucleation and growth in large-area printed MAPbI3 thin films. Near single-crystalline perovskite microarrays are demonstrated with a high degree of controlled macroscopic alignment and crystal orientation, which exhibit significant improvements in optical and optoelectronic properties comparing with their random counterparts, spherulitic, and nanograined films. In particular, photodetectors based on the confined films showing intense anisotropy in charge transport are fabricated, and the device exhibits significantly improved performance in all aspects by one more orders of magnitude relative to their random counterparts. It is anticipated that perovskite films with controlled crystal packing may find applications in high-performance, large-area printed optoelectronics, and solar cells.

  15. Chemical hole doping into large-area transition metal dichalcogenide monolayers using boron-based oxidant

    KAUST Repository

    Matsuoka, Hirofumi; Kanahashi, Kaito; Tanaka, Naoki; Shoji, Yoshiaki; Li, Lain-Jong; Pu, Jiang; Ito, Hiroshi; Ohta, Hiromichi; Fukushima, Takanori; Takenobu, Taishi

    2018-01-01

    Hole carrier doping into single-crystalline transition metal dichalcogenide (TMDC) films can be achieved with various chemical reagents. However, large-area polycrystalline TMDC monolayers produced by a chemical vapor deposition (CVD) growth method have yet to be chemically doped. Here, we report that a salt of a two-coordinate boron cation, Mes2B+ (Mes: 2,4,6-trimethylphenyl group), with a chemically stable tetrakis(pentafluorophenyl)borate anion, [(C6F5)4B]−, can serve as an efficient hole-doping reagent for large-area CVD-grown tungsten diselenide (WSe2) films. Upon doping, the sheet resistance of large-area polycrystalline WSe2 monolayers decreased from 90 GΩ/sq to 3.2 kΩ/sq.

  16. Programmable and functional electrothermal bimorph actuators based on large-area anisotropic carbon nanotube paper

    Science.gov (United States)

    Li, Qingwei; Liu, Changhong; Fan, Shoushan

    2018-04-01

    Electro-active polymer (EAP) actuators, such as electronic, ionic and electrothermal (ET) actuators, have become an important branch of next-generation soft actuators in bionic robotics. However, most reported EAP actuators could realize only simple movements, being restricted by the small area of flexible electrodes and simple designs. We prepared large-area flexible electrodes of high anisotropy, made of oriented carbon nanotube (CNT) paper, and carried out artful graphic designs and processing on the electrodes to make functional ET bimorph actuators which can realize large bending deformations (over 220°, curvature > 1.5 cm-1) and bionic movements driven by electricity. The anisotropy of CNT paper benefits electrode designs and multiform actuations for complex actuators. Based on the large-area CNT paper, more interesting and functional actuators can be designed and prepared which will have practical applications in the fields of artificial muscles, complicated actuations, and soft and bionic robotics.

  17. Chemical hole doping into large-area transition metal dichalcogenide monolayers using boron-based oxidant

    KAUST Repository

    Matsuoka, Hirofumi

    2018-01-18

    Hole carrier doping into single-crystalline transition metal dichalcogenide (TMDC) films can be achieved with various chemical reagents. However, large-area polycrystalline TMDC monolayers produced by a chemical vapor deposition (CVD) growth method have yet to be chemically doped. Here, we report that a salt of a two-coordinate boron cation, Mes2B+ (Mes: 2,4,6-trimethylphenyl group), with a chemically stable tetrakis(pentafluorophenyl)borate anion, [(C6F5)4B]−, can serve as an efficient hole-doping reagent for large-area CVD-grown tungsten diselenide (WSe2) films. Upon doping, the sheet resistance of large-area polycrystalline WSe2 monolayers decreased from 90 GΩ/sq to 3.2 kΩ/sq.

  18. 3D-Printed Disposable Wireless Sensors with Integrated Microelectronics for Large Area Environmental Monitoring

    KAUST Repository

    Farooqui, Muhammad Fahad

    2017-05-19

    Large area environmental monitoring can play a crucial role in dealing with crisis situations. However, it is challenging as implementing a fixed sensor network infrastructure over large remote area is economically unfeasible. This work proposes disposable, compact, dispersible 3D-printed wireless sensor nodes with integrated microelectronics which can be dispersed in the environment and work in conjunction with few fixed nodes for large area monitoring applications. As a proof of concept, the wireless sensing of temperature, humidity, and H2S levels are shown which are important for two critical environmental conditions namely forest fires and industrial leaks. These inkjet-printed sensors and an antenna are realized on the walls of a 3D-printed cubic package which encloses the microelectronics developed on a 3D-printed circuit board. Hence, 3D printing and inkjet printing are uniquely combined in order to realize a low-cost, fully integrated wireless sensor node.

  19. Solution Coating of Superior Large-Area Flexible Perovskite Thin Films with Controlled Crystal Packing

    KAUST Repository

    Li, Jianbo; Liu, Yucheng; Ren, Xiaodong; Yang, Zhou; Li, Ruipeng; Su, Hang; Yang, Xiaoming; Xu, Junzhuo; Xu, Hua; Hu, Jian-Yong; Amassian, Aram; Zhao, Kui; Liu, Shengzhong Frank

    2017-01-01

    Solution coating of organohalide lead perovskites offers great potential for achieving low-cost manufacturing of large-area flexible optoelectronics. However, the rapid coating speed needed for industrial-scale production poses challenges to the control of crystal packing. Herein, this study reports using solution shearing to confine crystal nucleation and growth in large-area printed MAPbI3 thin films. Near single-crystalline perovskite microarrays are demonstrated with a high degree of controlled macroscopic alignment and crystal orientation, which exhibit significant improvements in optical and optoelectronic properties comparing with their random counterparts, spherulitic, and nanograined films. In particular, photodetectors based on the confined films showing intense anisotropy in charge transport are fabricated, and the device exhibits significantly improved performance in all aspects by one more orders of magnitude relative to their random counterparts. It is anticipated that perovskite films with controlled crystal packing may find applications in high-performance, large-area printed optoelectronics, and solar cells.

  20. Voltage uniformity study in large-area reactors for RF plasma deposition

    Energy Technology Data Exchange (ETDEWEB)

    Sansonnens, L.; Pletzer, A.; Magni, D.; Howling, A.A.; Hollenstein, C. [Ecole Polytechnique Federale, Lausanne (Switzerland). Centre de Recherche en Physique des Plasma (CRPP); Schmitt, J.P.M. [Balzers Process Systems, Palaiseau (France)

    1996-09-01

    Non-uniform voltage distribution across the electrode area results in inhomogeneous thin-film RF plasma deposition in large area reactors. In this work, a two-dimensional analytic model for the calculation of the voltage distribution across the electrode area is presented. The results of this model are in good agreement with measurements performed without plasma at 13.56 MHz and 70 MHz in a large area reactor. The principal voltage inhomogeneities are caused by logarithmic singularities in the vicinity of RF connections and not by standing waves. These singularities are only described by a two-dimensional model and cannot be intuitively predicted by analogy to a one-dimensional case. Plasma light emission measurements and thickness homogeneity studies of a-Si:H films show that the plasma reproduces these voltage inhomogeneities. Improvement of the voltage uniformity is investigated by changing the number and position of the RF connections. (author) 13 figs., 20 refs.

  1. The use of large area silicon sensors for thermal neutron detection

    International Nuclear Information System (INIS)

    Schulte, R.L.; Swanson, F.; Kesselman, M.

    1994-01-01

    The use of large area planar silicon detectors coupled with gadolinium foils has been investigated to develop a thermal neutron detector having a large area-efficiency (Aε) product. Noise levels due to high detector capacitance limit the size of silicon detectors that can be utilized. Calculations using the Monte Carlo code, MCNP, have been made to determine the variation of intrinsic detection efficiency as a function of the discriminator threshold level required to eliminate the detector noise. Measurements of the noise levels for planar silicon detectors of various resistivities (400, 3000 and 5000 Ω cm) have been made and the optimal detector area-efficiency products have been determined. The response of a Si-Gd-Si sandwich detector with areas between 1 cm 2 and 10.5 cm 2 is presented and the effects of the detector capacitance and reverse current are discussed. ((orig.))

  2. The use of large area silicon sensors for thermal neutron detection

    Energy Technology Data Exchange (ETDEWEB)

    Schulte, R.L. (Research and Development Center, Mail Stop: A01-26, Grumman Aerospace Corporation, Bethpage, NY 11714 (United States)); Swanson, F. (Research and Development Center, Mail Stop: A01-26, Grumman Aerospace Corporation, Bethpage, NY 11714 (United States)); Kesselman, M. (Research and Development Center, Mail Stop: A01-26, Grumman Aerospace Corporation, Bethpage, NY 11714 (United States))

    1994-12-30

    The use of large area planar silicon detectors coupled with gadolinium foils has been investigated to develop a thermal neutron detector having a large area-efficiency (A[epsilon]) product. Noise levels due to high detector capacitance limit the size of silicon detectors that can be utilized. Calculations using the Monte Carlo code, MCNP, have been made to determine the variation of intrinsic detection efficiency as a function of the discriminator threshold level required to eliminate the detector noise. Measurements of the noise levels for planar silicon detectors of various resistivities (400, 3000 and 5000 [Omega] cm) have been made and the optimal detector area-efficiency products have been determined. The response of a Si-Gd-Si sandwich detector with areas between 1 cm[sup 2] and 10.5 cm[sup 2] is presented and the effects of the detector capacitance and reverse current are discussed. ((orig.))

  3. Clean-lifting transfer of large-area residual-free graphene films.

    Science.gov (United States)

    Wang, Di-Yan; Huang, I-Sheng; Ho, Po-Hsun; Li, Shao-Sian; Yeh, Yun-Chieh; Wang, Duan-Wei; Chen, Wei-Liang; Lee, Yu-Yang; Chang, Yu-Ming; Chen, Chia-Chun; Liang, Chi-Te; Chen, Chun-Wei

    2013-08-27

    A unique "clean-lifting transfer" (CLT) technique that applies a controllable electrostatic force to transfer large-area and high-quality CVD-grown graphene onto various rigid or flexible substrates is reported. The CLT technique without using any organic support or adhesives can produce residual-free graphene films with large-area processability, and has great potential for future industrial production of graphene-based electronics or optoelectronics. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Quantum efficiency measurement system for large area CsI photodetectors

    CERN Document Server

    Cusanno, F; Colilli, S; Crateri, R; Fratoni, R; Frullani, S; Garibaldi, F; Giuliani, F; Gricia, M; Lucentini, M; Mostarda, A; Santavenere, F; Veneroni, P; Breuer, H; Iodice, M; Urciuoli, G M; De Cataldo, G; De Leo, R; Lagamba, L; Braem, André

    2003-01-01

    A proximity focusing freon/CsI RICH detector has been built for kaon physics at Thomas Jefferson National Accelerator Facility (TJNAF or Jefferson Lab), Hall A. The Cherenkov photons are detected by a UV photosensitive CsI film which has been obtained by vacuum evaporation. A dedicated evaporation facility for large area photocathodes has been built for this task. A measuring system has been built to allow the evaluation of the absolute quantum efficiency (QE) just after the evaporation. The evaporation facility is described here, as well as the quantum efficiency measurement device. Results of the QE on-line measurements, for the first time on large area photocathodes, are reported.

  5. Fast mapping algorithm of lighting spectrum and GPS coordinates for a large area

    Science.gov (United States)

    Lin, Chih-Wei; Hsu, Ke-Fang; Hwang, Jung-Min

    2016-09-01

    In this study, we propose a fast rebuild technology for evaluating light quality in large areas. Outdoor light quality, which is measured by illuminance uniformity and the color rendering index, is difficult to conform after improvement. We develop an algorithm for a lighting quality mapping system and coordinates using a micro spectrometer and GPS tracker integrated with a quadcopter or unmanned aerial vehicle. After cruising at a constant altitude, lighting quality data is transmitted and immediately mapped to evaluate the light quality in a large area.

  6. Efficient Mid-Infrared Supercontinuum Generation in Tapered Large Mode Area Chalcogenide Photonic Crystal Fibers

    DEFF Research Database (Denmark)

    Petersen, Christian Rosenberg; Engelsholm, Rasmus Dybbro; Markos, Christos

    2017-01-01

    Mid-infrared supercontinuum spanning from 1.8-9  μm with an output power of 41.5 mW is demonstrated by pumping tapered large mode area chalcogenide photonic crystal fibers using a 4 μm optical parametric source.......Mid-infrared supercontinuum spanning from 1.8-9  μm with an output power of 41.5 mW is demonstrated by pumping tapered large mode area chalcogenide photonic crystal fibers using a 4 μm optical parametric source....

  7. A Brief Technical History of the Large-Area Picosecond Photodetector (LAPPD) Collaboration

    Energy Technology Data Exchange (ETDEWEB)

    Adams, B.W.; et al.

    2016-03-06

    The Large Area Picosecond PhotoDetector (LAPPD) Collaboration was formed in 2009 to develop large-area photodetectors capable of time resolutions measured in pico-seconds, with accompanying sub-millimeter spatial resolution. During the next three and one-half years the Collaboration developed the LAPPD design of 20 x 20 cm modules with gains greater than $10^7$ and non-uniformity less than $15\\%$, time resolution less than 50 psec for single photons and spatial resolution of 700~microns in both lateral dimensions. We describe the R\\&D performed to develop large-area micro-channel plate glass substrates, resistive and secondary-emitting coatings, large-area bialkali photocathodes, and RF-capable hermetic packaging. In addition, the Collaboration developed the necessary electronics for large systems capable of precise timing, built up from a custom low-power 15-GigaSample/sec waveform sampling 6-channel integrated circuit and supported by a two-level modular data acquisition system based on Field-Programmable Gate Arrays for local control, data-sparcification, and triggering. We discuss the formation, organization, and technical successes and short-comings of the Collaboration. The Collaboration ended in December 2012 with a transition from R\\&D to commercialization.

  8. Large area synchrotron X-ray fluorescence mapping of biological samples

    International Nuclear Information System (INIS)

    Kempson, I.; Thierry, B.; Smith, E.; Gao, M.; De Jonge, M.

    2014-01-01

    Large area mapping of inorganic material in biological samples has suffered severely from prohibitively long acquisition times. With the advent of new detector technology we can now generate statistically relevant information for studying cell populations, inter-variability and bioinorganic chemistry in large specimen. We have been implementing ultrafast synchrotron-based XRF mapping afforded by the MAIA detector for large area mapping of biological material. For example, a 2.5 million pixel map can be acquired in 3 hours, compared to a typical synchrotron XRF set-up needing over 1 month of uninterrupted beamtime. Of particular focus to us is the fate of metals and nanoparticles in cells, 3D tissue models and animal tissues. The large area scanning has for the first time provided statistically significant information on sufficiently large numbers of cells to provide data on intercellular variability in uptake of nanoparticles. Techniques such as flow cytometry generally require analysis of thousands of cells for statistically meaningful comparison, due to the large degree of variability. Large area XRF now gives comparable information in a quantifiable manner. Furthermore, we can now image localised deposition of nanoparticles in tissues that would be highly improbable to 'find' by typical XRF imaging. In addition, the ultra fast nature also makes it viable to conduct 3D XRF tomography over large dimensions. This technology avails new opportunities in biomonitoring and understanding metal and nanoparticle fate ex-vivo. Following from this is extension to molecular imaging through specific anti-body targeted nanoparticles to label specific tissues and monitor cellular process or biological consequence

  9. [100] or [110] aligned, semiconductor-based, large-area, flexible, electronic devices

    Science.gov (United States)

    Goyal, Amit

    2015-03-24

    Novel articles and methods to fabricate the same resulting in flexible, large-area, [100] or [110] textured, semiconductor-based, electronic devices are disclosed. Potential applications of resulting articles are in areas of photovoltaic devices, flat-panel displays, thermophotovoltaic devices, ferroelectric devices, light emitting diode devices, computer hard disc drive devices, magnetoresistance based devices, photoluminescence based devices, non-volatile memory devices, dielectric devices, thermoelectric devices and quantum dot laser devices.

  10. Canopy area of large trees explains aboveground biomass variations across neotropical forest landscapes

    Science.gov (United States)

    Meyer, Victoria; Saatchi, Sassan; Clark, David B.; Keller, Michael; Vincent, Grégoire; Ferraz, António; Espírito-Santo, Fernando; d'Oliveira, Marcus V. N.; Kaki, Dahlia; Chave, Jérôme

    2018-06-01

    Large tropical trees store significant amounts of carbon in woody components and their distribution plays an important role in forest carbon stocks and dynamics. Here, we explore the properties of a new lidar-derived index, the large tree canopy area (LCA) defined as the area occupied by canopy above a reference height. We hypothesize that this simple measure of forest structure representing the crown area of large canopy trees could consistently explain the landscape variations in forest volume and aboveground biomass (AGB) across a range of climate and edaphic conditions. To test this hypothesis, we assembled a unique dataset of high-resolution airborne light detection and ranging (lidar) and ground inventory data in nine undisturbed old-growth Neotropical forests, of which four had plots large enough (1 ha) to calibrate our model. We found that the LCA for trees greater than 27 m (˜ 25-30 m) in height and at least 100 m2 crown size in a unit area (1 ha), explains more than 75 % of total forest volume variations, irrespective of the forest biogeographic conditions. When weighted by average wood density of the stand, LCA can be used as an unbiased estimator of AGB across sites (R2 = 0.78, RMSE = 46.02 Mg ha-1, bias = -0.63 Mg ha-1). Unlike other lidar-derived metrics with complex nonlinear relations to biomass, the relationship between LCA and AGB is linear and remains unique across forest types. A comparison with tree inventories across the study sites indicates that LCA correlates best with the crown area (or basal area) of trees with diameter greater than 50 cm. The spatial invariance of the LCA-AGB relationship across the Neotropics suggests a remarkable regularity of forest structure across the landscape and a new technique for systematic monitoring of large trees for their contribution to AGB and changes associated with selective logging, tree mortality and other types of tropical forest disturbance and dynamics.

  11. A large-scale deforestation experiment: Effects of patch area and isolation on Amazon birds

    Science.gov (United States)

    Ferraz, G.; Nichols, J.D.; Hines, J.E.; Stouffer, P.C.; Bierregaard, R.O.; Lovejoy, T.E.

    2007-01-01

    As compared with extensive contiguous areas, small isolated habitat patches lack many species. Some species disappear after isolation; others are rarely found in any small patch, regardless of isolation. We used a 13-year data set of bird captures from a large landscape-manipulation experiment in a Brazilian Amazon forest to model the extinction-colonization dynamics of 55 species and tested basic predictions of island biogeography and metapopulation theory. From our models, we derived two metrics of species vulnerability to changes in isolation and patch area. We found a strong effect of area and a variable effect of isolation on the predicted patch occupancy by birds.

  12. The spatial thickness distribution of metal films produced by large area pulsed laser deposition

    DEFF Research Database (Denmark)

    Pryds, Nini; Schou, Jørgen; Linderoth, Søren

    2007-01-01

    Thin films of metals have been deposited in the large-area Pulsed Laser Deposition (PLD) Facility at Riso National Laboratory. Thin films of Ag and Ni were deposited with laser pulses from an excimer laser at 248 nm with a rectangular beam spot at a fluence of 10 J/cm(2) on glass substrates of 127...

  13. Single-grain Silicon Technology for Large Area X-ray Imaging

    NARCIS (Netherlands)

    Arslan, A.

    2015-01-01

    Digital flat panel X-ray imagers are currently using a-Si and poly-Si thin-film-transistors (TFTs). a-Si TFT permits the use of large area substrates, however, due to the amorphous nature, the carrier mobility is very low (<1 cm2/Vs). Poly-Si TFT improves the mobility (~150 cm2/Vs) but due to random

  14. Wide-area phase-contrast X-ray imaging using large X-ray interferometers

    Energy Technology Data Exchange (ETDEWEB)

    Momose, Atsushi E-mail: momose@exp.t.u-tokyo.ac.jp; Takeda, Tohoru; Yoneyama, Akio; Koyama, Ichiro; Itai, Yuji

    2001-07-21

    Large X-ray interferometers are developed for phase-contrast X-ray imaging aiming at medical applications. A monolithic X-ray interferometer and a separate one are studied, and currently a 25 mmx20 mm view area can be generated. This paper describes the strategy of our research program and some recent developments.

  15. Wide-area phase-contrast X-ray imaging using large X-ray interferometers

    Science.gov (United States)

    Momose, Atsushi; Takeda, Tohoru; Yoneyama, Akio; Koyama, Ichiro; Itai, Yuji

    2001-07-01

    Large X-ray interferometers are developed for phase-contrast X-ray imaging aiming at medical applications. A monolithic X-ray interferometer and a separate one are studied, and currently a 25 mm×20 mm view area can be generated. This paper describes the strategy of our research program and some recent developments.

  16. Homeless Students and Academic Achievement: Evidence from a Large Urban Area

    Science.gov (United States)

    Tobin, Kerri J.

    2016-01-01

    Child homelessness has recently reached levels unprecedented in the United States since the Great Depression. Contemporary research has attempted to isolate the effects of homelessness on education, with mixed results. This study reports results from a study in one large urban area and finds that there is no meaningful difference in achievement…

  17. Large area flexible lighting foils using distributed bare LED dies on polyester substrates

    NARCIS (Netherlands)

    Ende, D.A. van den; Kusters, R.H.L.; Cauwe, M.; Waal, A. van der; Brand, J. van den

    2013-01-01

    Integration of LEDs on flexible foil substrates is of interest for flexible lighting applications and for backlights for flexible displays. Such a large area lighting device can be made by integrating a matrix of closely spaced LEDs on a flexible foil substrate. Preferably, these LEDs are integrated

  18. Nanotechnological Advances in Catalytic Thin Films for Green Large-Area Surfaces

    Directory of Open Access Journals (Sweden)

    Suzan Biran Ay

    2015-01-01

    Full Text Available Large-area catalytic thin films offer great potential for green technology applications in order to save energy, combat pollution, and reduce global warming. These films, either embedded with nanoparticles, shaped with nanostructuring techniques, hybridized with other systems, or functionalized with bionanotechnological methods, can include many different surface properties including photocatalytic, antifouling, abrasion resistant and mechanically resistive, self-cleaning, antibacterial, hydrophobic, and oleophobic features. Thus, surface functionalization with such advanced structuring methods is of significance to increase the performance and wide usage of large-area thin film coatings specifically for environmental remediation. In this review, we focus on methods to increase the efficiency of catalytic reactions in thin film and hence improve the performance in relevant applications while eliminating high cost with the purpose of widespread usage. However, we also include the most recent hybrid architectures, which have potential to make a transformational change in surface applications as soon as high quality and large area production techniques are available. Hence, we present and discuss research studies regarding both organic and inorganic methods that are used to structure thin films that have potential for large-area and eco-friendly coatings.

  19. Large-area and highly crystalline MoSe2 for optical modulator

    Science.gov (United States)

    Yin, Jinde; Chen, Hao; Lu, Wei; Liu, Mengli; Li, Irene Ling; Zhang, Min; Zhang, Wenfei; Wang, Jinzhang; Xu, Zihan; Yan, Peiguang; Liu, Wenjun; Ruan, Shuangchen

    2017-12-01

    Transition metal dichalcogenides (TMDs) have been successfully used as broadband optical modulator materials for pulsed fiber laser systems. However, the nonlinear optical absorptions of exfoliated TMDs are strongly limited by their nanoflakes morphology with uncontrollable lateral size and thickness. In this work, we provide an effective method to fully explore the nonlinear optical properties of MoSe2. Large-area and high quality lattice MoSe2 grown by chemical vapor deposition method was adopted as an optical modulator for the first time. The large-area MoSe2 shows excellent nonlinear optical absorption with a large modulation depth of 21.7% and small saturable intensity of 9.4 MW cm-2. After incorporating the MoSe2 optical modulator into fiber laser cavity as a saturable absorber, a highly stable Q-switching operation with single pulse energy of 224 nJ is achieved. The large-area MoSe2 possessing superior nonlinear optical properties compared to exfoliated nanoflakes affords possibility for the larger-area two-dimensional materials family as high performance optical devices.

  20. A new acoustic lens material for large area detectors in photoacoustic breast tomography

    NARCIS (Netherlands)

    Xia, W.; Piras, D.; van Hespen, Johannes C.G.; Steenbergen, Wiendelt; Manohar, Srirang

    2013-01-01

    Objectives We introduce a new acoustic lens material for photoacoustic tomography (PAT) to improve lateral resolution while possessing excellent acoustic acoustic impedance matching with tissue to minimize lens induced image artifacts. Background A large surface area detector due to its high

  1. Controllable chemical vapor deposition of large area uniform nanocrystalline graphene directly on silicon dioxide

    DEFF Research Database (Denmark)

    Sun, Jie; Lindvall, Niclas; Cole, Matthew T.

    2012-01-01

    Metal-catalyst-free chemical vapor deposition (CVD) of large area uniform nanocrystalline graphene on oxidized silicon substrates is demonstrated. The material grows slowly, allowing for thickness control down to monolayer graphene. The as-grown thin films are continuous with no observable pinholes...

  2. Long period gratings written in large-mode area photonic crystal fiber

    DEFF Research Database (Denmark)

    Nodop, D.; Linke, S.; Jansen, F.

    2008-01-01

    We report for the first time, to the best of our knowledge, on the fabrication and characterization of CO2-laser written long-period gratings in a large-mode area photonic crystal fiber with a core diameter of 25 mu m. The gratings have low insertion losses ( 10 d...

  3. 2π proportional counting chamber for large-area-coated β sources

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 86; Issue 6. 2 π proportional counting chamber for large-area-coated β sources ... A provision is made for change ofthe source and immediate measurement of source activity. These sources are used to calibrate the efficiency of contamination monitors at radiological ...

  4. The European Large-Area ISO Survey (ELAIS): the final band-merged catalogue

    DEFF Research Database (Denmark)

    Rowan-Robinson, M.; Lari, C.; Perez-Fournon, I.

    2004-01-01

    We present the final band-merged European Large-Area ISO Survey (ELAIS) Catalogue at 6.7, 15, 90 and 175 mum, and the associated data at U, g', r', i', Z, J, H, K and 20 cm. The origin of the survey, infrared and radio observations, data-reduction and optical identifications are briefly reviewed...

  5. The Large Area Telescope in the context of the extended Fermi mission

    International Nuclear Information System (INIS)

    Baldini, Luca

    2013-01-01

    Launched on June 11, 2008 with the goal of a 10-year lifetime, the Fermi observatory is nearing completion of the 5-year prime phase of the mission. In this paper we briefly review the prospects of the Large Area Telescope (the main instrument on board Fermi) in the context of the extended mission

  6. Large-area Fabry-Perot modulator based on electro-optic polymers

    DEFF Research Database (Denmark)

    Benter, Nils; Bertram, Ralph Peter; Soergel, Elisabeth

    2006-01-01

    We present a large-area electro-optic Fabry-Perot modulator utilizing a photoaddressable bis-azo polymer placed between two dielectric mirrors with an open aperture of 2 cm. A modulation efficientcy of 1% at an effective modulation voltage of 20 V for a wavelength of 1.55 mymeter is demonstrated...

  7. Process variations in surface nano geometries manufacture on large area substrates

    DEFF Research Database (Denmark)

    Calaon, Matteo; Hansen, Hans Nørgaard; Tosello, Guido

    2014-01-01

    The need of transporting, treating and measuring increasingly smaller biomedical samples has pushed the integration of a far reaching number of nanofeatures over large substrates size in respect to the conventional processes working area windows. Dimensional stability of nano fabrication processe...

  8. Cleanup of large areas contaminated as a result of a nuclear accident

    International Nuclear Information System (INIS)

    1989-01-01

    The purposes of the report are to provide an overview of the methodology and technology available to clean up contaminated areas and to give preliminary guidance on matters related to the planning, implementation and management of such cleanups. This report provides an integrated overview of important aspects related to the cleanup of very large areas contaminated as a result of a serious nuclear accident, including information on methods and equipment available to: characterize the affected area and the radioactive fallout; stabilize or isolate the contamination; and clean up contaminated urban, rural and forested areas. The report also includes brief sections on planning and management considerations and the transport and disposal of the large volumes of wastes arising from such cleanups. For the purposes of this report, nuclear accidents which could result in the deposition of decontamination over large areas if the outer containment fails badly include: 1) An accident with a nuclear weapon involving detonation of the chemical high explosive but little, if any, nuclear fission. 2) A major loss of medium/high level liquid waste (HLLW) due to an explosion/fire at a storage site for such waste. 3) An accident at a nuclear power plant (NPP), for example a loss of coolant accident, which results in some core disruption and fuel melting. 4) An accident at an NPP involving an uncontrolled reactivity excursion resulting in the violent ejection of a reactor core material and rupture of the containment building. 117 refs, 32 figs, 12 tabs

  9. Mapping regional patterns of large forest fires in Wildland-Urban Interface areas in Europe.

    Science.gov (United States)

    Modugno, Sirio; Balzter, Heiko; Cole, Beth; Borrelli, Pasquale

    2016-05-01

    Over recent decades, Land Use and Cover Change (LUCC) trends in many regions of Europe have reconfigured the landscape structures around many urban areas. In these areas, the proximity to landscape elements with high forest fuels has increased the fire risk to people and property. These Wildland-Urban Interface areas (WUI) can be defined as landscapes where anthropogenic urban land use and forest fuel mass come into contact. Mapping their extent is needed to prioritize fire risk control and inform local forest fire risk management strategies. This study proposes a method to map the extent and spatial patterns of the European WUI areas at continental scale. Using the European map of WUI areas, the hypothesis is tested that the distance from the nearest WUI area is related to the forest fire probability. Statistical relationships between the distance from the nearest WUI area, and large forest fire incidents from satellite remote sensing were subsequently modelled by logistic regression analysis. The first European scale map of the WUI extent and locations is presented. Country-specific positive and negative relationships of large fires and the proximity to the nearest WUI area are found. A regional-scale analysis shows a strong influence of the WUI zones on large fires in parts of the Mediterranean regions. Results indicate that the probability of large burned surfaces increases with diminishing WUI distance in touristic regions like Sardinia, Provence-Alpes-Côte d'Azur, or in regions with a strong peri-urban component as Catalunya, Comunidad de Madrid, Comunidad Valenciana. For the above regions, probability curves of large burned surfaces show statistical relationships (ROC value > 0.5) inside a 5000 m buffer of the nearest WUI. Wise land management can provide a valuable ecosystem service of fire risk reduction that is currently not explicitly included in ecosystem service valuations. The results re-emphasise the importance of including this ecosystem service

  10. Large-Area Synthesis of High-Quality Uniform Few-Layer MoTe2.

    Science.gov (United States)

    Zhou, Lin; Xu, Kai; Zubair, Ahmad; Liao, Albert D; Fang, Wenjing; Ouyang, Fangping; Lee, Yi-Hsien; Ueno, Keiji; Saito, Riichiro; Palacios, Tomás; Kong, Jing; Dresselhaus, Mildred S

    2015-09-23

    The controlled synthesis of large-area, atomically thin molybdenum ditelluride (MoTe2) crystals is crucial for its various applications based on the attractive properties of this emerging material. In this work, we developed a chemical vapor deposition synthesis to produce large-area, uniform, and highly crystalline few-layer 2H and 1T' MoTe2 films. It was found that these two different phases of MoTe2 can be grown depending on the choice of Mo precursor. Because of the highly crystalline structure, the as-grown few-layer 2H MoTe2 films display electronic properties that are comparable to those of mechanically exfoliated MoTe2 flakes. Our growth method paves the way for the large-scale application of MoTe2 in high-performance nanoelectronics and optoelectronics.

  11. A facility for the test of large area muon chambers at high rates

    CERN Document Server

    Agosteo, S; Belli, G; Bonifas, A; Carabelli, V; Gatignon, L; Hessey, N P; Maggi, M; Peigneux, J P; Reithler, H; Silari, Marco; Vitulo, P; Wegner, M

    2000-01-01

    Operation of large area muon detectors at the future Large Hadron Collider (LHC) will be characterized by large sustained hit rates over the whole area, reaching the range of kHz/\\scm. We describe a dedicated test zone built at CERN to test the performance and the aging of the muon chambers currently under development. A radioactive source delivers photons causing the sustained rate of random hits, while a narrow beam of high energy muons is used to directly calibrate the detector performance. A system of remotely controlled lead filters serves to vary the rate of photons over four orders of magnitude, to allow the study of performance as a function of rate.

  12. Scalable and reusable micro-bubble removal method to flatten large-area 2D materials

    Science.gov (United States)

    Pham, Phi H. Q.; Quach, Nhi V.; Li, Jinfeng; Burke, Peter J.

    2018-04-01

    Bubbles generated during electro-delamination and chemical etch during large-area two-dimensional (2D) material transfer has been shown to cause rippling, and consequently, results in tears and wrinkles in the transferred film. Here, we demonstrate a scalable and reusable method to remove surface adhered micro-bubbles by using hydrophobic surfaces modified by self-assembled monolayers (SAMs). Bubble removal allows the 2D film to flatten out and prevents the formation of defects. Electrical characterization was used to verify improved transfer quality and was confirmed by increased field-effect mobility and decreased sheet resistance. Raman spectroscopy was also used to validate enhanced electrical quality following transfer. The bubble removal method can be applied to an assortment of 2D materials using diverse hydrophobic SAM variants. Our studies can be integrated into large scale applications and will lead to improved large-area 2D electronics in general.

  13. A facility for the test of large-area muon chambers at high rates

    Energy Technology Data Exchange (ETDEWEB)

    Agosteo, S.; Altieri, S.; Belli, G.; Bonifas, A.; Carabelli, V.; Gatignon, L.; Hessey, N.; Maggi, M.; Peigneux, J.-P.; Reithler, H. E-mail: hans.reithler@cern.ch; Silari, M.; Vitulo, P.; Wegner, M

    2000-09-21

    Operation of large-area muon detectors at the future Large Hadron Collider (LHC) will be characterized by large sustained hit rates over the whole area, reaching the range of kHz cm{sup -2}. We describe a dedicated test zone built at CERN to test the performance and the aging of the muon chambers currently under development. A radioactive source delivers photons causing the sustained rate of random hits, while a narrow beam of high-energy muons is used to directly calibrate the detector performance. A system of remotely controlled lead filters serves to vary the rate of photons over four orders of magnitude, to allow the study of performance as a function of rate. (authors)

  14. Degenerate four wave mixing in large mode area hybrid photonic crystal fibers

    DEFF Research Database (Denmark)

    Petersen, Sidsel Rübner; Alkeskjold, Thomas Tanggaard; Lægsgaard, Jesper

    2013-01-01

    Spontaneous degenerate four wave mixing (FWM) is investigated in large mode area hybrid photonic crystal fibers, in which photonic bandgap guidance and index guidance is combined. Calculations show the parametric gain is maximum on the edge of a photonic bandgap, for a large range of pump...... wavelengths. The FWM products are observed on the edges of a transmission band experimentally, in good agreement with the numerical results. Thereby the bandedges can be used to control the spectral positions of FWM products through a proper fiber design. The parametric gain control combined with a large mode...... area fiber design potentially allows for power scaling of light at wavelengths not easily accessible with e.g. rare earth ions....

  15. Large area strain analysis using scanning transmission electron microscopy across multiple images

    International Nuclear Information System (INIS)

    Oni, A. A.; Sang, X.; LeBeau, J. M.; Raju, S. V.; Saxena, S.; Dumpala, S.; Broderick, S.; Rajan, K.; Kumar, A.; Sinnott, S.

    2015-01-01

    Here, we apply revolving scanning transmission electron microscopy to measure lattice strain across a sample using a single reference area. To do so, we remove image distortion introduced by sample drift, which usually restricts strain analysis to a single image. Overcoming this challenge, we show that it is possible to use strain reference areas elsewhere in the sample, thereby enabling reliable strain mapping across large areas. As a prototypical example, we determine the strain present within the microstructure of a Ni-based superalloy directly from atom column positions as well as geometric phase analysis. While maintaining atomic resolution, we quantify strain within nanoscale regions and demonstrate that large, unit-cell level strain fluctuations are present within the intermetallic phase

  16. Techno-economic assessment of novel vanadium redox flow batteries with large-area cells

    Science.gov (United States)

    Minke, Christine; Kunz, Ulrich; Turek, Thomas

    2017-09-01

    The vanadium redox flow battery (VRFB) is a promising electrochemical storage system for stationary megawatt-class applications. The currently limited cell area determined by the bipolar plate (BPP) could be enlarged significantly with a novel extruded large-area plate. For the first time a techno-economic assessment of VRFB in a power range of 1 MW-20 MW and energy capacities of up to 160 MWh is presented on the basis of the production cost model of large-area BPP. The economic model is based on the configuration of a 250 kW stack and the overall system including stacks, power electronics, electrolyte and auxiliaries. Final results include a simple function for the calculation of system costs within the above described scope. In addition, the impact of cost reduction potentials for key components (membrane, electrode, BPP, vanadium electrolyte) on stack and system costs is quantified and validated.

  17. Large-area burns with pandrug-resistant Pseudomonas aeruginosa infection and respiratory failure.

    Science.gov (United States)

    Ning, Fang-Gang; Zhao, Xiao-Zhuo; Bian, Jing; Zhang, Guo-An

    2011-02-01

    Infection due to pandrug-resistant Pseudomonas aeruginosa (PDRPA) has become a challenge in clinical practice. The aim of this research was to summarize the treatment of large-area burns (60% - 80%) with PDRPA infection and respiratory failure in our hospital over the last two years, and to explore a feasible treatment protocol for such patients. We retrospectively analyzed the treatment of five patients with large-area burns accompanied by PDRPA infection and respiratory failure transferred to our hospital from burn units in hospitals in other Chinese cities from January 2008 to February 2010. Before PDRPA infection occurred, all five patients had open wounds with large areas of granulation because of the failure of surgery and dissolving of scar tissue; they had also undergone long-term administration of carbapenems. This therapy included ventilatory support, rigorous repair of wounds, and combined antibiotic therapy targeted at drug-resistance mechanisms, including carbapenems, ciprofloxacin, macrolide antibiotics and β-lactamase inhibitors. Four patients recovered from burns and one died after therapy. First, compromised immunity caused by delayed healing of burn wounds in patients with large-area burns and long-term administration of carbapenems may be the important factors in the initiation and progression of PDRPA infection. Second, if targeted at drug-resistance mechanisms, combined antibiotic therapy using carbapenems, ciprofloxacin, macrolide antibiotics and β-lactamase inhibitors could effectively control PDRPA infection. Third, although patients with large-area burns suffered respiratory failure and had high risks from anesthesia and surgery, only aggressive skin grafting with ventilatory support could control the infection and save lives. Patients may not be able to tolerate a long surgical procedure, so the duration of surgery should be minimized, and the frequency of surgery increased.

  18. Two-group modeling of interfacial area transport in large diameter channels

    Energy Technology Data Exchange (ETDEWEB)

    Schlegel, J.P., E-mail: schlegelj@mst.edu [Department of Mining and Nuclear Engineering, Missouri University of Science and Technology, 301 W 14th St., Rolla, MO 65409 (United States); Hibiki, T.; Ishii, M. [School of Nuclear Engineering, Purdue University, 400 Central Dr., West Lafayette, IN 47907 (United States)

    2015-11-15

    Highlights: • Implemented updated constitutive models and benchmarking method for IATE in large pipes. • New model and method with new data improved the overall IATE prediction for large pipes. • Not all conditions well predicted shows that further development is still required. - Abstract: A comparison of the existing two-group interfacial area transport equation source and sink terms for large diameter channels with recently collected interfacial area concentration measurements (Schlegel et al., 2012, 2014. Int. J. Heat Fluid Flow 47, 42) has indicated that the model does not perform well in predicting interfacial area transport outside of the range of flow conditions used in the original benchmarking effort. In order to reduce the error in the prediction of interfacial area concentration by the interfacial area transport equation, several constitutive relations have been updated including the turbulence model and relative velocity correlation. The transport equation utilizing these updated models has been modified by updating the inter-group transfer and Group 2 coalescence and disintegration kernels using an expanded range of experimental conditions extending to pipe sizes of 0.304 m [12 in.], gas velocities of up to nearly 11 m/s [36.1 ft/s] and liquid velocities of up to 2 m/s [6.56 ft/s], as well as conditions with both bubbly flow and cap-bubbly flow injection (Schlegel et al., 2012, 2014). The modifications to the transport equation have resulted in a decrease in the RMS error for void fraction and interfacial area concentration from 17.32% to 12.3% and 21.26% to 19.6%. The combined RMS error, for both void fraction and interfacial area concentration, is below 15% for most of the experiments used in the comparison, a distinct improvement over the previous version of the model.

  19. Activity of CERN and LNF groups on large area GEM detectors

    Energy Technology Data Exchange (ETDEWEB)

    Alfonsi, M. [CERN, Geneva (Switzerland); Bencivenni, G. [Laboratori Nazionali di Frascati dell' INFN, Frascati (Italy); Brock, I. [Physikalisches Institute der Universitat Bonn, Bonn (Germany); Cerioni, S. [Laboratori Nazionali di Frascati dell' INFN, Frascati (Italy); Croci, G.; David, E. [CERN, Geneva (Switzerland); De Lucia, E. [Laboratori Nazionali di Frascati dell' INFN, Frascati (Italy); De Oliveira, R. [CERN, Geneva (Switzerland); De Robertis, G. [Sezione INFN di Bari, Bari (Italy); Domenici, D., E-mail: Danilo.Domenici@lnf.infn.i [Laboratori Nazionali di Frascati dell' INFN, Frascati (Italy); Duarte Pinto, S. [CERN, Geneva (Switzerland); Felici, G.; Gatta, M.; Jacewicz, M. [Laboratori Nazionali di Frascati dell' INFN, Frascati (Italy); Loddo, F. [Sezione INFN di Bari, Bari (Italy); Morello, G. [Dipeartimento di Fisica Universita della Calabria e INFN, Cosenza (Italy); Pistilli, M. [Laboratori Nazionali di Frascati dell' INFN, Frascati (Italy); Ranieri, A. [Sezione INFN di Bari, Bari (Italy); Ropelewski, L. [CERN, Geneva (Switzerland); Sauli, F. [TERA Foundation, Novara (Italy)

    2010-05-21

    We report on the activity of CERN and INFN-LNF groups on the development of large area GEM detectors. The two groups work together within the RD51 Collaboration, to aim at the development of Micro-pattern Gas detectors technologies. The vast request for large area foils by the GEM community has driven a change in the manufacturing procedure by the TS-DEM-PMT laboratory, needed to overcome the previous size limitation of 450x450mm{sup 2}. Now a single-mask technology is used allowing foils to be made as large as 450x2000mm{sup 2}. The limitation in the short size, due to the definite width of the raw material, can be overcome by splicing more foils together. A 10x10cm{sup 2} GEM detector with the new single-mask foil has been tested with X-rays and the results are shown. Possible future applications for large area GEM are the TOTEM experiment upgrade at CERN, and the KLOE-2 experiment at the Dafne {Phi}-factory in Frascati.

  20. Activity of CERN and LNF groups on large area GEM detectors

    International Nuclear Information System (INIS)

    Alfonsi, M.; Bencivenni, G.; Brock, I.; Cerioni, S.; Croci, G.; David, E.; De Lucia, E.; De Oliveira, R.; De Robertis, G.; Domenici, D.; Duarte Pinto, S.; Felici, G.; Gatta, M.; Jacewicz, M.; Loddo, F.; Morello, G.; Pistilli, M.; Ranieri, A.; Ropelewski, L.; Sauli, F.

    2010-01-01

    We report on the activity of CERN and INFN-LNF groups on the development of large area GEM detectors. The two groups work together within the RD51 Collaboration, to aim at the development of Micro-pattern Gas detectors technologies. The vast request for large area foils by the GEM community has driven a change in the manufacturing procedure by the TS-DEM-PMT laboratory, needed to overcome the previous size limitation of 450x450mm 2 . Now a single-mask technology is used allowing foils to be made as large as 450x2000mm 2 . The limitation in the short size, due to the definite width of the raw material, can be overcome by splicing more foils together. A 10x10cm 2 GEM detector with the new single-mask foil has been tested with X-rays and the results are shown. Possible future applications for large area GEM are the TOTEM experiment upgrade at CERN, and the KLOE-2 experiment at the Dafne Φ-factory in Frascati.

  1. Tianmujian caldera. A potential area for locating rich and large uranium deposit

    International Nuclear Information System (INIS)

    Lin Ziyu; Xu Jinshan; Chen Mingzhuo; Jiang Jinyuan; Fan Honghai; Cheng Qi

    2001-01-01

    Based on the comprehensive analysis on geologic, remote sensing, gravimetric, magnetic and geochemical data, and the field geologic investigation, the author has preliminarily ascertained the formation and the distribution characteristics of the Tianmujian caldera, and recognized the porphyroclastic lava system which is extensively distributed in the area. The authors suggest that the Tianmujian volcanic basin experienced two evolution stages--the thermal uplifting and the formation of caldera, that large concealed uranium-rich granitic massif occurs in the area, and during the vertical evolution process the uranium showed its concentration in the lower part and depletion in the upper part, and large amount of ore-forming material moved upward along with the magmatic hydrothermals entering the caldera to form uranium deposit. In addition, it is clarified that the NE-NW rhombic-formed basement structural pattern is predominated by the NE-trending fault. At the same time, the important role of the basement faults in controlling the magmatic activities, in the formation of volcanic basins, as well as the formation of uranium mineralization is emphasized. On the basis of the above comprehensive analysis the authors suggest that the Tianmujian caldera is a quite favourable potential area for possessing the basic conditions necessary for the formation of rich and large uranium deposit including uranium 'source, migration, concentration, preservation' and favourable multiple metallogenic information is displayed in the Tianmujian area

  2. Effects of electrolyte gating on photoluminescence spectra of large-area WSe2monolayer films

    KAUST Repository

    Matsuki, Keiichiro; Pu, Jiang; Kozawa, Daichi; Matsuda, Kazunari; Li, Lain-Jong; Takenobu, Taishi

    2016-01-01

    We fabricated electric double-layer transistors comprising large-area WSe2 monolayers and investigated the effects of electrolyte gating on their photoluminescence (PL) spectra. Using the efficient gating effects of electric double layers, we succeeded in the application of a large electric field (>107Vcm%1) and the accumulation of high carrier density (>1013cm%2). As a result, we observed PL spectra based on both positively and negatively charged excitons and their gate-voltage-dependent redshifts, suggesting the effects of both an electric field and charge accumulation. © 2016 The Japan Society of Applied Physics.

  3. Monolayer graphene-insulator-semiconductor emitter for large-area electron lithography

    Science.gov (United States)

    Kirley, Matthew P.; Aloui, Tanouir; Glass, Jeffrey T.

    2017-06-01

    The rapid adoption of nanotechnology in fields as varied as semiconductors, energy, and medicine requires the continual improvement of nanopatterning tools. Lithography is central to this evolving nanotechnology landscape, but current production systems are subject to high costs, low throughput, or low resolution. Herein, we present a solution to these problems with the use of monolayer graphene in a graphene-insulator-semiconductor (GIS) electron emitter device for large-area electron lithography. Our GIS device displayed high emission efficiency (up to 13%) and transferred large patterns (500 × 500 μm) with high fidelity (industries and opening opportunities in nanomanufacturing.

  4. Effects of electrolyte gating on photoluminescence spectra of large-area WSe2monolayer films

    KAUST Repository

    Matsuki, Keiichiro

    2016-05-24

    We fabricated electric double-layer transistors comprising large-area WSe2 monolayers and investigated the effects of electrolyte gating on their photoluminescence (PL) spectra. Using the efficient gating effects of electric double layers, we succeeded in the application of a large electric field (>107Vcm%1) and the accumulation of high carrier density (>1013cm%2). As a result, we observed PL spectra based on both positively and negatively charged excitons and their gate-voltage-dependent redshifts, suggesting the effects of both an electric field and charge accumulation. © 2016 The Japan Society of Applied Physics.

  5. Fast printing of thin, large area, ITO free electrochromics on flexible barrier foil

    DEFF Research Database (Denmark)

    Søndergaard, Roar R.; Hösel, Markus; Jørgensen, Mikkel

    2013-01-01

    Processing of large area, indium tin oxide (ITO) free electrochromic (EC) devices has been carried out using roll-toroll (R2R) processing. By use of very fine high-conductive silver grids with a hexagonal structure, it is possible to achieve good transparency of the electrode covered substrates...... and when used in EC devices switching times are similar to corresponding ITO devices. This is obtained without the uneven switching of larger areas, which is generally observed when using ITO because of its high-sheet resistance. The silver electrode structures for 18 ×18 cm2 devices can be processed...

  6. The European large area ISO survey - III. 90-mu m extragalactic source counts

    DEFF Research Database (Denmark)

    Efstathiou, A.; Oliver, S.; Rowan-Robinson, M.

    2000-01-01

    We present results and source counts at 90 mum extracted from the preliminary analysis of the European Large Area ISO Survey (ELAIS). The survey covered about 12 deg(2) of the sky in four main areas and was carried out with the ISOPHOT instrument onboard the Infrared Space Observatory (ISO...... or small groups of galaxies, suggesting that the sample may include a significant fraction of luminous infrared galaxies. The source counts extracted from a reliable subset of the detected sources are in agreement with strongly evolving models of the starburst galaxy population....

  7. On the stability of large-area Al-p-Si junction

    International Nuclear Information System (INIS)

    Tsyganov, Yu.S.

    2006-01-01

    Design of silicon radiation detector made of 12 kΩ · cm p-silicon with both amine- and amine-free hardeners epoxy resin junction edge passivation is presented. Before producing large-area detectors for measurements of efficiency of evaporation residues collection at the focal plane of the Dubna Gas-Filled Recoil Separator (DGFRS), a set of small-area test detectors was produced. Stability of the Al-(p)Si junction has been studied for a long time. Estimate of a realistic lifetime for the mentioned type of Al-Si rectifying junction is done

  8. Highly segmented large-area hybrid photodiodes with bialkali photocathodes and enclosed VLSI readout electronics

    CERN Document Server

    Braem, André; Filthaut, Frank; Go, A; Joram, C; Weilhammer, Peter; Wicht, P; Dulinski, W; Séguinot, Jacques; Wenzel, H; Ypsilantis, Thomas

    2000-01-01

    We report on the principles, design, fabrication, and operation of a highly segmented, large-area hybrid photodiode, which is being developed in the framework of the LHCb RICH project. The device consists of a cylindrical, 127 mm diameter vacuum envelope capped with a spherical borosilicate UV-glass entrance window, with an active-to-total-area fraction of 81A fountain-focusing electron optics is used to demagnify the image onto a 50 mm diameter silicon sensor, containing 2048 pads of size 1*1 mm/sup 2/. (10 refs).

  9. Radiocaesium levels in roe deer and wild boar in two large forest areas in Austria

    International Nuclear Information System (INIS)

    Tataruch, F.; Klansek, E.; Schoenhofer, F.

    1996-01-01

    A report is given on the course of radiocaesium contamination in roe deer and wild boar in two large forest areas in Austria. In autumn 1987 and winter 1987/88 radiocaesium levels rose to values higher than those recorded in 1986 in these regions. The reason for this increase was the very specific feeding selection of roe deer in these forest areas resulting in the ingestion of an unusual high amount of blueberries, ferns and mushrooms. An explanation for the changes of wild boar's contamination has not been found yet, but possible reasons are discussed. (author)

  10. Bend-resistant large mode area fiber with novel segmented cladding

    Science.gov (United States)

    Ma, Shaoshuo; Ning, Tigang; Pei, Li; Li, Jing; Zheng, Jingjing

    2018-01-01

    A novel structure of segment cladding fiber (SCF) with characteristics of bend-resistance and large-mode-area (LMA) is proposed. In this new structure, the high refractive index (RI) core is periodically surrounded by high RI fan-segmented claddings. Numerical investigations show that effective single-mode operation of the proposed fiber with mode field area of 700 μm2 can be achieved when the bending radius is 15 cm. Besides, this fiber is insensitive to the bending orientation at the ranging of [-180°, 180°]. The proposed design shows great potential in high power fiber lasers and amplifiers with compact structure.

  11. Thick and large area PIN diodes for hard X-ray astronomy

    CERN Document Server

    Ota, N; Sugizaki, M; Kaneda, M; Tamura, T; Ozawa, H; Kamae, T; Makishima, K; Takahashi, T; Tashiro, M; Fukazawa, Y; Kataoka, J; Yamaoka, K; Kubo, S; Tanihata, C; Uchiyama, Y; Matsuzaki, K; Iyomoto, N; Kokubun, M; Nakazawa, T; Kubota, A; Mizuno, T; Matsumoto, Y; Isobe, N; Terada, Y; Sugiho, M; Onishi, T; Kubo, H; Ikeda, H; Nomachi, M; Ohsugi, T; Muramatsu, M; Akahori, H

    1999-01-01

    Thick and large area PIN diodes for the hard X-ray astronomy in the 10-60 keV range are developed. To cover this energy range in a room temperature and in a low background environment, Si PIN junction diodes of 2 mm in thickness with 2.5 cm sup 2 in effective area were developed, and will be used in the bottom of the Phoswich Hard X-ray Detector (HXD), on-board the ASTRO-E satellite. Problems related to a high purity Si and a thick depletion layer during our development and performance of the PIN diodes are presented in detail.

  12. A large area two-dimensional position sensitive multiwire proportional detector

    CERN Document Server

    Moura, M M D; Souza, F A; Alonso, E E; Fujii, R J; Meyknecht, A B; Added, N; Aissaoui, N; Cardenas, W H Z; Ferraretto, M D; Schnitter, U; Szanto, E M; Szanto de Toledo, A; Yamamura, M S; Carlin, N

    1999-01-01

    Large area two-dimensional position sensitive multiwire proportional detectors were developed to be used in the study of light heavy-ion nuclear reactions at the University of Sao Paulo Pelletron Laboratory. Each detector has a 20x20 cm sup 2 active area and consists of three grids (X-position, anode and Y-position) made of 25 mu m diameter gold plated tungsten wires. The position is determined through resistive divider chains. Results for position resolution, linearity and efficiency as a function of energy and position for different elements are reported.

  13. Highlights of a recycling behaviour study in South Africa’s large urban areas

    CSIR Research Space (South Africa)

    Strydom, WF

    2012-10-01

    Full Text Available behaviour study in South Africa?s large urban areas WF STRYDOM CSIR Natural Resources and the Environment, PO Box 395, Pretoria 0001 Email: wstrydom@csir.co.za ? www.csir.co.za INTRODUCTION The recently promulgated National Environmental Management... representative sample of 2 004 respondents in 11 of the larger South African urban areas, including all the metropolitan municipalities. The survey was conducted in November 2010, before the Waste Act was widely implemented. The objective of the study was...

  14. Bend compensated large-mode-area fibers: achieving robust single-modedness with transformation optics.

    Science.gov (United States)

    Fini, John M; Nicholson, Jeffrey W

    2013-08-12

    Fibers with symmetric bend compensated claddings are proposed, and demonstrate performance much better than conventional designs. These fibers can simultaneously achieve complete HOM suppression, negligible bend loss, and mode area >1000 square microns. The robust single-modedness of these fibers offers a path to overcoming mode instability limits on high-power amplifiers and lasers. The proposed designs achieve many of the advantages of our previous (asymmetric) bend compensation strategy in the regime of moderately large area, and are much easier to fabricate and utilize.

  15. ITO with embedded silver grids as transparent conductive electrodes for large area organic solar cells

    DEFF Research Database (Denmark)

    Patil, Bhushan Ramesh; Mirsafaei, Mina; Cielecki, Pawel Piotr

    2017-01-01

    In this work, development of semi-transparent electrodes for efficient large area organic solar cells (OSCs) has been demonstrated. Electron beam evaporated silver grids were embedded in commercially available ITO coatings on glass, through a standard negative photolithography process, in order...... patterns. Solution processed bulk heterojunction OSCs based on PTB7:[70]PCBM were fabricated on top of these electrodes with cell areas of 4.38 cm2, and the performance of these OSCs was compared to reference cells fabricated on pure ITO electrodes. The Fill Factor of the large-scale OSCs fabricated on ITO...... with embedded Ag grids was enhanced by 18 % for the line grids pattern and 30 % for the square grids pattern compared to that of the reference OSCs. The increase in the Fill Factor was directly correlated to the decrease in the series resistance of the OSCs. The maximum power conversion efficiency (PCE...

  16. Large-Area All-Textile Pressure Sensors for Monitoring Human Motion and Physiological Signals.

    Science.gov (United States)

    Liu, Mengmeng; Pu, Xiong; Jiang, Chunyan; Liu, Ting; Huang, Xin; Chen, Libo; Du, Chunhua; Sun, Jiangman; Hu, Weiguo; Wang, Zhong Lin

    2017-11-01

    Wearable pressure sensors, which can perceive and respond to environmental stimuli, are essential components of smart textiles. Here, large-area all-textile-based pressure-sensor arrays are successfully realized on common fabric substrates. The textile sensor unit achieves high sensitivity (14.4 kPa -1 ), low detection limit (2 Pa), fast response (≈24 ms), low power consumption (sensor is demonstrated to be able to recognize finger movement, hand gestures, acoustic vibrations, and real-time pulse wave. Furthermore, large-area sensor arrays are successfully fabricated on one textile substrate to spatially map tactile stimuli and can be directly incorporated into a fabric garment for stylish designs without sacrifice of comfort, suggesting great potential in smart textiles or wearable electronics. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Large-area imaging micro-well detectors for high-energy astrophysics

    CERN Document Server

    Deines-Jones, P; Hunter, S D; Jahoda, K; Owens, S M

    2002-01-01

    Micro-well detectors are pixelized imaging sensors that can be inexpensively fabricated in very large arrays. Owing to their intrinsic gain and operation at room temperature, they can be instrumented at very low power, per unit area, making them valuable for a variety of space-flight applications where wide-angle X-ray imaging or large-area particle tracking is required. For example, micro-well detectors have been chosen as the focal plane imager for Lobster-ISS, a proposed soft X-ray all-sky monitor. We have fabricated detectors which image X-rays with 200 mu m FWHM resolution at 3 keV. In agreement with other groups using similar geometries, we find nominal proportional counter energy resolution (20% at 6 keV in P-10), and stable operation at gas gains up to 30,000.

  18. Clinical observation on the reconstruction of large areas lower eyelid defect with Medpor spacer graft

    Directory of Open Access Journals (Sweden)

    Hai-Yan Li

    2014-08-01

    Full Text Available AIM: To observe the effects of porous polyethylene(Medporas a spacer graft in the reconstruction of large areas eyelid defect after the operation of malignant tumors of lower eyelids.METHODS: Nineteen cases(19 eyesof malignant tumors of lower eyelid underwent the eyelid reconstruction were selected. Medpor lower eyelid inserts implantation were used to replace tarsal joint sliding conjunctival flap and pedicle flap, and repaired full-thickness lower eyelid defects then underwent eyelid reconstruction. RESULTS: Appearance of eyelids and functional improvements were satisfactory with no stimulation on the eyeball and no effect on the visual function. Implants is with no absorption, shift, exclusion or infection and no tumor recurrence in all cases during the follow up for 6-36mo.CONCLUSION: Medpor lower eyelid inserts implantation can instead tarsal plate for the reconstruction of medium to large areas lower eyelid defect, which is easy performing with rare complications. It is an ideal alternatives of tarsal plate.

  19. ArCLight—A Compact Dielectric Large-Area Photon Detector

    Directory of Open Access Journals (Sweden)

    Martin Auger

    2018-02-01

    Full Text Available ArgonCube Light readout system (ArCLight is a novel device for detecting scintillation light over large areas with Photon Detection Efficiency (PDE of the order of a few percent. Its robust technological design allows for efficient use in large-volume particle detectors, such as Liquid Argon Time Projection Chambers (LArTPCs or liquid scintillator detectors. Due to its dielectric structure it can be placed inside volumes with high electric field. It could potentially replace vacuum PhotoMultiplier Tubes (PMTs in applications where high PDE is not required. The photon detection efficiency for a 10 × 10 cm2 detector prototype was measured to be in the range of 0.8% to 2.2% across the active area.

  20. Calibration of atomic trajectories in a large-area dual-atom-interferometer gyroscope

    Science.gov (United States)

    Yao, Zhan-Wei; Lu, Si-Bin; Li, Run-Bing; Luo, Jun; Wang, Jin; Zhan, Ming-Sheng

    2018-01-01

    We propose and demonstrate a method for calibrating atomic trajectories in a large-area dual-atom-interferometer gyroscope. The atom trajectories are monitored by modulating and delaying the Raman transition, and they are precisely calibrated by controlling the laser orientation and the bias magnetic field. To improve the immunity to the gravity effect and the common phase noise, the symmetry and the overlap of two large-area atomic interference loops are optimized by calibrating the atomic trajectories and by aligning the Raman-laser orientations. The dual-atom-interferometer gyroscope is applied in the measurement of the Earth's rotation. The sensitivity is 1.2 ×10-6 rad s -1 Hz-1/2, and the long-term stability is 6.2 ×10-8 rad/s at 2000 s.

  1. Large-area WSe2 electric double layer transistors on a plastic substrate

    KAUST Repository

    Funahashi, Kazuma; Pu, Jiang; Li, Ming Yang; Li, Lain-Jong; Iwasa, Yoshihiro; Takenobu, Taishi

    2015-01-01

    Due to the requirements for large-area, uniform films, currently transition metal dichalcogenides (TMDC) cannot be used in flexible transistor industrial applications. In this study, we first transferred chemically grown large-area WSe2 monolayer films from the as-grown sapphire substrates to the flexible plastic substrates. We also fabricated electric double layer transistors using the WSe2 films on the plastic substrates. These transistors exhibited ambipolar operation and an ON/OFF current ratio of ∼104, demonstrating chemically grown WSe2 transistors on plastic substrates for the first time. This achievement can be an important first step for the next-generation TMDC based flexible devices. © 2015 The Japan Society of Applied Physics.

  2. A Novel Method of Fabricating Flexible Transparent Conductive Large Area Graphene Film

    International Nuclear Information System (INIS)

    Fan Tian-Ju; Yuan Chun-Qiu; Tang Wei; Tong Song-Zhao; Huang Wei; Min Yong-Gang; Liu Yi-Dong; Epstein, Arthur J.

    2015-01-01

    We fabricate flexible conductive and transparent graphene films on position-emission-tomography substrates and prepare large area graphene films by graphite oxide sheets with the new technical process. The multi-layer graphene oxide sheets can be chemically reduced by HNO 3 and HI to form a highly conductive graphene film on a substrate at lower temperature. The reduced graphene oxide sheets show a high conductivity sheet with resistance of 476 Ω/sq and transmittance of 76% at 550 nm (6 layers). The technique used to produce the transparent conductive graphene thin film is facile, inexpensive, and can be tunable for a large area production applied for electronics or touch screens. (paper)

  3. Large-area atmospheric Cherenkov detectors for high-energy gamma-ray astronomy

    International Nuclear Information System (INIS)

    Ong, R.A.

    1996-01-01

    This paper describes the development of new ground-based gamma-ray detectors to explore the energy region between 20 and 200 GeV. This region in energy is interesting because it is currently unexplored by any experiment. The proposed detectors use the atmospheric Cherenkov technique, in which Cherenkov radiation produced in the gamma-ray air showers is detected using mirrors and light-sensitive devices. The important feature of the proposed experiments is the use of large mirror collection areas, which should allow for a significant improvement (i.e. reduction) in energy threshold over existing experiments. Large mirror areas are available for relatively low cost at central tower solar power plants, and there are two groups developing gamma-ray experiments using solar heliostat arrays. This paper summarizes the progress in the design of experiments using this novel approach

  4. An open-flow pulse ionization chamber for alpha spectrometry of large-area samples

    International Nuclear Information System (INIS)

    Johansson, L.; Roos, B.; Samuelsson, C.

    1992-01-01

    The presented open-flow pulse ionization chamber was developed to make alpha spectrometry on large-area surfaces easy. One side of the chamber is left open, where the sample is to be placed. The sample acts as a chamber wall and therby defeins the detector volume. The sample area can be as large as 400 cm 2 . To prevent air from entering the volume there is a constant gas flow through the detector, coming in at the bottom of the chamber and leaking at the sides of the sample. The method results in good energy resolution and has considerable applicability in the retrospective radon research. Alpha spectra obtained in the retrospective measurements descend from 210 Po, built up in the sample from the radon daughters recoiled into a glass surface. (au)

  5. Multicolor emission from large-area porous thin films constructed of nanowires of small organic molecules

    International Nuclear Information System (INIS)

    Wang Zhechen; Ding Xunlei; Ma Yanping; Xue Wei; He Shenggui; Xiao Wenchang

    2008-01-01

    We describe a facile low-temperature physical vapor deposition approach to fabricate porous network thin films constructed of nanowires of small organic molecules on a large area. Supermolecular assemblies of pyrene nanowires based on a combination of van der Waals forces and π-π stacking tend to hierarchically self-assemble to form uniform porous films using our techniques. The morphology of the films is studied and we also study several reasons influencing the process of assembly such as evaporation temperature, deposition temperature, and different kinds of substrate. The deposition temperature is determined to be the main reason for hierarchical aggregation. Typically prepared films exhibit unique optical properties, that is, multicolor red-green-blue emissions. This novel method can be applied to other organic molecular systems and may be potentially used to place nanoscaled building blocks directly on solid surfaces for fabricating large-area nanostructure-based flat screens.

  6. Multicolor emission from large-area porous thin films constructed of nanowires of small organic molecules

    Science.gov (United States)

    Wang, Zhe-Chen; Xiao, Wen-Chang; Ding, Xun-Lei; Ma, Yan-Ping; Xue, Wei; He, Sheng-Gui

    2008-12-01

    We describe a facile low-temperature physical vapor deposition approach to fabricate porous network thin films constructed of nanowires of small organic molecules on a large area. Supermolecular assemblies of pyrene nanowires based on a combination of van der Waals forces and π-π stacking tend to hierarchically self-assemble to form uniform porous films using our techniques. The morphology of the films is studied and we also study several reasons influencing the process of assembly such as evaporation temperature, deposition temperature, and different kinds of substrate. The deposition temperature is determined to be the main reason for hierarchical aggregation. Typically prepared films exhibit unique optical properties, that is, multicolor red-green-blue emissions. This novel method can be applied to other organic molecular systems and may be potentially used to place nanoscaled building blocks directly on solid surfaces for fabricating large-area nanostructure-based flat screens.

  7. A gas proportional scintillation counter for use in large area detector systems without photomultipliers

    International Nuclear Information System (INIS)

    Baruch, J.E.F.; Brooke, G.; Kellerman, E.W.; Bateman, J.E.; Connolly, J.F.

    1979-01-01

    The properties of a prototype gas proportional scintillation (GPS) detector module are described. The module (25X25X14cm 3 ) is intended to form the basic unit of large area (up to approximately 100 m 2 ) calorimetric cosmic ray burst detector. Ionisation from particle tracks in the module is collected onto a point electrode where the GPS signal is generated. A concave mirror focusses this point source onto the end of a fibre optic light guide. In the proposed large area detector these fibres are brought together onto a low light level TV camera which performs the readout. The prototype module has demonstrated an adequate light output for the detection of single muons by such a readout system and also permitted the investigation of the main operating parameters (gas mixture, EHT, pressure, etc) and operational requirements such as proportionality and long term stability. (Auth.)

  8. Large-area WSe2 electric double layer transistors on a plastic substrate

    KAUST Repository

    Funahashi, Kazuma

    2015-04-27

    Due to the requirements for large-area, uniform films, currently transition metal dichalcogenides (TMDC) cannot be used in flexible transistor industrial applications. In this study, we first transferred chemically grown large-area WSe2 monolayer films from the as-grown sapphire substrates to the flexible plastic substrates. We also fabricated electric double layer transistors using the WSe2 films on the plastic substrates. These transistors exhibited ambipolar operation and an ON/OFF current ratio of ∼104, demonstrating chemically grown WSe2 transistors on plastic substrates for the first time. This achievement can be an important first step for the next-generation TMDC based flexible devices. © 2015 The Japan Society of Applied Physics.

  9. Large-Area Binary Blazed Grating Coupler between Nanophotonic Waveguide and LED

    Directory of Open Access Journals (Sweden)

    Hongqiang Li

    2014-01-01

    Full Text Available A large-area binary blazed grating coupler for the arrayed waveguide grating (AWG demodulation integrated microsystem on silicon-on-insulator (SOI was designed for the first time. Through the coupler, light can be coupled into the SOI waveguide from the InP-based C-band LED for the AWG demodulation integrated microsystem to function. Both the length and width of the grating coupler are 360 μm, as large as the InP-based C-band LED light emitting area in the system. The coupler was designed and optimized based on the finite difference time domain method. When the incident angle of the light source is 0°, the coupling efficiency of the binary blazed grating is 40.92%, and the 3 dB bandwidth is 72 nm at a wavelength of 1550 nm.

  10. Development of an Evaluation Methodology for Loss of Large Area induced from extreme events

    International Nuclear Information System (INIS)

    Kim, Sok Chul; Park, Jong Seuk; Kim, Byung Soon; Jang, Dong Ju; Lee, Seung Woo

    2015-01-01

    USNRC announced several regulatory requirements and guidance documents regarding the event of loss of large area including 10CFR 50.54(hh), Regulatory Guide 1.214 and SRP 19.4. In Korea, consideration of loss of large area has been limitedly taken into account for newly constructing NPPs as voluntary based. In general, it is hardly possible to find available information on methodology and key assumptions for the assessment of LOLA due to 'need to know based approach'. Urgent needs exists for developing country specific regulatory requirements, guidance and evaluation methodology by themselves with the consideration of their own geographical and nuclear safety and security environments. Currently, Korea Hydro and Nuclear Power Company (KHNP) has developed an Extended Damage Mitigation Guideline (EDMG) for APR1400 under contract with foreign consulting company. The submittal guidance NEI 06-12 related to B.5.b Phase 2 and 3 focused on unit-wise mitigation strategy instead of site level mitigation or response strategy. Phase 1 mitigating strategy and guideline for LOLA (Loss of Large Area) provides emphasis on site level arrangement including cooperative networking outside organizations and agile command and control system. Korea Institute of Nuclear Safety has carried out a pilot in-house research project to develop the methodology and guideline for evaluation of LOLA since 2014. This paper introduces the summary of major results and outcomes of the aforementioned research project. After Fukushima Dai-Ichi accident, the awareness on countering the event of loss of large area induced from extreme man-made hazards or extreme beyond design basis external event. Urgent need exists to develop regulatory guidance for coping with this undesirable situation, which has been out of consideration at existing nuclear safety regulatory framework due to the expectation of rare possibility of occurrence

  11. Large-area thin self-supporting carbon foils with MgO coatings

    Science.gov (United States)

    Stolarz, Anna; Maier-Komor, Peter

    2002-03-01

    Large area self-supporting carbon foils in the thickness of range of 8-22 μg/cm 2, coated with approximately 4 μg/cm 2 MgO have been prepared by e-gun evaporation. They were mounted on frames with apertures of 130 cm 2. Problems related to the parting agent preparation, floating procedure, and mounting onto frames are discussed. Special precautions necessary to avoid damage during foil drying, storage and transportation are suggested.

  12. X-ray spectrometry with Peltier-cooled large area avalanche photodiodes

    International Nuclear Information System (INIS)

    Fernandes, L.M.P.; Lopes, J.A.M.; Santos, J.M.F. dos; Conde, C.A.N.

    2004-01-01

    Performance characteristics of the response of a Peltier-cooled large-area avalanche photodiode are investigated. Detector gain, energy linearity, energy resolution and minimum detectable energy are studied at different operation temperatures. Detector energy resolution and lowest detectable X-ray energy present a strong improvement as the operation temperature is reduced from 25 to 15 deg. C and slower improvements are achieved for temperatures below 10 deg. C

  13. The European Large Area ISO Survey - IV. The preliminary 90-mu m luminosity function

    DEFF Research Database (Denmark)

    Serjeant, S.; Efstathiou, A.; Oliver, S.

    2001-01-01

    We present the luminosity function of 90-mum-selected galaxies from the European Large Area ISO Survey (ELAIS), extending to z = 0.3. Their luminosities are in the range 10(9)

  14. Development of a large-area Multigap RPC with adequate spatial resolution for muon tomography

    Science.gov (United States)

    Wang, J.; Wang, Y.; Wang, X.; Zeng, M.; Xie, B.; Han, D.; Lyu, P.; Wang, F.; Li, Y.

    2016-11-01

    We study the performance of a large-area 2-D Multigap Resistive Plate Chamber (MRPC) designed for muon tomography with high spatial resolution. An efficiency up to 98% and a spatial resolution of around 270 μ m are obtained in cosmic ray and X-ray tests. The performance of the MRPC is also investigated for two working gases: standard gas and pure Freon. The result shows that the MRPC working in pure Freon can provide higher efficiency and better spatial resolution.

  15. Implications of Harvest on the Boundaries of Protected Areas for Large Carnivore Viewing Opportunities.

    Directory of Open Access Journals (Sweden)

    Bridget L Borg

    Full Text Available The desire to see free ranging large carnivores in their natural habitat is a driver of tourism in protected areas around the globe. However, large carnivores are wide-ranging and subject to human-caused mortality outside protected area boundaries. The impact of harvest (trapping or hunting on wildlife viewing opportunities has been the subject of intense debate and speculation, but quantitative analyses have been lacking. We examined the effect of legal harvest of wolves (Canis lupus along the boundaries of two North American National Parks, Denali (DNPP and Yellowstone (YNP, on wolf viewing opportunities within the parks during peak tourist season. We used data on wolf sightings, pack sizes, den site locations, and harvest adjacent to DNPP from 1997-2013 and YNP from 2008-2013 to evaluate the relationship between harvest and wolf viewing opportunities. Although sightings were largely driven by wolf population size and proximity of den sites to roads, sightings in both parks were significantly reduced by harvest. Sightings in YNP increased by 45% following years with no harvest of a wolf from a pack, and sightings in DNPP were more than twice as likely during a period with a harvest buffer zone than in years without the buffer. These findings show that harvest of wolves adjacent to protected areas can reduce sightings within those areas despite minimal impacts on the size of protected wolf populations. Consumptive use of carnivores adjacent to protected areas may therefore reduce their potential for non-consumptive use, and these tradeoffs should be considered when developing regional wildlife management policies.

  16. Implications of Harvest on the Boundaries of Protected Areas for Large Carnivore Viewing Opportunities.

    Science.gov (United States)

    Borg, Bridget L; Arthur, Stephen M; Bromen, Nicholas A; Cassidy, Kira A; McIntyre, Rick; Smith, Douglas W; Prugh, Laura R

    2016-01-01

    The desire to see free ranging large carnivores in their natural habitat is a driver of tourism in protected areas around the globe. However, large carnivores are wide-ranging and subject to human-caused mortality outside protected area boundaries. The impact of harvest (trapping or hunting) on wildlife viewing opportunities has been the subject of intense debate and speculation, but quantitative analyses have been lacking. We examined the effect of legal harvest of wolves (Canis lupus) along the boundaries of two North American National Parks, Denali (DNPP) and Yellowstone (YNP), on wolf viewing opportunities within the parks during peak tourist season. We used data on wolf sightings, pack sizes, den site locations, and harvest adjacent to DNPP from 1997-2013 and YNP from 2008-2013 to evaluate the relationship between harvest and wolf viewing opportunities. Although sightings were largely driven by wolf population size and proximity of den sites to roads, sightings in both parks were significantly reduced by harvest. Sightings in YNP increased by 45% following years with no harvest of a wolf from a pack, and sightings in DNPP were more than twice as likely during a period with a harvest buffer zone than in years without the buffer. These findings show that harvest of wolves adjacent to protected areas can reduce sightings within those areas despite minimal impacts on the size of protected wolf populations. Consumptive use of carnivores adjacent to protected areas may therefore reduce their potential for non-consumptive use, and these tradeoffs should be considered when developing regional wildlife management policies.

  17. ITO with embedded silver grids as transparent conductive electrodes for large area organic solar cells

    Science.gov (United States)

    Patil, Bhushan R.; Mirsafaei, Mina; Piotr Cielecki, Paweł; Fernandes Cauduro, André Luis; Fiutowski, Jacek; Rubahn, Horst-Günter; Madsen, Morten

    2017-10-01

    In this work, development of semi-transparent electrodes for efficient large area organic solar cells (OSCs) has been demonstrated. Electron beam evaporated silver grids were embedded in commercially available ITO coatings on glass, through a standard negative photolithography process, in order to improve the conductivity of planar ITO substrates. The fabricated electrodes with embedded line and square patterned Ag grids reduced the sheet resistance of ITO by 25% and 40%, respectively, showing optical transmittance drops of less than 6% within the complete visible light spectrum for both patterns. Solution processed bulk heterojunction OSCs based on PTB7:[70]PCBM were fabricated on top of these electrodes with cell areas of 4.38 cm2, and the performance of these OSCs was compared to reference cells fabricated on pure ITO electrodes. The Fill Factor (FF) of the large-scale OSCs fabricated on ITO with embedded Ag grids was enhanced by 18% for the line grids pattern and 30% for the square grids pattern compared to that of the reference OSCs. The increase in the FF was directly correlated to the decrease in the series resistance of the OSCs. The maximum power conversion efficiency (PCE) of the OSCs was measured to be 4.34%, which is 23% higher than the PCE of the reference OSCs. As the presented method does not involve high temperature processing, it could be considered a general approach for development of large area organic electronics on solvent resistant, flexible substrates.

  18. Large-area super-resolution optical imaging by using core-shell microfibers

    Science.gov (United States)

    Liu, Cheng-Yang; Lo, Wei-Chieh

    2017-09-01

    We first numerically and experimentally report large-area super-resolution optical imaging achieved by using core-shell microfibers. The particular spatial electromagnetic waves for different core-shell microfibers are studied by using finite-difference time-domain and ray tracing calculations. The focusing properties of photonic nanojets are evaluated in terms of intensity profile and full width at half-maximum along propagation and transversal directions. In experiment, the general optical fiber is chemically etched down to 6 μm diameter and coated with different metallic thin films by using glancing angle deposition. The direct imaging of photonic nanojets for different core-shell microfibers is performed with a scanning optical microscope system. We show that the intensity distribution of a photonic nanojet is highly related to the metallic shell due to the surface plasmon polaritons. Furthermore, large-area super-resolution optical imaging is performed by using different core-shell microfibers placed over the nano-scale grating with 150 nm line width. The core-shell microfiber-assisted imaging is achieved with super-resolution and hundreds of times the field-of-view in contrast to microspheres. The possible applications of these core-shell optical microfibers include real-time large-area micro-fluidics and nano-structure inspections.

  19. Rapid fabrication of large-area, corrosion-resistant superhydrophobic Mg alloy surfaces.

    Science.gov (United States)

    Xu, Wenji; Song, Jinlong; Sun, Jing; Lu, Yao; Yu, Ziyuan

    2011-11-01

    A superhydrophobic magnesium (Mg) alloy surface was successfully fabricated via a facile electrochemical machining process, and subsequently covered with a fluoroalkylsilane (FAS) film. The surface morphologies and chemical compositions were investigated using a scanning electron microscope (SEM) equipped with an energy-dispersive spectroscopy (EDS) and a Fourier-transform infrared spectrophotometer (FTIR). The results show hierarchal rough structures and an FAS film with a low surface energy on the Mg alloy surfaces, which confers good superhydrophobicity with a water contact angle of 165.2° and a water tilting angle of approximately 2°. The processing conditions, such as the processing time and removal rate per unit area at a constant removal mass per unit area, were investigated to determine their effects on the superhydrophobicity. Interestingly, when the removal mass per unit area is constant at approximately 11.10 mg/cm(2), the superhydrophobicity does not change with the removal rate per unit area. Therefore, a superhydrophobic Mg alloy surface can be rapidly fabricated based on this property. A large-area superhydrophobic Mg alloy surface was also fabricated for the first time using a small-area moving cathode. The corrosion resistance and durability of the superhydrophobic surfaces were also examined.

  20. [Effects of large-area planting water hyacinth on macro-benthos community structure and biomass].

    Science.gov (United States)

    Liu, Guo-Feng; Liu, Hai-Qin; Zhang, Zhi-Yong; Zhang, Ying-Ying; Yan, Shao-Hua; Zhong, Ji-Cheng; Fan, Cheng-Xin

    2010-12-01

    The effects on macro-benthos and benthos environment of planting 200 hm2 water hyacinth (E. crassipens) in Zhushan Bay, Lake Taihu, were studied during 8-10 months consecutive surveys. Results indicated that average densities of mollusca (the main species were Bellamya aeruginosa) in far-planting, near-planting and planting area were 276.67, 371.11 and 440.00 ind/m2, respectively, and biomass were 373.15, 486.57 and 672.54 g/m2, respectively, showed that average density and biomass of planting area's were higher than those of others. However, the average density and biomass of Oligochaeta (the main species was Limodrilus hoffmeisteri) and Chironomidae in planting area were lower than that of outside planting area. The density and biomass of three dominant species of benthic animal increased quickly during 8-9 months, decreased quickly in October inside and outside water hyacinth planting area. The reason of this phenomenon could be possible that lots of cyanobacteria cells died and consumed dissolve oxygen in proceed decomposing. Algae cells released lots of phosphorus and nitrogen simultaneously, so macro-benthos died in this environment. The indexes of Shannon-Weaver and Simpson indicated that water environment was in moderate polluted state. On the basis of the survey results, the large-area and high-density planting water hyacinth haven't demonstrated a great impact on macrobenthos and benthos environment in short planting time (about 6 months planting time).

  1. Analysis on Dangerous Source of Large Safety Accident in Storage Tank Area

    Science.gov (United States)

    Wang, Tong; Li, Ying; Xie, Tiansheng; Liu, Yu; Zhu, Xueyuan

    2018-01-01

    The difference between a large safety accident and a general accident is that the consequences of a large safety accident are particularly serious. To study the tank area which factors directly or indirectly lead to the occurrence of large-sized safety accidents. According to the three kinds of hazard source theory and the consequence cause analysis of the super safety accident, this paper analyzes the dangerous source of the super safety accident in the tank area from four aspects, such as energy source, large-sized safety accident reason, management missing, environmental impact Based on the analysis of three kinds of hazard sources and environmental analysis to derive the main risk factors and the AHP evaluation model is established, and after rigorous and scientific calculation, the weights of the related factors in four kinds of risk factors and each type of risk factors are obtained. The result of analytic hierarchy process shows that management reasons is the most important one, and then the environmental factors and the direct cause and Energy source. It should be noted that although the direct cause is relatively low overall importance, the direct cause of Failure of emergency measures and Failure of prevention and control facilities in greater weight.

  2. Research progress on large-area perovskite thin films and solar modules

    Directory of Open Access Journals (Sweden)

    Zhichun Yang

    2017-12-01

    Full Text Available Organometal halide perovskites have exhibited a bright future as photovoltaic semiconductor in next generation solar cells due to their unique and promising physicochemical properties. Over the past few years, we have witnessed a tremendous progress of efficiency record evolution of perovskite solar cells (PSCs. Up to now, the highest efficiency record of PSCs has reached 22.1%; however, it was achieved at a very small device area of <0.1 cm2. With the device area increasing to mini-module scale, the efficiency record dropped dramatically. The inherent causes are mainly ascribed to inadequate quality control of large-area perovskite thin films and insufficient optimization of solar module design. In current stage of PSCs research and development, to overcome these two obstacles is in urgent need before this new technology could realize scale-up industrialization. Herein, we present an overview of recently developed strategies for preparing large-area perovskite thin films and perovskite solar modules (PSMs. At last, cost analysis and future application directions of PSMs have also been discussed.

  3. Self-alignment of a compact large-area atomic Sagnac interferometer

    International Nuclear Information System (INIS)

    Tackmann, G; Berg, P; Schubert, C; Abend, S; Gilowski, M; Ertmer, W; Rasel, E M

    2012-01-01

    We report on the realization of a compact atomic Mach-Zehnder-type Sagnac interferometer of 13.7 cm length, which covers an area of 19 mm 2 previously reported only for large thermal beam interferometers. According to Sagnac's formula, which holds for both light and atoms, the sensitivity for rotation rates increases linearly with the area enclosed by the interferometer. The use of cold atoms instead of thermal atoms enables miniaturization of Sagnac interferometers without sacrificing large areas. In comparison with thermal beams, slow atoms offer better matching of the initial beam velocity and the velocity with which the matter waves separate. In our case, the area is spanned by a cold atomic beam of 2.79 m s -1 , which is split, deflected and combined by driving a Raman transition between the two hyperfine ground states of 87 Rb in three spatially separated light zones. The use of cold atoms requires a precise angular alignment and high wave front quality of the three independent light zones over the cloud envelope. We present a procedure for mutually aligning the beam splitters at the microradian level by making use of the atom interferometer itself in different configurations. With this method, we currently achieve a sensitivity of 6.1×10 -7 rad s -1 Hz -1/2 . (paper)

  4. Evaluation of bacterial nanocellulose-based uniform wound dressing for large area skin transplantation

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Lina [Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); National Engineering Research Center for Nano-Medicine, Huazhong University of Science and Technology, Wuhan 430074 (China); Zhou, Ping [Institute of Organ Transplant of Tongji Hospital, Huazhong University of Science and Technology, Wuhan (China); Zhang, Shengmin [Advanced Biomaterials and Tissue Engineering Center, Huazhong University of Science and Technology, Wuhan (China); Yang, Guang, E-mail: yang_sunny@yahoo.com [Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); National Engineering Research Center for Nano-Medicine, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2013-07-01

    Bacterial nanocellulose (BNC) was biosynthesized by Gluconacetobacter xylinus. The surface area, physicochemical structure and morphology of the materials were characterized. Here provides a method for an efficient production of uniform BNC, which is beneficial for the fast characterization and evaluation of BNC. In vitro cytotoxicity of the materials was evaluated by the proliferation, the adhesion, the viability and the morphology of NIH/3T3 cells. Low cytotoxicity of the BNC was observed, and micrographs demonstrate a good proliferation and adhesion of NIH/3T3 cells on BNC. Large area full-thickness skin defects were made on the back of C57BL/6 mice in animal surgery. The wounds were transplanted with BNC films and the results compared to those in a control group. The rehabilitation of the wound surfaces and the pathological sections of mice were investigated and are discussed. Histological examinations demonstrated faster and better healing effect and lower inflammatory response in the BNC group than those in the control group. Preliminary results on wound dressings from BNC show a curative effect promoting the healing of epithelial tissue. BNC is a promising natural polymer with medical applications in wound dressings. - Highlights: • BNC is expected to be a promising material in wound healing and skin transplantation. • We studied surface area, physicochemical structures and morphology of uniform BNC. • Cyto-evaluation results of BNC-based wound dressing show a good biocompatibility. • Large area skin transplantation experiments suggest a good performance of healing.

  5. Evaluation of bacterial nanocellulose-based uniform wound dressing for large area skin transplantation

    International Nuclear Information System (INIS)

    Fu, Lina; Zhou, Ping; Zhang, Shengmin; Yang, Guang

    2013-01-01

    Bacterial nanocellulose (BNC) was biosynthesized by Gluconacetobacter xylinus. The surface area, physicochemical structure and morphology of the materials were characterized. Here provides a method for an efficient production of uniform BNC, which is beneficial for the fast characterization and evaluation of BNC. In vitro cytotoxicity of the materials was evaluated by the proliferation, the adhesion, the viability and the morphology of NIH/3T3 cells. Low cytotoxicity of the BNC was observed, and micrographs demonstrate a good proliferation and adhesion of NIH/3T3 cells on BNC. Large area full-thickness skin defects were made on the back of C57BL/6 mice in animal surgery. The wounds were transplanted with BNC films and the results compared to those in a control group. The rehabilitation of the wound surfaces and the pathological sections of mice were investigated and are discussed. Histological examinations demonstrated faster and better healing effect and lower inflammatory response in the BNC group than those in the control group. Preliminary results on wound dressings from BNC show a curative effect promoting the healing of epithelial tissue. BNC is a promising natural polymer with medical applications in wound dressings. - Highlights: • BNC is expected to be a promising material in wound healing and skin transplantation. • We studied surface area, physicochemical structures and morphology of uniform BNC. • Cyto-evaluation results of BNC-based wound dressing show a good biocompatibility. • Large area skin transplantation experiments suggest a good performance of healing

  6. Large area, low capacitance, GaAs nanowire photodetector with a transparent Schottky collecting junction

    Energy Technology Data Exchange (ETDEWEB)

    Seyedi, M. A., E-mail: seyedi@usc.edu; Yao, M.; O' Brien, J.; Dapkus, P. D. [Center for Energy Nanoscience, University of Southern California, Los Angeles, California 90089 (United States); Wang, S. Y. [Center for Energy Nanoscience, University of Southern California, Los Angeles, California 90089 (United States); Nanostructured Energy Conversion Technology and Research (NECTAR), Advanced Studies Laboratories, University of California, Santa Cruz, California 95064, USA and NASA Ames Research Center, Moffett Field, California 94035 (United States)

    2013-12-16

    We present experimental results on a GaAs/Indium-Tin-Oxide Schottky-like heterojunction photodetector based on a nanowire device geometry. By distributing the active detecting area over an array of nanowires, it is possible to achieve large area detection with low capacitance. Devices with bare GaAs and passivated AlGaAs/GaAs nanowires are fabricated to compare the responsivity with and without surface passivation. We are able to achieve responsivity of >0.5A/W and Signal-Noise-Ratio in excess of 7 dB for 2 V applied reverse bias with passivated nanowire devices. Capacitance-voltage measurement yields <5 nF/cm{sup 2}, which shows a strong possibility for high-speed applications with a broad area device.

  7. Large area, low capacitance, GaAs nanowire photodetector with a transparent Schottky collecting junction

    International Nuclear Information System (INIS)

    Seyedi, M. A.; Yao, M.; O'Brien, J.; Dapkus, P. D.; Wang, S. Y.

    2013-01-01

    We present experimental results on a GaAs/Indium-Tin-Oxide Schottky-like heterojunction photodetector based on a nanowire device geometry. By distributing the active detecting area over an array of nanowires, it is possible to achieve large area detection with low capacitance. Devices with bare GaAs and passivated AlGaAs/GaAs nanowires are fabricated to compare the responsivity with and without surface passivation. We are able to achieve responsivity of >0.5A/W and Signal-Noise-Ratio in excess of 7 dB for 2 V applied reverse bias with passivated nanowire devices. Capacitance-voltage measurement yields 2 , which shows a strong possibility for high-speed applications with a broad area device

  8. Fabrication of Large Area Fishnet Optical Metamaterial Structures Operational at Near-IR Wavelengths

    Directory of Open Access Journals (Sweden)

    Dennis W. Prather

    2010-12-01

    Full Text Available In this paper, we demonstrate a fabrication process for large area (2 mm × 2 mm fishnet metamaterial structures for near IR wavelengths. This process involves: (a defining a sacrificial Si template structure onto a quartz wafer using deep-UV lithography and a dry etching process (b deposition of a stack of Au-SiO2-Au layers and (c a ‘lift-off’ process which removes the sacrificial template structure to yield the fishnet structure. The fabrication steps in this process are compatible with today’s CMOS technology making it eminently well suited for batch fabrication. Also, depending on area of the exposure mask available for patterning the template structure, this fabrication process can potentially lead to optical metamaterials spanning across wafer-size areas.

  9. Two-group interfacial area concentration correlations of two-phase flows in large diameter pipes

    International Nuclear Information System (INIS)

    Shen, Xiuzhong; Hibiki, Takashi

    2015-01-01

    The reliable empirical correlations and models are one of the important ways to predict the interfacial area concentration (IAC) in two-phase flows. However, up to now, no correlation or model is available for the prediction of the IAC in the two-phase flows in large diameter pipes. This study collected an IAC experimental database of two-phase flows taken under various flow conditions in large diameter pipes and presented a systematic way to predict the IAC for two-phase flows from bubbly, cap-bubbly to churn flow in large diameter pipes by categorizing bubbles into two groups (group-1: spherical and distorted bubble, group-2: cap bubble). Correlations were developed to predict the group-1 void fraction from the void fraction of all bubble. The IAC contribution from group-1 bubbles was modeled by using the dominant parameters of group-1 bubble void fraction and Reynolds number based on the parameter-dependent analysis of Hibiki and Ishii (2001, 2002) using one-dimensional bubble number density and interfacial area transport equations. A new drift velocity correlation for two-phase flow with large cap bubbles in large diameter pipes was derived in this study. By comparing the newly-derived drift velocity correlation with the existing drift velocity correlation of Kataoka and Ishii (1987) for large diameter pipes and using the characteristics of the representative bubbles among the group 2 bubbles, we developed the model of IAC and bubble size for group 2 cap bubbles. The developed models for estimating the IAC are compared with the entire collected database. A reasonable agreement was obtained with average relative errors of ±28.1%, ±54.4% and ±29.6% for group 1, group 2 and all bubbles respectively. (author)

  10. Optimized preparation for large surface area activated carbon from date (Phoenix dactylifera L.) stone biomass

    International Nuclear Information System (INIS)

    Danish, Mohammed; Hashim, Rokiah; Ibrahim, M.N. Mohamad; Sulaiman, Othman

    2014-01-01

    The preparation of activated carbon from date stone treated with phosphoric acid was optimized using rotatable central composite design of response surface methodology (RSM). The chemical activating agent concentration and temperature of activation plays a crucial role in preparation of large surface area activated carbons. The optimized activated carbon was characterized using thermogravimetric analysis, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, powder X-ray diffraction, and Fourier transform infrared spectroscopy. The results showed that the larger surface area of activated carbon from date stone can be achieved under optimum activating agent (phosphoric acid) concentration, 50.0% (8.674 mol L −1 ) and activation temperature, 900 °C. The Brunauer–Emmett–Teller (BET) surface area of optimized activated carbon was found to be 1225 m 2  g −1 , and thermogravimetric analysis revealed that 55.2% mass of optimized activated carbon was found thermally stable till 900 °C. The leading chemical functional groups found in the date stone activated carbon were aliphatic carboxylic acid salt ν(C=O) 1561.22 cm −1 and 1384.52 cm −1 , aliphatic hydrocarbons ν(C–H) 2922.99 cm −1 (C–H sym./asym. stretch frequency), aliphatic phosphates ν(P–O–C) 1054.09 cm −1 , and secondary aliphatic alcohols ν(O–H) 3419.81 cm −1 and 1159.83 cm −1 . - Highlights: • RSM optimization was done for the production of large surface area activated carbon. • Two independent variables with two responses were selected for optimization. • Characterization was done for surface area, morphology and chemical constituents. • Optimized date stone activated carbon achieved surface area 1225 m 2  g −1

  11. Interfacial area concentration in gas–liquid bubbly to churn flow regimes in large diameter pipes

    International Nuclear Information System (INIS)

    Shen, Xiuzhong; Hibiki, Takashi

    2015-01-01

    Highlights: • A systematic method to predict interfacial area concentration (IAC) is presented. • A correlation for group 1 bubble void fraction is proposed. • Correlations of IAC and bubble diameter are developed for group 1 bubbles. • Correlations of IAC and bubble diameter are developed for group 2 bubbles. • The newly-developed two-group IAC model compares well with collected databases. - Abstract: This study performed a survey on existing correlations for interfacial area concentration (IAC) prediction and collected an IAC experimental database of two-phase flows taken under various flow conditions in large diameter pipes. Although some of these existing correlations were developed by partly using the IAC databases taken in the low-void-fraction two-phase flows in large diameter pipes, no correlation can satisfactorily predict the IAC in the two-phase flows changing from bubbly, cap bubbly to churn flow in the collected database of large diameter pipes. So this study presented a systematic way to predict the IAC for the bubbly-to-churn flows in large diameter pipes by categorizing bubbles into two groups (group 1: spherical or distorted bubble, group 2: cap bubble). A correlation was developed to predict the group 1 void fraction by using the void fraction for all bubble. The group 1 bubble IAC and bubble diameter were modeled by using the key parameters such as group 1 void fraction and bubble Reynolds number based on the analysis of Hibiki and Ishii (2001, 2002) using one-dimensional bubble number density and interfacial area transport equations. The correlations of IAC and bubble diameter for group 2 cap bubbles were developed by taking into account the characteristics of the representative bubbles among the group 2 bubbles and the comparison between a newly-derived drift velocity correlation for large diameter pipes and the existing drift velocity correlation of Kataoka and Ishii (1987) for large diameter pipes. The predictions from the newly

  12. A small-scale, rolled-membrane microfluidic artificial lung designed towards future large area manufacturing.

    Science.gov (United States)

    Thompson, A J; Marks, L H; Goudie, M J; Rojas-Pena, A; Handa, H; Potkay, J A

    2017-03-01

    Artificial lungs have been used in the clinic for multiple decades to supplement patient pulmonary function. Recently, small-scale microfluidic artificial lungs (μAL) have been demonstrated with large surface area to blood volume ratios, biomimetic blood flow paths, and pressure drops compatible with pumpless operation. Initial small-scale microfluidic devices with blood flow rates in the μ l/min to ml/min range have exhibited excellent gas transfer efficiencies; however, current manufacturing techniques may not be suitable for scaling up to human applications. Here, we present a new manufacturing technology for a microfluidic artificial lung in which the structure is assembled via a continuous "rolling" and bonding procedure from a single, patterned layer of polydimethyl siloxane (PDMS). This method is demonstrated in a small-scale four-layer device, but is expected to easily scale to larger area devices. The presented devices have a biomimetic branching blood flow network, 10  μ m tall artificial capillaries, and a 66  μ m thick gas transfer membrane. Gas transfer efficiency in blood was evaluated over a range of blood flow rates (0.1-1.25 ml/min) for two different sweep gases (pure O 2 , atmospheric air). The achieved gas transfer data closely follow predicted theoretical values for oxygenation and CO 2 removal, while pressure drop is marginally higher than predicted. This work is the first step in developing a scalable method for creating large area microfluidic artificial lungs. Although designed for microfluidic artificial lungs, the presented technique is expected to result in the first manufacturing method capable of simply and easily creating large area microfluidic devices from PDMS.

  13. Organic solar cell modules for specific applications-From energy autonomous systems to large area photovoltaics

    International Nuclear Information System (INIS)

    Niggemann, M.; Zimmermann, B.; Haschke, J.; Glatthaar, M.; Gombert, A.

    2008-01-01

    We report on the development of two types of organic solar cell modules one for energy autonomous systems and one for large area energy harvesting. The first requires a specific tailoring of the solar cell geometry and cell interconnection in order to power an energy autonomous system under its specific operating conditions. We present an organic solar cell module with 22 interconnected solar cells. A power conversion efficiency of 2% under solar illumination has been reached on the active area of 46.2 cm 2 . A voltage of 4 V at the maximum power point has been obtained under indoor illumination conditions. Micro contact printing of a self assembling monolayer was employed for the patterning of the polymer anode. Large area photovoltaic modules have to meet the requirements on efficiency, lifetime and costs simultaneously. To minimize the production costs, a suitable concept for efficient reel-to-reel production of large area modules is needed. A major contribution to reduce the costs is the substitution of the commonly used indium tin oxide electrode by a cheap material. We present the state of the art of the anode wrap through concept as a reel-to-reel suited module concept and show comparative calculations of the module interconnection of the wrap through concept and the standard ITO-based cell architecture. As a result, the calculated overall module efficiency of the anode wrap through module exceeds the overall efficiency of modules based on ITO on glass (sheet resistance 15 Ω/square) and on foils (sheet resistance 60 Ω/square)

  14. Interpretation of the peak areas in gamma-ray spectra that have a large relative uncertainty

    International Nuclear Information System (INIS)

    Korun, M.; Maver Modec, P.; Vodenik, B.

    2012-01-01

    Empirical evidence is provided that the areas of peaks having a relative uncertainty in excess of 30% are overestimated. This systematic influence is of a statistical nature and originates in way the peak-analyzing routine recognizes the small peaks. It is not easy to detect this influence since it is smaller than the peak-area uncertainty. However, the systematic influence can be revealed in repeated measurements under the same experimental conditions, e.g., in background measurements. To evaluate the systematic influence, background measurements were analyzed with the peak-analyzing procedure described by Korun et al. (2008). The magnitude of the influence depends on the relative uncertainty of the peak area and may amount, in the conditions used in the peak analysis, to a factor of 5 at relative uncertainties exceeding 60%. From the measurements, the probability for type-II errors, as a function of the relative uncertainty of the peak area, was extracted. This probability is near zero below an uncertainty of 30% and rises to 90% at uncertainties exceeding 50%. - Highlights: ► A systematic influence affecting small peak areas in gamma-ray spectra is described. ► The influence originates in the peak locating procedure, using a pre-determined sensitivity. ► The predetermined sensitivity makes peak areas with large uncertainties to be overestimated. ► The influence depends on the relative uncertainty of the number of counts in the peak. ► Corrections exceeding a factor of 3 are attained at peak area uncertainties exceeding 60%.

  15. Thin absorbers for large-area soft X-ray microcalorimeters

    Energy Technology Data Exchange (ETDEWEB)

    Rocks, L. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States)]. E-mail: rocks@wisp.physics.wisc.edu; Anderson, M.B. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Bilgri, N. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Brekosky, R. [NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Gwynne Crowder, S. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Figueroa-Feliciano, E. [NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Kelley, R. [NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Kilbourne, C.A. [NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Lai, T. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Lindeman, M.A. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Man, J. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); McCammon, D. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Nelms, K.L. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Porter, F.S. [NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Sivananthan, S. [University of Illinois at Chicago, Chicago, IL 60607 (United States); Vidugiris, G. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Zhao, J. [University of Illinois at Chicago, Chicago, IL 60607 (United States)

    2006-04-15

    The X-ray Quantum Calorimeter (XQC) sounding rocket experiment utilizes a microcalorimeter array for observing the diffuse soft X-ray background. Observations of such low surface-brightness targets require a large-area detector. We will be using an array of large absorbers. Good absorbers must rapidly and completely thermalize photons, have small heat capacity for high stopping efficiency and have good lateral thermal transport. For observing the soft X-ray background (energies <1 keV), the volume and heat capacity of absorber material can be kept to a minimum by making the absorbers only as thick as needed for high quantum efficiency at these low energies. These thin, large-area absorbers are not self-supporting and have poor lateral heat transport. Depositing the absorber material on a Si substrate provides support and improves lateral thermal conduction. We present heat capacity results for thin HgTe and thin Bi, each on Si substrates. We also describe the HgTe absorber fabrication.

  16. Wettability Investigations and Wet Transfer Enhancement of Large-Area CVD-Graphene on Aluminum Nitride.

    Science.gov (United States)

    Knapp, Marius; Hoffmann, René; Cimalla, Volker; Ambacher, Oliver

    2017-08-18

    The two-dimensional and virtually massless character of graphene attracts great interest for radio frequency devices, such as surface and bulk acoustic wave resonators. Due to its good electric conductivity, graphene might be an alternative as a virtually massless electrode by improving resonator performance regarding mass-loading effects . We report on an optimization of the commonly used wet transfer technique for large-area graphene, grown via chemical vapor deposition, onto aluminum nitride (AlN), which is mainly used as an active, piezoelectric material for acoustic devices. Today, graphene wet transfer is well-engineered for silicon dioxide (SiO₂). Investigations on AlN substrates reveal highly different surface properties compared to SiO₂ regarding wettability, which strongly influences the quality of transferred graphene monolayers. Both physical and chemical effects of a plasma treatment of AlN surfaces change wettability and avoid large-scale cracks in the transferred graphene sheet during desiccation. Spatially-resolved Raman spectroscopy reveals a strong strain and doping dependence on AlN plasma pretreatments correlating with the electrical conductivity of graphene. In our work, we achieved transferred crack-free large-area (40 × 40 mm²) graphene monolayers with sheet resistances down to 350 Ω/sq. These achievements make graphene more powerful as an eco-friendly and cheaper replacement for conventional electrode materials used in radio frequency resonator devices.

  17. Enhancing Performance of Large-Area Organic Solar Cells with Thick Film via Ternary Strategy.

    Science.gov (United States)

    Zhang, Jianqi; Zhao, Yifan; Fang, Jin; Yuan, Liu; Xia, Benzheng; Wang, Guodong; Wang, Zaiyu; Zhang, Yajie; Ma, Wei; Yan, Wei; Su, Wenming; Wei, Zhixiang

    2017-06-01

    Large-scale fabrication of organic solar cells requires an active layer with high thickness tolerability and the use of environment-friendly solvents. Thick films with high-performance can be achieved via a ternary strategy studied herein. The ternary system consists of one polymer donor, one small molecule donor, and one fullerene acceptor. The small molecule enhances the crystallinity and face-on orientation of the active layer, leading to improved thickness tolerability compared with that of a polymer-fullerene binary system. An active layer with 270 nm thickness exhibits an average power conversion efficiency (PCE) of 10.78%, while the PCE is less than 8% with such thick film for binary system. Furthermore, large-area devices are successfully fabricated using polyethylene terephthalate (PET)/Silver gride or indium tin oxide (ITO)-based transparent flexible substrates. The product shows a high PCE of 8.28% with an area of 1.25 cm 2 for a single cell and 5.18% for a 20 cm 2 module. This study demonstrates that ternary organic solar cells exhibit great potential for large-scale fabrication and future applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Efficient transfer of large-area graphene films onto rigid substrates by hot pressing.

    Science.gov (United States)

    Kang, Junmo; Hwang, Soonhwi; Kim, Jae Hwan; Kim, Min Hyeok; Ryu, Jaechul; Seo, Sang Jae; Hong, Byung Hee; Kim, Moon Ki; Choi, Jae-Boong

    2012-06-26

    Graphene films grown on metal substrates by chemical vapor deposition (CVD) method have to be safely transferred onto desired substrates for further applications. Recently, a roll-to-roll (R2R) method has been developed for large-area transfer, which is particularly efficient for flexible target substrates. However, in the case of rigid substrates such as glass or wafers, the roll-based method is found to induce considerable mechanical damages on graphene films during the transfer process, resulting in the degradation of electrical property. Here we introduce an improved dry transfer technique based on a hot-pressing method that can minimize damage on graphene by neutralizing mechanical stress. Thus, we enhanced the transfer efficiency of the large-area graphene films on a substrate with arbitrary thickness and rigidity, evidenced by scanning electron microscope (SEM) and atomic force microscope (AFM) images, Raman spectra, and various electrical characterizations. We also performed a theoretical multiscale simulation from continuum to atomic level to compare the mechanical stresses caused by the R2R and the hot-pressing methods, which also supports our conclusion. Consequently, we believe that the proposed hot-pressing method will be immediately useful for display and solar cell applications that currently require rigid and large substrates.

  19. Development of large-area high-temperature fixed-point blackbodies for photometry and radiometry

    Science.gov (United States)

    Khlevnoy, Boris; Grigoryeva, Irina; Anhalt, Klaus; Waehmer, Martin; Ivashin, Evgeniy; Otryaskin, Denis; Solodilov, Maxim; Sapritsky, Victor

    2018-04-01

    Large-area high-temperature fixed-point (HTFP) blackbodies with working temperatures of approximately 2748 K and 3021 K, based on an Re-C eutectic and a WC-C peritectic respectively, have been developed and investigated. The blackbodies have an emissivity of 0.9997, show high-quality phase-transition plateaus and have high repeatability of the melting temperatures, but demonstrate temperature differences (from 0.2 K to 0.6 K) compared with small-cell blackbodies of the same HTFP. We associate these temperature differences with the temperature drop effect, which may differ from cell to cell. The large radiating cavity diameter of 14 mm allows developed HTFP blackbodies to be used for photometric and radiometric applications in irradiance mode with uncertainties as small as 0.12% (k  =  1) in the visible. A photometer and an irradiance-mode filter radiometer (visible range), previously calibrated at VNIIOFI, were used to measure illuminance and irradiance of the HTFP blackbodies equipped with a precise outer aperture. The values measured by the detectors agreed with those based on the blackbody calculation to within 0.2%. The large-area HTFP blackbodies will be used in a joint PTB-VNIIOFI experiment on measuring thermodynamic temperature.

  20. Towards Large-area Field-scale Operational Evapotranspiration for Water Use Mapping

    Science.gov (United States)

    Senay, G. B.; Friedrichs, M.; Morton, C.; Huntington, J. L.; Verdin, J.

    2017-12-01

    Field-scale evapotranspiration (ET) estimates are needed for improving surface and groundwater use and water budget studies. Ideally, field-scale ET estimates would be at regional to national levels and cover long time periods. As a result of large data storage and computational requirements associated with processing field-scale satellite imagery such as Landsat, numerous challenges remain to develop operational ET estimates over large areas for detailed water use and availability studies. However, the combination of new science, data availability, and cloud computing technology is enabling unprecedented capabilities for ET mapping. To demonstrate this capability, we used Google's Earth Engine cloud computing platform to create nationwide annual ET estimates with 30-meter resolution Landsat ( 16,000 images) and gridded weather data using the Operational Simplified Surface Energy Balance (SSEBop) model in support of the National Water Census, a USGS research program designed to build decision support capacity for water management agencies and other natural resource managers. By leveraging Google's Earth Engine Application Programming Interface (API) and developing software in a collaborative, open-platform environment, we rapidly advance from research towards applications for large-area field-scale ET mapping. Cloud computing of the Landsat image archive combined with other satellite, climate, and weather data, is creating never imagined opportunities for assessing ET model behavior and uncertainty, and ultimately providing the ability for more robust operational monitoring and assessment of water use at field-scales.

  1. Power Generation from a Radiative Thermal Source Using a Large-Area Infrared Rectenna

    Science.gov (United States)

    Shank, Joshua; Kadlec, Emil A.; Jarecki, Robert L.; Starbuck, Andrew; Howell, Stephen; Peters, David W.; Davids, Paul S.

    2018-05-01

    Electrical power generation from a moderate-temperature thermal source by means of direct conversion of infrared radiation is important and highly desirable for energy harvesting from waste heat and micropower applications. Here, we demonstrate direct rectified power generation from an unbiased large-area nanoantenna-coupled tunnel diode rectifier called a rectenna. Using a vacuum radiometric measurement technique with irradiation from a temperature-stabilized thermal source, a generated power density of 8 nW /cm2 is observed at a source temperature of 450 °C for the unbiased rectenna across an optimized load resistance. The optimized load resistance for the peak power generation for each temperature coincides with the tunnel diode resistance at zero bias and corresponds to the impedance matching condition for a rectifying antenna. Current-voltage measurements of a thermally illuminated large-area rectenna show current zero crossing shifts into the second quadrant indicating rectification. Photon-assisted tunneling in the unbiased rectenna is modeled as the mechanism for the large short-circuit photocurrents observed where the photon energy serves as an effective bias across the tunnel junction. The measured current and voltage across the load resistor as a function of the thermal source temperature represents direct current electrical power generation.

  2. Large area crystallization of amorphous Si with overlapping high repetition rate laser pulses

    KAUST Repository

    Ryu, Sang-Gil

    2012-09-01

    This paper presents a pulsed laser crystallization technique, enabling large area crystallization of amorphous Si to produce grains having well-defined size and orientation. The method is developed by first determining the parameters influencing crystallization induced by single laser pulses of circular cross-sectional profile. In a second step, crystallization by overlapping round spots is examined. The experiments reveal three zones characterized by distinctly different crystallized morphologies following the laser irradiation. One of these zones corresponds to the regime of lateral crystal growth, wherein grains are driven towards the center of the spot by the radial temperature gradient. These findings are then applied to processing via line beam profiles that facilitate large area crystallization upon rapid translation of the specimen. Crystallization of extended areas hinges on the determination of the crystal growth length for a single spot. The pitch between successive pulses is then set on the basis of this information. It is shown that the pulse energy has only a weak effect on the crystal growth length. © 2012 Elsevier B.V.

  3. Fabrication of a Horizontal and a Vertical Large Surface Area Nanogap Electrochemical Sensor

    Directory of Open Access Journals (Sweden)

    Jules L. Hammond

    2016-12-01

    Full Text Available Nanogap sensors have a wide range of applications as they can provide accurate direct detection of biomolecules through impedimetric or amperometric signals. Signal response from nanogap sensors is dependent on both the electrode spacing and surface area. However, creating large surface area nanogap sensors presents several challenges during fabrication. We show two different approaches to achieve both horizontal and vertical coplanar nanogap geometries. In the first method we use electron-beam lithography (EBL to pattern an 11 mm long serpentine nanogap (215 nm between two electrodes. For the second method we use inductively-coupled plasma (ICP reactive ion etching (RIE to create a channel in a silicon substrate, optically pattern a buried 1.0 mm × 1.5 mm electrode before anodically bonding a second identical electrode, patterned on glass, directly above. The devices have a wide range of applicability in different sensing techniques with the large area nanogaps presenting advantages over other devices of the same family. As a case study we explore the detection of peptide nucleic acid (PNA−DNA binding events using dielectric spectroscopy with the horizontal coplanar device.

  4. Pushing the boundaries of high power lasers: low loss, large area CVD diamond

    Science.gov (United States)

    Wickham, Benjamin; Schoofs, Frank; Olsson-Robbie, Stefan; Bennett, Andrew; Balmer, Richard

    2018-02-01

    Synthetic CVD diamond has exceptional properties, including broad spectral transmission, physical and chemical robustness, and the highest thermal conductivity of any known material, making diamond an attractive material for medium to high power optical and laser applications, minimizing the detrimental effects of thermal lensing and radiation damage. Example applications include ATR prisms, Raman laser crystals, extra- and intra-cavity laser cooling. In each case the demands on the fundamental material properties and fabrication routes are slightly different. In recent years, there has been good progress in the development of low-loss, single crystal diamond, suitable for higher power densities, higher pulse rates and more demanding intra- and extra-cavity thermal management. The adoption of single crystal diamond in this area has however, been hindered by the availability of large area, low birefringence plates. To address this, we report a combination of CVD growth and processing methods that have enabled the manufacture of large, low defect substrates. A final homoepitaxial, low absorption synthesis stage has produced plates with large area (up to 16 mm edge length), low absorption (α<0.005 cm-1 at 1064 nm), and low birefringence (Δn <10-5), suitable for double-sided intra-cavity cooling. We demonstrate the practical advances in synthesis, including increasing the size while reducing in-use losses compared to previous generations of single crystal material, and practical developments in processing and implementation of the single crystal diamond parts, optimizing them for use in a state-of-the-art femto-second pulsed Ti:Sa thin disk gain module, all made in collaboration with the wider European FP7 funded Ti:Sa TD consortium.

  5. Investigation on the growth of DAST crystals of large surface area for THz applications

    International Nuclear Information System (INIS)

    Vijay, R. Jerald; Melikechi, N.; Thomas, Tina; Gunaseelan, R.; Arockiaraj, M. Antony; Sagayaraj, P.

    2012-01-01

    Graphical abstract: It is evident from the photographs that the crystal tend to grow as a needle (Fig. 1a) in the lower concentration region (2–3 g/200 mL); whereas, in the high concentration region (5 g/200 mL) though there is a marked enlargement in the size of the crystal, the morphology of the resulting DAST crystal is slightly irregular (Fig. 1d) in nature. Among the four concentrations employed, best result was obtained with the DAST–methanol solution of concentration 4 g/200 mL; which resulted in the DAST crystal of large surface area (270 mm 2 ) with high transparency and nearly square shape (Fig. 1c) in a growth period of 20–25 days. Highlights: ► DAST crystals of different sizes are obtained for different concentrations. ► The main focus is to grow DAST crystals with large surface area. ► Structural, optical, thermal and mechanical properties are investigated. - Abstract: The growth of high quality 4-N,N-dimethylamino-4-N-methyl-stilbazoliumtosylate (DAST) crystal with large surface area is reported by adopting the slope nucleation coupled slow evaporation method (SNM-SE). The structure and composition of the crystal are studied by single crystal X-ray diffraction and CHN analyses. The linear optical properties are investigated by UV–vis absorption. The melting point and thermal behavior of DAST are investigated using differential scanning calorimetric (DSC) and thermogravimetric analyses (TGA). The Vickers microhardness number (VHN) and work hardening coefficient of the grown crystal have been determined. The surface features of the DAST crystal are analyzed by scanning electron microscopy (SEM) and it confirmed the presence of narrow line defects (NLDs) in the sample.

  6. Development of large area silicon semiconductor detectors for use in the current mode

    CERN Document Server

    Ouyang Xia Opin; Li Zhen Fu; Zhang Guo Guang; Zhang Qi; Zhang Xia; Song Xian Cai; Jia Huan Yi; Lei Jian Hua; Sun Yuan Cheng

    2002-01-01

    Large area silicon semiconductor detectors for use in the current mode, with their dimensions of phi 40, phi 50 and phi 60 mm, their depletion thickness of 200-300 mu m, have been developed. Their performance measurements have been made, which indicate that the developed detectors can satisfactorily meet the needs in expectation. Compared with the detectors commercially available on the market, authors' large PIN detectors can serve both as reliable and efficient high-resolution devices for nuclear counting experiments, as well as monitors of high-intensity radiation fields in the current mode under a bias of 100-1000 V, while the detectors commercially available are only for the counting use

  7. An advanced open-path atmospheric pollution monitor for large areas

    International Nuclear Information System (INIS)

    Taylor, L.

    1995-01-01

    Large amounts of toxic waste materials, generated in manufacturing fuel for nuclear reactors, are stored in tanks buried over large areas at DOE sites. Flammable and hazardous gases are continually generated by chemical reactions in the waste materials. To prevent explosive concentrations of these gases, the gases are automatically vented to the atmosphere when the pressure exceeds a preset value. Real-time monitoring of the atmosphere above the tanks with automatic alarming is needed to prevent exposing workers to unsafe conditions when venting occurs. This project is to design, develop, and test an atmospheric pollution monitor which can measure concentrations of DOE-specified and EPA-specified hazardous gases over ranges as long as 4km. A CO 2 laser to measure absorption spectra and to determine the distance over which the measurements are made, is combined with an acousto-optic tunable filter (AOTF) to measure thermal emission spectra

  8. Modeling thermo-optic effect in large mode area double cladding photonic crystal fibers

    Science.gov (United States)

    Coscelli, Enrico; Cucinotta, Annamaria

    2014-02-01

    The impact of thermally-induced refractive index changes on the single-mode (SM) properties of large mode area (LMA) photonic crystal fibers are thoroughly investigated by means of a full-vector modal solver with integrated thermal model. Three photonic crystal fiber designs are taken into account, namely the 19-cell core fiber, the large-pitch fiber (LPF) and the distributed modal filtering (DMF) fiber, to assess the effects of the interplay between thermal effects and the high-order mode (HOM) suppression mechanisms exploited in order to obtain effectively SM guiding. The results have shown significant differences in the way the SM regime is changed by the increase of heat load, providing useful hints for the design of LMA fibers for high power lasers.

  9. Replication fidelity assessment of large area sub-μm structured polymer surfaces using scatterometry

    International Nuclear Information System (INIS)

    Calaon, M; Hansen, H N; Tosello, G; Madsen, M H; Weirich, J; Hansen, P E; Garnaes, J; Tang, P T

    2015-01-01

    The present study addresses one of the key challenges in the product quality control of transparent structured polymer substrates, the replication fidelity of sub-μm structures over a large area. Additionally the work contributes to the development of new techniques focused on in-line characterization of large nanostructured surfaces using scatterometry. In particular an approach to quantify the replication fidelity of high volume manufacturing processes such as polymer injection moulding is presented. Both periodic channels and semi-spherical structures were fabricated on nickel shims used for later injection moulding of Cyclic-olefin-copolymer (COC) substrate were the sub-μm features where ultimately transferred. The scatterometry system was validated using calibrated atomic force microscopy measurements and a model based on scalar diffraction theory employed to calculate the expected angular distribution of the reflected and the transmitted intensity for the nickel surfaces and structured COC and, respectively. (paper)

  10. A gas proportional scintillation counter for use in large area detector systems without photomultipliers

    International Nuclear Information System (INIS)

    Baruch, J.E.F.; Brooke, G.; Kellermann, E.W.; Bateman, J.E.; Connolly, J.F.

    1978-03-01

    The properties of a prototype gas proportional scintillation detector, for use in large numbers, are examined. The detector is designed to focus a light signal, which is proportional to ionisation loss, into a fibre optic lightguide. It is shown that a single charged particle traversing the detector produces enough light out of the lightguide to be seen by a TV camera. Problems of lifetime and large scale detector production are discussed. Properties of saturation, linearity, position sensitivity, and operating limits are examined. It is shown that an array of gas proportional scintillation detectors when used with fibre optic lightguides and TV camera readout could offer significant improvements in cost per area and reliability over a scintillator plus photomultiplier or a wire proportional chamber array. (author)

  11. A large area cosmic muon detector located at Ohya stone mine

    Science.gov (United States)

    Nii, N.; Mizutani, K.; Aoki, T.; Kitamura, T.; Mitsui, K.; Matsuno, S.; Muraki, Y.; Ohashi, Y.; Okada, A.; Kamiya, Y.

    1985-01-01

    The chemical composition of the primary cosmic rays between 10 to the 15th power eV and 10 to the 18th power eV were determined by a Large Area Cosmic Muon Detector located at Ohya stone mine. The experimental aims of Ohya project are; (1) search for the ultra high-energy gamma-rays; (2) search for the GUT monopole created by Big Bang; and (3) search for the muon bundle. A large number of muon chambers were installed at the shallow underground near Nikko (approx. 100 Km north of Tokyo, situated at Ohya-town, Utsunomiya-city). At the surface of the mine, very fast 100 channel scintillation counters were equipped in order to measure the direction of air showers. These air shower arrays were operated at the same time, together with the underground muon chamber.

  12. Controlled elaboration of large-area plasmonic substrates by plasma process

    International Nuclear Information System (INIS)

    Pugliara, A; Despax, B; Makasheva, K; Bonafos, C; Carles, R

    2015-01-01

    Elaboration in a controlled way of large-area and efficient plasmonic substrates is achieved by combining sputtering of silver nanoparticles (AgNPs) and plasma polymerization of the embedding dielectric matrix in an axially asymmetric, capacitively coupled RF discharge maintained at low gas pressure. The plasma parameters and deposition conditions were optimized according to the optical response of these substrates. Structural and optical characterizations of the samples confirm the process efficiency. The obtained results indicate that to deposit a single layer of large and closely situated AgNPs, a high injected power and short sputtering times must be privileged. The plasma-elaborated plasmonic substrates appear to be very sensitive to any stimuli that affect their plasmonic response. (paper)

  13. Effects of Large Area Liquid Lithium Limiters on Spherical Torus Plasmas

    International Nuclear Information System (INIS)

    Kaita, R.; Majeski, R.; Boaz, M.; Efthimion, P.; Gettelfinger, G.; Gray, T.; Hoffman, D.; Jardin, S.; Kugel, H.; Marfuta, P.; Munsat, T.; Neumeyer, C.; Raftopoulos, S.; Soukhanovskii, V.; Spaleta, J.; Taylor, G.; Timberlake, J.; Woolley, R.; Zakharov, L.; Finkenthal, M.; Stutman, D.; Delgado-Aparicio, L.; Seraydarian, R.P.; Antar, G.; Doerner, R.; Luckhardt, S.; Baldwin, M.; Conn, R.W.; Maingi, R.; Menon, M.; Causey, R.; Buchenauer, D.; Ulrickson, M.; Jones, B.; Rodgers, D.

    2004-01-01

    Use of a large-area liquid lithium surface as a first wall has significantly improved the plasma performance in the Current Drive Experiment-Upgrade (CDX-U) at the Princeton Plasma Physics Laboratory. Previous CDX-U experiments with a partially-covered toroidal lithium limiter tray have shown a decrease in impurities and the recycling of hydrogenic species. Improvements in loading techniques have permitted nearly full coverage of the tray surface with liquid lithium. Under these conditions, there was a large drop in the loop voltage needed to sustain the plasma current. The data are consistent with simulations that indicate more stable plasmas having broader current profiles, higher temperatures, and lowered impurities with liquid lithium walls. As further evidence for reduced recycling with a liquid lithium limiter, the gas puffing had to be increased by up to a factor of eight for the same plasma density achieved with an empty toroidal tray limiter

  14. Effects of large area liquid lithium limiters on spherical torus plasmas

    International Nuclear Information System (INIS)

    Kaita, R.; Majeski, R.; Boaz, M.; Efthimion, P.; Gettelfinger, G.; Gray, T.; Hoffman, D.; Jardin, S.; Kugel, H.; Marfuta, P.; Munsat, T.; Neumeyer, C.; Raftopoulos, S.; Soukhanovskii, V.; Spaleta, J.; Taylor, G.; Timberlake, J.; Woolley, R.; Zakharov, L.; Finkenthal, M.; Stutman, D.; Delgado-Aparicio, L.; Seraydarian, R.P.; Antar, G.; Doerner, R.; Luckhardt, S.; Baldwin, M.; Conn, R.W.; Maingi, R.; Menon, M.; Causey, R.; Buchenauer, D.; Ulrickson, M.; Jones, B.; Rodgers, D.

    2005-01-01

    Use of a large-area liquid lithium surface as a limiter has significantly improved the plasma performance in the Current Drive Experiment-Upgrade (CDX-U) at the Princeton Plasma Physics Laboratory. Previous CDX-U experiments with a partially-covered toroidal lithium limiter tray have shown a decrease in impurities and the recycling of hydrogenic species. Improvements in loading techniques have permitted nearly full coverage of the tray surface with liquid lithium. Under these conditions, there was a large drop in the loop voltage needed to sustain the plasma current. The data are consistent with simulations that indicate more stable plasmas having broader current profiles, higher temperatures, and lowered impurities with liquid lithium walls. As further evidence for reduced recycling with a liquid lithium limiter, the gas puffing had to be increased by up to a factor of eight for the same plasma density achieved with an empty toroidal tray limiter

  15. Large-area functionalized CVD graphene for work function matched transparent electrodes

    Science.gov (United States)

    Bointon, Thomas H.; Jones, Gareth F.; de Sanctis, Adolfo; Hill-Pearce, Ruth; Craciun, Monica F.; Russo, Saverio

    2015-11-01

    The efficiency of flexible photovoltaic and organic light emitting devices is heavily dependent on the availability of flexible and transparent conductors with at least a similar workfunction to that of Indium Tin Oxide. Here we present the first study of the work function of large area (up to 9 cm2) FeCl3 intercalated graphene grown by chemical vapour deposition on Nickel, and demonstrate values as large as 5.1 eV. Upon intercalation, a charge density per graphene layer of 5 ṡ 1013 ± 5 ṡ 1012 cm-2 is attained, making this material an attractive platform for the study of plasmonic excitations in the infrared wavelength spectrum of interest to the telecommunication industry. Finally, we demonstrate the potential of this material for flexible electronics in a transparent circuit on a polyethylene naphthalate substrate.

  16. Large-area cold-cathode grid-controlled electron gun for Antares

    International Nuclear Information System (INIS)

    Scarlett, W.R.; Andrews, K.; Jansen, J.

    1979-01-01

    The CO 2 laser amplifiers used in the Antares inertial confinement fusion project require large-area radial beams of high-energy electrons to ionize the laser medium before the main discharge pulse is applied. We have designed a grid-controlled, cold-cathode electron gun with a cylindrical anode having a window area of 9.3 m 2 . A full diameter, 1/4 length prototype of the Antares gun has been built and tested. The design details of the Antares electron gun will be presented as well as test results from the prototype. Techniques used for the prevention and control of emission and breakdown from the grid will also be discussed

  17. Low-impedance internal linear inductive antenna for large-area flat panel display plasma processing

    International Nuclear Information System (INIS)

    Kim, K.N.; Jung, S.J.; Lee, Y.J.; Yeom, G.Y.; Lee, S.H.; Lee, J.K.

    2005-01-01

    An internal-type linear inductive antenna, that is, a double-comb-type antenna, was developed for a large-area plasma source having the size of 1020 mmx830 mm, and high density plasmas on the order of 2.3x10 11 cm -3 were obtained with 15 mTorr Ar at 5000 W of inductive power with good plasma stability. This is higher than that for the conventional serpentine-type antenna, possibly due to the low impedance, resulting in high efficiency of power transfer for the double-comb antenna type. In addition, due to the remarkable reduction of the antenna length, a plasma uniformity of less than 8% was obtained within the substrate area of 880 mmx660 mm at 5000 W without having a standing-wave effect

  18. Vapor deposition of large area NpO2 and UO2 deposits

    International Nuclear Information System (INIS)

    Adair, H.L.; Gibson, J.R.; Kobisk, E.H.; Dailey, J.M.

    1976-01-01

    Deposition of NpO 2 and UO 2 thin films over an area of 7.5 to 10 cm diam has become a routine operation in preparation of fission chamber plates. Vacuum evaporation or electroplating has been used for this purpose. The ''paint brush'' technique has been used as well; however, uniformity requirements normally eliminate this procedure. Vapor deposition in vacuum appears to be the most suitable technique for preparing NpO 2 and UO 2 deposits of >200 cm 2 . This paper describes the procedures used in preparing uniform large area deposits of NpO 2 (approximately 300 cm 2 ) and UO 2 (approximately 2000 cm 2 ) by vacuum evaporation using electron bombardment heating and several substrate motion and heating methods to achieve uniformity and adhesion

  19. Laboratory and test beam results from a large-area silicon drift detector

    CERN Document Server

    Bonvicini, V; Giubellino, P; Gregorio, A; Idzik, M; Kolojvari, A A; Montaño-Zetina, L M; Nouais, D; Petta, C; Rashevsky, A; Randazzo, N; Reito, S; Tosello, F; Vacchi, A; Vinogradov, L I; Zampa, N

    2000-01-01

    A very large-area (6.75*8 cm/sup 2/) silicon drift detector with integrated high-voltage divider has been designed, produced and fully characterised in the laboratory by means of ad hoc designed MOS injection electrodes. The detector is of the "butterfly" type, the sensitive area being subdivided into two regions with a maximum drift length of 3.3 cm. The device was also tested in a pion beam (at the CERN PS) tagged by means of a microstrip detector telescope. Bipolar VLSI front-end cells featuring a noise of 250 e/sup -/ RMS at 0 pF with a slope of 40 e/sup -//pF have been used to read out the signals. The detector showed an excellent stability and featured the expected characteristics. Some preliminary results will be presented. (12 refs).

  20. Large area silicon drift detectors for x-rays -- New results

    International Nuclear Information System (INIS)

    Iwanczyk, J.S.; Patt, B.E.; Tull, C.R.; Segal, J.D.; Kenney, C.J.; Hedman, B.; Hodgson, K.O.

    1998-01-01

    Large area silicon drift detectors, consisting of 8 mm and 12 mm diameter hexagons, were fabricated on 0.35 mm thick high resistivity n-type silicon. An external FET and a low-noise charge sensitive preamplifier were used for testing the prototype detectors. The detector performance was measured in the range 75 to 25 C using Peltier cooling, and from 0.125 to 6 micros amplifier shaping time. Measured energy resolutions were 159 eV FWHM and 263 eV FWHM for the 0.5 cm 2 and 1 cm 2 detectors, respectively (at 5.9 keV, -75 C, 6 micros shaping time). The uniformity of the detector response over the entire active area (measured using 560 nm light) was < 0.5%

  1. The large-area hybrid-optics CLAS12 RICH detector: Tests of innovative components

    International Nuclear Information System (INIS)

    Contalbrigo, M.; Baltzell, N.; Benmokhtar, F.; Barion, L.; Cisbani, E.; El Alaoui, A.; Hafidi, K.; Hoek, M.; Kubarovsky, V.; Lagamba, L.; Lucherini, V.; Malaguti, R.; Mirazita, M.; Montgomery, R.; Movsisyan, A.; Musico, P.; Orecchini, D.; Orlandi, A.; Pappalardo, L.L.; Pereira, S.

    2014-01-01

    A large area ring-imaging Cherenkov detector has been designed to provide clean hadron identification capability in the momentum range from 3 GeV/c to 8 GeV/c for the CLAS12 experiments at the upgraded 12 GeV continuous electron beam accelerator facility of Jefferson Lab to study the 3D nucleon structure in the yet poorly explored valence region by deep-inelastic scattering, and to perform precision measurements in hadronization and hadron spectroscopy. The adopted solution foresees a novel hybrid optics design based on an aerogel radiator, composite mirrors and densely packed and highly segmented photon detectors. Cherenkov light will either be imaged directly (forward tracks) or after two mirror reflections (large angle tracks). The preliminary results of individual detector component tests and of the prototype performance at test-beams are reported here. - Highlights: • A novel hybrid-optics configuration was proven to work with a large RICH prototype. • Innovative RICH components were studied both in laboratory tests and test-beams. • Aerogel of large Rayleigh scattering length at n=1.05 was characterized. • Novel vs commercially available multi-anode photomultipliers were compared. • The response of SiPM matrices to Cherenkov light was tested at various temperatures

  2. The large-area hybrid-optics CLAS12 RICH detector: Tests of innovative components

    Energy Technology Data Exchange (ETDEWEB)

    Contalbrigo, M., E-mail: contalbrigo@fe.infn.it [INFN Sezione di Ferrara and University of Ferrara (Italy); Baltzell, N. [Argonne National Laboratory, IL (United States); Benmokhtar, F. [Christopher Newport University, VA (United States); Duquesne University, PA (United States); Barion, L. [INFN Sezione di Ferrara and University of Ferrara (Italy); Cisbani, E. [INFN Sezione di Roma – Gruppo Collega to Sanità (Italy); Italian National Institute of Health (Italy); El Alaoui, A. [Universidad Tecnica Federico Santa Maria, Valparaiso (Chile); Argonne National Laboratory, IL (United States); Hafidi, K. [Argonne National Laboratory, IL (United States); Hoek, M. [Glasgow University (United Kingdom); J. Gutenberg Universität, Mainz (Germany); Kubarovsky, V. [Thomas Jefferson National Laboratory, VA (United States); Lagamba, L. [INFN Sezione di Bari, University of Bari (Italy); Lucherini, V. [INFN Laboratori Nazionali di Frascati (Italy); Malaguti, R. [INFN Sezione di Ferrara and University of Ferrara (Italy); Mirazita, M. [INFN Laboratori Nazionali di Frascati (Italy); Montgomery, R. [Glasgow University (United Kingdom); INFN Laboratori Nazionali di Frascati (Italy); Movsisyan, A. [INFN Sezione di Ferrara and University of Ferrara (Italy); Musico, P. [INFN Sezione di Genova (Italy); Orecchini, D.; Orlandi, A. [INFN Laboratori Nazionali di Frascati (Italy); Pappalardo, L.L. [INFN Sezione di Ferrara and University of Ferrara (Italy); Pereira, S. [INFN Laboratori Nazionali di Frascati (Italy); and others

    2014-12-01

    A large area ring-imaging Cherenkov detector has been designed to provide clean hadron identification capability in the momentum range from 3 GeV/c to 8 GeV/c for the CLAS12 experiments at the upgraded 12 GeV continuous electron beam accelerator facility of Jefferson Lab to study the 3D nucleon structure in the yet poorly explored valence region by deep-inelastic scattering, and to perform precision measurements in hadronization and hadron spectroscopy. The adopted solution foresees a novel hybrid optics design based on an aerogel radiator, composite mirrors and densely packed and highly segmented photon detectors. Cherenkov light will either be imaged directly (forward tracks) or after two mirror reflections (large angle tracks). The preliminary results of individual detector component tests and of the prototype performance at test-beams are reported here. - Highlights: • A novel hybrid-optics configuration was proven to work with a large RICH prototype. • Innovative RICH components were studied both in laboratory tests and test-beams. • Aerogel of large Rayleigh scattering length at n=1.05 was characterized. • Novel vs commercially available multi-anode photomultipliers were compared. • The response of SiPM matrices to Cherenkov light was tested at various temperatures.

  3. Large-area parallel near-field optical nanopatterning of functional materials using microsphere mask

    Energy Technology Data Exchange (ETDEWEB)

    Chen, G.X. [NUS Nanoscience and Nanotechnology Initiative, National University of Singapore, 2 Engineering Drive 3, Singapore 117576 (Singapore); Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Hong, M.H. [NUS Nanoscience and Nanotechnology Initiative, National University of Singapore, 2 Engineering Drive 3, Singapore 117576 (Singapore); Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Data Storage Institute, ASTAR, DSI Building, 5 Engineering Drive 1, Singapore 117608 (Singapore)], E-mail: Hong_Minghui@dsi.a-star.edu.sg; Lin, Y. [NUS Nanoscience and Nanotechnology Initiative, National University of Singapore, 2 Engineering Drive 3, Singapore 117576 (Singapore); Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Wang, Z.B. [Data Storage Institute, ASTAR, DSI Building, 5 Engineering Drive 1, Singapore 117608 (Singapore); Ng, D.K.T. [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Data Storage Institute, ASTAR, DSI Building, 5 Engineering Drive 1, Singapore 117608 (Singapore); Xie, Q. [Data Storage Institute, ASTAR, DSI Building, 5 Engineering Drive 1, Singapore 117608 (Singapore); Tan, L.S. [NUS Nanoscience and Nanotechnology Initiative, National University of Singapore, 2 Engineering Drive 3, Singapore 117576 (Singapore); Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Chong, T.C. [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Data Storage Institute, ASTAR, DSI Building, 5 Engineering Drive 1, Singapore 117608 (Singapore)

    2008-01-31

    Large-area parallel near-field optical nanopatterning on functional material surfaces was investigated with KrF excimer laser irradiation. A monolayer of silicon dioxide microspheres was self-assembled on the sample surfaces as the processing mask. Nanoholes and nanospots were obtained on silicon surfaces and thin silver films, respectively. The nanopatterning results were affected by the refractive indices of the surrounding media. Near-field optical enhancement beneath the microspheres is the physical origin of nanostructure formation. Theoretical calculation was performed to study the intensity of optical field distributions under the microspheres according to the light scattering model of a sphere on the substrate.

  4. Transfer and characterization of large-area CVD graphene for transparent electrode applications

    DEFF Research Database (Denmark)

    Whelan, Patrick Rebsdorf

    addresses key issues for industrial integration of large area graphene for optoelectronic devices. This is done through optimization of existing characterization methods and development of new transfer techniques. A method for accurately measuring the decoupling of graphene from copper catalysts...... and the electrical properties of graphene after transfer are superior compared to the standard etching transfer method. Spatial mapping of the electrical properties of transferred graphene is performed using terahertz time-domain spectroscopy (THz-TDS). The non-contact nature of THz-TDS and the fact...

  5. Precisely Controlled Ultrathin Conjugated Polymer Films for Large Area Transparent Transistors and Highly Sensitive Chemical Sensors.

    Science.gov (United States)

    Khim, Dongyoon; Ryu, Gi-Seong; Park, Won-Tae; Kim, Hyunchul; Lee, Myungwon; Noh, Yong-Young

    2016-04-13

    A uniform ultrathin polymer film is deposited over a large area with molecularlevel precision by the simple wire-wound bar-coating method. The bar-coated ultrathin films not only exhibit high transparency of up to 90% in the visible wavelength range but also high charge carrier mobility with a high degree of percolation through the uniformly covered polymer nanofibrils. They are capable of realizing highly sensitive multigas sensors and represent the first successful report of ethylene detection using a sensor based on organic field-effect transistors. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Fabricating large-area metallic woodpile photonic crystals using stacking and rolling

    International Nuclear Information System (INIS)

    Ibbotson, Lindsey A; Baumberg, Jeremy J

    2013-01-01

    Stacking thin polymer films supporting metal nanowire gratings provides a simple route, demonstrated here, to producing large-area metallic woodpile structures with high throughput. Under appropriate conditions the grating films can spontaneously roll up, giving a rapid and controllable method of creating multilayers. The resulting three-dimensional (3D) wire structures are flexible and potentially stretchable. Since this process can be extended to include a wide variety of functional materials, it opens up the manufacture of many tailored 3D optical metamaterials. (paper)

  7. Large-area thin self-supporting carbon foils with MgO coatings

    CERN Document Server

    Stolarz, A

    2002-01-01

    Large area self-supporting carbon foils in the thickness of range of 8-22 mu g/cm sup 2 , coated with approximately 4 mu g/cm sup 2 MgO have been prepared by e-gun evaporation. They were mounted on frames with apertures of 130 cm sup 2. Problems related to the parting agent preparation, floating procedure, and mounting onto frames are discussed. Special precautions necessary to avoid damage during foil drying, storage and transportation are suggested.

  8. Large-area thin self-supporting carbon foils with MgO coatings

    Energy Technology Data Exchange (ETDEWEB)

    Stolarz, Anna E-mail: anna@slcj.uw.edu.pl; Maier-Komor, Peter

    2002-03-11

    Large area self-supporting carbon foils in the thickness of range of 8-22 {mu}g/cm{sup 2}, coated with approximately 4 {mu}g/cm{sup 2} MgO have been prepared by e-gun evaporation. They were mounted on frames with apertures of 130 cm{sup 2}. Problems related to the parting agent preparation, floating procedure, and mounting onto frames are discussed. Special precautions necessary to avoid damage during foil drying, storage and transportation are suggested.

  9. Large-area graphene films by simple solution casting of edge-selectively functionalized graphite.

    Science.gov (United States)

    Bae, Seo-Yoon; Jeon, In-Yup; Yang, Jieun; Park, Noejung; Shin, Hyeon Suk; Park, Sungjin; Ruoff, Rodney S; Dai, Liming; Baek, Jong-Beom

    2011-06-28

    We report edge-selective functionalization of graphite (EFG) for the production of large-area uniform graphene films by simply solution-casting EFG dispersions in dichloromethane on silicon oxide substrates, followed by annealing. The resultant graphene films show ambipolar transport properties with sheet resistances of 0.52-3.11 kΩ/sq at 63-90% optical transmittance. EFG allows solution processing methods for the scalable production of electrically conductive, optically transparent, and mechanically robust flexible graphene films for use in practice.

  10. Development of large area resistive electrodes for ATLAS NSW MicroMEGAS

    CERN Document Server

    Ochi, Atsuhiko; The ATLAS collaboration

    2015-01-01

    MicroMegas with resistive anode will be used for the NSW upgrade of the ATLAS experiment at LHC. The resistive electrode is one of key technology for MPGDs to prevent sparks. Large area resistive electrodes for the MM have been developed using two different technology; screen printing and carbon sputtering. Maximum size of each resistive foil is 45cm x 220cm with printed pattern of 425 micron pitch strips. Those technologies are also suitable to mass production. The prototypes of series production model have been produced successfully. We will report the development and production status and test results of the resistive MicroMegas.

  11. Fabrication of large area homogeneous metallic nanostructures for optical sensing using colloidal lithography

    DEFF Research Database (Denmark)

    Eriksen, René Lynge; Pors, Anders; Dreier, Jes

    2010-01-01

    We propose a simple and reproducible method for fabricating large area metal films with inter-connected nanostructures using a combination of colloidal lithography, metal deposition and a template stripping technique. The method is generic in the sense that it is possible to produce a variety...... to fabricate metal films with inter-connected nanostructures consisting of either partial spherical shells or the inverted structures: spherical cavities. The substrates are characterized by optical reflectance and transmittance spectroscopy. We demonstrate, in the case of partial spherical shells...

  12. Approaching total absorption at near infrared in a large area monolayer graphene by critical coupling

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yonghao; Chadha, Arvinder; Zhao, Deyin; Shuai, Yichen; Menon, Laxmy; Yang, Hongjun; Zhou, Weidong, E-mail: wzhou@uta.edu [Nanophotonics Lab, Department of Electrical Engineering, University of Texas at Arlington, Arlington, Texas 76019 (United States); Piper, Jessica R.; Fan, Shanhui [Ginzton Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States); Jia, Yichen; Xia, Fengnian [Department of Electrical Engineering, Yale University, New Haven, Connecticut 06520 (United States); Ma, Zhenqiang [Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

    2014-11-03

    We demonstrate experimentally close to total absorption in monolayer graphene based on critical coupling with guided resonances in transfer printed photonic crystal Fano resonance filters at near infrared. Measured peak absorptions of 35% and 85% were obtained from cavity coupled monolayer graphene for the structures without and with back reflectors, respectively. These measured values agree very well with the theoretical values predicted with the coupled mode theory based critical coupling design. Such strong light-matter interactions can lead to extremely compact and high performance photonic devices based on large area monolayer graphene and other two–dimensional materials.

  13. Acceptance analysis for a large area monopole experiment using nuclear track detectors

    International Nuclear Information System (INIS)

    Hasegan, Monica; Popa, V.

    1998-01-01

    In this paper, we discuss the acceptance of a horizontal plane of 1000 m 2 nuclear track detector for an anisotropic flux of GUT magnetic monopoles (MM) with m MM ∼ 10 16 GeV and g = g D , 2g D , 3g D , considering the monopole energy loss in Earth. It is estimated that a large area experiment for the search of GUT monopoles that uses such detectors and would operate a reasonable number of years could reach a sensitivity of the order of few 10 -17 cm -2 s -1 sr -1 . (authors)

  14. FERMI/LARGE AREA TELESCOPE BRIGHT GAMMA-RAY SOURCE LIST

    International Nuclear Information System (INIS)

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Borgland, A. W.; Atwood, W. B.; Axelsson, M.; Battelino, M.; Baldini, L.; Bellazzini, R.; Ballet, J.; Band, D. L.; Barbiellini, G.; Bastieri, D.; Baughman, B. M.; Bignami, G. F.; Bonamente, E.

    2009-01-01

    Following its launch in 2008 June, the Fermi Gamma-ray Space Telescope (Fermi) began a sky survey in August. The Large Area Telescope (LAT) on Fermi in three months produced a deeper and better resolved map of the γ-ray sky than any previous space mission. We present here initial results for energies above 100 MeV for the 205 most significant (statistical significance greater than ∼10σ) γ-ray sources in these data. These are the best characterized and best localized point-like (i.e., spatially unresolved) γ-ray sources in the early mission data.

  15. Development of large area si detectors based on planar technology for charged particles

    International Nuclear Information System (INIS)

    Zhang Wanchang; Sun Liang; Huang Xiaojian; Liu Yang; Chen Guozhu

    2009-01-01

    This paper describes the processing method of large area Si detectors fabricated by planar technology for charged particles. In order to decrease the detectors leakage current, the surface passivation technique was used. The paper gives the measurement results of the leakage current of 300μm thick, 20mm diameter detectors and 500μm thick, 40mm diameter detectors respectively. The spectra of the detectors for 241 Am 5.486MeV α particles are also provided at room temperature. (authors)

  16. Microfabrication of large-area circular high-stress silicon nitride membranes for optomechanical applications

    Directory of Open Access Journals (Sweden)

    E. Serra

    2016-06-01

    Full Text Available In view of the integration of membrane resonators with more complex MEMS structures, we developed a general fabrication procedure for circular shape SiNx membranes using Deep Reactive Ion Etching (DRIE. Large area and high-stress SiNx membranes were fabricated and used as optomechanical resonators in a Michelson interferometer, where Q values up to 1.3 × 106 were measured at cryogenic temperatures, and in a Fabry-Pérot cavity, where an optical finesse up to 50000 has been observed.

  17. In situ catalytic growth of large-area multilayered graphene/MoS2 heterostructures

    OpenAIRE

    Fu, Wei; Du, Fei-Hu; Su, Juan; Li, Xin-Hao; Wei, Xiao; Ye, Tian-Nan; Wang, Kai-Xue; Chen, Jie-Sheng

    2014-01-01

    Stacking various two-dimensional atomic crystals on top of each other is a feasible approach to create unique multilayered heterostructures with desired properties. Herein for the first time, we present a controlled preparation of large-area graphene/MoS2 heterostructures via a simple heating procedure on Mo-oleate complex coated sodium sulfate under N2 atmosphere. Through a direct in situ catalytic reaction, graphene layer has been uniformly grown on the MoS2 film formed by the reaction of M...

  18. Study on the performance of large area MRPC with high position resolution

    Energy Technology Data Exchange (ETDEWEB)

    Yue Qian, E-mail: yueq@mail.tsinghua.edu.cn [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Key Laboratory of Particle and Radiation Imaging, Tsinghua University, Ministry of Education (China); Wu Yucheng; Li Yuanjing; Ye Jin; Cheng Jianping; Wang Yi; Li Jin [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Key Laboratory of Particle and Radiation Imaging, Tsinghua University, Ministry of Education (China)

    2012-01-01

    Multi-gap resistive plate chamber (MRPC), which is mostly developed in high energy physics domain with excellent time resolution, is also highlighted in imaging applications. A set of 50 cm Multiplication-Sign 50 cm large area MRPC with high position resolution was successfully developed by our group and different experiments have been done to test its performances. Cosmic ray muons were used to do the test and proper high voltage and working gas were chosen. Data analysis indicates its good detection efficiency and good position resolution, which encourages further study of its application in RPC-PET and muon tomography.

  19. Trends in the development of large area photon detectors for Cherenkov light imaging applications

    CERN Document Server

    Nappi, E

    2003-01-01

    Since the successful operations of hi-tech devices at OMEGA, DELPHI and SLD, the technique of Cherenkov light imaging has gone through an impressive and fruitful evolution driven by the conception of novel large area photon detectors. The well-assessed potentialities of thin CsI films, employed as reflective photoconverters in gas counters operated at atmospheric pressure, will be compared with the promising features of hybrid and multianode vacuum photomultipliers. Recently proposed single-photon gaseous detectors based on GEMs will also be reviewed.

  20. Fabrication of dense wavelength division multiplexing filters with large useful area

    Science.gov (United States)

    Lee, Cheng-Chung; Chen, Sheng-Hui; Hsu, Jin-Cherng; Kuo, Chien-Cheng

    2006-08-01

    Dense Wavelength Division Multiplexers (DWDM), a kind of narrow band-pass filter, are extremely sensitive to the optical thickness error in each composite layer. Therefore to have a large useful coating area is extreme difficult because of the uniformity problem. To enlarge the useful coating area it is necessary to improve their design and their fabrication. In this study, we discuss how the tooling factors at different positions and for different materials are related to the optical performance of the design. 100GHz DWDM filters were fabricated by E-gun evaporation with ion-assisted deposition (IAD). To improve the coating uniformity, an analysis technique called shaping tooling factor (STF) was used to analyze the deviation of the optical thickness in different materials so as to enlarge the useful coating area. Also a technique of etching the deposited layers with oxygen ions was introduced. When the above techniques were applied in the fabrication of 100 GHz DWDM filters, the uniformity was better than +/-0.002% over an area of 72 mm in diameter and better than +/-0.0006% over 20mm in diameter.

  1. Observation and analysis of high-speed human motion with frequent occlusion in a large area

    International Nuclear Information System (INIS)

    Wang, Yuru; Liu, Jiafeng; Liu, Guojun; Tang, Xianglong; Liu, Peng

    2009-01-01

    The use of computer vision technology in collecting and analyzing statistics during sports matches or training sessions is expected to provide valuable information for tactics improvement. However, the measurements published in the literature so far are either unreliably documented to be used in training planning due to their limitations or unsuitable for studying high-speed motion in large area with frequent occlusions. A sports annotation system is introduced in this paper for tracking high-speed non-rigid human motion over a large playing area with the aid of motion camera, taking short track speed skating competitions as an example. The proposed system is composed of two sub-systems: precise camera motion compensation and accurate motion acquisition. In the video registration step, a distinctive invariant point feature detector (probability density grads detector) and a global parallax based matching points filter are used, to provide reliable and robust matching across a large range of affine distortion and illumination change. In the motion acquisition step, a two regions' relationship constrained joint color model and Markov chain Monte Carlo based joint particle filter are emphasized, by dividing the human body into two relative key regions. Several field tests are performed to assess measurement errors, including comparison to popular algorithms. With the help of the system presented, the system obtains position data on a 30 m × 60 m large rink with root-mean-square error better than 0.3975 m, velocity and acceleration data with absolute error better than 1.2579 m s −1 and 0.1494 m s −2 , respectively

  2. Observation and analysis of high-speed human motion with frequent occlusion in a large area

    Science.gov (United States)

    Wang, Yuru; Liu, Jiafeng; Liu, Guojun; Tang, Xianglong; Liu, Peng

    2009-12-01

    The use of computer vision technology in collecting and analyzing statistics during sports matches or training sessions is expected to provide valuable information for tactics improvement. However, the measurements published in the literature so far are either unreliably documented to be used in training planning due to their limitations or unsuitable for studying high-speed motion in large area with frequent occlusions. A sports annotation system is introduced in this paper for tracking high-speed non-rigid human motion over a large playing area with the aid of motion camera, taking short track speed skating competitions as an example. The proposed system is composed of two sub-systems: precise camera motion compensation and accurate motion acquisition. In the video registration step, a distinctive invariant point feature detector (probability density grads detector) and a global parallax based matching points filter are used, to provide reliable and robust matching across a large range of affine distortion and illumination change. In the motion acquisition step, a two regions' relationship constrained joint color model and Markov chain Monte Carlo based joint particle filter are emphasized, by dividing the human body into two relative key regions. Several field tests are performed to assess measurement errors, including comparison to popular algorithms. With the help of the system presented, the system obtains position data on a 30 m × 60 m large rink with root-mean-square error better than 0.3975 m, velocity and acceleration data with absolute error better than 1.2579 m s-1 and 0.1494 m s-2, respectively.

  3. Weak Compliance Undermines the Success of No-Take Zones in a Large Government-Controlled Marine Protected Area

    KAUST Repository

    Campbell, Stuart J.; Hoey, Andrew; Maynard, Jeffrey; Kartawijaya, Tasrif; Cinner, Joshua; Graham, Nicholas A. J.; Baird, Andrew H.

    2012-01-01

    The effectiveness of marine protected areas depends largely on whether people comply with the rules. We quantified temporal changes in benthic composition, reef fish biomass, and fishing effort among marine park zones (including no-take areas

  4. A new herbarium-based method for reconstructing the phenology of plant species across large areas.

    Science.gov (United States)

    Lavoie, Claude; Lachance, Daniel

    2006-04-01

    Phenological data have recently emerged as particularly effective tools for studying the impact of climate change on plants, but long phenological records are rare. The lack of phenological observations can nevertheless be filled by herbarium specimens as long as some correction procedures are applied to take into account the different climatic conditions associated with sampling locations. In this study, we propose a new herbarium-based method for reconstructing the flowering dates of plant species that have been collected across large areas. Coltsfoot (Tussilago farfara L.) specimens from southern Quebec were used to test the method. Flowering dates for coltsfoot herbarium specimens were adjusted according to the date of disappearance of snow cover in the region where they were collected and compared using a reference point (the date of earliest snowmelt). In southern Quebec, coltsfoot blooms earlier at present (15-31 d) than during the first part of the 20th century. This phenomenon is likely associated with the climate warming trends recorded in this region in the last century, especially during the last three decades when the month of April became warmer, thereby favoring very early-flowering cases. The earlier flowering of coltsfoot is, however, only noticeable in large urban areas (Montreal, Quebec City), suggesting a strong urban heat island effect on the flowering of this plant. Herbarium specimens are useful phenological indicators; however, the databases should be carefully examined prior to analysis to detect biases or trends associated with sampling locations.

  5. Solution coating of large-area organic semiconductor thin films with aligned single-crystalline domains

    KAUST Repository

    Diao, Ying

    2013-06-02

    Solution coating of organic semiconductors offers great potential for achieving low-cost manufacturing of large-area and flexible electronics. However, the rapid coating speed needed for industrial-scale production poses challenges to the control of thin-film morphology. Here, we report an approach - termed fluid-enhanced crystal engineering (FLUENCE) - that allows for a high degree of morphological control of solution-printed thin films. We designed a micropillar-patterned printing blade to induce recirculation in the ink for enhancing crystal growth, and engineered the curvature of the ink meniscus to control crystal nucleation. Using FLUENCE, we demonstrate the fast coating and patterning of millimetre-wide, centimetre-long, highly aligned single-crystalline organic semiconductor thin films. In particular, we fabricated thin films of 6,13-bis(triisopropylsilylethynyl) pentacene having non-equilibrium single-crystalline domains and an unprecedented average and maximum mobilities of 8.1±1.2 cm2 V-1 s -1 and 11 cm2 V-1 s-1. FLUENCE of organic semiconductors with non-equilibrium single-crystalline domains may find use in the fabrication of high-performance, large-area printed electronics. © 2013 Macmillan Publishers Limited. All rights reserved.

  6. Identification and Prediction of Large Pedestrian Flow in Urban Areas Based on a Hybrid Detection Approach

    Directory of Open Access Journals (Sweden)

    Kaisheng Zhang

    2016-12-01

    Full Text Available Recently, population density has grown quickly with the increasing acceleration of urbanization. At the same time, overcrowded situations are more likely to occur in populous urban areas, increasing the risk of accidents. This paper proposes a synthetic approach to recognize and identify the large pedestrian flow. In particular, a hybrid pedestrian flow detection model was constructed by analyzing real data from major mobile phone operators in China, including information from smartphones and base stations (BS. With the hybrid model, the Log Distance Path Loss (LDPL model was used to estimate the pedestrian density from raw network data, and retrieve information with the Gaussian Progress (GP through supervised learning. Temporal-spatial prediction of the pedestrian data was carried out with Machine Learning (ML approaches. Finally, a case study of a real Central Business District (CBD scenario in Shanghai, China using records of millions of cell phone users was conducted. The results showed that the new approach significantly increases the utility and capacity of the mobile network. A more reasonable overcrowding detection and alert system can be developed to improve safety in subway lines and other hotspot landmark areas, such as the Bundle, People’s Square or Disneyland, where a large passenger flow generally exists.

  7. Large-area uniform electron doping of graphene by Ag nanofilm

    Directory of Open Access Journals (Sweden)

    Xiaopeng Guo

    2017-04-01

    Full Text Available Graphene has attracted much attention at various research fields due to its unique optical, electronic and mechanical properties. Up to now, graphene has not been widely used in optoelectronic fields due to the lack of large-area uniform doped graphene (n-doped and p-doped with smooth surface. Therefore, it is rather desired to develop some effective doping methods to extend graphene to optoelectronics. Here we developed a novel doping method to prepare large-area (> centimeter scale uniform doped graphene film with a nanoscale roughness(RMS roughness ∼1.4 nm, the method (nano-metal film doping method is simple but effective. Using this method electron doping (electron-injection may be easily realized by the simple thermal deposition of Ag nano-film on a transferred CVD graphene. The doping effectiveness has been proved by Raman spectroscopy and spectroscopic ellipsometry. Importantly, our method sheds light on some potential applications of graphene in optoelectronic devices such as photodetectors, LEDs, phototransistors, solar cells, lasers etc.

  8. The role of printing techniques for large-area dye sensitized solar cells

    International Nuclear Information System (INIS)

    Mariani, Paolo; Vesce, Luigi; Di Carlo, Aldo

    2015-01-01

    The versatility of printing technologies and their intrinsic ability to outperform other techniques in large-area deposition gives scope to revolutionize the photovoltaic (PV) manufacturing field. Printing methods are commonly used in conventional silicon-based PVs to cover part of the production process. Screen printing techniques, for example, are applied to deposit electrical contacts on the silicon wafer. However, it is with the advent of third generation PVs that printing/coating techniques have been extensively used in almost all of the manufacturing processes. Among all the third generation PVs, dye sensitized solar cell (DSSC) technology has been developed up to commercialization levels. DSSCs and modules can be fabricated by adopting all of the main printing techniques on both rigid and flexible substrates. This allows an easy tuning of cell/module characteristics to the desired application. Transparency, colour, shape, layout and other DSSC’s features can be easily varied by changing the printing parameters and paste/ink formulations used in the printing process. This review focuses on large-area printing/coating technologies for the fabrication of DSSCs devices. The most used and promising techniques are presented underlining the process parameters and applications. (paper)

  9. Production of a large area diffuse arc plasma with multiple cathode

    International Nuclear Information System (INIS)

    Wang Cheng; Cui Hai-Chao; Li Wan-Wan; Liao Meng-Ran; Xia Wei-Dong; Xia Wei-Luo

    2017-01-01

    An arc channel at atmospheric pressure tends to shrink generally. In this paper, a non-transferred DC arc plasma device with multiple cathode is introduced to produce a large area arc plasma at atmospheric pressure. This device is comprised of a 42-mm diameter tubular chamber, multiple cathode which is radially inserted into the chamber, and a tungsten anode with a nozzle in its center. In argon/helium atmosphere, a large area and circumferential homogenous diffuse arc plasma, which fills the entire cross section surrounded by the cathode tips, is observed. Results show that the uniformity and stability of diffuse arc plasma are strongly related to the plasma forming gas. Based on these experimental results, an explanation to the arc diffusion is suggested. Moreover, the electron excitation temperature and electron density measured in diffuse helium plasma are much lower than those of constricted arc column, which indicates the diffuse helium plasma probably deviates from the local thermodynamic equilibrium state. Unlike the common non-transferred arc plasma devices, this device can provide a condition for axial-fed feedstock particles. The plasma device is attempted to spheroidize alumina powders by using the central axis to send the powder. Results show that the powder produced is usually a typical hollow sphere. (paper)

  10. Mapping the Large Area Straw Detectors of the COMPASS Experiment With X-Rays

    Science.gov (United States)

    Platzer, K.; Dunnweber, W.; Dedek, N.; Faessler, M.; Geyer, R.; Ilgner, C.; Peshekhonov, V.; Wellenstein, H.

    2005-06-01

    In the COMPASS experiment at CERN, large straw drift tube detectors are used for large-angle tracking. To minimize the total areal density, a self supporting structure of thin-walled plastic tubes was chosen and, hence, a loss in mechanical precision was accepted. A complete mapping of the anode wire coordinate grid was required. An X-ray apparatus using a charge-coupled device (CCD) as imaging detector was built to investigate the mechanical properties and to calibrate (offline) the wire positions. Deviations of typically 200-400 /spl mu/m from the nominal positions, defined by equal spacing, are found across the detector area of 8 m/sup 2/. With a calibration method based on high-resolution CCD imaging and pattern recognition algorithms, the absolute wire coordinates are determined with an accuracy better than 30 /spl mu/m across the whole detector area. Temperature effects are clearly seen. Their inhomogenity limits the achievable accuracy to about 50 /spl mu/m under realistic experimental conditions, which is sufficient in view of the intrinsic straw resolution of 200 /spl mu/m for minimum ionizing particles. The offline calibration was checked with particle tracks in the experimental setup, running COMPASS with 160 GeV/c muons. Tracks reconstructed with other detectors that cover a central angular range were used for this comparison. Good agreement is found between these in situ measurements and the X-ray calibration.

  11. Mapping the large area straw detectors of the COMPASS experiment with X-rays

    CERN Document Server

    Platzer, Klaus; Dünnweber, Wolfgang; Faessler, Martin A; Geyer, Reiner; Ilgner, C; Peshekhonov, Vladimir D; Wellenstein, Hermann

    2005-01-01

    In the COMPASS experiment at CERN, large straw drift tube detectors are used for large-angle tracking. To minimize the total areal density, a self supporting structure of thin-walled plastic tubes was chosen and, hence, a loss in mechanical precision was accepted. A complete mapping of the anode wire coordinate grid was required. An X-ray apparatus using a charge-coupled device (CCD) as imaging detector was built to investigate the mechanical properties and to calibrate (offline) the wire positions. Deviations of typically 200-400 mu m from the nominal positions, defined by equal spacing, are found across the detector area of 8 m/sup 2/. With a calibration method based on high-resolution CCD imaging and pattern recognition algorithms, the absolute wire coordinates are determined with an accuracy better than 30 mu m across the whole detector area. Temperature effects are clearly seen. Their inhomogenity limits the achievable accuracy to about 50 mu m under realistic experimental conditions, which is sufficient...

  12. Automated immunohistochemical method to analyze large areas of the human cortex.

    Science.gov (United States)

    Abbass, Mohamad; Trought, Kathleen; Long, David; Semechko, Anton; Wong, Albert H C

    2018-01-15

    There have been inconsistencies in the histological abnormalities found in the cerebral cortex from patients with schizophrenia, bipolar disorder and major depression. Discrepancies in previously published reports may arise from small sample sizes, inconsistent methodology and biased cell counting. We applied automated quantification of neuron density, neuron size and cortical layer thickness in large regions of the cerebral cortex in psychiatric patients. This method accurately segments DAPI positive cells that are also stained with CUX2 and FEZF2. Cortical layer thickness, neuron density and neuron size were automatically computed for each cortical layer in numerous Brodmann areas. We did not find pronounced cytoarchitectural abnormalities in the anterior cingulate cortex or orbitofrontal cortex in patients with schizophrenia, bipolar disorder or major depressive disorder. There were no significant differences in layer thickness measured in immunohistochemically stained slides compared with traditional Nissl stained slides. Automated cell counts were correlated, reliable and consistent with manual counts, while being much less time-consuming. We demonstrate the validity of using a novel automated analysis approach to post-mortem brain tissue. We were able to analyze large cortical areas and quantify specific cell populations using immunohistochemical markers. Future analyses could benefit from efficient automated analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Investigation on large-area fabrication of vivid shark skin with superior surface functions

    Science.gov (United States)

    Chen, Huawei; Zhang, Xin; Ma, Lingxi; Che, Da; Zhang, Deyuan; Sudarshan, T. S.

    2014-10-01

    Shark skin has attracted worldwide attention because of its superior drag reduction, antifouling performance induced from its unique surface morphology. Although the vivid shark skin has been fabricated by a bio-replicated micro-imprinting approach in previous studies and superior drag reduction effect has been validated in water tunnel, continuous large-area fabrication is still an obstacle to wide apply. In this paper, one novel bio-replication coating technology is proposed for large-area transfer of shark skin based on rapid UV curable paint. Apart from design of coating system, bio-replication accuracy of surface morphology was validated about 97% by comparison between shark skin template and coating surface morphology. Finally, the drag reduction and anti-fouling function of coating surface were tested in water tunnel and open algae pond respectively. Drag reduction rate of coating surface was validated about 12% higher and anti-fouling was proved to about hundred times ameliorate, all of which are more excellent than simple 2D riblet surface.

  14. In situ catalytic growth of large-area multilayered graphene/MoS2 heterostructures

    Science.gov (United States)

    Fu, Wei; Du, Fei-Hu; Su, Juan; Li, Xin-Hao; Wei, Xiao; Ye, Tian-Nan; Wang, Kai-Xue; Chen, Jie-Sheng

    2014-04-01

    Stacking various two-dimensional atomic crystals on top of each other is a feasible approach to create unique multilayered heterostructures with desired properties. Herein for the first time, we present a controlled preparation of large-area graphene/MoS2 heterostructures via a simple heating procedure on Mo-oleate complex coated sodium sulfate under N2 atmosphere. Through a direct in situ catalytic reaction, graphene layer has been uniformly grown on the MoS2 film formed by the reaction of Mo species with S pecies, which is from the carbothermal reduction of sodium sulfate. Due to the excellent graphene ``painting'' on MoS2 atomic layers, the significantly shortened lithium ion diffusion distance and the markedly enhanced electronic conductivity, these multilayered graphene/MoS2 heterostructures exhibit high specific capacity, unprecedented rate performance and outstanding cycling stability, especially at a high current density, when used as an anode material for lithium batteries. This work provides a simple but efficient route for the controlled fabrication of large-area multilayered graphene/metal sulfide heterostructures with promising applications in battery manufacture, electronics or catalysis.

  15. The role of printing techniques for large-area dye sensitized solar cells

    Science.gov (United States)

    Mariani, Paolo; Vesce, Luigi; Di Carlo, Aldo

    2015-10-01

    The versatility of printing technologies and their intrinsic ability to outperform other techniques in large-area deposition gives scope to revolutionize the photovoltaic (PV) manufacturing field. Printing methods are commonly used in conventional silicon-based PVs to cover part of the production process. Screen printing techniques, for example, are applied to deposit electrical contacts on the silicon wafer. However, it is with the advent of third generation PVs that printing/coating techniques have been extensively used in almost all of the manufacturing processes. Among all the third generation PVs, dye sensitized solar cell (DSSC) technology has been developed up to commercialization levels. DSSCs and modules can be fabricated by adopting all of the main printing techniques on both rigid and flexible substrates. This allows an easy tuning of cell/module characteristics to the desired application. Transparency, colour, shape, layout and other DSSC’s features can be easily varied by changing the printing parameters and paste/ink formulations used in the printing process. This review focuses on large-area printing/coating technologies for the fabrication of DSSCs devices. The most used and promising techniques are presented underlining the process parameters and applications.

  16. Verification of surface source's characteristics using large-area 2π gas flow counter

    International Nuclear Information System (INIS)

    Abu Naser Waheed, M.M.; Mikami, S.; Kobayashi, H.; Noda, K.

    1998-09-01

    Power Reactor and Nuclear Fuel Development Corporation (PNC) has large-area 2π gas flow counter for the purpose of measuring activity of surface sources of alpha or beta ray emitter. Surface sources are used for the calibration of radiation measuring equipment for radiation control. Due to sequent use of sources, the surface of these sources are inclined to go in bad condition because of unwanted accidental incidents. For the better calibration achievement of radiation measuring instruments the rate of emission of these sources are to be checked periodically by the large-area 2π gas flow counter. In this paper described that eight U 3 O 8 surface sources were selected from many sources of PNC Tokai Works and activity of these sources was measured by the 2π gas flow counter. The results were compared with the values certified by Japan Radio Isotope Association (JRIA). It is evident from the result of comparison that the surface sources are in good condition, i.e., the sources are reliable to calibrate the radiation control instruments. (author)

  17. Local and global particle and power balance in large area capacitive discharges

    International Nuclear Information System (INIS)

    Cho, Suwon; Lieberman, M A

    2003-01-01

    Large area radio frequency (rf) capacitive discharges have attracted recent interest for materials etching and deposition on large area substrates. A distinguishing feature is that the radial distribution of the absorbed rf power in these discharges depends on the rf voltage across the plates, independent of the radial variation of the plasma density n(r). A reduced set of steady-state fluid equations has been used to investigate the radial variation of n and electron temperature T e . The derived equations are shown to be invariant with respect to pL and pR, where p is the pressure, L is the plate separation and R is the discharge radius, and can be further reduced to the equations of the usual global balance model when R ε , the energy relaxation length. In this limit, the ionization frequency and T e are essentially independent of radius and n can be approximately described by the usual radial profile of a zeroth-order Bessel function. When R≥λ ε , n and T e are predominantly determined by local particle and power balance, and the n and T e radial profiles are flat over most of the volume except near the radial boundary, where n falls and T e rises to account for the increased losses at the boundary. The scale length of the edge density variation in the local balance regime is shown to be proportional to the energy relaxation length

  18. Shellfish Fishery Severely Reduces Condition and Survival of Oystercatchers Despite Creation of Large Marine Protected Areas

    Directory of Open Access Journals (Sweden)

    Simon Verhulst

    2004-06-01

    Full Text Available Fisheries and other human activities pose a global threat to the marine environment. Marine protected areas (MPAs are an emerging tool to cope with such threats. In the Dutch Wadden Sea, large MPAs (covering 31% of all intertidal flats have been created to protect shellfish-eating birds and allow recovery of important habitats. Even though shellfish fishing is prohibited in these areas, populations of shellfish-eating birds in the Wadden Sea have declined sharply. The role of shellfish fisheries in these declines is hotly debated, therefore, we investigated the effectiveness of MPAs for protecting oystercatcher (Haematopus ostralegus populations. Shellfish stocks (cockles, Cerastoderma edule were substantially higher in the MPAs, but surprisingly this has not resulted in a redistribution of wintering oystercatchers. Oystercatchers in unprotected areas had less shellfish in their diet and lower condition (a combined measure of mass and haematological parameters, and their estimated mortality was 43% higher. It is likely, therefore, that shellfish fishing explains at least part of the 40% decline in oystercatcher numbers in recent years. Condition and mortality effects were strongest in males, and the population sex ratio was female biased, in agreement with the fact that males rely more on shellfish. The unprotected areas apparently function as an "ecological trap," because oystercatchers did not respond as anticipated to the artificial spatial heterogeneity in food supply. Consequently, the MPAs are effective on a local scale, but not on a global scale. Similar problems are likely to exist in terrestrial ecosystems, and distribution strategies of target species need to be considered when designing terrestrial and marine protected areas if they are to be effective.

  19. An investigation into the use of large area silicon semiconductors in microwave systems

    International Nuclear Information System (INIS)

    Holliday, H.R.

    1999-09-01

    Semiconductor microwave devices are usually manufactured using micron or sub-micron geometries. The equipment needed for these techniques has a high capital cost and demands high overheads. The material traditionally processed for microwave applications is gallium arsenide but during the period of this investigation a move towards the use of silicon and silicon germanium has emerged. This study, which is essentially practical, covers a range of new ideas for components using large area silicon devices. In the course of the study considerable progress has also been made in the understanding of the behaviour of silicon at microwave frequencies, and some of the initial Concepts were shown to be invalid. An accurate determination of the dielectric constant of silicon has been made using quasi optical techniques at microwave frequencies. The fabrication techniques described originate from methods used at Q-par Angus to manufacture large area silicon nuclear radiation detectors. Developed at the University of Birmingham, these are 'wet chemistry' methods that preclude the need for diffusion or other conventional semiconductor processing techniques. Novel microwave components have been developed using these techniques. These include an optically controlled attenuator with multioctave bandwidth and good dynamic range; window devices to reduce the radar cross section of microwave antennas; and microwave cavity devices including a variable-Q cavity. Concepts for millimeter wave filters are discussed, as are areas for further research. During the attenuator study Wheeler's equations have been extended to cover truncated microstrip. It was observed at an early stage in the work that optical excitation was very effective as a method of controlling the devices. This fits well with current trends in electro-optical devices. The piezo resistance effect in silicon has been briefly investigated and a mechanical attenuator exploiting this effect has been developed. (author)

  20. Large area, label-free imaging of extracellular matrix using telecentricity

    Science.gov (United States)

    Visbal Onufrak, Michelle A.; Konger, Raymond L.; Kim, Young L.

    2017-02-01

    Subtle alterations in stromal tissue structures and organizations within the extracellular matrix (ECM) have been observed in several types of tissue abnormalities, including early skin cancer and wounds. Current microscopic imaging methods often lack the ability to accurately determine the extent of malignancy over a large area, due to their limited field of view. In this research we focus on the development of simple mesoscopic (i.e. between microscopic and macroscopic) biomedical imaging device for non-invasive assessment of ECM alterations over a large, heterogeneous area. In our technology development, a telecentric lens, commonly used in machine vision systems but rarely used in biomedical imaging, serves as a key platform to visualize alterations in tissue microenvironments in a label-free manner over a clinically relevant area. In general, telecentric imaging represents a simple, alternative method for reducing unwanted scattering or diffuse light caused by the highly anisotropic scattering properties of biological tissue. In particular, under telecentric imaging the light intensity backscattered from biological tissue is mainly sensitive to the scattering anisotropy factor, possibly associated with the ECM. We demonstrate the inherent advantages of combining telecentric lens systems with hyperspectral imaging for providing optical information of tissue scattering in biological tissue of murine models, as well as light absorption of hemoglobin in blood vessel tissue phantoms. Thus, we envision that telecentric imaging could potentially serve for simple site-specific, tissue-based assessment of stromal alterations over a clinically relevant field of view in a label-free manner, for studying diseases associated with disruption of homeostasis in ECM.

  1. Large-area printed supercapacitor technology for low-cost domestic green energy storage

    International Nuclear Information System (INIS)

    Tehrani, Z.; Thomas, D.J.; Korochkina, T.; Phillips, C.O.; Lupo, D.; Lehtimäki, S.; O'Mahony, J.; Gethin, D.T.

    2017-01-01

    In this research we demonstrate that a flexible ultra-thin supercapacitor can be fabricated using high volume screen printing process. This has enabled the sequential deposition of current collector, electrode, electrolyte materials and adhesive onto a Polyethylene terephthalate (PET) substrate in order to form flexible electrodes for reliable energy storage applications. The electrodes were based on an activated carbon ink and gel electrolyte each of which were formulated for this application. Supercapacitors that have surface areas from 100 to 1600 mm"2 and an assembled device thickness of 375 μm were demonstrated. The capacitance ranged from 50 to 400 mF. Capacitance of printed carbon electrodes is rarely reported in literature and no references were found. The chemistry developed during this study displayed long-term cycling potential and demonstrated the stability of the capacitor for continued usage. The gel electrolyte developed within this work showed comparable performance to that of a liquid counterpart. This improvement resulted in the reduction in gel resistance from 90Ω to 0.5Ω. Significant reduction was observed for all resistances. The solid-state supercapacitors with the gel electrolyte showed comparable performance to the supercapacitors that used a liquid electrolyte. This large area printed device can be used in future houses for reliable green energy storage. - Highlights: • It has been demonstrated that a flexible supercapacitors with large area storage has been developed. • The simplified architecture has the potential to lead to a new class of printable, thin storage devices. • The specific capacitance of 21 F/g was measured.

  2. Suppression of the Thermal Decomposition Reaction of Forest Combustible Materials in Large-Area Fires

    Science.gov (United States)

    Volkov, R. S.; Zhdanova, A. O.; Kuznetsov, G. V.; Strizhak, P. A.

    2018-05-01

    Experimental investigations on the characteristic time of suppression of the thermal decomposition reaction of typical forest combustible materials (aspen twigs, birch leaves, spruce needles, pine chips, and a mixture of these materials) and the volume of water required for this purpose have been performed for model fire hotbeds of different areas: SFCM = 0.0003-0.007 m2 and SFCM = 0.045-0.245 m2. In the experiments, aerosol water flows with droplets of size 0.01-0.25 mm were used for the spraying of model fire hotbeds, and the density of spraying was 0.02 L/(m2·s). It was established that the characteristics of suppression of a fire by an aerosol water flow are mainly determined by the sizes of the droplets in this flow. Prognostic estimates of changes in the dispersivity of a droplet cloud, formed from large (as large as 0.5 L) "drops" (water agglomerates) thrown down from a height, have been made. It is shown that these changes can influence the conditions and characteristics of suppression of a forest fire. Dependences, allowing one to forecast the characteristics of suppression of the thermal decomposition of forest combustible materials with the use of large water agglomerates thrown down from an aircraft and aerosol clouds formed from these agglomerates in the process of their movement to the earth, are presented.

  3. Autonomous management of a recursive area hierarchy for large scale wireless sensor networks using multiple parents

    Energy Technology Data Exchange (ETDEWEB)

    Cree, Johnathan Vee [Washington State Univ., Pullman, WA (United States); Delgado-Frias, Jose [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-03-01

    Large scale wireless sensor networks have been proposed for applications ranging from anomaly detection in an environment to vehicle tracking. Many of these applications require the networks to be distributed across a large geographic area while supporting three to five year network lifetimes. In order to support these requirements large scale wireless sensor networks of duty-cycled devices need a method of efficient and effective autonomous configuration/maintenance. This method should gracefully handle the synchronization tasks duty-cycled networks. Further, an effective configuration solution needs to recognize that in-network data aggregation and analysis presents significant benefits to wireless sensor network and should configure the network in a way such that said higher level functions benefit from the logically imposed structure. NOA, the proposed configuration and maintenance protocol, provides a multi-parent hierarchical logical structure for the network that reduces the synchronization workload. It also provides higher level functions with significant inherent benefits such as but not limited to: removing network divisions that are created by single-parent hierarchies, guarantees for when data will be compared in the hierarchy, and redundancies for communication as well as in-network data aggregation/analysis/storage.

  4. Suppression of the Thermal Decomposition Reaction of Forest Combustible Materials in Large-Area Fires

    Science.gov (United States)

    Volkov, R. S.; Zhdanova, A. O.; Kuznetsov, G. V.; Strizhak, P. A.

    2018-03-01

    Experimental investigations on the characteristic time of suppression of the thermal decomposition reaction of typical forest combustible materials (aspen twigs, birch leaves, spruce needles, pine chips, and a mixture of these materials) and the volume of water required for this purpose have been performed for model fire hotbeds of different areas: SFCM = 0.0003-0.007 m2 and SFCM = 0.045-0.245 m2. In the experiments, aerosol water flows with droplets of size 0.01-0.25 mm were used for the spraying of model fire hotbeds, and the density of spraying was 0.02 L/(m2·s). It was established that the characteristics of suppression of a fire by an aerosol water flow are mainly determined by the sizes of the droplets in this flow. Prognostic estimates of changes in the dispersivity of a droplet cloud, formed from large (as large as 0.5 L) "drops" (water agglomerates) thrown down from a height, have been made. It is shown that these changes can influence the conditions and characteristics of suppression of a forest fire. Dependences, allowing one to forecast the characteristics of suppression of the thermal decomposition of forest combustible materials with the use of large water agglomerates thrown down from an aircraft and aerosol clouds formed from these agglomerates in the process of their movement to the earth, are presented.

  5. Systematic deficiency of aftershocks in areas of high coseismic slip for large subduction zone earthquakes

    Science.gov (United States)

    Wetzler, Nadav; Lay, Thorne; Brodsky, Emily E.; Kanamori, Hiroo

    2018-01-01

    Fault slip during plate boundary earthquakes releases a portion of the shear stress accumulated due to frictional resistance to relative plate motions. Investigation of 101 large [moment magnitude (Mw) ≥ 7] subduction zone plate boundary mainshocks with consistently determined coseismic slip distributions establishes that 15 to 55% of all master event–relocated aftershocks with Mw ≥ 5.2 are located within the slip regions of the mainshock ruptures and few are located in peak slip regions, allowing for uncertainty in the slip models. For the preferred models, cumulative deficiency of aftershocks within the central three-quarters of the scaled slip regions ranges from 15 to 45%, increasing with the total number of observed aftershocks. The spatial gradients of the mainshock coseismic slip concentrate residual shear stress near the slip zone margins and increase stress outside the slip zone, driving both interplate and intraplate aftershock occurrence near the periphery of the mainshock slip. The shear stress reduction in large-slip regions during the mainshock is generally sufficient to preclude further significant rupture during the aftershock sequence, consistent with large-slip areas relocking and not rupturing again for a substantial time. PMID:29487902

  6. Heat-stress increase under climate change twice as large in cities as in rural areas

    Science.gov (United States)

    Wouters, Hendrik; De Ridder, Koen; Poelmans, Lien; Willems, Patrick; Brouwers, Johan; Hosseinzadehtalaei, Parisa; Tabari, Hossein; Vanden Broucke, Sam; van Lipzig, Nicole P. M.; Demuzere, Matthias

    2017-04-01

    Urban areas, being warmer than their surroundings, are particularly vulnerable to global warming and associated increases in extreme temperatures. Yet ensemble climate-model projections are generally performed on a scale that is too coarse to represent the evolution of temperatures in cities. Here, for the first time, we combine a 35-year convection-permitting climate model integrations with information from an ensemble of general circulation models to assess heat stress in a typical densely populated mid-latitude maritime region. We show that the heat-stress increase for the mid-21st century is twice as large in cities compared to their surrounding rural areas. The exacerbation is driven by the urban heat island itself, its concurrence with heatwaves, and urban expansion. Cities experience a heat-stress multiplication by a factor 1.4 and 15 depending on the scenario. Remarkably, the future heat-stress surpasses everywhere the urban hot spots of today. Our novel insights exemplify the need to combine information from climate models, acting on different scales, for climate-change risk assessment in heterogeneous regions. Moreover, these results highlight the necessity for adaptation to increasing heat stress, especially in urban areas.

  7. Large-scale Estimates of Leaf Area Index from Active Remote Sensing Laser Altimetry

    Science.gov (United States)

    Hopkinson, C.; Mahoney, C.

    2016-12-01

    Leaf area index (LAI) is a key parameter that describes the spatial distribution of foliage within forest canopies which in turn control numerous relationships between the ground, canopy, and atmosphere. The retrieval of LAI has demonstrated success by in-situ (digital) hemispherical photography (DHP) and airborne laser scanning (ALS) data; however, field and ALS acquisitions are often spatially limited (100's km2) and costly. Large-scale (>1000's km2) retrievals have been demonstrated by optical sensors, however, accuracies remain uncertain due to the sensor's inability to penetrate the canopy. The spaceborne Geoscience Laser Altimeter System (GLAS) provides a possible solution in retrieving large-scale derivations whilst simultaneously penetrating the canopy. LAI retrieved by multiple DHP from 6 Australian sites, representing a cross-section of Australian ecosystems, were employed to model ALS LAI, which in turn were used to infer LAI from GLAS data at 5 other sites. An optimally filtered GLAS dataset was then employed in conjunction with a host of supplementary data to build a Random Forest (RF) model to infer predictions (and uncertainties) of LAI at a 250 m resolution across the forested regions of Australia. Predictions were validated against ALS-based LAI from 20 sites (R2=0.64, RMSE=1.1 m2m-2); MODIS-based LAI were also assessed against these sites (R2=0.30, RMSE=1.78 m2m-2) to demonstrate the strength of GLAS-based predictions. The large-scale nature of current predictions was also leveraged to demonstrate large-scale relationships of LAI with other environmental characteristics, such as: canopy height, elevation, and slope. The need for such wide-scale quantification of LAI is key in the assessment and modification of forest management strategies across Australia. Such work also assists Australia's Terrestrial Ecosystem Research Network, in fulfilling their government issued mandates.

  8. Polarization-maintaining performance of large effective area, higher order modes fiber in a coiled configuration

    Science.gov (United States)

    Ahmad, Raja; Nicholson, Jeffrey W.; Abedin, Kazi S.; Westbrook, Paul S.; Headley, Clifford; Wisk, Patrick W.; Monberg, Eric M.; Yan, Man F.; DiGiovanni, David J.

    2018-02-01

    Scaling the power-level of fiber sources has many practical advantages, while also enabling fundamental studies on the light-matter interaction in amorphous guiding media. In order to scale the power-level of fiber-sources without encountering nonlinear impairments, a strategy is to increase the effective-area of the guided optical-mode. Increasing the effective-area of the fundamental mode in a fiber, however, presents the challenges of increased susceptibility to mode-distortion and effective-area-reduction under the influence of bends. Therefore, higher-order-mode (HOM) fibers, which guide light in large effective-area (Aeff) Bessel-like modes, are a good candidate for scaling the power-level of robust fiber-sources. Many applications of high-power fiber-sources also demand a deterministic control on the polarization-state of light. Furthermore, a polarization-maintaining (PM)-type HOM fiber can afford the added possibility of coherent-beam combination and polarization multiplexing of high-power fiber-lasers. Previously, we reported polarization-maintaining operation in a 1.3 m length of PM-HOM fiber that was held straight. The PM-HOM fiber guided Bessel-like modes with Aeff ranging from 1200-2800 μm2. In this work, we report, for the first time, that the polarization-extinction-ratio (PER) of the HOM exceeds 10 dB in an 8 m long fiber that is coiled down to a diameter of 40 cm. This opens a path towards compact and polarization-controlled high-power fiber-systems.

  9. Bedform morphology of salmon spawning areas in a large gravel-bed river

    Energy Technology Data Exchange (ETDEWEB)

    Hanrahan, Timothy P.

    2007-05-01

    While the importance of river channel morphology to salmon spawning habitat is increasingly recognized, quantitative measures of the relationships between channel morphology and habitat use are lacking. Such quantitative measures are necessary as management and regulatory agencies within the Pacific Northwestern region of the USA, and elsewhere, seek to quantify potential spawning habitat and develop recovery goals for declining salmon populations. The objective of this study was to determine if fall Chinook salmon (Oncorhynchus tshawytscha) spawning areas in the Snake River, Idaho, USA, were correlated with specific bed form types at the pool-riffle scale. A bed form differencing technique was used to objectively quantify the longitudinal riverbed profile into four distinct pool-riffle units that were independent of discharge. The vertical location of thalweg points within these units was quantified with a riffle proximity index. Chinook salmon spawning areas were mapped and correlated with the pool-riffle units through the use of cross-tabulation tables. The results indicate that 84% of fall Chinook salmon spawning areas were correlated with riffles (Chi-square=152.1, df=3, p<0.001), with 53% of those areas located on the upstream side of riffle crests. The majority of Snake River fall Chinook salmon spawning occurred at a vertical location within 80% of the nearest riffle crest elevation. The analyses of bed form morphology will assist regional fish mangers in quantifying existing and potential fall Chinook salmon spawning habitat, and will provide a quantitative framework for evaluating general ecological implications of channel morphology in large gravel-bed rivers.

  10. Mapping Forest Canopy Height Across Large Areas by Upscaling ALS Estimates with Freely Available Satellite Data

    Directory of Open Access Journals (Sweden)

    Phil Wilkes

    2015-09-01

    Full Text Available Operational assessment of forest structure is an on-going challenge for land managers, particularly over large, remote or inaccessible areas. Here, we present an easily adopted method for generating a continuous map of canopy height at a 30 m resolution, demonstrated over 2.9 million hectares of highly heterogeneous forest (canopy height 0–70 m in Victoria, Australia. A two-stage approach was utilized where Airborne Laser Scanning (ALS derived canopy height, captured over ~18% of the study area, was used to train a regression tree ensemble method; random forest. Predictor variables, which have a global coverage and are freely available, included Landsat Thematic Mapper (Tasselled Cap transformed, Moderate Resolution Imaging Spectroradiometer Normalized Difference Vegetation Index time series, Shuttle Radar Topography Mission elevation data and other ancillary datasets. Reflectance variables were further processed to extract additional spatial and temporal contextual and textural variables. Modeled canopy height was validated following two approaches; (i random sample cross validation; and (ii with 108 inventory plots from outside the ALS capture extent. Both the cross validation and comparison with inventory data indicate canopy height can be estimated with a Root Mean Square Error (RMSE of ≤ 31% (~5.6 m at the 95th percentile confidence interval. Subtraction of the systematic component of model error, estimated from training data error residuals, rescaled canopy height values to more accurately represent the response variable distribution tails e.g., tall and short forest. Two further experiments were carried out to test the applicability and scalability of the presented method. Results suggest that (a no improvement in canopy height estimation is achieved when models were constructed and validated for smaller geographic areas, suggesting there is no upper limit to model scalability; and (b training data can be captured over a small

  11. Large area thinned planar sensors for future high-luminosity-LHC upgrades

    International Nuclear Information System (INIS)

    Wittig, T.; Lawerenz, A.; Röder, R.

    2016-01-01

    Planar hybrid silicon sensors are a well proven technology for past and current particle tracking detectors in HEP experiments. However, the future high-luminosity upgrades of the inner trackers at the LHC experiments pose big challenges to the detectors. A first challenge is an expected radiation damage level of up to 2⋅ 10 16 n eq /cm 2 . For planar sensors, one way to counteract the charge loss and thus increase the radiation hardness is to decrease the thickness of their active area. A second challenge is the large detector area which has to be built as cost-efficient as possible. The CiS research institute has accomplished a proof-of-principle run with n-in-p ATLAS-Pixel sensors in which a cavity is etched to the sensor's back side to reduce its thickness. One advantage of this technology is the fact that thick frames remain at the sensor edges and guarantee mechanical stability on wafer level while the sensor is left on the resulting thin membrane. For this cavity etching technique, no handling wafers are required which represents a benefit in terms of process effort and cost savings. The membranes with areas of up to ∼ 4 × 4 cm 2 and thicknesses of 100 and 150 μm feature a sufficiently good homogeneity across the whole wafer area. The processed pixel sensors show good electrical behaviour with an excellent yield for a suchlike prototype run. First sensors with electroless Ni- and Pt-UBM are already successfully assembled with read-out chips.

  12. Large area thinned planar sensors for future high-luminosity-LHC upgrades

    Science.gov (United States)

    Wittig, T.; Lawerenz, A.; Röder, R.

    2016-12-01

    Planar hybrid silicon sensors are a well proven technology for past and current particle tracking detectors in HEP experiments. However, the future high-luminosity upgrades of the inner trackers at the LHC experiments pose big challenges to the detectors. A first challenge is an expected radiation damage level of up to 2ṡ 1016 neq/cm2. For planar sensors, one way to counteract the charge loss and thus increase the radiation hardness is to decrease the thickness of their active area. A second challenge is the large detector area which has to be built as cost-efficient as possible. The CiS research institute has accomplished a proof-of-principle run with n-in-p ATLAS-Pixel sensors in which a cavity is etched to the sensor's back side to reduce its thickness. One advantage of this technology is the fact that thick frames remain at the sensor edges and guarantee mechanical stability on wafer level while the sensor is left on the resulting thin membrane. For this cavity etching technique, no handling wafers are required which represents a benefit in terms of process effort and cost savings. The membranes with areas of up to ~ 4 × 4 cm2 and thicknesses of 100 and 150 μm feature a sufficiently good homogeneity across the whole wafer area. The processed pixel sensors show good electrical behaviour with an excellent yield for a suchlike prototype run. First sensors with electroless Ni- and Pt-UBM are already successfully assembled with read-out chips.

  13. Applications of large-area nanopatterning to energy generation and storage devices

    Science.gov (United States)

    Mills, Eric N.

    This dissertation encompasses the creation and testing of nanostructured, electrochemically-active energy generation and storage devices, and development of the associated fabrication techniques. The fabricated devices include nanopatterned, plasmonically-active, TiO2+Au thin films for Photocatalytic Water Splitting (PCW), TiO2-based Dye-Sensitized Solar Cells (DSSCs) incorporating nanopatterned, plasmonically-active metallic front electrodes, and Si nanopillar anodes for Li-ion batteries. Techniques were also developed for encapsulation and removal of wet-etched Si nanowires from their mother substrates. TiO2 was the first material to be widely used for PCW. Its use is hampered by its large bandgap (~3.2eV), and poor recombination lifetimes. Au nanoparticles (NPs) have been previously used to improve recombination lifetimes in TiO2 by separating photogenerated carriers near the NP edges, and to increase photocurrents by injecting plasmonically-excited hot electrons into the TiO2 conduction band. Using nanostructured TiO 2+Au electrodes, we aim to increase the PCW efficiency of TiO2 -based electrodes. Dye-sensitized solar cells (DSSCs) employ visible-absorbing dyes anchored to a high-surface-area semiconducting scaffold. The front transparent conducting electrode (TCE) is typically ITO, a scarce and expensive material. We aim to increase the efficiency of thin-film DSSCs and eliminate the use of ITO by using a metallic subwavelength array (MESH) of nanoholes as the front TCE. Silicon holds promise as a high-capacity anode material for Li-ion batteries, as it can store ~10x the Li of graphite, the current leading anode material (3569 vs. 372 mAh/g). However, Si undergoes dramatic (>300%) volume expansion upon "lithiation", pulverizing any structure with non-nanoscopic dimensions (>250nm). We created large-area arrays of "nanopillars" with sub-100nm diameters, using roll-to-roll-compatible flexible-mold NIL on commercially-available metal substrates. Ordered

  14. Exposure doses received from a large scale fire in the restricted area

    International Nuclear Information System (INIS)

    Kawakami, Hiroto; Yamada, Norikazu; Shimomura, Masanori; Ichiki, Takahiko; Kajimoto, Mitsuhiro; Kasahara, Fumio; Tanemura, Munenori; Tsuchino, Susumu; Okubo, Atsushi

    2012-02-01

    At the request of the Local Nuclear Emergency Response Headquarters established in Fukushima Prefecture, Japan Nuclear Energy Safety Organization (JNES) has estimated exposure doses of a fireman and the public during a large scale fire in the restricted area. Data on the contamination of the area were compiled and contaminants deposited on combustible materials in forests were investigated. Estimated doses during a fire vary widely due to the uncertainties and variations in assessment methods, location of the fire (radioactivity in the area, amounts of combustible substance and so on), the scale of the fire (the area of fire spreading), weather conditions (wind direction, wind speed, turbulence type and so on), and the distances of the fireman and the public from the fire. In this reports, effects of these factors were integrated as fire-effect indexes. One can easily obtain exposure doses by multiplying these indexes to the results in each of the assessing conditions. In the severer conditions such as 20 hs of fire spreading area, a contaminant concentration of 6 MBq/m"2 in the area, external dose of a fireman working in the highest air contaminated zone in the vicinity of the fire for 1 hour is estimated to be 50 μSv. If he does not wear a front mask, the internal committed dose is estimated to be 430 μSv. Sum of these doses can rise up to 480 μSv. External and internal doses of the public at the severest location in the distance of 2 km from the fire for 1 hour is estimated to be 5 μSv and 45 μSv respectively, and the sum of these doses is 50 μSv. In the stable conditions where a plume of fire can reach to a longer distance without dispersion, external and internal doses of the public at the 20 km distance from the fire for 1 hour are estimated to be 0.5 μSv and 4.5 μSv respectively, and the sum of them is less than 5 μSv. Though the total exposure dose will not exceed 1 mSv even if the fire lingers for some days, monitoring of radiation is important in

  15. Terahertz emission from a large-area GaInAsN emitter

    International Nuclear Information System (INIS)

    Peter, Falk; Winnerl, Stephan; Schneider, Harald; Helm, Manfred; Koehler, Klaus

    2008-01-01

    A large-area interdigitated terahertz emitter based on molecular-beam epitaxy grown GaInAsN with an additional AlGaAs heterostructure is investigated as a terahertz source for excitation wavelengths between 1.1 and 1.5 μm. The optical and electrical properties of the emitter material exhibit absorption up to a wavelength of 1.5 μm and have a resistivity of 550 kΩ cm. Terahertz waves were detected by electro-optical sampling with a bandwidth exceeding 2 THz. Best performance is found for excitation wavelengths below 1.35 μm. Furthermore the emission properties for several excitation powers are investigated, showing a linear increase in terahertz emission

  16. New bounds on axionlike particles from the Fermi Large Area Telescope observation of PKS 2155 -304

    Science.gov (United States)

    Zhang, Cun; Liang, Yun-Feng; Li, Shang; Liao, Neng-Hui; Feng, Lei; Yuan, Qiang; Fan, Yi-Zhong; Ren, Zhong-Zhou

    2018-03-01

    The axionlike particle (ALP)-photon mixing in the magnetic field around γ -ray sources or along the line of sight could induce oscillation between photons and ALPs, which then causes irregularities in the γ -ray spectra. In this work we search for such spectral irregularities in the spectrum of PKS 2155 -304 using 8.6 years of data from the Fermi Large Area Telescope (Fermi-LAT). No significant evidence for the presence of ALP-photon oscillation is obtained, and the parameter space of ALPs is constrained. The exclusion region sensitively depends on the poorly known magnetic field of the host galaxy cluster of PKS 2155 -304 . If the magnetic field is as high as ˜10 μ G , the "holelike" parameter region allowed in Ref. [1] can be ruled out.

  17. Photovoltaic properties of conjugated polymer/fullerene composites on large area flexible substrates

    Directory of Open Access Journals (Sweden)

    Desta Gebeyehu

    2000-06-01

    Full Text Available In this paper we present measurements of the photovoltaic response of bulk donor-acceptor heterojunction between the conjugated polymer, poly(3-octylthiophene, P3OT, (as a donor, D and fullerene (methanofullerene, (as acceptor, A, deposited between indium tin oxide and aluminum electrodes. The innovation involves the substrate, which is a polymer foil instead of glass. These devices are based on ultrafast, reversible, metastable photoinduced electron transfer and charge separation. We also present the efficiency and stability studies on large area (6 cm x 6 cm flexible plastic solar cells with monochromatic energy conversion efficiency (e of about 1.5% and carrier collection efficiency of nearly 20%. Further more, we have investigated the surface network morphology of these films layers by atomic force microscope (AFM. The development of solar cells based on composites of organic conjugated semi-conducting polymers with fullerene derivatives can provide a new method in the exploitation of solar energy.

  18. The on-orbit calibration of the Fermi Large Area Telescope

    Energy Technology Data Exchange (ETDEWEB)

    Ackermann, M.; Ajello, M.; Bartelt, J.; Bechtol, K.; Berenji, B.; Bloom, E.D.; Bogart, J.R.; Borgland, A.W.; Bouvier, A.; Cameron, R.A.; Campell, M.; Charles, E.; Chiang, J.; Claus, R.; Condamoor, S.; Digel, S.W.; Silva, E.D.E.; Drell, P.S.; Dubois, R.; Edmonds, Y.; Flath, D.L.; Focke, W.B.; Fouts, K.; Freytag, D.; Funk, S.; Glanzman, T.; Godfrey, G.; Goodman, J.; Hakimi, M.; Haller, G.; Hart, P.A.; Huffer, M.; Johannesson, G.; Johnson, A.S.; Kamae, T.; Kavelaars, A.; Kelly, H.; Kocian, M.L.; Lee, S.H.; Madejski, G.M.; Michelson, P.F.; Mitra, P.; Mitthumsiri, W.; Monzani, M.E.; Moskalenko, I.V.; Murgia, S.; Nelson, D.; Nolan, P.L.; Paneque, D.; Panetta, J.H.; Rochester, L.S.; Romani, R.W.; Sapozhnikov, L.; Saxton, O.H.; Sugizaki, M.; Tajima, H.; Tanaka, T.; Thayer, J.B.; Thayer, J.G.; Tramacere, A.; Turri, M.; Usher, T.L.; Wai, L.L.; Waite, A.P.; Wang, P. [Stanford Univ, WW Hansen Expt Phys Lab, Kavli Inst Particle Astrophys and Cosmol, Dept Phys, Stanford, CA 94305 (United States); Ackermann, M.; Ajello, M.; Bartelt, J.; Bechtol, K.; Berenji, B.; Bloom, E.D.; Bogart, J.R.; Borgland, A.W.; Bouvier, A.; Cameron, R.A.; Campell, M.; Charles, E.; Chiang, J.; Claus, R.; Condamoor, S.; Digel, S.W.; Silva, E.D.E.; Drell, P.S.; Dubois, R.; Edmonds, Y.; Flath, D.L.; Focke, W.B.; Fouts, K.; Freytag, D.; Funk, S.; Glanzman, T.; Godfrey, G.; Goodman, J.; Hakimi, M.; Haller, G.; Hart, P.A.; Huffer, M.; Johannesson, G.; Johnson, A.S.; Kamae, T.; Kavelaars, A.; Kelly, H.; Kocian, M.L.; Lee, S.H.; Madejski, G.M.; Michelson, P.F.; Mitra, P.; Mitthumsiri, W.; Monzani, M.E.; Moskalenko, I.V.; Murgia, S.; Nelson, D.; Nolan, P.L.; Paneque, D.; Panetta, J.H.; Rochester, L.S.; Romani, R.W.; Sapozhnikov, L.; Saxton, O.H.; Sugizaki, M.; Tajima, H.; Tanaka, T.; Thayer, J.B; Thayer, J.G.; Tramacere, A.; Turri, M.; Usher, T.L.; Wai, L.L.; Waite, A.P.; Wang, P. [Stanford Univ, SLAC Natl Accelerator Lab, Stanford, CA 94305 (United States)] [and others

    2009-07-01

    The Large Area Telescope (LAT) on-board the Fermi Gamma-ray Space Telescope began its on-orbit operations on June 23, 2008. Calibrations, defined in a generic sense, correspond to synchronization of trigger signals, optimization of delays for latching data, determination of detector thresholds, gains and responses, evaluation of the perimeter of the South Atlantic Anomaly (SAA), measurements of live time, of absolute time, and internal and spacecraft bore-sight alignments. Here we describe on-orbit calibration results obtained using known astrophysical sources, galactic cosmic rays, and charge injection into the front-end electronics of each detector. Instrument response functions will be described in a separate publication. This paper demonstrates the stability of calibrations and describes minor changes observed since launch. These results have been used to calibrate the LAT datasets to be publicly released in August 2009. (authors)

  19. Planning for cleanup of large areas contaminated as a result of a nuclear accident

    International Nuclear Information System (INIS)

    1991-01-01

    The cleanup of large areas of contaminated as a result of an accident at a nuclear facility could cost hundreds of millions of dollars and cause inconvenience to the public. Such a cleanup programme would be undertaken only if the detriment to health and social life resulting from cleanup activities would be less than that resulting from further exposures. All reasonable means should, however, be used to minimize the costs and detriment to humans of such a cleanup. For such a cleanup to be carried out safely, efficiently and as quickly as possible under adverse conditions requires: Good preliminary and final planning; A cleanup team having a well defined management structure and well trained personnel; and Suitable cleanup methods and equipment and cleanup criteria. 35 refs, 8 figs, 5 tabs

  20. Tuning the thickness of electrochemically grafted layers in large area molecular junctions

    Energy Technology Data Exchange (ETDEWEB)

    Fluteau, T.; Bessis, C.; Barraud, C., E-mail: clement.barraud@univ-paris-diderot.fr; Della Rocca, M. L.; Lafarge, P. [Université Paris Diderot, Sorbonne Paris Cité, MPQ, UMR 7162, CNRS, 75205 Paris Cedex 13 (France); Martin, P.; Lacroix, J.-C. [Université Paris Diderot, Sorbonne Paris Cité, ITODYS, UMR 7086, CNRS, 15 rue J.-A. de Baïf, 75205 Paris Cedex 13 (France)

    2014-09-21

    We have investigated the thickness, the surface roughness, and the transport properties of oligo(1-(2-bisthienyl)benzene) (BTB) thin films grafted on evaporated Au electrodes, thanks to a diazonium-based electro-reduction process. The thickness of the organic film is tuned by varying the number of electrochemical cycles during the growth process. Atomic force microscopy measurements reveal the evolution of the thickness in the range of 2–27 nm. Its variation displays a linear dependence with the number of cycles followed by a saturation attributed to the insulating behavior of the organic films. Both ultrathin (2 nm) and thin (12 and 27 nm) large area BTB-based junctions have then been fabricated using standard CMOS processes and finally electrically characterized. The electronic responses are fully consistent with a tunneling barrier in case of ultrathin BTB film whereas a pronounced rectifying behavior is reported for thicker molecular films.

  1. Large area imaging of hydrogenous materials using fast neutrons from a DD fusion generator

    Energy Technology Data Exchange (ETDEWEB)

    Cremer, J.T., E-mail: ted@adelphitech.com [Adelphi Technology Inc., 2003 East Bayshore Road, Redwood City, California 94063 (United States); Williams, D.L.; Gary, C.K.; Piestrup, M.A.; Faber, D.R.; Fuller, M.J.; Vainionpaa, J.H.; Apodaca, M. [Adelphi Technology Inc., 2003 East Bayshore Road, Redwood City, California 94063 (United States); Pantell, R.H.; Feinstein, J. [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States)

    2012-05-21

    A small-laboratory fast-neutron generator and a large area detector were used to image hydrogen-bearing materials. The overall image resolution of 2.5 mm was determined by a knife-edge measurement. Contact images of objects were obtained in 5-50 min exposures by placing them close to a plastic scintillator at distances of 1.5 to 3.2 m from the neutron source. The generator produces 10{sup 9} n/s from the DD fusion reaction at a small target. The combination of the DD-fusion generator and electronic camera permits both small laboratory and field-portable imaging of hydrogen-rich materials embedded in high density materials.

  2. Spectral analysis of the Crab Pulsar and Nebula with the Fermi Large Area Telescope

    International Nuclear Information System (INIS)

    Loparco, F.

    2011-01-01

    The Crab Pulsar is a relatively young neutron star. The Pulsar is the central star in the Crab Nebula, a remnant of the supernova SN 1054, which was observed on Earth in the year 1054. The Crab Pulsar has been extensively observed in the gamma-ray energy band by the Large Area Telescope (LAT), the main instrument onboard the Fermi gamma-ray space telescope, during its first months of data taking. The LAT data have been used to reconstruct the fluxes and the energy spectra of the pulsed gamma-ray component and of the gamma-rays from the Nebula. The results on the pulsed component are in good agreement with the previous measurement from EGRET, while the results on the Nebula are consistent with the observations from Earth based telescopes.

  3. Magnetic Carpet Probe for Large Area Instant Crack/Corrosion Detection and Health Monitoring

    International Nuclear Information System (INIS)

    Sun Yushi; Ouyang Tianhe; Yang Xinle; Zhu Haiou

    2007-01-01

    Recently a new NDE tool, Magnet Carpet Probe (MCP), has been developed by Innovative Materials Testing Technologies, Inc. supported by FAA to meet the demands of large area crack/corrosion detection and health monitoring. MCP is a two-dimensional coil array built on a piece of very thin flexible printed circuit board. A two-dimensional electromagnetic scan is going on within the MCP placed on top of a metallic surface under inspection. Therefore, one can finish the inspection, without moving anything, and see the crack/corrosion identification image on the instrument screen in a few second. Recent test results show that it can detect 0.030 x 0.016'' EDM notches on a Titanium standard; 0.024'' ∼ 0.036: real cracks on titanium standards, as well as penetrate through a 0.040'' aluminum layer for corrosion detection

  4. Quality control for the first large areas of triple-GEM chambers for the CMS endcaps

    Science.gov (United States)

    Abbaneo, D.; Abbas, M.; Abbrescia, M.; Abi Akl, M.; Aboamer, O.; Acosta, D.; Ahmad, A.; Ahmed, W.; Aleksandrov, A.; Altieri, P.; Asawatangtrakuldee, C.; Aspell, P.; Assran, Y.; Awan, I.; Bally, S.; Ban, Y.; Banerjee, S.; Barashko, V.; Barria, P.; Bencze, G.; Beni, N.; Benussi, L.; Bhopatkar, V.; Bianco, S.; Bos, J.; Bouhali, O.; Braghieri, A.; Braibant, S.; Buontempo, S.; Calabria, C.; Caponero, M.; Caputo, C.; Cassese, F.; Castaneda, A.; Cauwenbergh, S.; Cavallo, F. R.; Celik, A.; Choi, M.; Choi, S.; Christiansen, J.; Cimmino, A.; Colafranceschi, S.; Colaleo, A.; Conde Garcia, A.; Czellar, S.; Dabrowski, M. M.; De Lentdecker, G.; De Oliveira, R.; de Robertis, G.; Dildick, S.; Dorney, B.; Endroczi, G.; Errico, F.; Fenyvesi, A.; Ferry, S.; Furic, I.; Giacomelli, P.; Gilmore, J.; Golovtsov, V.; Guiducci, L.; Guilloux, F.; Gutierrez, A.; Hadjiiska, R. M.; Hauser, J.; Hoepfner, K.; Hohlmann, M.; Hoorani, H.; Iaydjiev, P.; Jeng, Y. G.; Kamon, T.; Karchin, P.; Korytov, A.; Krutelyov, S.; Kumar, A.; Kim, H.; Lee, J.; Lenzi, T.; Litov, L.; Loddo, F.; Madorsky, A.; Maerschalk, T.; Maggi, M.; Magnani, A.; Mal, P. K.; Mandal, K.; Marchioro, A.; Marinov, A.; Majumdar, N.; Merlin, J. A.; Mitselmakher, G.; Mohanty, A. K.; Mohapatra, A.; Molnar, J.; Muhammad, S.; Mukhopadhyay, S.; Naimuddin, M.; Nuzzo, S.; Oliveri, E.; Pant, L. M.; Paolucci, P.; Park, I.; Passeggio, G.; Pavlov, B.; Philipps, B.; Piccolo, D.; Postema, H.; Puig Baranac, A.; Radi, A.; Radogna, R.; Raffone, G.; Ranieri, A.; Rashevski, G.; Riccardi, C.; Rodozov, M.; Rodrigues, A.; Ropelewski, L.; RoyChowdhury, S.; Ryu, G.; Ryu, M. S.; Safonov, A.; Salva, S.; Saviano, G.; Sharma, A.; Sharma, A.; Sharma, R.; Shah, A. H.; Shopova, M.; Sturdy, J.; Sultanov, G.; Swain, S. K.; Szillasi, Z.; Talvitie, J.; Tatarinov, A.; Tuuva, T.; Tytgat, M.; Vai, I.; Van Stenis, M.; Venditti, R.; Verhagen, E.; Verwilligen, P.; Vitulo, P.; Volkov, S.; Vorobyev, A.; Wang, D.; Wang, M.; Yang, U.; Yang, Y.; Yonamine, R.; Zaganidis, N.; Zenoni, F.; Zhang, A.

    2018-02-01

    The CMS Collaboration plans to equip the very forward muon system with triple-GEM detectors that can withstand the environment of the High-Luminosity LHC. This project is at the final stages of R&D and moving to production. An unprecedented large area of several 100 m2 are to be instrumented with GEM detectors which will be produced in six different sites around the world. A common construction and quality control procedure is required to ensure the performance of each detector. The quality control steps will include optical inspection, cleaning and baking of all materials and parts used to build the detector, leakage current tests of the GEM foils, high voltage tests, gas leak tests of the chambers and monitoring pressure drop vs. time, gain calibration to know the optimal operation region of the detector, gain uniformity tests, and studying the efficiency, noise and tracking performance of the detectors in a cosmic stand using scintillators.

  5. Operational experience of a large area x-ray camera for protein crystallography

    International Nuclear Information System (INIS)

    Joachimiak, A.; Jorden, A. R.; Loeffen, P. W.; Naday, I.; Sanishvili, R.; Westbrook, E. M.

    1999-01-01

    After 3 years experience of operating very large area (210mm x 210mm) CCD-based detectors at the Advanced Photon Source, operational experience is reported. Four such detectors have been built, two for Structural Biology Center (APS-1 and SBC-2), one for Basic Energy Sciences Synchrotrons Radiation Center (Gold-2) at Argonne National Laboratory's Advanced Photon Source and one for Osaka University by Oxford Instruments, for use at Spring 8 (PX-21O). The detector is specifically designed as a high resolution and fast readout camera for macromolecular crystallography. Design trade-offs for speed and size are reviewed in light of operational experience and future requirements are considered. Operational data and examples of crystallography data are presented, together with plans for more development

  6. Large-area fabrication of patterned ZnO-nanowire arrays using light stamping lithography.

    Science.gov (United States)

    Hwang, Jae K; Cho, Sangho; Seo, Eun K; Myoung, Jae M; Sung, Myung M

    2009-12-01

    We demonstrate selective adsorption and alignment of ZnO nanowires on patterned poly(dimethylsiloxane) (PDMS) thin layers with (aminopropyl)siloxane self-assembled monolayers (SAMs). Light stamping lithography (LSL) was used to prepare patterned PDMS thin layers as neutral passivation regions on Si substrates. (3-Aminopropyl)triethoxysilane-based SAMs were selectively formed only on regions exposing the silanol groups of the Si substrates. The patterned positively charged amino groups define and direct the selective adsorption of ZnO nanowires with negative surface charges in the protic solvent. This procedure can be adopted in automated printing machines that generate patterned ZnO-nanowire arrays on large-area substrates. To demonstrate its usefulness, the LSL method was applied to prepare ZnO-nanowire transistor arrays on 4-in. Si wafers.

  7. Development of large-area silicon photomultiplier detectors for PET applications at FBK

    Energy Technology Data Exchange (ETDEWEB)

    Zorzi, Nicola, E-mail: zorzi@fbk.eu [Fondazione Bruno Kessler (FBK), Via Sommarive 18, I-38123 Trento Povo (Italy); Melchiorri, Mirko; Piazza, Alessandro; Piemonte, Claudio; Tarolli, Alessandro [Fondazione Bruno Kessler (FBK), Via Sommarive 18, I-38123 Trento Povo (Italy)

    2011-04-21

    This paper reports on the development of large-area silicon photomultiplier (SiPM) detectors specifically designed for positron emission tomography (PET) instruments. The sensors under study are monolithic arrays of two different types: a 2x2 array of {approx}4x4 mm{sup 2} elements and an 8x8 array of 1.5x1.5 mm{sup 2} pixels. These devices are characterized at wafer level by means of an automatic test procedure, consisting of current-voltage curves in forward and reverse bias. The tests allowed selection of functioning devices and evaluation of the uniformity of basic parameters. Results of the electrical characterization are reported showing that acceptable values of yield together with rather uniform distribution of parameters have been obtained. Reliability of produced SiPMs has been proved by long-term accelerated stress tests.

  8. Development of large-area silicon photomultiplier detectors for PET applications at FBK

    International Nuclear Information System (INIS)

    Zorzi, Nicola; Melchiorri, Mirko; Piazza, Alessandro; Piemonte, Claudio; Tarolli, Alessandro

    2011-01-01

    This paper reports on the development of large-area silicon photomultiplier (SiPM) detectors specifically designed for positron emission tomography (PET) instruments. The sensors under study are monolithic arrays of two different types: a 2x2 array of ∼4x4 mm 2 elements and an 8x8 array of 1.5x1.5 mm 2 pixels. These devices are characterized at wafer level by means of an automatic test procedure, consisting of current-voltage curves in forward and reverse bias. The tests allowed selection of functioning devices and evaluation of the uniformity of basic parameters. Results of the electrical characterization are reported showing that acceptable values of yield together with rather uniform distribution of parameters have been obtained. Reliability of produced SiPMs has been proved by long-term accelerated stress tests.

  9. The on-orbit calibration of the Fermi Large Area Telescope

    International Nuclear Information System (INIS)

    Ackermann, M.; Ajello, M.; Bartelt, J.; Bechtol, K.; Berenji, B.; Bloom, E.D.; Bogart, J.R.; Borgland, A.W.; Bouvier, A.; Cameron, R.A.; Campell, M.; Charles, E.; Chiang, J.; Claus, R.; Condamoor, S.; Digel, S.W.; Silva, E.D.E.; Drell, P.S.; Dubois, R.; Edmonds, Y.; Flath, D.L.; Focke, W.B.; Fouts, K.; Freytag, D.; Funk, S.; Glanzman, T.; Godfrey, G.; Goodman, J.; Hakimi, M.; Haller, G.; Hart, P.A.; Huffer, M.; Johannesson, G.; Johnson, A.S.; Kamae, T.; Kavelaars, A.; Kelly, H.; Kocian, M.L.; Lee, S.H.; Madejski, G.M.; Michelson, P.F.; Mitra, P.; Mitthumsiri, W.; Monzani, M.E.; Moskalenko, I.V.; Murgia, S.; Nelson, D.; Nolan, P.L.; Paneque, D.; Panetta, J.H.; Rochester, L.S.; Romani, R.W.; Sapozhnikov, L.; Saxton, O.H.; Sugizaki, M.; Tajima, H.; Tanaka, T.; Thayer, J.B.; Thayer, J.G.; Tramacere, A.; Turri, M.; Usher, T.L.; Wai, L.L.; Waite, A.P.; Wang, P.; Ackermann, M.; Ajello, M.; Bartelt, J.; Bechtol, K.; Berenji, B.; Bloom, E.D.; Bogart, J.R.; Borgland, A.W.; Bouvier, A.; Cameron, R.A.; Campell, M.; Charles, E.; Chiang, J.; Claus, R.; Condamoor, S.; Digel, S.W.; Silva, E.D.E.; Drell, P.S.; Dubois, R.; Edmonds, Y.; Flath, D.L.; Focke, W.B.; Fouts, K.; Freytag, D.; Funk, S.; Glanzman, T.; Godfrey, G.; Goodman, J.; Hakimi, M.; Haller, G.; Hart, P.A.; Huffer, M.; Johannesson, G.; Johnson, A.S.; Kamae, T.; Kavelaars, A.; Kelly, H.; Kocian, M.L.; Lee, S.H.; Madejski, G.M.; Michelson, P.F.; Mitra, P.; Mitthumsiri, W.; Monzani, M.E.; Moskalenko, I.V.; Murgia, S.; Nelson, D.; Nolan, P.L.; Paneque, D.; Panetta, J.H.; Rochester, L.S.; Romani, R.W.; Sapozhnikov, L.; Saxton, O.H.; Sugizaki, M.; Tajima, H.; Tanaka, T.; Thayer, J.B; Thayer, J.G.; Tramacere, A.; Turri, M.; Usher, T.L.; Wai, L.L.; Waite, A.P.; Wang, P.; Abdo, A.A.; Ampe, J.; Chekhtman, A.; Dermer, C.D.; Fewtrell, Z.; Grove, J.E.; Johnson, W.N.; Leas, B.; Lovellette, M.N.; Makeev, A.; May, D.; Raynor, W.; Strickman, M.S.; Wood, D.L.; Wood, K.S.; Abdo, A.A.; Anderson, B.; Atwood, W.B.; Dormody, M.; Johnson, R.P.; Porter, T.A.; Sadrozinski, H.F.W.; Parkinson, P.M.S.; Ziegler, M.; Anderson, B.; Atwood, W.B.; Dormody, M.; Johnson, R.P.; Porter, T.A.; Sadrozinski, H.F.W.; Parkinson, P.M.S.; Ziegler, M.; Axelsson, M.; Axelsson, M.; Carlson, P.; Conrad, J.; Klamra, W.; McGlynn, S.; Meurer, C.; Ryde, F.; Sellerholm, A.; Ylinen, T.; Bagagli, R.; Baldini, L.; Bellardi, F.; Bellazzini, R.; Bregeon, J.; Brez, A.; Ceccanti, M.; Fabiani, D.; Kuss, M.; Latronico, L.; Massai, M.M.; Minuti, M.; Omodei, N.; Pesce-Rollins, M.; Pinchera, M.; Rapposelli, E.; Razzano, M.; Saggini, N.; Sgro, C.; Spandre, G.; Tenze, A.; Ballet, J.; Casandjian, J.M.; Grenier, I.A.; Starck, J.L.

    2009-01-01

    The Large Area Telescope (LAT) on-board the Fermi Gamma-ray Space Telescope began its on-orbit operations on June 23, 2008. Calibrations, defined in a generic sense, correspond to synchronization of trigger signals, optimization of delays for latching data, determination of detector thresholds, gains and responses, evaluation of the perimeter of the South Atlantic Anomaly (SAA), measurements of live time, of absolute time, and internal and spacecraft bore-sight alignments. Here we describe on-orbit calibration results obtained using known astrophysical sources, galactic cosmic rays, and charge injection into the front-end electronics of each detector. Instrument response functions will be described in a separate publication. This paper demonstrates the stability of calibrations and describes minor changes observed since launch. These results have been used to calibrate the LAT datasets to be publicly released in August 2009. (authors)

  10. Terahertz Focusing and Polarization Control in Large-Area Bias-Free Semiconductor Emitters

    Science.gov (United States)

    Carthy, Joanna L.; Gow, Paul C.; Berry, Sam A.; Mills, Ben; Apostolopoulos, Vasilis

    2018-03-01

    We show that, when large-area multiplex terahertz semiconductor emitters, that work on diffusion currents and Schottky potentials, are illuminated by ultrashort optical pulses they can radiate a directional electromagnetic terahertz pulse which is controlled by the angular spectrum of the incident optical beam. Using the lens that focuses the incident near-infrared pulse, we have demonstrated THz emission focusing in free space, at the same point where the optical radiation would focus. We investigated the beam waist and Gouy phase shift of the THz emission as a function of frequency. We also show that the polarization profile of the emitted THz can be tailored by the metallic patterning on the semiconductor, demonstrating radial polarization when a circular emitter design is used. Our techniques can be used for fast THz beam steering and mode control for efficiently coupling to waveguides without the need for THz lenses or parabolic mirrors.

  11. Quality control for the first large areas of triple-GEM chambers for the CMS endcaps

    Directory of Open Access Journals (Sweden)

    Abbaneo D.

    2018-01-01

    Full Text Available The CMS Collaboration plans to equip the very forward muon system with triple-GEM detectors that can withstand the environment of the High-Luminosity LHC. This project is at the final stages of R&D and moving to production. An unprecedented large area of several 100 m2 are to be instrumented with GEM detectors which will be produced in six different sites around the world. A common construction and quality control procedure is required to ensure the performance of each detector. The quality control steps will include optical inspection, cleaning and baking of all materials and parts used to build the detector, leakage current tests of the GEM foils, high voltage tests, gas leak tests of the chambers and monitoring pressure drop vs. time, gain calibration to know the optimal operation region of the detector, gain uniformity tests, and studying the efficiency, noise and tracking performance of the detectors in a cosmic stand using scintillators.

  12. A compact system for large-area thermal nanoimprint lithography using smart stamps

    International Nuclear Information System (INIS)

    Pedersen, R H; Hansen, O; Kristensen, A

    2008-01-01

    We present a simple apparatus for thermal nanoimprint lithography. In this work, the stamp is designed to significantly reduce the requirements for pressure application on the external imprint system. By MEMS-based processing, an air cavity inside the stamp is created, and the required pressure for successful imprint is reduced. Additionally, the stamp is capable of performing controlled demolding after imprint. Due to the complexity of the stamp, a compact and cost-effective imprint apparatus can be constructed. The design and fabrication of the advanced stamp as well as the simple imprint equipment is presented. Test imprints of micrometer- and nanometer-scale structures are performed and characterized with respect to uniformity across a large area (35 mm radius). State-of-the-art uniformity for µm-scale features is demonstrated

  13. Implementation of large area CMOS image sensor module using the precision align inspection

    International Nuclear Information System (INIS)

    Kim, Byoung Wook; Kim, Toung Ju; Ryu, Cheol Woo; Lee, Kyung Yong; Kim, Jin Soo; Kim, Myung Soo; Cho, Gyu Seong

    2014-01-01

    This paper describes a large area CMOS image sensor module Implementation using the precision align inspection program. This work is needed because wafer cutting system does not always have high precision. The program check more than 8 point of sensor edges and align sensors with moving table. The size of a 2×1 butted CMOS image sensor module which except for the size of PCB is 170 mm×170 mm. And the pixel size is 55 μm×55 μm and the number of pixels is 3,072×3,072. The gap between the two CMOS image sensor module was arranged in less than one pixel size

  14. Evaluation of surface contamination due to alpha using large area contamination monitors

    International Nuclear Information System (INIS)

    Raghavayya, M.

    1998-01-01

    Radioactive contamination at work places is evaluated routinely using either the swipe sampling technique or a contamination monitor. Commercially available alpha probes used for the purpose are usually circular and have a face diameter of 50 or 100 mm. Square faced probes are also available. A thin aluminized mylar membrane of thickness 0.45 to 0.9 mg.cm -2 is used to screen the phosphor in the alpha probe to protect it from external light. The membrane cuts off more alphas from low energy emitters than from higher energy alpha emitters. Moreover the response of the detector for alphas originating at all points under the detector face is not uniform, especially when the large area alpha monitors are used. These factors can introduce errors as high as 40% into the measurements. This paper aims to quantify these errors and describe a procedure to overcome the limitations. (author)

  15. A large area position-sensitive ionization chamber for heavy-ion-induced reaction studies

    CERN Document Server

    Pant, L M; Dinesh, B V; Thomas, R G; Saxena, A; Sawant, Y S; Choudhury, R K

    2002-01-01

    A large area position-sensitive ionization chamber with a wide dynamic range has been developed to measure the mass, charge and energy of the heavy ions and the fission fragments produced in heavy-ion-induced reactions. The split anode geometry of the detector makes it suitable for both particle identification and energy measurements for heavy ions and fission fragments. The detector has been tested with alpha particles from sup 2 sup 4 sup 1 Am- sup 2 sup 3 sup 9 Pu source, fission fragments from sup 2 sup 5 sup 2 Cf and the heavy-ion beams from the 14UD Mumbai Pelletron accelerator facility. Using this detector, measurements on mass and total kinetic energy distributions in heavy-ion-induced fusion-fission reactions have been carried out for a wide range of excitation energies. Results on deep inelastic collisions and mass-energy correlations on different systems using this detector setup are discussed.

  16. Large area nano-patterning /writing on gold substrate using dip - pen nanolithography (DPN)

    Science.gov (United States)

    Saini, Sudhir Kumar; Vishwakarma, Amit; Agarwal, Pankaj B.; Pesala, Bala; Agarwal, Ajay

    2014-10-01

    Dip Pen Nanolithography (DPN) is utilized to pattern large area (50μmX50μm) gold substrate for application in fabricating Nano-gratings. For Nano-writing 16-MHA ink coated AFM tip was prepared using double dipping procedure. Gold substrate is fabricated on thermally grown SiO2 substrate by depositing ˜5 nm titanium layer followed by ˜30nm gold using DC pulse sputtering. The gratings were designed using period of 800nm and 25% duty cycle. Acquired AFM images indicate that as the AFM tip proceeds for nano-writing, line width decreases from 190nm to 100nm. This occurs probably due to depreciation of 16-MHA molecules in AFM tip as writing proceeds.

  17. FERMI LARGE AREA TELESCOPE DETECTION OF THE YOUNG SUPERNOVA REMNANT TYCHO

    International Nuclear Information System (INIS)

    Giordano, F.; Naumann-Godo, M.; Ballet, J.; Bechtol, K.; Funk, S.; Lande, J.; Tanaka, T.; Uchiyama, Y.; Mazziotta, M. N.; Rainò, S.; Tibolla, O.

    2012-01-01

    After almost three years of data taking in sky-survey mode, the Fermi Large Area Telescope has detected γ-ray emission toward Tycho's supernova remnant (SNR). The Tycho SNR is among the youngest remnants in the Galaxy, originating from a Type Ia Supernova in AD 1572. The γ-ray integral flux from 400 MeV up to 100 GeV has been measured to be (3.5 ± 1.1 stat ± 0.7 syst )× 10 –9 cm –2 s –1 with a photon index of 2.3 ± 0.2 stat ± 0.1 syst . A simple model consistent with TeV, X-ray, and radio data is sufficient to explain the observed emission as originating from π 0 decays as a result of cosmic-ray acceleration and interaction with the ambient medium.

  18. Ion flux nonuniformities in large-area high-frequency capacitive discharges

    International Nuclear Information System (INIS)

    Perret, A.; Chabert, P.; Booth, J.-P.; Jolly, J.; Guillon, J.; Auvray, Ph.

    2003-01-01

    Strong nonuniformities of plasma production are expected in capacitive discharges if the excitation wavelength becomes comparable to the reactor size (standing-wave effect) and/or if the plasma skin depth becomes comparable to the plate separation (skin effect) [M. A. Lieberman et al., Plasma Sources Sci. Technol. 11, 283 (2002)]. Ion flux uniformity measurements were carried out in a large-area square (40 cmx40 cm) capacitive discharge driven at frequencies between 13.56 MHz and 81.36 MHz in argon gas at 150 mTorr. At 13.56 MHz, the ion flux was uniform to ±5%. At 60 MHz (and above) and at low rf power, the standing-wave effect was seen (maximum of the ion flux at the center), in good quantitative agreement with theory. At higher rf power, maxima of the ion flux were observed at the edges, due either to the skin effect or to other edge effects

  19. A Population of Gamma-Ray Millisecond Pulsars Seen with the Fermi Large Area Telescope

    International Nuclear Information System (INIS)

    Dumora, D.; Grondin, M.H.; Guillemot, L.; Lemoine-Goumard, M.; Lovellette, M.N.; Parent, D.; Smith, D.A.; Abdo, A.A.; Chekhtman, A.; Dermer, C.D.; Grove, J.E.; Johnson, W.N.; Makeev, A.; Ray, P.S.; Strickman, M.S.; Wood, K.S.; Ackermann, M.; Ajello, M.; Bechtol, K.; Berenji, B.; Blandford, R.D.; Bloom, E.D.; Borgland, A.W.; Cameron, R.A.; Charles, E.; Chiang, J.; Claus, R.; Digel, S.W.; Silva, E.D.E.; Drell, P.S.; Dubois, R.; Edmonds, Y.; Focke, W.B.; Funk, S.; Glanzman, T.; Godfrey, G.; Hayashida, M.; Johannesson, G.; Kocian, M.L.; Lande, J.; Madejski, G.M.; Michelson, P.F.; Mitthumsiri, W.; Monzani, M.E.; Moskalenko, I.V.; Murgia, S.; Nolan, P.L.; Paneque, D.; Panetta, J.H.; Reimer, A.; Reimer, O.; Rochester, L.S.; Romani, R.W.; Tajima, H.; Tanaka, T.; Thayer, J.B.; Thayer, J.G.; Tramacere, A.; Uchiyama, Y.; Usher, T.L.; Van Etten, A.; Waite, A.P.; Wang, P.; Watters, K.; Atwood, W.B.; Dormody, M.; Johnson, R.P.; Porter, T.A.; Sadrozinski, H.F.W.; Schalk, T.L.; Thorsett, S.E.; Ziegler, M.; Axelsson, M.; Carlson, P.; Conrad, J.; Meurer, C.; Ryde, F.; Ylinen, T.; Axelsson, M.; Baldini, L.; Bellazzini, R.; Bregeon, J.; Brez, A.; Kuss, M.; Latronico, L.; Omodei, N.; Pesce-Rollins, M.; Razzano, M.; Sgro, C.; Spandre, G.; Ballet, J.; Casandjian, J.M.; Grenier, I.A.; Starck, J.L.

    2009-01-01

    Pulsars are born with sub-second spin periods and slow by electromagnetic braking for several tens of millions of years, when detectable radiation ceases. A second life can occur for neutron stars in binary systems. They can acquire mass and angular momentum from their companions, to be spun up to millisecond periods and begin radiating again. We searched Fermi Large Area Telescope data for pulsations from all known millisecond pulsars (MSPs) outside of globular clusters, using rotation parameters from radio telescopes. Strong gamma-ray pulsations were detected for eight MSPs. The gamma-ray pulse profiles and spectral properties resemble those of young gamma-ray pulsars. The basic emission mechanism seems to be the same for MSPs and young pulsars, with the emission originating in regions far from the neutron star surface. (authors)

  20. Superparamagnetic microbead transport induced by a magnetic field on large-area magnetic antidot arrays

    Science.gov (United States)

    Ouk, Minae; Beach, Geoffrey S. D.

    2017-12-01

    A method is presented for directed transport of superparamagnetic microbeads (SPBs) on magnetic antidot patterned substrates by applying a rotating elliptical magnetic field. We find a critical frequency for transport, beyond which the bead dynamics transitions from stepwise locomotion to local oscillation. We also find that the out-of-plane (HOOP) and in-plane (HIP) field magnitudes play crucial roles in triggering bead motion. Namely, we find threshold values in HOOP and HIP that depend on bead size, which can be used to independently and remotely address specific bead populations in a multi-bead mixture. These behaviors are explained in terms of the dynamic potential energy lansdscapes computed from micromagnetic simulations of the substrate magnetization configuration. Finally, we show that large-area magnetic patterns suitable for particle transport and sorting can be fabricated through a self-assembly lithography technique, which provides a simple, cost-effective means to integrate magnetic actuation into microfluidic systems.

  1. Implementation of large area CMOS image sensor module using the precision align inspection

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Byoung Wook; Kim, Toung Ju; Ryu, Cheol Woo [Radiation Imaging Technology Center, JBTP, Iksan (Korea, Republic of); Lee, Kyung Yong; Kim, Jin Soo [Nano Sol-Tech INC., Iksan (Korea, Republic of); Kim, Myung Soo; Cho, Gyu Seong [Dept. of Nuclear and Quantum Engineering, KAIST, Daejeon (Korea, Republic of)

    2014-12-15

    This paper describes a large area CMOS image sensor module Implementation using the precision align inspection program. This work is needed because wafer cutting system does not always have high precision. The program check more than 8 point of sensor edges and align sensors with moving table. The size of a 2×1 butted CMOS image sensor module which except for the size of PCB is 170 mm×170 mm. And the pixel size is 55 μm×55 μm and the number of pixels is 3,072×3,072. The gap between the two CMOS image sensor module was arranged in less than one pixel size.

  2. The On-Orbit Calibrations for the Fermi Large Area Telescope

    Energy Technology Data Exchange (ETDEWEB)

    Abdo, Aous A.; /Naval Research Lab, Wash., D.C.; Ackermann, M.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Ajello, M.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Ampe, J.; /Naval Research Lab, Wash., D.C.; Anderson, B.; /UC, Santa Cruz; Atwood, W.B.; /UC, Santa Cruz; Axelsson, M.; /Stockholm U., OKC /Stockholm U.; Bagagli, R.; /INFN, Pisa; Baldini, L.; /INFN, Pisa; Ballet, J.; /DAPNIA, Saclay; Barbiellini, Guido; /INFN, Trieste /Trieste U.; Bartelt, J.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bastieri, Denis; /INFN, Padua /Padua U.; Baughman, B.M.; /Ohio State U.; Bechtol, K.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bederede, D.; /DAPNIA, Saclay; Bellardi, F.; /INFN, Pisa; Bellazzini, R.; /INFN, Pisa; Belli, F.; /Frascati /Rome U.,Tor Vergata; Berenji, B.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bisello, D.; /INFN, Padua /Padua U. /Garching, Max Planck Inst., MPE /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Ecole Polytechnique /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /INFN, Perugia /Perugia U. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /DAPNIA, Saclay /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /INFN, Pisa /INFN, Pisa /Bari U. /INFN, Bari /Ecole Polytechnique /Washington U., Seattle /INFN, Padua /Padua U. /Bari U. /INFN, Bari /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /IASF, Milan /IASF, Milan /Kalmar U. /Stockholm U., OKC /Royal Inst. Tech., Stockholm /DAPNIA, Saclay /ASDC, Frascati /INFN, Pisa /INFN, Perugia /Perugia U. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /George Mason U. /Naval Research Lab, Wash., D.C. /NASA, Goddard /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /DAPNIA, Saclay /NASA, Goddard /INFN, Perugia /Perugia U.; /more authors..

    2011-11-17

    The Large Area Telescope (LAT) on-board the Fermi Gamma-ray Space Telescope began its on-orbit operations on June 23, 2008. Calibrations, defined in a generic sense, correspond to synchronization of trigger signals, optimization of delays for latching data, determination of detector thresholds, gains and responses, evaluation of the perimeter of the South Atlantic Anomaly (SAA), measurements of live time, of absolute time, and internal and spacecraft boresight alignments. Here we describe on-orbit calibration results obtained using known astrophysical sources, galactic cosmic rays, and charge injection into the front-end electronics of each detector. Instrument response functions will be described in a separate publication. This paper demonstrates the stability of calibrations and describes minor changes observed since launch. These results have been used to calibrate the LAT datasets to be publicly released in August 2009.

  3. The Fermi Large Area Telescope as a cosmic-ray detector

    International Nuclear Information System (INIS)

    Sgrò, Carmelo

    2013-01-01

    The Fermi Large Area Telescope is an international observatory conceived to study high energy gamma-rays from the universe. It is designed to identify and reconstruct electromagnetic showers and it can collect cosmic-ray electrons and positrons thanks to its triggering and filtering capabilities. The Fermi LAT collaboration has published several results on charged cosmic rays. We measured the inclusive spectrum of electrons and positrons from 7 GeV to 1 TeV and searched for anisotropies in the electron incoming direction. We have recently published a measurement of cosmic-ray positron-only and electron-only spectra for energies between 20 GeV and 200 GeV exploiting the Earth's magnetic field as a charge separator. In this work we describe the techniques and capabilities of the LAT as a cosmic-ray detector and review the recent results and their interpretations. Prospects for future studies and observations will also be discussed

  4. Large-area, high-intensity PV arrays for systems using dish concentrating optics

    Energy Technology Data Exchange (ETDEWEB)

    Ward, J.S.; Duda, A.; Zweibel, K.; Coutts, T.J. [National Renewable Energy Lab., Golden, CO (United States)

    1998-09-01

    In this paper, the authors report on efforts to fabricate monolithic interconnected modules (MIMs) using III-V semiconductors with bandgaps appropriate for the terrestrial solar spectrum. The small size of the component cells comprising the MIM allows for operation at extremely high flux densities and relaxes the requirement for a small spot size to be generated by the optics. This makes possible a PV option for the large dish concentrator systems that have been developed by the solar thermal community for use with Stirling engines. Additionally, the highly effective back-surface reflector integrated into the MIM design is an effective tool for thermal management of the array. Development of this technology would radically alter the projections for PV manufacturing capacity because of the potential for extremely high power generation per unit area of semiconductor material.

  5. Quality control for the first large areas of triple-GEM chambers for the CMS endcaps

    CERN Document Server

    AUTHOR|(CDS)2068936; Abbas, M.; Abbrescia, M.; Abi Akl, M.; Aboamer, O.; Acosta, D.; Ahmad, A.; Ahmed, W.; Aleksandrov, A.; Altieri, P.; Asawatangtrakuldee, C.; Aspell, P.; Assran, Y.; Awan, I.; Bally, S.; Ban, Y.; Banerjee, S.; Barashko, V.; Barria, P.; Bencze, G.; Beni, N.; Benussi, L.; Bhopatkar, V.; Bianco, S.; Bos, J.; Bouhali, O.; Braghieri, A.; Braibant, S.; Buontempo, S.; Calabria, C.; Caponero, M.; Caputo, C.; Cassese, F.; Castaneda, A.; Cauwenbergh, S.; Cavallo, F.R.; Celik, A.; Choi, M.; Choi, S.; Christiansen, J.; Cimmino, A.; Colafranceschi, S.; Colaleo, A.; Conde Garcia, A.; Czellar, S.; Dabrowski, M.M.; De Lentdecker, G.; De Oliveira, R.; de Robertis, G.; Dildick, S.; Dorney, B.; Endroczi, G.; Errico, F.; Fenyvesi, A.; Ferry, S.; Furic, I.; Giacomelli, P.; Gilmore, J.; Golovtsov, V.; Guiducci, L.; Guilloux, F.; Gutierrez, A.; Hadjiiska, R.M.; Hauser, J.; Hoepfner, K.; Hohlmann, M.; Hoorani, H.; Iaydjiev, P.; Jeng, Y.G.; Kamon, T.; Karchin, P.; Korytov, A.; Krutelyov, S.; Kumar, A.; Kim, H.; Lee, J.; Lenzi, T.; Litov, L.; Loddo, F.; Madorsky, A.; Maerschalk, T.; Maggi, M.; Magnani, A.; Mal, P.K.; Mandal, K.; Marchioro, A.; Marinov, A.; Majumdar, N.; Merlin, J.A.; Mitselmakher, G.; Mohanty, A.K.; Mohapatra, A.; Molnar, J.; Muhammad, S.; Mukhopadhyay, S.; Naimuddin, M.; Nuzzo, S.; Oliveri, E.; Pant, L.M.; Paolucci, P.; Park, I.; Passeggio, G.; Pavlov, B.; Philipps, B.; Piccolo, D.; Postema, H.; Puig Baranac, A.; Radi, A.; Radogna, R.; Raffone, G.; Ranieri, A.; Rashevski, G.; Riccardi, C.; Rodozov, M.; Rodrigues, A.; Ropelewski, L.; RoyChowdhury, S.; Ryu, G.; Ryu, M.S.; Safonov, A.; Salva, S.; Saviano, G.; Sharma, A.; Sharma, A.; Sharma, R.; Shah, A.H.; Shopova, M.; Sturdy, J.; Sultanov, G.; Swain, S.K.; Szillasi, Z.; Talvitie, J.; Tatarinov, A.; Tuuva, T.; Vai, I.; Van Stenis, M.; Venditti, R.; Verhagen, E.; Verwilligen, P.; Vitulo, P.; Volkov, S.; Vorobyev, A.; Wang, D.; Wang, M.; Yang, U.; Yang, Y.; Yonamine, R.; Zaganidis, N.; Zenoni, F.; Zhang, A.

    2015-01-01

    The CMS Collaboration plans to equip the very forward muon system with triple-GEM detectors that can withstand the environment of the High-Luminosity LHC. This project is at the final stages of R&D and moving to production. An unprecedented large area of several 100 m2 are to be instrumented with GEM detectors which will be produced in six different sites around the world. A common construction and quality control procedure is required to ensure the performance of each detector. The quality control steps will include optical inspection, cleaning and baking of all materials and parts used to build the detector, leakage current tests of the GEM foils, high voltage tests, gas leak tests of the chambers and monitoring pressure drop vs. time, gain calibration to know the optimal operation region of the detector, gain uniformity tests, and studying the efficiency, noise and tracking performance of the detectors in a cosmic stand using scintillators.

  6. The Potential of Unmanned Aerial Vehicle for Large Scale Mapping of Coastal Area

    International Nuclear Information System (INIS)

    Darwin, N; Ahmad, A; Zainon, O

    2014-01-01

    Many countries in the tropical region are covered with cloud for most of the time, hence, it is difficult to get clear images especially from high resolution satellite imagery. Aerial photogrammetry can be used but most of the time the cloud problem still exists. Today, this problem could be solved using a system known as unmanned aerial vehicle (UAV) where the aerial images can be acquired at low altitude and the system can fly under the cloud. The UAV system could be used in various applications including mapping coastal area. The UAV system is equipped with an autopilot system and automatic method known as autonomous flying that can be utilized for data acquisition. To achieve high resolution imagery, a compact digital camera of high resolution was used to acquire the aerial images at an altitude. In this study, the UAV system was employed to acquire aerial images of a coastal simulation model at low altitude. From the aerial images, photogrammetric image processing was executed to produce photogrammetric outputs such a digital elevation model (DEM), contour line and orthophoto. In this study, ground control point (GCP) and check point (CP) were established using conventional ground surveying method (i.e total station). The GCP is used for exterior orientation in photogrammetric processes and CP for accuracy assessment based on Root Mean Square Error (RMSE). From this study, it was found that the UAV system can be used for large scale mapping of coastal simulation model with accuracy at millimeter level. It is anticipated that the same system could be used for large scale mapping of real coastal area and produces good accuracy. Finally, the UAV system has great potential to be used for various applications that require accurate results or products at limited time and less man power

  7. Multi-layered fabrication of large area PDMS flexible optical light guide sheets

    Science.gov (United States)

    Green, Robert; Knopf, George K.; Bordatchev, Evgueni V.

    2017-02-01

    Large area polydimethylsiloxane (PDMS) flexible optical light guide sheets can be used to create a variety of passive light harvesting and illumination systems for wearable technology, advanced indoor lighting, non-planar solar light collectors, customized signature lighting, and enhanced safety illumination for motorized vehicles. These thin optically transparent micro-patterned polymer sheets can be draped over a flat or arbitrarily curved surface. The light guiding behavior of the optical light guides depends on the geometry and spatial distribution of micro-optical structures, thickness and shape of the flexible sheet, refractive indices of the constituent layers, and the wavelength of the incident light. A scalable fabrication method that combines soft-lithography, closed thin cavity molding, partial curing, and centrifugal casting is described in this paper for building thin large area multi-layered PDMS optical light guide sheets. The proposed fabrication methodology enables the of internal micro-optical structures (MOSs) in the monolithic PDMS light guide by building the optical system layer-by-layer. Each PDMS layer in the optical light guide can have the similar, or a slightly different, indices of refraction that permit total internal reflection within the optical sheet. The individual molded layers may also be defect free or micro-patterned with microlens or reflecting micro-features. In addition, the bond between adjacent layers is ensured because each layer is only partially cured before the next functional layer is added. To illustrate the scalable build-by-layers fabrication method a three-layer mechanically flexible illuminator with an embedded LED strip is constructed and demonstrated.

  8. Ross Sea Polynyas: Response of Ice Concentration Retrievals to Large Areas of Thin Ice

    Science.gov (United States)

    Kwok, R.; Comiso, J. C.; Martin, S.; Drucker, R.

    2007-01-01

    For a 3-month period between May and July of 2005, we examine the response of the Advanced Microwave Scanning Radiometer (AMSR-E) Enhanced NASA Team 2 (NT2) and AMSR-E Bootstrap (ABA) ice concentration algorithms to large areas of thin ice of the Ross Sea polynyas. Coincident Envisat Synthetic Aperture Radar (SAR) coverage of the region during this period offers a detailed look at the development of the polynyas within several hundred kilometers of the ice front. The high-resolution imagery and derived ice motion fields show bands of polynya ice, covering up to approximately 105 km(sup 2) of the Ross Sea, that are associated with wind-forced advection. In this study, ice thickness from AMSR-E 36 GHz polarization information serves as the basis for examination of the response. The quality of the thickness of newly formed sea ice (<10 cm) from AMSR-E is first assessed with thickness estimates derived from ice surface temperatures from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument. The effect of large areas of thin ice in lowering the ice concentration estimates from both NT2/ABA approaches is clearly demonstrated. Results show relatively robust relationships between retrieved ice concentrations and thin ice thickness estimates that differ between the two algorithms. These relationships define the approximate spatial coincidence of ice concentration and thickness isopleths. Using the 83% (ABA) and 91% (NT2) isopleths as polynya boundaries, we show that the computed coverage compares well with that using the estimated 10-cm thickness contour. The thin ice response characterized here suggests that in regions with polynyas, the retrieval results could be used to provide useful geophysical information, namely thickness and coverage.

  9. Inkjet printed large-area flexible circuits: a simple methodology for optimizing the printing quality

    Science.gov (United States)

    Cheng, Tao; Wu, Youwei; Shen, Xiaoqin; Lai, Wenyong; Huang, Wei

    2018-01-01

    In this work, a simple methodology was developed to enhance the patterning resolution of inkjet printing, involving process optimization as well as substrate modification and treatment. The line width of the inkjet-printed silver lines was successfully reduced to 1/3 of the original value using this methodology. Large-area flexible circuits with delicate patterns and good morphology were thus fabricated. The resultant flexible circuits showed excellent electrical conductivity as low as 4.5 Ω/□ and strong tolerance to mechanical bending. The simple methodology is also applicable to substrates with various wettability, which suggests a general strategy to enhance the printing quality of inkjet printing for manufacturing high-performance large-area flexible electronics. Project supported by the National Key Basic Research Program of China (Nos. 2014CB648300, 2017YFB0404501), the National Natural Science Foundation of China (Nos. 21422402, 21674050), the Natural Science Foundation of Jiangsu Province (Nos. BK20140060, BK20130037, BK20140865, BM2012010), the Program for Jiangsu Specially-Appointed Professors (No. RK030STP15001), the Program for New Century Excellent Talents in University (No. NCET-13-0872), the NUPT "1311 Project" and Scientific Foundation (Nos. NY213119, NY213169), the Synergetic Innovation Center for Organic Electronics and Information Displays, the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD), the Leading Talent of Technological Innovation of National Ten-Thousands Talents Program of China, the Excellent Scientific and Technological Innovative Teams of Jiangsu Higher Education Institutions (No. TJ217038), the Program for Graduate Students Research and Innovation of Jiangsu Province (No. KYZZ16-0253), and the 333 Project of Jiangsu Province (Nos. BRA2017402, BRA2015374).

  10. SCALES: SEVIRI and GERB CaL/VaL area for large-scale field experiments

    Science.gov (United States)

    Lopez-Baeza, Ernesto; Belda, Fernando; Bodas, Alejandro; Crommelynck, Dominique; Dewitte, Steven; Domenech, Carlos; Gimeno, Jaume F.; Harries, John E.; Jorge Sanchez, Joan; Pineda, Nicolau; Pino, David; Rius, Antonio; Saleh, Kauzar; Tarruella, Ramon; Velazquez, Almudena

    2004-02-01

    The main objective of the SCALES Project is to exploit the unique opportunity offered by the recent launch of the first European METEOSAT Second Generation geostationary satellite (MSG-1) to generate and validate new radiation budget and cloud products provided by the GERB (Geostationary Earth Radiation Budget) instrument. SCALES" specific objectives are: (i) definition and characterization of a large reasonably homogeneous area compatible to GERB pixel size (around 50 x 50 km2), (ii) validation of GERB TOA radiances and fluxes derived by means of angular distribution models, (iii) development of algorithms to estimate surface net radiation from GERB TOA measurements, and (iv) development of accurate methodologies to measure radiation flux divergence and analyze its influence on the thermal regime and dynamics of the atmosphere, also using GERB data. SCALES is highly innovative: it focuses on a new and unique space instrument and develops a new specific validation methodology for low resolution sensors that is based on the use of a robust reference meteorological station (Valencia Anchor Station) around which 3D high resolution meteorological fields are obtained from the MM5 Meteorological Model. During the 1st GERB Ground Validation Campaign (18th-24th June, 2003), CERES instruments on Aqua and Terra provided additional radiance measurements to support validation efforts. CERES instruments operated in the PAPS mode (Programmable Azimuth Plane Scanning) focusing the station. Ground measurements were taken by lidar, sun photometer, GPS precipitable water content, radiosounding ascents, Anchor Station operational meteorological measurements at 2m and 15m., 4 radiation components at 2m, and mobile stations to characterize a large area. In addition, measurements during LANDSAT overpasses on June 14th and 30th were also performed. These activities were carried out within the GIST (GERB International Science Team) framework, during GERB Commissioning Period.

  11. Large-area high-power VCSEL pump arrays optimized for high-energy lasers

    Science.gov (United States)

    Wang, Chad; Geske, Jonathan; Garrett, Henry; Cardellino, Terri; Talantov, Fedor; Berdin, Glen; Millenheft, David; Renner, Daniel; Klemer, Daniel

    2012-06-01

    Practical, large-area, high-power diode pumps for one micron (Nd, Yb) as well as eye-safer wavelengths (Er, Tm, Ho) are critical to the success of any high energy diode pumped solid state laser. Diode efficiency, brightness, availability and cost will determine how realizable a fielded high energy diode pumped solid state laser will be. 2-D Vertical-Cavity Surface-Emitting Laser (VCSEL) arrays are uniquely positioned to meet these requirements because of their unique properties, such as low divergence circular output beams, reduced wavelength drift with temperature, scalability to large 2-D arrays through low-cost and high-volume semiconductor photolithographic processes, high reliability, no catastrophic optical damage failure, and radiation and vacuum operation tolerance. Data will be presented on the status of FLIR-EOC's VCSEL pump arrays. Analysis of the key aspects of electrical, thermal and mechanical design that are critical to the design of a VCSEL pump array to achieve high power efficient array performance will be presented.

  12. Large rainfall changes consistently projected over substantial areas of tropical land

    Science.gov (United States)

    Chadwick, Robin; Good, Peter; Martin, Gill; Rowell, David P.

    2016-02-01

    Many tropical countries are exceptionally vulnerable to changes in rainfall patterns, with floods or droughts often severely affecting human life and health, food and water supplies, ecosystems and infrastructure. There is widespread disagreement among climate model projections of how and where rainfall will change over tropical land at the regional scales relevant to impacts, with different models predicting the position of current tropical wet and dry regions to shift in different ways. Here we show that despite uncertainty in the location of future rainfall shifts, climate models consistently project that large rainfall changes will occur for a considerable proportion of tropical land over the twenty-first century. The area of semi-arid land affected by large changes under a higher emissions scenario is likely to be greater than during even the most extreme regional wet or dry periods of the twentieth century, such as the Sahel drought of the late 1960s to 1990s. Substantial changes are projected to occur by mid-century--earlier than previously expected--and to intensify in line with global temperature rise. Therefore, current climate projections contain quantitative, decision-relevant information on future regional rainfall changes, particularly with regard to climate change mitigation policy.

  13. An Aerial-Ground Robotic System for Navigation and Obstacle Mapping in Large Outdoor Areas

    Directory of Open Access Journals (Sweden)

    David Zapata

    2013-01-01

    Full Text Available There are many outdoor robotic applications where a robot must reach a goal position or explore an area without previous knowledge of the environment around it. Additionally, other applications (like path planning require the use of known maps or previous information of the environment. This work presents a system composed by a terrestrial and an aerial robot that cooperate and share sensor information in order to address those requirements. The ground robot is able to navigate in an unknown large environment aided by visual feedback from a camera on board the aerial robot. At the same time, the obstacles are mapped in real-time by putting together the information from the camera and the positioning system of the ground robot. A set of experiments were carried out with the purpose of verifying the system applicability. The experiments were performed in a simulation environment and outdoor with a medium-sized ground robot and a mini quad-rotor. The proposed robotic system shows outstanding results in simultaneous navigation and mapping applications in large outdoor environments.

  14. THE SECOND FERMI LARGE AREA TELESCOPE CATALOG OF GAMMA-RAY PULSARS

    Energy Technology Data Exchange (ETDEWEB)

    Abdo, A. A. [Center for Earth Observing and Space Research, College of Science, George Mason University, Fairfax, VA 22030 (United States); Ajello, M. [Space Sciences Laboratory, 7 Gauss Way, University of California, Berkeley, CA 94720-7450 (United States); Allafort, A.; Bloom, E. D.; Bottacini, E. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Baldini, L. [Università di Pisa and Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Ballet, J. [Laboratoire AIM, CEA-IRFU/CNRS/Université Paris Diderot, Service d' Astrophysique, CEA Saclay, F-91191 Gif sur Yvette (France); Barbiellini, G. [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy); Baring, M. G. [Rice University, Department of Physics and Astronomy, MS-108, P.O. Box 1892, Houston, TX 77251 (United States); Bastieri, D. [Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy); Belfiore, A. [Santa Cruz Institute for Particle Physics, Department of Physics and Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States); Bellazzini, R.; Bregeon, J. [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Bhattacharyya, B. [National Centre for Radio Astrophysics, Tata Institute of Fundamental Research, Pune 411 007 (India); Bissaldi, E. [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, and Università di Trieste, I-34127 Trieste (Italy); Bonamente, E. [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, I-06123 Perugia (Italy); Brandt, T. J. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Brigida, M., E-mail: hartog@stanford.edu [Dipartimento di Fisica ' ' M. Merlin' ' dell' Università e del Politecnico di Bari, I-70126 Bari (Italy); and others

    2013-10-01

    This catalog summarizes 117 high-confidence ≥0.1 GeV gamma-ray pulsar detections using three years of data acquired by the Large Area Telescope (LAT) on the Fermi satellite. Half are neutron stars discovered using LAT data through periodicity searches in gamma-ray and radio data around LAT unassociated source positions. The 117 pulsars are evenly divided into three groups: millisecond pulsars, young radio-loud pulsars, and young radio-quiet pulsars. We characterize the pulse profiles and energy spectra and derive luminosities when distance information exists. Spectral analysis of the off-peak phase intervals indicates probable pulsar wind nebula emission for four pulsars, and off-peak magnetospheric emission for several young and millisecond pulsars. We compare the gamma-ray properties with those in the radio, optical, and X-ray bands. We provide flux limits for pulsars with no observed gamma-ray emission, highlighting a small number of gamma-faint, radio-loud pulsars. The large, varied gamma-ray pulsar sample constrains emission models. Fermi's selection biases complement those of radio surveys, enhancing comparisons with predicted population distributions.

  15. Photoresponse properties of large area MoS2 metal–semiconductor–metal photodetectors

    Science.gov (United States)

    Ko, Tsung-Shine; Huang, Yu-Jen; Lin, Der-Yuh; Lin, Chia-Feng; Hong, Bo-Syun; Chen, Hone-Zern

    2018-04-01

    In this study, a large-area molybdenum disulfide (MoS2) thin film was obtained by low pressure thermal sulfurization. Raman scattering spectrum shows that the peaks at 374 and 403 cm‑1 are from the MoS2 thin film. XRD result reveals peaks at 33 and 58.5° indicating MoS2(100) and (110) crystal planes. By using gold (Au), silver (Ag), and aluminum (Al) as contact materials on the MoS2 thin film, photoresponsivity results indicate that Ag is a suitable material for obtaining a high responsivity for a high-performance photodetector (PD). Photocurrent mapping measurements also reveal that Ag contacts have the best carrier transport characteristic with carrier diffusion length of 101 µm among these contacts. Furthermore, we investigated metal–semiconductor–metal MoS2 thin film PDs with interdigitated fingers of 300, 400, 500, and 600 µm contact widths, which showed that the large contact widths could produce a high photoresponse for PD application owing to low resistance.

  16. The importance of geoprocessing tools in radiometric monitoring of large areas

    Energy Technology Data Exchange (ETDEWEB)

    Dias, Danila Carrijo da Silva [Universidade Federal de Alfenas (UNIFAL), Pocos de Caldas, MG (Brazil); Comissao Nacional de Energia Nuclear (LAPOC/CNEN-MG), Pocos de Caldas, MG (Brazil). Lab. de Pocos de Caldas; Silva, Nivaldo Carlos da; Alberti, Heber Luiz Caponi; Guerrero, Eder Tadeu Zenun, E-mail: ncsilva@cnen.gov.b, E-mail: heber@cnen.gov.b, E-mail: edertzg@cnen.gov.b [Comissao Nacional de Energia Nuclear (LAPOC/CNEN-MG), Pocos de Caldas, MG (Brazil). Lab. de Pocos de Caldas

    2011-07-01

    Throughout history, the natural tendency of men to physically characterize their different surroundings has played an important role on the evolution of societies. Today, that tendency combined to the development of computer technologies, has allowed the accelerated growth of the Geographical Information Systems, which permits the analysis and manipulation of spatial data from diverse sources, producing geo referenced databases. The gamma radiation, one of the main contributors of human exposure to natural radiation, is known for its high penetration energy. Today, the environmental gamma radiation is measured through radiometric tracking mobile units, allowing large scale samplings and precise assessments. As a geo processing case study, a radiometric monitoring work was conducted in the town of Aguas da Prata-SP using a tracking mobile system, composed by a scintillator detector, a GPS and a computer, all installed in a vehicle. The data made of collected points and their respective doses and geographical references were captured and stored in a computer software and then inserted and treated in a GIS environment. After a cartographic base was created using a digitalized map of Aguas da Prata, the sampled points were plotted and interpolated with the cartographic base, producing two maps that demonstrate the tracking route and the gamma radiation dose range throughout the monitored area. Geo processing tools have shown great efficiency in this study, allowing agile manipulation and management of a large quantity of data, thus promoting a spatial analysis of natural radiation levels in the studied region. (author)

  17. Rapid monitoring of soil, smears, and air dusts by direct large-area alpha spectrometry

    International Nuclear Information System (INIS)

    Sill, C.W.

    1992-01-01

    Experimental conditions to permit rapid monitoring of soils, smears, and air dusts for transuranic (TRU) radionuclides under field conditions are described. The monitoring technique involves direct measurement of alpha emitters by alpha spectrometry using a large-area detector to identify and quantify the radionuclides present. The direct alpha spectrometry employs a circular gridded ionization chamber 35 cm in diameter which accommodates either a circular sample holder 25 cm in diameter or a rectangular one 20 by 25 cm (8 by 10 in.). Soils or settled dusts are finely ground, suspended in 30% ethanol, and sprayed onto a 25-cm stainless steel dish. Air dusts are collected with a high-volume sampler onto 20- by 25-cm membrane filters. Removable contamination is collected from surfaces onto a 20- by 25-cm filter using an 18-cm (7-in.) paint roller to hold the large filter in contact with the surface during sample collection. All three types of samples are then counted directly in the alpha spectrometer and no other sample preparation is necessary. Some results obtained are described

  18. Calibrating an optical scanner for quality assurance of large area radiation detectors

    Science.gov (United States)

    Karadzhinova, A.; Hildén, T.; Berdova, M.; Lauhakangas, R.; Heino, J.; Tuominen, E.; Franssila, S.; Hæggström, E.; Kassamakov, I.

    2014-11-01

    A gas electron multiplier (GEM) is a particle detector used in high-energy physics. Its main component is a thin copper-polymer-copper sandwich that carries Ø =70  ±  5 µm holes. Quality assurance (QA) is needed to guarantee both long operating life and reading fidelity of the GEM. Absence of layer defects and conformity of the holes to specifications is important. Both hole size and shape influence the detector’s gas multiplication factor and hence affect the collected data. For the scanner the required lateral measurement tolerance is ± 5 µm. We calibrated a high aspect ratio optical scanning system (OSS) to allow ensuring the quality of large GEM foils. For the calibration we microfabricated transfer standards, which were imaged with the OSS and which were compared to corresponding scanning electron microscopy (SEM) images. The calibration fulfilled the ISO/IEC 17025 and UKAS M3003 requirements: the calibration factor was 1.01  ±  0.01, determined at 95% confidence level across a 950  ×  950 mm2 area. The proposed large-scale scanning technique can potentially be valuable in other microfabricated products too.

  19. CONTEMPORANEOUS VLBA 5 GHz OBSERVATIONS OF LARGE AREA TELESCOPE DETECTED BLAZARS

    Energy Technology Data Exchange (ETDEWEB)

    Linford, J. D.; Taylor, G. B. [Department of Physics and Astronomy, University of New Mexico, MSC07 4220, Albuquerque, NM 87131-0001 (United States); Romani, R. W. [Department of Physics, Stanford University, Stanford, CA 94305 (United States); Helmboldt, J. F. [Naval Research Laboratory, Code 7213, 4555 Overlook Avenue SW, Washington, DC 20375 (United States); Readhead, A. C. S.; Reeves, R.; Richards, J. L. [Astronomy Department, California Institute of Technology, Mail Code 247-17, 1200 East California Boulevard, Pasadena, CA 91125 (United States)

    2012-01-10

    The radio properties of blazars detected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope have been observed contemporaneously by the Very Long Baseline Array (VLBA). In total, 232 sources were observed with the VLBA. Ninety sources that were previously observed as part of the VLBA Imaging and Polarimetry Survey (VIPS) have been included in the sample, as well as 142 sources not found in VIPS. This very large, 5 GHz flux-limited sample of active galactic nuclei (AGNs) provides insights into the mechanism that produces strong {gamma}-ray emission. In particular, we see that {gamma}-ray emission is related to strong, uniform magnetic fields in the cores of the host AGN. Included in this sample are non-blazar AGNs such as 3C84, M82, and NGC 6251. For the blazars, the total VLBA radio flux density at 5 GHz correlates strongly with {gamma}-ray flux. The LAT BL Lac objects tend to be similar to the non-LAT BL Lac objects, but the LAT flat-spectrum radio quasars (FSRQs) are significantly different from the non-LAT FSRQs. Strong core polarization is significantly more common among the LAT sources, and core fractional polarization appears to increase during LAT detection.

  20. CONTEMPORANEOUS VLBA 5 GHz OBSERVATIONS OF LARGE AREA TELESCOPE DETECTED BLAZARS

    International Nuclear Information System (INIS)

    Linford, J. D.; Taylor, G. B.; Romani, R. W.; Helmboldt, J. F.; Readhead, A. C. S.; Reeves, R.; Richards, J. L.

    2012-01-01

    The radio properties of blazars detected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope have been observed contemporaneously by the Very Long Baseline Array (VLBA). In total, 232 sources were observed with the VLBA. Ninety sources that were previously observed as part of the VLBA Imaging and Polarimetry Survey (VIPS) have been included in the sample, as well as 142 sources not found in VIPS. This very large, 5 GHz flux-limited sample of active galactic nuclei (AGNs) provides insights into the mechanism that produces strong γ-ray emission. In particular, we see that γ-ray emission is related to strong, uniform magnetic fields in the cores of the host AGN. Included in this sample are non-blazar AGNs such as 3C84, M82, and NGC 6251. For the blazars, the total VLBA radio flux density at 5 GHz correlates strongly with γ-ray flux. The LAT BL Lac objects tend to be similar to the non-LAT BL Lac objects, but the LAT flat-spectrum radio quasars (FSRQs) are significantly different from the non-LAT FSRQs. Strong core polarization is significantly more common among the LAT sources, and core fractional polarization appears to increase during LAT detection.

  1. Contemporaneous VLBA 5 GHz Observations of Large Area Telescope Detected Blazars

    Science.gov (United States)

    Linford, J. D.; Taylor, G. B.; Romani, R. W.; Helmboldt, J. F.; Readhead, A. C. S.; Reeves, R.; Richards, J. L.

    2012-01-01

    The radio properties of blazars detected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope have been observed contemporaneously by the Very Long Baseline Array (VLBA). In total, 232 sources were observed with the VLBA. Ninety sources that were previously observed as part of the VLBA Imaging and Polarimetry Survey (VIPS) have been included in the sample, as well as 142 sources not found in VIPS. This very large, 5 GHz flux-limited sample of active galactic nuclei (AGNs) provides insights into the mechanism that produces strong γ-ray emission. In particular, we see that γ-ray emission is related to strong, uniform magnetic fields in the cores of the host AGN. Included in this sample are non-blazar AGNs such as 3C84, M82, and NGC 6251. For the blazars, the total VLBA radio flux density at 5 GHz correlates strongly with γ-ray flux. The LAT BL Lac objects tend to be similar to the non-LAT BL Lac objects, but the LAT flat-spectrum radio quasars (FSRQs) are significantly different from the non-LAT FSRQs. Strong core polarization is significantly more common among the LAT sources, and core fractional polarization appears to increase during LAT detection.

  2. The second FERMI large area telescope catalog of gamma-ray pulsars

    Energy Technology Data Exchange (ETDEWEB)

    Abdo, A. A.; Ajello, M.; Allafort, A.; Baldini, L.; Ballet, J.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Belfiore, A.; Bellazzini, R.; Bhattacharyya, B.; Bissaldi, E.; Bloom, E. D.; Bonamente, E.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Burgay, M.; Burnett, T. H.; Busetto, G.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Camilo, F.; Caraveo, P. A.; Casandjian, J. M.; Cecchi, C.; Çelik, Ö.; Charles, E.; Chaty, S.; Chaves, R. C. G.; Chekhtman, A.; Chen, A. W.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cognard, I.; Cohen-Tanugi, J.; Cominsky, L. R.; Conrad, J.; Cutini, S.; D' Ammando, F.; de Angelis, A.; DeCesar, M. E.; De Luca, A.; den Hartog, P. R.; de Palma, F.; Dermer, C. D.; Desvignes, G.; Digel, S. W.; Di Venere, L.; Drell, P. S.; Drlica-Wagner, A.; Dubois, R.; Dumora, D.; Espinoza, C. M.; Falletti, L.; Favuzzi, C.; Ferrara, E. C.; Focke, W. B.; Franckowiak, A.; Freire, P. C. C.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Germani, S.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Gotthelf, E. V.; Grenier, I. A.; Grondin, M. -H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Hadasch, D.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hays, E.; Hessels, J.; Hewitt, J.; Hill, A. B.; Horan, D.; Hou, X.; Hughes, R. E.; Jackson, M. S.; Janssen, G. H.; Jogler, T.; Jóhannesson, G.; Johnson, R. P.; Johnson, A. S.; Johnson, T. J.; Johnson, W. N.; Johnston, S.; Kamae, T.; Kataoka, J.; Keith, M.; Kerr, M.; Knödlseder, J.; Kramer, M.; Kuss, M.; Lande, J.; Larsson, S.; Latronico, L.; Lemoine-Goumard, M.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Lyne, A. G.; Manchester, R. N.; Marelli, M.; Massaro, F.; Mayer, M.; Mazziotta, M. N.; McEnery, J. E.; McLaughlin, M. A.; Mehault, J.; Michelson, P. F.; Mignani, R. P.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori, T.; Nemmen, R.; Nuss, E.; Ohno, M.; Ohsugi, T.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paneque, D.; Panetta, J. H.; Parent, D.; Perkins, J. S.; Pesce-Rollins, M.; Pierbattista, M.; Piron, F.; Pivato, G.; Pletsch, H. J.; Porter, T. A.; Possenti, A.; Rainò, S.; Rando, R.; Ransom, S. M.; Ray, P. S.; Razzano, M.; Rea, N.; Reimer, A.; Reimer, O.; Renault, N.; Reposeur, T.; Ritz, S.; Romani, R. W.; Roth, M.; Rousseau, R.; Roy, J.; Ruan, J.; Sartori, A.; Saz Parkinson, P. M.; Scargle, J. D.; Schulz, A.; Sgrò, C.; Shannon, R.; Siskind, E. J.; Smith, D. A.; Spandre, G.; Spinelli, P.; Stappers, B. W.; Strong, A. W.; Suson, D. J.; Takahashi, H.; Thayer, J. G.; Thayer, J. B.; Theureau, G.; Thompson, D. J.; Thorsett, S. E.; Tibaldo, L.; Tibolla, O.; Tinivella, M.; Torres, D. F.; Tosti, G.; Troja, E.; Uchiyama, Y.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Venter, C.; Vianello, G.; Vitale, V.; Wang, N.; Weltevrede, P.; Winer, B. L.; Wolff, M. T.; Wood, D. L.; Wood, K. S.; Wood, M.; Yang, Z.

    2013-09-19

    This catalog summarizes 117 high-confidence ≥0.1 GeV gamma-ray pulsar detections using three years of data acquired by the Large Area Telescope (LAT) on the Fermi satellite. Half are neutron stars discovered using LAT data through periodicity searches in gamma-ray and radio data around LAT unassociated source positions. The 117 pulsars are evenly divided into three groups: millisecond pulsars, young radio-loud pulsars, and young radio-quiet pulsars. We characterize the pulse profiles and energy spectra and derive luminosities when distance information exists. Spectral analysis of the off-peak phase intervals indicates probable pulsar wind nebula emission for four pulsars, and off-peak magnetospheric emission for several young and millisecond pulsars. We compare the gamma-ray properties with those in the radio, optical, and X-ray bands. We provide flux limits for pulsars with no observed gamma-ray emission, highlighting a small number of gamma-faint, radio-loud pulsars. The large, varied gamma-ray pulsar sample constrains emission models. Fermi's selection biases complement those of radio surveys, enhancing comparisons with predicted population distributions.

  3. The second fermi large area telescope catalog of gamma-ray pulsars

    Energy Technology Data Exchange (ETDEWEB)

    Abdo, A. A.; Ajello, M.; Allafort, A.; Baldini, L.; Ballet, J.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Belfiore, A.; Bellazzini, R.; Bhattacharyya, B.; Bissaldi, E.; Bloom, E. D.; Bonamente, E.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Burgay, M.; Burnett, T. H.; Busetto, G.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Camilo, F.; Caraveo, P. A.; Casandjian, J. M.; Cecchi, C.; Çelik, Ö.; Charles, E.; Chaty, S.; Chaves, R. C. G.; Chekhtman, A.; Chen, A. W.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cognard, I.; Cohen-Tanugi, J.; Cominsky, L. R.; Conrad, J.; Cutini, S.; D' Ammando, F.; de Angelis, A.; DeCesar, M. E.; De Luca, A.; den Hartog, P. R.; de Palma, F.; Dermer, C. D.; Desvignes, G.; Digel, S. W.; Di Venere, L.; Drell, P. S.; Drlica-Wagner, A.; Dubois, R.; Dumora, D.; Espinoza, C. M.; Falletti, L.; Favuzzi, C.; Ferrara, E. C.; Focke, W. B.; Franckowiak, A.; Freire, P. C. C.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Germani, S.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Gotthelf, E. V.; Grenier, I. A.; Grondin, M. -H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Hadasch, D.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hays, E.; Hessels, J.; Hewitt, J.; Hill, A. B.; Horan, D.; Hou, X.; Hughes, R. E.; Jackson, M. S.; Janssen, G. H.; Jogler, T.; Jóhannesson, G.; Johnson, R. P.; Johnson, A. S.; Johnson, T. J.; Johnson, W. N.; Johnston, S.; Kamae, T.; Kataoka, J.; Keith, M.; Kerr, M.; Knödlseder, J.; Kramer, M.; Kuss, M.; Lande, J.; Larsson, S.; Latronico, L.; Lemoine-Goumard, M.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Lyne, A. G.; Manchester, R. N.; Marelli, M.; Massaro, F.; Mayer, M.; Mazziotta, M. N.; McEnery, J. E.; McLaughlin, M. A.; Mehault, J.; Michelson, P. F.; Mignani, R. P.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori, T.; Nemmen, R.; Nuss, E.; Ohno, M.; Ohsugi, T.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paneque, D.; Panetta, J. H.; Parent, D.; Perkins, J. S.; Pesce-Rollins, M.; Pierbattista, M.; Piron, F.; Pivato, G.; Pletsch, H. J.; Porter, T. A.; Possenti, A.; Rainò, S.; Rando, R.; Ransom, S. M.; Ray, P. S.; Razzano, M.; Rea, N.; Reimer, A.; Reimer, O.; Renault, N.; Reposeur, T.; Ritz, S.; Romani, R. W.; Roth, M.; Rousseau, R.; Roy, J.; Ruan, J.; Sartori, A.; Saz Parkinson, P. M.; Scargle, J. D.; Schulz, A.; Sgrò, C.; Shannon, R.; Siskind, E. J.; Smith, D. A.; Spandre, G.; Spinelli, P.; Stappers, B. W.; Strong, A. W.; Suson, D. J.; Takahashi, H.; Thayer, J. G.; Thayer, J. B.; Theureau, G.; Thompson, D. J.; Thorsett, S. E.; Tibaldo, L.; Tibolla, O.; Tinivella, M.; Torres, D. F.; Tosti, G.; Troja, E.; Uchiyama, Y.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Venter, C.; Vianello, G.; Vitale, V.; Wang, N.; Weltevrede, P.; Winer, B. L.; Wolff, M. T.; Wood, D. L.; Wood, K. S.; Wood, M.; Yang, Z.

    2013-09-19

    This catalog summarizes 117 high-confidence ≥0.1 GeV gamma-ray pulsar detections using three years of data acquired by the Large Area Telescope (LAT) on the Fermi satellite. Half are neutron stars discovered using LAT data through periodicity searches in gamma-ray and radio data around LAT unassociated source positions. The 117 pulsars are evenly divided into three groups: millisecond pulsars, young radio-loud pulsars, and young radio-quiet pulsars. We characterize the pulse profiles and energy spectra and derive luminosities when distance information exists. Spectral analysis of the off-peak phase intervals indicates probable pulsar wind nebula emission for four pulsars, and off-peak magnetospheric emission for several young and millisecond pulsars. We compare the gamma-ray properties with those in the radio, optical, and X-ray bands. We provide flux limits for pulsars with no observed gamma-ray emission, highlighting a small number of gamma-faint, radio-loud pulsars. The large, varied gamma-ray pulsar sample constrains emission models. Fermi's selection biases complement those of radio surveys, enhancing comparisons with predicted population distributions.

  4. FERMI LARGE AREA TELESCOPE OBSERVATIONS OF PSR J1836+5925

    International Nuclear Information System (INIS)

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Borgland, A. W.; Atwood, W. B.; Belfiore, A.; Baldini, L.; Bellazzini, R.; Bregeon, J.; Brez, A.; Ballet, J.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Bonamente, E.; Brigida, M.

    2010-01-01

    The discovery of the γ-ray pulsar PSR J1836+5925, powering the formerly unidentified EGRET source 3EG J1835+5918, was one of the early accomplishments of the Fermi Large Area Telescope (LAT). Sitting 25 0 off the Galactic plane, PSR J1836+5925 is a 173 ms pulsar with a characteristic age of 1.8 million years, a spindown luminosity of 1.1 x 10 34 erg s -1 , and a large off-peak (OP) emission component, making it quite unusual among the known γ-ray pulsar population. We present an analysis of one year of LAT data, including an updated timing solution, detailed spectral results, and a long-term light curve showing no indication of variability. No evidence for a surrounding pulsar wind nebula is seen and the spectral characteristics of the OP emission indicate it is likely magnetospheric. Analysis of recent XMM-Newton observations of the X-ray counterpart yields a detailed characterization of its spectrum, which, like Geminga, is consistent with that of a neutron star showing evidence for both magnetospheric and thermal emission.

  5. Molecular beam epitaxy of large-area SnSe2 with monolayer thickness fluctuation

    Science.gov (United States)

    Park, Young Woon; Jerng, Sahng-Kyoon; Jeon, Jae Ho; Roy, Sanjib Baran; Akbar, Kamran; Kim, Jeong; Sim, Yumin; Seong, Maeng-Je; Kim, Jung Hwa; Lee, Zonghoon; Kim, Minju; Yi, Yeonjin; Kim, Jinwoo; Noh, Do Young; Chun, Seung-Hyun

    2017-03-01

    The interest in layered materials is largely based on the expectation that they will be beneficial for a variety of applications, from low-power-consuming, wearable electronics to energy harvesting. However, the properties of layered materials are highly dependent on thickness, and the difficulty of controlling thickness over a large area has been a bottleneck for commercial applications. Here, we report layer-by-layer growth of SnSe2, a layered semiconducting material, via van der Waals epitaxy. The films were fabricated on insulating mica substrates with substrate temperatures in the range of 210 °C-370 °C. The surface consists of a mixture of N and (N ± 1) layers, showing that the thickness of the film can be defined with monolayer accuracy (±0.6 nm). High-resolution transmission electron microscopy reveals a polycrystalline film with a grain size of ˜100 nm and clear Moiré patterns from overlapped grains with similar thickness. We also report field effect mobility values of 3.7 cm2 V-1 s-1 and 6.7 cm2 V-1 s-1 for 11 and 22 nm thick SnSe2, respectively. SnSe2 films with customizable thickness can provide valuable platforms for industry and academic researchers to fully exploit the potential of layered materials.

  6. Large-Area Neutron Detector based on Li-6 Pulse Mode Ionization Chamber

    International Nuclear Information System (INIS)

    Chung, K.; Ianakiev, K.D.; Swinhoe, M.T.; Makela, M.F.

    2005-01-01

    Prototypes of a Li-6 Pulse Mode Ionization Chamber (LiPMIC) have been in development for the past two years for the purpose of providing large-area neutron detector. this system would be suitable for remote deployment for homeland security and counterterrorism needs at borders, ports, and nuclear facilities. A prototype of LiPMIC is expected to provide a similar level of performance to the current industry-standard, He-3 proportional counters, while keeping the initial cost of procurement down by an order of magnitude, especially where large numbers of detectors are required. The overall design aspect and the efficiency optimization process is discussed. Specifically, the MCNP simulations of a single-cell prototype were performed and benchmarked with the experimental results. MCNP simulations of a three dimensional array design show intrinsic efficiency comparable to that of an array of He-3 proportional counters. LiPMIC has shown steady progress toward fulfilling the design expectations and future design modification and optimization are discussed.

  7. CARMA LARGE AREA STAR FORMATION SURVEY: OBSERVATIONAL ANALYSIS OF FILAMENTS IN THE SERPENS SOUTH MOLECULAR CLOUD

    Energy Technology Data Exchange (ETDEWEB)

    Fernández-López, M.; Looney, L.; Lee, K.; Segura-Cox, D. [Department of Astronomy, University of Illinois at Urbana—Champaign, 1002 West Green Street, Urbana, IL 61801 (United States); Arce, H. G.; Plunkett, A. [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520-8101 (United States); Mundy, L. G.; Storm, S.; Teuben, P. J.; Pound, M. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Isella, A.; Kauffmann, J. [Astronomy Department, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Tobin, J. J. [National Radio Astronomy Observatory, Charlottesville, VA 22903 (United States); Rosolowsky, E. [Departments of Physics and Statistics, University of British Columbia, Okanagan Campus, 3333 University Way, Kelowna, BC V1V 1V7 (Canada); Kwon, W. [SRON Netherlands Institute for Space Research, Landleven 12, 9747-AD Groningen (Netherlands); Ostriker, E. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Tassis, K. [Department of Physics and Institute of Theoretical and Computational Physics, University of Crete, P.O. Box 2208, GR-710 03 Heraklion, Crete (Greece); Shirley, Y. L., E-mail: manferna@gmail.com [Steward Observatory, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)

    2014-08-01

    We present the N{sub 2}H{sup +} (J = 1 → 0) map of the Serpens South molecular cloud obtained as part of the CARMA Large Area Star Formation Survey. The observations cover 250 arcmin{sup 2} and fully sample structures from 3000 AU to 3 pc with a velocity resolution of 0.16 km s{sup –1}, and they can be used to constrain the origin and evolution of molecular cloud filaments. The spatial distribution of the N{sub 2}H{sup +} emission is characterized by long filaments that resemble those observed in the dust continuum emission by Herschel. However, the gas filaments are typically narrower such that, in some cases, two or three quasi-parallel N{sub 2}H{sup +} filaments comprise a single observed dust continuum filament. The difference between the dust and gas filament widths casts doubt on Herschel ability to resolve the Serpens South filaments. Some molecular filaments show velocity gradients along their major axis, and two are characterized by a steep velocity gradient in the direction perpendicular to the filament axis. The observed velocity gradient along one of these filaments was previously postulated as evidence for mass infall toward the central cluster, but these kind of gradients can be interpreted as projection of large-scale turbulence.

  8. Honeycomblike large area LaB6 plasma source for Multi-Purpose Plasma facility

    International Nuclear Information System (INIS)

    Woo, Hyun-Jong; Chung, Kyu-Sun; You, Hyun-Jong; Lee, Myoung-Jae; Lho, Taihyeop; Choh, Kwon Kook; Yoon, Jung-Sik; Jung, Yong Ho; Lee, Bongju; Yoo, Suk Jae; Kwon, Myeon

    2007-01-01

    A Multi-Purpose Plasma (MP 2 ) facility has been renovated from Hanbit mirror device [Kwon et al., Nucl. Fusion 43, 686 (2003)] by adopting the same philosophy of diversified plasma simulator (DiPS) [Chung et al., Contrib. Plasma Phys. 46, 354 (2006)] by installing two plasma sources: LaB 6 (dc) and helicon (rf) plasma sources; and making three distinct simulators: divertor plasma simulator, space propulsion simulator, and astrophysics simulator. During the first renovation stage, a honeycomblike large area LaB 6 (HLA-LaB 6 ) cathode was developed for the divertor plasma simulator to improve the resistance against the thermal shock fragility for large and high density plasma generation. A HLA-LaB 6 cathode is composed of the one inner cathode with 4 in. diameter and the six outer cathodes with 2 in. diameter along with separate graphite heaters. The first plasma is generated with Ar gas and its properties are measured by the electric probes with various discharge currents and magnetic field configurations. Plasma density at the middle of central cell reaches up to 2.6x10 12 cm -3 , while the electron temperature remains around 3-3.5 eV at the low discharge current of less than 45 A, and the magnetic field intensity of 870 G. Unique features of electric property of heaters, plasma density profiles, is explained comparing with those of single LaB 6 cathode with 4 in. diameter in DiPS

  9. Development of a PSA-based Loss of Large Area Analysis Method

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Mee Jeong; Jung, Woosik [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kim, Myungsu [Korea Hydro Nuclear Power, Central Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    As a result of these initial post 9-11 assessments in 2002, the NRC issued an interim safeguards and security compensatory measures order. In 'Interim Compensatory Measures for High Threat Environment,'. Section B.5.b (not publically available) of this order, current NPP licensees had to adopt mitigation or restore reactor core cooling, containment, and spent fuel pool (SFP) cooling capabilities to cope with a LOLA due to large fires and explosions from any cause, including beyond-design basis threat(BDBT) aircraft impacts. In 2009, the NRC issued amendments to 10CFR Part 52, and Part 73 for power reactor security requirements for operating and new reactors. New U.S. licensed commercial nuclear power plant operators are required to provide a LOLA(Loss of Large Area) analysis as per the U.S. Code of Federal Regulations, 10CFR50.54(hh)(2). Additionally 10CFR52.80(d) provides the required submittal information on how an applicant for a combined operating license(COL) for a nuclear power plant to meet these requirements. It is necessary to prepare our own guidance for a development of LOLA strategies. In this paper, we proposed a method to look for interesting combinations of rooms in certain targets getting through VAI model, and produced insights that could be used to influence LOLA strategies.

  10. The importance of geoprocessing tools in radiometric monitoring of large areas

    International Nuclear Information System (INIS)

    Dias, Danila Carrijo da Silva; Comissao Nacional de Energia Nuclear; Silva, Nivaldo Carlos da; Alberti, Heber Luiz Caponi; Guerrero, Eder Tadeu Zenun

    2011-01-01

    Throughout history, the natural tendency of men to physically characterize their different surroundings has played an important role on the evolution of societies. Today, that tendency combined to the development of computer technologies, has allowed the accelerated growth of the Geographical Information Systems, which permits the analysis and manipulation of spatial data from diverse sources, producing geo referenced databases. The gamma radiation, one of the main contributors of human exposure to natural radiation, is known for its high penetration energy. Today, the environmental gamma radiation is measured through radiometric tracking mobile units, allowing large scale samplings and precise assessments. As a geo processing case study, a radiometric monitoring work was conducted in the town of Aguas da Prata-SP using a tracking mobile system, composed by a scintillator detector, a GPS and a computer, all installed in a vehicle. The data made of collected points and their respective doses and geographical references were captured and stored in a computer software and then inserted and treated in a GIS environment. After a cartographic base was created using a digitalized map of Aguas da Prata, the sampled points were plotted and interpolated with the cartographic base, producing two maps that demonstrate the tracking route and the gamma radiation dose range throughout the monitored area. Geo processing tools have shown great efficiency in this study, allowing agile manipulation and management of a large quantity of data, thus promoting a spatial analysis of natural radiation levels in the studied region. (author)

  11. Large area synthesis, characterization, and anisotropic etching of two dimensional tungsten disulfide films

    International Nuclear Information System (INIS)

    Mutlu, Zafer; Ozkan, Mihrimah; Ozkan, Cengiz S.

    2016-01-01

    Emergent properties of tungsten disulfide at the quantum confinement limit hold promise for electronic and optoelectronic applications. Here we report on the large area synthesis of atomically thin tungsten disulfide films with strong photoluminescence properties via sulfurization of the pre-deposited tungsten films. Detailed characterization of the pre-deposited tungsten films and tungsten disulfide films are performed using microscopy and spectroscopy methods. By directly heating tungsten disulfide films in air, we have shown that the films tend to be etched into a series of triangular shaped pits with the same orientations, revealing the anisotropic etching behavior of tungsten disulfide edges. Moreover, the dimensions of the triangular pits increase with the number of layers, suggesting a thickness dependent behavior of etching in tungsten disulfide films. This method offers a promising new avenue for engineering the edge structures of tungsten disulfide films. - Highlights: • Large-scale synthesis of WS_2 films is achieved via sulfurization of W films. • Annealing of W films leads to a substantial improvement in the quality of WS_2 films. • WS_2 films show laser power dependent photoluminescence characteristics. • WS_2 films are etched with well-oriented triangular pits upon annealing in air. • Anisotropic oxidative etching is greatly affected by the thickness of WS_2 films.

  12. Large area, low cost space solar cells with optional wraparound contacts

    Science.gov (United States)

    Michaels, D.; Mendoza, N.; Williams, R.

    1981-01-01

    Design parameters for two large area, low cost solar cells are presented, and electron irradiation testing, thermal alpha testing, and cell processing are discussed. The devices are a 2 ohm-cm base resistivity silicon cell with an evaporated aluminum reflector produced in a dielectric wraparound cell, and a 10 ohm-cm silicon cell with the BSF/BSR combination and a conventional contact system. Both cells are 5.9 x 5.9 cm and require 200 micron thick silicon material due to mission weight constraints. Normalized values for open circuit voltage, short circuit current, and maximum power calculations derived from electron radiation testing are given. In addition, thermal alpha testing values of absorptivity and emittance are included. A pilot cell processing run produced cells averaging 14.4% efficiencies at AMO 28 C. Manufacturing for such cells will be on a mechanized process line, and the area of coverslide application technology must be considered in order to achieve cost effective production.

  13. First observation of Cherenkov rings with a large area CsI-TGEM-based RICH prototype

    CERN Document Server

    Peskov, V; Di Mauro, A; Martinengo, P; Mayani, D; Molnar, L; Nappi, E; Paic, G; Smirnov, N; Anand, H; Shukla, I

    2012-01-01

    We have built a RICH detector prototype consisting of a liquid C6F14 radiator and six triple Thick Gaseous Electron Multipliers (TGEMs), each of them having an active area of 10x10 cm2. One triple TGEM has been placed behind the liquid radiator in order to detect the beam particles, whereas the other five have been positioned around the central one at a distance to collect the Cherenkov photons. The upstream electrode of each of the TGEM stacks has been coated with a 0.4 micron thick CsI layer. In this paper, we will present the results from a series of laboratory tests with this prototype carried out using UV light, 6 keV photons from 55Fe and electrons from 90Sr as well as recent results of tests with a beam of charged pions where for the first time Cherenkov Ring images have been successfully recorded with TGEM photodetectors. The achieved results prove the feasibility of building a large area Cherenkov detector consisting of a matrix of TGEMs.

  14. Ag paste-based nanomesh electrodes for large-area touch screen panels

    International Nuclear Information System (INIS)

    Chung, Sung-il; Kim, Pan Kyeom; Ha, Tae-gyu

    2017-01-01

    This study reports a novel method for fabricating a nickel nanomesh mold using phase shift lithography, suitable for use in large-area touch screen panel applications. Generally, the values of light transmittance and sheet resistance of metal mesh transparent conducting electrode (TCE) films are determined by the ratio of the aperture to metal areas. In this study, taking into consideration the optimal light transmittance, sheet resistance, and pattern visibility issues, the line width of the metal mesh pattern was ∼1 µ m, and the pitch of the pattern was ∼100 µ m. In addition, a novel method of manufacturing wiring electrodes using a phase shift lithography process was also developed and evaluated. A TCE film with a size of 370 mm  ×  470 mm was prepared and evaluated for its light transmittance and sheet resistance. In addition, wiring electrodes with a length of 70 mm were fabricated and their line resistances evaluated by varying their line width. (paper)

  15. Micro- and nanoscale electrical characterization of large-area graphene transferred to functional substrates

    Directory of Open Access Journals (Sweden)

    Gabriele Fisichella

    2013-04-01

    Full Text Available Chemical vapour deposition (CVD on catalytic metals is one of main approaches for high-quality graphene growth over large areas. However, a subsequent transfer step to an insulating substrate is required in order to use the graphene for electronic applications. This step can severely affect both the structural integrity and the electronic properties of the graphene membrane. In this paper, we investigated the morphological and electrical properties of CVD graphene transferred onto SiO2 and on a polymeric substrate (poly(ethylene-2,6-naphthalene dicarboxylate, briefly PEN, suitable for microelectronics and flexible electronics applications, respectively. The electrical properties (sheet resistance, mobility, carrier density of the transferred graphene as well as the specific contact resistance of metal contacts onto graphene were investigated by using properly designed test patterns. While a sheet resistance Rsh ≈ 1.7 kΩ/sq and a specific contact resistance ρc ≈ 15 kΩ·μm have been measured for graphene transferred onto SiO2, about 2.3× higher Rsh and about 8× higher ρc values were obtained for graphene on PEN. High-resolution current mapping by torsion resonant conductive atomic force microscopy (TRCAFM provided an insight into the nanoscale mechanisms responsible for the very high ρc in the case of graphene on PEN, showing a ca. 10× smaller “effective” area for current injection than in the case of graphene on SiO2.

  16. Ag paste-based nanomesh electrodes for large-area touch screen panels

    Science.gov (United States)

    Chung, Sung-il; Kyeom Kim, Pan; Ha, Tae-gyu

    2017-10-01

    This study reports a novel method for fabricating a nickel nanomesh mold using phase shift lithography, suitable for use in large-area touch screen panel applications. Generally, the values of light transmittance and sheet resistance of metal mesh transparent conducting electrode (TCE) films are determined by the ratio of the aperture to metal areas. In this study, taking into consideration the optimal light transmittance, sheet resistance, and pattern visibility issues, the line width of the metal mesh pattern was ~1 µm, and the pitch of the pattern was ~100 µm. In addition, a novel method of manufacturing wiring electrodes using a phase shift lithography process was also developed and evaluated. A TCE film with a size of 370 mm  ×  470 mm was prepared and evaluated for its light transmittance and sheet resistance. In addition, wiring electrodes with a length of 70 mm were fabricated and their line resistances evaluated by varying their line width.

  17. Large-area laser nano-texturing with user-defined patterns

    International Nuclear Information System (INIS)

    Li, L; Guo, W; Wang, Z B; Whitehead, D; Liu, Z; Luk'yanchuk, B

    2009-01-01

    Writing nano-sized features less than the diffraction limit of the lasers efficiently over a large area requires special technology development. This paper reports the use of a self-assembled particle lens array with near-field enhancement effect to write millions of nano-sized user-defined features, e.g. English letters, lines, curves, simultaneously by angular beam scanning. About a 5 mm × 5 mm area can be written with a single shot of a laser beam or few scans for up to 100 million identical features of nano or sub-micro scales. With the help of certain environmental conditions, such as the use of a suitable chemical solution in conjunction with the particle lens array, the characteristic of the features produced can be further controlled, including the generation of reversed (e.g. pits become hills and grooves become walls) features of laser-written patterns. The technical challenges, experimental findings and theoretical analysis/simulation are presented

  18. Large-scale patterns of turnover and Basal area change in Andean forests.

    Directory of Open Access Journals (Sweden)

    Selene Báez

    Full Text Available General patterns of forest dynamics and productivity in the Andes Mountains are poorly characterized. Here we present the first large-scale study of Andean forest dynamics using a set of 63 permanent forest plots assembled over the past two decades. In the North-Central Andes tree turnover (mortality and recruitment and tree growth declined with increasing elevation and decreasing temperature. In addition, basal area increased in Lower Montane Moist Forests but did not change in Higher Montane Humid Forests. However, at higher elevations the lack of net basal area change and excess of mortality over recruitment suggests negative environmental impacts. In North-Western Argentina, forest dynamics appear to be influenced by land use history in addition to environmental variation. Taken together, our results indicate that combinations of abiotic and biotic factors that vary across elevation gradients are important determinants of tree turnover and productivity in the Andes. More extensive and longer-term monitoring and analyses of forest dynamics in permanent plots will be necessary to understand how demographic processes and woody biomass are responding to changing environmental conditions along elevation gradients through this century.

  19. Low temperature diamond growth by linear antenna plasma CVD over large area

    International Nuclear Information System (INIS)

    Izak, Tibor; Babchenko, Oleg; Potocky, Stepan; Kromka, Alexander; Varga, Marian

    2012-01-01

    Recently, there is a great effort to increase the deposition area and decrease the process temperature for diamond growth which will enlarge its applications including use of temperature sensitive substrates. In this work, we report on the large area (20 x 30 cm 2 ) and low temperature (250 C) polycrystalline diamond growth by pulsed linear antenna microwave plasma system. The influence of substrate temperature varied from 250 to 680 C, as controlled by the table heater and/or by microwave power, is studied. It was found that the growth rate, film morphology and diamond to non-diamond phases (sp 3 /sp 2 carbon bonds) are influenced by the growth temperature, as confirmed by SEM and Raman measurements. The surface chemistry and growth processes were studied in terms of activation energies (E a ) calculated from Arrhenius plots. The activation energies of growth processes were very low (1.7 and 7.8 kcal mol -1 ) indicating an energetically favourable growth process from the CO 2 -CH 4 -H 2 gas mixture. In addition, from activation energies two different growth regimes were observed at low and high temperatures, indicating different growth mechanism. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Investigation on a short circuit of large-area OLED lighting panels

    International Nuclear Information System (INIS)

    Park, J W; Kim, T W; Park, J B

    2013-01-01

    A short circuit often arises from large-area organic light-emitting device (OLED) lighting panels due to particles (i.e. dust, organic or metal debris) or the spike-like surface of the indium–tin–oxide (ITO) anode. On the emergence of a short circuit, an instant current crowding occurs, thereby reducing substantially the resistance of the panels and causing a failure of a dimming control. In this paper, we investigate the effect of the surface morphology of ITO on the resistance and dimmability of the panels. We have demonstrated that the peak-to-valley roughness of ITO should be much less than 20 nm or the resistance of the panels should be much higher than 1 MΩ in order to avoid an unwanted short-circuit phenomenon and thus achieve the high-yield fabrication of OLED lighting panels. It is also addressed that much care is taken to ensure a dimming control of OLED lighting panels with a larger active area because the resistance of those panels varies depending more sensitively on the surface roughness of ITO. (paper)

  1. Large area window on vacuum chamber surface for neutron scattering instruments

    International Nuclear Information System (INIS)

    Itoh, Shinichi; Yokoo, Tetsuya; Ueno, Kenji; Suzuki, Junichi; Teraoku, Takuji; Tsuchiya, Masao

    2012-01-01

    The feasibility of a large area window using a thin aluminum plate on the surface of the vacuum chamber for neutron scattering instruments at a pulsed neutron source was investigated. In the prototype investigation for a window with an area of 1m×1.4m and a thickness of 1 mm, the measured pressure dependence of the displacement agreed well with a calculation using a nonlinear strain–stress curve up to the plastic deformation region. In addition, we confirmed the repetition test up to 2000 pressurization-and-release cycles, which is sufficient for the lifetime of the vacuum chamber for neutron scattering instruments. Based on these investigations, an actual model of the window to be mounted on the vacuum chamber of the High Resolution Chopper Spectrometer (HRC) at J-PARC was designed. By using a calculated stress distribution on the window, the clamping structure capable of balancing the tension in the window was determined. In a model with a structure identical to the actual window, we confirmed the repetition test over more than 7000 pressurization-and-release cycles, which shows a lifetime long enough for the actual usage of the vacuum chamber on the HRC.

  2. FERMI LARGE AREA TELESCOPE OBSERVATIONS OF THE VELA-X PULSAR WIND NEBULA

    International Nuclear Information System (INIS)

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Allafort, A.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Borgland, A. W.; Bouvier, A.; Baldini, L.; Bellazzini, R.; Bregeon, J.; Brez, A.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bonamente, E.; Brigida, M.; Bruel, P.

    2010-01-01

    We report on gamma-ray observations in the off-pulse window of the Vela pulsar PSR B0833-45 using 11 months of survey data from the Fermi Large Area Telescope (LAT). This pulsar is located in the 8 deg. diameter Vela supernova remnant, which contains several regions of non-thermal emission detected in the radio, X-ray, and gamma-ray bands. The gamma-ray emission detected by the LAT lies within one of these regions, the 2 deg. x 3 deg. area south of the pulsar known as Vela-X. The LAT flux is significantly spatially extended with a best-fit radius of 0. 0 88 ± 0. 0 12 for an assumed radially symmetric uniform disk. The 200 MeV to 20 GeV LAT spectrum of this source is well described by a power law with a spectral index of 2.41 ± 0.09 ± 0.15 and integral flux above 100 MeV of (4.73 ± 0.63 ± 1.32) x 10 -7 cm -2 s -1 . The first errors represent the statistical error on the fit parameters, while the second ones are the systematic uncertainties. Detailed morphological and spectral analyses give strong constraints on the energetics and magnetic field of the pulsar wind nebula system and favor a scenario with two distinct electron populations.

  3. Large-area few-layer MoS 2 deposited by sputtering

    KAUST Repository

    Huang, Jyun-Hong

    2016-06-06

    Direct magnetron sputtering of transition metal dichalcogenide targets is proposed as a new approach for depositing large-area two-dimensional layered materials. Bilayer to few-layer MoS2 deposited by magnetron sputtering followed by post-deposition annealing shows superior area scalability over 20 cm(2) and layer-by-layer controllability. High crystallinity of layered MoS2 was confirmed by Raman, photo-luminescence, and transmission electron microscopy analysis. The sputtering temperature and annealing ambience were found to play an important role in the film quality. The top-gate field-effect transistor by using the layered MoS2 channel shows typical n-type characteristics with a current on/off ratio of approximately 10(4). The relatively low mobility is attributed to the small grain size of 0.1-1 mu m with a trap charge density in grain boundaries of the order of 10(13) cm(-2).

  4. Multi-Satellite Observation Scheduling for Large Area Disaster Emergency Response

    Science.gov (United States)

    Niu, X. N.; Tang, H.; Wu, L. X.

    2018-04-01

    an optimal imaging plan, plays a key role in coordinating multiple satellites to monitor the disaster area. In the paper, to generate imaging plan dynamically according to the disaster relief, we propose a dynamic satellite task scheduling method for large area disaster response. First, an initial robust scheduling scheme is generated by a robust satellite scheduling model in which both the profit and the robustness of the schedule are simultaneously maximized. Then, we use a multi-objective optimization model to obtain a series of decomposing schemes. Based on the initial imaging plan, we propose a mixed optimizing algorithm named HA_NSGA-II to allocate the decomposing results thus to obtain an adjusted imaging schedule. A real disaster scenario, i.e., 2008 Wenchuan earthquake, is revisited in terms of rapid response using satellite resources and used to evaluate the performance of the proposed method with state-of-the-art approaches. We conclude that our satellite scheduling model can optimize the usage of satellite resources so as to obtain images in disaster response in a more timely and efficient manner.

  5. Large area, low capacitance Si(Li) detectors for high rate x-ray applications

    International Nuclear Information System (INIS)

    Rossington, C.S.; Fine, P.M.; Madden, N.W.

    1992-10-01

    Large area, single-element Si(Li) detectors have been fabricated using a novel geometry which yields detectors with reduced capacitance and hence reduced noise at short amplifier pulse-processing times. A typical device employing the new geometry with a thickness of 6 mm and an active area of 175 mm 2 has a capacitance of only 0.5 pf, compared to 2.9 pf for a conventional planar device with equivalent dimensions. These new low capacitance detectors, used in conjunction with low capacitance field effect transistors, will result in x-ray spectrometers capable of operating at very high count rates while still maintaining excellent energy resolution. The spectral response of the low capacitance detectors to a wide range of x-ray energies at 80 K is comparable to typical state-of-the-art conventional Si(Li) devices. In addition to their low capacitance, the new devices offer other advantages over conventional detectors. Detector fabrication procedures, I-V and C-V characteristics, noise performance, and spectral response to 2-60 keV x-rays are described

  6. {sup 10}B multi-grid proportional gas counters for large area thermal neutron detectors

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, K. [ESS, P.O. Box 176, SE-221 00 Lund (Sweden); Bigault, T. [ILL, BP 156, 6, rue Jules Horowitz, 38042 Grenoble Cedex 9 (France); Birch, J. [Linköping University, SE-581, 83 Linköping (Sweden); Buffet, J. C.; Correa, J. [ILL, BP 156, 6, rue Jules Horowitz, 38042 Grenoble Cedex 9 (France); Hall-Wilton, R. [ESS, P.O. Box 176, SE-221 00 Lund (Sweden); Hultman, L. [Linköping University, SE-581, 83 Linköping (Sweden); Höglund, C. [ESS, P.O. Box 176, SE-221 00 Lund (Sweden); Linköping University, SE-581, 83 Linköping (Sweden); Guérard, B., E-mail: guerard@ill.fr [ILL, BP 156, 6, rue Jules Horowitz, 38042 Grenoble Cedex 9 (France); Jensen, J. [Linköping University, SE-581, 83 Linköping (Sweden); Khaplanov, A. [ILL, BP 156, 6, rue Jules Horowitz, 38042 Grenoble Cedex 9 (France); ESS, P.O. Box 176, SE-221 00 Lund (Sweden); Kirstein, O. [Linköping University, SE-581, 83 Linköping (Sweden); Piscitelli, F.; Van Esch, P. [ILL, BP 156, 6, rue Jules Horowitz, 38042 Grenoble Cedex 9 (France); Vettier, C. [ESS, P.O. Box 176, SE-221 00 Lund (Sweden)

    2013-08-21

    {sup 3}He was a popular material in neutrons detectors until its availability dropped drastically in 2008. The development of techniques based on alternative convertors is now of high priority for neutron research institutes. Thin films of {sup 10}B or {sup 10}B{sub 4}C have been used in gas proportional counters to detect neutrons, but until now, only for small or medium sensitive area. We present here the multi-grid design, introduced at the ILL and developed in collaboration with ESS for LAN (large area neutron) detectors. Typically thirty {sup 10}B{sub 4}C films of 1 μm thickness are used to convert neutrons into ionizing particles which are subsequently detected in a proportional gas counter. The principle and the fabrication of the multi-grid are described and some preliminary results obtained with a prototype of 200 cm×8 cm are reported; a detection efficiency of 48% has been measured at 2.5 Å with a monochromatic neutron beam line, showing the good potential of this new technique.

  7. Maximum skin dose assessment in interventional cardiology: large area detectors and calculation methods

    International Nuclear Information System (INIS)

    Quail, E.; Petersol, A.

    2002-01-01

    Advances in imaging technology have facilitated the development of increasingly complex radiological procedures for interventional radiology. Such interventional procedures can involve significant patient exposure, although often represent alternatives to more hazardous surgery or are the sole method for treatment. Interventional radiology is already an established part of mainstream medicine and is likely to expand further with the continuing development and adoption of new procedures. Between all medical exposures, interventional radiology is first of the list of the more expansive radiological practice in terms of effective dose per examination with a mean value of 20 mSv. Currently interventional radiology contribute 4% to the annual collective dose, in spite of contributing to total annual frequency only 0.3% but considering the perspectives of this method can be expected a large expansion of this value. In IR procedures the potential for deterministic effects on the skin is a risk to be taken into account together with stochastic long term risk. Indeed, the International Commission on Radiological Protection (ICRP) in its publication No 85, affirms that the patient dose of priority concern is the absorbed dose in the area of skin that receives the maximum dose during an interventional procedure. For the mentioned reasons, in IR it is important to give to practitioners information on the dose received by the skin of the patient during the procedure. In this paper maximum local skin dose (MSD) is called the absorbed dose in the area of skin receiving the maximum dose during an interventional procedure

  8. Automated training site selection for large-area remote-sensing image analysis

    Science.gov (United States)

    McCaffrey, Thomas M.; Franklin, Steven E.

    1993-11-01

    A computer program is presented to select training sites automatically from remotely sensed digital imagery. The basic ideas are to guide the image analyst through the process of selecting typical and representative areas for large-area image classifications by minimizing bias, and to provide an initial list of potential classes for which training sites are required to develop a classification scheme or to verify classification accuracy. Reducing subjectivity in training site selection is achieved by using a purely statistical selection of homogeneous sites which then can be compared to field knowledge, aerial photography, or other remote-sensing imagery and ancillary data to arrive at a final selection of sites to be used to train the classification decision rules. The selection of the homogeneous sites uses simple tests based on the coefficient of variance, the F-statistic, and the Student's i-statistic. Comparisons of site means are conducted with a linear growing list of previously located homogeneous pixels. The program supports a common pixel-interleaved digital image format and has been tested on aerial and satellite optical imagery. The program is coded efficiently in the C programming language and was developed under AIX-Unix on an IBM RISC 6000 24-bit color workstation.

  9. APD arrays and large-area APDs via a new planar process

    CERN Document Server

    Farrell, R; Vanderpuye, K; Grazioso, R; Myers, R; Entine, G

    2000-01-01

    A fabrication process has been developed which allows the beveled-edge-type of avalanche photodiode (APD) to be made without the need for the artful bevel formation steps. This new process, applicable to both APD arrays and to discrete detectors, greatly simplifies manufacture and should lead to significant cost reduction for such photodetectors. This is achieved through a simple innovation that allows isolation around the device or array pixel to be brought into the plane of the surface of the silicon wafer, hence a planar process. A description of the new process is presented along with performance data for a variety of APD device and array configurations. APD array pixel gains in excess of 10 000 have been measured. Array pixel coincidence timing resolution of less than 5 ns has been demonstrated. An energy resolution of 6% for 662 keV gamma-rays using a CsI(T1) scintillator on a planar processed large-area APD has been recorded. Discrete APDs with active areas up to 13 cm sup 2 have been operated.

  10. Development of a detachable high speed miniature scanning probe microscope for large area substrates inspection

    Energy Technology Data Exchange (ETDEWEB)

    Sadeghian, Hamed, E-mail: hamed.sadeghianmarnani@tno.nl, E-mail: h.sadeghianmarnani@tudelft.nl [Department of Optomechatronics, Netherlands Organization for Scientific Applied Research, TNO, Stieltjesweg 1, 2628 CK Delft (Netherlands); Department of Precision and Microsystems Engineering, Delft University of Technology, Mekelweg 2, 2628 CD Delft (Netherlands); Herfst, Rodolf; Winters, Jasper; Crowcombe, Will; Kramer, Geerten; Dool, Teun van den; Es, Maarten H. van [Department of Optomechatronics, Netherlands Organization for Scientific Applied Research, TNO, Stieltjesweg 1, 2628 CK Delft (Netherlands)

    2015-11-15

    We have developed a high speed, miniature scanning probe microscope (MSPM) integrated with a Positioning Unit (PU) for accurately positioning the MSPM on a large substrate. This combination enables simultaneous, parallel operation of many units on a large sample for high throughput measurements. The size of the MSPM is 19 × 45 × 70 mm{sup 3}. It contains a one-dimensional flexure stage with counter-balanced actuation for vertical scanning with a bandwidth of 50 kHz and a z-travel range of more than 2 μm. This stage is mechanically decoupled from the rest of the MSPM by suspending it on specific dynamically determined points. The motion of the probe, which is mounted on top of the flexure stage is measured by a very compact optical beam deflection (OBD). Thermal noise spectrum measurements of short cantilevers show a bandwidth of 2 MHz and a noise of less than 15 fm/Hz{sup 1/2}. A fast approach and engagement of the probe to the substrate surface have been achieved by integrating a small stepper actuator and direct monitoring of the cantilever response to the approaching surface. The PU has the same width as the MSPM, 45 mm and can position the MSPM to a pre-chosen position within an area of 275×30 mm{sup 2} to within 100 nm accuracy within a few seconds. During scanning, the MSPM is detached from the PU which is essential to eliminate mechanical vibration and drift from the relatively low-resonance frequency and low-stiffness structure of the PU. Although the specific implementation of the MSPM we describe here has been developed as an atomic force microscope, the general architecture is applicable to any form of SPM. This high speed MSPM is now being used in a parallel SPM architecture for inspection and metrology of large samples such as semiconductor wafers and masks.

  11. Probing Millisecond Pulsar Emission Geometry Using Light Curves From the Fermi Large Area Telescope

    Science.gov (United States)

    Venter, Christo; Harding, Alice; Guillemot, L.

    2009-01-01

    An interesting new high-energy pulsar sub-population is emerging following early discoveries of gamma-ray millisecond pulsars (MSPs) by the Fermi Large Area Telescope (LAT). We present results from 3D emission modeling, including the Special Relativistic effects of aberration and time-of-flight delays and also rotational sweepback of 13-field lines, in the geometric context of polar cap (PC), slot gap (SG), outer gap (OG), and two-pole caustic (TPC) pulsar models. In contrast to the general belief that these very old, rapidly-rotating neutron stars (NSs) should have largely pair-starved magnetospheres due to the absence of significant pair production, we find that most of the light curves are best fit by SG and OG models, which indicates the presence of narrow accelerating gaps limited by robust pair production -- even in these pulsars with very low spin-down luminosities. The gamma-ray pulse shapes and relative phase lags with respect to the radio pulses point to high-altitude emission being dominant for all geometries. We also find exclusive differentiation of the current gamma-ray MSP population into two MSP sub-classes: light curve shapes and lags across wavebands impose either pair-starved PC (PSPC) or SG / OG-type geometries. In the first case, the radio pulse has a small lag with respect to the single gamma-ray pulse, while the (first) gamma-ray peak usually trails the radio by a large phase offset in the latter case. Finally, we find that the flux correction factor as a function of magnetic inclination and observer angles is typically of order unity for all models. Our calculation of light curves and flux correction factor f(_, _, P) for the case of MSPs is therefore complementary to the "ATLAS paper" of Watters et al. for younger pulsars.

  12. Enhanced Methodologies to Enumerate Persons Experiencing Homelessness in a Large Urban Area.

    Science.gov (United States)

    Troisi, Catherine L; D'Andrea, Ritalinda; Grier, Gary; Williams, Stephen

    2015-10-01

    Homelessness is a public health problem, and persons experiencing homelessness are a vulnerable population. Estimates of the number of persons experiencing homelessness inform funding allocations and services planning and directly determine the ability of a community to intervene effectively in homelessness. The point-in-time (PIT) count presents a logistical problem in large urban areas, particularly those covering a vast geographical area. Working together, academia, local government, and community organizations improved the methodology for the count. Specific enhancements include use of incident command system (ICS), increased number of staging areas/teams, specialized outreach and Special Weapons and Tactics teams, and day-after surveying to collect demographic information. This collaboration and enhanced methodology resulted in a more accurate estimate of the number of persons experiencing homelessness and allowed comparison of findings for 4 years. While initial results showed an increase due to improved counting, the number of persons experiencing homelessness counted for the subsequent years showed significant decrease during the same time period as a "housing first" campaign was implemented. The collaboration also built capacity in each sector: The health department used ICS as a training opportunity; the academics enhanced their community health efforts; the service sector was taught and implemented more rigorous quantitative methods; and the community was exposed to public health as a pragmatic and effective discipline. Improvements made to increase the reliability of the PIT count can be adapted for use in other jurisdictions, leading to improved counts and better evaluation of progress in ending homelessness. © The Author(s) 2015.

  13. Swift delineation of flood-prone areas over large European regions

    Science.gov (United States)

    Tavares da Costa, Ricardo; Castellarin, Attilio; Manfreda, Salvatore; Samela, Caterina; Domeneghetti, Alessio; Mazzoli, Paolo; Luzzi, Valerio; Bagli, Stefano

    2017-04-01

    According to the European Environment Agency (EEA Report No 1/2016), a significant share of the European population is estimated to be living on or near a floodplain, with Italy having the highest population density in flood-prone areas among the countries analysed. This tendency, tied with event frequency and magnitude (e.g.: the 24/11/2016 floods in Italy) and the fact that river floods may occur at large scales and at a transboundary level, where data is often sparse, presents a challenge in flood-risk management. The availability of consistent flood hazard and risk maps during prevention, preparedness, response and recovery phases are a valuable and important step forward in improving the effectiveness, efficiency and robustness of evidence-based decision making. The present work aims at testing and discussing the usefulness of pattern recognition techniques based on geomorphologic indices (Manfreda et al., J. Hydrol. Eng., 2011, Degiorgis et al., J Hydrol., 2012, Samela et al., J. Hydrol. Eng., 2015) for the simplified mapping of river flood-prone areas at large scales. The techniques are applied to 25m Digital Elevation Models (DEM) of the Danube, Po and Severn river watersheds, obtained from the Copernicus data and information funded by the European Union - EU-DEM layers. Results are compared to the Pan-European flood hazard maps derived by Alfieri et al. (Hydrol. Proc., 2013) using a set of distributed hydrological (LISFLOOD, van der Knijff et al., Int. J. Geogr. Inf. Sci., 2010, employed within the European Flood Awareness System, www.efas.eu) and hydraulic models (LISFLOOD-FP, Bates and De Roo, J. Hydrol., 2000). Our study presents different calibration and cross-validation exercises of the DEM-based mapping algorithms to assess to which extent, and with which accuracy, they can be reproduced over different regions of Europe. This work is being developed under the System-Risk project (www.system-risk.eu) that received funding from the European Union

  14. Development of Standardized Mobile Tracer Correlation Approach for Large Area Emission Measurements (DRAFT UNDER EPA REVIEW)

    Science.gov (United States)

    Foster-wittig, T. A.; Thoma, E.; Green, R.; Hater, G.; Swan, N.; Chanton, J.

    2013-12-01

    Improved understanding of air emissions from large area sources such as landfills, waste water ponds, open-source processing, and agricultural operations is a topic of increasing environmental importance. In many cases, the size of the area source, coupled with spatial-heterogeneity, make direct (on-site) emission assessment difficult; methane emissions, from landfills for example, can be particularly complex [Thoma et al, 2009]. Recently, whole-facility (remote) measurement approaches based on tracer correlation have been utilized [Scheutz et al, 2011]. The approach uses a mobile platform to simultaneously measure a metered-release of a conservative gas (the tracer) along with the target compound (methane in the case of landfills). The known-rate tracer release provides a measure of atmospheric dispersion at the downwind observing location allowing the area source emission to be determined by a ratio calculation [Green et al, 2010]. Although powerful in concept, the approach has been somewhat limited to research applications due to the complexities and cost of the high-sensitivity measurement equipment required to quantify the part-per billion levels of tracer and target gas at kilometer-scale distances. The advent of compact, robust, and easy to use near-infrared optical measurement systems (such as cavity ring down spectroscopy) allow the tracer correlation approach to be investigated for wider use. Over the last several years, Waste Management Inc., the U.S. EPA, and collaborators have conducted method evaluation activities to determine the viability of a standardized approach through execution of a large number of field measurement trials at U.S. landfills. As opposed to previous studies [Scheutz et al, 2011] conducted at night (optimal plume transport conditions), the current work evaluated realistic use-scenarios; these scenarios include execution by non-scientist personnel, daylight operation, and full range of atmospheric condition (all plume transport

  15. Can limited area NWP and/or RCM models improve on large scales inside their domain?

    Science.gov (United States)

    Mesinger, Fedor; Veljovic, Katarina

    2017-04-01

    In a paper in press in Meteorology and Atmospheric Physics at the time this abstract is being written, Mesinger and Veljovic point out four requirements that need to be fulfilled by a limited area model (LAM), be it in NWP or RCM environment, to improve on large scales inside its domain. First, NWP/RCM model needs to be run on a relatively large domain. Note that domain size in quite inexpensive compared to resolution. Second, NWP/RCM model should not use more forcing at its boundaries than required by the mathematics of the problem. That means prescribing lateral boundary conditions only at its outside boundary, with one less prognostic variable prescribed at the outflow than at the inflow parts of the boundary. Next, nudging towards the large scales of the driver model must not be used, as it would obviously be nudging in the wrong direction if the nested model can improve on large scales inside its domain. And finally, the NWP/RCM model must have features that enable development of large scales improved compared to those of the driver model. This would typically include higher resolution, but obviously does not have to. Integrations showing improvements in large scales by LAM ensemble members are summarized in the mentioned paper in press. Ensemble members referred to are run using the Eta model, and are driven by ECMWF 32-day ensemble members, initialized 0000 UTC 4 October 2012. The Eta model used is the so-called "upgraded Eta," or "sloping steps Eta," which is free of the Gallus-Klemp problem of weak flow in the lee of the bell-shaped topography, seemed to many as suggesting the eta coordinate to be ill suited for high resolution models. The "sloping steps" in fact represent a simple version of the cut cell scheme. Accuracy of forecasting the position of jet stream winds, chosen to be those of speeds greater than 45 m/s at 250 hPa, expressed by Equitable Threat (or Gilbert) skill scores adjusted to unit bias (ETSa) was taken to show the skill at large scales

  16. Large area high quality silicon detectors for scientific research and radioactivity monitoring in the environment

    International Nuclear Information System (INIS)

    Frolov, D.; Perevertailo, V.; Frolov, O.; Kononenko, Yu.; Pugatch, V.; Rozenfeld, A.

    1995-01-01

    breakdown of the junction were detected and examined. Examination of gate-controlled junctions allows one to obtain a useful information on generation currents, breakdown effects, protective rings operation in detectors. Results of this research were in design of a series of the following Si detectors: detectors with active areas 0.1 to 20 cm 2 and a wide range of depletion depth; photodetectors capable of working together with scintillator; large area strip detector with 16 and 128 strips as well as an annular strip detector with 40 strips and a max strip diameter of 13 cm. (author)

  17. Synthesis and Applications of Large Area Graphene-Based Electrode Systems

    Science.gov (United States)

    Paul, Rajat Kanti

    Graphene is a single sheet of carbon atoms with outstanding electrical and physical properties and being exploited for applications in electronics, sensors, fuel cells, photovoltaics and energy storage. However, practical designs of graphene-based electrode systems and related experimental implementations are required to realize their widespread applications in nano- to bioelectronics. In this dissertation, different graphene-based electrode systems having metallic and semiconducting properties are synthesized optimizing process conditions. Also realized is the potential of the fabricated electrode systems by applying them in practical applications such as sensor devices and fuel cells. The zero bandgap of semimetal graphene still limits its application as an effective field-effect transistor device or a chemiresistor sensor operating at room temperature. It has been shown theoretically and experimentally that graphene nanoribbons (GNRs) or nanomeshes (GNMs) can attain a bandgap that is large enough for a transistor device, and hence would show high sensitivity to various gaseous species or biomolecules. Large-area mono- and bilayer graphene films are synthesized by a simple chemical vapor deposition (CVD) technique depending on the carbon precursors such as methane, acetylene and ethanol, and the results are compared using optical microscopy (OM), Raman spectroscopy, high-resolution transmission electron microscopy (HRTEM) and x-ray photoelectron spectroscopy (XPS). A simple reactive ion etching (RIE) combined with well-established nanosphere lithography is performed on the synthesized CVD-grown monolayer graphene platform to fabricate large area GNMs with specific dimension and periodicity. The fabricated GNMs chemiresistor sensor devices show excellent sensitivity towards NO2 and NH 3, significantly higher than their film counterparts. The GNM sensor devices exhibit sensitivities of about 4.32%/ppm (parts-per-million) in NO 2 and 0.71%/ppm in NH3 with estimated

  18. Validation and evaluation of common large-area display set (CLADS) performance specification

    Science.gov (United States)

    Hermann, David J.; Gorenflo, Ronald L.

    1998-09-01

    Battelle is under contract with Warner Robins Air Logistics Center to design a Common Large Area Display Set (CLADS) for use in multiple Command, Control, Communications, Computers, and Intelligence (C4I) applications that currently use 19- inch Cathode Ray Tubes (CRTs). Battelle engineers have built and fully tested pre-production prototypes of the CLADS design for AWACS, and are completing pre-production prototype displays for three other platforms simultaneously. With the CLADS design, any display technology that can be packaged to meet the form, fit, and function requirements defined by the Common Large Area Display Head Assembly (CLADHA) performance specification is a candidate for CLADS applications. This technology independent feature reduced the risk of CLADS development, permits life long technology insertion upgrades without unnecessary redesign, and addresses many of the obsolescence problems associated with COTS technology-based acquisition. Performance and environmental testing were performed on the AWACS CLADS and continues on other platforms as a part of the performance specification validation process. A simulator assessment and flight assessment were successfully completed for the AWACS CLADS, and lessons learned from these assessments are being incorporated into the performance specifications. Draft CLADS specifications were released to potential display integrators and manufacturers for review in 1997, and the final version of the performance specifications are scheduled to be released to display integrators and manufacturers in May, 1998. Initial USAF applications include replacements for the E-3 AWACS color monitor assembly, E-8 Joint STARS graphics display unit, and ABCCC airborne color display. Initial U.S. Navy applications include the E-2C ACIS display. For these applications, reliability and maintainability are key objectives. The common design will reduce the cost of operation and maintenance by an estimated 3.3M per year on E-3 AWACS

  19. Development of a large area thermal neutron detector based on a scintillator

    International Nuclear Information System (INIS)

    Engels, Ralf

    2012-01-01

    In the present work, the development and construction of a detector prototype based on wavelength shifting fiber in combination with a scintillator has been investigated and optimized. This development aims at an alternative for large area neutron detectors based on "3He detectors, which was the main construction in the past. After the study of the components and assemblies, such as: the scintillator, the wavelength-shifting-fibers and available photomultiplier tubes, the construction of the first prototype module begun. The neutron converter was selected as a "6LiF/ZnS scintillator, which produces a big light yield per absorbed neutron. The prototype itself is square and has an edge length of 30 cm in combination with two orthogonal layers of crossed wavelength-shifting-fibers. The top fiber layer, which is closer to the "6LiF/ZnS top scintillator produces the x-coordinates and the lower layer produces the y-coordinates for each event. In the prototype, MSJ-fibers from the company Kuraray were used with 1 mm diameter and spacing in the top layer of 1.5 mm and 1 mm in the lower layer. Due to the orthogonal arrangement of the wires in the two layers, one may identify where the neutron was absorbed in the scintillator and produced the light yield. In order to reduce the light loss of the absorbed photons inside the fibers, a bending radius of greater than 20 mm was used and achieved by warming up the fibers to 80 C during the bending process. The increased temperature reduces the crack formation in the fibers which increases the light loss. At this time it is expected that a photomultiplier from Hamamatsu with 256 individual pixels for readout will be used. This H9500 flat panel photomultiplier has the advantage of readout of all fibers of the prototype in one photomultiplier housing. In combination with integrated readout electronics one can minimize the homogeneity/gain differences of the photocathode pixels, the different light loss in each fiber, and the gain

  20. Large-area SnO2: F thin films by offline APCVD

    International Nuclear Information System (INIS)

    Wang, Yan; Wu, Yucheng; Qin, Yongqiang; Zhang, Zhihai; Shi, Chengwu; Zhang, Qingfeng; Li, Changhao; Xia, Xiaohong; Sun, Stanley; Chen, Leon

    2011-01-01

    Highlights: → Large-area (1245 mm x 635 mm) FTO thin films were successfully deposited by offline APCVD process. → The as-prepared FTO thin films with sheet resistance 8-11 Ω/□ and direct transmittance more than 83% exhibited better than that of the online ones. → The maximum quantum efficiency of the solar cells based on offline FTO substrate was 0.750 at wavelength 540 nm. → The power of the solar modules using the offline FTO as glass substrates was 51.639 W, higher than that of the modules based on the online ones. -- Abstract: In this paper, we reported the successful preparation of fluorine-doped tin oxide (FTO) thin films on large-area glass substrates (1245 mm x 635 mm x 3 mm) by self-designed offline atmospheric pressure chemical vapor deposition (APCVD) process. The FTO thin films were achieved through a combinatorial chemistry approach using tin tetrachloride, water and oxygen as precursors and Freon (F-152, C2H4F2) as dopant. The deposited films were characterized for crystallinity, morphology (roughness) and sheet resistance to aid optimization of materials suitable for solar cells. We got the FTO thin films with sheet resistance 8-11 Ω/□ and direct transmittance more than 83%. X-ray diffraction (XRD) characterization suggested that the as-prepared FTO films were composed of multicrystal, with the average crystal size 200-300 nm and good crystallinity. Further more, the field emission scanning electron microscope (FESEM) images showed that the films were produced with good surface morphology (haze). Selected samples were used for manufacturing tandem amorphous silicon (a-Si:H) thin film solar cells and modules by plasma enhanced chemical vapor deposition (PECVD). Compared with commercially available FTO thin films coated by online chemical vapor deposition, our FTO coatings show excellent performance resulting in a high quantum efficiency yield for a-Si:H solar cells and ideal open voltage and short circuit current for a-Si:H solar